Permian-Triassic Evolution of Tethys and Western Circum-Pacific (Developments in Palaeontology and Stratigraphy)

Permian-Triassic Evolution of Tethys and Western Circum-Pacific FURTHER TITLES IN THIS SERIES i. A.J. Boucot Evoluti...

Author: Yin Hongfu | J.M. Dickins | G.R. Shi | Tong Jinnan

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Permian-Triassic Evolution of Tethys and Western Circum-Pacific

FURTHER TITLES IN THIS SERIES

i. A.J. Boucot Evolution and Extinction Rate Controls 2. W.A. Berggren and J.A. van Couvering The Late Neogene-Biostratigraphy, Geochronology and Paleoclimatology of the Last 15 Million Years in Marine and Continental Sequences 3. L.J. Salop Precambrian of the Northern Hemisphere 4. J.L. Wray Calcareous Algae 5. A. Hallam (Editor) Patterns of Evolution, as lllustrated by the Fossil Record 6. F.M. Swain (Editor) Stratigraphic Micropaleontology of Atlantic Basin and Borderlands 7. W.C. Mahaney (Editor) Quaternary Dating Methods 8. D. Jan6ssy Pleistocene Vertebrate Faunas of Hungary 9. Ch. Pomerol and I. Premoli-Silva (Editors) Terminal Eocene Events lO. J.C. Briggs Biogeography and Plate Tectonics 11. T. Hanai, N. Ikeya and K. Ishizaki (Editors) Evolutionary Biology of Ostracoda. Its Fundamentals and Applications 12. V.A. Zubakov and I.I. Borzenkova Global Palaeoclimate of the Late Cenozoic 13. F.P.Agterberg Automated Stratigraphic Correlation

14. J.C. Briggs Global Biogeography 15. A. Montanari, G.S. Odin and R. Coccioni (Editors) Miocene Stratigraphy: An Integrated Approach 16. F.M. Swain Fossil Nonmarine Ostracoda of the United States 17. H. Okada and N.J. Mateer (Editors) Cretaceous Environment of Asia

DEVELOPMENTS IN PALAEONTOLOGYAND STRATIGRAPHY, 18

Permian-Triassic Evolution of Tethys and Western Circum-Pacific Edited by

Hongfu Yin

China University o[ Geoscience, Faculty of Geosiences, Wuhan, Hubei, China

J.M. Dickins Turner, Australia

G.R. Shi

School of Aquatic Science and Natural Resources Management, Clayton, Australia

Jinnan Tong

Paleontology Laboratory, China University of Geosciences, Wuhan, Hubei, China

supported by the National Science Foundation of China (NSFC)Project no. 49632070.

2000 ELSEVIER Amsterdam - Lausanne- New York- Oxford - Shannon - S i n g a p o r e - Tokyo

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First edition 2000 Library of Congress

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in P u b l i c a t i o n

A catalog record from the Library of Congress

ISBN: 0-444-50154-

Data h a s b e e n a p p l i e d for.

l

T h e p a p e r u s e d in t h i s p u b l i c a t i o n m e e t s t h e r e q u i r e m e n t s P r i n t e d in T h e N e t h e r l a n d s .

of ANSI/NISO

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(Permanence

of Paper).

CONTENTS List of contributors

vii

Preface Hongfu YIN, J.M. DICKINS, G.R. SHI, Jinnan TONG

xiii

Part 1. Permian-Triassic strata and palaeogeography Paleoclimatic constraints for Early Permian paleogeography of Eastern Tethys Jiaxin YAN and Hongfu YIN The Permian of Russia and CIS and its interregional correlation G.V. KOTLYAR

17

The Permian of South Europe and its interregional correlation G. CASSINIS, EDi STEFANO, F. MASSARI, C. NERI and C.VENTURINI

37

The Permian of China and its interregional correlation Yugan JIN and Qinghua SHANG

71

The Permian of Vietnam, Laos and Cambodia and its interregional correlation Cu Tien PHAN

99

The Permian of New Zealand and its interregional correlation H.J. CAMPBELL

lll

Permian-Triassic successions in Japan: key to deciphering Permian/Triassic events Y. EZAKI and A. YAO

127

Latest Permian and Triassic carbonates of Russia: new palaeontological findings, stable isotopes, Ca-Mg ratio and correlation Y.D. ZAKHAROV, N.G. UKHANEVA, A.V. IGNATYEV, T.B. AFANASYEVA, G.I. BURYI, E.S. PANASENKO, A.M. POPOV, T.A. PUNINA and A.K. CHERBADZHI

141

The Triassic of the Alps and Carpathians and its interregional correlation A. VOROS

173

The Triassic of China and its interregional correlation Hongfu YIN and Yuanqiao PENG

197

The Triassic of Indochina peninsula and its interregional correlation Vu KHUC

221

The Marine Triassic of Australasian and its interregional correlation H.J. CAMPBELL and J.A. GRANT-MACKIE

235

The northern margin of Gondwanaland: uppermost Carboniferous to lowermost Jurassic and its correlation J.M. DICKINS

257

Magnetic susceptibility and organic carbon isotopes of sediments across some marine and terrestrial Permo-Triassic boundaries H.J. HANSEN, S. LOJEN, P. TOFT, T. DOLENEC, Jinnan TONG, E MICHAELSEN and A. SARKAR

271

Part 2. Permian-Triassic biotic evolution

Evolution of the Permian and Triassic Foraminifera in South China Jinnan TONG and G.R. SHI

291

Radiolarian evolution during the Permian and Triassic transition in South and Southwest China Qinglai FENG, Fengqing YANG, Zhenfang ZHANG, Ning ZHANG, Yongqun GAO and Zhiping WANG

309

Asian-western Pacific Permian Brachiopoda in space and time: biogeography and Extinction patterns G.R. SHI and Shuzhong SHEN

327

Ammonoid Succession Model across the Paleozoic-Mesozoic transition in South China Fengqing YANG and Hongmei WANG

353

On zonation and evolution of Permian and Triassic conodonts Xulong LAI and Shilong MEI

371

vii

LIST O F C O N T R I B U T O R S 1. T.B. Afanasyeva, Far Eastern Geological Institute, Far Eastern Branch, Russian Academy of Sciences, Prospect Stoletiya Vladivostoka, 159, Vladivostok 690022, Russia 2. G.I. Buryi, Far Eastern Geological Institute, Far Eastern Branch, Russian Academy of Sciences, Prospect Stoletiya Vladivostoka, 159, Vladivostok 690022, Russia 3. H.J. Campbell, Institute of Geological & Nuclear sciences, Crown research Dunedin, 764 Cumberland Street, Private Bag, Dunedin, New Zealand. Fax: +61 3 4775232 4. G. Cassinis, Dipartimento di Scienze della Terra dell'Universitat~, Via Ferrata 1, 1-27100 Pavia, Italy, E-mail: [email protected] 5. A.K. Cherbadzhi Far Eastern Geological Institute, Far Eastern Branch, Russian Academy of Sciences, Prospect Stoletiya Vladivostoka, 159, Vladivostok 690022, Russia 6. J.M. Dickins, Innovative Geology, 14 Bent St., Turner, Canberra A. C. T. 2612, Australia, E-mail: [email protected] 7. T. Dolenec, Josef Stefan Institute, Ljubljana, Slovenia 8. Y. Ezaki, Department of Geosciences, Osaka City University, Sugimoto 3-3-138, Sumiyochi--ku, Osaka 558-8585, Japan, E-mail: [email protected], ac.jp 9. Qinglai Feng, Faculty of Geosciences, China University of Geosciences, Wuhan, Hubei, China, 430074 10. Yongqun Gao, Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, The People's Republic of China 11. J.A. Grant-Mackie, Geology Department, University of Auckland, Private Bag, Auckland, New Zealand, E-mail: [email protected], Fax: +64 9 3737435 12. H.J. Hansen, Geological Institute, University of Copenhagen, Oster Voldgade 10.DK1350 Kopenhagen, Denmark, E-mail: [email protected] 13. A.V. Ignatyev, Far Eastern Geological Institute, Far Eastern Branch, Russian Academy of Sciences, Prospect Stoletiya Vladivostoka, 159, Vladivostok 690022, Russia 14. Yugan Jin, Nanjing Institute of Geology & Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China, E-mail: ygjin@public 1.ptt.js.cn, Fax: +86-025-3375200 15. Vu Khuc, Geological Museum, 6 Pham Ngu Lao, Hanoi, Vietnam, E-mail: [email protected], Fax: 84 4 254734 16. G.V. Kotlyar, All-Russian Research Geological Institute (VSEGEI), Sredny pr., 74, St. Petersburg, 199106, Russia, E-mail: [email protected] 17. Xulong Lai, Faculty of Geosciences, China University of Geosciences, Wuhan, Hubei, China, 430074. 18. S. Lojen, Josef Stefan Institute, Ljubljana, Slovenia

viii 19. F. Massari, Dipartimento di Geologia, Paleontologia e Geofisica dell'Universit/i, Via Giotto 1, I-35137 Padova 20. Shilong Mei, Faculty of Geosciences, China University of Geosciences, Beijing, 100083, E-mail: [email protected] 21. P. Michaelsen, Earth Sciences, James Cook University, Townsville, Australia 22. C. Neri, Dipartimento di Scienze Geologiche dell'Universit/~. Corso Ercole I d'Este 32, 144100 Ferrara 23. E.S. Panasenko, Far Eastern Geological Institute, Far Eastern Branch, Russian Academy of Sciences, Prospect Stoletiya Vladivostoka, 159, Vladivostok 690022, Russia 24. Yuanqiao Peng, Faculty of Geosciences, China University of Geosciences, Wuhan, Hubei, China, 430074 25. Cu Tien Phan, Research Institute of Geology and Mineral Resources, Thanh Xuan, Dong Da, Ha Noi, Vietnam, Fax" 84 45 42125 26. A.M. Popov, Far Eastern Geological Institute, Far Eastern Branch, Russian Academy of Sciences, Prospect Stoletiya Vladivostoka, 159, Vladivostok 690022, Russia 27. T.A. Punina Far Eastern Geological Institute, Far Eastern Branch, Russian Academy of Sciences, Prospect Stoletiya Vladivostoka, 159, Vladivostok 690022, Russia 28. A. Sarkar, Indian School of Mines, Dhanbad, India 29. Qinghua Shang, Nanjing Institute of Geology & Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China, Fax: +86-025-3375200 30. Shuzhong Shen, School of Ecology and Environment, Deakin University, Rusden Campus, 662 Blackburn Road, Clayton, Victoria 3168, Australia 31. G.R. Shi, School of Ecology and Environment, Deakin University, Rusden Campus, 662 Blackburn Road, Clayton, Victoria 3168, Australia, E-mail" [email protected], Fax: +61 3 92447276 32. P. Di Stefano, Dipartimento di Geologia e Geodesia dell'UniversitY., Via E.Toti 91, 190128 Palermo 33. P. Toft, Geological Institute, University of Copenhagen, Oster Voldgade 10.DK-1350 Kopenhagen, Denmark 34. Jinnan Tong, Faculty of Geosciences, China University of Geosciences, Wuhan, Hubei, China, 430074, E-mail: [email protected] 35. N.G. Ukhaneva, Far Eastern Geological Institute, Far Eastern Branch, Russian Academy of Sciences, Prospect Stoletiya Vladivostoka, 159, Vladivostok 690022, Russia 36. C. Venturini, Dipartimento di Scienze della Terra e Geologico-Ambientali dell'Universit/i. Via Zamboni 67, 1-40127 Bologna 37. A. V6r6s, Geological and Paleontological Department, Hungarian Natural History Museum, Museum krt. 14-16, H-1088 Budapest, Hungary, E-mail: voros@paleo. nhmus.hu 38. Hongmei Wang, Faculty of Geosciences, China University of Geosciences, Wuhan, Hubei, China, 430074. 39. Zhiping Wang, Faculty of Earth Sciences, China University of Geosciences, Wuhan

430074, The People's Republic of China 40. Jiaxing Yan, Faculty of Geosciences, China University of Geosciences, Wuhan, Hubei, China, 430074. 41. Fengqing Yang, Faculty of Geosciences, China University of Geosciences, Wuhan, Hubei, China, 430074. 42. A. Yao, Department of Geosciences, Osaka City University, Sugimoto 3-3-138, Sumiyochi--ku, Osaka 558-8585, Japan 43. Hongfu Yin, Faculty of Geosciences, China University of Geosciences, Wuhan, Hubei, China, 430074, E-mail: [email protected], Fax: +86 27 87803392; 44. Y.D. Zakharov, Far Eastern Geological Institute, Far Eastern Branch, Russian Academy of Sciences, Prospect Stoletiya Vladivostoka, 159, Vladivostok 690022, Russia, E-mail: [email protected] 45. Ning Zhang, Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, The People's Republic of China 46. Zhenfang Zhang, Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, The People's Republic of China

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About the editor Yin Hongfu, Academician of Academia Sinica, President of China University of Geosciences (Wuhan, Hubei), Professor of Geology. Leader of IGCP Project no. 359 and chairman of the International Permian Triassic Boundary Working Group under ISC. He published 160 papers and is the co-author (or editor) of eighteen books, among which seven published in English: 1. Permo-Triassic events in the eastern Tethys. Cambridge University Press, Cambridge, 1992; 2. Geological events of Permo-Triassic transitional period in South China. Geological Publishing House, Beijing, 1993; 3. The Palaeobiogeography of China. Oxford Science Publica, ion, Oxford, 1994; 4. The Palaeozoic-Mesozoic Boundary. China University of Geoscience Press, 1996; 5. Late Palaeozoic and Early Mesozoic Circum-Pacific events and their global correlation. Cambridge University Press, 1997; 6. The Permian-Triassic boundary and global triassic correlations. Palaeo-geography,climatology, -ecology. Special issue, 143(4), 1998; 7. Proceedings of the International Conference on Pangea and the Paleozoic-Mesozoic transition. China University of Geosciences Press, 1999.

Correspondence: Faculty of Geosciences, China University of Geosciences, Wuhan, Hubei, China, 430074. Tel: 0086 27 7806812; Fax: 0086 27 7801763; E-mail: [email protected]

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xiii

Preface Hongfu YIN

a,

J.M. DICKINS

b,

G.R. SHI c, Jinnan TONG

a

a Faculty

of Earth Science, China University of Geosciences, Wuhan, Hubei, 430074, China Geology, 14 Bent St, Turner, A.C.T. 2612, Australia c School of Ecology and Environment, Deakin University, Rusden Campus, 662 Blackburn

b Innovative

Rd., Clayton, VIC 3168, Australia

1. INTRODUCTION Permian and Triassic are the interval known for the integration and separation of Pangea, the closure of the Palaeo-Tethys and the opening of Meso-Tethys. They were associated with a series of worldwide events including the Late Palaeozoic glaciation and succeeding extensive evaporatic and reef formations, the end-Palaeozoic regression, strong orogenies (Hercynian, Uralian, Hunter-Bowen and Indosinian) and wide-spread volcanism (e.g. the Tunguss Trap and the Emeishan Basalt) and magmatism, and finally, the Permo-Triassic biotic macro-extinction. These events resulted in the formation of enormous reserves of coal, petroleum, evaporites, phosphorites and metal resources. The Permian and Triassic thus constitutes a time interval particularly important both for understanding the Earth's history and for exploration of mineral resources. It was toward this aim that the IGCP (INTERNATIONAL GEOLOGICAL CORRELATION PROGRAMME) project no. 359 (1993-1997) was established. This project is named LATE PALAEOZOIC AND EARLY MESOZOIC EVENTS OF TETHYS, CIRCUM-PACIFIC AND MARGINAL GONDWANA. To reconstruct the history of Pangea, Palaeo-Tethys and Palaeo-Pacific through stratigraphic, palaeogeographic and other interdisciplinary approaches, our efforts are concentrated on two tasks, which comprises the two parts of this volume. Part 1 deals with regional stratigraphy which is the basis for interregional correlation, and palaeogeography. Part 2 focuses on the events at the Permian-Triassic transition. Because the definition of Permian-Triassic Boundary (PTB) has been discussed in other publications [1-3], this book will concentrate on biotic evolution.

xiv 2. PART 1 Part 1 covers southern Europe, Russia, China, Indochina, Australasia and Japan. Cassinis et al. examined the Permian of southern Europe which essentially consists of continental terrigenous and volcanic deposits, as well as intrusive bodies. The authors emphasized a wide-spread "Mid-Permian'unconformity subdividing Permian (and Upper Carboniferous) into a lower fault-bounded basin infilling sequence and an upper continuous blanketing sequence, and related them to tectonic regime. Marine sediments of the westernmost Tethys, i.e. in Italian, ex-Yugoslav and Greek areas were emphatically described, and considered to be mainly Tethyan with certain influence of the northern sea. This relatively comprehensive review discussed regional stratigraphy, and presents palaeogeographic and other geological interpretations. The Triassic of southern Europe, accentuating on the Alpine-Carpathian region, was dealt with by Vor6s. He subdivided this region into four major terranes and described their stratigraphy, ammonoid zonation and facies in comparison with those of the epicontinental southern Europe and northern Africa. Discussion on the palaeogeographical positions of the terranes led to the conclusion that the crustal fragments carrying the later Alpine-Carpathian terranes were in close connection with the Eurasian continental shelf in the Triassic. Based on extensive past studies and especially recent progress in the Upper Permian, Kotlyar et al. summarized the Permian of CIS and Russia. This vast territory was subdivided into a Biarmian (traditional East European) and a Tethyan (near-equatorial) realm. A few provinces of the Biarmian realm were discussed and a generalized stratigraphic scale together with correlation among the provinces was given. Notwithstanding with the advantages of the lower Permian world stratotype [4] and the progress made in the Upper Permian of the Volga area [5], the author unbiasedly commented on the advantages and disadvantages of the Russian scale in correlation with the international scale. The Tethyan (near-equatorial) scale, exclusively based on marine strata, was widely used for subdividing the Permian deposits in the southern regions of Russia and CIS. Discovery of Changhsingian in most parts of this area has been a remarkable progress. As correctly signified by the authors, its subdivision was mostly based on foraminifers and thus their correlation with conodonts and ammonoids as well as more precise demarcation of stage boundaries need improvements. Instead of giving a general review, the Triassic of Russia and CIS was investigated by Zakharov et al. with stable isotopes and Ca-Mg ratio, plus invertebrates on Changhsingian and Early Triassic. Seven geochemical events have been discovered and interpreted as due to high bio-productivity of marine basins in conditions of transgressions and warm climate. Through global correlation, it was suggested that thermal maxim in the Tethys existed during early Changhsingian, middle Olenekian, early Anisian and early Norian. Based on the Permian time scale proposed and agreed upon by the majority during his chairmanship of SPS [6], Jin, and his colleague Shang, presented a refined regional

XV

chronostratigraphic scheme for the Permian of China, a summary of the Permian stratigraphic framework in major depositional basins and a tentative correlation between the regional Permian sequences. The paper confirmed the translocation of the "Late Carboniferous' Chuanshanian rocks into Lower Permian, corresponding to Cisuralian. The Lopingian correlation is refined based on bio-, magneto-, and sequence stratigraphy. Problems of correlation with international scheme due to biogeographic differentiation are also discussed. According to Yin and Peng, fragmentation of Chinese blocks ended and the Chinese continent integrated for the first time in Triassic. Sediments and biota of the Triassic of China were temperature-controlled and can be subdivided into six regions. Stratigraphic sequences of representative areasof these regions, plus Tibet-Qinghai and South China subregions, are indicated, and summarized into synthetic chart with different fossil zonations. Correlation with adjacent areas is briefly discussed. Triassic strata constitute a 2 nd order sequence set with a remarkable two-fold character (four 2 nd order sequences) and twelve 3 rd order sequences. Influence of the Indosinian Orogeny on the Triassic sequences and their distribution is emphasized. The Permo-Triassic of Indochina was composed of a mosaic of pro-Cathaysian and proGondwanan blocks separated by micro-oceans and seaways, which caused complication in stratigraphic correlation. At this stage, we can only start from description and preliminary correlation of the concerned strata. Phan's paper mainly dealt with the Permian of ex-French Indochina but accompanied by correlation with South China and other parts of Indochina. Although still using the Vietnamese twofold subdivision, the author admits that the newly suggested international standard better suits the situation of Indochina, especially the bases of Wuchiapingian (Dzhulfian, Upper Permian). Fusulinids are of special significance in dating and correlating Permian of this region, and the application of conodonts remains to be worked out. Khuc's paper subdivided the Triassic of Indochina into two types: the An Chau type with volcanogenic Anisian overlying on unconformity surface and Carnian either terrestrial or absent, and the Song Da type with carbonate Anisian conformable with Lower Triassic and Halobia-bearing marine Carnian. The first type is restricted to pro-Cathaysian blocks and thus the sequence is apparently controlled by the Indosinian Orogeny. The second type involves various sequences scattered in the seaways and epicontinental seas around the blocks. Triassic of Australasia and Permian of New Zealand were described by Campbell & GrantMackie and Campbell respectively, in terms of terranes, their known faunal content, biostratigraphic age control and correlation, both inter-terrane and regional. Considering the diverse tectonic settings and the fragmented sequences it is admirable that Campbell and Grant-Mackie managed to summarize what is known of the marine Triassic strata of Australasia and in particular New Zealand, New Caledonia, Australia, P a p u a - New Guinea and eastern Indonesia. All preserved sequences are related to the break-up of eastern Gondwanaland, demise of Tethys and development of the Australian Plate margin. Interestingly, the authors emphasized biostratigraphic gaps for Ladinian and Carnian time,

xvi which correspond to the first phase of Indosinian Orogeny in Eurasia. Permian rocks in New Zealand are recognized within six terranes. Stratigraphically coherent fossiliferous successions are confined to two of these terranes, which are host to all documented New Zealand Permian biostratigraphic units. Correlation, often through indirect links with palaeotropics, Russia and North America, shows however that virtually all Permian stages exist in New Zealand. The basic tectonic framework of the Japanese Islands was generated through subduction of the Panthalassa Ocean plates during Paleozoic to Mesozoic time. The paper of Ezaki and Yao first introduced this framework with special reference to the pre-Jurassic terranes, six in southwest Japan plus South Kitakami in Northeast Japan, and Permo-Triassic exotic blocks in Jurassic terranes. Recent progress on biostratigraphy based on radiolarians and conodonts has made it possible to elucidate pelagic Permo-Triassic sequences and their correlation with epicontinental deposits, which had been extensively studied previously. Accordingly, researches on Permo-Triassic events in pelagic settings, including the extinction-recovery process and corresponding environmental changes, got large impetus. Palaeobiogeography, especially South Kitakami was in situ or derived from Gondwana, also attracts attention. Hansen et al. viewed the Permo-Triassic event from two peculiar points--the magnetic susceptibility and organic carbon isotopes. They were able to correlate the Permo-Triassic boundary strata of 7 sections from three continents with magnetic susceptibility pulses at the resolution of Milankovic cycles, i.e. 20ka and 100ka. Despite traditional belief that magnetic susceptibility varies with weathering and thus highly environment-depending, such coincidence of pulses with biotic changes in sections may provide a new tool in high resolution stratigraphy. The organic carbon isotopic signals also gave high resolution correlation between some marine and terrestrial sections. Different from other regional papers focusing on stratigraphy, Dickins's paper on the northern margin of Gondwanaland mainly argues for his long-term concept of Tethys and Gondwanaland [7,8]. He claimed that there was no continuous sea from Africa to the Himalayas and further east in the latest Carboniferous and earliest Permian. During Asselian and early Sakmarian the sea of Gondwanan margin was characterized by glaciation, which had only temporary connection with the northern warm-water Central Asian Sea. In his sense the Tethys was only established since mid-Permian as a continuous warm-water seaway existed from southern Asia to southern Europe and northern Africa. From Late Permian through Triassic the northern shore of Gondwanaland can be traced with a southern sediment source. As Dickins has been working so long on Gondwanan Permian, his idea, quite different from the popular view of Tethys as depicted by Dercourt et al. and Scotese et McKerrow, probably will arouse interesting arguments. A majority of the papers have shown, either through direct indication or through implication, that Permo-Triassic stratigraphy, paleontology and paleogeography of the Tethyan, marginal Gondwanan and western Circum-Pacific can be best interpreted by an

xvii

archipelagic ocean model [9,10]. This was highlighted by Yan and Yin's paper in which Tethys was illustrated as an "unclean' ocean with many archipelagos, a mosaic of seas and lands including: rifted blocks and valleys, seaways; microplates and micro-oceans; and island arcs and marginal seas. The foregoing (northerly) blocks were accreting to Eurasia, while the back (southerly) ones were rifting away from Gondwana. Reconstruction in this paper emphasizes on paleoclimatic constraints but they also accord with tectonic, paleomagnetic and biogeographic data. This archipelagic model of Tethys accords with paleomagnetic and biogeographic data that Eurasia and Gondwana were widely apart, and also accords with the facts that deep ocean deposits and typical oceanic ophiolites were few, because according to this model the vast distance was filled by islands and micro-oceans and seas. Though still wedge-shaped toward west, this view is quite different from the traditional view and has attracted considerable attention.

3. PART 2 Part Two of this volume deals with the events at Permo-Triassic transition, and naturally concentrates on bioevents. Tong and Shi's paper based on the data from South China indicates that the Permian foraminifers experienced two episodes of mass extinction: end-Guadalupian and end-Changhsingian. The recovery did not started until the Middle Triassic and the genuine Mesozoic ecosystem was not fully organized until the Late Triassic. Foraminifer groups of different microstructures and compositions of tests had very distinctive evolutions during the great transition. The Permo-Triassic events resulted in the most significant transformation in the history of the Foraminiferida, that is: the alternation from the Late Paleozoic calcareous microgranular groups to the Mesozoic-Cenozoic hyaline perforate calcareous forms. Feng et al. revealed that not only shallow benthos, but also pelagic radiolarians suffered end-Permian extinction. The recovery of the Triassic radiolarian fauna began in early Anisian and considerable diversity was reached in middle and late Anisian. An interesting phenomenon is that progenitors of Mesozoic radiolarians probably already occurred in latest Changhsingian. As radiolarian evolution across the Paleozoic-Mesozoic boundary have been poorly reported except in Japan and Sicily, this report may have its significance beyond its regional scope. The paper of Shi and Shen worked on Permian brachiopod events using statistical analysis on a large database of the Asian-western Pacific region. Six intervals were subdivided and a review of the Permian marine provincialism was introduced as a framework. It was revealed that the Permian brachiopod diversity and extinction patterns are broadly compatible among the Gondwanan, Palaeo-equatorial and Boreal Realms as well as with those of the Asianwestern Pacific region. Similar to foraminifers two major extinction events are recognized:

xviii end-Guadalupian and Changhsingian, the former most pronounced in the Gondwanan and Boreal Realms, whereas the latter only in the Palaeo-equatorial and Gondwanan Realms, but much more severe and time-concentrated. They also found that there is a good correlation in timing between the end-Guadalupian extinction and an Asian-western Pacific regression. Unlike foraminifers and brachiopods, Yang and Wang recognized seven ammonoid extinction events from Late Permian to Early Triassic, of which the end-Permian event is the largest. Most of the seven extinctionevents coincide with geological boundaries of either series or stages, and exhibit cyclic pattern consisting of newborn explosion, relative stable development and mass extinction, which the authors named as the "stage model'. In the Early Triassic, the ammonoids recovered stepwise and radiated to high diversity and biologically high level much quicker than that of other organisms. The authors considered the intrinsic (biological) factors of ammonoids (speciation, evolution rate and adaptibility) as the key to the promptness of ammonoid evolution. Besides the end-Permian event, the conodont paper by Lai and Mei focused on conodont zonation and provincialization of whole Permian and Triassic. Being climate-controlled, conodont biogeography was subdivided into two bipolar and one equatorial provinces in Permian but remained undivided in Triassic. They recognized four stages and four events for Permian and six stages and seven events for Triassic, attributed respectively to what they named as Substitute Pattern and Extinction-Survival-Recovery Pattern. Permian zonation was established for warm and cool water respectively and 26 zones are proposed for Triassic.

4. S U M M A R Y

Contributions of this volume may be summarized into three aspects. First, Permian and Triassic regional stratigraphy of Tethys and western Circum-Pacific, especially of areas so far insufficiently known, or areas with remarkable progress recently, are extensively reported. Second, based on these data new views of Tethys in Pangea time, different from the popular patten given by Scotese and McKerrow, are suggested. To synthesize Permian-Triassic and test new views of Pangea and Tethys, data of so far less reported areas and facies are required, such as the Middle East and deep sea facies. Thirdly, besides comprehensive indication and interpretation, researches of the biotic alteration and causative global changes at the PermianTriassic transition are now being carried out concurrently taxis by taxis, which has revealed that the procedure was multi-phasic, more variable and irregular than previously thought. This turning point of geological history is an interval of worldwide events happened in causality like a string of time-bombs, which provides excellent material for high resolution subdivision and correlation. We need cooperation among researchers such as under new IGCP projects to press onward along these directions, to achieve a better understanding of Permian-Triassic stratigraphic framework, environmental change and resource distribution, so as to serve the

xix

society and to enlighten the effort of mankind on sustainable development.

REFERENCES

1.

H.-F. Yin, W.C. Sweet, B.F. Glenister, G. Kotlyar, H. Kozur, N.D. Newell, J. Sheng, Z.-Y. Yang and Y.D. Zakharov, Recommendation of the Meishan section as Global Stratotype Section and Point for basal boundary of Triassic System. Newsl. Stratigr., 34(2)(1996) 81-108.

2.

Yin Hongfu (ed.), The Palaeozoic-Mesozoic Boundary--Candidates of the Global Stratotype Section and Point (GSSP) of the Permian-Triassic boundary. China University of Geosciences Press (1996) 135pp.

3.

G.Lucas and Yin Hongfu (eds.), 1998, The Permian-Triassic boundary and global triassic correlations. Palaeo-geography, -climatology,-ecology. Special issue, 143(4), 215pp.

4.

V.I. Davydov, B.F. Glenister, C. Spinosa, S.M. Ritter, V.V. Chernykh, B.R. Wardlaw and W.S. Snyder, Proposal of Aidaralash as Global Stratotype Section and Point (GSSP) for base of the Permian System, Episodes, 21, N 1, (1998) 11-18.

5.

N.K. Esaulova, V.R. Lozovsky and A.Yu. Rozanov (eds.) Stratotypes and Reference

Sections of the

Upper Permian in the regions of the Volga and Kama rivers, Moscow (1998). 6.

Y.G. Jin, B.R. Wardlaw, B.F.Glenister and G.V. Kotlyar, Permian chronostratigraphic subdivisions. Episodes, 20(1 ) (1997) 10-15.

7.

J.M.Diickins, The nature of the oceans of Gondwanaland, fact or fiction.

In Gondwana Nine 1:387-

8.

J.M.Diickins, The southern margin of Tethys. In Gondwana Nine 2:1125-1134. Oxford & IBH

396. Oxford & IBH Publishing Co. Pvt.Ltd, New Delhi (1994). Publishing Co. Pvt.Ltd, New Delhi (1994). 9.

Yin Hongfu, Tethys-an archipelagic ocean model. Proc. 30th Int'l Geol. Congr., vol.11 (1998) 91-97.

10. Yin Hongfu, Wu Shunbao, Du Yuansheng, Yan Jiaxin and Peng Yuanqiao, South China as a part of archipelagic Tethys during Pangea time. In Yin Hongfu and Tong Jinnan (eds.): Proceedings of the International Conference on Pangea and the Paleozoic-Mesozoic transition, China Univ. Geos. Press, Wuhan (1999) 69-73.

This Page Intentionally Left Blank

Persian-Triassic Evolutionof Tethysand WesternCi,cum-Pacific H. Yin, J.M. Dickins,G.R. Shi and J. Tong(Editors) o 2000ElsevierScienceB.V. All rightsreserved.

Paleoclimatic constraints for Early Permian paleogeography of Eastern Tethys ~ Jiaxin YAN and Hongfu YIN Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, People's Republic of China

East and Southeast Asia comprise a complex mosaic of allochthonous continental blocks. Smaller blocks among them are commonly ill-constrained in the Permo-Triassic paleogeographic reconstruction due to limited paleomagnetic data of high quality. Paleoclimatic constraint on the position of block is employed in this paper. A brief review of temporal and spatial distributions of paleoclimatic indicators revealed that the climatic regime in the Permian and, possibly, Late Triassic was of zonal circulation. The Chihsian (Early Permian) paleogeography is emphasized, in which paleoclimatic constraints inferred from changing climatic patterns are consistent with biogeographic and tectonic data and render satisfactory results. For example, the Qiangtang and Sibumasu blocks were located in the southern margin of the southern subtropical zone, and the Changning-Menglian ocean spanned the whole southern subtropical zone with a width about 10 degrees in latitude. The resulting paleogeography of Chihsian Subepoch is the pattern of an archipelago. It is also noted that Monodiexodina, a characteristic element of Permian transitional fauna, may also be present in warm-water deposits.

1. INTRODUCTION Much advancement has been achieved on the timing of amalgamation and accretion of blocks in the eastern Asia in the last decade. Recently, considerable attention has been directed to the reconstruction of eastern Tethys around the Paleozoic - Mesozoic transition[ 13]. A remarkable trend in the reconstruction is the increase in number of discerned blocks in the region. Additionally, configuration of eastern Tethys as an archipelago is emerging[4-6]. Accordingly, constraints on the reconstruction become of great concern. Generally, useful constraints on a reconstruction come from tectonic, paleomagnetic, biogeographic and paleoclimatic data. Although paleomagnetic data has been pre-eminent in recent years for interpreting paleolatitudes on most Paleozoic reconstruction, available paleomagnetic data for most of the smaller blocks in the region are still sparse and their reliability needs to be evaluated. Climatically sensitive deposits have long been used as evidence for the mobility of continents. Their potential latitudinal constraints were commonly used as independent "This work is supportedby the NationalNatural Science Foundationof China Project, No: 49632070).

verification of paleomagnetic data and even apparent polar wandering paths when the zonal circulation was proved[7,8]. In this paper, paleoclimatic constraints on block position are employed, emphasizing the Early Permian, because the Early Permian is the optimal interval to discriminate blocks of Gondwanan affinities from those of Cathaysian aff'mities in the light of paleoclimatic evidences. Four interesting paleogeographical problems, important but not fully resolved, will be detailed as examples of paleoclimatic constraints on the Early Permian paleogeography. Interestingly, the Early Permian is also the period that mixed fauna were well-recognized[9,10]. Wherever appropriate, thus, biogeographical and tectonic data will be incorporated in the discussion. As it is the first epoch of our Permo-Triassic paleogeographic reconstruction, we will briefly introduce the blocks in eastern Tethys and review the PermoTriassic paleoclimates relevant to our discussion of paleoclimatic constraints on positioning of the blocks.

2. BLOCKS IN EASTERN TETHYS Before further discussion, it is necessary to summarize current knowledge on the blocks in the eastern Tethys. East and Southeast Asia comprise a complex mosaic of allochthonous continental blocks separated by suture zones or large faults. The suture zones represent the remnants or sites of former ocean basins that once separated the now juxtaposed pieces of continental lithosphere in the region. As the blocks were non-rigid, they might have been modified by successive episodes of crustal shortening and strike-slip faulting, especially during the collision of India with Eurasia and subsequent northward indentation of India in the Cenozoic. In order to minimize the modification and to facilitate the further fit in the computer, some strike-slip fault belts were applied here (Fig. 1). The Indo-China, Sibumasu and western Burma blocks of Southeast Asia are modified from Metcalfe (1991)[ 11]. It is noted that the Tengchong-Baoshan region shows differences from the other sectors of the Sibumasu (or Shan-Thai) block in both sedimentary and faunal features[10]. For simplicity, the Tengchong-Baoshan region is still enclosed in the Sibumasu block here. The Lanping-Simao Block is separated from Indo-China Block along the NanLuang Prabang strike-slip fault belt[12,13]. In South China, the Lower Yangtze, Upper Yangtze, Cathaysia, Zhong-zan, Hainan Island and Bayan Har blocks are modified from Yin et al (1999)[5]. The North Qinling and South Qinling blocks originated from the Mid-Qinling microplate of early to middle Paleozoic age, which rifled from the Upper Yangtze block in Cambrian to Ordovician time and docked along the southwestern margin of North China in the Silurian. The resultant small oceanic basin to the south of the Mid-Qinling microplate was mainly closed in Late Silurian to Early Devonian, but deep-water radiolarian chert persisted to early or even later Carboniferous in the southwestern part (the Mianxian-Lueyang ophiolite melange belt)[5,14]. Eastward, Permian deeper shelf black shales, marls, cherts and small Hercynian alkalic intrusions at places still marked the closed oceanic basin. Interestingly, the Mid-Qinling microplate was separated into two slivers, namely South and North Qinling, in the Late Paleozoic, by a ritt trough evidenced by a belt of Late Devonian to Middle Triassic deep water deposits from Zheng'an to Xiahe[5]. It was the deep rift basin that separated the North China and South China blocks in the Late Paleozoic. The rift basin was wedge-shaped, opening to the west with a width above 1000 km in the Permian and it closed completely in

late Middle Triassic[ 14-16]. It is thus reasonable to treat the North and South Qinling blocks independently in terms of their movement in the Late Paleozoic. Mongolia block is similarly def'med as the Armuria of Zonenshain et al (1990)[ 17] and the southern Mongolia arcs ofNie et al (1990)[3]. It must be recognized, however, that a variety of allochthonous terrains in the eastern end, e. g. the Nadanhada terrain of Shao and Tang (1995)[18], should be excluded from this block. As the assemblage of North China, Qilian, Tarim and. Junggar had completed before Permian[3,19-22], only their boundaries in PaleoTethys are reiterated here. The Altun strike-slip fault separated Tarim to the northwest, and Qaidam and South Kunlun to the southeast (Fig.l). The Qilian and Qaidam blocks were separated by the North Zongwulong Fault, which is the western extension of the coeval ritt belt in Qinling region. This interpretation is supported by Triassic turbidites and talus in the region[23]. The Qaidam and South Kunlun blocks are separated by the median Kunlun ophiolite belt, which was closed in late Early Permian[24, 25].

Figure 1 Sketch map showing blocks in eastern Tethys. Abbreviations used: Ata, AnatolideTauride; Bay, Bayan Har; Cat, Cathaysia; Cp, Central Pamir; Dzi, Dzirula; EAAC, Eastern Anatolian Accretionary Complex; Far, Farah Rud; Hai, Hainan Island; Hel, Helmand; Koh, Kohistan; Lad, Ladakh; Las, Lanping-Simao; Lya, Lower Yangtze; Nir, NW Iran; Nql, North Qinling; Pon, Pontide; Qai, Qaidam; Qia, Qiangtang; Qil, Qilian; Sbm, Sibumasu; Sku, South Kunlun; Sp, Southern Pamir; Sql, South Qinling; SS, Sanadaj Sirjan; Tan, Tanghla-Qamdo; Tsh, Tianshuihai; Wbu, Western Burma; Yan, Yangtze; Zho, Zhong-zan. The Tianshuihai block is def'med by the Maza-Kangxiwar ophiolite belt to the north, by the Kongka Pass fault to the south, by the Altun strike-slip fault to the southeast and by the Karakorum fault to the southwest. Although the Tianshuihai is similar to Bayan Har in the development of Triassic turbidites[26,27], they are treated separately as they are distantly displaced by the Altun strike-slip fault. The Kongka Pass fault is the west part of the northern boundary of Early Permian fauna of Gondwana aff'mities[28]. However, the eastern extension

of the boundary is unclear. Permian faunas with Gondwana aff'mities are largely confined to the western Qiangtang region. Here the Qiangtang block is def'med tentatively to the west of the line connecting Yanghu and Dongqiao. To the east is the Tanghla-Qamdo block. Although the nature of the conjectured line is uncertain, biogeographical and sedimentary features of the two blocks were distinct in Permo-Triassic periods. The Lhasa Block is bounded by the Banggongco-Nujiang suture to the north and the Indus-Yarlung Zangbo suture to the south. Blocks to the west and southwest of Tibet are described in detail by Girardeau et al (1989)[29], Seng6r et al (1991)[30] and Zonenshain et al (1990)[ 17]. For simplicity, terrains in Turkey were grouped into two: the northern Pontides and the southern Anatolide-Tauride[31,32].

3. PERMO-TRIASSIC CLIMATES OF EASTERN TETHYS

3.1. Indicators of paleoelimate Paleoclimatic indicators include climate-sensitive deposits and inferences from biogeographic data[9,33]. Lithic paleoclimatic indicators include coal measures, bauxite, organic reefs, evaporites, carbonate ooids and deposits of definite glacial origin. The climatic significance of these indicators is discussed in numerous publications and will not be elaborated here. Noteworthy are the marine carbonate ooids, which form in modern warm environments of high salinity[34] and occur in ancient marine deposits with similar characteristics[35]. They have been used as potential indicators of warm, dry climatic conditions[7]. Also noteworthy is the paleoclimatic significance of fusulinid foraminifers. Their paleoclimatic significance is usually inferred from biogeographical data. As an integrated group, Ross and Ross (1985) considered fusulines to be tropical and subtropical[36]. In the Sverdrup Basin, Permian fusulines are present in the chloroforam and bryonoderm-extended skeletal grain associations of tropical-like to warm-temperate shelf carbonates, and disappear in the bryonoderm association of cold temperate shelf carbonates. In other words, fusulinids thrived in warm-water conditions but decreased in cool-water conditions there[37,38]. In the Salt Range, Pakistan, the lowest occurrence of fusulinids there, represented by Monodiexodina and Codonofusiella, are found in the Amb Formation. As climate ameliorated, the Amb Formation was overlain by the Wargal Formation with highly diverse fusulines of warm-water deposits (verified by the associated carbonate ooids)[39]. The Amb formation would be deposits of temperate conditions because the brachiopod and fusulinid faunas in the formation were thought to be transitional and mesothermal (the paleoclimatic significance of Permian transitional faunas will be discussed in detail later)[9] and is overlain directly by deposits of warm-water conditions. Both cases above show good levels of agreement concerning the paleoclimatic significance of fusulinids. An analogy may also be made to the distribution of large Cenozoic foraminifers along the southern Australia shelf, which are present in environments intermediate between warm- and cool-water carbonate realms, and disappear in cool-water environments[40]. It thus seems that fusulinids were limited to warm and warm-temperate environments, and decreased sharply in diversity with the drop of water temperature. Shelf carbonates with highly diverse fusulines, thus, are more appropriately assigned to warm-water deposits than to cool- and cold-water deposits. And the occurrence of fusulinids in the Early Permian shelf carbonates of the southern margin of Tethys would enable ambient temperatures equal to or above warm-temperate if exhumation and reworking

may be excluded. This inference is largely compatible with biogeographical data. In addition, we have noted that coal deposits is secondarily related to rainfall, and is mostly due to high groundwater table. As a reevaluation of Permo-Triassic coal beds for their paleoclimatic significance is not feasible at this time, the interpretation of coals as wet-climate indicators is incorporated with phytogeographic data and other climatic indicators throughout the following discussion.

3.2. Permo-Triassic paleoclimates in eastern Tethys Several significant changes characterize the Permo-Triassic distribution pattern of lithic paleoclimatic indicators in the region if a first-order trend is considered. In the Early Permian, two distinct dry climatic zones existed in the region. One, indicated by thick oolitic limestones and a fossil flora dominated by Walchia and Ullmannia[41], is present in the southern Junggar basin and Yili basin, northwestern China. This drier climatic zone was likely located at a paleolatitude about 30~ as inferred from the paleomagnetic data of the Tarim block to the south[42,43]. The other one, as will be seen later, is well represented by carbonates trapped in deposits of deep-water origin in the Changning-Menglian Belt, southwestern China (Fig.2). Coeval coal measures with Gigantopteris flora[33] occur on the Upper Yangtze, Cathaysia and North China blocks, and Bahama-type carbonates on the Tarim and Upper Yangtze blocks, indicating a warm and humid paleo-tropical zone. Three of the paleoclimatic zones shifted south in Late Permian, which may be attributed to the northward drift of the blocks. Consistent with the drift are indicators of dry climates, such as gypsum and redbeds that appear in the uppermost Permian of North China and Callipteris flora in the Upper Permian of Tarim[41,44]. The southern dry climatic zone occurs on the India block, as indicated by carbonate ooids in the Salt Range, Pakistan[39]. Coal measures of similar origin persisted from Early Permian to Late Permian in the South China region, and developed on the Tanghla-Qamdo block (Table 1). This pattern was apparently disrupted in the Triassic after the end of the Permian. Indicators of dry climates are found in the three zones mentioned above during the Early and Middle Triassic stages. For instance, thick evaporites and oolitic limestones of Early and Middle Triassic age occur widely in the South China region, and dolomitic and oolitic limestones in the India and Lhasa blocks. In the North China Block there occur thick purple or mottled fluviolacustrine clastic deposits which contain calcareous nodules, Pleuromeia-Voltzia flora, and lack coal deposits, indicating dry paleoclimates[44]. Interestingly, the zonal distribution pattern of lithic paleoclimatic indicators resumed in the region in the Late Triassic. Table 1 summarizes the changing climatic pattern during Permo-Triassic periods on blocks in a cross-Tethys profile from the Indian Block though the Tibetan Plateau to the Junggar Block. The blocks were chosen for they experienced considerable northward drift in the Permo-Triassic time and have relatively complete depositional records. Preliminary results show that marked differences exist on the two sides of paleo-Tethys. Blocks of Cathaysian affmities experienced a change from warm and humid climatic conditions through warm and dry to warm-temperate conditions. Climates on blocks of Gondwana aff'mities ameliorated in the Early Permian, becoming warm in the Maokouan, and dry in the Triassic. Blocks in the Tethys, e. g., the Tanghla-Qamdo, experienced changes from warm and humid climatic conditions to warm and dry climatic conditions. As longer time intervals are adopted here, minor climatic variations have been time-averaged.

Table 1 Permo-Triassic Paleoclimatic characteristics of main blocks in a cross-Tethys profile*

11

India Block India Block ~..............._~No_rthw_e_stern) ...... __ _.~N0_rt__heas_te_rn_ i ~ ~ ~ : - i - ~ ~ ~ _ t - ~ :

I's

........

Lhasa Block

Coal bed

TanghlaQamdo Block -~~:!]~-

Tarim Block

Junger Block :,1' i!I ~' Jl ~11'

-

Lopingian ~ [ iii

-_~........ ~

........ ~.......- ~ ~ .

.....~ _ _ :

N

~ i!jliji~[liii~llil!l[iii'!llii~,!!i;i:il,i

Maokouan ii:!llil;~i ~;ii~i] i ~ii:!;,ii~li,,!,;iii~li,iiii!,,~,;iil]ii~,ii;:!

~ ~

_ ~ - ] f

~!] Iranophyllum, ---~--i lpciphyllum,

~-~~~]~i~-_:: abundant fusulinids, i!;-~i~----i~:_~-i.-__--reefs

i-:=-.- :--

Abundant fusulinids

. .

:=

@a~gamo~teri~, E~de~, diamictites

Carbonates with fusulinids

Gangamopteris, diamictites

. . . . . . . . . . . . . . .

~

~

: ' if''

i'

'

-::--Z._--- L---_~ :_--.-:-

-]---]_-.-:i

Reefs and ~tromatolites : .

Chuanshanian

~,~, !'

Coal and abundant fusulinids Abundant fusulinids and some carbonate ooids

'"i, ':", ~~ri,-,,=,-:",~i!~i"-~'-!:',-~: :~ii-~;-: ~ -' !:'-:,- " ',~:~",' ;:l',~ I:~!! ~' ,' ' i!',i;', ; !~:~: ": :,: ;::

Uhihsian

I'

Coal

Abundant rusulinids and rare ooids

.

.

.

.

.

.

.

.

. .

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

-L .....

.

.

.

........ ...... .

.

.

.

.

.

.

.

.

.

.

= -=

.

.

.

.

.

i_- -U =.__--_-_-22 '_~;- --_--.=:.2~-_ 7.

I

---

: r .....

-]~_: : 2 - 7 7 - - - . _ - - - . . : _

2 . c_-_----

:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

Humid tropical (warm water)

Ii~-IIIIIiI~IIII-~!IIKilI:~UU~'[I~!i:IL~.IIII~I~/hI!~Ul! :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

h'ilh'hi.:l!!

*Note: Lithic paleoclimatic data and biogeographic data have been compiled mainly from works of Lin et al (1989)[45], Liu et al (1992)[46], Li and Wu (1994)[47], Wu et al (1995)[41 ], Wang (1990)[48], Wang (1985)[49], Bureau of Geology and Mineral Resource of Xinjiang (1991)[50] and Yin (1997)[51]. The Permian chronostratigraphic subdivisions are after Jin et al (1997)[52]. N for no recognized climatic indicators, where paleoclimate was conjecture based on geological context.

3.3. Paleoclimatic constraints on position of blocks

Global climatic patterns of zonal circulation may be modified by orographic, continental, and monsoonal effects. Because zonal circulation essentially parallels latitude, it is the zonal pattern that offers the most straightforward method for using paleoclimatic data to constrain paleolatitudes[7]. There is evidence for monsoonal circulation during the Pangea interval[7, 53-55]. Detailed discussions on climatic regime and on the origin of the apparent climatic changes at the P/T or T2/T3 boundaries mentioned above are beyond the scope of the present investigation. Nonetheless, zonal features of Permian age can not be excluded on the basis of present knowledge. For instance, the published biogeographic boundaries of the Permian roughly parallel paleolatitude[9,33]. Vast evaporite deposits of Permian age can be interpreted as the paleogeographic coincidence of large epeiric basins with the subtropics[56]. And it seems unlikely that the zonal pattern of lithic paleoclimatic indicators mentioned above in eastern Tethys could be explained by monsoonal or orographic effects. Combining paleomagnetic data with zonal distributions of lithic paleoclimatic indicators in the eastern Tethys, a zonal circulation is favored here for the Permian and possibly the Late Triassic as well. Application of paleoclimatic indicators to constrain paleolatitudes is best exemplified by the Tanghla-Qamdo block. Presently known biogeographic and tectonic data indicated that the block drii~ed north steadily during the Permian and Triassic periods till it docked along the northern margin of the Paleotethys in the Late Triassic time. On this block the Early Permian (here including the Chuanshanian, Chihsian and Maokouan subepoches) deposits are mainly carbonates, containing abundant fusulinids and some ooids. Upward is the thick coal measures of the Late Permian (Lopingian) with Gigantopteris flora (Table 1). Undoubtedly, this block would be located in the paleotropical zone in the Permian Period. This position is consistent with paleomagnetic latitudes of 13.2~ S or 16.1 ~ (Early Permian)[57]. In the Late Triassic, oolitic limestones and gypsum developed in the north portion of the block and coal measures in the southern portion. Such a spatial distribution pattern of climate-sensitive sediments suggests that the Tanghla-Qamdo block was just at the tropical/northern subtropical boundary in the Late Triassic. This position is consistent with paleomagnetic latitude of 26.4~ (Middle and Upper Triassic) from the block[58], and consistent with the Triassic paleomagnetic latitude of 31.1~ from its northern adjacent block (Kunlun)[59].

4. CHIHSIAN PALEOGEOGRAPHY OF EASTERN TETHYS 4.1. Location of Sibumasu Block

Early Permian in the Baoshan region includes the Dingiiazhai Formation, Woniusi Basalt, Bingma Formation and Shazipo Formation in ascending order. Chihsian deposits include the Bingma (or Yongde) Formation (marine clastic rocks and mudstones) and lower part of the Shazipo Formation (bioclastic limestones and oolitic limestones). The equivalent in the Tengchong region consists of bioclastic limestones and massive dolomitic limestones (Guanyinshan Formation and the lower part of the Dadongchang Formation)[60]. Undoubtedly the Shazipo Formation formed in an environment with warm and dry climatic conditions based on the occurrence of carbonate ooids. Brachiopod assemblages in the Bingma and Guanyinshan formations were assigned as cool-water "Costiferina-Waagenites" fauna and closely compared with those from the Wargal Formation and the overlying Chhidru

Formation of the Salt Range by Fang (1983)[61], Fang and Fan (1994)[62], and Shi and Archbold (1998)[10]. As mentioned above, the latter formations in the Salt Range are deposits of warm-water origin. Based on the comparison of brachiopod fauna to Salt Range, the Bingma and Guanyinshan formations were also warm-water deposits. Noteworthy is the fact that the brachiopod faunas from the Dingjiazhai and Bingma formations were assigned to a transitional, representing a temperate paleoclimatic condition, by Shi and Archbold (1995, 1998)[9,10]. A similar conclusion was reached by Fang (1994)[62]. We agree that the fauna exhibit transitional features. Nevertheless, we believe that a warm-temperate climatic condition is likely for the carbonate intercalations in the upper part of the Dingjiazhai Formation and in the Woniusi Basalt since moderately diverse fusulinids are present. At this point, it is reasonable to believe that the Chihsian deposits in the Tengchong-Baoshan region originated in warm-water, and possibly in a dry paleoclimate. The paleogeographical position of the Tengchong-Baoshan region during Chihsian time is not well constrained using presently known paleomagnetic data. For example, published values of 15.6~ 34.1~ and 43.75~ of paleomagnetic latitudes (on average) were reported for the Woniusi Basalt[63-65]. If northward drift of the region was consistent during the Permian, as demonstrated by biogeographical data[9,10], the changing climatic pattern mentioned above implies that the Tengchong-Baoshan region moved into the southern subtropical zone from the southern temperate zone during the Chihsia stage (Fig.2). For the whole Sibumasu block, similar positioning is likely despite the stratigraphical and biogeographical differences between the Tengchong-Baoshan region and the rest of the Sibumasu block[ 10]. 4.2. The Changning-Menglian ocean

To the east of the Tengchong-Baoshan region is the Changning-Menglian Belt (CMB). A consensus has developed in recent years that the siliceous deposits of Early Devonian to Middle Triassic age in the belt are of deep-water origin[66-67]. However, the importance of the CMB in palinspastic reconstruction is much debated in the literature. For example, whether the CMB was a broad ocean (Changning-Menglian Ocean: CMO) or merely a failed rift sag is unresolved[51 ]. Another related question is which belt, the CMB, the Lancangjiang belt or the Jinshajiang belt, was the demarcation line between blocks of Gondwana origin and those of Cathaysian origin. Paleoclimatically, both questions may be answered if it can be determined whether the CMB was the demarcation line between warm-water deposits and non-warm water deposits during the Permo-Carboniferous ice age. It was argued that "coolwater faunas" of Early Permian age occurred in the Lanping-Simao Block (to the east of Changning -Menglian and Lancangjiang belts), thus the Jinshajiang belt was the candidate for the demarcation line[68]. Recently, diamictites of Early Permian age were reported from the Lancangjiang belt by Nie et al (1997)[69], leading them to the belief that the Lancangjiang belt was the demarcation. Re-examination of the distribution pattern of Early Permian lithic paleoclimatic indicators within or adjacent to the CMB seems necessary. A stratigraphic unit of particular significance is a suite of oolitic limestones of shallowwater origin, continuous from Late Carboniferous to Early Permian, that are trapped in deposits of deep-water origin in the CMB[70,71]. It overlies Lower Carboniferous volcanic rocks that originated on a mid-ocean ridge or oceanic island[72]. The oolitic limestone unit, distinctive from its equivalents to the west (Baoshan and Tengchong region) and east (Lanping-Simao block), was believed to be the carbonate cape of oceanic islands formed in

the island archipelagos (CMO) that accreted to the western margin of the Lanping-Simao Block[70]. The presence of carbonate ooids in the unit has been confirmed by Yan et al (1999) [73]. As the development of marine carbonate ooids is restricted to low latitudes and strongly dependent on salinity, the carbonate unit concerned accumulated in a warm environment under a dry climate. Accordingly, the Changning-Menglian belt has been confirmed as the boundary separating the block of Gondwana aff'mities from that of Cathaysian affinities for the period from Late Carboniferous to Early Permian (Fig. 2). In addition, the "cold-cool water biota"[68] and "diamictites"[69] to the east of the CMB, as indicators of non-warm water conditions, need further substantiation.

Figure 2. Chihsian (Early Permian) paleogeography of Tethys, drawn schematically, emphasizing the position of blocks in the eastern Tethys. Lha=Lhasa; Nch-North China; Ich=Indochina. Other symbols as in Figure 1. 1, fluvial and lacustrine deposits; 2, marine sandstones and mudstones; 3, turbidite (flysch); 4, carbonate platform; 5, dolomites and dolomitic limestones; 6, evaporites (halite and anhydrite); 7, mid-ridge spreading system; 8, subduction zone; 9, transitional fauna; 10, Cathaysian Tethyan fauna; 11, coal deposits; 12, carbonate ooids; 13, algal reef; 14, conjecture position for the oolitic carbonate unit in the Changning-Menglian Ocean. In contrast, Chihsian equivalents on the Lanping-Simao block to the east possess little oolitic limestone, which is widespread in the subjacent interval. The Yangtze block spanned across the paleo-equator at that time[43]. Since the Lanping-Simao block shares many similarities with Yangtze block in Chihsian deposits and fauna, the Lanping-Simao Block should also be in the tropical zone in the Chihsian Subepoch. Because the Lanping-Simao Block was separated from Yangtze Block by a small oceanic basin[13], which was widest in the Early Permian[72], we suggest that the Lanping-Simao block was in the southern margin of the humid tropical zone during the Chihsian Subepoch. The CMO between the Sibumasu

10 and the Lanping-Simao blocks, thus, should span the whole southern subtropical zone with a width of about 10 degrees in paleolatitude in Chihsian time (Fig.2).

4.3. Positioning of Qiangtang block The typical Lower Permian succession on the Qiangtang Block is represented by the Doumar section, Rutog, which includes the Cameng, Zhanjin, Qudi, Tunlonggongba and Longge formations in ascending order[28, 74]. The Cameng and Zhanjin formations consist of sandstone, slate and diamictites with intercalations of basic volcanic rocks. No fossils were reported from the Cameng Formation. A Eurydesma fauna associated with the solitary corals Amplexocarina and Cyathaxonia was reported from the Zhanjin Formation[75]. The Qudi Formation is composed of sandstones, calcareous sandstones and slates with limestone intercalations in the upper part, in which fusulinids were abundant (32 species among 10 genera)[76]. The lower three formations are roughly correlated to the Horpatso Series of Norin (1946)[51] and were interpreted as turbidites with a total thickness of nearly 5000m. The Tunlonggongba Formation is dominated by bioclastic limestones with minor fine elastics in the lower part. Oolitic limestones were reported by Wu (1991) at the Bairebuco Section[77]. Interestingly, faunas in the Tunlonggongba Formation include not only characteristic Cathaysian genera such as Schubertella, Ipciphyllum and Polythecalis, but also typical "antitropical" genera such as Monodiexodina. The Longge Formation is composed of bioclastic, dolomitic and oolitic limestones with fossils characteristic for the Asian Tethyan region. The Chihsian strata in the region is the Tunlonggongba Formation[9, 78]. The "mixed fauna" in the Tunlonggongba formation has been attributed to fluctuations of water temperature derived from climatic changes[74,79] or the interplay of climatic amelioration and northward drifting of the block[9]. Although these explanations are possible, the "mixed fauna" may actually represent a warm environment that inherits its "mixed feature" from an active tectonic background. Firstly, a rifting scenario has been proposed[51], which is supported by the great stratal thickness and the occurrences of volcaniclastic rocks and turbidites. It is more likely that the active tectonic setting rather than the water temperature of the depositional environment was what governed the shallowing-upward succession from turbidites through shallow water elastics, alternations of elastics and carbonates to carbonates. Secondly, the faunas in the formation are not really "mixed". It was noted that faunas with distinct affinities occur separately (or alternately) in outcrops. Faunas with "Gondwana att'mities" or "antitropical" distributions are present in horizons of lower carbonate contents[74,79]. A similar phenomenon was shown in a biogeographical cluster analysis of Permian brachiopods[80]. This suggests that the "antitropicar' faunas there are the result of less favorable conditions related to an active tectonic background. To be more specific, the less favorable conditions might be attributed to a higher elastic influx rather than greater water depth or lower water temperature. Most importantly, indicators of a warm-water environment, such as oolitic limestones, are present locally in the formation and are widely distributed in the superjacent Longge Formation. Eastward, a similar sequence is present in the Chabu-Chasang area, visible despite being metamorphosed. The changing paleoclimatic pattern on the Qiangtang block is apparently comparable to that of Sibumasu. Paleogeographically, thus, the Qiangtang block should be located near the southern margin of the southern subtropical zone in the Chihsian Subepoch. A belief shared by many is that fauna with "antitropical distributions", best exemplified by

the fusuline Monodiexodina, are mesothermal and represent a temperate paleoclimatic condition. Monodiexodina occurs widely in the Chihsian strata on the Qiangtang and Sibumasu blocks. But it appears in warm-water environments on the two blocks as discussed above. The spatial distribution of the Chihsian transitional fauna plotted in Figure 2 also supported that some transitional faunas have extended into warm-water environments. Correlations of higher resolution will be necessary to eliminate possible time-averaged effects and to unravel this rather interesting problem. 4.4. Orientation of the India Block There are two solutions to the orientation of the India Block in eastern Gondwana during the Permo-Triassic periods. One is to fit the present southeastern margin of the India Block to Antarctica[I,2], and the other is to fit it to the northwestern margin of Australia[81 ]. Early Permian paleoclimatic data on the northern parts of the block have been reexamined to test which of the fits is favored paleoclimatically. Here the northwestern part of the India Block includes the Salt Range, Kashmir, Ladakh and Zanskar regions and the northeastern sector refers to areas to the east (Table 1). The Lower Permian in the northwestern part is well represented by successions outcropping in the Salt Range, Pakistan. As mentioned above, the Amb Formation which is the Chihsian equivalent was deposited in warm-temperate waters indicated by fusulinids. The overlying Wargal Formation of Maokouan age should be a warm-water deposit based on the occurrence of carbonate ooids[39]. By contrast, Chihsian faunas in the northeastern part, which are represented by successions in southern Tibet, were assigned as Gondwana-type[9]. Faunas in Maokouan Subepoch are similar to the "mixed fauna" of Shi and Archbold (1995). No Early Permian fusulinids were reported from the area[51 ] although a variety of bioclastic limestones are present. Similarly, few Early Permian conodonts were reported from the region[45]. Both conodonts and fusulinids are abundant there in Lopingian strata[45,82]. Hence, a cool- or cold-water and a warm-temperate environment are preferred, respectively, for the Chihsian and Maokouan deposits on the northeastern part (Table 1). The pattern of deposits of Early Permian age on the block suggests that a warm-water environment first invaded the northwestern part of the block, and then migrated northeastward. Such a retreat pattern means the temperature zonations on the block during the Early Permian intersected with the north margin and favors the first fit.

Figure 2 shows the Chihsian paleogeography of Tethys, emphasizing on the blocks of eastern Tethys. For reconstructions related to the blocks of South China, the reader is referred to works by Yin et al (1995, 1999)[5,14]. It should be pointed out that the map is not a standard projection and is highly schematic, especially with respect to the size and outline of the blocks. Nonetheless, the resulting land-sea configuration of eastern Tethys exhibits the archipelagic pattern of Yin (1998)[4-6].

5. CONCLUSIONS In summary, we delineate blocks in eastern Tethys and present a brief review on the temporal and spatial distributions of lithic paleoclimatic indicators in the region during the Permian and Triassic periods. Permo-Triassic paleoclimates in the region show considerable

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change. Apart from the Early Permian climatic amelioration on the peri-Gondwana blocks, remarkable climatic change occurred at the Permian/Triassic boundary and the Middle and Late Triassic boundary. And the climatic regime in the Permian and possibly in the Late Triassic was of zonal circulation, which ensures paleoclimatic constraints on the positioning o f the blocks. Paleolatitudinal information inferred from changing paleoclimatic patterns is consistent with biogeographic and tectonic data in the region, and is of particular significance for blocks without reliable paleomagnetic data. As far as paleoclimatic evidence is concerned, the Qiangtang and Sibumasu blocks were located in the southern margin of the southern subtropical zone, and the Changning-Menglian ocean spanned the whole southern subtropical zone with a width about 10 degrees in latitude in the Chihsian Subepoch. The resulting paleogeography of the Chihsian epoch is that of an archipelagic pattern. It is also noted that Monodiexodina, a typical element of Permian mixed fauna, appeared in warm-water deposits.

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Persian-TriassicEvolution of Tethys and WesternCircum-Pacific H. Yin, J.M. Dickins, G.R. Shi and J. Tong(Editors) e 2000 ElsevierScienceB.V. All rightsreserved.

Permian of the Russia and CIS and its interregional correlation G. V. KOTLYAR All-Russian Research Geological Institute (VSEGEI), Sredny pr., 74, St. Petersburg, 199106, Russia

Significant progress has been attained in the studies of the Upper Permian in the stratotype of the Permian System. The results of the studies conducted by many geologists and paleontologists on the Permian deposits in different regions of Russia and the CIS are generalized. The status of the traditional East-European (Biarmian) stratigraphic scale and the auxiliary regional Tethyan (near-equatorial) scale is reviewed in the light of the latest evidence. The latter scale has been widely used for subdividing the Permian deposits in the southern regions of Russia and the CIS. The advantages and disadvantages of each of the scales are considered. The boundaries of the Permian System and its series and stages of the East-European and Tethyan scales are analysed, their relationships and the possibilities of tracing are demonstrated. Correlation of the reference Permian sections in Biarmian and Tethyan realms is presented. Permian, stratigraphy, stage, zone, correlation.

1. Introduction The separation of Permian marine basins, endemism of faunas, an abrupt climatic zonation, widespread lagoonal and continental deposits complicate markedly interregional and transcontinental correlation and give rise to difficulties in the use of a global international standard. Permian deposits in Russia and the CIS are represented by diverse facies and formations of marine and continental basins. The main Permian paleogeographic elements within Russia and the CIS consist of two major realms with a predominantly marine sedimentary regime - the Biarmian and Tethyan, and a continental one - Angarida, separating them [ 1] (fig. 1). Significant differences in the composition of faunal communities in the Biarmian and Tethyan realms has resulted in the complicated use of two parallel scales - the traditional East-European (Biarmian) and Tethyan (near-equatorial) in Russia and the CIS. However, comprehensive use of the sequence-stratigraphy, lithofacies, biozonal and paleomagnetic methods reveals a number of extensively traced restructuring boundaries, dated reference levels, and transit (mixed) faunal assemblages permitting reliable correlations.

17

18

c~Tll

l.

J, O]]II]].

Iilrl

Ill, till! Ill

,,

41111

!14:: ~, lll,~'

I-r J ,w

iSnga

Y $

s

s

i J

AJ

Z7

Fig. 1. Zonation of Russia and the CIS in the Permian (outlines of paleobasins are also shown for contiguous areas). Land and sea distribution corresponds to the maximum of the Late Permian transgression. 1 - Land; 2 - Sea. Provinces" 1 - East-European, 2 - Pechora, 3 - Novaya Zemlya, 4 Taimyr-Khatanga, 5 - Verkhoyanye-Okhotsk, 6 - Kolyma-Omolon, 7 - Transbaikal, 8 Centre-Siberian, 9 - Altai-Sayan, 10 - Transcaucasus, 11 - Central Asia, 12 - Far East.

2. Permian of the Biarmian Realm The traditional scale of the Biarmian Realm, based on sections of the eastern part of the Russian Platform and Urals, is subdivided into two series, seven stages and 17 assemblage zones (fig. 2). Its lower boundary is drawn at the base of the conodont Streptognathodus isolatus Zone of the Asselian [2]. The upper boundary of the Permian System in the type area is placed in continental facies at the top of the Tatarian. However, there is a stratigraphic break of unclear extent in the stratotype at this level. Some researchers using paleomagnetic evidence believe that the Tatarian corresponds, at least, to four stages of the Tethyan scale including part of the Dorashamian (Changhsingian), and it should be subdivided into three independent stages [3]. According to another viewpoint, based on studies of tetrapods and event boundaries associated with eustasy, the Tatarian corresponds to the Midian, Dzhulfian and the lower part of the Dorashamian. The Vokhminsky Horizon of the Lower Triassic in Eastern Europe corresponds to the upper part of the Changhsingian [4].

19

E a s t - E u r o p e a n scale Zone d. o

[..

Suchonellina fragiloides Suchonellina futschiki

~6

o

Regional scheme

Conodonts

Vyatsky Severodvinsky it.,.

Darwinula fragilis

9IlK . 8 4

U rzhum sky 9 -I.:

_

Nemdinsky Darwinula fainae

Povolzhsky

b

Sheshm insky Darwinula

angusta

Solikam sky A c r a t i a sim ilaris Paraparchites humerosus Bairdia reussiana Parafusulina lutugini Parafusulina solidissima Pseudofusulina concavutas Pseudofusulina urdalensis Pseudofusulina verneuli Pseudofusulina m oelleri Schwagerina sphaerica P seudofusulina firm a Schwagerina m oelleri Pseudofusulina fecunda Schwagerina vulgaris Schwagerina fusiforms

----I~ b

Irensky Neostreptognathodus pnevi

Filippovsky Saraninsky Sarginsky

N. p e q u o p e n s i s

Irginsky Sweetognathus

whitei

S. p r i m us

Burtsevsky Sterlitam aksky

M. la ta

Tastubsky M. u r a l e n s i s Streptognathodus postfusus

Shikhansky

1 Streptognathodus S. c o n s t r i c t u s

L

fusus

o

S. c r i s t e l l a r i s o

S. i s o l a t u s

Fig. 2. Permian East-European traditional scale.

3~"T"

~

20

LEGEND

Litholol~ic S ~ m b o l s

~~]

Limestone

~

Siltstone

Marl

~

Sandstone Conglomerate, Gravelstone

Reef

[~]

Dolomite

~

Volcanic Rocks

Evaporite

~

Tuffs

Clay, Shale

I"~'i~'~''l T i l l o i d

Special Symbols m

Sulphate - Carbonate

Coal Phosphate Glauconite Redbeds

Palaeontological Symbols 9

Foraminifers Fusulinids R u g o s e coral ;~ Bryozoan 9~ , B r a c h i o p o d s ]~y B i v a l v e s

~ ~ ~=~ ,.)~ ~ ~,

Ammonoids Fillopods Ostracods Tetrapods Conodonts Fishes

~. .'~ 9/~ ,t~ ~ ~

Conularia Insects Algae Stromatolites Macroflora Miospores

It is very difficult to agree with the first viewpoint because the paleomagnetic evidence indicates that the Tatarian Stage corresponds to a little more than two stages of the Tethyan scale [3]. The second viewpoint is rather interesting and requires additional consideration. Nevertheless, without doubt the Tatarian requires subdivision, which has been repeatedly mentioned [5, 6]. Furthermore, the lower boundary of the Triassic is drawn now at the base of the Otoceras woodwardi Zone of marine sections and the synchroneity of this level has not been demonstrated. The boundary between the two series of the East-European scale is drawn at the base of the Ufimian or the Solikamsky Horizon. However, there are serious evidences that confirm the assignment of the latter to the Kungurian. Recent finding of the Kungurian ammonoids Epijuresanites vaigachensis Bogoslovskaya and Epijuresanites sp. nov. in the equivalent of the Solikamsk Horizon in the Lekvorkutskaya suite of the Pechora basin and in the Tabjuskaya suite of the Pai-Khoy [7, 8], confirm a Kungurian age of these deposits. The representative Kungurian genus Tumaroceras is known from the uppermost part of the Tumarinsky Horizon in Verkhoyanye (Table 1), which is overlain by the Delenzhinsky Horizon with the Roadian ammonoid assemblage (Daubichites, Sverdrupites, Pseudosverdrupites ) [9]. Thus, it is necessary to assign the Solikamsky Horizon to the Kungurian. Stages of the East-European scale above the Artinskian, established exclusively on a lithological basis, do not conform to modern international requirements, and call for

21 improvement and definition of the lower boundaries. The first step in this direction has already been made. The lower boundary of the Kungurian has been lowered to the base of the Saraninsky Horizon and been made coincident with the base of the Neostreptognathodus pnevi conodont zone. This enables a reliable definition of the lower boundary of the stage and retains it as a standard unit, because the lower boundary of the N. pnevi Zone can be traced in all the realms. The Upper Permian stages established in the Volga and Kama area are composed of alternating continental, lagoonal and marine deposits that do not fully conform to the international requirements and cannot claim to be the global standard. Abrupt changes in the character of sedimentation at their boundaries interfere with the reconstruction of successive evolutionary changes in faunal groups, which rules out the possibility of providing reliable definition and tracing the boundaries. Detailed study and subdivision of the most complete, paleontologically well-defined Biarmian sequences will doubtless promote the improvement of the East-European scale, and aidsin the definition of the stage boundaries and retention of nomenclature of the Upper Permian stages. Such sequences are primarily the sequences of the Kolyma-Omolon Subrealm. The regional scale of this subrealm is based on a series of deposits of different facies of the continental slope, in piedmont, shelf to island [ 10]. The scale reflects the geological history of the Permian basins. Redeterming boundaries of different orders, revealed on the basis of synthesising sedimentological and paleontological evidence, were the basis for the distinguished units. The Permian System in this scale is subdivided into two series, five regional horizons and sixteen assemblage zones (figs. 3, 4). Integration of geological, sequence-stratigraphical and event- stratigraphical data enable the recognition of a number of reference correlation levels in this scale, associated with major biotic changes and resulting from eustatic sea level fluctuation. Thus, the Munugudzhaksky/Dzhigdalinsky Horizon boundary is rather well traced within the entire Biarmian Realm and is characterized by essential biotic changes [ 11, 12]. In the type area of the Permian System it corresponds to the second half of the Artinskian and is characterized by the Middle Artinskian event [ 13]. The very important Dzhigdalinsky/Omolonsky boundary is characterized by appearance of the Roadian ammonoid assemblage and is recognized within the entire Biarmian realm from Verkhoyanye to Novaya Zemlya. In the latter region it is drawn between the Belushinskaya and Kocherginskaya formations (Table 1). In Western Verkhoyanye this level is established between the Tumarinsky and Delenzhinsky Horizons [ 11, 14]. The deposits with Daubichites and Sverdrupites formed under a clearly expressed transgressive environment (fig. 5). The comprehensive analysis of the Middle Permian event that was repeatedly characterized enable the tracing this level on a global scale (Table 1). In the East-European scale this level corresponds to the Solikamsky/Sheshminsky Horizons of the Ufimian [9, 10, 11 ]. This level is the most natural boundary of two series in traditional scale. Conodonts have been found within the well-studied Kazanian Stage [ 15], which allow correlation of the Kazanian with the Wordian of Texas. The Tatarian is currently adeqately studied and subdivided into zones based on freshwater ostracods, bivalves, vertebrates [4, 16]. Detailed fish faunal assemblages have been recognized [16]. Macroflora and miospores have been also studied in detail [16, 17].

22

Horizon

Zone

Khivachsky

S. p a r a c u r v a t a

Gizhiginsky

C. obrustschewi

Lithology Biota ~ . . . . ~ . "_' " ~

c rvo,

-~.,,

-

-

1

M a g a d a n i a bajkurica

_t__.__~._ =~--L-..-r;

Terrakea korkodonensis ~

Omolonsky

Terrakea borealis

~

Omolonia snjatkovi

_~

M o n g o l o s i a russiensis

C2)

.0

l i.

!

~ I

I

I

A

Kolymaella ogonerensis i--.-- . - ~ ~ -

-

~

! '~g

.

o ,..~

~

Megousia kuliki

s

_

Anidanthus aagardi

~

.

i

9 !

Jakutoproductus

i

burgalensis

"~a ~ * t o l

Jakutoproductus rugosus Jakutoproductus terechovi

" ." ." ." . . -.~. ."... ~ d_ ~ - J ~

9

~

~

"D

~)

~3

Jakutoproductus verchoyanicus

" ~" ~" ~" " . - -

Jakutoproductus expositus

~. ~. ~. ~ ~. "_ ", : " . ~ _ _

9

"~

,

~

o

~

~

~

~

Fig. 3. Regional stratigraphic scale of the Kolyma-Omolon Province. The paleomagnetic data is also very important [ 16, 18]. Synthesis of recent evidence creates the prerequisites not only for detailed remote interregional correlations, but also for correlations with Gondwana and even Tethys sequences [4]. The available data indicate the necessity in dividing the Tatarian into a number of stage subdivisions as has been implied earlier [5]. A fundamental change of biota at the base of the Severodvinsky Horizon of the Tatarian has been repeatedly recorded. This level is also associated with the Kiaman/Illawarra paleomagnetic boundary. This is one of the most important geomagnetic marks that enable an intercontinental correlation.

23

u~ ~D

o

Foraminifer Zone

o

'~, ~ ,~ Brachiopod Zone mN~, I

I

Bivalve Zone

Ammonoids

l

l

I

.=- ~ ..~ jo ~

Stepanoviella paracurvata

Intomodesma costatum

Frondicularia maxima

Maitaia tenkensis Cancrinelloides curvatus

c...) ,~

=

Maitaia bella

'-- - ,-'~ Cancrinelloides obrutschewi

= ~~ ,-

r.~

|~

o

Frondicularia planilata

'

= Terrakea borealis o Omolonia snjatkovi Mongolosia russie nsis Kolymaella ogonerensis ,

i-.

9

m - i

,~ ~ ~ ~ "~ ,.~

i~ ".= , o 1 =~ ~, ~ .

Kolymia plicata

,

Anidanthus aagardi Jakutoproductus burgalensis ' Jakutoproductus rugosus Jakutoproductus terechovi Jakutoproductus verchoyanicus Jakutoproductus . expositus I

Kolymia multiformis

Frondicularia elongata

Kolymia inoceramiformis Frondicularia gane l inae

Aphanaia dilatata

Frondicularia . Aphanaia andrianovi prima

Megousia kuliki

e~o

9 .

Merismopteria permiana

Magadania bajkurica Terrakea korkodonensis

..~

=

Glyptoleda borealica

Frondicularia co mposi ta

Frondicularia zavodovskyi I

Sverdrupites harkeri

Epij'uresanites musalitini

Aphanaia lima I

I

Edmondia nebrascensis Protonodosaria and small Frondicularia . Tolypammina confusa and small Protonodosaria

"~

Neoshumardites triceps Paleoneilo parencia

Fig. 4. Zonation scheme of the Permian of the Kolyma-Omolon Province.

I

24

Table 1 Correlation chart of the Permian reference sections in the Biarmian Realm. Chronostmti graphic Scale (36)

Pechora Province Novaya Zemlya Province East-European Scale ' Karskaya Severo- 1 BarentsovKarskaya Zona Pechorsk Zona skaya Zona , Zona ' ' 1 Valentinov~ Vyatsky ,,-" Shadrovskaya !m-./.," skaya ~9 ~ Severodvinsky ~ .,," NeogeoSavinskaya !.~. , i

,

I

/

./

./

/

=~

!

Urzhumsky

ceras

Silovskaya

,

E

,.-.-.l

~ ~

,

Nemdinsky . Povolzhsky

,~.~

.

Gerkinskaya

Erjagin. Seidinskaya skaya

Sheshminsky

O

~inozemel Sverdrupites skaya Kocherginskaya Sverdrupites

Tabjuskaya

Solikamsky

g

=

Irensky

'g

Filippovsky

Epijuresa - ~~~, nites

i~

T~k~ro-

i~0

r.~

Liurjagin-

9

~5 = =

i

Sar~nsky ~rginsky

e .-~e< i<

Btmsevsky

~, 9

~ Sterlitam~ky

I~

~

'~

,~ i

i

= =

m

i

Talatin-

Samn~ky 9

<,

I,

Tastubsky

in

~

Belushinskaya

Sokolovskaya

Sokolovskaya

audnitskayi

ceras

skaya

.

Belushinskaya

Shikhansky

~ Kholodnolozhsky ,<,

skaya

Aj achyaginskaya

J

Talatinskaya Belkovskaya Gusinaya

Yunyaginskaya Sezymskaya

25 Kolyma-Omolon Province ,.~

Verchoyanye-Okhotsk i Province

Stepanoviella paracurvata

rIl

Transbaikal Province

Angarida

Khalpirskaya Fm

Tailugansky Zabaikalsky Horizon Gramoteinsky

,..M

..~ = "~0

Cancrinelloides curvatus

~ ~ "~ ~0

Kingoceras?

Cancrine llo ides obrutschewi Magadania bajkurica Terrakea

o .. o

korkodonensis Terrakea borealis

;~

.m o~t)

Timorites

Leninsky Cancrinelloides obrutschewi

Cancrine llo ides obrutschewi = s ~ .ZZ .

Olgerdia zavodovsky

;

Magadania bajkurica

~~

Terrakea korkodonensis

Uskatsky

Kolymia plicata Kazankovomarkinsky

, ,..~ r,r

= o

Omolonia snjatkovi '

Mongolosia russiensis

i~' -~ ~

Mongolosia russiensis Sverdrupites

o= N "~ o

Kolymaella ogonerensis Tumaroceras

Alentuisky Horizon

Mitinsky Starokuznetsky

Sverdrupites = ON 9= o ZZ

Kolymaella ogonerensis Megousia kuliki

~

Megousia kuliki

Epij'uresanites

.-

Epijuresanites

" ,"~

"~

Jakutoproductus burgalensis o ~~

Jakutoproductus rugosus

ZZ~, Jakutoproductus terechovi

Jakutoproductus ex gr. verchoyanicus ~ ~

Jakutoproductus verchoyanicus

"~ =

Jakutoproductus verchoyanicus Jakutoproductus

~ .~ i 0

expositus

o

Kizhimginsky Horizon

i

Jakutoproductus protoverchoyanicus J. expositus

Kemerovsky Ishanovsky

~ ~ x:

"~

~o~ "~ l

~ ~ ~"

bq

,

N

Usyatsky

~

~

o .,..a N

(D

o

26

9

'

9~ i~

Brachiopod Zone

Ammonoids

/

r

"-6 .~-

..~

i

.

.

,

.

=

,

~

~

[._,

9~-

:~

~~ ,'~ ~o ~

C3

,

:}~~~~) Sverdrupites harkeri Daubichites Anuites

'~zl

--- " --,:t~at,'-"

~

Kolymaella ogonerensis =

~ ""=

"r. = = =

Tumaroceras kaschirzevi

-.-, Y. .~~ ,m_. . - .

Beraioceras stepanovi

.~ fi ~. = ~ ~ =~

Megousia kuliki

Epijuresanites musalitini Tumaroceras yakutorum

~

l~

~

""

~

I

I

!

I

I

verchoyanicus = ~

~

= ~

.~.=

~

.=-~,

= .~.

.~

Ura/oceras p o p o w i Tumaroceras subyakutorum Neoshumardites triceps

Jakutoproductus verchoyanicus

= .~

r~..~ - . . . .

;-_"~."_ _-, ~., ~-'-"- B

Metalegoceras

....

Preshumardites

~" ,_-~', ~ "

~

,

~,

~ ~

1

| o n

i Jakutoproductus ex gr.

.~.=

~

:.:..;z.:

Mongolosia russiensis .~

I

: ~ ' 1

;~'~'"Terrakeak~176176

~

~,~..,,....~,

j[~,, ,~j

:LO,ID,J~,

obrutschewi Olgerdia zavodovsky

=

,

Kingoceras? Mexicoceras

Cancrinelloides

~

j~

.

Jakutoproductus protoverchoyanicus

Bulunites juferevi

,

,

,

~ ,

"L-4-.'~. 9

[i~

~r

<~

<

. ,~

~~

Somoholites

,

,

,

.. . . .

o

~,~ - - ~,, J. exposit~.~'s |

,

,

Neopro

jl~Orites

.- --~ ," _~j,..~:j......~_,

.

Fig. 5. Regional stratigraphic chart of the Permian of the Verkoyanye-Okhotsk Province.

27 3. Angarida Permian sediments are subdivided into two major cycles. The earlier one completes the regression of the Carboniferous Period, the latter one corresponds to the Late Permian cycle proper. Its beginning - Early Pelyatkinsky or Late Kemerovsky time, is associated with the disappearance of coal deposits (fig. 6). The end of the Permian is characterized by the first appearance of trap volcanism which is wide-spread even in Triassic. Plant associations belong to the Cordaites assemblage that appeared in the Carboniferous. Systematic composition of the flora throughout the Permian Period changed slowly and gradually. The strongest changes in flora evolution occurred at the boundary of Usyatsk/Starokuznetsk time and show up as replacement of the Late Balakhonian-type by the Kolchugian-type. At this level callipterids and psigmophylls appeared and small-leave Cordaites and Rufloria became predominant. 4. Permian of the Tethyan Realm The Tethyan scale used in Russia has been constructed exclusively in marine sequences and is a widely developed biozonal scale based on fusulinids [ 19]. The Permian deposits of the Tethyan Realm are subdivided into two series, nine stages and 20 zones (fig. 7). The lower boundary of the Permian System is drawn at the same level as in the EastEuropean scale. The boundary between series is established at the base of the Kubergandinian and it corresponds to the middle part of the Ufimian, to the base of the Sheshminsky Horizon. The upper boundary is drawn at the top of the Dorashamian Stage in the Transcaucasus stratotype and it is noted below the appearance of Hindeodus parvus. The use of fusulinids exclusively, their frequent reworking, and an insufficiently reliable correlation with ammonoid and conodont assemblages or single occurrences has caused some serious errors. It should also be mentioned that the stratotypes of some Tethyan stages are not well chosen, their boundaries are not sufficiently defined (the Yakhtashian, Murgabian, Midian) due to which the scopes of the stages have been changed repeatedly

[20]. The Asselian and Sakmarian of the Tethyan Realm are the same as in the East-European scale. The lower boundary of the Yakhtashian is not well defined and its occurrence within the CIS is limited only to the Darvaz (Central Asia). The stage is subdivided into two fusulinid zones: Chalaroschwagerina solita and Ch. vulgaris. It apparently corresponds to the upper part of the Longlinian Stage of China and some part of the Artinskian. The Bolorian is subdivided into two fusulinid zones: Brevaxina dyhrenfurthi and Misellina parvicostata, and is ubiquitously distinguished within Russia and the CIS. The Bolorian transgression starts the transgressive-regressive cycle. The fusulinid characteristic of the stage is supplemented by ammonoids and conodonts of the Kochusuyskaya Formation in the Southeastern Pamirs [21, 22]. The Kubergandinian is also subdivided into two fusulinid zones: Armenina, Misellina ovalis and Cancellina cutalensis. Its lower boundary is characterized by the appearance of the Roadian ammonoid assemblage [ 1, 23], and it is recognized in most sections of the Tethyan Realm.

28

O'l

m

Horizon

o

o

"~

Horizon

~

o

,,..~

J ,

, --~ 9 ~.-

Gagaryeostrovsky

..

~.~

9 _.._.~, . . _ ~ ~

Tailugansky

---" 1

PI

"--~s Ik'~

Gramoteinsky

_,_.

X

.n o

";L_

.,--==,

T

-:71

13

Leninsky

Degalinsky . . . .

-~ o el

Kazankovomarkinsky

r/l

X ;

:

:

1~

--=-'-'-'-'-'-'-'--~--- -' .

r-,

:-,

,

,.

.

"!-

~r

o--

M

Z--.2":

. . . . . . . . .

X v

~-:13

Mitinsky

.L...FI . . . .

.,,~.-~: --.-~. -

Uskatsky Upper

Lower

~---.~_"

Starokuznetsky -,--~-~ l~ 9

___

J~

.

B

~

_ . . . . ~ . . . . . . 9

.

,

Usyatsky Upper

.

.

.

.

.

X

Ishanovsky .

9

, :

-- --

1~ "

c~

92"i"

~

. . . . .

.

O

....

m

9

,,,,

,

9

,

O

,

9

9

D4*

.

rur~

o~

.

Promezhutochny ~ ,

Lower

...,,

4~,

<

•

!

x ~ -~ 13 "~

,~,

m ~D r/l

-

.

-~-,-

r/l

~

.

, '-" _

- -I I

Kemerovsky

~_~_.----Z._ 13

.

"- ''

,.',"

-,-

, . D , .

m..

,"

-,v

9....~ i ~0

oO

Fig. 6. Regional stratigraphic chart of the Permian of the Angarida.

Q,,)

29

Tethyan stratigraphic scale

Chronostratigraphic scale (36) Conodont zones

Stage

Zone

c.~

Clarkina changxingensis "~o ~

Dorashamian

Pleuronodoceras occidentale Phisonites triangulus

C. subcarinata

~

o

Vedioceras ventroplanum

,~ r

C. orientalis

~:

C. postbitteri

Araxoceras latum

Jinogondolella altudaensis

Lepidolina

.,.a

g~ L)

Dzhulfian

J. postserrata

Midian

Yabeina Neoschwagerina margaritae

Jinogondolella aserrata Murgabian

Neoschwagerina craticulifera Neoschwagerina simplex

Jinogondolella nankingensis

Kubergandinian

Cancellina cutalensis Armenina, Misellina ovalis

o

Misellina parvicostata

Mesogondolella idahoensis . ,..~

~ Neostreptognathodus pnevi ~o

Bolorian

Brevaxina dyhrenfurti

N. exculptus Chalaroschwagerina vulgaris

N. pequopensis .,..~

Sweetognathus whitei

Yakhtashian

Chalaroschwagerina solita

. ,...~

<

M. bisseli Robustoschwagerina

S. primus Sakmarian

r//

Streptognathodus postfusus

Paraschwagerina

S. constrictus

Schwagerina sphaerica Pseudofusilina firma

~ ,..~

Asselian

<

S. isolatus

Schwagerina moelleri Pseudofusulina fecunda Schwagerina vulgaris Schwagerina fusiformis

Fig. 7. Correlation chart of the Permian sections in the South Russia and the CIS.

30

Transcaucasus Horizon

Far East

South-East Pamirs Horizon

-~

i

.l..a o,., _

! ,

.

Horizon

o

E

i

-2---.'-:--~ D o r a s h a m s k y--__--__~

Takhtabulak 1"~~2,, Lyudyanzinsky ~

Dzhulfinsky

Kutal I"

I

!!!

Khachiksky

g

!

Chandalazky

!

Arpinsky Gnishiksky Asnyisky

Karasin

~

Deira Dzhamantal

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.

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z cl

31 The Murgabian was originally established as the "horizon" with advanced fusulinids [24], comprising the Yabeina-Lepidolina Genozone. Later, the Murgabian has been accepted following E. Ya. Leven [25] as the Neoschwagerina Genozone, subdivided into the zones of N. simplex below, N. craticulifera and N. margaritae above. The Yabeina-Lepidolina Genozone separating the Murgabian from the Dzhulfian was named as the Midian. However, the lower boundary of the Murgabian in the strototype was drawn at the top of the Kubergandinian Formation comprising in its upper part the Neoschwagerina simplex Zone. Accordingly the Murgabian lower boundary in the stratotype was defined by the appearance of Neoschwagerina craticulifera and the scope of the stage was only limited by the N. craticulifera and N. margaritae zones. Joint occurrence of N. margaritae with Yabeina and Lepidolina directly above the N. craticulifera Zone in the most complete Tethyan sequences supports assignment of the N. margaritae Zone to the Midian [20, 26]. Therefore, the scope of the Murgabian is under discussion and must be currently restricted by the one or two fusulinid zones. The Midian consists of the Neoschwagerina margaritae Zone and Yabeina-Lepidolina Genozone. As to the Lepidolina kumaensis Zone, its position is debatable and it might corresponds to the lower part of the Wuchiapingian. It should also be noted that in some regions of the Tethyan Realm the richest Wordian ammonoid assemblages are recorded [20, 27] along with fusulinids and small foraminifers of the Neoscwagerina margaritae Zone of the Lower Midian, whereas the Upper Midian yields Capitanian ammonoids [28]. The Dzhulfian was established on the basis of ammonoids and subdivided in detail [29, 30]. The correspondence of its lower boundary to the Wuchiapingian boundary is debatable. Possibly it corresponds to the middle part of the latter. Besides in the Transcaucasus, this stage is also recognized in Central Asia (Kutal unit) and in the Southem Primorye (the lower part of the Lyudanzinsky Horizon). In addition to the Transcaucasus the Dorashamian (Changhsingian) has been reliably established for the first time in Southern Primorye on the basis of ammonoids [31 ]. The latest studies have revealed the presence of Changhsingian (maybe Upper Changhsingian) deposits in the Southem Pamirs and Northwestem Caucasus [32, 33]. In Central Asia the Changhsingian is mainly based on conodonts and small foraminifers of the Colaniella parva Zone. In the Northwestern Caucasus a representative of Dushanoceras has been found that enable correlation of the deposits with the Rotodiscoceras Zone in Southern China. Bivalves (Claraia caucasica Kulikov et Tkachuk and Claraioides aff. C. dianus Guo) co-occur with ammonoids. Along with ammonoids the Northwestern Caucasus deposits also contain the Late Changhsingian assemblage of small foraminifers of the Colaniella parva Zone, fusulinids of the Palaeofusulina sinensis Zone and Changhsingian brachiopods [33]. The only representative of tetracorals - Waagenophyllum asperum Zhao (identified by O. L. Kossovaya) is also characteristic of the Changhsingian in China [34]. Macroflora is represented by the Zechsteinian and Changhsingian species Ulmannia bronni Goepp. and Pseudovoltzia liebeana (Geinitz) Florin. Therefore, one might assume that the uppermost Permian beds occur in most of the southern regions of Russia and the CIS - the Northwestern Caucasus, Transcaucasus, Southeastern Pamirs, and Southem Primorye. At the same time it is impossible to rule out the presence of breaks at the base of the Changhsingian and in the lower Upper Permian horizons. Thus, in the Southeastern Pamirs sequences that were previously regarded as continuous, there are apparently no Upper Midian and Lower Changhsingian deposits. The completeness of the Dzhulfian deposits has not been proven. It is should be noted that the Subcommission on Permian Stratigraphy has formally decided a tripartite subdivision of the Permian and has proposed a new chronostratigraphic

32 scale that can be used for marine reference successions of the Tethyan Realm. 5. Correlation

The lower boundary of the Permian System is rather easily traced within almost the entire East-European Subrealm and in most of the Tethyan Realm due to appearance of the characteristic assemblage of fusulinids. Its position is less definite in sections of the Taimyr-Kolyma Subrealm that contain no fusulinds. Here, the base of the Permian is conditionally correlated with the base of the Munugudzhaksky Horizon (Table 1). In the Angarida the lower boundary is drawn at the base of the Promezhutochny Horizon. The Asselian/Sakmarian boundary is clearly marked by fusulinids, ammonoids or conodonts in the East-European and Tethyan realms, but cannot be drawn in the TaimyrKolyma Subrealm and in the Angarida. The Lower Artinskian boundary is marked by the appearance of the ammonoids Neoshumardites, Uraloceras, Paragastrioceras etc. within the Biarmian Realm, and in the Kolyma-Omolon Province it is drawn at the base of the Jakutoproductus rugosus Zone within the Munugudzhaksky Horizon. However, in the Verkhoyanye-Okhotsk Province it corresponds to the base of the Sterlitamaksky Horizon of the Sakmarian [ 14]. Significant differences between fusulinids of the Yakhtashian and Artinskian make it difficult to precisely draw this boundary in the Central Asia of the Tethyan Realm. The Lower Kungurian boundary can be recognized by the appearence of the conodont Neostreptognathodus pnevi and also on the basis of an intermediate ammonoid assemblage between Late Artinskian and Roadian. This assemblage corresponds to the Irensky and Solikamsky Horizons of the East-European scale. It can be traced extensively in the Biarmian Realm. The most characteristic genera are Epijuresanites, Tumaroceras, Baraioceras. Recently representatives of Epijuresanites were discovered in some sections (equivalents to the Solikamsky Horizon) of Biarmian Realm [7, 9] and Southern Primorye of the Tethys [3 5]. In the Central Asia Province of the Tethyan Realm the Bolorian ammonoid assemblage can be reliably correlated with the Kungurian one because they have a similar stratigraphic position between the Upper Artinskian and Roadian [21 ]. As noted above, the Kungurian ammonoid assemblage is apparently not restricted to the Kungurian, but also continues into the Lower Ufimian. That is why the level of the appearance of the Roadian ammonoid assemblage clearly displayed in both the Biarmian and Tethyan realms corresponds to the Sheshminsky Horizon of the Ufimian. In the Taimyr-Kolyma Subrealm it is confined to the base of the Mongolosia russiensis Zone, and in the Tethyan Realm to the base of the Kubergandinian. There is no direct evidence for correlating the Kazanian outside the East-European Province. However, it might be presumed that the most upper part of the Omolon Horizon of the Taimyr-Kolyma Subrealm and the Murgabian Stage of the Tethys correspond to the Kazanian (fig. 7, Table 1). There is no reliable evidence for tracing the Lower Tatarian boundary. The base of its upper substage (the Severodvinsky Horizon), connected with the Kiaman/Illawarra hyperzone boundary, is correlated more definitely. In the Kolyma-Omolon Subrealm it is drawn within Gizhiginsky Horizon at the base of the Cancrinelloides curvatus Zone. The Angarida floral assemblages of this boundary are marked by disappearance of Rufloria representatives in the East-European sections and diversity of the genus Tatarina. In the Tethyan Realm this boundary is drawn in the Middle Midian, at the top of the Neoschwagerina margaritae Zone. This correlation is confirmed by biostratigraphic dat~ [11 ].

33 6. Discussion

The Subcommission on Permian Stratigraphy has compiled and adopted the chronostratigraphic chart assuming the tripartite subdivision into series [36]. These are the Cisuralian, Guadalupian and Lopingian Series and their constituent stages standardized respectively in the Urals, Southwest USA, and South China, for the Lower, Middle and Upper Permian. Despite the fact that not all the stages of the Guadalupian and Lopingian can be recorded in the Biarmian Realm, certain levels are established with a sufficient degree of confidence. This is primarily, the lower Roadian boundary that is recognized by the appearance of the Roadian ammonoid assemblage - Sverdrupites, Daubichites. It is quite possible that the lower Capitanian boundary corresponds to the base of the Severodvinsky Horizon of the Tatarian Stage, because of the recognition of the Illawarra Magnetic Reversal near the base of the Capitanian and in the middle part of the Tatarian Stage (fig. 8). At the same time, stage boundaries of the chronostratigraphic scale are characterized exclusively by conodonts, in fact cannot be drawn precisely in Boreal sections. Therefore, it seems necessary to use physical, chemical, radiometric and paleomagnetic indicators, to supplement biochronological criteria, for drawing and tracing the boundaries. 7. Conclusions

1. Two parallel scales of the Permian system- the traditional East-European (Biarmian) and the Tethyan ( near-equatorial ) are currently used in Russia and the CIS. 2. The East-European scale in the upper part does not conform to modern international requirements and at present cannot claim to have the status of a global standard. 3. Significant success has been attained in the studies of the Upper Permian stratotypes on the Russian Platform providing data on the most complete reference sections of the Biarmia, and has resulted in the necessity of improving the East-European scale: more precise drawing of stage boundaries and providing definitions for them, and changing the scope of some stages. 4. The most acceptable scale based on marine sections with the stage boundaries confirmed by conodonts and ammonoids, is the scale reccomended by the Subcommission on Permian Stratigraphy. 5. The integrated chronostratigraphic scale that has been proposed by the SPS can be used in the Tethyan Realm. 6. So far as the scale based on marine sections cannot be used for wide-spread continental sediments of the Biarmian Realm, Russian geologists propose the parallel use of both. Acknowledgements

I am grateful to many collegues for their help and field companionship. I am especially thankful to Prof. Yin Hongfu for financial support of my participation in different International Conferences, and in a field excursion in the Northwestern Caucasus. My cordial thanks to Dr. J. M. Dickins for critical readings of the manuscript, careful review and helping to improve the English text. I thank also Mrs. T. I. Vasilyeva for English translation.

34

References 1.

2.

3.

4. 5. 6.

7. 8. 9.

10. 11. 12. 13.

14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26.

V.G. Ganelin and G.V. Kotlyar, Zonation of the USSR territory and a general characteristic of Permian system, in: Main features of Stratigraphy of Permian system in the USSR, G. V. Kotlyar and D. L. Stepanov, eds., Trans., vol. 286, new ser., (1984), 279 p. V.I. Davydov, B.F. Glenister, C. Spinosa, S.M. Ritter, V.V. Chernykh, B.R. Wardlaw and W.S. Snyder, Proposal of Aidaralash as Global Stratotype Section and Point (GSSP) for base of the Permian System, Episodes, vol. 21, N 1, (1998), 11-18. V.R. Lozovsky, Correlation of the Permian-Triassic boundary beds in the continental and marine sections, in: V.R. Lozovsky and N.K. Esaulova, eds., Permian-Triassic boundary in the continental series of East Europe, Moscow, (1998), 210-216. V.K. Golubev, Correlation of the Upper Permian of East Europe and Tethys, in: Upper Permian Stratotypes of the Volga Region, Abstracts, Kazan, (1998), 56-57. V.I. Rozanov, The Dvinian stage as a new subdivision of the Upper Permian of the North of the European part of Russia, XIII Intern. Congress on Carb.-Permian, Abstracts, Krakow, (1995), 123. G.V. Kotlyar, Major problems of further study of the Upper Permian, in: Stratotypes and Reference sections of the Upper Permian in the Region on the Volga and Kama Rivers, N.K. Esaulova and V.R. Lozovsky, eds., Kazan, (1996), 507-513. M.F. Bogoslovskaya, Permian ammonoids from Pai-Khoy and Vaigach Islands, Paleontol. J., N 6, (1997), 23-28. V.A. Guskov, S.K. Pukhonto and N.E. Yatsuk, Upper Permian of the Northeastern Pai-Khoy, Sovetskaya geol., N 2, (1980), 68-75. I.V. Budnikov, V.E. Sivchikov, A.G. Klets and R.V. Kutygin, Ufimian stage in the Siberia and Verkhoyanye sections, in: Upper Permian Stratotypes of the Volga Region, Abstracts, Kazan, (1998), 20-21. V.G. Ganelin, A.S. Biakov and N.I. Karavaeva, Permian stratigraphy scale of the Northeastern Asia, Ibid., (1998), 49-50. G.V. Kotlyar, Correlation Reference levels of the Permian System, Stratigraphy. Geol. correlation, vol. 5, N 2, (1997), 35-50. E.Ya. Leven, M.F. Bogoslovskaya, V.G. Ganelin, T.A. Grunt, T.B. Leonova and A.N. Reimers, Reconstruction of the marine biota in the Middle Lower Permian, Ibid., vol. 4, N 1, (1996), 61-70. O.L. Kossovaya, E.A. Guseva, A.V. Zhuravlev and A.E. Lukin, The Middle Artinskian event manifestation, scale, correlation, in: Biostratigraphy and Ecological-Biospherical aspects of the Palaeontology, Abstract, St. Petersburg, (1998), 53-54. A.G. Klets, I.V. Budnikov, R.V. Kutygin and V.S. Grinenko, Permian Stratigraphic Units of the WesternVerkhoyansk Mountains and Their Correlation, Permophiles, N 32, (1998), 8-9. V.G. Chalymbadja, Conodonts, in: Stratotypes and Reference Sections of the Upper Permian of the Kazan Region, B.V. Burov and V.S. Gubareva, eds., Moscow, (1998), 36-39. N.K. Esaulova, V.R. Lozovsky and A.Yu. Rozanov (eds.), Stratotypes and Reference Sections of the Upper Permian in the regions of the Volga and Kama rivers, Moscow, (1998), 300 p. A.V. Gomankov and S.V. Meyen, Tatarina flora (composition and distribution in the Late Permian of Eurasia), Moscow, (1986), 174 p. E.A. Molostovsky, The paleomagnetic stratigraphy of the Upper Permian and Triassic of the east of the European part of the USSR, Saratov, (1983), 167 p. E.Ya. Leven, Explonation note to the Permian Stratigraphic Scale of the Tethyan Realm, Leningrad, (1980), 50 p. G.V. Kotlyar and G.P. Pronina, Murgabian and Midian Stages of the Tethyan Realm, Permophiles, N 27, (1995), 23-26. T.B. Leonova and V.Yu. Dmitriev, Early Permian ammonoids of the Southeastern Pamirs, Moscow, (1989), 198 p. H. Kozur, Die Conodontenchronologie des Perms, Freiberg. Forschung, C 334, (1978), 85-161. I.O. Chedija, M.F. Bogoslovskaya, V.I. Davydov and V.Yu. Dmitriev, Fusulinids and ammonoids in the Kubergandinian stratotype (Southeastern Pamirs), Annual Paleont. Soc., Leningrad, (1986), 28-53. A.D. Miklukho-Maklay, Stage subdivision of the marine deposits of the south regions of the USSR, Dokl. Akad. Nauk SSSR, vol.120, N 1, (1958), 175-178. E.Ya. Leven, Permian Stratigraphy and Fusulinids of the Pamirs, Moscow, (1967), 224 p. E.Ya. Leven, Permian Midian stage and its boundaries, Stratigraphy. Geol. correlation, vol. 4, N 6,

35

(1996), 20-31. 27. H. Kozur and V.I. Davydov, The importance of the Permian of the Sosio Valley (Western Sicily, Italy) for Guadalupian Stratigraphy, in: Guadalupian II, Abstr. and Proceed. of the second Guadalup. Symposium, Alpine, (1996), 11-15. 28. G.V. Kotlyar, Yu.D. Zakharov, L.I. Popeko, J. Tazawa and V.I. Burago, Strata with Timorites in the East Asia. Geol. of Pac. Ocean, vol. 16, N 3, (1997), 41-50. 29. V.E. Ruzencev and T.G. Sarycheva (eds.), Development and change of the marine biota on the Paleozoic/Mesozoic boundary, Moscow, (1965), 430 p. 30. G.V. Kotlyar, Yu.D. Zakharov, B.V. Koczirkevicz, G.S. Kropatcheva, K.O. Rostovcev, I.O. Chedija, G.P. Vuks and E.A. Guseva, Evolution of the Latest Permian Biota. Dzhulfian and Dorashamian Regional stages in the USSR, Leningrad, (1983), 199 p. 31. Yu.D. Zakharov, A. Oleinikov and G.V. Kotlyar, Late Changxingian ammonoids, bivalves, and brachiopods in South Primorye, in: J.M. Dickins, ed., Late Palaeozoic and Early Mesozoic CircumPacific Events and Their Global Correlation, Cambridge Univ. Press, (1997), 142-146. 32. T.G. Ilyina, Distribution, Taxonomy and Morphology of Permian Rugosa of Southeastern Pamirs (Tadzhikistan), Bol. Res. Soc. Esp. Hist. Nat. (Sec. Geol.), N 1-4, (1997), 127-140. 33. G.V. Kotlyar, Yu.D. Zakharov and G.P. Pronina, Changhsingian deposits of Russia, in: Upper Permian Stratotypes of the Volga Region, Abstract, Kazan, (1998), 82-84. 34. V. Ezaki, Patterns and paleoenvironmental implications of end-Permian extinction of Rugosa in South China, Palaeogeogr. Palaeoclimat. Palaeoecol., vol. 107, (1994), 165-177. 35. Yu.D. Zakharov, A.V. Oleinikov, G.V. Kotlyar, V.I. Burago, V.S. Rudenko and E.A. Dukhovskaya, The first find of Early Permian goniatite in South Primorye, Geol. Pacif. Ocean, vol. 14, N 5, (1997), 116122. 36. J. Yugan, B.R. Wardlaw, B.F. Glenister and G.V. Kotlyar, Permian chronostratigraphic subdivisions, Episodes, vol. 20, N 1, (1997), 10-15.

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Persian-Triassic Evolution of Tethys and Western Circum-Pacific H. Yin, J.M. Dickins, G.R. Shi and J. Tong (Editors) 9 2000 Elsevier Science B.V. All rights reserved.

37

PERMIAN OF SOUTH EUROPE AND I T S I N T E R R E G I O N A L C O R R E L A T I O N G.CASSINIS a, P.DI STEFANO b, F.MASSARI c, C.NERI d, and C.VENTURINI e a Dipartimento di Scienze della Terra, Universit~ di Pavia, Via Ferrata 1, 1-27100 Pavia, Italy b Dipartimento di Geologia e Geodesia, Universit~t di Palermo, Via E.Toti 91, 1-90128 Palermo, Italy c Dipartimento di Geologia, Paleontologia e Geofisica, Universit~ di Padova, Via Giotto 1, 1-35137 Padova, Italy d Dipartimento di Scienze Geologiche, Universi~ di Ferrara, Corso Ercole I d'Este 32, 1-44100 Ferrara, Italy Dipartimento di Scienze della Terra e Geologico-Ambientali, Universit~ di Bologna, Via Zamboni 67, 1-40127 Bologna, Italy

e

This contribution is a synthesis of knowledge about the Permian of South Europe, which mainly consists of continental, terrigenous and igneous deposits. Marine sediments crop out in a few Italian areas (eastern Southern Alps, central-southern sectors of the peninsula and Sicily), as well as spread from the ex-Yugoslavia to the present Mediterranean sea, where they represent the westermost patterns of the old Tethys. In this context, data and interpretations vary sensibly from one region to another. Despite this, we have tried to establish the most typical events or features. Although the correlation and nature of some are still in doubt, the effort of reconstructing them is significant. Validity of some of our conclusions, however, stems mainly from their widespread importance.

1. INTRODUCTION The Permian of the areas examined (Fig.l) essentially consists of continental terrigenous and volcanic deposits. Intrusive bodies are also widespread (e.g., in Southern Alps, Pyrenees, Sardinian-Corsican block, Calabrian-Peloritan arc, and so on). Marine sediments, which represent the most westerly branches of the ancient Tethys, crop out in certain Italian sectors (eastern South Alpine region, central-southern places of the peninsula and Sicily), and in extensive ex-Yugoslav and Greek areas.

38

Fig. 1. Areas of southern Europe examined, in grey. (Abbreviation: ARC PEL-CAL="Calabro-Peloritan Arc")

This paper undertakes a comprehensive review, region by region, of well-known Permian stratigraphic sections in southern Europe, and presents palaeogeographic and other geological interpretations, with the aim of improving knowledge or the connection between the above continental and marine domains in a Mediterranean sector which was intensively involved in the Alpine deformations. However, the limited extent and notable variations of the Permian deposits preclude an exhaustive description here. In this context, the reader may examine other works of ours [e.g., 1-6]. Accordingly, we focus on a few selected areas, and give particular emphasis to the marine successions because of their major importance in comparisons and correlations. The western continental regions were described by G.Cassinis; F.Massari and C.Neri dealt with the eastern Southern Alps, and Neri also with the ex-Yugoslav and Hungarian territories; C.Venturini focused the Carnic Alps; G.Cassinis outlined the Permian of Romania and Bulgaria (partly with the collaboration of S. Yanev from the Bulgarian Academy of Sciences, Sofia), as well as of Greece; P. Di Stefano elucidated the marine conditions in the southern Apennines, Sicily, and Tunisia. The conclusions are a joint effort.

2. THE SOUTHWESTERN CONTINENTAL SECTOR

2.1. Spain During the Permian, the Iberian microplate was affected by tectonic movements which are related to the post-collisional stages of the Variscan orogeny. Intracontinental basins, filled by clastic sediments and volcanics, were formed. According to Virgili [2], marine sediments have yet to be identified, and correlation with marine deposits is very doubtful. Autunian and Thuringian macro- and microfloral assemblages are the most valuable chronostratigraphic tools. Generally, the former organisms correspond to an Early Permian age, while the latter generally indicate Late Permian. Some radiometric investigations also confirm Permian ages. From these data, and from an evaluation of the stratigraphic discontinuities, Virgili (op. cit.)

39

recognized two "Groups" within the Spanish Permian. The better known deposits crop out in the regions reported in Fig. 2. Permian strata are also present in the Balearic islands 9 The Lower Group, lying conformably or unconformably on the Stephanian or on older Palaeozoic rocks, reaches a maximum of more than 2000 m in thickness. It consists of fluvial and lacustrine varicoloured, fine- to coarse-grained detrital sediments, locally rich in andesitic and rhyolitic volcanic material of calc-alkaline type. However, in the Atlantic Pyrenean areas and in other parts of the chain, alkaline basalts crop out directly below the Buntsandstein. Autunian macro- and microfloras discovered in some places support an Early Permian age for the group in question; however, placing of the exact boundary with the Upper Group poses complex problems. The suggested dating remains a matter of debate, at least locally. In contrast with the deposits of the aforementioned early cycle, which accumulated within small basins generally controlled by strike-slip faults, the Upper Group is related to a marked extensional cycle, which ends diachronously throughout the Triassic 9Fluvial clastic redbeds, the Buntsandstein (200-600 m thick), spread over larger areas and covered the basins of the first cycle and the surrounding highs. Above the basal unconformity, the discovery of a Thuringian microflora (Lueckisporites virrkiae, Nuskoisporites dulhuntyi, Falcisporites schaubergeri, etc.), shows that Buntsandstein sedimentation began in some places, before the end of the Permian, as occurred in the Catalan Pyrenees, the Iberian Range and Majorca.

A Cantabdan Mts.

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Fig. 2. Upper Carboniferous, Permian and Triassic successions of selected areas of Spain, and their location in the inset map. Vertical distances not time- or thickness-related. ST: Stephanian macro- or microflora; AU AU: Autunian macro- or microflora; TH: Thuringian microflora; AN: Anisian microflora; AF: Anisian marine flora; A/L: Anisian/Ladinian microflora; L: Ladinian microflora. 1: marine limestone; 2: lacustrine dolomite; 3: mudstone, shale; 4: coal; 5: sandstone; 6: conglomerate; 7: volcanic rocks; 8: unconformity. From Virgili [2], slightly modified.

2.2. S o u t h e r n F r a n c e

South of the Central Massif, among a number of late Variscan continental basins, those of Lod~ve, Saint-Affrique and Rodez are the best known. The stratigraphic sections of Fig.3 may be informally subdivided into two groups [2].

40

In the Lod~ve basin, the Lower Group (about 800 m thick), resting unconformably on the Stephanian or on older rocks, generally consists of varicoloured fluviolacustrine and fluviopalustrine deposits (Fig.3). Ash layers mainly occur in the middle part.

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....

Fig. 3. Permian successions of southern France, and their location in the inset map. Vertical distances not time- or thicknessrelated. ST: Stephanian, AUi: lower Autunian, AUs: upper Autunian, SX: "Saxonian" Auct., TH: Thuringian, AN: Anisian. Radiometric data in Ma. Volcanic products are indicated by very thin dots (grey) and short dashes. The age interpretation of strata in the Lod6ve basin agrees with the hypothesis of Broutin et al. [7]

Macro- microfloras and vertebrate footprints point to Early Permian (Autunian); however, in the upper red-dominated sediments, Doubinger et al. [8] respectively ascribed two palynomorph assemblages to upper Lower Permian and to lowermost Upper Permian. Above an unconformity, alluvial-to-deltaic red conglomerates (Rabejac Fm.) grade laterally and upwards to playa sediments (Salagou Fm.). Both units form a new Permian cycle (locally over 2000 m thick) of still undefined age. According to Gand [9], this cycle includes a tetrapod ichnofauna assemblage, with Dromopus didactylus, HyloMichnus major, Antichnium salamandroMes, etc., which probably indicates an "early Saxonian" or Lower Permian age; however, as already stated, Doubinger's interpretation [8] agrees with a younger Late Permian (Thuringian) age. This bipartite stratigraphic subdivision is also recognizable in the Saint-Affrique basin. This basin shows lithological affinities with that of Lod6ve, and the palynomorph assemblages found in the lower cycle favour the hypothesis of correlation between the respective stratigraphic sections. In South Provence (Fig.3), the Permian System is widespread, and may reach more than 2000 m in thickness. In the Early Permian, some generally W-E grabens (Toulon, Cuers-Pont Solli+s, Luc, Bas-Argens, Estdrel), which are related to extensional movements, began opening on the border of horsts trending roughly N-S/W-E [ 10]. Locally (Estdrel), the green and red fluviolacustrine clastics of the underlying Avellan Fm. are interpreted as being due to a still earlier Permian (probably Autunian) sedimentary filling of a small, intermontane basin. Upwards, through an almost general unconformity located on the top of the Avellan Fm., there follow sequences (as much as 2000 m thick) of alluvial fan conglomerates and breccias, as well as fluvial sandstones and prevalently reddish and green mudstones, ascribed to

41 "Saxonian" and Thuringian. Alkaline volcanics, from acid (rhyolites, tuffs) to basic (basalts) composition, are locally intercalated in the form of flows, ignimbrites, dikes and pyroclastics. There is little evidence of Permian plutonism. Thuringian is dated by Ulmannia-rich macroflora, and by palynomorphs, with Lueckisporites virrkiae, Nuskoisporites dulhuntyi, and other forms; numerous tetrapod footprints have also been reported [2]. As in the Lod6ve and Saint-Affrique basins, the Triassic System begins with the Buntsandstein, unconformably overlying Permian or older rocks; the age of this unit is generally Anisian. 2.3. Ligurian Alps

In the Alpine chain, the Permian in the external Brian~onnais domain of western Liguria is mainly represented by calc-alkaline acidic ignimbrites and tufts, which have been affected by the Alpine metamorphism. Ending with sub-alkaline K-rhyolites, these products normally mark the most important Late Palaeozoic volcanic episode, ranging up to about 1000 m in thickness. These volcanics were deposited in grabens and semi-grabens, related to a (trans-) tensional tectonic context, and bounded by E-W/N-S faults. A Lower Permian age is suggested by stratigraphic position and general correlation. On the top, the Upper Permian Verrucano crops out unconformably. The Permian in the internal Brian~onnais domain of the Ligurian Alps is not substantially different from that of the external areas. Late Variscan intrusive rocks are also reported [11 ]. 2.4. Corsica - Sardinia

These islands primarily represent an area that was linked to stable Europe, especially to what are now Provence and Spain, as indicated by the general affinity of the late Palaeozoicearly Mesozoic geological scenario. Subsequently, they drifted and rotated counter-clockwise during the Miocene. After the Variscan collision, both these lands were affected by the intrusion and eruption of enormous volumes of igneous, intrusive and extrusive rocks. As in Provence, French geologists recognize a first magmatic cycle of calc-alkaline nature, mainly characterized by acidic products, which is connected with an orogenic period of subduction [ 12]. It generally extended from the Late Carboniferous to Early Permian (Autunian). In contrast, a second cycle of alkaline composition, from acid to basic, is related to an extensional regime of early rifting, probably ranging from late Early Permian (post-Autunian) to early Triassic times. Subsequently, fluviolacustrine clastics were mainly deposited in fault-bounded intramontane basins (e.g., in the Osani, Lu Caparoni, Seui, Perdasdefogu, Escalaplano areas), probably generated by transtensional tectonics. The Early Permian age of these troughs is locally welldocumented by rich Autunian floras [13]. A younger sedimentary cycle (or cycles), including Buntsandstein facies, probably developed in Late Permian-Middle Triassic (Anisian) times. The relative deposits have been identified only in a few, small places in Sardinia, such as Nurra and Gerrei [14], although they may perhaps extend to other parts of the island. As in Spain and France, this upper sedimentary, and locally also volcanic cycle was connected with a marked extensional regime. 2.5. Tuscany

Late Palaeozoic, mainly fluviolacustrine clastic deposits crop out in the Mts.Pisani and Iano areas [ 15, 16]. Autunian plant fossils occur in the S.Lorenzo black, silty shales of the former

42 locality. A Permian volcanism [1] would be indicated by the presence of rhyolitic rockfragments in the overlying Middle Triassic (?) Verrucano, as in the westem Apuane, Mts. Pisani, Larderello geothermal field; further indications of this volcanism are given by thin volcanoclastic products intercalated in the Iano Permo-Carboniferous sequence. Furthermore, in the middle part of Triassic Verrucano of the Monticiano area, the discovery of latest Carboniferous-early Permian fusulinid-bearing clasts is in keeping with marine conditions [17, 18]. Also, along the east coast of Elba, some Permo-Carboniferous dark grey clastic deposits yielding foraminifers referable to "Parafusulina sp." [19] suggest the presence of marine incursions, during the Early Permian (Artinskian) [20]. Southeast of Mount Amiata, in the Piancastagnaio geothermal field, fusulinids, microforaminifers and other organisms pertaining to Early Permian-Late Permian transition occur too [21 ]. Pasini [20] ascribed the whole association to the Cancellina Zone (Kubergandian). Along the Tuscan Maremma, mainly sandy, phyllitic rocks generally referred to the Carboniferous and/or Permian crop out beneath the Triassic Verrucano, in the Argentario promontory and in the nearby Romani Mts. [22]. 2.6. "Calabro-Peloritan Arc" This Alpine fragment, cross-cutting the Apenninic-Maghrebian chain, interrupts the western Tethyan sedimentary succession of Basilicata and reintroduces continental environments. Late Palaeozoic, mainly granitoid bodies occur extensively [23, 24]. Radiometric dating indicates Permian ages. A Permo-Carboniferous cover is unknown.

3. THE SOUTHEASTERN CONTINENTAL AND MARINE SECTOR 3.1. Southern Alps

3.1.1. Introduction Two major tectono-sedimentary cycles (megasequences), separated by a marked unconformity, can be recognized in the Permian-Early Triassic succession of the whole Southalpine area (Fig. 4). The lower cycle, which locally exceeds 2 km in thickness, consists in Lombardy and the Dolomites of acidic-intermediate volcanics and fluvial-lacustrine continental deposits (Collio and Tregiovo Fms., Ponteranica and Dosso dei Galli Conglomerates, Athesian Volcanics, etc.). In both areas, these deposits infill intramontane fault-bounded subsiding basins, which are surrounded by structural highs that essentially consist of Variscan metamorphics. To the east (Carnic Alps), the deposits of the first cycle are represented by a complex pile of continental-to-marine sediments of Late Carboniferous to Early Permian age (Pontebba Supergroup). Again, the deposits infill isolated basins. The upper cycle is more widely distributed and continuously overlies both the Lower Permian successions and the Variscan substratum. It consists of continental red beds (Verrucano Lombardo-Val Gardena Sandstone, Upper Permian), sulphate evaporites and shallow-water fossiliferous carbonates (Bellerophon Fm., Upper Permian),which are in turn overlain by mixed carbonate-terrigenous deposits of the Werfen Fm. (Lower Triassic). The second cycle includes the Induan, Olenekian and lower Anisian successions [4, 26], and is terminated by the onset of Mid-Triassic tectonics, which induced a significant reorganization of the paleogeography.

W Orobic Alps Val Camonica

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Fig. 4. Schematic non-palinspastic cross-section (trace on the inset map) through the Permian and the L o w e r Triassic o f the central and eastern Southern Alps. Datum line: restored top o f the Anisian succession, before the beginning of the Middle Triassic tectonics. From Italian IGCP 203 Group [25], modified, Massari and N e d [4, 26]

44

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Chronostratigraphic chart of t h e P e r m i a n s u c c e s s i o n in t h e W e s t e r n D o l o m i t e s

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Fig. 5. Chronostratigraphic chart of the Permian succession in the western Dolomites, and range of the main fossils recognized. Sequences of 3rd order identified in Upper Permian sediments are schematically indicated, without any stratigraphic symbol. Abbreviations: PCG, Ponte Gardena Conglomerate; CD, clastic deposits intercalating with volcanics. The V-shaped symbol corresponds to sulphate rocks; the grey area indicates shallow marine deposits, locally with oolitic beds.

45

3.1.2. Lower (1st) Cycle Lombardy and Western Dolomites. As previously stated, in the central-westem sector of the Southern Alps, the deposits of the lower cycle infill isolated continental basins. These basins were controlled by transtensional tectonics [27-30], and normally show SSW-NNE and W-E trends; moreover, they often coincide with long-lived tectonic lines (as the Val Trompia, Val Sugana, Giudicarie lines). In many places, the base of the succession is marked by polygenic conglomerates interbedded with sandstones and fine-grained clastics (Basal Conglomerate; Ponte Gardena Conglomerate; Figs. 4 and 5). The infill is dominated by continental (fluvio-lacustrine) clastics in the Orobic, Collio and other basins [31, 32], although volcanics (ignimbrites, tufts, etc.) of predominant rhyodacitic-rhyolitic composition may occur at various levels (Fig.4). In contrast, the Tione basin and the wide Trento-Bolzano basin are dominated by volcanic products, with minor, although very common, sedimentary intercalations (Figs. 4 and 5). The so-called "Athesian volcanics" of the Western Dolomites represent a very thick (up to 2000 m) succession of volcanic products characterised by a complex stratigraphic organization; the succession may be subdivided into two subgroups: a lower subgroup, which mainly consists of andesitic lavas, and an upper one, which is represented by rhyodacitic-to-rhyolitic ignimbrites [33]. The most prominent sedimentary body intercalated within the Athesian volcanics is the Tregiovo Fm. [3]. At its base, this unit consists of coarse clastics that grade upward into a thick monotonous sequence of grey to blackish lacustrine pelites. The Tregiovo Fm. is very important for its fossil flora, tetrapod footprints (Dromopus didactylus) and palynological assemblages, all of which suggest a late Kungurian to early Ufimian age [34, 35]. As the Tregiovo Fm. is overlain by the last volcanic products, its age may approximate to that of the end of the volcanic activity. Bio- and chronostratigraphy of all the above continental sedimentary deposits is mainly based on macroflora (Calamites sp., Sigillariae, Linopteris neuropteris, Walchia (? Lebachia) geinitzi, Sphenopteris suessi, Ulmannia spp., etc., in ascending order), palynomorphs (Potoniesporites sp., Distriatites insolitus, Corisaccites alutas, Crucisaccites varisulcatus, Lueckisporites wirkkiae, etc.), and tetrapod footprints (Dromopus lacertoides, D. didactylus, Amphisauropus spp., etc.) [36]. The available data suggest that the first cycle may have begun locally in the Late Carboniferous (Westphalian), but that it generally developed during the Early Permian (Artinskian-Kungurian), extending into the early Late Permian (Ufimian p.p. [34]; ? early Kazanian [35, 37] according to altemative interpretation of the palynofloras of Collio and Tregiovo Fms.). Radiometric investigation on a number of igneous bodies, both intrusive (Biella-Valsessera, Baveno, Bressanone, Cima d'Asta, etc.) and volcanic, generally converges on a Permian dating (276-268 Ma), which agrees substantially with the ages calculated for coeval and comagmatic plutonic bodies, such as Cima d'Asta granite (280-274 Ma). These ages correspond to the Artinskian-early Kungurian interval [38], or to Artinskian-Kazanian [39]. For a more detailed discussion on the relationships between radiometric and bio- chronostratigraphic ages, see Cassinis et al. [3]. Carnia. In the Camic Alps, the first Cycle is represented by more than 2 km of PermoCarboniferous sediments (Fig.6). The cycle unconformably rests on thrust and folded Variscan substratum that is made up of anchi- to non-metamorphic units. The unconformable succession, known as the Pontebba Supergroup (Nassfeld Schichten), was laid down within

46

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Fig. 6. The standard stradgraphic column of the Carboniferous-Permian succession of the Carnie Alps. It unconformably restson the thrustand folded Hcrcynian substratum and is subdivided into two major cycles.They correspond to the Lower and Upper Sequences, which are respectivelyPermo-Carboniferous and Permian in age.

47 discrete intermontane fault-bounded basins which rapidly opened to the sea towards the southeast [5]. Sediments accumulated in fluvial and deltaic environments, and grade upwards to shallow and open-platform conditions. Many macroflora- and fusulinid-bearing sites [4044] have been described in detail (Fig. 6). The lowermost unit is represented by discontinuous fan-delta coarse terrigenous sediments (Bombaso Fm.). They interfinger with shallow marine limestones and shales of the Auemig Group. The lowermost fossiliferous beds yield Fusulinid genera Eostaffella, Fusulina, Fusulinella and Quasifusulinoides, representative of the Myachkovian age (uppermost Moscovian) [45]. The Auernig Group has a maximum thickness of about 1100 m; the youngest beds are upper Gzhelian in age, and correspond to the Pseudofusulinoides Zone [46]. They are organized in cyclothems, with well expressed fourth-order eustatic cyclicity [47] that interferes with tectonic control [5]. The mainly shallow-marine carbonates and interfingered terrigenous sediments of the Rattendorf Group (450 m) follow without gaps or unconformities. The group was stratigraphically revised by Forke [48], who proposed for the Sakmarian-Artinskian interval of the Camic Alps a correlation between the fusulinid and conodont biostratigraphic scales, as well as a comparison with the Lower Permian sections of China, Japan, U.S.A. and Russia. The Asselian and Sakmarian ages are testified by Occidentoschwagerina alpina,

Pseudoschwagerina aequalis, Pseudoschwagerina confinii, Sphaeroschwagerina glomerosa, Robustoschwagerina geyeri and Zellia heritschi. The Trogkofel Group follows with a succession up to 400 m thick, exclusively consisting of carbonates. The lower beds are upper Sakmarian in age. The youngest beds are uppermost Artinskian (or very lowermost Bolorian) (Fig. 6), on the basis of fusulinid fauna, in which Pamirina darvasica, Minojapanella elongata and Nagatoella aff. orientis indicate the upper Pamirina and Pseudofusulina vulgaris Zone [44]. The beds roughly correlate with thick massive limestones identified by means of drillings in the north Adriatic Sea (Amanda, 1 bis well) [49]. The unit shows a rich fusulinid fauna, which includes Pseudofusulina,

Praeparafusulina, Acervoschwagerina stachei, Minojapanella wutuensis, Misellina claudiae and Misellina aliciae, and suggests an uppermost Early Permian age (Misellina Zone, more specifically Misellina claudiae Zone). In contrast, the Misellina Zone does not seem to occur in either outcrops of the Camic Alps and in the clasts of the Tarvisio Breccia (Upper Sequence), which reworks the Trogkofel Group carbonates.

3.1.3. Upper (2"a) Cycle Lithology and facies. The deposits of the upper cycle form a continous body that clearly extends from Lake Como, to the west, and, to the east, at least as far as Slovenia (Fig. 4); moreover, they also crop out in Hungary (Transdanubian Central Range, Bfikk), where they show a striking similarity in facies and in stratigraphy with the successions of the Southern Alps, as well as with those of certain ex-Yugoslav areas. Although this cycle also includes Triassic shallow marine deposits, the present paper only deals with the Permian part of the succession (Fig. 5); the Lower Triassic units are only taken into account in the discussion of the P/T boundary. The upper cycle unconformably lies on the Variscan substratum (metamorphic basement, non-metamorphic units of the Paleocarnic belt) or, occasionally, on the lower sequence (1 St cycle). A wide chronological hiatus, the extent of which will be discussed later, separates the 2 nd from the 1st cycles (Figs. 5 and 6).

48 In Lombardy and western Trentino, the Permian portion of the 2 nd cycle exclusively consists of continental (fluvial) red beds (Verrucano Lombardo, Val Gardena Sandstone), and reaches a thickness of 500-600 in the depocentral areas of Lombardy (Val Camonica) (Figs. 4 and 5). No direct biostratigraphic data are available for the Verrucano Lombardo, which is attributed to the Upper Permian on the basis of its stratigraphic setting (above the deposits of the 1st cycle and below the Lower Triassic Servino (-Werfen) Fm). In the whole area east of the Adige Valley (Dolomites, Cadore-Comelico, Carnia), the cycle also comprises lagoonal (evaporitic) and shallow marine sediments (Bellerophon Fm.); these sediments yield molluscs, brachiopods, calcareous algae and foraminifers that allow some correlation with the marine sequences of the Tethys (Figs. 5 and 6). The succession starts with continental clastics (Val Gardena Sandstone, 50-250 m thick); locally (especially in the eastern Dolomites and Carnia), the 2 nd Cycle starts with discontinuous coarse terrigenous sediments (Tarvisio Breccia and Sesto Conglomerate, 0-100m) (Fig. 6). They are interpreted as being linked to active fault scarps that favour the reworking of the substratum. Both in the Brenta-Adige high and in Carnia, syn-sedimentary tectonics caused the upper cycle to begin diachronously in different areas [50, 5, 4]; this tectonics controlled the paleogeography through most of Upper Permian, and occasionally during Lower Triassic. The facies associations identified in the Val Gardena Sandstones suggest a fluvial regime subject to rapid and erratic fluctuations in discharge. The fluvial system is characterized by progressive downstream decrease in channel dimensions and in average discharge, and by final transition into a network of terminal-fan distributaries merging into coastal sabkha mudfiats. Palaeosols are represented by vertic and calcic soils, and suggest a warm-to-hot, semiarid climate with strongly seasonal rainfall distribution. The overlying Bellerophon Fm. (0-350 m) essentially consists of two units: a lower sulphate evaporite-bearing unit, with cyclically alternating dolostones, marls and laminated gypsum, and an upper shallow-marine carbonate unit, characterized by grey-to-blackish peloidal bioclastic wackestone and packstone rich in benthic foraminifers, calcareous algae and molluscs (Figs. 5 and 6). In the north Adriatic Sea, the drilled Amanda Fm. [49] consists of a lower lithozone in the form of a 60 m thick unfossiliferous limestone breccia (Tarvisio Breccia), that unconformably overlies the Goggau Limestone (Misellina Zone); the Amanda Fm. is in turn paraconformably (?) overlain by limestones, shales, marls and sandstones. Fusulinids are rare, but palynomorphs abundant. According to Sartorio and Rozza, this succession seems to be correlatable with the upper cycle of the Carnic Alps, on the basis of Khalerina pachiteca, which presumably corresponds to the Neoschwagerina Zone. The age attributed to the Amanda Fm. obviously and significantly affects the evaluation of the gap between the two main cycles.

Sequence stratigraphy. At least ten Ill-order sequences have been identified and tentatively correlated within the whole 2 nd [4, 26]; five of these, and the lowest part of the sixth one, pertain to the Upper Permian succession (Fig. 5). As a whole, the 2nd cycle is characterized by a trangressive trend that reaches its acme during the Spathian, and is followed by generalized regression during lower Anisian. Among the five Ill-order sequences recognized within Val Gardena Sandstone and Bellerophon Fm. from Western Dolomites to Carnic Alps, the two lowest sequences are mainly represented by continental red beds. Only in Carnia (Paularo section, 1st sequence)

49 and in the Bletterbach section of the western Dolomites (2 nd sequence) do minor marine deposits occur. The 3 rd sequence shows complex facies interfingering and pronounced lateral transitions; the sequence is fluvial-dominated in the westernmost area, and grades eastward (seaward) firstly to terminal-fan and coastal sabkha facies associations, and subsequently to a subtidal evaporite complex that pertains to the Bellerophon Fm. The latter is characterized by cyclic alternations of dolostone and laminated, gypsum, which are thought to reflect alternation between under- and hypersaturation in calcium sulphate; both the latter conditions are determined by small climatic/eustatic changes. The evaporite unit was laid down in a tectonically barred basin that is characterized by differential subsidence, which extends from the Western Dolomites [51] to the Carnic Alps [4]. To the east, the unit is bounded by carbonate shoals localized on structural highs of the Carnic area. The upper two sequences (4th and 5th) are characterized by a more uniform subsidence rate, which in turn leads to significant changes in palaeogeography: a low-gradient homoclinal ramp replaces the previous barred basin. The successions are dominated by shallow-marine fossiliferous limestones with marly interbeds. The westermost sector of the Dolomites is dominated by marginal-marine facies associations (characterized by marly-silty dolostones with rare gypsum); further westwards (Adige Valley), the associations grade into thin packages of continental red beds.

Permian -Triassic boundary. The P/T boundary does not represent a sequence boundary [4]; the boundary between sequences 5 and 6 lies at the base of a thin unit (0.5-2 m) consisting of highly diversified bioclastic packstone microbiofacies (Globivalvulina, Paraglobivalvulina, Nanldnella, Reichelina, etc.) [52] and containing macrofaunas dominated by the brachiopods Comelicania, Ombonia, etc. ("Comelicania beds") [53, 54], (Fig. 7). This unit represents the very top of Bellerophon Fm., and may be attributed to latest Permian. It is overlain by the Lower Triassic oolitic Tesero Member. However, although this unit contains the first Triassic fossils (e.g., Bellerophon vaceki, Towapteria scythica) from its base upwards [53], it still yields Permian fossil assemblages ("mixed-fauna") [55], at least as far as 2-3 m above its base. Both the Comelicania beds and the Tesero Mb. consist of backstepping parasequences that pertain to the transgressive systems tract of the 6 th Ill-order sequence. The base of the Tesero records: a) a considerable westward shift in the coastline, from Adige Valley to central Lombardy; b) an abrupt increase in the average hydrodynamic energy of the environment. This event is widespread and coeval in western Tethys, and is probably related to a major oceanographic change. Age of Upper Permian deposits. Age data conceming the Upper Permian deposits of the Dolomites and Carnia are based on palynostratigraphy, tetrapod footprints, foraminifers, molluscs and brachiopods (Figs. 5, 6 and 7); further data are provided by magnetostratigraphy and stable isotope stratigraphy [3]. Tetrapod footprints. The ichnofossils of the Val Gardena Sandstone have been studied, especially in the Bletterbach section, by a number of authors [56, 57, 35, etc.]; they identified a single association that lacks evidence of vertical evolution and is characterized by the ichnogenera Pachypes, Rhyncosauroides, Dicynodontipus and Chirotherium. The above authors stressed the very "late" character of this Permian ichnofauna, whose first occurrence is very close to the base of Val Gardena Sandstone in the Bletterbach section.

50

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Fig. 7. Ideal stratigraphic section of the succession at the P/T boundary in the Dolomites, mainly based on the real Tesero and Sass de Putia sections, as well as on other unpublished sections. Key: 1, oolitic grainstone; 2, intraclastic grainstone and packstone; 3, packstone with foraminifers and algae; 4, bioclastic packstone with bivalves, ostracods and microgastropods; 5, mudstone and wackestone; 6, marly mudstone; 7, dolostone; 8, marly dolostone; 9, marl; 10, mud-cracks; 11, fenestrae; 12, bioturbation; (a) third order stratigraphic sequences according to Massari et al. [4]; (b) parasequences at the base of sequence 6. Source of paleontological data: - Comelicania, Janiceps and Ombonia p.p.: Sass de Putia section, [52-54]; - echinoderms, brachiopods and molluscs of the Tesero Member: Tesero section [55, 25, 52, 53]; - foraminifers and algae: Tesero and Sass de Putia sections, see above quoted references; numbers on the right of the bars indicate the average number of genera; - conodonts: Bulla section, [61] simplified

Palynology. Palynological data also support the hypothesis that the Val Gardena SandstoneBellerophon Fm. is Late Permian in age. According to [4], the microfloral association is characterized by the following events: a) the first appearance of Endosporites ("Playfordiaspora") hexareticulatus (recorded in the Bletterbach section about 60 m above the base of Val Gardena Sandstone, within the 2 nd depositional sequence (Fig. 5); b) the subsequent appearance of Lueckisporites parvus, in the upper part of the 3 rd depositional sequence, which corresponds in most sections of the Dolomites and Camia to the lowermiddle Bellerophon Fm. The onset of the Val Gardena red beds possibly took place in postKazanian times [4]. Marine fossils. The microfossils (foraminifers and algae) and macrofossils (bivalves, gastropods and cephalopods) occurring throughout the Bellerophon Fm. may be correlated to the Upper Permian faunas of the Tethys Realm, but their general facies-dependence, and frequent lack of main index-species, preclude a reliable biostratigraphic subdivision [52]. The

51 tentative attribution of the Bellerophon Fm. to the Dzhulfian-Dorashamian interval is confirmed by the finding in the Reppwand section of the world-wide Late Permian large positive anomaly of marine carbon isotopes (dl3C) [58]. Only, the brachiopod associations occurring close to the P/T boundary (Fig. 7), within a very limited vertical interval, have high bio- and possibly chrono-stratigraphic potential [52, 54]. The Comelicania, Janiceps, ?Araxathyris and Ombonia association, which marks the uppermost layers of the Bellerophon Fm., has been attributed to the uppermost Dorashamian [53]. The recent finding of a specimen of Paratirolites sp. from a level located a few metres below the "Comelicania beds" (M.Seceda, Ortisei) (Posenato, pers. comm.) strongly supports this attribution. The ?Crurithiris extima, ?Schuchertella, ?Spinomarginifera etc. assemblage occurring in the Tesero Mb., associated with Permian microfossils and Induan molluscs, has been dated to the lowermost Triassic by analogy with the mixed faunas of the Salt Range [59,

60]. Conodonts are usually very rare in Bellerophon Fm.; the high time-consuming sample disaggregation and hence the high cost of research on conodonts, means that studies are almost exclusively limited to the intervals containing P/T boundary. The vertical range of conodonts was studied in the Tesero Mb. of Bulla section (Ortisei), where the uppermost Bellerophon Fm. is unfortunately barren in conodonts [61 ]; however, Hindeodus latidentatus has been found 30 cm above the Bellerophon/Werfen boundary, and H. parvus, which is regarded as a marker of the base of the Early Triassic, occurs 130 cm above the boundary. Some caution may be required in the interpretation of these data, not least because they were obtained from a single section. Furthermore, lithologies of the Tesero Member (oolitic grainstone, bioclastic grainstone and packstone) are not very favourable to conodont preservation, and thus the first occurrence of taxa probably does not represent real FAD. Data on the carbon isotopes in the Tesero section were obtained [62]; speculative extension of these data to the Bulla section would suggest that the first occurrence of H. parvus is about 1 m above the main shift in 13C. The authors of the present paper believe that the base of the Tesero Mb., which is characterized by an abrupt decrease in Permian taxa, by ~3C shift and by the first occurrence of Triassic taxa, can adequately represent the P/T boundary in the Southern Alps. Magnetostratigraohy. In the Paularo section, that is the standard reference for the Val Gardena Sandstone of the Carnic Alps, the Illawarra reversal event has been displayed [63]. It is placed at about 170 m above the transition with the Sesto Conglomerate, and falls within the 2 nd III-order depositional sequence of Massari et al. [4]. As a consequence, and in absence of useful paleontological evidence, the maximum basal age of the upper cycle is tentatively placed near to the Kazanian-Tatarian boundary (Figs. 5 and 6) of Menning's chronostratigraphic scale [39]. The gap between the lower and upper cycles may thus pertain exclusively to Kazanian (perhaps only by a part of Kazanian).

3.2. Ex-Yugoslavia In general, the mainly marine Upper Palaeozoic succession in ex-Yugoslavia is so scarcely documented that reliable reconstruction is currently not feasible. Connections with the Carnic Alps have been recognized in the northern Julian Alps, southern Karawanke, central Slovenia and coastal area of Croatia (Gorski Kotar and Velebit Mts.). However, the first area is locally characterized by Upper Permian limestones with SE Asian fusulinids (Neoschwagerina, Sumatrina, Veerbekina) of Murgabian age, whereas in the second area such limestones are

52 lacking, and are probably replaced by Val Gardena Sandstone [64]; in central Slovenia, a polymict unit (Ljubljana Beds), locally bearing Middle Carboniferous and older rock fragments, is interpreted as having developed from the late Carboniferous to early Permian ages; Val Gardena Sandstone follows upwards. The latter is marked by a volcanic event of basic composition, and is overlain by the shallow-marine Zazar beds; Paleofusulina appears at the beginning, followed, slightly above, by a Caucasian/Indo-Armenian brachiopod fauna

(Tyloplecta yangtzeensis, T. richthofeni, Tschernyschewia typica spinomarginifera, Linopiroductus lineatus, Comelicaniae, etc.). In Gorski Kotar, near Rijeka, interesting data are given by local events that resemble those of the Sicilian "Sosio" (Guadalupian s.1.); likewise the presence is remarkable of the clastic Trogkofel, which seems to continue southwards (Kosna beds?) and towards Bosnia. In the Velebit Mts., the most evident differences from the Camic Alps sequence mainly regard the Middle and Upper Permian, both ages being represented by carbonates and faunas that have also been noted in Serbia (Jadar). In northeast Croatia and in Bosnia, the available data do not permit clear interpretation and comparison of the Permian System. Our data for the Upper Paleozoic of Montenegro suggest varying scenarios. Analogies with Basilicata and the Julian Alps are given by the appearance of Triassic conglomerates, which clasts of Middle-Upper Permian carbonate rocks. Evidence of a brachiopod fauna, with Comelicaniae, etc., connects this area to the Dolomites and central Slovenia, and is hence worthy of note. In Serbia, further variations have been identified. In the westem part, a presumed Upper Permian-Triassic sequence, which consists of continental detrital sediments, rests unconformably (with a large gap) on Carboniferous clastic deposits. The Permian of eastem Serbia, in the Jadar region, is affected by lateral variations that generally occur in shallowwater environments. Units equivalent to the Val Gardena Sandstone and Bellerophon Fm., the latter with aspects partly differing from those of Slovenia due to the absence of Comelicaniae and Paleofusulina, again lie unconformably on presumed Permo-Carboniferous beds.

3.3. Hungary Our account of the Permian successions of Hungary will necessarily be brief, and will focus on the Upper Permian sequence of the Transdanubian Central Range, which is very similar to the Val Gardena Sandstone-Bellerophon Fm. of the eastern Southalpine area [65]. The major areas for the Permian-Triassic succession in Hungary are the following. a) The Mecsek Mountains (pertaining to the Tisza unit, south of the Central-Hungarian megashear zone): Permian and Triassic are of Germanic type, represented by fluvial red beds (up to Middle Triassic, when lagoonal to shallow-marine deposits occur). According to a sketch of the stratigraphic relationships [66], it seems that this area too has two major sedimentary cycles; the lower one (Upper Carboniferous-Lower Permian) is deposited in isolated basins and is associated with acidic volcanics,while the upper one (uppermost Permian-Lower Triassic) is more widely ("blanket like") distributed. b) The Transdanubian Central Range. It is a very well documented area, thanks to the numerous stratigraphic wells that cross the Permian and Triassic successions, and to the scattered outcrops. A thick (up to 1 km) Upper Permian succession, which is correlatable with the upper cycle of the Southern Alps, overlies a phyllitic basement that is locally intruded by Lower Permian acidic bodies (Rb/Sr ages ranging between 262 and 270 Ma) [65]. The above quoted succession consists of: fluvial red beds (Balaton Red Sandstone), corresponding to the Val Gardena Sandstone; sulphate evaporites which cyclically alternate with dolostone and

53 marl (Tabajd Evaporite), and which are partly correlatable to the evaporitic unit of the Bellerophon Fm.; carbonate rocks, mainly dolomitized, with marly-silty interlayers (Dinny6s Dolomite), partly correlatable to carbonate units of the Bellerophon Fm. The uppermost Dinnye6s Dolomite, is partly represented by limestone layers displaying microbiofacies that are in turn characterized by the foraminifers Paraglobivalvulina, Pachyphloia, Nankinella, Staffella, etc., and by the algae Atractyliopsis, Mizzia, Gymnocodium, etc. While to the SW the succession is only marked by red beds, to the NE it consists of a complex alternation of red beds, evaporite and carbonate; this alternation enables the recognition of a number of IIIorder depositional sequences. According to Neri, who observed stratigraphic boreholes from Transdanubia, it is possible to recognize in the Hungarian succession at least the boundary between sequences 3 and 4 of Massari et al. [4], which more or less corresponds to the boundary between sequences B and C of Majoros [65]. Similarly, the P/T boundary and the Lower Triassic succession demonstrate sedimentary and paleobiological events that are easily correlatable with those of the Southern Alps [66, 67]. Here too, the base of the Induan sequence is represented by oolitic grainstone with survivor Permian fossils, followed upwards by marl, silstone and carbonate, with typical Triassic fauna (e.g., Claraia gr. wangi). To enforce the correlation, brachiopods of genus Comelicania locally occur a few tens of centimetres below the first oolitic layer (well Gardony l-B, Neri, unpublished data). The oolitic horizon, which is correlatable to Tesero Member of the Dolomite Alps, has been inserted in varying lithostratigraphic units, on the basis of paleogeography (from NE to SW, the Alcsutdoboz Limestone, the Aracs Marl and the N~idagskrtit Dolomite) [67], but in any case it marks the base of the Triassic System. c) The B/ikk Mountains. The Upper Permian succession shows a more marine character, as its upper part is dominated by a thick (200 m) limestone unit (Nagyvisny6 Fm.), with abundant macrofauna (Waagenophyllum, brachiopods, nautiloids) and the classical Upper Permian microbiofacies. The literature proposes a correlation between this unit and Upper Permian deposits in Slovenia (Zazar Limestone), Serbia, etc. [68]. The Nagyvisny6 Fm. represents the upper part of a transgressive succession that unconformably overlies upper Carboniferous conglomerates, and starts with Val Gardena-like clastics, followed upwards by marl and dolostone. It is overlain by Lower Triassic Gerennav~ir Lms., which are constituted at the base by thin-bedded micrites with marly interlayers, resembling the base of the Werfen Fm. in the Cadore-Carnia area. A thin (8 cm) marl layer exactly on the formational boundary yielded a remarkable mixed fauna with Permian and Triassic elements. 13.4. Romania

Our scarce knowledge of the Permian deposits in this country prevents us from describing and interpreting them in a wider geological context. They occur in the Apuseni Mts., South Carpathians (Banat region), Moesian platform and North Dobrudgea. The Apuseni succession of the Ariesh valley (Fig. 8) consists of continental red clastics and volcanics, which are generally related to the Lower Permian [69] and unconformably overlie the crystalline basement. Lower Triassic Buntsandstein crops out above, followed in turn by finer-grained dominant redbeds and Middle Triassic carbonate platform deposits. In the Southwestern part of Romania (Banat Mts. area; Fig. 8), the Permian Ciudanovita Fm. of the Resita basin (Getic Nappe) is represented both by lacustrine black argillaceous shales (150-300 m thick), with abundant Autunian plants (Autunia conferta, Walchia piniformis, Ernestiodendron filiciformis, etc.), grading laterally and upwards into dominant fluvial red clastics (up to more 1 km), locally intercalated by pyroclastic and rhyolitic rocks. This latter unit, which locally

54

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steps down onto the crystalline basement, also displays macro- and microflora remnants (Walchia piniformis, Ernestiodendron filiciformis, etc., Potoniesporites novicus, Granulatisporites sp., Crucisaccites sp.) [70], again related to the Autunian, i.e. to the Lower Permian. Near Anina (Ponor quarry), mainly Lower Liassic clastic deposits, which are rich in fossil plants [71, 72], and which resemble the Austrian Gresten facies, are superimposed onto a continental red clastic unit; this latter generally differs from the upper part of the already mentioned Ciudanovita Fm., and could be ascribed to the Upper Permian. As a consequence, the Triassic deposits appear to be missing in this area. Further to the South, on the westem side of the river Danube, acid volcaniclastic products (500 m), overlain by continental redbeds (up to 300 m), occur along the Jeliseva valley 9On the basis of flora remnants (Lebachia piniformis, Hymenophyllites semiallatus, etc.) and of correlation, these deposits have been generally assigned to the Lower Permian. Locally, however, some clastic redbeds of as yet undefined age unconformably overlie a gabbroperidotitic Proterozoic basement. Like the Resita basin, the Permian succession of the investigated region is directly superimposed by the Lower Liassic deposits in Gresten-type facies. According to Yanev (pers. comm.), the Permian continental rocks, which have been investigated only by means of drillings in the Moesia platform, generally show close affinities with those of the Bulgarian portion. In the north-central sectors of this Romanian block (between Teleorman and Jiu rivers), basic, as well as acid, effusive magmatites also occur [70]. In North Dobrudgea, the Macin Zone Unit includes in the Crapcea Hill, west of Balabancea, an Upper Palaeozoic continental succession (known as Carapelit Fm., maximum about 1700 m thick), which directly overlies Variscan metamorphic rocks. The sequence consists, from

55 base to top, of grey and red massive fanglomerates, calcalkaline rhyolitic volcaniclastic products (> 50 m), green and red silty-shaly and sandy flood-plain deposits (150 m), locally interrupted by conglomeratic intercalations; in addition, grey-dark, laminated, presumably lacustrine deposits crop out [74]. On the basis of correlative data, the age of this succession could be generally ascribed to a Late Carboniferous-Early Permian interval. In contrast the Carapelit Fm. from the Camena area, which displays polymictic breccias, varicoloured sandstones, siltstones and shales, and yields an Early Triassic palynoflora (Antonescu, unpubl, data), should be assigned to this interval [75]. As a consequence, the temporal distribution of the Carapelit Fm. are still a matter of debate. In the Tulcea Unit, the sedimentary cover outcropping in the Monument Hill of Tulcea starts with clast-supported, red compact alluvial conglomerates, about 50 m thick, which unconformably rest on a Devonian crystalline basement locally intruded by an alkaline porphyritic dike. This clastic unit, including metamorphic and subordinate volcanic rocks, shows a great affinity with some Verrucano facies of the Italian Southern Alps. These terrigenous deposits, interpreted to be of Early Triassic age, grade upwards into: 1) greenish-grey argillaceous siltstones and sandstones, which yield a fairly rich Eumorphotis - bearing bivalve fauna that suggests a late Griesbachian age, and 2) a thick sequence of thin-bedded blackish marly limestones and marly shales, which yield a Spathian Tirolites cassianus - bearing ammonoid fauna [75]. Thus, in the light of the above data, the Upper Permian deposits of North Dobrudgea require further research.

3.5. Bulgaria The Permian of Bulgaria is generally made up of continental clastic sediments and of acidicto-intermediate volcanics [76]. From north to south, three domains are recognizable. In the Moesia platform (Fig. 9), where the succession has been investigated only by means of drillings, the folded Palaeozoic basement is unconformably overlain by Rotliegend-type clastic beds, which have been related to Early Permian. Calc-alkaline volcanics occur locally (Targovishte, Kaliakra and other places). This succession is unconformably overlain by breccias, conglomerates and sandstones with reworked volcanogenic deposits. As it moves upwards, the sequence tends to reveal breccias, conglomerates and sandstones, with reworked volcanogenic deposits, again through an unconformity. The subsequent massive red clastics, still lying unconformably on the above-mentioned Permian, or older rocks, can be grouped into a new extensive cycle. Eastwards (Provadiya synclinal), these clastic deposits pass laterally to evaporitic-carbonate bodies, which have been ascribed to Late Permian on the basis of palynological data (Lueckisporites wirkkiae, Klausipollenites shaubergeri, etc.) and regional correlation [78]. On the top there are silty-shaly and sandy, well-sorted, and distinctly stratified clastic deposits. The Lower Triassic Buntsandstein generally occurs in higher position, above a marked and widespread unconformity. Throughout the Balkan Mts. (Fig.9), Permian deposits infill isolated intermontane faultbounded subsiding basins. Generally they begin with Rotliegend-type alluvial-to-lacustrine and plant-bearing sediments, which may be locally ascribed to Stephanian-Permian. Coal layers also occur. In some places, however, the Permian deposits rest directly on a folded Variscan basement. Calc-alkaline, generally acidic volcanics, along with subvolcanics and deeper igneous bodies, also crop out locally (Sliven, Berkovica, Levski peak and in preBalkan areas). On the Stephanian-Permian transitional-unit (Fig. 9), there are coarse to finegrained, polygenic red sediments, as is the case in the Belogradcik area and elsewhere. New fluvial, perhaps deltaic, red sandstones and conglomerates lie unconformably above. Again

56

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through a marked angular unconformity (up to 90 ~ locally), the already mentioned Upper Permian red sandy unit of the Moesian platform, lacking in volcanics, follows upwards. Triassic Buntsandstein occurs unconformably at the top. In the Kraishte region, i.e. in southwestern Bulgaria, there are locally some uppermost Carboniferous ?-Lower Permian clastic sediments. In contrast, the Upper Permian red cycle of the other country sectors shows wider development. In southeastern Bulgaria, Permian rocks are notably rare, only occurring in two places, exactly in Strandzha and in the eastern part of the Rodope massif, where they consist of shallow-marine carbonate sediments. These outcrops are attested by the discovery of some algae (Mizzia velebitiana, Epimastopora piae, etc.) in the former region (Kondolovo), and of foraminifers (Agathammina pusilla, Neoendothyra parva, Colaniella, etc.), which occur within silicified carbonate rock-fragments reworked into an Upper Jurassic-Lower Cretaceous terrigenous olistostrome, in the latter region (near Dolno Lukovo). However, the outcrops in question are generally interpreted as a result of tectonic transport from southern sectors, and specifically the Strandzha deposits still promote dating controversy.

4. T H E S O U T H E R N M O S T

MARINE SECTOR

4.1 B a s i l i c a t a

In the Southern Apennines, Fusulina limestones occur as reworked pebbles within the Lower-Middle Triassic Monte Facito Formation of the Lagonegro basin [79]. The fusulinids

57 in these clastics belong to the Neoschwagerina craticulifera and Neoschwagerina margaritae subzones respectively of the Middle and Upper Murgabian [80]. Elements lacking fusulinids, but showing small foraminifera of the Midian-Dorashamian ages, have also been recognized [81 ]. The fusulinid and foraminifer associations are similar to those of the Sosio succession in Sicily [82]. These reworked Permian limestones are considered to be possible remnants of the Northern margin of the Permian basin in Sicily.

4.2 Sicily Along the Maghrebian chain, Permian deposits consisting of mostly deep-water siliciclastic and clastic-carbonate rocks, have been identified in the Lercara-Roccapalumba area and in the Sosio Valley of central-western Sicily (Fig. 10- A). The age of these deposits spans from the late Artinskian up to latest Permian. They occur as "broken formations" in strongly deformed allochthonous complexes, which also show tectonic slices of Fusulina limestones, first described by Gemmellaro [83], and of Triassic deep-water rocks. These Permian-Triassic unit, known as Lercara Formation [84], are considered to be remnants of a basin fill in a wide deep-water domain (Sicanian basin) that extended along the Gondwanian margin (Fig. 10 C). As a consequence of the Neogene accretion of the Maghrebian chain, the Permian-Triassic rocks were sheared off either from their substrate or from the overlying sedimentary successions. This shearing initiated the floor thrust complexes that lie at the base of major basin-derived thrusts of Mesocenozoic rocks (Sicanian units). The Sicanian thrust pile is in turn overthrust on more external Mesocenozoic platform units that are southward connected to the foreland areas of the Hyblean plateau and the Pelagian Block (Fig.10 A). The Neogene thrusting obscured stratigraphic relations, so that only a composite stratigraphic column of the Permian succession can be restored (Fig. 10 B). The column is based on a large dataset collected in the last decade from the Lercara and Sosio allochthonous complexes [85, 82, 6]. The oldest unit is exposed in the Lercara area, and consists of a thick package of siliciclastic turbidites, known as Kungurian flysch [85]. They are characterized by reddish and greenish shales, siltstones and sandstones displaying Bouma divisions, flute casts and Nereites ichnofacies. Metamorphic and volcanogenic grains in the sandstones, along with abundant quartz and micas, suggest siliciclastics in the Kabilo-Calabride domain as the origin of these turbidites. Conodonts from the pelitic interbeds support the hypothesis that these rocks are late Artinskian-Kungurian in age [85]. Calcareous turbidites and debrites are also occasionally interbedded. Microfacies analyses suggest derivation from the disruption of an early Permian carbonate platform [86]. The finergrained beds are skeletal-lithoclastic grainstones/packstones with fusulinids, Tubiphytes sp., Archaeolithoporella sp., calcareous algae (Mizzia sp., Epimastopora sp., Pseudovermiporella sp.) and sponge fragments. The debrite beds consist of clast-supported, angular pebbles and of boulders of sponge/Tubiphytes boundstones, Tubiphytes/Archaeolithoporella bindstones, phylloid algae boundstones, Mizzia - fusulinid grainstones-packstones, and crinoidal packstones. On the basis of algal assemblages and fusulinids as Pseudofusulina (Leeina) kraffti Schellwien and P. vulgaris Schellwien [82], these elements are probably Lower Permian in age. Diabasic intrusions in the Kungurian flysch are common [87]. Radiometric dating for these magmatic rocks, which have a tholeitic affinity, is not available. However, structural and

58

Fig. 10 - A) Mediterranean area, and index map of the Permian outcrops from the southern Apennines, Sicily and Tunisia. B) Composite columnar section of the Permian deep-water succession from Sicily, restored from the allochthonous Permotriassic complexes from the Lercara area and the Sosio Valley. C) Paleogeographic sketch showing the western termination of the Permian Tethys [85, modified]. Tu siliciclastic/carbonate platform deposits in Tunisia, transitional to deeper-water shales. SI = deep-water siliciclastic and elastic-carbonate deposits in Sicily (Sicanian basin). LA -- shallow-water Middle and Upper Permian Fusulina limestones of the Lagonegro domain in Southern Apennines and possible prolongation in the Imerese domain in Sicily (IM).

59 textural characters recently observed along their contact with the turbidites suggest an intrusion in soft sediments, and thus an Early Permian age [88]. Younger Permian rock packages are exposed in the Sosio complex, outcropping along the Torrente San Calogero near Palazzo Adriano. This complex consists of tectonic slices of Middle and Upper Permian siliciclastic rocks, Fusulina-bearing limestones, Wordian ammonitic limestones, but also middle and Upper Triassic radiolarites, nodular limestones and Halobia limestones and marls [85]. The oldest Permian unit recognized in this area is represented by siliciclastic turbidites, named San Calogero flysch [6]. It consists of grey-to-blackish pyritic shales and siltstones, with intercalations of micaceous sandstones and hybrid arenites. Owing to the thrust tectonics, it outcrops as a chaotic clayey mass containing sandstone blocks. On the basis of conodonts, the age of this unit is lowermost Middle Permian [89]. Scattered elements of dark grey calcilutites with circumpacific radiolarians of early Kungurian age, and of shallowmarine limestones, suggest that these deposits could have been affected by synsedimentary sliding and reworking (Olistostrome unit) [85]. Stratigraphically younger deposits are found in a small limestone block known as Rupe del Passo di Burgio. They consist of white ammonoid-bearing calcilutites and reworked skeletal calcarenites that are interpreted as hemipelagic carbonates deposited in a distal slope setting. The hypothesis that these deposits, named Rupe del Passo di Burgio limestones, are Wordian in age is supported by rich fossil association, which is characterized by fusulinids, ammonoids, ostracods, crinoid ossicles, holoturian sclerites and conodonts [83, 90, 85, 91]. Varying Wordian deposits, consisting of yellow-to-grey clays with Mesogondolella siciliensis (Kozur), are found in a small outcrop close to the Rupe del Passo di Burgio [85]. Upper Permian limestones are exposed in the Pietra di Salomone, the most famous and fossil-rich limestone block in the Sosio Valley (about 200 m long and 100 m wide), but also in two smaller blocks, known as Pietra dei Saracini and Rupe di San Calogero. Since Gemmellaro's careful descriptions [83], many paleontological studies have been carried out on these deposits, which were regarded as reef limestones. Recent sedimentological and stratigraphic contributions [82] indicate that the Pietra di Salomone limestones are composed of poorly defined beds of coarse calcareous breccias that grade upward to fine-grained calcareous turbidites. The breccia elements consist of platformslope derived carbonates that span in age from Artinskian to Djulfian. Reef-derived boundstones/rudstones prevail, but floatstones and grainstones are also commonly observed. Sponges, Tubiphytes, Archaeolithoporella, phylloid algae, richthofenid brachiopods are the main framebuilding organisms, and are associated with highly-diverse, fusulinid- comprising assemblages. The Neoschwagerina, Yabeina and Reichelina Zones are represented [82]. The presence of rare conodonts of Late Permian age (H. Kozur, pers. comm.) and of Reichelina sp. in the matrix, suggest that the Pietra di Salomone limestone is Late Permian in age. These limestones, which reach a thickness of about 70 m, consist of debris flow and turbidite sediments deposited in a base-of-slope position. They were probably interlayered with the youngest Permian deposits yet to be recognized in the Sosio complex, which consists of Late Permian red clay and turbidites. The red clays of this last unit contain abundant circumpacific radiolarians, paleopsychrospheric ostracods and conodonts of Late Permian (Djulfian to Changxingian) ages [85, 92, 93]. Fine-grained siliciclastic and carbonate turbidites are commonly interbedded to the red clays. The calcareous turbidites are mostly skeletal

60 grainstones/packstones, with abundant Reichelina simplex Sheng, Archaeolithoporella/ Tubiphytes fragments and conodonts. On the basis of the stated lithostratigraphic units, the restored Permian succession from Sicily (Fig. 10 B), indicates a sediment-gravity filling of a deep-water basin, and that the infill persisted throughout the latest Artinskian up to the latest Permian. Siliciclastic turbidites were supplied by the Kabilo-Calabride Hercynian domain, while the abundant intra- and extrabasinal shallow-marine carbonate-clastics were repeatedly transported from adjacent carbonate shelves. The deep-water sedimentation in this basin persisted throughout the Mesozoic. 4.3. Tunisia Permian deposits are well documented in the Jeffara basin [94], a strongly subsiding basin that is related to a wide rift zone, which in turn extends as far as the North Syria [95]. Up to 6 km thick, the basin contains Middle and Upper Permian terrigenous-carbonate platform successions that were deposited with an upward regressive trend [96]. On the basis of wells and outcrop sections in the Tebaga area, and of wells in the Bir Soltane and Djeffara areas, facies distribution shows that the Permian platform deposits grade northwards into deeperwater shales and a reef belt [97]. These deposits cover unconformably either occasionally preserved Lower Permian shallow-water limestones, shales and sandstones, or older rocks. This unconformity indicates a mid-Permian uplift and erosion in the Jeffara basin. The Permian of Tunisia is considered to be the southern margin of the deep-water basin along the Gondwanian margin [85].

4.4. Greece In this country, Permian is represented by sparse and small exposures of generally marine deposits. Occurrences of Permian rocks have been recognized both in continental and insular areas. However, because the strong Alpine deformation does not generally allow suitable stratigraphic reconstruction, only a selection of the more representative sections will be described here. In the island of Hydra, the Permian succession, which consists mainly of carbonate platform sediments altemating with shales (Fig. 11), can be subdivided into four "Groups" separated from each other by tectono-sedimentary events [98]. On the basis of fossil data (foraminifers and algae), these events occurred: 1) in the late Asselian (onset of a first carbonate platform); 2) in the ?late Artinskian (uplift or tilting of the above platform with consequent erosion); 3) between the late Murgabian and probably the late Midian (as with the previous "Group", a palaeotectonic event affected a successor platform); 4) in the lower Dorashamian (deformation and erosion of a third platform, with a subsequent terrigenous influx). The presence of a gap at about the Lower/Upper Permian transition, and the intensity of tectonic activity during the Early Triassic, with consequent Permian olistoliths, are also worthy of attention. Among the above-mentioned events, the first generally seems to coincide with the inception of the younger Permian cycle in the Southem Alps and in other European regions, as well as with the formation of flysch-like deposits and olistostromes in western Sicily. The fourth tectonosedimentary event of Hydra can be related to environmental changes associated with important eustatic movements, as observed elsewhere [98]. This interpretation could be extended to the similar scenarios in Basilicata, Sicily, Montenegro, and the northern Julian Alps. Lower and Upper Permian shallow-marine blocks

61

Fig. 11. Synthetic Permian stratigraphic section of Hydra Island, Greece, with the distribution of the main Foraminifera. A - D: tectono-sedimentary events (see tex0. Atter Baud et a1.[98] slightly modified.

62 and olistoliths reworked into Lower-Middle Triassic sandy-shaly volcaniclastic successions also occur in Attica, north of Athens. On the island of Lesvos, near Turkey, Permian fusulinids and brachiopods have been found in intensively tectonized marbles and schists. In Chios the allochthonous unit of the northeast part of the island includes flysch-like deposits beneath carbonate platform sediments [99]; micropaleontological investigation has suggested that these sediments are correlatable with those of the Murgabian middle platform of Hydra [98]. The autochthonous sequence of Chios also consists of a flyschoid unit; as the youngest clasts in this unit pertain to the Upper Carboniferous [ 100] and since it is overlain by Lower Triassic deposits, this unit is generally ascribed to the Permian [99]. The Andros island also includes schists with intercalations of marbles that bear Early-?Late Permian fossils [ 101 ]. In Salamis and Crete, deep-water sediments also crop out. The fact that these outcrops occur from western Sicily to other more eastern areas of the Permian Tethys, and even as far as Japan, carries important palaeogeographic implications.

5. CONCLUDING REMARKS During the Permian, the Southern European regions examined in this paper are occupied by continental and marine domains. The former prevail to the west (Spain, Southern France, part of Southern Alps, etc.) and, generally, in the eastern Balkan areas, while the latter characterize Sicily, Greece, part of the Dinarids and the Carnic Alps. The continental realm is dominated by siliciclastic and igneous deposits. Diachronously emplaced in a "swell-and-basin" topography, these deposits resulted from a subsequent structural reorganization of the area affected by the Variscan orogeny. This reorganization clearly began during the Namurian and persisted up to the Late Permian and Triassic times. The igneous products formed intrusive and extrusive, locally widespread bodies. In Provence, Corsica, Pyrenees and elsewhere, this magmatic activity generally evolved from a calcalkaline acidic and basic suite to another one of alkaline bimodal composition, which developed in post-Autunian times, i. e. in the Early Permian p.p. and Late Permian. These latter magmatic activity is considered by the French authors to mark the beginning of the Alpine cycle. The Permian successions display unconformities of various types, duration and importance. In the Southern Alps, the stratigraphic discontinuity widely recorded below the Verrucano Val Gardena redbeds led us to subdivide the Upper Carboniferous-Upper Permian succession into two high-rank tectono-sedimentary cycles. The succession of the former cycle (lower or 1st cycle) infilled a number of narrow fault-bounded basins; the succession of the latter cycle (upper or 2 nd cycle) extended as an almost continuous blanket from Lombardy to the Camic Alps and Slovenia. Recent investigations [26, 30] assume that subsidence within mobile Lower Permian basins (locally slightly younger, even up to the onset of Late Permian) was mainly controlled by a progressive thinning in the Variscan crust and by strike-slip tectonics. In contrast, the deposition of the Verrucano/Val Gardena Fms. was the result both of a marked extensional tectonics and, probably, of a rifting regime. In the latter, subsidence evolved from tectonic- to thermal control, although local tectonics started at the end of Lower Triassic. The contrasting depositional geometries of the first and second cycle reflect this difference in tectonic regime.

63 The above-mentioned "Mid-Permian" regional unconformity has also been recognized in the Ligurian Alps, Spain, and Bulgaria. As a consequence, we emphasise that this bipartition is probably a widespread feature of the Permian successions in large parts of Europe, although they should not be considered as necessarly coeval. Undoubtedly, the significance of these changes can be interpreted as a crucial point in the geodynamic evolution of central Mediterranean and adjoining areas. As already stated, the Permian marine realm of South-Europe consists of evaporitic to shallow- and deep-water sediments. They were linked to the Tethys, but the Upper Permian (?) sabka deposits discovered in the Moesian Platform of Bulgaria and Romania could be also ascribed to the influence of a separated northern sea ("PalaeoTethys" sensu Seng6r) [102]. The presence of unconformities in the Tethyan areas is sometimes uncertain because of the lateral discontinuity in outcrops, erosion, Alpine deformation, and of the lack of detailed research. However, in some regions described (Greece, etc.), unconformities and gaps may be inferred from the Carboniferous to Triassic successions. The most representative events generally coincide with those yet again connected approximately with the Early/Late Permian tectonics, as well as with those recorded at or near the P/T boundary, as in the Southern Apennines, Greece, and other areas [80, 32, etc.].

Acknowledgements This paper represents a contribution to the IGCP Project No.359: "Tethyan, Circum-Pacific and marginal Gondwanian Late Paleozoic and Early Mesozoic correlation (biota, facies, formations, geochemistry and events)", to the activity of the "Continental Permian Working Group (S.P.S.)", as well as to the new Italian research programme on the "Late Palaeozoic stratigraphic and structural evolution in Alpine and Apenninic sectors. Comparisons with Sardinia and other areas of the Western Mediterranean". G. Cassinis and coauthors express cordial appreciation to Yin Hongfu for his invitation and help in preparing this summary. They also thank A. Ronchi and G. Santi for their assistance with the drawings. This work was supported by grants from C.N.R. and M.U.S.T. (40%, 60%).

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Persian-Triassic Evolution of Tethys and Western Circum-Pacific H. Yin, J.M. Dickins, G.R. Shi and J. Tong (Editors) o 2000 Elsevier Science B.V. All rights reserved.

71

The Permian of China and its interregional correlation Yugan J1N and Qinghua SHANG Nanjing Institute of Geology & Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China

Using a refined regional chronostratigraphic scheme for the Permian of China, a summary of the Permian stratigraphic framework in major depositional basins and a tentative correlation between the regional Permian sequences are presented. The Chuanshanian or Cisuuralian rocks in China, which used to be referred as the latest Carboniferous, are firmly defined. With helps of evidence from sequence stratigraphy, magnetostratigraphy and isotopic age, a more reliable correlation between the Lopingian rocks of different palaeobiogeographic regions is suggested. The currently most prominent difficulties of inter-regional correlation in China are closely related to the long-standing problems of international correlation, which are mainly caused by strong biogeographic differentiation between the Boreal, Gondwana and Pan-equatorial realms.

1. I N T R O D U C T I O N The earliest report on the Permian rocks in China was published in the eighties of last century[l]. Grabau made an attempt to set up the inter-regional correlation of Permian sequences in China in 193112]. Sheng [3] provided the first correlation chart for the Permian of major depositional basins in China, when he published a comprehensive summary on Chinese Permian. By that time, some 250 names of Permian lithostratigraphic units were presented, of which most are from North China and South China, only one tenth are from Xizang, Xinjiang and other remote regions. During the succeeding two decades, tremendous efforts were made in setting up local Permian sequences as a part of a country-wide geological mapping program at a scale of 1/200,000. Sheng et al. [4] compiled a correlation chart for the Permian sequences of forty-eight areas. In 1994, using a newly proposed Chinese chronostratigraphic scheme consisting of three series and 8 stages, Sheng and Jin presented a correlation chart of the Permian lithostratigraphic sequences of 83 areas in China. This paper is mainly designed to give a general impression of the Permian sequences in China. Only the dominant succession of lithological units and fossil zones, important lithofacies and biofacies changes in major depositional basins will be described.

72 2. C H R O N O S T R A T I G R A P H I C SUBDIVISIONS (Figure 1) The corresponding level to the GSSP for basal boundary of this system has not been identified in China. It can be approximately recognized in the slope facies or lower ramp facies of the carbonate platform in South China, which was defined at the base of the Pseudoschwagerina uddeni zone and the Streptognathodus elongatus-S, wanbaunsensis conodonts zone. In the outer shelf or lower ramp, the earliest occurrence of Occidentoschwagerina was taken as the indicator of this boundary. In the inner shelf facies, the genus Sphaeroschwagerina was often found in the bed directly overlying the Triticites noinskyi plicatus Zone, with no Occidentoschwagerina-bearing bed in between. In the shelf edge facies, early forms of Robustoschwagerina occur immediately above the latest of the Triticites zones, but below the introduction of species of Sphaeroschwagerina. In Central and Southem Xizang, the base of the Permian sequences is most conventionally marked by appearance of the Eurydesma bivalve fauna and a brachiopod fauna characterized by the occurrence of Stepanoviella or Bandoproductus. The indicative fossils of the base of Triassic System were proposed to be the earliest occurrence of Otoceras and Hypophiceras or that of Hindeodus parvus. The lithostratigraphic boundary between the Permian and the Triassic is approximately coincident with the major sequence boundary. In fully developed marine sequences, there is o~en a thin bed of the Changhsingian above the sequence boundary, such as the Mixed Bed 1 at the Meishan Section of Zhejiang and the Waagenites Bed at the Selong Section of Xizang[5]. The Permian is divided into three series, namely, the Chuanshanian, Yangsingian and Lopingian Series, and two subseries for the middle series, namely the Chihsian and Maokouan Subseries [6,7]. 2.1. The Chuanshanian Series.

This series was named by Huang in 1932 [8] and includes two stages, the Zisongian and the Longlinian Stage. The Zisongian Stage was originally designed to include the Pseudoschwagerina uddeni-P, texana zone and Sphaeroschwagerina genozone by Zhang et al. [9] with the Yangchang Section in Ziyun County of Guizhou Province as its stratotype. It contains three conodont zones, namely, the Streptognathodus waubansensis, the S. barskovi, and the Mesogondonella bisselli zones. The Longlinian Stage was suggested by Huang and Shi [ 10] as a new regional stage for the biostratigraphic sequence between the last appearance of Pseudoschwagerina and the first appearance of the genus Misellina. The reference point of the base of Longlinian Stage is delineated at the base of bed 23 of the Yangchang Section described by Zhang et al. [9]. It is marked by the first appearance of Pamirina divarsica. Since the lowering of the South China Sea became much more evident during the Late Chuanshanian regression, the dominant forms of the fusulinid assemblages were varied in different depositional sittings. They are characterized by a dominance of species of Nankinella, Staffella and Pamirina in the shallow inner shelf, by Pamirina and Chalaroschwagerina in the outer shelf and slope, and by Pseudofusulina in the shelf depression or in local basins [ 11 ].

73 2.2. The Yangsingian Series. Being named by Huang in 1932 [8], it corresponds with the stratigraphic sequence between the maximum regression occurring at the very beginning of Chihsian time and the commencement of the Lopingian transgression, or with two genozones, the Misellina zone and the Neoschwagerina zone. It used to be divided into two stages, the Chihsian and Maokouan Stage. Considering that the stratigraphic range of these two stages is so broad that actually corresponding to the Cathedralian and Guadalupian Series in USA, their ranks were upgraded as the subseries. Each subseries contains two stages: the Luodianian and Xiangboan Stage of the Chihsian Subseries, and the Kuhfengian and Lengwuan Stage of the Maokouan Subseries. The Luodianian Stage is proposed by Sheng and Jin [6] to include the stratigraphic range of the genus Misellina in outer shelf sequence. Usually, the Misellina genozone can be divided into the Brevaxina dyhrenfurthi, Misellina claudiae and Shengella zones. The type section of this stage has been proposed to be defined in the Yangchang Section with the base of bed 22 as its lower boundary [11]. However, it would be more suitable to place the reference point of this boundary at the base of Bed LNC106 in the Luodian Section [12]. The fossil succession from the Luodian Section is more complete, which includes three fusulinid zones, from Brevaxina dyhrenfurthi Zone to Misellina paramegalocula Zone, and conodont succession from the Neostreptognathodus pequopensis Zone, Mesogondolella gujioensis Zone to the M. idahoensis Zone. In the eponymous locality of the Chihsia Formation, in eastern suburb of Nanjing, the depositional sequence corresponding to the Brevaxina dyhrenfurthi Zone is absent or replaced by clastic beds, partly equivalent to the Liangshan Formation. The Xiangboan Stage was designed to contain the Cancellina Genozone[13]. The depositional sequence of this stage is best developed in the Houchang Section, Ziyun County of Guizhou Province[11]. The base of this stage is distinguished by the appearance of the primitive forms of Cancellina. Three fusulinid range subzones recognized at this section are the Cancellina elliptica, C. liuzhiensis, and Neoschwagerina simplex subzones. In the restricted shelf deposits, the fusulinids of this stage are usually dominated by Parafusulina multiseptata. This stage comprises the upper part of the Mesogondolella idahoensis and the Sweetognathodus hanzhongensis conodont zones. The Kuhfengian Stage was recommended for the stratigraphic succession from the base of Jinogondonella nankingensis Zone to that of the dr. postserrata Zone, with the Houchang Section as the reference section. The Kuhfengian fusulinids are grouped into the Neoschwagerina craticulifera and the Neoschwagerina magaritacea Zone. At the Sazhi Section in western Guizhou, from which the Maokou Formation was named, the fusulinids of this zone are dominated by Afghanella schenki. The ammonoids of this stage have been referred to the Waagenoceras Zone, the Kufengoceras Zone[14] or the AltudocerasParaceltites Zone [ 15]. This stage can be correlated with the Murgabian Stage of central Asia in terms of the fusulinid zones. The Lengwuan Stage was originally used as an extension of the Lengwu Formation in western Zhejiang, which contains the fusulinids Eopolydiexodina, Codonofusiella, Minojapanella, Reichelina and Metadoliolina, and conodonts of the Jinogondolella altudaensis, and dr. xuanhanensis zones. The base of the Lengwuan Stage is re-delineated at the base of dr. postserrata Zone in the Penglaitan Section of Laibin, Guangxi, which is

74 approximately at the same level as the first appearance of the genus Yabeina [ 16]. This stage includes a conodont succession from the Jinogondolella postserrata, J. shannoi, J. altudaensis, J. prexuanhanensis, J. xuanhanensis Zone to the J. granti Zone. 2.3. The Lopingian Series The name derived from the Loping Coal-beating Series [17] was firstly used as a chronostratigraphic unit by Huang [8]. Sheng [3] adopted the Lopingian as the upper series of a bipartite Permian and referred it to a series apparently higher than the Guadalupian Series, based on succession of fusulinids. This youngest series is characterized by the development of conodont genus Clarkina, fusulinids of Palaeofusulina-type, and ceratitid ammonoids. It includes two stages: the Wuchiapingian [18] and Changhsingian Stage [19]. The Wuchiapingian Stage has been widely used as a regional chronostratigraphic unit in the Late Permian in China since the lithostratigraphic and biostratigraphic successions were well studied. The Longtanian Stage [20] essentially covers the same stratigraphic range. It is not accepted because the originally defined lithostratigraphical unit of the Lungtan Formation consists of continental deposits and mostly falls within the Lengwuan Stage of the Maokouan Subseries. The base of the Wuchiapingian Stage is conventionally placed at the base of the Anderssonoceras-Prototoceras Zone and the "Clarkina bitteri-C, liangshanensis" Zone, usually overlying a terrigenous bed that resulted from a global regression. In an unbroken sequence from the Late Guadalupian to the Early Lopingian in the Penglaitan Section, Laibin County of Guangxi, three conodont zones, i.e. the Clarkina postbitteri, C. dukouensis, and C. asymmetrica zones occur below the C. liangshanensis Zone. The ammonoids associated with conodonts of the C. postbitteri Zone are referred to the Roadoceras-Doulingoceras Zone [21 ]. This stage is subdivided into the Laibinian and the Laoshanian Substages [22, 23]. The boundary between these two substages is redefined with the first occurrence of Clarkina leveni. The Laibinian Substage contains the Clarkina postbitteri, C. dukouensis and C. asymmetric conodont zones. The Laoshanian Substage embraces the C. leveni, C. guangyuanensis and C. orientalis conodont zones, and the Anderssonoceras-Prototoceras, Araxoceras-Konglingites, and Sanyangites ammonoid zones. The Changhsingian Stage was formally proposed by Zhao et al. as an international standard for the last stage of the Permian in1981 [24]. The D Section in Meishan was recommended as the stratotype of the Changhsingian Stage, while the base of the stage is located at the base of bed 2, the horizon between the Clarkina orientalis and the Clarkina subcarinata zones. The basal part of this stage is also marked by the occurrence of advanced forms of Palaeofusilina, and the tapashanitid and pseudotirolitid ammonoids. Two subdivisions of the Changhsingian Stage, the Baoqingian and Meishanian Substage, are recommended based on the proposed stratotype of the Changhsingian Stage in the Meishan Section. The boundary between these two substages is defined by the earliest occurrence of Clarkina changxingensis at the base of bed 13 of the D Section in Meishan, Changxing. 2.4. Correlation with the international standard Between the Chinese and the international standard Permian chronostratigraphic schemes[25] correlation of the basal systemic boundary, the basal boundary of the Artinskian Stage remain to be documented. And the corresponding level of the basal Guadalupian in the Tethyan Permian is a subject of debate. The Roadian Stage of the Guadalupian Series is proposed to be indicated by the first appearance of Jinogondolella nankingensis. In South

75 China, Kungurian and Guadalupian sequences were documented conventionally by the fine zonation of the fusulinids [12] and the conodonts [26] in South China,. The successive appearance of the Kungurian and Guadalupian leading species of conodont zones can be inter-correlated one by one between the slope sequences in the Loudian Section of South China [26] and the type section of SW USA. The base of the N. exculptus Zone is within the Pamirina Zone and therefore, the basal boundary of the Kungurian Series could be lower than that of the Bolorian Stage [12]. It was followed by the Mesogodolella gujoiensis - M.

Zonation

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Figure 1. Chronostratigraphic subdivisions for the Permian System of China [7].

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76 is an interval with a dominance of a shallow water conodont fauna, such as Sweetognathus subsymmetricus and Sw. hangzhongensis between the M. idahoensis Zone and the J. intermedia, M. idahoensis and then Jinogondolella nankingensis in both sections. But, there nankingensis Zone. It remains an open question whether the Sweetognathus subsymmetricus Zone is a counterpart of the upper M. idahoensis Zone or the lower J. nankingensis Zone in SW USA. Presuming that the Sw. subsymmetricus Zone corresponds to the lower part of the type J. nankingensis Zone, the associated fusulinids will belong to the Praesumatrina neoschwagerinoides Zone. General surveys on the Permian ammonoids show that Daubichites is widespread and is confined to the Roadian Stage. In South China, Daubichites was reported from the Tingchiashan Formation, which is definitely the Kuhfengian in age[14].

3. C O R R E L A T I O N

3.1. Stratigraphic-tectonic provinces During the Permian period, there were four major blocks, namely, South China, North China, Tarim, and Central and Southern Xizang [northern part of India Craton]. Permian deposits on these blocks are dominated by shallow shelf facies [Figure 2]. During the Early Permian, deep water deposition occurred on the continental slopes around the northern margin of the India Craton, the northwestern margin of the Tarim Craton, and possibly the southern margin of the Sino-Korean Craton. It also appeared in such micro-aulocogens as the Dian[Yunnan]-Qian [Guizhou]-Gui [Guangxi] Basin, Songpan Basin and the Qinzhou Trough. The oceanic sediments and faunas of Late Paleozoic age in the Qinzhou area may indicate the possibility of an allochthonous origin, and the huge thick diamictites of the Early Permian in Central and Southern Xizang have been interpreted as glaciomarine. Meanwhile, terrigenous sediments were deposited in the intercratonic basins caused by extension during Middle and Late Permian time. In between these stable cratons, there are two pronounced mobile belts and three others, which were mostly diminished by post-Permian convergence. The Northern China Mobile Belt, extending from Beishan to the northeastern comer of China via Nei Mongol, Hinggan and Central Jilin successively subducted southward and formed three latitudinally trending accretional zones. To its northwest, compression basins of terrestrial deposits were created in North Xinjiang with the folded Late Carboniferous rocks as the basement. The Beishan - Nei Mongol - Hinggan region collided with the Carboniferous folded belt of the Dahinggan Gobialtay block during Late Maokouan, and formed a set of terrestrial basins caused by further compression. The Permian sequence in the far-east of this mobile belt in China represents an island arc sea, which closed after the Maokouan. The Western China Mobile Belt, occupying the contact areas between South China proper and the Tarim, Qaidam and India block is a complex composed of numerous troughs, volcanic islands and micro-blocks. Among the volcanic island arc seas are those developed respectively along the eastern Kunlun Mts., the Jun U1 Mts., the Qinghai Nanshan, the Yalong River, the Jinsha River and the Lancang River. The micro-blocks comprise the Shuang Hu, the Hob Xil Shan, the Qamdo, the Markam-Batang and others, in which Permian lithostratugraphic and fossil sequences are essentially the same as those of South China. In addition of these two major mobile belts,

77 Permian rocks relating to the island arc belts are preserved in the eastern part of Taiwan Island and the western part of Southern Tianshan of Xinjiang as relics of respective convergent zones. 3.2. Biostratigraphic successions Paleogeographically, nearly all depositional regions of China fall within Paleotethys in a broad sense. In South China, Tarim, Qaidam and the micro-blocks scattered in the Western China Mobile Belt, carbonate-dominated sequences accumulated in tropical and subtropical shelf seas. The Permian strata commonly contain rich Tethyan faunas and Cathaysian floras. However, palaeobiogeographically mixed faunas and floras frequently occurred in the transitional areas. The Potonieisporites-Vittatina and Striolatospora-SchweiterisporitesCalamospora palynomorph assemblages from the Chuanshanian beds of northwestern Tarim show an affinity with the European phytoprovince. And the Ullmannia bronni-Yuania magnifolia Assemblage from the Shihchienfeng Formation of Lopingian in North China is characterized in the Zechstein of the Euramerican phytoprovince.

~-----...

/ /

/

/ //

IV1

IV3

j L~

//'

/

/

/

Figure 2. Stratigraphic-tectonic provinces of the Permian in China. I. South China, It SE China, 12 Jiangnan, I3 Yangtze, 14 Qing-Kang-Dian, 15 Tanggula-Hengduan, 16 Peri-Pacific; II Tarim, II~ Kelpin, II2W Tarim, II3 SW Tarim, 114 Qaidam; III North China, IIIl N Qilian, 1112 Daqingshan, III3 Jin-Ji-Lu, 1114 Huang-Hui; IV Northern China Borderland IV~ N Xinjiang, IV2 Beishan, IV3 Nei Mongol-Songliao; V Himalaya, V~ S Xizang, V 2 Yalung-Zangbo, V3 Gangdise, V4 Karakorun, V5 W Yunnan. Areas with cross-lines indicate major uplifts [27].

78 In Central and Southern Xizang, Permian sediments deposited in the peri-Gondwana seas are preserved, of which the lower group is made of clastics with floras and faunas closely related to the Gondwana Realm, and the upper group comprises mainly the carbonates and the fossils of Tethyan faunas. The Northern China Orogenic Belt with complex island arcs and troughs aligned on the northern margin of North China block accommodated Permian sediments of anomalous thickness with faunas and floras varying from Boreal to Tethyan affinities. In Xinjiang, Permian biostratigraphic successions are closely related to those of the Urals of Russia but are distinct from those of North China and South China. The succession of palynomorph assemblages has proven to be the most important criterion in correlation of the Permian beds throughout Northern Xinjiang since they can be readily recognized in various basins [28, 29]. Among these regions, the Permian sequences of South China have received more extensive study than those in other regions, and are regarded as a standard to which all correlation of the Permian in China are referred. However, faunas in the transitional areas between the Tethyan Realm and the Gondwanan or the Boreal Realm usually appear long-ranging, such as the Chuanshanian Eurydesma bivalve fauna, the Yangsingian Monodiexodina fusulinid fauna, and the Yangsingian and Lopingian Spiriferella brachiopod fauna.

3.3. Sequence stratigraphy Mainly based on data from North America and Russia, Ross and Ross[30, 31] referred the Permian sequences to a single second order cycle, the Transpecos Supercycle, consisting of about twenty-three third order cycles. They noted that two Wolfcampian cycles are closely related to the Tombstone Supercycle of the Pennsylvanian, and the post-Guadalupian cycle, to the upper Absaroka Megacycle. The eustatic curve drawn out by Holser and Magaritz [32] based on analysis of 68 major depositional basins shows three major regressions in the Late Artinskian, end-Guadalupian and end-Tartarian. Both eustasy curves decline gradually from the early Permian and reach the lowest point at the very end of Permian. On the other hand, with emphasis on importance of the sea level fluctuation in the extra-Pangea shelf seas, Jin et al. [16] interpret the Permian eustacy as one consisting of a complete supercycle between Late Artinskian and Late Guadalupian regressions and two partial supercycles, which are the Uralian sequence of the Pennsylvanian supercycle and the Lopingian sequence of the Triassic supercycle. Persistent overprinting on sea level-fluctuation in various blocks was imposed by tectonism during the Permian. First, the agglomeration of Pangea resulted in a differentiation of the shelves around low-lying micro-continents such as South China from the peri-Pangea shelves with appreciably higher geodesy. In extra-Pangea shelves, relative changes of coastal onlap during lowstand intervals are fully recorded, although the transgressive-regressive cycles during highstand times are less distinct. Second, gradual close of the Uralian and the Mongolian seas from the Kungurian to the Guadalupian epochs led to a steady elevation of continents in the northern hemisphere while the opening of tiffing seas around the northern margin of Gondwana and the North Sea caused a widespread regional transgression in the southern hemisphere from the late Guadalupian to the Lopingian. As a result of these tectonic influences, an up-tilt line can be traced between the profiles of sea-level changes for continents of the northern hemisphere and those for continents in the southern hemisphere.

79 Nevertheless, the following transgression-regression cycles can be recognized internationally after a careful evaluation of the tectonic influences. Chuanshanian TR Cycle. There is no dramatic sea level change at the beginning of the Permian, i.e. the early Asselian. A major sequence boundary and also a bio-evolutionary turning point is located at the base of the Carboniferous Kasimovian Stage. Asselian marine deposits are much more widespread than the preceding two stages but return to regression in the Sakmarian. In China, rocks of this sequence are referred to independent lithostratigraphic units such as the Maping Formation of South China and the Taiyuan Formation of North China. Yangsingian TR Cycle. The Permian sequence of South China comprises two major regressions that caused widespread erosional truncation (Figure 3B). The first regression appeared in early Artinskian [Pamirina zone or Charaloschwagerina zone in South China] and reached its acme at late Artinskian [9]. This regression also can be recognized in other blocks of Southern Tethys and peri-Gondwana. Usually, a continuous Permian marine sequence starts with the Artinskian transgression in these areas [33]. This sea level fall can be correlated to the major regression of the Late Artinskian revealed in eustatic curves as suggested by Holser and Magaritz [32]. It is divisible into two subordinate TR cycles corresponding with the Chihsian and the Maokou Formation. The end-Guadalupian regression started approximately in the upper part of the Jinogondolella. postserrata Zone, reached its lowest point at the top of the J. granti Zone and than shifted into the Lopingian transgression. Lopingian TR Cycle. Contrary to the traditional view that Late Guadalupian regression continued during the Lopingian, and accelerated near the Permian\Triassic boundary, the Lopingian sequences of South China apparently reflect a transgression system of the forthcoming supercycle (Figure 3A). Coal-beating deposits bracketed by basinal pelagic beds were developed in depressions behind carbonate platforms. These beds represent basinal floor fans deposited when these depressions were drained. Overlapping the coal-beating beds in shelf areas are marine beds with typical Wuchiapingian brachiopods, conodont faunas of the Clarkina leveni Zone, and ammonoid faunas of the Anderssonoceras-Prototoceras Zone, which form a widespread transgression surface. The Lopingian sequences above the transgression surface consist of a transgression system despite a relatively greater regression that occurred at the Wuchiapingian\Changhsingian boundary. The erosional surface caused by this regression divides the Lopingian sequence into two third-order cycles. A close study of lithological changes in tens of sections on the Yangtze craton shows the Wuchiapingian cycle comprises two secondary cycles, and the Changhsingian cycle, two and half secondary cycles[20]. A transgression Lopingian sequence in South China is not just a local development. It is consistent with conditions all over the Tethyan area including the Salt Range, Kashmir, Xizang, Japan, Iran, Southern Alps etc. during the Lopingian Epoch. End-Changhsingian transgression. With the progressive transgression during the Changhsingian stage, condensed deposits dominated by cherty shale of the Talong Formation occurred in basins and outer shelves. The sea level rose to a greater height than during the three previous cycles of the Lopingian. Surprisingly, following the Lopingian there is not a great regression as predicted by most popular models of Permian eustacy. In contrast, a rapid transgression appeared in the latest Changhsingian and was accompanied by a sudden endChanghsingian flooding. Carbonate accumulation on the middle and outer shelf was replaced

80 by condensed deposition. Coincident with this rapid transgression, up to 90% of the Changhsingian marine biota does not extend upward into the topmost part of the Changhsingian. It is noteworthy that similar acritarch assemblages have been found in the Goudikeng Formation, a transitional bed between the latest Permian and the earliest Triassic red beds in both slopes of Tianshan, Xinjiang [28]. Coastal deposits with marine bivalves and acritarchs dated as earliest Triassic also appear in between red beds in the southern part of North China. In southern Xizang, Changhsingian marine deposits occur below the Otoceras Zone of the basal Triassic. These occurrences indicate that the end-Changhsingian transgression had climbed to the lower lands of Tarim and North China from which sea water had been withdrawn in Artinskian time. 3.4 Magnetostratigraphic sequence Permian magnetic polarity zones are referred to two magnetostratigraphic superzones, namely, the Carboniferous-Permian Reversed Superzone and the Permian-Triassic Mixed Superzone (Figure 1). Chuanshanian magnetic polarity zones are referred to the CPRS. Normal magnetic polarity horizons have been identified in the Jinci Sandstone and the Ximing Sandstone in the lower part of the Taiyuang Formation in Shanxi, the Pseudoschwagerina and Sphaeroschwagerina Zone of the Maping Formation and in the Chihsia Formation in Yishan County of Guangxi [34]. Xia et al. [35] found a succession with 9 alternative normal and reversed polarity horizons in the Chuanshanian strata in Zheng'an County of Shaanxi. The Guadalupian and Lopingian magnetic polarity zones are referred to the PTMS. Its base is named as the Illawarra Reversal, and located in the Yats Formation in SW USA, which is usually dated as Late Guadalupian. It is identified in the upper part of the Maokou Formation in Wulong County, Sichuan [36], which is correlated with the Yabeina Zone of the Lengwuan Stage. In North China, the Illawarra Reversal occurs in the Upper Shihotse Formation [37]. With calibration of biostratigraphic zonation and isotopic ages, the Permian part of the Permian-Triassic Mixed Superzone [PTMS] can be assembled into four zones [38]. The N2P Zone ranges from the uppermost Kuhfengian Stage to the Jinogondolella altudaensis Zone of the Lengwuan Stage and is represented by two normal polarity horizons and one reversal between them. The top part of the Lengwuan Stage and the lower part of the Wuchiapingian Stage are dominated by reversed polarity and, are thus referred to the R2P Zone. The N3P Zone consists of at least four normal polarity horizons and ranges from the Clarkina guangyuanensis Zone of late Wuchiapingian Stage to the lower Changhsingian Stage. The upper Changhsingian Stage is assigned to the R3P Zone, which combines two reversed and one normal polarity horizons in between. 3.5. Radiometric age Major advances on isotopic dating of the Permian have been achieved recently. Dating of samples from the Urals suggests that the age of the mid-Asselian is 290 + 3.0 Ma, and that the Sakmarian/Artinskian boundary is 280.3 + 2.5 Ma. These results suggest an age of 296 Ma for the Carboniferous-Permian boundary (Figure 1).

81 For the Permian-Triassic boundary bentonite bed of the Meishan Section, a SHRIMP age of 251.2 + 3.4 Ma and 4~ age of 249.9 + 1.5 Ma have been provided. A recent study on isotopic age of the Changhsingian bentonite beds in South China yielded a reliable date of 251.4 + 0.3Ma for the boundary bentonite bed, 253.4 + 0.2Ma and 252.3 + 0.3Ma respectively for the base and the upper member of the Changhsingian Stage. Since the age of zircons from a bentonite bed just below the base of the proposed Capitanian stratotype is 265.3 + 0.2 Ma [39], the age for the basal boundary of the Lopingian Series is estimated as 259 Ma.

4. REGIONAL STRATIGRAPHY 4.1. South China (Figure 3) Generally, there are two major deposition regions during the Permian Period in South China: the Yangtze and the Huanan region. The core parts of the Yangtze region are craton areas which emerged aider Caledonian orogeny and submerged as epeiric seas until the Early Luodianian. The micro-aulocogen-type basins and the outer-shelves surrounding the Yangtze platform are referred to the Dian [Yunnan]-Qian [Guizhou]-Gui [Guangxi] Basin. The Huanan Region comprises the shelves on the Cathaysia massifs around the southeastern coastal areas, and the Jiangnan Basin. The latter consists of a series of depositional units, from north to south, including the Loping depressions, the Chengzhou, Liuzhou and Qingzhou basins. As the deepest basins of Permian sedimentation, they contain the most complete Permian sequences in South China. These basins located along eastern and northeastern margins of the Yangtze craton and were structurally controlled by the development of the Cathaysia craton in a great extent during the Late Permian. However, the oceanic sediments and faunas of Late Paleozoic in Qingzhou area also indicate the possibility of an allochthonous origin. The Zisongian deposits are exclusively composed of carbonate facies and are conventionally named as the Maping Formation in the Yangtze Region, or the Chuanshan Formation in the Huanan Region. A range of rock types from dolomites, white packstone and grainstone to black wacksteone and packstone accumulated respectively on shore, inner shelf and outer shelf. However, as a result of frequent sea level change, the most common sequences are alternating white and black limestone beds, and alternating dolomite and limestone beds. The global regression occurring during the Longlinian and Luodianian Stage induced strong facies differentiation. The Longlinian deposits mainly consist of interbedded shale, siltstone, bauxitic clay beds and thin-bedded limestone with a thickness usually less than 20m. Being characterized by development of the eluvial deposits, they were accumulated around erosional areas of the Jiangnan, Kangdian, and Yunkai massifs and on the core part of Yangtze Massif. Deltaic facies composed of sandstone up to 250m thick and containing minable coal seams were well developed surrounding the southern and eastern sides of the Yangtze Massif, and also the northeastern side of the Jiangnan Massif. Thick sequences with alternating carbonate and terrigenous beds were accommodated by a mini-graben in western Guizhou.

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83 The Early Chihsian deposits consist of argillaceous carbonate sequences on the inner shelf while those in the outer shelf and basin are much the same as the Longlinian facies. Then, aggregation during the highstand stage of the late Chihsian resulted in strong differentiation in facies. Depositional sequences that formed in depressions are dominated by alternating beds of shale and thin-bedded limestone, and those on submarine highs by nodular limestone and a characteristic brachiopod fauna with abundant and diverse forms of Cryptospirifer and such fusulinids as Neoschwagerina simplex, and Verbeekina grabaui. The latter are deposits of an intertidal environment with alternate deposition of carbonate shoals and mud fiats; its dispersal areas are more or less coincident with the eluvial and deltaic deposits of the Longlinian Stage. The sequences shift into the outer shelf dolomite facies [the Maokou Formation]; reef facies, for example, the Xiangbo Reef along the shelf margin; and cherty limestone in local basins. At the beginning of the Maokouan, the pattern of facies distribution in the eastern area was remarkably changed. The predeltaic and basinal deposits [the Kuhfeng Formation and its allies] accumulated in basins behind carbonate platforms during the emergence of the Cathaysia Uplift which consisted of a set of submarine highs. Lithologically, they are marked by having rich chert, phosphate nodules, stony coal beds and manganese carbonate beds, and coastal coal-beating deposits in the upper part. They are bounded by a disconformity at the base, which is possibly coincident with the maximum flooding surface, and gradually shift into deltaic facies or patch-reef facies upward. The isolated reef limestone that occurs in western Zhejiang was designated as the Lengwu Formation. The eruption of the Omeishan Basalt was a prominent feature of Late Maokouan and Early Lopingian in South China. This volcanic group spreads over eastern Sichuan, western Guizhou and eastern Yunnan and extends to the Panxi Rift Belts between South China and West China. The total area covered by the Omeishan Basalt approaches 330,000 square km. The average thickness is 705m and the total volume of volcanics is about 280,000 cubic km. The volcanic rocks rest directly on the Maokouan limestone, often with a residual clay bed tens of centimeters thick in between. Marine clastic beds or limestone intercalations with such fusulinids as Metadoliolina sp., and Neoschwagerina douvillei occur in the basal part of the basalt in eastern Yunnan, and western Guizhou. They are mostly continental volcanic sequences, except for the area near the tiffing belt on the west, in which the basalt shift into marine facies. Above the basalt is the Hsuanwei Formation, a coal-beating unit. The basal contact is unconformable in the western areas, and conformable in the east where it may include intercalations of basaltic lava and tuff beds. It changes laterally into the inner shelf facies represented by the Wuchiaping Formation and subsequently the Changhsing Formation, and then into basinal facies of the Talung Formation. The Changhsingian deposits consist of black laminated wackestone accumulated in slope environments; also thick-bedded, massive, light-colored packstone and grainstone that represent the deposits of carbonate shoals and reefs; and sequences dominated by dolomite and dolomitized limestone representing back reef facies. Platform deposits consist of shale and cherty beds. In slope and basin environments, the Changhsingian volcanic clay or ash beds were deposited. The Permian in the Qinzhou area is distinct in China, as it includes a pelagic shale sequence from the Zisongian Stage to the Lengwuan Stage in its lower part, and a fluvial to paralic clastic sequence of the Changhsingian in its upper part. Between these sequences is an

84 angular oceanic terrains China,

unconformity. Zonation of radiolarians is closely comparable to coeval tropical deposits represented by banded chert with highly diverse fossil radiolarian from the in circum-Pacific regions such as southern Japan, the Philippine, western Yunnan of and Oregon, USA. In Japan, the radiolarians of the Follicuculus charveti, Neoalbaillella optima and N. ornithoformis zones are correlated respectively with the Lepidolina kumaensis, Nanlingella simplex and Palaeofusulina sinensis zones [40]. This correlation indicates that the radiolarian succession in the Qinzhou area ended in the Changhsingian.

4.2. North China (Figure 4) The transgression of epeiric seas initiated in the Moscovian of the Late Carboniferous and swept over most parts of North China in the Zisongian. The post-Zisongian deposits of the Permian represent a gradual regression and are exclusively composed of terrigenous sediments ranging from paralic to inland basinal facies. The rock types are uniform over wide areas and are interpreted as indicating the presence of a peneplaned platform with uptilted northern and northwestern margins, tectonically comparable to the present-day Andes. Distribution of major facies is parallel to the latitudinal trending Yinshan Uplift. The continual raising of the Yinshan Uplift along the northern margin resulted in successive migrations of the coal-bearing deltaic system southward. Consequently, the main stratigraphic levels of the minable coal seams form important characteristics of the Permian sequences of each lithological province. The Permian sequence in the areas around the southern margin of the Yinshan, the equivalents of the Taiyuan Formation are composed of alluvial and fluvial deposits, with a few thin beds of limestone at the top. Early Zisongian fusulinid assemblage consisting of Staffella and Nankinella was reported from the upper part of this formation [41 ]. The main minable coal measures occur in a stratigraphic position corresponding to the upper part of the Taiyuan and Shanxi Formation. In central areas, the Permian part of Taiyuan Formation contains two major depositional cycles. The Permian conodonts from the Taiyuan Formation are included in the Sweetognathus whitei Zone and the Streptognathodus elongatus- S. wabaunensis-S, fuchengensis Zone. The overlying Shanxi Formation contains three main depositional cycles each of which begins with a fiver bed sandstone and ends with lacustrine fine-grained clastic beds. Development of widespread bauxite clay beds in the top part of the Lower Shihhotse Formation indicates a possible erosional surface. The succeeding Upper Shihhotse Formation forms the lower part of a major depositional cycle and the frequent occurrence of cherty beds composed of sponge spicules in this formation implies repeated inundation by sea water. It contains the Gigantonoclea hallei - Fascipteris spp. - Lobatannularia ensifolia Assemblage of fossil plants, an equivalent of the flora from the Lungtan Formation of the Late Guadalupian and Early Lopingian in South China. In the southern areas, the intercalated beds of limestone of the Taiyuan Formation may be up to twelve. The main minable coal seams occur in the Lower Shihhotse and the Upper Shihhotse Formation, which formed a shallow-water deltaic system; these are absent in the northern and central sectors. Thin cherty beds composed of sponge spicules appear in the Upper Shihhotse Formation, occasionally accompanied by Lingula. The appearance of palynofloras with a few acritarchs and other marine fossils in the Shihchienfeng Formation in

85

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86 the southem belt has been interpreted as an indication of an inundation phase of the Changhsingian Stage [ 16]. In Taiyuan of Shanxi Province, the Illawarra Reversal is identified in the lower part of the Upper Shihhotse Formation t371. The upper part of this formation is dominated by reversed polarity and thus, agrees with the Wuchiapingian reversal polarity zone. As with the latest Wuchiapingian and the Changhsingian marine sequences, the topmost of the Shihhotse Formation and the Sunjiagou Formation reveal a prevalence of normal polarity. In Northern Qilian, Permian rocks form an east-trending narrow strip around the southem margin of Tenggar Desert and the eastern part of Beishan, including from west to east, the northern part of the Qilian Mts., the Longshoushan Mts. and probably the westem part of the Helanshan Mts. The lithological and biostratigraphic sequences are comparable to those of the North China Region proper. However, they are almost entirely composed of continental deposits with the exception of a limestone bed with brachiopods and rare fusulinids at the top of the Taiyuan Formation. There are virtually no coal measures in the Permian rocks in spite of a few thin coal seams in the Taiyuan Formation. The rest of the Permian sequences is exclusively dominated by red bed facies, variegated, green and red shale, lithic sandstone and conglomerates, all of alluvial origin. One of the striking characteristics of Permian fossils from this area is that plant fossils from the uppermost Permian contain elements of the Angaran phytoprovince, a feature now considered to denote the boundary between the Cathaysian and the Angaran phytoprovinces.

4.3. Northern Xinjiang (Figure 5) The Permian in Northern Tianshan, Junggar Basin and Altay Shan are essentially composed of continental deposits. Permian sediments in the intermontane basins of the Altay and northern Junggar Mts. overlie unconformably pre-Bashkirian strata. They are characterized in the lower part by volcanic facies, which consist of andesitic to rhyolitic lava, tufts and alluvial-fluvial sandstone and conglomerates containing volcanic detritus. Plant fossils of the Angaropteridium-Zamiopteris Assemblage from the Chuanshanian tuffaceous deposits in northern Junggar which is characterized by the occurrence of Zamiopteris and the "Noeggerathiopsis" derzavinii and N. latifolia, are comparable in composition to the flora of the Upper Balakhonsk Group in Russian Altay. The upper part of the Permian sequence includes fluvial and lacustrine deposits with coal seams, which mostly accumulated in small grabens that appeared during the Early Permian. Permian sequences at the southern margin of the Junggar Basin are comprised of sediments accumulated in a back arc basin, and usually overlie Gzhelian beds with an unconformity. In the type area, the suburb of Urumuqi, the nine Permian Formation are conventionally assembled into three groups: the Lower Chiechietsao, the Upper Chiechietsao and the Tsangfanggou Group, which are dominated respectively by coastal, lacustrine and alluvial deposits. The Lower Chiechietsao Group is composed of a fining-up, transitional sequence from shallow marine to estuarine facies. The lower part of the section here contains rhythmic paralic deposits which are replaced upwards by fluvial deposits. A return to coastal lacustrine conditions occurred in the Lucaogou Formation of Maokouan age, which is the most widespread of the Permian units that appear in the Junggar Basin and its neighboring basins. The Lucaogou Formation include fish fossils Turfania taoshuyuanensis, Ulumqia liudaowanensis, Chichia gracilis, etc., bivalves are Anthraconauta, Mrassiella, Microdonta, and Palaeodonta,

87

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88 and ostracods Tomiella, Permiana and Darwinula. This formation is succeeded by red bed facies of the Lower Tsangfanggou Group and than by a brief expansion of lacustrine deposition of the Goudikeng Formation at the end of the Permian. The two phases of the dominance of lake facies are possibly correlated with the Kuhfengian and the end-Permian flooding in South China. The Lower Chiechietsao and the Upper Chiechietsao Groups contain micro-floras dominated by striate disaccate pollen Hamiapollenites, Striatoabieites and Striatoparvisaccites or the monosaccate pollen Cordaitina. Occurrence of the Dicynodon vertebrate fauna from the Tsangfanggou Group confirms an age of the Late Tatarian. A micro-flora containing Aratrisporites, Lundbladisporites, Lueckisporites virkkiae and Taeniaesporites from the lower part of the Goudikeng Formation indicates the latest Tatarian age. Paleomagnetic studies on the Permian sections of this area have been undertaken repeatedly. The normal polar zone probably corresponding to the Illawarra Reversal was located in the upper part of the Lucaogou Formation. Two normal polarity zones were detected respectively from the Wutonggou and the Goudikeng Formation. This fact suggests that the middle part of the Hongyanchi Formation and the upper part of the Lucaogou Formation belong to the Maokouan Subepoch. 4.4. Tarim The Permian of Tarim consists of a transgression sequence of the Chuanshanian and a regressive sequence of from the Yangsingian to the Lopingian. The Chuanshanian shallow shelf carbonate deposits developed over most of the Tarim platform. The distribution of shoal sandstone and grainstone indicates the presence of an uplift extending from Wushi to the southeastern corner of the platform. To the west of this uplift are the dolomites and wackstone of the inner shelf, and then, the packstone and grainstone of outer shelves. The subsequent Permian sequences are mainly composed of continental deposits with the coastal deposits in the western, and the fluvial deposits in the eastern. In Kalpin of northwest Tarim, Permian carbonates deposited in a rimmed shelf, which shifted northward to the troughs of Southern Tianshan (Figure 6). The Chuanshanian carbonate beds overlap eastward on to the Devonian and older beds, and are exclusively named as the Kankarin Formation. To the west they are replaced by reef facies that are scattered around the shelf margin, and rest conformably on Late Carboniferous beds. Further to the west are thick flysch that indicate the troughs surrounding the northwestern border of the Tarim platform. After a regression in association with sea level lowering of the Longlinian, the former shelf margin and slope area was covered by a shallow embayment in which calcareous fine-grained clastic beds of the Sarezhiyi Formation were deposited, and a delta system developed on the site of the previous shelf areas. The deltaic sequence, namely the Kalender Formation, contains thin coal seams in the upper part and is overlain by the basalt trap [42]. In southwestern Tarim, a relative broad carbonate shelf developed from the early Late Carboniferous to the Late Longlinian (Figure 7). The Qipan Formation with Neostreptognathodus sulcoplicatus (Youngquist, Hawleym et Miller) should be assigned to the Chihsian since this species appears first in the Cathedral Formation of the U.S.A. while the Kiziriqiman Formation, should be assigned to the Sakmarian, as it contains Neostreptognathodus pequopensis, a species that appears first at the base of Neal Ranch

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Figure 6. Generalized stratigraphic sections of Permian deposits in Kelpin area, northwest Tarim showing Chuanshanian marine sediments thinning eastward, and post-Chuanshanian terrigenous sediments thinning westward.

Formation. Continental Permian rocks crop out in areas north of Hotan County and west of Yecheng and Sache Counties. Commonly, they rest conformably on the marine beds of Late Carboniferous carbonate beds and comprise alternating sandstone and siltstone [43].

90

A

SOUTHERN TARIM

Kaplanggou Qipan II I

Hotan III

[-1~"

,-400m

i/

l

l00

TARIM

B

QAIDAM Yesanggan Aqqikkol QimanTag Golmud Lake

~ ~ i ~ ' '~-j, iu150

SOUTHERNQILIAN Toson Lake VIII Delingha Menyuan

':}i2

300km

Jiuauan .

QII_. 9

I

~l~v

QINLING

Hanzhong

conglomerate sandstone

graywacke

siltstone

limestone

basalt

Figure 7. Fence diagram across the rimming shelves respectively around the southern margin of Tarim, Qaidam and Qilian, showing the thickness and facies relationships of Permian deposits.

4.5. Beishan - N e i M o n g o l - J i l i n (Figure 8) This region includes, from west to east, the Beishan in northern Gansu and eastern Xinjiang, most of Nei Mongol, and the northern part of Northeastern China. In general terms the Permian may be divided into two major sections: a Yangsingian sequence composed of marine volcanics and volcanic derived sediments, underlying a Late Yangsingian to possible Lopingian sequence of finely banded argillite, and massive sandstone and conglomerate. Following migration of the collisional axis towards the southeast, the progressively retreating depositional sequence from northwest to southeast were successively accumulated in Beishan, Nei Mongol - Hinggan, and eastern Jilin. In the Beishan area, Permian rocks are characterized by a dominance of Yangsingian basaltic and clastic deposits that lie unconformably over the strata older than Moscovian age and lacks Chuanshanian deposits. Marine faunas are usually dominated by brachiopods and ammonoids but do not contain fusulinids. Paleogeographically, this belt represents a marginal arcwhich ended by early Maokouan time. Behind this volcanic arc is an elongate back-arc

91

Jinta

Stages

....... ~., ~.... Gansu i

Jisu Neimongol

II

Xi U j i m q i n Ulanhot N e i m o n g o l III N e i m o n g o l

C'ontral f i l i n IV! "-"~ ~ V

i i ', ', ', ', i

', :--""--"-""--""-- :--- -- ----" ~-.-. --". -- --'" Ka~shantun." ~?.

Changhsingian

:~-gsh~ou~m:

Wuchiapingian

""~'"e"e"e"r"r"r"f"

Lengwuan

........

- - 7_: __i t ~ a n g l m g o u r m | ~ Q i n g o u z h

,

',
.....

- ....

/

-!: : -i" -~. . . . . . .

t : - : - - - - F m ---7-~7-~ .. ...'. :. .:. . . .. . . . .

~'-: ; J i, n t a F m, ' ~ " . . . _. .

"-

L--'.-_" __" 7 - _ -

.~

i

----------

"

Luodianian

. :-.-.-.

~/,",',i',",'~:

:~''

~_~......... ~....... (....' .... ~ 7--7. ".'_.'-.'_'.-.'_" [--MiaolingFm-

i

9

! .............

-<_ I

/~/\/~/x/~/~;/~/~/~/\/\/~

-(

I Fm-

I....~'--s---[

7

i i

i

i

i

i

i

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i

- - B a o t e g e F m "--2" ~.~)(`:.~.?~:`~(~`~?:~.`.`.~..~:.~.~:`.C~:)..~:).~:`:.~?L,``.~`-`-`~```~'~

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Shuangputang F

m

)

[

~

i [

/

i

[

............ - - - =- - ~ - ~ - ==-I ~............ : "-AmushanFm-. )..I..~:: , Ganquan Fm, _ _ ............ [[][[SSI[3". ". . [ i A m u s h a n F m l /\ ......... I ~ " /~/~/\/\/\

Zisongian

"c~--q

"-~l:--Wujiatun Fm . . . . . . . r '-4m . .. . . ._. . . .[. . ~ _ . _ :--~-.._~._- - ~-Xiuj'imqin'F-n~ ~ ........ ] ....... :'~ -u.anj.mtun

~..Jus~litan l~m - ' ~ ...... ;" ......... 9 I 9 , 9 '" ," "," "~ "~.'. "-". 3egeng'a~176

Xiangboan

i

"7." ." ." . "~qSolon V m ~ -L-L------_] ''rS'ZTT' '' Fm_ .............. - ~. . . . . . . . " ~ "~ . . . . ., .. ., . . . . . r .Kedao F m ~ . . . ." " " - 9- ~ - B a o e r ' a o - . . . . . . . . .......... i-. - / " , ,.......... 9 " Yllaxl rm2___~ j: I .......... ~ 9 9oao r m ' ~. . . . - " .... '

................... ..... ~ i s u " ............ Kuhfengian

VI

I.k.%1!.

17".--" - - s

.............

Yanbian Jilin

-!

1, ! . . . . .

, I ....... , ;

/

houshan.g_ou F.m t;:---:-:--4 .......... ~.2.L7.',_1

I'?'-i-s

, I_:_-_:_-_:

!

" "

:

~

L.~LI . . . . . . . . .

onanA,u,,,~ H._~_ShizuiziFm-~ ............

!

"

..........

............

--1------%: - ~ ' - - - - - - - - ,

A

conglomerate

B

~

sandstone

'

-

graywacke

'

-

volcanics

~

J

limestone

J

Figure 8. Correlation of Permian successions in Beishan - Nei Mongol - Jilin region. Conformable relationships are indicated by straight lines, disconformity by dash lines, unconformities by saw-tooth margins, faulted boundaries by dotted lines, and facies boundaries by oblique straight lines. Hiatuses are marked by vertical shading, but with a question mark if the time interval of hiatuses have no precise biostratigraphic control.

92 basin filled by voluminous terrigenous deposits of Yangsingian and Lopingian age. Permian deposits in the main part of Beishan can be divided into three belts. Those in the areas around the China-Mongolia border are closely related to the Permian of Gobi-Tianshan in Mongolia that are composed of continental deposits of Yangsingian and Lopingian age. Permian deposits that occur in the central part lack volcanics. The ammonoids from the Shuanputang Formation contain Late Longlinian species of Uraloceras, Neocrimites, Demarizites and Propinacoceras, and those from the Juoshitan Formation were identified as species of Waagenoceras, Strigogoniatites and Stacheoceras[44]. In the Nei Mongol-Hinggan region, Early Chuanshanian and Yangsingian depositional basins developed in south of a marginal arc. Zisongian rocks are usually exposed as isolated outcrops, and comprise medium to fine grained flysch with limestone up to hundreds of meters in thickness, but no volcanic facies. Zisongian fusulinids are subdivided into the Pseudoschwagerina-Alaskanella linearis and the Sphaeroschwagerina borealis-S, texana Subzones. The Longlinian deposits (the Hugete Formation) are always associated with the Yangsingian sequences; both of which are predominated by medium- to fine-grained graywake-type accumulations with thick limestone. The occurrence of fusulinid Laxifusulina and the primitive Misellina in this formation suggests a Longlinian and Early Luodianian age[45]. The youngest marine beds, i.e. the Jisu Formation are dated as Late Kuhfengian based on the brachiopod Aulosteges-Vediproductus Assemblage [46, 47]. The Late Permian continental deposits, namely, the Linxi Formation are limited in the eastern part and show a span of lacustrine facies shifting from the coarse clastics in the northwestern part to very fine, thin bedded shale in southern and eastern parts In Great Hinggan Mts., the Yangsingian sequences usually begin with submarine volcanics, mainly andesite lava and pyroclastics, and are followed by coarse- to medium-grained flysch, or limestone breccias, which represent a carbonate bank formed atop a sea mount. Frequent occurrence of the fusulinids Pseudodoliolina ozawai, and Monodiexodina mashubaishi, and the ammonoid Doubichites suggest an early Kuhfengian age. The Linxi and the Solon Formation represent a lacustrine complex ranging from marginal sequences dominated by alluvial conglomerate beds in the lower part to graded fine-grained clastics such as shale and siltstone. In the Jilin area, Chuanshanian sequences are composed of thick-bedded limestone or limestone interbedded with fine-grained terrigenous beds containing fusulinids of the Pseudoschwagerina and Triticites Zones. Fusulinids of the Neoschwagerina Zone have been reported from the central and eastern parts of Jilin Province [48]. This fauna includes species of Neoschwagerina, Codonofusiella, Kahlerina, Sumatrina, Verbeela'na, Dunbarula and primitive forms of Yabeina. The Kedao Formation of eastern Jilin Province contain Yabeina multiseptata Deprat, Y. gubleri Kanmera, Metadoliolina lepida [Deprat] and various species of Parafusulina [49]. Both the Yilaxi and Yangjiagou Formation are composed of andesitic tuff and tuffaceous sandstone, pebbly sandstone and siltstone. The Yilaxi Formation contains a few fossil bryozaons, and the Yangjiagou Formation represents the upper part of a regressive sequence in marginal facies, and contains the bivalves Palaeomutela, Myalina and

Paleoanodonta.

93

4.6. Xizang [Tibet] (Figure 9) Like the other parts of the Himalayas, Permian rocks in southern and cemral Xizang generally contain two distinct lithological groups. The lower group is mainly a terrigenous series commonly marked by the presence of diamictites in the lower part and by dominance of sandstone and shale in the upper. The upper part is essentially a carbonate succession increasing in thickness northwards. The gradual change of lithological facies of both the lower and upper groups indicates that they have been deposited respectively in inner shelves, outer shelves and shelf slopes of an epicontinental sea along the northern margin of the Indian Continent [50]. In southern Xizang, the brachiopods referred to the Stepanoviella Assemblage were obtained from the top part of the Jilong Formation, a unit of diamictite beds in the Mt. Qomolongma region [51 ]. Stepanoviella is regarded as a diagnostic form for the fauna from the Umaria Marine Bed and its equivalents. The upper part of Permian sequences contains relatively less carbonate rock, and usually consists of coquina and biospararudite limestone with debris ofbrachiopods and crinoidal stems as the main biogenic components. Recently, it was confirmed that the Late Longlinian ammonoid Uraloceras [51] comes from the base of the Qubuerga Formation. The Changhsingian conodonts such as Clarkina changxingensis (Wang et Wang) and the Waagenites barusiensis-Paracrurithyris pygmae brachiopod assemblage were found from the beds around the Permian\Triassic boundary in the Selong Section, Nylam of Xizang [5]. This fact suggests the presence of Late Changhsingian beds definitely below the Otoceras Zone. In central Xizang, Permian sequences are characterized by the prevalence of biomicrite with foraminifers as its main bio-component in its upper part, and the occurrence of volcanic rocks in the lower part of very thick diamictite. They are mainly exposed in Pondo, Lhunzhub County, Yungzhu, Xainza and Dorma, Rutog County. In the Dorma area, Permian rocks were firstly reported by Norin [52]. He divided the Permian sequences into two groups, namely, the Tashliqkol Series in the upper and the Horpatso Series in the lower. However, both of these two series have not been used in subsequent reports since their definition is too broad. In terms of lithological and fossil content, the Tashliqkol Series essentially corresponds to the Lungmuco Formation and the Tunlunggongba Formation on the south of the Lungmu Lake, the Tunlunggongba and the Qude Formation in Domar, Rutog County, whereas the Horpatso Series corresponds to the Zhanjin and probably the Camong Formation in Dorma. The Cyrtella nagmagensis Assemblage including Syringothyris nagmagensis Bion, Neospirifer ambiensis (Waagen), Subansiria ranganensis Shani et Srivatava and Paekelmanella sp. occurs in the bed between the Monodiexodina Zone of the Tunlunggongba Formation and the Eurydesma Assemblage of the Qude Formation in Dorma. This assemblage is considered to be Late Asselian to Sakmarian. The fusulinids from the Lungmuco Formation consists of Triticites altus Rosovskaya, Eoparafusulina pusilla (Schellwien) etc., which suggest the Sakmarian in age. Thus the underlying diamictite and volcanic beds of the Lungmuco Formation should be pre-Sakmarian. The succeeding fusulinid-bearing beds in the Lungmuco Formation are characterized by such Longlinian forms as Pamirina chinlingensis (Wang and Sun), Schwagerina tschernyschewi (Schellwien), Pseudofusulina crassispira Zhang. Permian rocks exposed on the west of the Lancang River (the upper reaches of the Mekong River) are closely related to the Permian in the Shan State of Burma. The Dingjiazhai and the

94 Woniusi Formation form a depositional sequence separated from the underlying Lower Devonian rocks and the overlying Permian carbonates. Occurrence of the fusulinids Eoparafusulina sp., Nankinella sp. and Pseudofusulina sp. in limestone lens of the Dingjiazhai Formation indicates a possible Zisongian age. Possible Chuanshanian rocks appear in Tengchong and comprise black slate and pebbly graywake with dolomite and laminated dolomitic limestone in the top part. They were suspected to be equivalents of the glaciogenous diamictite in other areas of the Himalayan Region. The Yongde Formation rests on the Woniusi Formation with a disconformity. It may change into the purple bauxitic shale with such plant fossils as Lobatannularia sp. The brachiopod fossils from the Yongde Formation show a close affiliation to the peri-gondwana faunas. The Sazhipo Formation is dominated by dolomite and dolomitic limestone with an average thickness of 1,000m. Cryptospirifer aff. omeishanensis Huang was collected from the argillaceous limestone at the basal part, and the Shanita foraminifer fauna in the uppermost part in east of Baoshan. This formation ranges from the Xiangboan to the Lengwuan Stage [53].

Karamiran (VI) .17.......

A

S h u a n g h ~ j-

limestone Qomolangma Feng (I)

mudstone

sandstone

diamictite

andesite

~.;.~~

N ~f~

~'~5

Xainza (IV

_

_

; _ --

".~-.

. . 9 ye ga~9 F,,,... '" i

gagr,.f.

,% Yecheng Karakorum

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:.._.-_.-.

.>:

."4"--:..

,~V

.

, VI J

.

~

- - - X a i n z a ~ - - v ~ - . Toba~

[-- ]Continental ,

~~ Y o n ~ /J.~,

Figure 9. Fence diagram showing thickness and facies relationships of the Permian in Xizang. Sketch map showing the location of Permian outcrops in the Qinghai-Xizang Plateau. From Jin, 1985.

95

5. SUMMARY CHART (Figure 10) Figure 8 provides an overview of correlation between the Permian in major stratigraphic regions. The above summaries of regional Permian successions as well as the inter-regional correlation prove that the refined chronostratigraphic scheme for the Permian in China can be utilized over all China without particular difficulties. It also indicates that systematic, reliable data of isotopic dating and magnetostratigraphic sequences are urgently desirable. Historic development of stratigraphy reveals that improvement of Chinese and global stratigraphic schemes are mutually benefited. Outstanding reference sections can be established in China not only for the Lopingian Series, which has become an international standard, but also for the other parts of the Permian System. Among the latter, Chihsian stratigraphic sequence has shown a great potential of global stratotype.

Epoch

Stage

Superstratum Changhsingian

"~o

'

South China

Tarim

Leping

Kalpin

(Jiangxi)

(Xinjiang)

Tayeh Fm (T,)

'

Southern Qilian ~

NorthernChina '

(Qinghai)

Quaternary

!Changhsing Fmi ~ *

~_ !Wan~anli Wuchia- : ~ Shizishan Mb pingian .-~ Laoshan Mb

Tianjun

Taiyuan

Northern China borderland "

(Shanxi)

'

(XinJiang)

Xiahuancang Gr ~ Liujiagou Fm (T,) i (T,)

'

Urumqi "

Jiueaiyuan Fm

(T,)

j-

~

i

' ' ~ Zhongshigong : :

~

i

i

Fm

Sunjiagou F m :

Himalayas

Jisu

Tingri

(Neimongol)

(Xizang)

Jurassic

:Tulong Fm (T,

,

~ ~'~GG~u~

Fm i

~ Wutonggou Fm'

o~, Hajier Fm

Baga Fm

Z',

i Upper Quanzijia F m E . Shihhotse Fm i ~.. - ; : rGuanshan Mbl , , ~ 3 _ ]Hongyanchi F m I IL e n g w u a n ! '~ i i I ' i . i l i ..... ~f _ _ ~ Jisu F m ', I. . . . L __!._i.. ~-[ C a o t i e g o u F m - Mingshan Fm ~ ' i Lucaogou ~ Kuhfengiat~(ShizixingFm)i KalenderFm ! I~ ~ Lower ! Shihhotse Fm ! o,

;

9~

i

~ Xiangboant Hsiaokiang F m

>"

.~ -= L)

Luodianian~

I ~Leimengou Fm]

Baotege Fm Wulabo Fm

Chihsia Fm -i

.~

,Longlinian~

Otangkal F m

Shansi Fm

Kankarin F m

TaiyuanFm Substratum

~ U. Devonian I

Silurian h

L

Q u b u Fm t

*

+

Xilim]ao Fm

Caya Mb

]Shirenzigou Fm ~ i I"T~J ~]~ '% i A m u s h a n F m ~.~.~-i J.-.i-i ........................

~o, ~ ;=,iZadaerM1

Tashikula F m

i '

Zisongian Chuanshan Fm~

Qubuerga Fm

]Jingjingzigou Fmi

m

Baliqliq Fm

9.

. . . .

! Oertu Fm (Ct) r Benbatu Fm (C2) i i

i

Figure 10. Correlation chart of Permian stratigraphic sequences in China. The top lines of the column identify the major tectonostratigraphic regions, and the geographic names of type sequences for the provinces. Urmuqi and Jisu of the Northern China Boulder Region are type areas of Northern Xinjian and Beishan - Nei Mongol - Jilin regions respectively. Conformable relationships are indicated by straight lines, disconformity by dash lines, unconformities by saw-tooth margins, faulted boundaries by dotted lines, and facies boundaries by oblique straight lines. Hiatuses are marked by vertical shading, but with a question mark if the time interval of hiatuses have no precise biostratigraphic control [7].

96

The basal boundary of the Permian can be recognized in Permian sequence with Tethyan faunas in China. However, a major sequence boundary and also a bio-evolutionary turning point is located at the base of the Carboniferous Kasimovian Stage. There is no dramatic sea level change or faunal turnover at the beginning of the Permian, i.e. the early Asselian. Attempts to utilize this boundary level in field geology in China are currently discourage. The most prominent difficulties of inter-regional correlation in China are closely related to the long-standing problems of correlation between the Boreal, Gondwana and Pan-equatorial realms. The Permian in Northern Tianshan and the Junggar Basin and the Altay Shan are essentially composed of continental deposits. Permian biostratigraphic successions are closely related to those of the Urals, Russia but are distinct from those of North China and South China. The Lopingian marine strata in the Himalayas lack diagnostic fossils and thus, are hardly possible to correlate with Tethyan successions precisely.

6. A C K N O W L E D G E M E N T We acknowledge the financial supports from Chinese Academy of Sciences [Grant K2951B 1-409] and the National Natural Science Foundation of China [Grant 49672092].

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1. 2. 3. 4.

Richthofen,F.V., 1882. China. Berlin, 2(24): 1-792. Grabau, A.W., 1931. The Permian of Mongolia. Natur. Hist. Central Asia, 4(2): 1-422. Sheng J.Z., 1962. The Permian System in China. Science Press, Beijing. (in Chinese) Sheng J.Z., Jin Y.G., Rui L., Zhang L.X., Zheng S.G., Wang Y.J., Liao Z.T. and Zhao J.M. 1982. Correlation chart of the Permian in China with explanatory text. In: Stratigraphic Correlation chart in China with explanatory text, 153--170. Sei. Press, Beijing. 5. Jin Y.G., Shen S.Z., Zhu Z.L. and Wang W., 1996. The Selong Section, the candidate of the Global Stratotype Section and Point of the Permian-Triassic boundary. In: Yin H.F. (Editor), The Palaeozoic - Mesozoic Boundary, candidates of the Global Stratotype Section and Point of the Permian-Triassic boundary. Geological Publishing House, Beijing, pp. 127-137. 6. Sheng J.Z. and Jin Y.G., 1994. Correlation of Permian deposits in China. Nanjing University Press, Nanjing. Palaeoworld, 4: 14-113. 7. Jin Y.G., Wang X.D., Shang Q.H., Wang Y. and Sheng J.Z., 1999. Chronostratigraphic subdivisions and correlation of the Permian in China. Acta Geologiea Sinica 73 (2): 1 0 7 - 1 1 8 . 8. Huang T.K., 1932. The Permian formation of southern China. Geol. Mem. Surv. China, A (10):1-129. 9. Zhang Z.H., Wang Z.H. and Li C.Q., 1988. A Suggestion for Classification of Permian in South Guizhou. The People's Pub. House of Guizhou, Guiyang. (in Chinese, with English Abstr.) 10. Huang Z.X., Shi Y., Wei M.C., 1982. A new stratigraphic unit of the Permian-Longlinian Stage. Journ. Chengdu Col. Geol., 4: 63-73. (in Chinese, with English Abstr.) 11. Xiao W.M., Wang H.D., Zhang L.X. and Dong W.L., 1986. Early Permian stratigraphy and faunas in southern Guizhou. People's Publishing House of Guizhou, Guiyang. (in Chinese, with English Abstr.) 12. Zhu Z.L. and Zhang L.X., 1994. On the Chihsian Successions in South China. Nanjing University Press, Nanjing. Palaeoworld, 4:114-138. 13. Fan J.S., Qi J.W., Zhou T.M., Zhang X.L.. 1990. Permian Reef in Longlin, Guangxi. Geological Pubulishing House, Beijing. (in Chinese, with English Abstr.) 14. Zhao J.K., Zheng Z.G., 1977. The early Permian ammonoids from Zhejiang and Jiangxi. Acta Palaeontologica Sinica, 16(2): 217-252. (in Chinese)

97 15. Zhou Z.R., 1987. Early Permian Ammonite-Fauna from Southeastern Hunan. Papers Collection of post-graduates in Nanjing Institute of Geology and Palaeontology, Academia Sinica(1). Jiangsu Science and Technology Publishing House, Nanjing, pp. 343-398. (in Chinese, with English Abstr.) 16. Jin Y.G., Glenister, B.F., Kotlyar, C.K. and Sheng J.Z., 1994. An Operational Scheme of Permian Chronostratigraphy. Nanjing University Press, Nanjing. Palaeoworld, 4: 1-14. 17. Richthofen F.V., 1883. China. Berlin, 4(8): 160-208. 18. Kanmera K. and Nakazawa K., 1973. Permian-Triassic relationships and faunal changes in the Eastern Tethys. In: Logan and Hills (Editors), The Permian and Triassic Systems and their mutual boundary. Memoir, Canadian Society of Petroleum Geologists, 2, pp 100-120. 19. Furnish W.M. and Glenister B.F., 1970. Permian ammonoid Cyclolobus from the Salt Range, West Pakistan. In: Kummel B. and Teichert C. (Editors), Stratigraphic Boundary Problems, Permian and Triassic of West Pakistan. Spec. Publ. Univ. Kansas, 4, pp. 153-177. 20. Yang Z.Y., Cheng Y.Q. and Wang H.Z., 1986. The Geology of China. Clarendon Press.Oxford, Oxford, Monographs on Geology and Geophysics, 3. (in Chinese) 21. Zhou Z.R., 1987. First Discovery of Asselian Ammonoid Fauna in China. Acta Palaeontologica Sinica, 26(2): 130-148. (in Chinese, with English Abstr.) 22. Jin Yu-gan, Mei Shi-long & Zhu Zili, 1994. The Maokouan-Lopingian boundary sequences in South China. Palaeoworld, vol.4:119-132. 23. Jin Yugan, Mei Shilong, Wang Wei, Wang Xiangdong, Shen Shuzhong,Shang Qinghua, Chen zhongqiang, 1998. On the Lopingian Series of the Permian System. Palaeoworld, vol.9: 1-18. 24. Zhao J.K., Sheng J.Z., Yao Z.Q., Liang X.L., Chen C.C., Rui L., and Liao Z.T., 1981. The Changhsingian and Permian-Triassic Boundary in South China. Bull. Nanjing Inst. of Geol. and Palaeontologica, 2:1-95. (in Chinese, with English Abstr.) 25. Jin Y.G., Wardlaw, B.R., Glenister, B.F. and Kotlyar, G.V., 1997. Permian chronostratigraphic subdivisions. Episodes, 20(1): 10-15. 26. Wang Z.H., 1994. Early Permian conodonts from the Nashui Section, Luodian of Guizhou.. Nanjing University Press, Nanjing. Palaeoworld, 4: 203-225. 27. Jin Y.G., Shang Q.H., Hou J.P., Li L., Wang Y.J., Zhu Z.L., (in press). The stratigraphic lexion of China - the Permian Sysytem. Geological Publishing House, Beijing. (in Chinese). 28. Hou J.P. and Shen B.H., 1989. Late Permian Spora-pollen. In: Institute of Geology, Bureau of Geology and Mineral Resources of Xinjiang, and Institute of Geology, Chinese Academy of Geological Sciences eds., Research on Boundary between Permian and Triassic in Tianshan Mountain of China. Oceanography Press, Beijing. pp. 30-35. 29. Hou J.P. and Wang Z., 1990. Permian palynomorph assemblages of Northern Xinjiang. In: Institute of Geology, Bureau of Oil Prospect and Exploration of Xinjiang, and Institute of Geology, Chinese Academy of Geological Sciences eds. Permian to Tertiary strata and palynological assemblages in the North of Xinjiang. China Environmental Science Press. pp. 12-36. 30. Ross, C.A. and Ross, J.R.P., 1987. Late Paleozoic sea levels and depositional swquences. In: Ross, C.A. and Haman, D, (Editors), Timing and Depositional History of Eustatic Sequences: Constraints on Seismic Stratigraphy. Cushman Found Foraminiferal Res. Spec. Publ., 24, pp. 137-149. 31. Ross, C.A. and Ross, J.R.P., 1988. Late Paleozoic transgressive-regressive deposition. In: Wilgus, C.K., Hastings, B.S., Kendall, CGStC., Posamentier, H. and Ross, C.A. (Editors), Sea-level Changes: An Integrated Approach. Soc. Econ. Paleontal. Mineral Spec. Publ., 42, pp. 227-247. 32. Holser, W.T. and Magaritz, M., 1987. Events near the Permian-Triassic boundary. Mod Geol, 11:155180. 33. Leven, E.Y., Embry, A.F.; Beauchamp, B. and Glass, D.J., 1994. The mid-Early Permian regression and transgression of the Tethys. In:Pangea; global environments and resources. Canadian Society of Petroleum Geologists, 17:233-239. 34. Ding Y.J., Xia G.Y., Xu S.Y. and Zhao S.Y. 1992. The Carboniferous-Permian Boundary in China. Geological Publishing House, Beijing. (in Chinese, with English Abstr.)

98

35. Xia G.Y., Ding Y.J., Ding H., Zhang W.Z, Zhang Y., Zhao Z. and Yang F.Q., 1996. On the Carboniferous-Permian boundary stratotype in China. Geological Publishing House, Beijing. (in Chinese, with English Abstr.) 36. Chen H.H., Sun S., Li J.L., Heller, F. and Dobson, J., 1992. Permian-Triassic megnetostratigraphy of Wulong Area, Sichuan. Sciences in China, B(12): 1317-1324. (in Chinese, with English Abstr.) 37. Embleton, B.J.J., McElhinny, M.W., Ma X.H,, Zhang Z.K. and Li X.L., 1996. Perm-Triassic magnetostratigraphy in China: the type section near Taiyuan, Shanxi Province, North China. Geophys. J. Int., 126: 382-388. 38. Jin Y.G., Shang Q.H. and Cao C.Q., 1999. Callibration between Late Permian magneto- and biostratigraphic sequences of Tethyan areas. Sciences bulleting of Chian, 44(8): 800-806. 39. Bowring, S.A., Erwin, D.H., Jin Y.G., Martin, M.W., Davidek K. and Wang W., 1998. U/Pb Zircon Geochronology and Tempo of the End-Permian Mass Extinction. Science, 280(5366): 1039-1045. 40. Ishiga H., 1990. Palaeozoic Radiolarians. In: Ichikawa, K. et al.(Editors), Pre-Cretaceous Terranes of Japan. Nippon Insatsu, Osaka. pp. 285-295. 41. He X.L., Zhang Y.J., Zhu M.L., Zhang G.Y., Zhuan S.X., Zheng Y. and Zhu P., 1990. Research on the Late Paleozoic coal-beating stratigraphy and biota in Jungar, Nei Moungol [Inner Mongolia]. China Univ. Min. Techn. Press, Xuzhou. pp. 407 (in Chinese, with English Abstr.) 42. Institute of Geology, Bureau of Geology and Mineral Resources of Xinjiang, and Institute of Geology, Chinese Academy of Geological Sciences, 1987. The Carboniferous and Permian stratigraphy and biota in Kalpin Region, Xinjiang. Press of Oceanography, Beijing. pp.277. (in Chinese, with English Abstr.) 43. Zhou Z.Y. and Chen P.J. (eds), 1990. Biostratigraphy and geological evolution of Tarim. Science Press, Beijing. pp 366 (in Chinese). 44. Liang X.L., 1981. Early Permian cephalopods from Northwestern Gansu and Westem Nei Mongol. Acta Palaeontologica Sinica, 20(6): 485-500. (in Chinese, with English Abstr.) 45. Xia G.Y., 1982. Early Permian fusulinids from Maolipenhong Region in Nei Mongol Zishiqu. Bull. Of The Tianjing Inst. Of Geol. and Min. Res. CAGS., 5: 133-147. (in Chinese, with English Abstr.) 46. Ding Y.J., Xia G.Y., Duang C.H., Li W.G., Liu X.L. and Liang Z.F., 1985. Study on the Early Permian Stratigraphy and fauna in Zhesi District. Inner Mongol. Bulletin, Tianjin Institute of Geology & Mineral Resources, CAGS., 10:1-160. (in Chinese, with English Abstr.) 47. Liu F. and Waterhouse, J.B., 1985. Permian Strata and Brachiopods from Xiujimqinqi Region of Neimongol [Inner Mongolia] Autonomous Region, China. University of Queensland, Department of Geology, Papers, 11(2): 1-44. 48. Han J.X., 1981. General accounts on the fusulinid fossil zones of Early Permian age in the northern part of northeast China. Geol. Rev., 27(6):539-542. (in Chinese, with English Abstr.) 49. Sun H.Y., 1990. Permian fusulinids form the Dasuangou Formation in Yanbian County, Jilin. Acta Mictopalaeontologica Sinica, 7(3):257-264. (in Chinese, with English Abstr.) 50. Jin Y.G., 1985. Permian brachiopoda and palaeogeography of the Qinghai-Xizang [Tibet] Plateau. Palaeontologia Cathayana, 2:19-56. 51. Jin Y.G., Liang X.L. and Wen S.X., 1977. Additional material of animal fossils from the Permian deposits of the northem slope of Mount Jolmo Lungma. Scientia Geologica, 3: 236-249. 52. Norin, E., 1946. Geological Exploration in westem Tibet. In:Ibid. 29, III. Geology, 7: 1-214. 53. Wang X.D., Tetsuo Sugiyama and Katsumi Ueno, 1998. Carboniferous and Permian stratigraphy of the Baoshan Block, West Yunnan, Southwestern China. Permophiles, 32: 38-40.

Persian-Triassic Evolutionof Tethys and WesternCircum-Pacific H. Yin, J.M. Dickins, G.R. Shi and J. Tong(Editors) o 2000 ElsevierScienceB.V. All rightsreserved.

The Permian correlation

of Vietnam, Laos and Cambodia

99

and its interregional

Cu Tien PHAN Research Institute of Geology and Mineral Resources, Thanhxuan, Hanoi, Vietnam

The newly obtained research results allow correlation of the Permian of Indochina with those of China and other regions although with varying confidence. The clearest boundary in the local Permian stratigraphic scheme has been assigned to the base of the Dzhulfian formations. Some new data allow determination of a boundary at the base of the Permian and possibly the Upper Carboniferous - Permian. In Indochina, the fusulinids are of special significance because of their common occurrence and rapid evolution; however the contribution of data from other groups of organisms is and will remain of great significance. Lower and Upper Permian could be retained as series of the Permian according to their general usage and subseries can be recognized in the Upper Permian of Indochina Peninsula and adjacent territories of Southeast Asia and Eastern Asia.

1. I N T R O D U C T I O N This paper will not deal with the whole Indochina Peninsula. It is concerned mainly with Cambodia, Laos and Vietnam, the Indochina countries; however the Permian formation of the three countries will be correlated with those of Thailand, Malaysia of Indochina Peninsula and South China, Japan as well. The first description of the Permian formation of Indochina were presented in the beginning of this century. These are Productus Quartz Sandstone, Fusulinid-bearing Limestone and others [1, 2, 3]. Relating to the tectonostratigraphic interpretation, Fromaget considered the Permian formations of Indochina as parts of Anthracolite Limestone or Indosinias Terrigene [4]. In the view of stratigraphic correlations. Saurin classified the Permian formations into Artinskian, Kungurian, Kazanian, or some fusulinid horizons [5, 6]. Since 1954, in the geological publications, the Permian formations of Vietnam and its relationship with the Carboniferous were described as a monotonous sequence belonging to the "tectonic leveling" of the territories [7]. However on the basis of newly collected data, Permian formations of Vietnam in particular and Indochina Peninsula in general were recognized to be complicated with various composition and abundant mineral resources[8-10]. In the geological development of Vietnam and adjacent territories, the Permian geological events accompanying the change of structural framework, palaeogeography and volcanic

100 activities have been identified.

2. P E R M I A N

VOLCANO

- SEDIMENTARY

FORMATIONS

In Indochina, the following stratigraphic regions have been classified in the geological map of Cambodia, Laos and Vietnam: Vietbac, West Bacbo, Truongson, Kontum Savannakhet, Dalat Stungtreng and Northwest Laos [9]. These regions are separated from the West Thailand region by the Nan Suture (Fig. 1). In the Vietbac, the lower part of Permian is characterized by monotonous, black, grey limestone corresponding to the upper part of the Bacson Formation of Carboniferous Permian. The definition of Permian is mainly based on Schwagerina or Robustoschwagerina, Misellina, Cancellina, Neoschwagerina, Lepidolina - Yabeina horizons of Asselian - Midian [11-15]. Here, the Dongdang Formation of D z h u l f i a n - Darashamian age overlies unconformably on the eroded surface of the above mentioned limestones and comprised basal bauxite beds, shale, chert and limestone. The limestones contain Codonofusiella aff. paradoxa Dunbar et Skinner, Dunbarella sp. in the lower part and Palaeofusulina prisca Deprat, Colaniella parva (Col.), Reichelina pulchra M. Maclay, Neoendothyra eostaffelloidea Liem and Leptodus sp., in the upper part. The Lower Triassic sandstone, silstone containing Claraia, Glyptophiceras overlies the above - mentioned formation with an either conformity or a disconformity [16]. In some places such as Baichay, the Upper Permian comprise quartzite, shale, chert and coal seams. The collected fossils are Meekella cf. ufensis Tchernyshev, Lyttonia sp., Productus gratiosus Waagen, Martiniopsis aff. orientalis Tchernyshev, Spiriferina cambodgiensis Mansuy, Pseudomonotis cf. garforthensis King, Pseudophillipsia cf. acumulata Mansuy,... [1 ]. In the West Bacbo region, the Permian sedimentary sequence is presented mainly by the Lower Permian and may be Upper Carboniferous as well (Table 1). In the southwestern periphery of the region, at Thanhhoa area, the Lower Permian limestone continuous from the Upper Carboniferous limestone; however the Upper Permian mafic volcanics of the Camthuy Formation overlies unconformably the older formations. The formation is composed of volcanics belonging to the picrite - basalt association, 700 - 800m thick. Overlying the mafic volcanics, there are shale, chert, coal shale, coal seams, limonite, hematite beds in places and limestone of the Yenduyet Formation. The thickness of the coal seam varies, from 20 - 30 cm to 6 m. Limonite, hematite beds have the thickness of 3 m, Fe203 varies from 23 - 37% to 62% in places, A1203 22 - 23%, SiO 2 12-17%. The collected fossils in shales comprises Leptodus sp. (cf. L. nobilis Waagen), Squamularia sp., Schellwienella sp., Chonetes sp., Actinodesma sp., Spiriferella sp., Neophricodothyris cf. asiatica Chao and Aviculopecten sp., Oldhamina sp., Marginifera cf. lopingensis (Kayser), Andersonoceras sp., Pseudotirolites sp., Gigantopteris sp., Pterophyllum sp. [18] and Chonitipustula sp., Dielasma sp., Productus (Alexenia ?) sp., Chonetes sp., Spirifer sp., [7]. Similar sections also crop out in Sonla, Laichau along the eastern periphery of the Songma anticlinorium, the collected fossils comprise Peltichia kwangtungensis (Zhan), Acosarina minuta (Abich), Rhipidomella hessensis King, Schuchertella cf. cooperi Grant, Derbyia sp., Waagenites soochowensis (Chao), Spinomarginifera chenyaoyanensis Huang, Marginifera gen. et sp. indet. [17]. The relationship between the Upper Permian and Lower Triassic is conformity or disconformity.

101

4-,'"

%%

!

"~

! Ph~

SONLA BACBO

Sl

NORTHWEST

,

LAOS

tx x

Bacson

HOABINH

Ikhay

Luongphabang

CHINA

!

VIETBAC

/

/

Muongxen ~ ~'%,.,,~,% % % TRU~N~G

[ / ,I,..-, .,-",_VIENTIANE '~%%,.,,#$

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SON..,.

X%

i

\

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x

x\ SAVA x NAKHET

THAILAND

! I ! I

X

/ ,O.TUM \

.1 Ratburi BANG K

/

/

/

"~

~

\

\

Sis

I

Pursat

4.~ i~.../" ..,, /

DALATf

X.,j Tathiet

L/F------150 I

75 I

0 I

75 I

150 I

225 I

300 Ikm

Figure 1. Stratigraphic Regions of Cambodia, Laos, Vietnam (main land) and adjacent regions. VIETBAC

Stratigraphic region name

/

i

Deep - seated fault

102 In the Da river valley, mafic volcanics have great thickness, various composition and are closely related to ultramafic and mafic intrusions. It seams possible to define 3 magmatic associations from the lower part to the upper part of the section. These are picrite basalt andesite association closely related to the picrite diabase association; basalt komatiite and trachydacite, trachyandesite basalt association. The above association underlie siltstone, shale, marl, sandstone of the Lower Triassic (Olenekian). In the picrite basalt of the picrite basalt andesite association, the percentage of basalt reaches 70 - 80%. According to the petrochemical characteristics, these rocks are rather highly alkaline and high in TiO2. Total alkaline reaches 3% in subultramafic and 3.6% in mafic intrusion; TiO2:1.8 and 2.2 respectively; K20/Na20: 0.38; A1203:8.4 - 24 and FeO: 8.4 -

14%.

Pertaining to the picrite diabase association, there exist dike, veins and subvolcanic bodies of peridotite, picrite diabase and gabbro ophyte belonging to the ultramafic, ultramafic - mafic and mafic groups. The ultramafic group is characterized by low alkalinity. Na20 + K20 < 1%; TiO2 < 1; A1203:5.17 - 5.56; relatively high MgO: 3.0 - 4.5%; Na is predominant. Basalt komatiite association is recently defined in the center of Da river valley and composed of komatiitic peridotite (20 - 40% MgO), komatiitic basalt (12 - 20% MgO), olivine bearing basalt rich MgO and leucocratic basalt (< 8% MgO). Petrochemically, the association is characterized by TiO2:0.12 - 0.19; CaO/A1203:0.8 - 1.1; CaO/TiO2:14.4 - 21.5 and A1202/TiO2:18.3 - 23.4%. The trachydacite-trachyandesite-basaltoid association crops out mainly in the eastern periphery of the region and seems to be of Permian and Permian-Triassic age. This association is characterized by high alkaline, alkaline and subalkaline rocks, SiO2:49.4 - 67.5; TiO2:0.7 - 3.7; A1203: 14; MgO: 0.4 - 6.3; CaO: 1.1 - 8.3%; total alkaline > 4%, among them K > Na in trachyandesite. The contacts between the volcanic formations and other ones are mainly tectonic. The intercalation of sedimentary and volcanic rocks can be seen in some places such as the Hoabinh hydroelectric dam site. In ascending order this section comprises of: 1) basaltic porphyrit, 20 m thick; 2) limestone, marl, 20 m thick; 3) carbonate siltstone containing badly preserved brachiopods, 10 m thick; 4) limestone containing Triticites (?) sp., Pseudofusulina sp., Misellina ovalis Deprat, 20 m thick; 5) basalt, tuffs, 17m thick; 6) sandstone, siltstone, marl containing Ditomopyge sp., Aulacorhyncus protechwensis Grabau et Tien,

Propinacoceras aff. aktubense Rhyzhensev .... 15m thick; 7) limestone containing Misellina ovalis (Deprat), Neofusulina sp., Pseudofusulina sp., 30 m thick [8]. In the Truongson region, Permian and Carboniferous limestones crop out in continuous sections at Quydat, Muongxen of Vietnam and Nonghet, Khammoun, Vangvieng of Laos. Permian limestone contain abundant fusulinids corresponding to the Schwagerina, Robustoschwagerina, Misellina, Cancellina and Neoschwagerina horizons. Uppermost part of the Permian have been observed in places. At Khegiua area, limestones contain Codonofusulina nana Erk, Neoendothyra eostaffelloidea Liem, Palaeofusulina (?) sp., Reicheline (?) sp. [13], and at Camlo area, shales contain Leptodus nobilis (Waagen), Chonetes subtrophomenoides Huang and Meekella kweichowensis Huang [18]. The relationship between the above limestones and older formations is not defined yet. The Permian volcano sedimentary formation of this region is restricted to the narrow band along the fault in Alin area of Vietnam and enlarged in Khangkhay area of Laos. Along the

103 road N017 from Phonsavan to Khangkhay, the formation is composed of grey shale, marl containing Plicatifera sp., Schuchertella sp., Anarsalites sp. of the lower part; red coloured carbonate, siltstones, sandstones of upper part [9]. In the Dalat Stungtreng region, the Daklin Formation of the Upper Carboniferous-Permian crops out in the same name in Vietnam and comprises shale, chert, andesite, basaltic andesite in the lower part; andesite, tufts, sandstone in the middle part; and andesite, basaltic andesite, dacite, rhyolite, marl, limestone in the upper part. The collected fossils are badly preserved bryozoans, crinoids, brachiopods in shale and Sschwagerina sp., Pseudofusulina sp., Verbeekina sp. in the limestone. The volcano-terrigenous formations distributed in the Stungtreng, Preah Vihear, Siemreap of Cambodia can be correlated with those in the Daklin area. The intercalations of volcanic rocks and limestone were observed in the right band of Mekong River, North of Stungtreng, in Chhep and Stungtreng [19, 20]. Permian limestones crop out in Hatien of Vietnam, Campot, Phnomxa and Battambang of Cambodia. The Hatien Formation in Vietnam is characterized by limestones containing Verbeekina verbeeki Genitz, Neoschwagerina margaritae Deprat, Codonofusiella sp., Parafusulina sp., Nankinella sp. and gastropods, rugose corals and crinoids [9, 16]. In Phnomxa of Cambonia, the Permian formation is composed of: 1) basal conglomerate containing fragments of quartzite, sandstone, rhyolite; 2) oolitic limestone; 3) fossiliferous marl, limestone; 4) siliceous limestone containing sponge and radiolarians; 5) massive limestone [ 19]. According to Dottin and Langle [20], the Permian stratigraphic scheme of Cambodia is composed of: 1) limestone containing Yangchienia and Cancellina of Artinskian age; 2) limestone containing Praesumatrina dunbari in Phnom Svai and Verbeekina verbeeki, Neoschwagerina douvillei in Battambang of Kungurian age; 3) limestone containing Yabeina and Lepidolina of Kazanian age; 4) limestone containing Brachiopoda in Battambang of Upper Kazanian and 5) limestones schists in Svaycheck of Tartarian age. The uppermost part of Permian crops out in Tathiet, at the Cambodia-Vietnam border and comprises siltstone, sandstone, shale containing Streptorhyncus cf. perlargonatus (Schlotheim), Uncinunellina sp. (aff. U. timorensis Beyrich), Giriypecten sp., Palaeolima sp. in the lower part and limestone containing Palaeofusulina prisca (Deprat), Colaniella parva (Col.), Reichelina pulchra M. Maclay, Neoendothyra dondangensis Liem in the upper part. The above-mentioned sediments conformably underlie sandstone, siltstone containing Claraia, Otoceras (Motococeras) of the Triassic [ 16, 21 ]. Except the carbonate terrigenous formations, andesite, rhyolite, tufts, aglomerate in Honchong of Vietnam and in Campot of Cambodia were classified into Permian-Triassic in the correlation with those in West Thailand and Malaysia [22, 23]. In the Northwest Laos region, the Songda Formation at the Muongte area of Vietnam is made of coglomerate, sandstone, shale, chert, andesite, rhyolite and limestone containing Pseudofusulina sp., Parafusulina ex gr. japonica (Gumb.), Misellina ex gr. ovalis (Deprat) and Chonetes sp. [7, 9]. In the territory of Laos, the Permian formations comprise also sandstone, shale, tufts and limestone containing Orthoceras sp., Griffitides sp., Productus aagardi at Sayabuli and Pseudofusulina japonica, P. gigantea at Nambac valley [5]. In this region, Fromaget [4] described a coal-bearing formation of Permian age at Soppong. Here, sandstone, shale and coal-shale contain Gigantopteris nicotinaefolia, Cordaites cf. Principalis and Schizoneura gondwanensis. The relationship between the Permian volcanosedimentary, carbonate and coal-bearing formations has not been defined yet.

Table 1 9Permian Stratigraphic Correlation of C a m b o d i a , Laos and V i e t n a m Dalat

West Bacbo

Truongson

- Stungtreng

|

Hatien, Battambang

i

Tathiet

West Hue, Xiengkhoang

Daklin, Stungtreng

Quydat, Nonghet

Sonla, Thanhhoa

Vietbac Vanyen, Hoabinh

Lower Triassic

Lower Triassic:

Otoceras

Claraia and

Lower Triassic 9

Costatoria and

Clarata, Lingula

(Metotoceras) and

Lytophiceras ....

Eumorphotis ....

and Glyptophiceras ....

....................... Yenduvet Formation

Lobatannularia,

Dongdang Formation

Palaeofusulina and

Pecopteris,

Palaeofusulina and

CodonofusieUa Horizons

Gigantopteris ....

Codonofusiella

Leptodus Chonetes and Gigantopteris, ...

Volcanics

Claraia .... i -9- - . - - ~ - P e r m i a n - Triassic i Volcanics

...................

Permian - Triassic

Camlo s h a l e s

Volcanics

Leptodus, Chonetes

9

and Dyctyoclostus .... .....................

Tathiet Formation

..................

Palaeofusulina Horizon

Viennam Formation

Horizons Leptodus

Volcanics

Upper pa~ of

!

Hatien (Battambang)

A l i n (Khangldaay)

Formation:

Lepidolina and

Daklin Formation

Neoschwagerina

Verbeekina

Horizons

Pseudofusulina and Schwagerina (?) .... Volcanics

Muonglong

Upper part of

(Nonghet) Damai Formation :

Bandiet Formation

Bacson Formation :

Formation 9

Formation:

Neoschwagerina,

MiseIlina, and

Neoschwagerina,

Plicatifera, Anatsalites

Neoschwagerina,

Misellina,

Robustoschwagerina

Misellina,

and Schuchertella ....

Cancellina, Misellina, Robustoschwagerina and

Horizons

Robustoschwagerina

Volcanics

Robustoschwagerina and

Propinacoceras

and Schwagerina Horizons

Schwagerina Horizons

Schwagerina Horizons

Schwagerina ,,--"""

?

Upper part of

Neoschwagerina,

"rtticttes Horizon

...'"""" Horizons

Titicites Horizon

Triticites Horizon

105 3. S T R A T I G R A P H I C C O R R E L A T I O N OF PERMIAN FORMATIONS. The newly obtained data in Cambodia, Laos and Vietnam allow a correlation of Permian formations of the three countries with those of South China and adjacent regions although with different confidence. In the Vietbac region, the boundary between the Neoschwagerina-bearing limestones of the Bacson Formation can be correlated with the base of the Wuchiaping Formation of the Lopingian Series or the top of the Maokou Formation of the Yangsingian Series [24]. The latter have been correlated with the Guadalupian Series [25]. In the West Bacbo, the mafic volcanics of the Camthuy Formation is easily correlated with the Omeishan Basalt Formation in Yunnan and Guizhou of China although their origins may be complicated. The Yenduyet Formation may correspond to two formations of Lopingian Series and the volcanics of Bandiet Formation are also correlatable with those of the Maokou Formation in the above-mentioned provinces of China (Table 2). For long, in China the lower boundary of the Permian has been placed at the base of Chihsia Formation containing Misellina claudiae which was originally defined in the Nanjing area where the formation lies with a hiatus on older beds [24]. This practice has also been followed in Vietnam [ 14, 15]. More recently practice has tended to look for a Lower Permian basal boundary equivalent to the base of the Asselian as used in the Ural area and many other parts of the world. The traditional subdivision is thus rather in a state of flux. As discussed below a return to the orginal definition of the Chihsia has a potential for a clearer correlation with Japan and the two subdivisions of the Upper Permian (for a twofold Permian System), the Yanghsingian and Lopingian [ 10]. The geological events at the top of the Bacson Formation in the Northeast and West Bacbo of Vietnam or the Maokou Formation in the Yunnan and Guizhou of China seem to be unclear in the Truongson and Dalat Stungtreng regions. Fromaget [4] recognized the Moscovian geological event in Indochina. However it is unconfirmed by recent investigations. Some newly obtained data in Vietnam and in Laos allow determination of boundary at the base of the Khangkhay, Daklin and possibly Hatien Formation. May be, this boundary coincided with the boundary in Upper Carboniferous-Permian in the regional column of Khorat Plateau [26, 27]. The Tathiet Formation at the uppermost part of the Saigon river can also be correlated with the limestones in the Doi Pha Pleung, Amphoe Ngao and Changwat Lampang areas and in some other places [28]. The Permian - Triassic Honchong Formation may also be equated with the volcanic sequences of the same age in Thailand and Malaysia [20, 22]. Considerable progress has recently been made in Central and Western Thailand. In Central Thailand, strong folding and orogenic activity with flysh formation has been described in the Kubergandian- Midian [29]. In Western Thailand, an unconformity seems to present at the base of the Permian or Upper Carboniferous sequences. However the detailed descriptions and age remain unclear [30, 31]. In most recent publications [32, 33], a local subdivision of the Permian has been used, in which the Lower Permian remains poorly known, the rest being composed of Kubergandian and Murgabian belonging to Middle Permian and the Midian together with the Dzhulfian and presumably the Dorashamian and equivalents belonging to Upper Permian. Whether the Midian-Dzhulfian event is present in Thailand as found in Vietnam, China and Japan is thus unclear. The Middle Permian, however, is apparently represented in the beginning of the orogenic event in the Kubergandian, and Dawson [32, 33]

Table 2 9Stratigraphie Correlation of Permian in Vietnam and Adjacent Regions Traditional standard Southern

Proposed classifi cation of SPS

Urals

Changhsinglan

Armenia Iran, Pamir

South China Changhsingian Palaeofusuhna smensls P. minima Gallowaynella meitwnsis Wuchiapin~oian Nankinella simplex Codonofuswlla kwangstensts

Darashamian

-~o Wuchiapingmn Tartarian

i

Wordian

Ufimian

Roadian

Kungurian

Kungurian

.~

Artinskian

Murgabian

Kubergandianian

Blorian

Yakhtanshian

Sakmarian

Sakmarian

Sakmarian

Asselian

Asselian

Asselian

[251

~o G

Maehaman

Lepidolina kumaensis Lepidohna kumaensts

i

Palae@r

Palaeofusulina Condonofuswlla

slnensIs

Gallowaynella Colaniella Codonofuslella

Jin et al (1997)

[251

Kotlyar, 1987 Leven et al, 1993 in Jin et al., (1994)

[241

=

~:~ >-

y.

Lengwuan Metadoliolina multtvoluta Yabema gubleri Kuhfengian Neoschwagerma margaritae N. craticulifera

Midian

._~

Chuvashov, 1993 in Jin et al., 1997

Nabekoshian Palaeofusulina sp.

Vietnam

Thailand

E

Capitanian

Kazanian

Artinskian

Dzhulfian

South Kitakami, Japan

=

Iwaizakian Lepidolina multiseptate Kattizawan Colantella douvillei Monodwxolina matsubaishi Misellina claudine

Xiangboan N. simplex Cancelhna ne oschwagerinoides Luodianian Mtsellina claudiae Brevaxina dyhrenfurthi Longlinian Panurina darvastca Darvasites ordinatus Zisonglan Robustoschwagerina schwellwiem R.ziyunensis Sphaeroschwagerina moellert Svulgaris Pseudoschwagerina muongthensts

9

Ne oschwagerma Verbeekina Parafusulina

Kabayama

N 9 9

E

Pseudofusulina fusiformis p. vulgaris (s. l) Kuwaguchi Rugosofusilina alpina Zelha nunosel

Minato et al., 1965 in Dickins (1990) [35] Sheng & Jin (1994) [24]

Lepidolina Neoschwagerina Cancellina

Pseudofusulina slameilsls

Pse udoschwagerma talensis Robustoschwagerina Triticites suzukit

R.Invagat - Helmck (1994) [281

Misellina Robustoschwagerina Pseeudofusulina Pseudoschwagerina Schwagerina

This paper

107

for example, suggest an unconformity might be present at this level. In the Malayan Peninsula, the Chuping Limestone is generally regarded as equivalent to the Rat Buri Limestone. It is structural relationships, however, are not at all clear. Metcalfe [34] has argued that the collision occurs at the Permian- Triassic boundary inferring a major period of tectonism at this time because of a lower order of folding associated with the Bentong - Raub Suture in the Triassic compared with the Permian. Whether this is a local or general future from the existing evidence is an open question and why the folding in Central Thailand should not also represent a collision requires an answer. A threefold subdivision of the Permian is used in Japan: Lower, Middle and Upper Permian [35]. The lower Permian corresponds to the Lower Permian of the Russian twofold subdivision and the Lower Middle and Upper Permian correspond to the Upper one of the Russian sequence. Further the Upper Permian of Japan corresponds to the traditional Upper Permian of China. The Kanokura Series making up the Middle Permian has Misellina claudiae at its base according to Ozawa [36] and has marked discordance and magmaticvolcanic and tectonic activity. Reliable correlation is available with China with the boundary of the Konokura and Toyoma Series (the Upper Permian) corresponding to the Maokou Wuchiaping boundary. As in China (and Vietnam) in Japan this boundary is associated with complex volcanic and tectonic activities.

CONCLUSION The newly collected data from Cambodia, Laos and Vietnam allow a varying degree of correlation of the Permian of Indochina with those of adjacent areas. The review suggests that the most suitable scale for the Permian of this region is a threefold one that can be fitted in to the framework of the traditional twofold Permian System. This scale reflects data from many groups of organisms especially the fusulinids. In this scheme, the possibility of retaining the Chihsia according to its original definition would allow using the names Yangsingian and Lopingian as Subseries names of the Upper Permian. Retention of Bolorian in the Lower Permian and Midian in the lower of the two Upper Permian Subseries is also recommended. For this, a study and comparison of critical fusulinids such as Misellina claudiae could prove to be of considerable significance.

ACKNOWLEDGEMENTS The author is very thankful to the Departements of Geology and Mines of Cambodia, Laos and Vietnam for kind support for geological surveys. Warms thanks are extended to Dr. J.Dickins, Prof. Yin Hongfu and Dr. Guang R.Shi for very valuable discussions.

REFERENCES

1. 2.

M.Colani, Sur quelques fossiles Ouralo - Permien de Hongay. Bull. Serv. Geol. lndoch., Vol. VI, fasc. 5, Hanoi (1919), 27pp. J. Deprat, Etude des fusulinid6s de Chine et d'Indochine et clasification des calcaires /l fusulines (2e memoire). Les fusulinid6s des calcaires Carboniferiens et Permiens du Tonkin, du Laos et du Nord

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Annam. Mere. Serv. Geol. lndoch, Vol II, fasc. 1, Hanoi (1913), 74 pp. 3.

5. 6. 7. 8. 9. 10.

11. 12. 13. 14.

H. Mansuy, Faunes des calcaires ~. Productus de i'Indochine, 1e serie. Mere. Serv. Geol. Indoch, Vol II, fasc. 4, Hanoi (1913), 137 pp. J. Fromaget, L'Indochine frangaise, sa structure geologique, ses roches, ses mines et leur relation possible avec la tectonique. Bull. Serv. Geol. Indoch, Vol XXVI, fasc. 2, Hanoi (1941), 140 pp. E. Saurin, Les Fusulinides des calcaires de Kylua, Langson. Bull. Serv. Geol. Indoch, Vol XXIV, fasc. 5, Hanoi (1950), 36 pp. E. Saurin, Indochine. In Lexique stratigraphique Internationale. Centre Nationale de la Rech. Scient., Paris (1956), 140 pp. A.E. Dovjikov (ed) et al, Geology of Vietnam. Explanatory note to the geological map of North Vietnam, Hanoi (1965) in Vietnamese, 584 pp. Phan Cu Tien, Upper Permian- Lower Triassic sediments in Northwest Vietnam. Nhung van de dia chat TBVN, Hanoi (1977), in Vietnamese, 109 - 151. Phan Cu Tien (ed) et al, Geology of Cambodia, Laos and Vietnam. Explanatory note to the geological map of Cambodia, Laos and Vietnam, 2 nd edition, Hanoi (1991), 156 pp. Phan Cu Tien and J. Dickins, Subdivision and correlation of Permian Stratigraphy of Vietnam and adjacent regions of Southeast Asia anf Eastern Asia. Journ. Geol. Series B, Vol. 5-6, Hanoi (1994), 3747. Nguyen Van Liem, On the stratigraphic subdivision of the Upper Paleozoic in the 1:500.000 geological map of North Vietnam. Dia chat, Vol. 74, Hanoi (1967), in Vietnamese, 6 - 8. Nguyen Van Liem, The Bacson Series of Vietnam. Stratigraphic correlation between sedimentary basins of the ESCAP region. Min. Res. Dev. Series 45, United Nation, New York (1979), 62 pp. Le Hung, New data on the biostratigraphy of Upper Paleozoic in North Vietnam. Tuyen tap Khoa hoc ky thuat, Hanoi (1975), in Vietnamese, 142- 183. Le Hung, Permian stratigraphy in Vietnam and its correlation with equivalent formation in Indochina.

Proc. 1st Conf. Geol. Indoch., Hanoi (1986), 89-100. 15. Tran Duc Luong and Nguyen Xuan Bao (eds) et al, Geological map of Vietnam, 1:500 000 scale, Hanoi (1988). 16. Vu Khuc and Bui Phu My (eds) et al, Geology of Vietnam. Vol. 1. Stratigraphy, Hanoi (1988), in Vietnamese, 174 - 214. 17. G. Shi and S. Shen. A Changhsingian (Late Permian) brachiopod fauna from Sonla, Northwest Vietnam. Journal of Asian Earth Sciences, Vol. 16, n o 5-6, (1998) 501 - 511. 18. Tran Thi Chi Thuan, Les brachiopodes permiens de Camlo. Ann. Fac. Scient., Univ. Saigon (1962), 485498. 19. J. Gubber, Etudes geologiques darts le Cambodge Occidental. Bull. Serv. Geol. lndoch., Vol XXII, fasc. 2, Hanoi (1935), 176 pp. 20. BRGM, Cartes geologiques de reconnaissance du Cambodge ~, l'echelle 1:200.000 et les notices explicatives. Paris (1968-1972). 21. H. Fontaine et al, The Permian of Southeast Asia. CCOP. Tech. Bull., Vol 18 (1986), 171 pp. 22. B.K. Tan and T.T. Khoo, Review of the development in the Geology and Mineral resources of Malaysia and Singapore. Proc. 3 rd Reg. Conf. Geo SEA, Bangkok (1978), 655-671. 23. S. Bunopas, The regional stratigraphy, paleogeographic and tectonic events of Thailand and continental Southeast Asia. Stratigraphic correlation of Southeast Asia, Bangkok, (1994), 2-14. 24. Y, Jin, J. Utting and B. Wardlaw (eds) et al, Permian Stratigraphy, Environment and Resources. Vol.l: Paleontology & Stratigraphy, Nanjing (1994), 262pp. 25. Y. Jin et al, Permian chronostratigraphic subdivision. Episodes, Vol. 20, n~ (1997), 10-15. 26. C. Mouret, Geological history of Northeastern Thailand since the Carboniferous relation with Indochina and Carboniferous- Early Cenozoic evolution model. Stratigraphic correlation of Southeast Asia, Bangkok (1994), 132-158. 27. O. Chinoroje and M. Cole, Permian carbonates in the Dao Ruang #1 Exploration Well- Implications for Petroleum Potential, Northeast Thailand. Intern. Conf. Geology, Geotechnology and Mineral Resources of Indochina, Khon Kaen (1995), 563 - 576.

109

28. 29. 30. 31. 32. 33. 34. 35. 36.

R. Invagat-Helmck, Paleozoic paleontological evidence of Thailand. Stratigraphic correlation of Southeast Asia, Bangkok (1994), 43 - 54. D. Helmck and H. Lindenberg, New data on the Indosinian orogeny from Central Thailand. Geol. Rdsch. Vol. 72, n ~ 1 (317 - 328). S. Chantaramee, Tectonic synthesis of the Lansang area and discussion of regional tectonic evolution. Proc. Reg. Conf. Geo SEA, Bangkok (1978), 177 - 186. T. Thanasuthipitak, Geology of Uttaradit area and its implication on tectonic history of Thailand. Proc. Reg. Conf. Geo SEA, Bangkok (1978), 187 - 197. O. Dawson, Fusuline foraminiferal biostratigaphy and carbonate facies of the Permian Ratburi limestone, Saraburi, Central Thailand. Jour. Micropalaeontology, Vol.2 (1993), 9-3. O. Dawson et al., Permian foraminifera from Northeast and Penisular Thailand. Stratigraphic correlation of Southeast Asia, Bangkok (1994), 323 - 332. I. Metcalfe, Gondwana dispersion and Asia accretion. Journ. Geol. Series B, Vol. 5 - 6, Hanoi (223 267). J. Dickins, Permian of Japan and its significance for world understanding. Proc. Shallow Tethys 3, Sendal (1990), 343 - 353. T. Ozawa et al., Biostratigraphic zonation of Late Carboniferous to Early Permian sequence of the Akiyoshi Limestone Group, Japan and its correlation with reference section in the Tethys region. Proc. Shallow Tethys 3, Sendal (1990), 327 - 341.

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Persian-Triassic Evolutionof Tethys and WesternCircum-Pacific H. Yin, J.M. Dickins, G.R. Shi and J. Tong (Editors) 92000 ElsevierScienceB.V. All rights reserved.

111

The m a r i n e P e r m i a n of N e w Z e a l a n d H. J. CAMPBELL a alnstitute of Geological and Nuclear Sciences Ltd., PO Box 31-312, Lower Hutt, New Zealand. This paper summarises what is known of the marine Permian rocks of New Zealand in terms of terranes, their known faunal content, biostratigraphic age control and correlations. Fossiliferous sedimentary rocks of Permian age are comparatively restricted in distribution in New Zealand but are recognised within six tectonostratigraphic units or terranes (Fig.l). Well-exposed, readily mappable and stratigraphically coherent fossiliferous successions are confined to two of these terranes, the Brook Street and Dun Mountain-Maitai Terranes. Strata within these two terranes are host to all documented New Zealand Permian biostratigraphic units [1, 2]. Permian sequences in all terranes are exclusively marine or marginal marine. 1. T E C T O N O S T R A T I G R A P H I C F R A M E W O R K OF N E W Z E A L A N D Two major tectonostratigraphic divisions are recognised in New Zealand (Fig. 2). These are the Western Province and the Eastern Province, and each consists of a number of terranes [3, 4]. All Eastern Province terranes were metamorphosed during Late Jurassic Early Cretaceous time. Western Province terranes were variably metamorphosed in the Paleozoic and again in the Mesozoic. Correlation between Eastern Province and Western Province metamorphic events, if any, is unclear.

1.1. Western Province The Western Province [5], bordering the Tasman Sea, is essentially a fragment of Australian continental foreland comprising distinct Paleozoic terranes (Buller, Takaka). This 'province' constitutes the dispersed New Zealand segment of autochthonous Gondwanaland. The Western Province is notable because it includes the oldest known rocks in New Zealand (Middle Cambrian) and it is also host to extensive plutonic rocks of Cretaceous age that are conspicuously absent within the Eastern Province [6]. A fragmentary record of a Gondwanaland cover sequence with strong eastern Australian affinities is preserved within the Western Province and this includes Devonian, Permian and Triassic successions and Jurassic dolerite of Ferrar Magmatic Province affinity [7, 8]. Curiously, there is no fossil evidence of a Carboniferous sedimentary record.

112

170 ~ E

175 ~ E

N

WESTERNPROVINCE undifferentiated

35 ~ S

35 ~ S

MEDIANTECTONICZONE Median Batholith

oQ

EASTERNPROVINCE CentralArcTerranes

MEDIAN TECTONIC ZONE

1. BrookStreet 2. Murihiku 3. Dun Mountain- Maitai

TorlesseSuperterrane

WESTERN PROVINCE/

4. Caples 5. Waipapa 6. Rakaia 7. Esk HeadMelange 8. Pahau 9. Waioeka

40~ S

EASTERN PROVINCE

40 ~ S

Australian Plate Pacific Plate

Torlesse Superterrane

45"S

45~ S

EASTERNPROVINCE --

2

CentralArc Terranes

MEDIAN TECTONIC ZONE (MTZ)

0 I

.,,

165 ~' E I

I

170 ~ E I

175,-~ E I

1 O0 I Kilometres

200 I

180oE I

I

Figure 1. Simplified basement map of New Zealand showing distribution of the major tectonostratigraphic entities: provinces, terrane assemblages, terranes and their fault boundaries. Key components of the modem tectonic setting are also shown.

GEOLOGICAL

TIME

Series

Stage

TRIASSIC

Olher

Relevant Regional Stage Correlation

Changhsingian Lopingian Wuchiapingian

EASTERN PROVINCE

NEW ZEALAND BIOSTRATIGRAPHY

Stages

Bmchiopod Zones

Cenlral Arc Terranes Dun Mountain Maitai

Brook Street

Makarewan

W. rostrata

I

Wai~ian

M. planata S. spinosa

Puruhauan

P. multicostata M. woodi

iFormation S =Wooded Pk. Lst.

Mudhiku

Tramway

,

\

.

\

, ..

Guadalupian

Wordian Roadian

Ufimian Kungurian

Cisumlian

Artinskian Sakmadan

E ova~is W. ingelarensis E maxwelli

Barrettian

E.discinia S. supplanta

Irenian Filippovian

Waipapa

C,R,S

\ \ -... \

.

C,R S

\

\ \

\

.

\

.

Mangapirian Telfordian

N home# N. zea/andicus

.

.

.

P,S Productus Creek Group

. \

\ \

FI

. \

\

\

\

\

\

\

.

\ .... \

\

\

\ \

\

\ \.

\ \

\ \.

\\\\,

\\\ \\\

\

\ \.

-

\\

, . . . . . . . \ \ \

".. \... \ \

\\,

\ \ \ \ " . . . . \ \ \ \ "

Sterlitamakian

\ \ \ \ "

. . . . -,, \

-,, \.

\

\

\.

\.

\ \ \ \ \ . . . \ \ \ \ \

\\\\',

-..

-..

\\\ \\\

\.. \ _ . \ . . \ . \ ,. \ -., \ . ,

R radiolarians S shellyfauna ( brachiopods,molluscs, bryozoans, echinoderms)

~. \.

\\\

.

\ \ \ \ \

C conodonts F fusulines P palynomorphs

\

\\\ \\\ \\\ \\\ \\ \

.

\\\\\

S Takitimu Group

. . . . .

\.

\\\\\ ,

Flowers Formation S

\

\

\

\

M. solita E. prideri S. adentata

Asselian CARBONIFEROUS

Rakaia

T. elongata

Flettian

Midian Murgabian Kubergandian

\

\

.

Kazanian

Caples

Kudwao Group S,P

\

Capitanian

WESTERN

I!,ROVINCE

TorlesseSuperterrane

~ \ \ \ \

MV MantleVolcanics WB Wairaki Breccia

Figure 2. Correlation diagram for marine Permian sequences within New Zealand,showing age range of terranes (Brook Street, Murihiku etc.) and relative position of key faunas through geological time. Only relevant lithostratigraphic units are named for any one terrane. Biostratigraphic information from all major terranes and sedimentary basins are included. Jagged lines denote limit of rock record; wavy lines denote unconformity. Shading denotes no known rock record.

~

114

1.1.1. parapara Group There is one known Permian succession within the Western Province, namely the Parapara Group [9]. It has very limited (<10km 2) outcrop area and consists of about 520m of marine and marginal marine quartzose sediments. The Parapara Group sequence is thermally metamorphosed and largely unfossiliferous except for the Flowers Formation (120m thick) and in particular the Cross Member (35m thick). The Cross Member contains a diverse brachiopod and bryozoan dominated shelly fauna with strong eastern Australian affinities indicative of Ufimian-Kazanian age (Guadalupian, Middle Permian) and probably Capitanian. Associated fossils include corals, bivalves, gastropods, rostroconchs and conulariids. No cephalopods, foraminifera, conodonts or radiolarians have been recorded, nor any distinctive prismatic atomodesmatinid bivalve shell debris. Biostratigraphic age is largely based on brachiopod correlations. The oldest unit within the Parapara Group is the unfossiliferous Draco Slate (>200m) of possible Late Carboniferous-Early Permian age. The youngest unit within Parapara Group (Walker Formation; >200m thick) contains detrital zircons suggesting that it cannot be older than Early Triassic [9]. 1.1.2. Median Tectonic Zone The Western Province is separated from the Eastern Province by the Median Tectonic Zone [10], a belt of long-lived subduction-related magmatic rocks that have recently been interpreted as a Cordilleran batholith (Median Batholith) [11, 12], evidence of a major crustal boundary. It includes some intrusives of Permian age. 1.2. Eastern Province The Eastern Province [3] is an assemblage of accreted allochthonous terranes making up northern New Zealand and the Pacific margin in the south. Two distinct groupings of terranes are recognised on the basis of gross composition. The first includes three terranes of island arc association, dominated by volcaniclastic sediment. These are the Brook Street, Dun Mountain - Maitai and Murihiku Terranes, referred to as the Central Arc Terranes (=Hokonui Assemblage [4] ). They occupy a central position between the Western Province and a second eastern group of Eastern Province terranes referred to as the Torlesse Superterrane (=Te Anau and Alpine Assemblages [4] ). The Torlesse Superterrane is an assemblage of five terranes that includes vast areas and volumes of predominantly quartzofeldspathic sediment that must have been derived from dominantly terrigenous granitoid sources located outside the New Zealand sector but still within eastern Gondwanaland. These terranes include Caples, Rakaia, Waipapa, Pahau and Waioeka Terranes [13]. The Waipapa Terrane also includes quartzofeldspathic sediment but is characterised by finer-grained, thinner-bedded lithologies suggestive of a more distal location with respect to an accretionary sedimentary wedge. It also appears to include a greater proportion of rocks of oceanic association (chert, hemipelagite, limestone and basalt) than do other terranes within the Torlesse Superterrane. Within the Eastern Province, fossiliferous marine Permian rocks are known from the Brook Street, Dun Mountain-Maitai, Murihiku, Caples, Rakaia and Waipapa Terranes (Fig. 2). 1.2.1. Central Arc Terranes 1.2.1.i. Brook Street Terrane The Brook Street Terrane is an Early to Late Permian oceanic volcanic arc and includes a 14-16 kilometre thick sequence of moderately metamorphosed volcanic and volcaniclastic

115 rocks of mainly basaltic-andesite composition with minor rhyolitic and dacitic lithologies. It comprises a series of discrete successions, including the fossiliferous Takitimu and Productus Creek Groups. Fossils include bryozoans, corals, brachiopods, rostroconchs, bivalves, gastropods, conulariids, rare nautiloids, fragmentary echinoderms, rare trilobites, fish and plant remains, palynomorphs and trace fossils. No ammonoids, conodonts or radiolarians have been recovered from these rocks. The Takitimu Group is thick and mostly unfossiliferous but does contain several biostratigraphically important fossil horizons [2]. It is overlain conformably by Productus Creek Group [14, 4]. The Productus Creek Group (c.l,000m thick) contains the richest and most diverse Permian faunas known from New Zealand. Recent stratigraphic interpretation [4] suggests that there are just two units within the Productus Creek Group: the Mangarewa Formation and the Glendale Limestone. Two other fossiliferous Permian units previously attributed to the group (Hawtel Formation, Wairaki Breccia) are treated as allochthonous out-of-sequence tectonosedimentary bodies within the Letham Ridge Thrust Fault [4]. One other recent study suggests an even more complex structure for Productus Creek Group, partly on the basis of biostratigraphic interpretation [ 15]. This analysis requires testing but for the purposes of this review the simpler interpretation is adopted [4]. Mangarewa Formation is especially fossiliferous but thin (<150m thick), and has been subject to considerable study with recognition of two local stages (B arretti an and Flettian Stages) and at least five brachiopod zones [2]. The base of the Barrettian Stage is defined within the underlying Caravan Formation [4, 15]. The Mangarewa Formation is the most fossiliferous Permian unit within New Zealand. The age range of the Mangarewa Formation is interpreted to span the Early to Middle Permian (Cisuralian-Guadalupian Series) boundary, and represents Kungurian, Roadian, Wordian and Capitanian time [ 15]. The Glendale Limestone is interpreted as a stack of calc-turbidites (c.300m thick) with only minor volcaniclastic detritus. But for a few thin fossiliferous horizons with low diversity brachiopod and bivalve faunas, it is largely devoid of recognisable shelly fauna. Yet the limestone is almost entirely made up of comminuted prismatic calcite shell debris of fine sand grade, attributed to unidentified atomodesmatinid bivalves. Age of the Glendale Limestone is poorly constrained but is probably Wuchiapingian (Lopingian Series, Late Permian). On the basis of a small brachiopod fauna, basal Glendale Limestone is attributed to the Plekonella multicostata Zone [2, 15]. The Glendale Limestone appears to be of very similar lithofacies, if not identical, to the Wooded Peak Limestone of the Dun Mountain-Maitai Terrane. However, there is insufficient fossil evidence to establish a precise biostratigraphic age for either unit. Detailed Sr87/Sr86 analysis of these sequences may provide some independent means of correlation. Preliminary studies suggest that they have very similar Sr87/Sr86 isotopic compositions [ 17, 18]. Other fossiliferous Brook Street Terrane sequences include the Greenhills Group near Bluff [19, 20], strata described from the Dunton Range near Te Anau [21], the Gondor Formation in the Eglinton Valley [22], the Mantle Volcanics in the Hollyford Valley [23], and rocks in the Nelson City area from which the term 'Brook Street' is derived [24]. 1.2.1.ii. Dun M o u n t a i n - Maitai Terrane This terrane comprises a six kilometre thick, moderately metamorphosed volcaniclastic sedimentary succession, the Maitai Group, resting in primary depositional contact on the Dun Mountain Ophiolite of presumed Early Permian age [25]. The lower 1,000-1,500m of the Maitai Group is presumed to be of Late Permian age but this is not substantiated. Age diagnostic fossils are rare [26, 4]. No Permian ammonoids, fusulines, conodonts or identifiable radiolarians have yet been recognised from the Dun Mountain-Maitai Terrane.

116 Available biostratigraphic age is based on rather imprecise correlations based on a few brachiopod [2], bivalve [27, 28], and gastropod [29] determinations. Autochthonous Maitai Group Permian sedimentary rocks include three units: Upukerora Breccia, Wooded Peak Limestone and Tramway Formation. They comprise redeposited bioclastic sandstone and carbonate lithologies dominated by molluscan prismatic calcite shell debris attributed to unidentified atomodesmatinid bivalves. Well-preserved atomodesmatinid bivalves and other fossils such as chonetid brachiopods and gastropods are rare and indicate low diversity. Trace fossils and plant debris are relatively common within both Wooded Peak Limestone and Tramway Formation. Cherts and black shales are absent. The Wooded Peak Limestone is comprised of calc-turbidites like the Glendale Limestone (Brook Street Terrane) and attains thicknesses of up to 1,000m [24]. The greater part of the Maitai Group (4,500-5,000m) is now known to be of Early to Middle Triassic age on the basis of Early Triassic ammonoid faunas [30]. This Triassic succession is sparsely fossiliferous and largely made up of redeposited sediments. Some units, particularly the Stephens Formation, contain allochthonous fossiliferous Permian olistoliths [31], that were previously considered [24, 2] to be autochthonous and conformable within the sequence. A Permian-Triassic boundary is recognisable on the basis of organic ~513Cisotopic signature [32, 33], near the base of the Little Ben Sandstone that overlies fossiliferous Permian Tramway Sandstone. The only known fossil content of the Little Ben Sandstone is plant debris and rare atomodesmatinid prisms (probably reworked). 1.2.1.iii. Murihiku Terrane The Murihiku Terrane [3] is the least structurally deformed and stratigraphically most coherent of the New Zealand basement terranes. It is weakly metamorphosed (up to zeolite facies) and includes a thick succession (up to 7,850m) of volcaniclastic sediment spanning Permian to Early Cretaceous time, but the great bulk of it is of Middle Triassic to Late Jurassic age. It represents a long-lived arc-related basin, now detached and presumed to be remote from the original location of the volcanic source [34]. The Median Tectonic Zone (Median Batholith) has been considered a possible source but provenance studies of conglomerate clast lithologies suggest otherwise [35]. Several small areas (<10km e) of fossiliferous Permian sequence are exposed within Murihiku Terrane in the Southland Syncline near Mataura and Pukerau (Southland) respectively [24, 36]. These rocks are documented as the Kuriwao Group [24] and comprise up to 850m of sandstone and bioclastic carbonate lithologies. It has long been suspected that these rocks more properly 'belong' to either Brook Street or Dun Mountain-Maitai Terranes. However, new research suggests that the Permian Kuriwao sequence is in primary depositional contact with overlying Triassic and/or Jurassic Murihiku strata in which case it is best interpreted as a Permian 'basement' within the Murihiku Terrane [37]. The Kuriwao Group contains three units: Titiroa Limestone, Pine Bush Formation and Waimahaka Limestone [24]. The limestones are dominated by molluscan prismatic calcite shell debris attributed to atomodesmatinid bivalves. Other fossils are rare but include chonetid and spiriferid brachiopods, atomodesmatinid bivalves, and a few other bivalves and gastropods. The Pine Bush Formation is mostly unfossiliferous but some horizons contain relatively common shelly fossils comprising a low diversity brachiopod, bivalve and gastropod fauna, and also palynomorphs [38]. Kuriwao Group is probably of Late Permian Changhsingian age. No foraminiferans, cephalopods, conodonts or radiolarians are recorded from the Kuriwao Group and there is a complete absence of cherts and black shales.

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1.2.2. Torlesse Superterrane The Torlesse Superterrane is divided into a number of terranes, three of which have a known Permian content: Caples, Rakaia, and Waipapa Terranes. The Torlesse Superterrane is voluminous and constitutes more than 60% of the New Zealand landmass. Originally it could have been 200 x 1,000km in area, and 2-5km thick. It is structurally complex, poorly mapped, and stratigraphic continuity may be difficult to establish for more than a few hundred metres. It may be thought of as a vast accretionary complex of Permian to Cretaceous age comprised of three discrete sedimentary prisms of Permian, Triassic and Jurassic-Cretaceous age. It is metamorphosed, varying in grade from prehnite-pumpellyite to greenschist facies. Permian sequences within Torlesse Superterrane are dominated by clastic sandstone and siltstone lithologies of turbidite aspect, commonly termed 'greywacke', and are mostly composed of redeposited sediments [ 13, 39]. Permian fossils from autochthonous terrigenous clastic sequences are only known from the Rakaia Terrane [40, 41, 42]. Oceanic associations of basalt, limestone, chert and hemipelagite are preserved as regionally minor components within the Torlesse Superterrane [43, 44, 45, 46]. These are commonly involved in olistostromal deposits and/or melanges, and are interpreted as tectonically 'scraped' allochthonous entities, originally derived from either oceanic sea floor association or sea mounts that have become incorporated within the clastic accretionary complex as a result of subduction-related plate margin processes. Fossiliferous Permian localities and sequences of oceanic association are present within the Rakaia and Waipapa Terranes but are not common. In a sense, the record of time within the Torlesse Superterrane has been swamped or diluted by sediment. Attempts to determine 'thickness'of Torlesse sequences are at best crude, but it can be stated with some certainty that rates of deposition were high, of the order of 100s to 1,000s of metres per million years and in some cases >2,000 but <10,000 metres per million years. Fossils are generally rare but definite fossil zonation is possible [40, 41 ].

1.2.2.i. Caples Terrane The Caples Terrane is poorly understood in terms of both stratigraphy and structure, and is virtually unfossiliferous. It comprises >10km of homoclinal and complexly folded greywackes and argillites. The Caples Terrane is metamorphosed, varing in grade from prehnite-pumpellyite facies to lower greenschist facies, and is generally more deformed than other terranes within the Torlesse Superterrane. It is predominantly composed of redeposited sediments that are largely volcanic arc-derived but admixed with a quartzofeldspathic component. It contains allochthonous blocks of conodont-bearing Kungurian (Early Permian) micritic limestone with associated atomodesmatinid shell debris [43]. Pebble clasts with fragmentary atomodesmatinid bivalve fossils have also been recorded from conglomerates. The Caples Terrane includes the sparsely fossiliferous Pelorus Group of Marlborough and Nelson [47]. A few atomodesmatinid bivalve fossils have been recorded but all are of uncertain stratigraphic relationship. Poorly-preserved palynomorphs have been recovered from Ward Formation, and Late Permian radiolarians have been found in chert pebbles that are thought to have been derived from Pelorus Group. The Croisilles Melange lies within the Pelorus Group and has produced one isolated Permian gastropod fauna [48]. Trace fossils and plant fragments are known from a number of localities. Precise age range of the Caples Terrane is unknown. Meagre fossil evidence suggests an Early Permian to Middle Triassic age range but it seems likely that all Permian fossils relate to allochthonous lithologies, and depositional age is most probably Late Permian to Middle Triassic.

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1.2.2.ii. Rakaia Terrane Fossil content of the clastic Rakaia Terrane indicates a depositional age range of Early Permian-latest Triassic. A handful of fossiliferous Permian localities are known from terrigenous clastic successions. These include fragmentary faunas of atomodesmatinid bivalve debris with few identifiable whole valves preserved. A relatively large number of localities within the Rakaia Terrane have been attributed a Permian age based on the presence of prismatic shell or moulds ('holes') of prismatic shell, the assumption being that prismatic shell can only be derived from Permian atomodesmatinid bivalves [40, 42]. A broad Permian age is attributed to these fossil occurrences, but on the basis of distribution and abundance of atomodesmatinid fossils as determined from all other New Zealand and Australian terranes, a Guadalupian to Lopingian (Middle to Late Permian) age is most plausible. Only one poorly preserved Permian brachiopod fauna is known from the Rakaia Terrane [40], and is attributed an imprecise Permian age, though it is most probably of Artinskian to Capitanian age range (late Early to Middle Permian). These few fossils appear to be similar to forms known from the Brook Street, Murihiku and Dun Mountain-Maitai Terranes and demonstrate affinity with eastern Australian faunas. Permian radiolarian faunas have been recovered from allochthonous cherts, particularly in the Wellington area. At Red Rocks [45], radiolarians indicate Ufimian-Kazanian age (Guadalupian; Middle Permian). Fusuline foraminiferans have been recorded from allochthonous limestones at two disparate localities in Canterbury [44] and indicate Murgabian ages (Roadian-Wordian; Middle Permian). Permian conodonts have been recorded from allochthonous hemipelagite sequences near Waimate (south Canterbury). They indicate an age range of latest Asselian to earliest Kungurian (Early to Middle Permian), and constitute the oldest Permian fossils recognised from the Rakaia Terrane [43]. All of these radiolarian, fusuline and conodont occurrences are within areas dominated by terrigenous clastic sediments of Triassic age. 1.2.2.iii. Waipapa Terrane The Waipapa Terrane as used here is restricted to only the 'Bay of Islands Terrane' [49, 50]. However, formerly it has been extended in terms of distribution to include a belt of rocks now mapped as parts of the Caples and Pahau Terranes within both North and South Islands. It ranges in age from Middle Permian to Late Triassic. Tentatively included are rocks of the Aspiring Terrane [4], as well as the Chrystalls Beach Complex exposed on the Otago coast south of Dunedin. These rocks have previously been treated as part of Caples Terrane. Much of the Waipapa Terrane is more oceanic in character than the Caples Terrane, being dominated by fine grained terrigenous sediments that were distal to the accretionary wedge, and with a greater proportion of chert and hemipelagite sequences associated with basaltic rocks. Clastics of Triassic age [51 ] are the youngest rocks within the Waipapa Terrane. Fusuline-bearing limestones are also present within Waipapa Terrane at several localities within the Whangaroa Harbour and Bay of Islands areas of Northland (northern North Island) and are associated with sequences of oceanic association, especially basalts [52, 53]. Other fauna associated with the fusulines includes poriferans (sponges), brachiopods, gastropods, bivalves, calcareous algae and echinoderm remains [54]. The fusulines indicate a Midian age (Capitanian; Middle Permian) and are notably younger than the fusuline faunas from Rakaia Terrane of Canterbury (South Island). A Late Permian-Middle Triassic chert succession is particularly well preserved in coastal exposures at Arrow Rocks, Whangaroa Harbour, Northland [53]. This comprises a thick sequence of fossiliferous radiolarian and conodont-bearing cherts and hemipelagites. The

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actual Permian-Triassic boundary appears to be unrepresented because of local faulting. There are thin black shales preserved within the sequence that initially were thought to indicate the boundary on the basis of organic ~513Cisotopic signature [53]. However, wellpreserved conodont fossils indicate that these shales are younger than the Permian-Triassic boundary [55]. Black shales have not been recognised in other New Zealand PermianTriassic terranes. Radiolarians and conodonts indicate a spectrum of Late Permian to Late Triassic Norian ages for pelagic successions throughout the Waipapa Terrane. 2. NEW ZEALAND PERMIAN CORRELATIONS 2.1 Early Permian: Cisuralian Series 2.1.1 Asselian Earliest Permian faunas are not known in New Zealand though it has been suggested [J. B. Waterhouse, pers. comm.] that an isolated gastropod fauna described from the Croisilles Melange (Caples Terrane) might be Early Permian, or Carboniferous. The gastropod has been attributed a Middle Permian Guadalupian age [48]. 2.1.2. Sakmarian The oldest Permian shelly faunas recognised in New Zealand are of late Sakmarian age and are both from Brook Street Terrane sequences north of Lake Te Anau in northem Southland (southwestem South Island). One locality is within the Gondor Formation (Eglinton Subgroup) [22]. Brachiopods and bivalves suggest an approximate correlation with the Tiverton Formation of the Bowen Basin, Queensland, attributed to the Sterlitamakian Substage, late Sakmarian Stage. The second fauna, more diverse and better preserved, is from a sequence within the Mantle Volcanics Formation (Skippers Range) [23]. This fauna is notable for the presence of the bivalve Eurydesma, not known from New Zealand Permian rocks elsewhere. A possible correlation has been suggested with the Rose's Pride fauna (Bowen Basin), Tiverton Formation and the Berriedale Limestone of Tasmania. 2.1.3. Artinskian The oldest formally named local New Zealand stage is the Telfordian Stage, with a type section based on rocks of the lower Takitimu Group (Brook Street Terrane). Two brachiopod zones have been recognised, the Notostrophia zealandicus and Notostrophia homed Zones. Key elements within these zones include Neospirifer crassicostata (Waterhouse), Tomiopsis plana (Campbell), and T. plica (Campbell), that are known from east Australian sequences of the Bowen Basin (uppermost Tiverton Formation and upper Cattle Creek Formation) of Queensland. This fauna, unlike the older Sakmarian (Sterlitamakian) faunas described above, has not been recognised beyond Bowen Basin (eastern Australia) and the Brook Street Terrane (New Zealand). The upper Takitimu Group (Maclean Peaks and Caravan Formations) contains the type section of the Mangapirian Stage. This sequence is sparsely fossiliferous but two brachiopod zones have been recognised [2], the Spinomartinia adentata and Echinalosia prideri Zones. The most common and best-preserved fossil within this sequence is the brachiopod Attenuatella altilis Waterhouse that is also recognised elsewhere within the Brook Street Terrane (Wesney Siltstone, Alabaster Group; Greenhills Group) [56]. Faunas of the Mangapirian Stage cannot be correlated with any faunas in Australia and are thought to represent Artinskian time that is not represented elsewhere within Australasia [ 15].

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2.1.4. Kungurian Position of the Artinskian-Kungurian boundary is difficult to establish in New Zealand because of the poor fossil record, but it has been suggested that the onset of Kungurian time correlates approximately with the Megousia solita Zone [57, 15] within Caravan Formation. The Kungurian Stage is marked by the appearance of many new genera and species, and the disappearance of many genera characteristic of Early Permian and even Carboniferous age. This change is recognisable world wide, even though conodonts, fusulines and ammonoids may be absent. The typical Kungurian has two major faunas, recognised in the form of the Filippovian and Irenian Substages [2]. Faunas from the top of the Takitimu Group (Caravan Formation) and lower Mangarewa Formation (Letham Formation of [15] ) have been attributed a Kungurian age. These sequences constitute the lower part of the type section of the New Zealand Barrettian Stage [2]. Most prominent is the moderately rich fauna of the Spiriferella supplanta Zone that has a Wyndhamia-like form approaching that of Branxtonia typica Booker from the Elderslie Formation (Sydney Basin, Australia). There are other faunal elements that are close to forms within the Elderslie Formation and one species that is close to a Cathedral Mountain species of west Texas (ie. Kungurian).

2.2 Middle Permian: Guadalupian Series 2.2.1. Roadian Stage Faunas from higher in the Mangarewa Formation are more diverse, and include a number of distinctive species that are shared with the comparatively diverse Echinalosia discinia Zone in the Brae Formation (Bowen Basin, Queensland). This single zone is the only New Zealand fauna regarded as Roadian [15]. A Roadian age has been assigned on the basis of succession rather than any direct link with early Guadalupian faunas.

2.2.2. Wordian Stage Within the type area, the Wordian Stage includes three very diverse benthic faunas in the China Tank, Willis Ranch, and Apple Ranch Members of the Glass Mountains, Texas (USA). The same three-fold subdivision is found in the former standard of the pre-Urals and Russian Platform, represented by the Ufimian, Kalinovian and Sosnovian substages [2]. Three distinctive faunal zones are also represented in Queensland and New Zealand and these have traditionally been correlated in a general way, with the Russian and Texan successions [2, 15]. They include the Echinalosia maxwelli, Wyndhamia ingelarensis (=blakei) and Echinalosia ovalis Zones and in New Zealand they are attributed to the upper Barrettian and lower Flettian Stages [2]. However, recent studies now imply a younger, Capitanian, age for the Echinalosia ovalis Zone [15]. The Echinalosia maxwelli Zone incorporates a small and distinctive fauna from the middle of the Mangarewa Formation. This fauna is recognised in one other locality within Brook Street Terrane (Eglinton Volcanics, Dunton Range) [21]. The same zone is well developed within the Oxtrack Formation (Bowen Basin, Queensland) but is yet to be recognised in the Sydney Basin [2, 15]. There are other links between New Zealand and east Australian faunas, and also with correlative faunas of the Siberian and Canadian Arctic. Even the characteristic Australian genus Terrakea Booker, occurs in the Wordian Stage in Texas but is known as Grandaurispina Cooper & Grant [J. B. Waterhouse pers. comm.].

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Within the Productus Creek Group (Brook Street Terrane), the Mangarewa Formation beds that correlate with Barfield Formation (Bowen Basin, Queensland) are only poorly represented with few fossils.

2.2.3. Capitanian Stage The Capitanian Stage is best known for macro-invertebrate fossils in the Delaware Basin. Direct correlation with New Zealand sequences is made difficult by lack of marine faunal correlatives in east Australia, where coal measure deposition resumed after late Early Permian. Correlation is also complicated by uncertainty over the relationship between Capitanian, at the top of the Guadalupian Series, and Wuchiapingian, at the base of the Lopingian Series. Macrofossil evidence suggests that there is no overlap and that the two stages are entirely separate. New Zealand sequences that are attributed a Capitanian age include the upper part of the Mangarewa Formation (Flettian Stage), which includes the Echinalosia ovalis and Terrakea elongata Zones. Within the Western Province, Parapara Group faunas of the Cross Member (Flowers Formation) have been correlated with Ufimian-early Kazanian time [4, 15] and are probably Capitanian. In eastern Australia, the Echinalosia ovalis Zone marks the top of a fossiliferous sequence in Tasmania, and correlatives are found in the Mulbring Formation of the Sydney Basin.

2.3 Late Permian: Lopingian Series 2.3.1. Wuchiapingian Stage The local Puruhauan Stage, described on the basis of faunas within sequences of the Dun Mountain-Maitai Terrane in the Nelson area [1, 2], is attributed a Wuchiapingian age. Two brachiopod zones are recognised: Martiniopsis woodi and Plekonella multicostata Zones. Within Productus Creek Group, the Plekonella multicostata Zone is represented in the lower Glendale Formation above the Terrakea brachythaera Zone (= T. elongata Zone)[2,15]. Elements of this zone, and the overlying Spinomartinia spinosa Zone, appear admixed in New Caledonia [58, 59] and a few elements, including P. multicostata, are present in the upper South Curra beds of east Queensland [2]. These two faunas (New Caledonia and Queensland) lack diversity and contribute little to correlations, but they may be regarded as Wuchiapingian and possibly Changhsingian in age. Within the Dun Mountain-Maitai Terrane, the Wooded Peak Limestone is attributed a Wuchiapingian age, and correlative sequences are almost certainly preserved within all Permian terranes of the Torlesse Superterrane. Waagenoconcha from the Martiniopsis woodi Zone, though poorly preserved, shows similarities with W. imperfecta Prendergast from the Hardman and Lightjack Members of the Fitzroy Basin, West Australia. This zone is considered to be correlative with the conodontbearing Wuchiapingian lower Chhidru Formation of the Salt Range, Pakistan [15]. Other elements of the New Zealand faunas have affinities with Chhidru faunas, including Martiniopsis woodi and Neospirifer arthurtonensis [2]. The Martiniopsis woodi Zone is best developed in the Dun Mountain-Maitai Terrane and is also represented in the Kuriwao Group (Murihiku Terrane), and in Productus Creek Group (Brook Street Terrane; Nemo and Wether Hill Formations [60] ).

2.3.2. Changhsingian Stage Within New Zealand, the Tramway Formation and local Waiitian Stage, defined from the Dun Mountain-Maitai Terrane, are attributed to the lower Changhsingian Stage. The Waiitian Stage is based on allochthonous fossiliferous sheets and blocks of limestone within Early

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Triassic successions of the upper Maitai Group. The Permian faunas occur within stratified blocks, are well-preserved and are distinctive. New Zealand brachiopods include Marginalosia planata that has been correlated with the Gujo fauna of Japan, and Marginalosia kalikotei Zone of Nepal. Both these faunas are of early Changhsingian age[ 15]. In southeast Queensland, the Tamaree Formation has the gastropod Ananias campbelli Waterhouse. The atomodesmatinid bivalve Trabeculatia is also prominent in the Hivatch fauna of Kolyma, in latest Permian rocks of northeast Russia (Siberia). Both the Spinomartinia spinosa Zone and the Hivatch fauna are difficult to date, showing little in common with the very restricted paleotropical faunas. It has been suggested that some of the fossiliferous Permian allochthonous components within the upper Maitai Group (Stephens Formation) of the Dun Mountain-Maitai Terrane are derived from Brook Street Terrane [57]. Late Changshingian time is represented in New Zealand by the local Makarewan Stage, which is based on a distinctive fauna within the Wairaki Breccia, Productus Creek Group (Brook Street Terrane) [ 1, 2]. This unit is now recognised as 'out of sequence' with respect to the main Productus Creek Group, and lies within the Letham Ridge Thrust fault zone [4]. 3. SUMMARY The correlation of New Zealand and east Australian Permian faunas is made difficult because of the lack of fossils of widely distributed paleotropical pelagic organisms such as fusulines, radiolarians, ammonoids and conodonts. Biostratigraphic correlation based on benthic faunas dominated by brachiopods, bivalves and gastropods is often indirect, through a second or third faunal succession, rather than directly with Russia or the United States. Valuable input into east Australian-New Zealand correlations may be derived from successions in Asia (Salt Range), Canada and east Russia (Siberia). This review has attempted to express the current understanding of the known fossiliferous Permian sequences of New Zealand. Much of it has been drawn from modem assessments of stratigraphy [4, 30, 31] and faunal correlation [15]. New Zealand sequences are expressed in terms of local stages and brachiopod range zones. This review (Figure 2) highlights several major changes in thinking, including the following conclusions: 1) No non-marine sedimentary rocks of Permian age are known from New Zealand. 2) The only Permian faunas within the Western Province are of probable Capitanian age. 3) Brook Street Terrane sequences appear to be representative of most of Permian time, Sakmarian to Changhsingian. 4) The main Productus Creek Group sequence is representative of Kungurian to Wuchiapingian age. 5) Earliest Permian faunas of Asselian age are unknown from New Zealand. 6) Permian sedimentary rocks of the Maitai Group of the Dun Mountain-Maitai Terrane are not older than Wuchiapingian: they are exclusively of Late Permian Lopingian age. 7) The Kuriwao Group of the Murihiku Terrane also appears to be of exclusively Late Permian Lopingian age and may be restricted to Changhsingian. 8) Middle Permian fusuline faunas are known from restricted allochthonous sequences from a few localities within the Rakaia and Waipapa Terranes of the Torlesse Superterrane. 9) Similarly, conodont faunas are only known from a few localities within allochthonous sequences of mainly oceanic association within Caples, Rakaia and Waipapa Terranes of the Torlesse Superterrane. 10) No Permian ammonoids are known from New Zealand.

123 4. ACKNOWLEDGMENTS This review has been enhanced by discussions with J. B. Waterhouse over m a n y years, as well as access to several unpublished manuscripts that he has made available to me. I also acknowledge the constructive input of m a n y other colleagues, including C. J. Adams, Y. Aita, N. Archbold, J. G. Begg, J. D. Campbell, J. M. Dickins, P. Ford, J. A. Grant-Mackie, R. Grapes, E. Krull, C. A. Landis, N. Mortimer, S. Owen, J. I. Raine, K. Rogers, G. Shi, J. E. Simes, A. T a k e m u r a and S. Yamakita. I also thank Professor Yin Hongfu and Dr Tong Jinnan for their encouragement. Michelle Park and Carolyn H u m e constructed the diagrams. REFERENCES 1. J. B. Waterhouse, Proposal of series and stages for the Permian in New Zealand. Transactions of the Royal Society of New Zealand, Geology 5 (1967): 161-176. 2. J. B. Waterhouse, New Zealand Permian brachiopod systematics, zonation, and paleoecology. New Zealand Geological Survey paleontological bulletin 48 (1982): 1-158. 3. D. G. Bishop, J. D. Bradshaw, C. A. Landis, Provisional terrane map of South Island, New Zealand, in D. G. Howell (ed.), Tectonostratigraphic terranes: Houston, Texas, Circum-Pacific Council for Energy and Mineral Resources, Earth Science Series 1 (1985): 515-521. 4. C. A. Landis, H. J. Campbell, T. Aslund, P. A. Cawood, A. Douglas, D. L. Kimbrough, D. D. L. Pillai, J. I. Raine, A. Willsman, Permian-Jurassic strata at Productus Creek, Southland, New Zealand: implications for terrane dynamics of the eastern Gondwanaland margin. New Zealand journal of geology and geophysics 42 (1999): 255-278. 5. R. A. Cooper, A. J. Tulloch, Early Paleozoic terranes in New Zealand and their relationship to 6. T. E. Waight, S. D. Weaver, R. J. Muir, Mid-Cretaceous granitic magmatism during the transition from subduction to extension in southern New Zealand: a chemical and tectonic synthesis. Lithos 45 (1998): 469-482. 7. N. Mortimer, H. J. Campbell, Devonian to Jurassic rocks of New Zealand: classification, content and Gondwana context. Gondwana 9. Ninth International Gondwana Symposium, 10-14 January, 1994, Hyderabad, India (1998): 783-790. 8. N. Mortimer, D. L. Parkinson, J. I. Raine, C. J. Adams, P. J. Oliver, K. Palmer, Ferrar magmatic province rocks discovered in New Zealand. Geology 23 (1995): 185-188. 9. H. J. Campbell, D. Smale, R. Grapes, L. Hoke, G. M. Gibson, C. A. Landis, Parapara Group: PermianTriassic rocks in the Western Province, New Zealand. New Zealand journal of geology and geophysics 41 (1998): 281-296. 10. D. L. Kimbrough, A. J. Tulloch, E. Geary, D. S. Coombs, C. A. Landis, Isotopic ages from the Nelson region of South Island, New Zealand: crustal structure and definition of the Median Tectonic Zone. Tectonophysics 225 (1993): 433-448. 11. N. Mortimer, A. J. Tulloch, R. N. Spark, N. W. Walker, E. Ladley, A. Allibone, D. L. Kimbrough, Overview of the Median Batholith, New Zealand: a new interpretation of the geology of the Median Tectonic Zone and adjacent rocks. Journal of African earth sciences 29 (1999): 257-268. 12. N. Mortimer, P. Gans, A. Calvert, N. Walker, Geology and thermochronometry of the east edge of the Median Batholith (Median Tectonic Zone): a new perspective on Permian to Cretaceous crustal growth of New Zealand. The Island Arc 8 (1999): 404-425. 13. N. Mortimer, Origin of the Torlesse and coeval rocks, North Island, New Zealand. International geology reviews 36 (1995): 891-910. 14. A. R. Mutch, Geology of Morley Subdivision District (S 159). New Zealand Geological Survey bulletin 78 (1972). 15. J. B. Waterhouse, Permian geology of Wairaki Downs, New Zealand, and the realignment of its biozones with the international standard. Proceedings of the Royal Society of Victoria 110 (1998): 235245. 16. B. F. Houghton, Lithostratigraphy of the Takitimu Group, central Takitimu Mountains, western Southland, New Zealand. New Zealand journal of geology and geophysics 24 (1981): 333-348. 17. H. J. Campbell, C. J. Adams, The 'Atomodesma' problem. (Abstract). Geological Society of New Zealand miscellaneous publication 107A (1999): 22. 18. D. L. Kimbrough, E. Krull, C. A. Landis, M. R. Johnston, M.R., H. J. Campbell, Seawater strontium isotopic dating of Late Permian limestone in New Zealand. (in prep.)

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19. D. J. Mossman, L. M. Force, Permian fossils from the GreenhiUs Group, Bluff, Southland, New Zealand. New Zealand joumal of geology and geophysics 12 (1969): 659-672. 20. M. R. Gregory, H. J. Campbell, Permian sea floor, near Bluff. Geological Society of New Zealand miscellaneous publication 49A (1988): 73. 21. I. M. Turnbull, Sheet D42 BD & part sheet D43 - Snowdon Geological map of New Zealand 1:50,000 Map, Department of Scientific and Industrial Research Wellington (1986). 22. J. B. Waterhouse, J. D. Campbell, J. G. Williams, Early Permian brachiopods and molluscs from Gondor Fromation, Eglinton Valley, Southland. New Zealand journal of geology and geophysics 26 (1983): 301-307. 23. J. G. Begg, H. R. Ballard, An Early Permian fauna from the Mantle Volcanics Formation, Skippers Range, northwest Otago. New Zealand joumal of geology and geophysics 34 (1991): 145-155. 24. J. B. Waterhouse, Permian stratigraphy and faunas of New Zealand. New Zealand Geological Survey bulletin 72 (1964): 1-101. 25. D. L. Kimbrough, J. M. Mattinson, D. S. Coombs, C. A. Landis, M. R. Johnston, Uranium-lead ages from the Dun Mountain Ophiolite Belt and Brook Street Terranes, South Island, New Zealand. Geological Society of America bulletin 104 (1993): 429-443. 26. J. B. Waterhouse, Permian brachiopods of New Zealand. New Zealand Geological Survey bulletin 35 (1964): 1-287. 27. J. B. Waterhouse, New Zealand species of the Permian bivalve Atomodesma Beyrich. Palaeontology 6 (1963): 699-717. 28. J. B. Waterhouse, Permian bivalves from New Zealand. Joumal of the Royal Society of New Zealand 10 (1980): 97-133. 29. J. M. Dickins, Youngest Permian marine macrofossil fauna from the Bowen and Sydney Basins, eastem Australia. BMR journal of geology and geophysics 11 (1989): 63-79. 30. S. R. Owen, Ammonoids in the Stephens Formation (Upper Maitai Group), Nelson. Geological Society of New Zealand miscellaneous publication 59A (1991): 109 (Abstract). 31. S. R. Owen, Permian limestone olistoliths, Stephens Formation, Nelson. Geological Society of New Zealand miscellaneous publication 63A (1992): 121. 32. E. S. Krull, G. J. Retallack, H. J. Campbell, G. L. Lyon, M. Schidlowski, Paleoproductivity collapse at the Permian-Triassic boundary in Antarctica and New Zealand indicated by carbon isotopes (5 13 Corg). Abstracts of the Geological Society of America 28 (1996): 54. 33. E. S. Krull, H. J. Campbell, G. J. Retallack, G. L. Lyon, Chemostratigraphic (~13Corg) identification of the Permian-Triassic boundary in the Maitai Group, New Zealand: Evidence for high methane concentrations in an Early Triassic deep marine basin. New Zealand joumal of geology and geophysics (in press). 34. P. F. Ballance, J. D. Campbell, The Murihiku Arc-Related Basin of New Zealand (Triassic-Jurassic). South Pacific Sedimentary Basins. Sedimentary Basins of the World 2, P. F. Balance (ed.). Elsevier Science Publishers, Amsterdam (1993): 21-33. 35. H. Miller, Clues to the provenance of the Murihiku Terrane from clasts within the McPhee Cove Conglomerate, southeast Otago. Geological Society of New Zealand miscellaneous publication 107A (1999): 108. 36. B. L. Wood, The geology of the Gore subdivision. New Zealand Geological Survey bulletin 53 (1956): 1-128. 37. H. J. Campbell, N. Mortimer, J. I. Raine, Permian Kuriwao Group perspectives: terrane, basement or allochthon? Geological Society of New Zealand miscellaneous publication 107A (1999): 23. 38. Y. M. Crosbie, Permian palynomorphs from the Kuriwao Group, Southland, New Zealand. New Zealand Geological Survey record 8 (1985): 109-119. 39. T. C. McKinnon, Origin of the Torlesse Terrane and coeval rocks, South Island, New Zealand. Geological Society of America bulletin 94 (1983): 967-985. 40. J. D. Campbell, G. Warren, Fossil localities of the Torlesse Group in the South Island. Transactions of the Royal Society of New Zealand 3 (1965): 99-137. 41. I .G. Speden, Fossil localities in Torlesse Rocks of the North Island, New Zealand. Journal of the Royal Society of New Zealand 6 (1976): 73-91. 42. C. J. Adams, H. J. Campbell, Fossil zonation and metamorphic geochronology of Rakaia Subterrane (Torlesse Terrane) metasediments in Canterbury, New Zealand (in press). 43. P. B. Ford, D. E. Lee, P. J. Fischer, Early Permian conodonts from the Torlesse and Caples Terranes, New Zealand. New Zealand journal of geology and geophysics 42 (1999): 79-90.

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44. E. Ja. Leven, H. J. Campbell, Middle Permian (Murgabian) fusuline faunas, Torlesse Terrane, New Zealand. New Zealand journal of geology and geophysics 41 (1998): 149-156. 45. R. H. Grapes, S. H. Lamb, H. J. Campbell, B. Sp6rli, J. E. Simes, Geology of the red rocks - turbidite association, Wellington peninsula, New Zealand. New Zealand joumal of geology and geophysics 33 (1990): 377-391. 46. Y. Aita, K. B. Sp6rli, Tectonic and paleobiogeographic significance of radiolarian microfaunas in the Permian to Mesozoic basement rocks of the North Island, New Zealand. Palaeogeography, palaeoclimatology, palaeoecology 96 (1992): 103-125. 47. M. R. Johnston, Geology of the Rai Valley area. Scale 1:50,000. Institute of Geological and Nuclear Sciences geological map 5 (1993). 48. J. M. Dickins, M.R. Johnston, D. L. Kimbrough, C. A. Landis, The stratigraphic and structural position and age of the Croisilles Melange, east Nelson. New Zealand journal of geology and geophysics 29 (1986): 291-301. 49. P. M. Black, "The Waipapa Terrane," North Island, New Zealand: Subdivision and correlation. Geoscience Reports of Shizuoka University 20 (1994): 55-62. 50. C. J. Adams, H. J. Campbell, I. J. Graham, N. Mortimer, Torlesse, Waipapa and Caples suspect terranes of New Zealand: integrated studies of their geological history in relation to neighbouring terranes. Episodes 21 (1998): 235-240. 51. C. D. Blome, P. R. Moore, J. E. Simes, W. A. Watters, Late Triassic Radiolaria from phosphatic concretions in the Torlesse terrane, Kapiti Island, Wellington. New Zealand Geological Survey record 18 (1987): 103-109. 52. E. Ja. Leven, J. A. Grant-Mackie, Permian fusulinid Foraminifera from Wherowhero Point, Orua Bay, Northland, New Zealand. New Zealand journal of geology and geophysics 40/4 (1997): 473-486. 53. A. Takemura, Y. Aita, R. S. Hori, Y. Higuchi, K. B. Sp6rli, H. J. Campbell, K. Kodama, T. Sakai, Preliminary report on the lithostratigraphy of the Arrow Rocks, and geologic age of the northern part of the Waipapa Terrane, New Zealand. News of Osaka Micropaleontologists Special Volume 11 (1998): 47-57. 54. P. A. Moore, Y. Aita, H. J. Campbell, N. De B. Hornibrook, N. Mortimer, R. Wood, Two new Permian faunas in the Waipapa Terrane, New Zealand, and their tectonic-paleogeographic implications. New Zealand journal of geology and geophysics (in press). 55. S. Yamakita, A. Takemura, Y. Aita, R. Hori, Y. Higuchi, K. B. Sp6rli, H. J. Campbell, K. Kodama, T. Sakai, Lower Triassic conodont biostratigraphy of Arrow Rocks in the northern part of the Waipapa Belt, North Island, New Zealand, and lithostratigraphic comparison with Permian/Triassic boundary strata of deep-sea facies in Japan. Geological Society of Japan conference October, 1999 (Abstract). 56. J. B. Waterhouse, The classification and dsecriptions of Permian Spiriferida (Brachiopoda) from New Zealand. Palaeontographica A129 (1968): 1-94. 57. D. J. C. Briggs, H. J. Campbell, Megousia solita from the Permian of New Zealand: Implications for terrane histories. In R. H. Findlay, R. Unrug, M. R. Banks, J. J. Veevers (eds.) Proceedings of the Eighth Gondwana Symposium (1991): 323-331. 58. J. B. Waterhouse, The Permian-Triassic boundary in New Zealand and New Caledonia and its relationship to world climatic changes and extinction of Permian life. Canadian Society of Petroleum Geologists Memoir 2 (1973): 445-464. 59. H. J. Campbell, J. A. Grant-Mackie, J.-P. Paris, Geology of the Moindou-T6remba area, New Caledonia. Stratigraphy and structure of T6remba Group (Permian - Lower Triassic) and Baie de St.Vincent Group (Upper Triassic - Lower Jurassic). G6ologie de la France 1 (1985): 19-36. 60. J. B. Waterhouse, A. R. Mutch, Descriptions and paleoecology of Permian brachiopods from the Nemo Formation, near Ohai, South Island, New Zealand. New Zealand journal of geology and geophysics 21 (1978): 517-530.

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Persian-Triassic Evolutionof Tethysand WesternCircum-Pacific H. Yin, J.M. Dickins,G.R. Shi and J. Tong(Editors) 92000ElsevierScienceB.V. All rightsreserved.

127

Permian-Triassic successions in Japan" key to deciphering Permian/Triassic events Y. EZAKI and A. YAO a aDepartment of Geosciences, Osaka City University, Sugimoto 3-3-138, Sumiyoshi-ku, Osaka 558-8585, Japan

The Japanese Islands consist of several fault-bounded terranes of diverse lithofacies and origins. Shallow- and deep-water sediments, which were deposited in Palaeo-Tethys and Panthalassa, occur as coherent sequences and/or as allochthonous blocks. In recent years, marked progress in radiolarian and conodont biostratigraphy has aided in deciphering the geotectonic framework of the Japanese Islands, the nature of the Permian-Triassic succession, and Permian/Triassic boundary events, especially in pelagic facies. The Japanese Permian-Triassic successions contain high-resolution information on biotic and palaeoenvironmental changes, which not only confirm previous ideas about boundary events, but also reveal the true nature of ocean dynamics near the Permian/Triassic boundary.

1. INTRODUCTION Eastem and southeastem Asia are composite continents, made up of several continental blocks and mobile belts of various sizes and origins. In Southwest Japan, plate subduction-related sedimentary complexes occur in a narrow zone trending approximately in an east-west direction [1]. Shallow- and deep-water sediments, which were deposited in Palaeo-Tethys and Panthalassa, occur as coherent sequences in terranes and/or as allochthonous blocks in accretionary complexes. Research has focused mainly on the genesis of the geotectonic framework within and among terranes. Very recently, the genesis of proto-Japan has been discussed in connection with the spatio-temporal dispersion patterns of Gondwana and neighbouring terranes, including the South China and North China blocks [2]. A series of studies has revealed that the basic geotectonic framework of the Japanese Islands was generated by Palaeozoic and Mesozoic subduction of Panthalassan ocean plates. Until recently, Permian-Triassic stratigraphy and end-Permian extinction events have been extensively studied only in shallow-water deposits in epicontinental shelf settings. Recently, however, marked progress in radiolarian and conodont biostratigraphy has allowed precise stratigraphic correlation of pelagic deposits with their shallow-water equivalents. Consequently, the Permian-Triassic succession and the Permian/Triassic boundary have been recognized in siliceous, deep-water facies as well as in shallow-water carbonate facies that originated in seamount settings [3-5]. These sediments comprise a secular, widespread, high-resolution record of climatic and oceanographic changes. Global-scale events, including

128 mid-Permian and end-Permian extinctions, Permian-Triassic isotopic fluctuations, and the Triassic biotic recovery, have been addressed and elucidated by a variety of workers. This paper provides an overview of Permian-Triassic investigations in Japan, which have progressed markedly in the last decade of this century. The geotectonic framework of the Japanese Islands will be introduced first, followed by a brief discussion of the biostratigraphic framework, particularly for Permian-Triassic pelagic facies. Several fields of research that are closely related to the IGCP 359 Project are documented here, including palaeobiogeography, open-ocean palaeoenvironments, and the end-Permian extinction events, and prospects for future work are also given. Discussions on the origins of each terrane, its development, and local geologic studies have been omitted. For earlier research associated with theoretical and conceptual ideas unique to accretionary tectonics, refer to [2, 6].

2. GEOTECTONIC FRAMEWORK OF THE JAPANESE ISLANDS The Japanese Islands are composed mainly of a series of Palaeozoic to Cenozoic accretionary complexes, which were formed in subduction-related settings. The Tanakura Tectonic Line (TTL) divides the complexes into Southwest Japan and Northeast Japan (Fig. 1). The Median Tectonic Line (MTL) further subdivides Southwest Japan into an Inner Zone on the Japan Sea side, and an Outer Zone on the Pacific side. Both Southwest and Northeast Japan are comprised of several terranes that are each clearly distinguished by their pre-Neogene geological characteristics. The terranes are assigned to pre-Jurassic, Jurassic, and post-Jurassic groups, according to their principal age of formation. For individual studies of terranes, see [6]. Pre-Jurassic terranes in Southwest Japan consist of the Hida-Oki, Hida "Gaien", Akiyoshi, Suo, Maizuru, Ultra-Tanba (= Tamba), and Kurosegawa terranes. Except for the Kurosegawa Terrane, these occur in the northern half of the Inner Zone. The Hida-Oki and Suo are metamorphic terranes, and the others are composed mainly of Palaeozoic to Triassic sedimentary complexes of melange facies and folded strata. These pre-Jurassic terranes occur as subhorizontal nappes upon the Jurassic terranes and form a large-scale imbricated structure. The Hida "Gaien" Terrane, which traditionally has been called the Hida Marginal Belt or the Circum-Hida Belt, is present along the southern margin of the Hida Terrane. The Hida Terrane is composed of melanges that include Ordovician to Permian shallow-water clastics and carbonates, intermediate to acidic volcanics and Upper Palaeozoic metamorphic rocks of high P-T type. The Akiyoshi Terrane is characterized by Upper Palaeozoic accretionary complexes containing huge fossiliferous limestone masses that once capped seamounts in Panthalassa. These Upper Palaeozoic complexes are unconformably overlain by a Triassic shallow-water facies. The Maizuru Terrane is comprised of Palaeozoic ophiolites, Permian strata, and unconformably overlying Triassic sediments. The Permian strata consist of a normal clastic sequence, including limestone and acidic tuff layers that were formed in a marginal marine setting. The Ultra-Tanba Terrane is the tectonically lowest unit among the pre-Jurassic terranes of the Inner Zone, and consists mainly of Permian sedimentary complexes. The Kurosegawa Terrane occurs intermittently as a notable tectonic zone above the Chichibu Terrane in the Outer Zone. The Kurosegawa Terrane may be characterized as a fault-bounded association of quite diverse pre-Jurassic geological bodies, including Palaeozoic igneous rocks (granites), Palaeozoic metamorphic rocks (high P-T schists), serpentinites, Silurian to Triassic normal clastic sequences, and Permian accretionary complexes. The tectonic relationship

129

Pre-Jurassic terranes H~ .

.

.

.

Northeast Japan

Hida-Oki Terrane Hida "Gaien" Terrane Akiyoshi Terrane Suo Terrane Maizuru Terrane Ultra-Tanba Terrane KurosegawaTerrane Southern Kitakami Terrane

JAPAN SEA

Southwest Japan I

n

n

e

r

~

t PACIFIC OCEAN

Outer Zone

Jurassic terranes Chizu Terrane

I

200 km

I

Tanba-Mino-AshioTerrane Chichibu Terrane Northern Kitakami Terrane

TTL: Tanakura Tectonic Line MTL: Median Tectonic Line

Post-Jurassic terranes Ryoke Belt Sanbagawa Belt ~-~ Abukuma Belt Shimanto Terrane

Figure 1. Tectonic division of Southwest Japan (modified from [ 1]).

between the Kurosegawa and the Chichibu terranes is comroversial [7], and has become a focus of wide interest conceming the Palaeozoic and Mesozoic tectonic setting of the Japanese Islands. In Northeast Japan, the Southern Kitakami Terrane is also a pre-Jurassic terrane. It is represented by pre-Silurian granite and metamorphic basement rocks, and Silurian to Jurassic, shallow-water clastics and carbonates. There is a twofold distribution of Jurassic terranes in Southwest Japan. The Chizu Terrane and the Tanba-Mino-Ashio Terrane are in the Inner Zone, and the Chichibu Terrane in the Outer Zone. The Tanba-Mino-Ashio Terrane is tectonically overlain by pre-Jurassic terranes in the north, and passes gradually into a Cretaceous metamorphic belt (the Ryoke Belt) to the south. The Chizu Terrane is represented by Jurassic (approximately 180 Ma) crystalline schists and/or phyllites. Very recently, this terrane and the Suo Terrane were considered to have been closely related to each other metamorphically [8]. The Chichibu Terrane developed as a large-scale nappe tectonically overlying the post-Jurassic terranes (the Sanbagawa [= Sambagawa] Belt and the Shimanto Terrane). These Jurassic terranes consist mainly of

130 Jurassic accretionary complexes containing blocks of various lithofacies that are of different depositional age. These complexes include Lower Carboniferous to Triassic greenstones, Upper Carboniferous to Triassic limestones, Upper Palaeozoic and Middle Triassic to Middle Jurassic cherts, Middle Jurassic acidic tufts, and Upper Triassic to Jurassic clastics. The reconstructed stratigraphy of those blocks is that of an oceanic plate [9] with greenstones as ocean floor basement, limestones as cap rocks of seamounts, cherts as pelagic, deep-sea sediments, siliceous mudstones as hemipelagic sediments, and clastics as trench-fill sediments. This stratigraphy developed through the lateral migration of sedimentary regimes caused by plate motion during Late Palaeozoic through Jurassic time. The variations in depositional ages, lithologic assemblages, and accretionary timing of units in the Tanba Terrane reflect the presence of primary local environments as well as differing accretionary processes [10]. In Northeast Japan, the Northern Kitakami Terrane is also characterized by Jurassic accretionary complexes, and is regarded as the northern extension of the Chichibu Terrane. Post-Jurassic terranes include the Ryoke Metamorphic Belt (low P-T) in the Inner Zone, and the Sanbagawa Metamorphic Belt (high P-T) and the Shimanto Terrane in the Outer Zone. It has recently been proposed that the first two metamorphic belts may represent a spatial association of two contrasting P-T type belts by serendipitous tectonic juxtaposition of contemporaneous belts during arc-parallel displacements, rather than by in situ development of "paired" metamorphic belts [ 11]. The Shimanto Terrane is composed mainly of accretionary complexes formed in Cretaceous to Palaeogene time. The Abukuma Metamorphic Belt in Northeast Japan consists of Cretaceous low P-T metamorphic rocks and granites, and is regarded as the northeastern extension of the Ryoke Metamorphic Belt. While the Permian accretionary zones were formed along the eastern part of the South China Block [2], shallow-water sediments with intercalations of terrestrial sediments were deposited in a shelf-margin setting and are locally overlain by the coveting Triassic sediments. A series of large-scale destruction products of the Akiyoshi reef complex in the Akiyoshi Terrane was described [12, 13]. These were thought to have been generated through large-scale collision-related collapse, internal mechanical destruction, incorporation into accretionary wedges and tectonic stacking. Middle Permian acidic tufts are pervasive in the Hida "Gaien", Maizuru, and Akiyoshi terranes, indicating the geographic proximity to prevailing volcanic activity [ 14].

3. LITHOSTRATIGRAPHY AND BIOSTRATIGRAPHY Lithostratigraphic and biostratigraphic works have been carded out for Permian and Triassic near-shore, shallow-water sediments, and deep-water sediments that are characterized by siliceous facies. The Permian and Triassic strata are in an apparently unconformable relationship in shallow-water successions. The Triassic shelf facies lacks Griesbachian and probably Dienerian strata [15]. It is usually difficult to determine the age of the "lowest" Triassic strata in both shallow- and deep-water successions. The Lower Triassic pelagic facies is characterized by intergradations of black carbonaceous mudstone, siliceous claystone, dolostone, and bedded chert layers. Strata near the Permian/Triassic boundary have facilitated faulting of the succession into several structural blocks. This fault-bounded relationship is genetically related to the detachment process during accretion [ 16]. Palaeozoic to Mesozoic radiolarian biostratigraphic research progressed rapidly in Japan during the 1980s, along with studies of accretionary complexes, and radiolarian zones were

131

Radiolarian zones

fault

Neoalbaillella optima

Neoalbaillella ornithoformis

z r~ W a. LU a. a.

Neo " ! ~ bedded chert claystone

Follicucullus charvetiAlbaillella yamakitai

dolostone hematite nodule I

~ '

fault

Fi Gu o-hachiman

Follicucullus scholasticus Follicucullus ventricosus

-Om

Figure 2. Upper Permian lithology and radiolarian zonation in the Gujo-hachiman and Neo sections of the Mino Terrane [ 17, 18].

established prior to the beginning of the 1990s. Permian and Triassic radiolarian biostratigraphy was studied chiefly in stratigraphically continuous sections of siliceous facies that had been deposited in an open-ocean, pelagic setting and were later accreted to the continental margin. Permian radiolarian biostratigraphy was summarized, based on co-workers' data from the Tanba, Maizuru, and Kurosegawa terranes [19]. Recently the Upper Permian radiolarian zonation for the bedded chert sections of the Mino Terrane was revised [17]. The Gujo-hachiman and Neo sections are composed mainly of bedded grey chert (Fig. 2). There are several intercalations of dolostone layers in the lower part of the Gujo-hachiman section, and hematite nodules or layers in the middle part. Four radiolarian zones are present in the Upper Permian, which contains siliceous claystone layers in the uppermost horizon of the

132

Radiolarian zones II l l l l ]

Spine A2

red chert purple chert

FITITI grey chert El-17 black chert claystone dolostone

Anisian

Triassocampe deweveri II IIIIIIIII

II IIII IIII !1_1111II1! IIIIIIIIIIII

i11111 IIII Sakahogi

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.....

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IIIIIIIIIIII

IIIIIIIIIIII

~.~`..~.`.~}~!~.`~|I~..`..:`.``.~i~`s~.`:.~`~.~i~`:.`.;~`~!~!..`.~i~

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.-

.

-;-----;--:

- ii]

l:.:_::_!:i::::: ::]

-::~'~T:?~:!:"::=

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I

Dienerian

Momotaro-jinja

Eptingium nakasekoi

. . . . . . .

,i~.~,, I,. _

Spathian

Smithian

Triassocampe coronata

Unuma

/

Parentactinia nakatsugawaensis

"Sphaeroids"

-Om

Figure 3. Lower to Middle Triassic lithology and radiolarian zonation in the Inuyama area of the Mino Terrane (modified from [20, 21 ]).

Neoalbaillella optima Zone (Fig. 2). The Neoalbaillella optima Zone was thought to range as high as the uppermost C h a n ~ g i a n on the Yangtze Platform, based on the composition and characteristics of the albaillellarian species [22]. The oldest known Lower Triassic pelagic siliceous facies, according to palaeontological evidence, is the lower Smithian siliceous claystone in the Tanba Terrane, which yields conodonts such as Neospathodus dieneri and N. waageni [23]. Quite recently, the earliest Triassic conodonts Hindeodus parvus and H. minutus were found in black carbonaceous claystone which seems to conformably overlie grey siliceous claystone containing the latest Permian conodonts Neogondolella changxingensis and N. subcarinata [24]. It is now an urgent task to delineate the Permian/Triassic boundary in various sections both sedimentologically and isotopically, as well as palaeontologically. Triassic radiolarian biostratigraphy in the siliceous claystone and bedded chert sections was first examined in the Mino Terrane [25] and recently refined [20, 21 ]. Several sections shown in Fig. 3 are typically exposed along a river in

133

Composite Lithostratigraphy of deep-waterfacies (Mino-TanbaandChichibu)

Horizon

Spine A2 Zone Anisian

Spathian Smithian

Triassocampe deweveri Zone

Neogondolella bulgarica Zone

Eptingium nakasekoi Zone

Neogondolella timorensis Zone

Parentactinia nakatsugawaensis Zone Neospathodus homed Zone Neospathodus triangularis Zone "Sphaeroids" Zone Ns. conservativus - Ns. waaaen Neospathodus dieneri Zone ( Neogondolella carinata, Isarcicella isarcica, Hindeodus parvus, H. minutus)

Griesbachian

Wujiapingian

Neogondolella excelsa Ng. constricta Zone

Triassocampe coronata Zone

Dienenan

Changxingian

Conodont zones in oceanicfacies settings

Radiolarian zones

Neoalbaillella optima Zone Neoalbaillella ornithoformis Zone Follicucullus charvetiAlbaillella yamakitai Zone Follicucullus scholasticus Follicucullus ventricosus Zone

I'1]I! red bedded I - - ~ grey-black ~ chert beddedchert

siliceous claystone ~

Neogondolella changxingensis N. subcarinata Zone Hindeodus typicalis Iranognathus sp. Zone

black mudstone

~

dolostone

Figure 4. Upper Permian to Middle Triassic radiolarian and conodont biostratigraphy of Southwest Japan. Radiolarian zones are after [17, 20, 21 ], and conodont zones are after [4, 26-28].

the Inuyama area, where important studies of Japanese Triassic-Jurassic radiolarian biostratigraphy have been carried out since the 1970s. The lower part of the Momotaro-jinja section and the Hoshakuji section consist of siliceous claystone layers that contain dolostone nodules. The upper part of the Momotaro-jinja section and the Kurusu section consist of alternating beds of siliceous claystone and chert. Black and grey bedded cherts conformably overlie the upper part of these sections. The Sakahogi and Unuma sections are composed mainly of red bedded cherts, along with grey and black bedded cherts. Five Smithian to Anisian radiolarian zones are distinguished in the Inuyama area (Fig. 3). The composite lithostratigraphy of Southwest Japan, ranging from the Upper Permian to the Anisian, is summarized in Fig. 4. Uppermost Permian carbonates are generally poorly developed in seamount settings, although both Permian and Triassic conodonts, ranging from Lower Permian to Upper Triassic (Norian) and including Neogondolella subcarinata and N. changxingensis, are found as mixed assemblages in a calcarenite in the Mino Terrane [29]. The scarcity of uppermost Permian strata is related not only to non-deposition but also to subaerial erosion following the emergence of seamounts. Permian-Triassic stratigraphy and the Permian/Triassic boundary have also recently been precisely documented within seamount-type carbonates in the southem Chichibu Terrane [5]. The lowest part of the Triassic Kamura Formation is earliest Triassic (Griesbachian), based on the occurrence of Hindeodus parvus and Isarcicella isarcica

134 [4]. However, the Permian/Triassic boundary, which is marked by distinct lithologic changes, is thought to be disconformable [5]. The carbonate rocks reached a great thickness but include several disconformities which are indicated by the absence of some conodont zones and the presence of limestone conglomerates and mixed conodont assemblages [5, 26]. These disconformable boundaries may correspond to global, sea-level and climatic fluctuations.

4. PALAEOBIOGEOGRAPHY Palaeobiogeographic studies have been extensively conducted using fusulinids, corals, brachiopods, bivalves, ammonoids, bryozoans, conodonts, and plants in shallow-water and terrigenous facies, and using radiolarians and conodonts in open-ocean, pelagic-water facies. However, many problems concerning faunal and floral successions, affinities, and provinces are still unsolved, partly because of insufficient data about the biota itself, and/or diverse ideas on palaeogeographic reconstruction and subsequent disruption by tectonic movements. Recently, the origins of terranes and their relative geographic positions have been well studied in terms of terrane analysis. The Southern Kitakami Terrane is particularly significant, because it is uniquely composed of "successive" strata, ranging in age from Early Palaeozoic to Mesozoic, with a pre-Silurian basement. It is conjectural as to where its basement originated, and where the terrane was located during Permian and Triassic time. The Inner Mongolian-Japanese Transition Zone was recognized in the Middle Permian, and it is characterized by a mixed Boreal and Tethyan brachiopod fauna and by the Cathaysian flora [30]. This transition zone runs north of the North China Block, through the southern Sikhote-Alin and into the Japanese Islands. The Southern Kitakami Terrane and the Hida "Gaien" Terrane are marked by similar faunal assemblages and lithologic successions, and they were located along the eastern part of the North China Block. Based on ammonoid faunas, the Southern Kitakami Terrane was located in low latitudes in eastern Tethys, together with the South China Block and the Primorye, but separate from the North China Block [31]. This geographic proximity persisted at least until Middle Triassic time. Successions of Permian to Triassic bivalves were discussed in terms of their palaeobiogeographic affinities [32, 33]. Permian bivalves from the clastic facies of the Southern Kitakami Terrane, the Maizuru Terrane, and the Kurosegawa Terrane, in epicontinental or island arc shelf settings, show a close similarity to bivalves from the Yangtze Massif. Triassic bivalve faunas, on the other hand, are closely allied to those in Primorye and Siberia. The area containing Middle Permian fusulinaceans in the eastern Tethys-Palaeopacific region was subdivided into the Monodiexodina Territory, the Colania Territory and the Yabeina Territory [34]. The fauna of the Southern Kitakami Terrane, together with that of Sikhote-Alin and Northeast China, was assigned to the Monodiexodina Territory. On the other hand, the Middle and Late Permian fusulinacean faunas of the Southern Kitakami Terrane were thought to show a striking similarity to those of Sikhote-Alin, South China, Southeast Asia and Tibet [35]. Boreal influence became evident in coral faunas of the Southern Kitakami Terrane and the Hida "Gaien" Terrane in the Middle Carboniferous and persisted into the Early Permian. However, a marked decline of Carboniferous survivors was followed by the widespread development of a waagenophyllid fauna adapted to warm water [36]. This faunal change is thought to have been closely related to global-scale climatic warming, which also replaced the phylloid algal and Boreal Palaeoaplysina reef types with calcisponge reefs in approximately Artinskian time [37]. Based on colonial rugosans characteristic of the Middle Permian coral

135 reef complexes, the Southern Kitakami Terrane was situated in the vicinity of the Indochina and South China blocks [38]. The position of the Southern Kitakami Terrane relative to other terranes during Permian and Triassic time has been discussed, but the main documentation for this lies in the recognition of warm and/or cool climatic factors that affected the fauna and flora of the terrane, rather than geological factors. In general, Early Permian cool-water elements diminished with time and warm-water elements increased rapidly. In addition, the extent of biogeographic realms and/or provinces varies with time in concert with climatic conditions, the migration of biota, and the relative geographic positions among terranes. It is incumbent upon us to thoroughly understand the geological development of reference areas, and to clearly distinguish the areal extent of a given terrane from the geographic extent of the characteristic habitats and climatic factors. Further work is needed to understand not only the geographic changes in biota and environments during Permian-Triassic time, but also their long-range trends, beginning from the origins of the terranes. Such research is now in progress.

5. PERMIAN/TRIASSIC EVENTS IN PELAGIC SETTINGS Permian-Triassic fluctuations in pelagic ocean environments can be reconstructed through investigations of "successive" strata consisting mainly of bedded chert, siliceous claystone, and black carbonaceous mudstone. Biostratigraphic studies of these strata, using radiolarians and conodonts, and lithostratigraphic and geochemical analyses, have delineated the nature of changes in ocean environments and the extinction-recovery patterns and processes [20, 39-43]. Oceanic fluctuations in the Early Triassic have recently received special attention [40, 43, 44]. The following achievements are notable: 1) Favourable habitat conditions persisted until the latest Permian, even in open-ocean, pelagic environments in refugia such as those in near-shore shallow-water settings of the Yangtze Platform [45]. However, the presence of repeated, small-scale intergradations of bedded chert, siliceous claystone, and black carbonaceous mudstone indicates high environmental perturbations in the latest Permian. Increasingly adverse changes finally resulted in the widespread extinction of planktonic organisms (e.g., radiolarians) [20, 46]. Bedded chert again predominated from the Spathian upwards, implying the persistence of favourable conditions for the cyclical blooming of radiolarians. Roughly speaking, the patterns and processes of the end-Permian extinctions, and later biotic recovery in open-ocean, pelagic environments, are identical to those in epicontinental, shallow-water environments [47]. 2) Bedded cherts in the Upper Permian (within the Follicucullus scholasticus- F. ventricosus Zone and upward) to the lower Anisian (within the Eptingium nakasekoi Zone and downward) are mostly dark grey and black, and are thought to have been deposited under low-oxygen ("anoxic") conditions. However, bottom-water conditions progressively changed from "anoxic" to oxic until the Triassocampe deweveri Zone [20, 42, 48]. 3) The provenance of siliceous claystone differs from that of black carbonaceous mudstone. The claystone indicates continuous deposition of volcanic materials and weathering products under anoxic or low-oxygen conditions, following a marked and protracted decline in biotic productivity over a large area [43, 49]. In contrast, the black carbonaceous mudstone has a high content of organic matter, which was derived from marine plankton and bacterial activity. High primary productivity in somewhat oxic conditions occurred repeatedly and intermittently owing to the upwelling of nutrient-rich bottom waters [39, 43]. Although the carbonaceous

136 ,

reefdwelling .....

boundary

,

~END-PERMIAN EXTINCTIONS

['r

Evolutionarybiotic boundary ,

Communitybounda] ~----unconformity~-)~

pelagic

~

Mesozoic-type ~_ ,........:

condensed sections ~

mixed

fauna

Figure 5. Schematic relationships between biotic changes and geologic boundaries near the Permian/Triassic biostratigraphic boundary (modified from [50]). Several events occurred together and interacted in various ways, culminating in the formation of different kinds of boundaries. Organisms disappeared and became extinct based on their survival limitations. Pelagic-type organisms survived later, to the level of the biostratigraphic Permian/Triassic boundary. The end-Permian extinctions proceeded by geographic area as well as by taxon.

mudstones are intercalated with siliceous claystones at several horizons, the black carbonaceous mudstone with fine laminations, adjacent to the "Permian/Triassic boundary", were commonly thought to be indicative of anoxic conditions in a stratified ocean. However, there are diverse ideas on the degree of oxygen-depletion and the duration of the prevailing conditions [40, 42, 51]. On a global scale, various workers have estimated the influence of anoxic events on biotic changes in different ways [52, 53]. 4) A unique combination of lithology and biota in the Lower Triassic, similar to that of a shallow-water platform setting, has also been documented in a buildup on a seamount in Panthalassa [5]. This suggests the ubiquity of protracted inhibiting conditions following end-Permian extinction events, and the resulting prevalence of disaster forms in order to accumulate microbe-induced carbonates. The end-Permian extinctions occurred globally. However, their causes were quite complicated, and their pattems evidently differ by taxon. We must delineate a series of events, and their interactions with and sequential effects on the biota, that culminated in the formation of an array of discontinuous boundaries (see the term "boundary difference" in [50]; Fig. 5),

137 rather than merely study biostratigraphic events at the Permian/Triassic boundary. Increased biostratigraphic resolution of the Permian-Triassic and the Permian/Triassic boundary is, needless to say, inevitable. The Early Triassic witnessed not only the aftermath of a great biotic crisis, but also the recovery of a successor biota. The delay in recovery was due not merely to the severity of previous extinction events, but also to the protracted presence of inhibiting conditions. Recovery processes were an additional aspect of extinction events. The Japanese Permian-Triassic successions, deposited on the open-ocean sea floor, seamounts, and the marginal shelves of island arcs, have the potential to provide invaluable insights into strategies of survival and the nature of refugia. Continuing research will allow us to precisely understand the true nature of the end-Permian events and their phylogenetic significance. Various lines of evidence, especially from the Japanese pelagic regime, not only strengthen previous ideas, but also present many problems to be solved. More research on ocean dynamics is needed near the Permian/Triassic boundary, especially research related to the ocean's structure, its maintenance and destruction mechanisms, related nutrient levels, and other criteria. This will lead to a comprehensive knowledge of Permian-Triassic material-cycling systems and environmental fluctuations and relate them to the development of, and interactions between, the geosphere, biosphere, atmosphere, and hydrosphere. The definition of the erathemic boundary is based on seemingly distinct phenomena in the biosphere, which are deeply rooted in these interrelationships.

'6. A C K N O W L E D G E M E N T S The authors would like to thank Professor Yin Hongfu of China University of Geosciences for providing us the opportunity to contribute this paper and many suggestions. We thank Dr Kiyoko Kuwahara (Osaka City University) for extensive discussions of Permian and Triassic radiolarians. Dr Masayuki Ehiro (Tohoku University) kindly read an early version of this paper and provided many comments. Dr E. W. Bamber (Geological Survey of Canada) kindly revised the English in an early version of our manuscript. This study was supported by grants 09740388 and 11740284 to YE from the Scientific Research Fund of the Japanese Ministry of Education, Science and Culture.

REFERENCES

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Persian-TriassicEvolutionof Tethysand WesternCircum-Pacific H. Yin,J.M. Dickins,G.R. Shi and J. Tong(Editors) 92000ElsevierScienceB.V.All rightsreserved.

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Latest Permian and Triassic carbonates of Russia" new palaeontological findings, stable isotopes, Ca-Mg ratio, and correlation Y.D. ZAKHAROV, N.G. UKHANEVA, A.V. IGNATYEV, T.B. AFANASYEVA, G.I. BURYI, E.S. PANASENKO, A.M. POPOV, T.A. PUNINA AND A.K. CHERBADZHI Far Eastern Geological Institute, Far Eastern Branch, Russian Academy of Sciences, Prospect Stoletiya Vladivostoka, 159, Vladivostok 690022, Russia

The seven recently discovered events, respectively occurring at (1) early Dorashamian, (2) middle Olenekian, (3) early Anisian, (4) latest Ladinian-?earliest Carnian, (5) late Carnian, (6) early Norian and (7) early Rhaetian intervals, are characterised by anomalously high value of 813C (2.5-6.9%o) and a more or less considerable decline in Ca-Mg ratio in organogenic carbonates of the Tethyan Realm The geochemical variations appear explaiable by high bioproductivity of marine basins during periods of transgressions and warm climate. The highest 813C values identified in Triassic limestones of the Malaya Laba (6.9%o) and Sakhrai (4.2%0) River basins in North Caucasus and Primorye region (4.9%o) fall at the middle Olenekian Tirolites-Amphistephanites Zone and its equivalents. Oxygen isotope analyses of well preserved brachiopod shells from the Nikitinskaya and Urushtenskaya Suites show that shallow-water temperatures in North Caucasus fluctuated during Early Dorashamian time about 24oc, which is in agreement with our previous data from the Dorashamian Paratirolites kittli Zone in Transcaucasia (around 22-24oc). Similar temperatures appear to have occured in the Tethys at least during the middle Olenekian time.

1. INTRODUCTION A huge amount of information has been accumulated in support of the concept that high heavy-carbon isotope abundance in the Upper Permian sediments are indicative of high Corg abundance in the late Permian ocean, whereas the abrupt decrease in 813C values in the Permian/Triassic boundary beds coincides with the reduced accumulation of Corg and the development of anoxic conditions [1-12]. At the same time the problem of climatic change in the latest Permian and the earliest Triassic remains a matter for extensive discussion. The Triassic formations in the Alps and adjacent territories contain important geochemical indicators because they are fully represented by carbonate facies. Unfortunately, however, that geochemical investigations at the area have been restricted only by Permian-Triassic and Triassic-Jurassic boundaries till now [ 1,5,13 ]. This paper presents the original data on the latest Dorashamian - early Triassic invertebrate fauna (radiolarians, ammonoids and conodonts) of North Caucasus, stable carbon and oxygen isotope and Ca-Mg ratio values of Dorashamian, Induan, Olenekian, Anisian, Ladinian,

142 Carnian, Norian and Rhaetian organogenic carbonates from Russia and neighbouring territories. In doing so, we have referred to key sections in the Alps (Salzkammergut), North Caucasus, Transcaucasia, Arctic Siberia (Mengilyakh, Buur, Taimir), Koryak Upland (Kenkeren), South Primorye and Sikhote-Alin (Dalnegorsk). 2. M E T H O D S

Isotopic analyses were performed using modernized MI-1201B mass spectrometer at the Stable Isotope Laboratory, Far Eastern Geological Institute, Far Eastern Branch, Russian Academy of Sciences (Vladivostok). The laboratory gas standard is calibrated to V-SMOW and KN-2 standards. The laboratory standard used in the measurements has been calibrated relatively to calcite NBC (National Bureau of Standards) 19 and equals +3.98+0.1%o for oxygen relatively to PDB (Pee Dee belemnite) and -0.75+0.1%o for carbon. Reproducibility of replicate standards was always better than 0.1%o. X-ray and Ca-Mg analyses were also performed in the Far Eastern Geological Institute. 3. 513C,/5180 AND Ca-Mg RATIO IN DORASHAMIAN CARBONATES OF NORTH CAUCASUS Reefogenic limestones and mudstones of the Urushten horizon in North Caucasus have long attracted the attention of investigators, however, debates about their age continue [14-16]. After discovery of the latest Changxingian ceratite Dushanoceras valeriae n. sp. in the uppermost part of the Urushtenskaya Suite of the Malaya Laba River basin one can be confident that the Urushten mudstone in North Caucasus is Late Dorashamian in age, because representatives of the genus Dushanoceras in South China are common for the uppermost layers of the Changxing Formation (Rotodiscoceras beds) [17]. In the light of the new data, the age of some underlying sequences of the Nikitinskaya Suite considers to be Dorashamian. For geochemical investigation we have collected some samples of organogenic carbonates (brachiopod shells with well preserved microstructure and limestones) from the fight bank of the Malaya Laba River near the former small village of Kirovskiy. In descending order, the sequence of Upper Permian sediments in the Malaya Laba River basin (Severnaya, Nikitinskaya and Bezymyannaya Ravines) (Fig. 1) is: Yatyrgvartinskaya Suite (basal layers) - lower Induan 8. Grey sandstone and conglomerate, about 20 m, contains plant remains Elatocladus sp. (V.A. Krassilov's determination). - DisconformityUrushtenskaya Suite - Upper Dorashamian 7. Dark grey mudstone with rare calcareous interbeds, about 20 m, contains bivalves ("Claraia" caucasica Kulikov et Tkachuk), nautiloids (Pseudorthoceras? sp.), and ammonoids (Propinacoceras sp., Neocrimites sp., Vidrioceratidae n. gen. et sp., Changhsingoceras? n. sp. (="Cyclolobus" sp.), Xenodiscus koczirkeviczi Zakharov, and Dushanoceras valeriae n. sp.) [18]. 6. Dark grey reefogenic limestone, about 0.3 m, yields rare brachiopods (locality number 572-7).

143

v

0 2"12

Figure 1. Map showing the location of the study area. 1 - Salzkammergut (Austria); 2-12 North Caucasus: 2 - Rufabgo, 3 - Kuna, 4 - Sakhrai, 5 - Svinyachya, 6 - Mamryuk, 7 Tkhach- Bakh, 8 - Kapustina, 9 - Severnaya, 10 - Nikitina, 11 - Polkovnichya, 12 - Gefo ; 13 Transcaucasia (Akhura); 14-16 - Arctic Siberia: 14 - Mengilyakh, 15 - Buur, 16 - Taimir (Tsvetkov Cape, Keshin Creek); 17-20 - Far East: 17 - Russian Island (Paris Bay, Schmidt Cape), 18 - Ussuri G u l f (Orel Rock), 19 - Sikhote-Alin (Dalnegorsk municipal area). 5. Dark grey mudstone, intercalated with rare lenses of marl, about 15-20 m. 4. Dark grey limestone(572-6). About 0.2 m. Contains sphinctozoans and porifers (Inozoa sp.) (G.V.Belyaeva's determination). 3. Dark grey mudstone, intercalated with thin and rare marl interbeds, about 10-15 m, contains brachiopod Linoproductus sp. (671-1,1a), ammonoid Xenodiscus koczirkeviczi Zakharov, and plant remains - Pteridospermae (V.A. Krassilov's determination). Nikitinskaya Suite - uppermost Lower Dorashamian 2. Dark grey organogenic limestone, intercalated with thin calcareous mudstone interbeds (572-1,2-5), about 50-55 m. Limestone contains many foraminifers (Reichelina, Palaeofusulina, Codonofusiella, Colaniella, etc.) [ 14, 15]. Kutanskaya Suite (upper part) - ? Dorashamian 1. Grey micaceous sandstone and conglomerate, about 30 m, yields foraminifers Nodosaria mirabilis caucasica K.M.-Maklay, Geinitzina sp. and Palaeofusulina cf. P. nana Licharev [18]. 613C anomaly (+4.7%0) has been recorded in limestone of the middle Nikitinskaya Suite (Tables 1 and 2, Fig. 2).

Table 1 Carbon and oxygen isotope analysis of brachiopod shells and limestones from the Dorashamian of North Caucasus (Malaya Laba and.Belaya River basins) 513C 5180 T Sample Material Locality Suite, beds (fossils) (%0, PDB) (%0, PDB) (~ 551-4a Calcitic silvery-white Nikitina Nikitinskaya (basal beds) +2.9 -2.8 23.8* coloured shell Ravine

(Linoproductus) 551-4 572-1

Dark grey limestone -"-

-"Severnaya Ravine

572-2

Grey limestone

.it.

572-3 572-4 572-5 571-1

571-1a 572-6

Dark grey limestone -"-"Calcitic silvery-white coloured shell (Productida) -"Dark grey limestone

.it.

.it_

(2-3 m of the base) _,,. .it.

.it_

+4.3

-3.5

+4.3

-3.5

+4.7

-2.8

+4.4

-3.1

+1.0

-2.9

24.2

+2.2 +2.2

-2.8 -4.9

23.8

+1.0

-4.0

(3 m of the bed 572-3)

Bezymyannaya Ravine

(5 m of the bed 572-4) U r u s h t e n s k a y a (basal beds)

Severnaya Ravine

-2.3 -7.4

(28 m of the bed 572-2)

_It_

t!

+3.8 +3.7

(4 m of the bed 572-1)

.it.

t! Dark grey reefogenic limestone 568-1 Black limestone Gefo * T.F. Anderson and M.A. Arthur's [19] scale.

572-7

.it .it.

.it. .it.

(10-15 m of the base) -"- (15-20 m of the bed 572-6) Cyclolobidae beds

-10.5

Table 2 Ca-Mg ratio in D o r a s h a m i a n limestones of North Caucasus (Malaya Sample Locality Suite, beds 572-1 Severnaya Ravine Nikitinskaya (2-3 m of the base) 572-2 -"-"(4 m of the bed 572-1) 572-3 -"-"(28 m of the bed 572-2) 572-4 -"-"(3 m of the bed 572-3) 572-5 -"-"(5 m of the bed 572-4) 572-6 -"Urushtenskaya '10-15 m of the base) 572-7 -"-"'15-20 m of the bed 572-6) 568-1 Gefo Cyclolobidae beds

Laba and Belaya River basins) Ca, % Mg, % 37.44 0.194

Ca/Mg 192.6

37.96

0.205

184.4

37.21

0.192

192.9

38.61

0.205

188.3

38.42

0.203

188.6

38.00

0.212

178.5

38.04

0.206

184.6

37.11

0.193

192.2

146

Lower Triassic

U.Permian Induan

Dorashamian

Series

Olenekian

Stage '-<

4~

0

r~

"*

ml ~

.+~ "a Cn w~ o ~ l- t

X N. triangularis

laeofusulina ~' ~" ~~"

,-7-X~" _~_

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~ ~~T~

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,.,.

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,

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X

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=-

~ ~

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,~.-~-

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~-o~~ i',,0

i,,,.,~

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147 Figure 2. Dorashamian and Lower Triassic sequence stratigraphic columns of Russia. T isotopic palaeotemperature, T* - isotopic palaeotemperature [20], obtained using of Teiss' "water correction" [21 ], E - event. Normal magnetozones are black, and reverse magnetozones white; sampling gaps are indicated by x [22-24]. References on biostratigraphy: Transcaucasia [16], North Caucasus (original data), South Primorye [25], Siberia [25]. Eventostrat. eventostratigraphy.

4. 813C, 8180 AND Ca/Mg RATIO IN INDUAN AND OLENEKIAN LIMESTONES

4.1. Kapustina Ravine (North Caucasus) The Lower-Middle Triassic sequence in the right bank of the Malaya Laba River (Kapustina Ravine) consists of the following units (in descending order): Malotkhachskaya Suite (basal bed) - lower Anisian 4. Grey massive limestone, about 20 m. Yatyrgvartinskaya Suite - Lower Triassic 3. Grey thin bedded limestone (569-15, 16-18), about 107-137 m, contains radiolarians spherical Spumellaria. 2. Grey massive limestone, about 5-6 m, yields radiolarians (spherical Spumellaria) and undetermined conodonts remains. Turf-clad interval (not less than 20-30 m). 1. Thinly intercalated dark grey mudstone and marl, about 5-6 m, contains rare bivalves Claraia aurita (Hauer). The uniquely high 813C value (6.8%0) and comparatevely high 8180 value (-3.1%o) in limestone of the Kapustina Ravine were recorded at the middle part of the Olenekian (Table 3, Fig. 2); Ca-Mg ratios in limestone of that level indicate higher Mg content as compared with limestones from another levels of the Olenekian (Table 4).

4.2. Svinyachya Ravine (North Caucasus) The section of Olenekian sediments in the Svinyachya Ravine (Sakhrai River basin) consists of the following units (in descending order): Yatyrgvartinskaya Suite - Lower Triassic 7. Dark grey thin bedded limestone, intercalated with interbeds of mudstone (564-27), about 40-60 m. 6. Thin intercalations of dark grey and greyish-green limestone and dark grey mudstone, about 16 m, contains radiolarians (spherical Spumellaria) and ammonoids (Prosphingitoides? sp. and Preflorianites sp.). 5. Dark grey mudstone, with rare thin interlayers of clay limestone, about 25-40 m, yields ammonoid Meekoceras caucasicum Shevyrev, Preflorianites toulai (Smith) and Inyoites ? sp. 4. Thin intercalation of greyish-green limestone, marl and dark grey mudstone (564-24), 5 m, with bivalve Pectinidae. 3. Dark grey thin bedded limestone, 25-35 m.

Table 3 Carbon and oxygen isotope analysis of limestones from the Lower and Middle Triassic of North Caucasus (Sakhrai, Malaya Laba and Belaya River basins) Sample Material Locality Stage Suite, beds 8 13 C 818 0 565-1 565-2

Light grey limestone Grey limestone

Mamryuk

Induan

-"-

-"-

Yatyrgvartinskaya (30-40 m of the base)

(%0, PDB) -0.9

(%o, PDB) -4.9

+0.6

-5.6

(10-15 m ofthe bed 565-1) 565-3 565-4 569-20 569-19 569-18

Light grey limestone Dark grey limestone Grey limestone Dark grey limestone _

II

_

569-17 569-16 569-15 569-14a

569-14

-"II

II

Kapustina Ravine _

it

_

Ii

ii

Dark grey limestone Dark grey limestone _

t!

_

Grey limestone

Olenekian?

t!

Induan

-"-

-4.3

+2.1

-4.8

(15-20 m of the bed 565-3) _,,_

+0.4

-4.6

_"

_

basal beds) +3.5

-5.3

20-30 m of the bed 569-20) _,,_

+5.3

-3.8

40-50 m of the bed 569-19) _,,_

+6.9

-3.2

(25-30 m of the bed 569-18) _,,_

+1.7

-4.4

(25-30 m of the bed 569-17) _,,_

-1.3

-4.5

(20-30 m of the bed 569-16) _,,_

-1.5

-3.9

(2 m of the bed 569-15, 0.5 m below the top) Malotkhachskaya (the base)

- 1.6

-5.3

Olenekian?) Olenekian I!

W!

I!

I!

+0.2

(1 m of the bed 565-2) _,,_

Olenekian (the top) Lower Anisian

Table 3 Sample

Material

569-13

Light grey limestone

569-12

_

569-11 569-10

II

_

Grey sandy limestone Dark grey limestone It

569-9

-

569-8

Greyish-pink limestone Grey limestone

564-16 564-17

-

II

Locality

Stage

Suite, beds

8 13C

8180

(%0, PDB)

(%0, PDB)

+3.5

-7.3

Kapustina Ravine

Lower Anisian

_IV_

_It_

Malotkhachskaya (the base) (10 m of the bed 569-14) _,,_

+1.7

-4.4

_ll_

(5-6 m of the bed 569-13) _,,_

-0.9

-4.6

(10-15 m of the bed 569-12) _,,_

-0.9

-4.8

_ll_

_IV_

_It -

Middle Anisian

_tl -

Svinyachya Ravine -

It

-

Olenekian _

It

_

(12-17 m of the bed 569-11) Acheshbokskaya (15-25 m of the bed 569-10) _,,_

-1.1

-3.8

+1.4

-3.4

(30-40 m of the bed 69-9) Yatyrgvartinskaya (the base)

+1.7

-3.5

+1.8

-3.4

+1.6

-4.1

+1.6

-4.1

+2.0

-3.6

_wt_

(0.3 m of the bed 564-16) 564-18

fl

It

I!

(0.3 m of the bed 564-17) 564-20 564-21 564-22

If

I!

Grey limestone

l!

If

I!

I!

I!

II

(2.0 m of the bed 654-18) _,,_ (0.7 m of the bed 654-20) _,,_ (25-35 m of the 564-21)

Table 3 Sample 564-23 564-29

Material Dark grey limestone Grey limestone

Locality

Stage

Suite, beds

Svinyachya Ravine

Olenekian

_iv_

_it_

Yatyrgvartinskaya (the base) (6 m of the 564-22) _,,_

_it_

10-15 m of the bed 564-23) _,,_

_it_

_tt_

(10-15 m of the bed 564-29) _,,_

_it_

564-25

Greyish-green limestone _,,_

564-26

Grey limestone

_iv_

_it_

(2.5 m of the bed 564-24) _,,_

564-27

Dark grey

_tt_

_tt_

(2.5 m of the bed 564-25) _,,_

564-24

564-6

_vv_

Rufabgo

Olenekian

564-10

_tt

_it_

_wt_

(20-35 m of the bed 564-26) Yatyrgvartinskaya (middle part) _,,_ (2.2 m of the bed 564-6)

8 13C

8180

(%0, PDB) +2.1

(% o, PDB) -4.3

-1.8

-4.3

-2.2

-4.1 _

+4.2

-3.1

+2.3

-4.8

+3.6

-4.6

151 2. Grey thin bedded clay limestone, 6 m, yields radiolarian Spumellaria. Turf-clad interval (about 20 m) 1. Grey pelitomorphic thin bedded limestone (564-16, 18-21), 4.5-5.5 m. There is a tectonical contact with Upper Triassic limestone here. Maxima of 813C values (+4.2%o) and high 8180 value (-3.0%o) have been recorded in the limestone in the middle portion of the Olenekian (564-27) (Table 3). Comparatively high Mg content (Ca/Mg=163.8-170.1) was determined within the Olenekian interval except its lower part (Table 4).

4.3. Mamryuk (North Caucasus The most representative section for the lower part of the Yatyrgvartinskaya Suite is the outcrop exposed along the Mamryuk Creek. In descending order, the sequence of Induan and Lower Olenekian sediments here is: 6. Dark grey middle bedded limestone, about 15-20 m, contains rare radiolarians. 5. Light grey middle bedded limestone (565-3), 20 m. 4. Grey mostly middle bedded limestone (565-2), 1 m, yields rare radiolarians. 3. Light grey massive sandy limestone (565-1), about 15-20 m, contains radiolarians spherical Spumellaria. 2. Light grey coarse-grained sandstone, 10 m. 1. Conglomerate (with predominance of quartz in pebble material), overlying the erosional granitoid surface. Values of 813C in the lower part of the Yutyrgvartinskaya Suite range from -1.2 to +2.2%0 (Table 3); very low Mg contents in limestones were recognized here, as compared with the middle portion of the Olenekian (Table 4).

4.4. Belaya-Rufabgo (North Caucasus) In descending order, the Lower Triassic sequence of the Yatyrgvartinskaya suite exposed along the Belaya River (near the Rufabgo Ravine) is: 4. Grey pelitomorphic thin bedded limestone (564-6,10), about 150-200 m. The middle part of the unit contains radiolarians (spherical Spumellaria- 564-6,10), conodont Neospathodus triangularis (Bender) (564-6), and sponge spicules. 3. Grey sandy limestone, about 30-40 m. 2. Grey and light grey limestone, about 30-40 m. 1. Sedimentary breccia overlying the erosional surface of granitoids, 0.7 m. The highest content of heavy-carbon isotope (813C=+3.6%o) was identified in the bed 56410 of limestone from the middle portion of the Olenekian (Table 3). Ca-Mg ratio at that level reachs 179.14 (Table 4).

4.5. Tri Kamnya (South Primorye) In descending order, the Induan-Olenekian boundary transition in South Primorye (western Ussuri Gulf, Tri Kamnya Cape area, Orel Rock) represented the uppermost portion of the Lazuminskaya Suite is: Olenekian (Hedenstroemia bosphorensis Zone, Gyronites separatus beds) 3. Greyish-green sandstone with lenses and nodules of coquinoid sandy limestone and calcareous sandstone (133-3,401-8, 133-2, 94-14,14a), 3.35 m, yields ammonoid Meekoceras subcristatum Kiparisova, Gyronites separatus Kiparisova and numerous bivalves.

Table 4 Ca-Mg ratio Sample 565-1 565-2 565-3 565-4 569-20 565-1 569-19 569-18 569-17 569-16 569-15 569-14a 569-14 569-13 569-12 569-11 569-10 569-9 569-8 569-5 569-7 569-6 564-16 564-17 564-18 564-20 564-21

in Lower and Middle Locality Mamryuk -"-"-"Kapustina Ravine Mamryuk -"-"-"-"-"-"-"-"-"-"-"-"-"-"-"-"Svinyachya Ravine -"-"-"-"-

Triassic limestones of North Caucasus (Sakhrai, Malaya Laba and Belaya River basins) Stage Suite, beds Ca, % Mg,% Induan Yatyrgvartinskaya (40-50 m of the base) 31.81 Trace -"-"- (10-15 m of the bed 565-1) 29.40 -"Olenekian (?) -"- (1 m o f t h e bed 565-2) 30.18 -"Olenekian -"- (15-20 m o f t h e bed 565-3) 30.01 -"Induan -"- (the base) 38.01 0.220 -"Yatyrgvartinskaya (40-50 m of the base) 31.81 Trace Olenekian (?) -"- (20-30 m o f t h e bed 569-20) 38.20 0.211 Olenekian -"- (40-50 m o f t h e bed 569-19) 38.20 0.219 -"-"- (25-30 m o f t h e bed 569-18) 38.33 0.219 -"-"- (25-30 m o f t h e bed 569-17) 37.68 0.201 -"-"- (20-30 m of the bed 569-16) 37.40 0.194 -"-"- (2 m o f t h e bed 569-15,0.5 m below the top) 37.12 0.184 Lower Anisian Malotkhachskaya (the base) 37.86 0.190 -"-"- (10 m of the bed 569-14) 37.81 0.198 -"-"- (5-6 m of the bed 569-13) 38.11 0.193 -"-"- (10-15 m of the bed 569-12) 38.48 0.196 -"-"- (12-17 m o f t h e bed 569-11) 38.55 0.194 Middle Anisian Acheshbokskaya (15-25 m o f t h e bed 569-10) 38.44 0.189 -"-"- (30-40 m of the bed 569-9) 38.10 0.190 -"-"- (about the same level as the bed 569-8) 37.86 0.200 -"-"- (3-5 m of the bed 569-8) 38.24 0.190 Camian Babukskaya (basal beds) 37.38 0.190 Olenekian Yaturgvartinskaya (basal beds) 37.72 0.210 -"-"- (0.3 m o f t h e bed 564-16) 37.31 0.205 -"-"- (0.3 m o f t h e bed 564-17) 37.33 0.199 -"-"- (2.0 m o f t h e bed 564-18) 37.68 0.216 -"-"- (0.7 m of the bed 564-20) 38.00 0.223

Ca/Mg 172.54 180.61 174.36 174.30 187.31 192.11 200.80 199.26 190.30 196.80 196.30 198.60 202.90 200.10 189.30 201.26 196.73 177.19 181.80 187.43 174.13 169.92

Table 4 Sample 564-23 564-29 564-27 564-28 564-6 564-10

Locality Svinyachya Ravine -"-"-"Rufabgo -"-

Stage Olenekian -"-"Anisian (?) Olenekian -"-

Suite, beds Yaturgvartinskaya (30-40 m of the bed 564-20) -" (10-15 m of the bed 564-23) -"- (35-45 m of the bed 564-29) -"- (100-120 m of the bed 564-27 Yatyrgvartinskaya (middle part) -"- (2.2 m of the bed 564-6)

Ca, % 37.84 37.60 37.30 37.72 38.02 37.86

Mg,% 0.223 0.223 0.219 0.230 0.210 0.210

Ca/Mg 169.30 168.61 170.12 163.80 180.11 179.14

154 Induan (Gyronites subdharmus Zone) 2. Greyish-green sandstone with lenses of coquinoids sandy limestone and calcareous sandstone (133-4), contains rare ammonoid Gyronites subdharmus Kiparisova and many bivalves. 1. Greyish-green sandstone with lenses of coquinoid sandy limestone and calcareous sandstone, 4.5 m, yields bivalve Promyalina shamarae (Bittner). Value of 813C in the upper Induan is +1.2%o. The 813C values at the base of the Olenekian range from +0.3%o to +0.6%0 (Table 5). Somewhat upper, they increase slightly (0.8%0). The base of the Olenekian is characterized by low Mg content (Ca/Mg = 192.8) (Table 6).

Table 5 Carbon and oxygen isotope analysis of sandy limestones from the Induan and Olenekian of South Primorye (western Ussuri Gulf) Zone Beds Sample Locality Stage 813C 8180

133-4

Orel Rock

Induan

Gyronites subdharmus

(%0,

(%o,

-

PDB) +1.2

PDB) -6.5

Gyronites separatus (the

+0.6

-6.3

+0.3

-8.3

+0.4

-7.5

+0.3

-8.0

+0.8

-7.9

(1.5 m below the top) 133-3

-"-

Hedenstroemia bosphorensis Hedenstroemia bosphorensis

401-8

Orel Rock

Olenekian Olenekian

133-2

-"-

-"-

-"-

94-14a -"-

-"-

-"-

94-14

-"-

-"-

-"-

base)

Gyronites separatus (the base) (0.1-0.2 m of the bed 133-3) -"(1.85 m of the bed 133-3) -"(1.0 m of the bed 133-2) -"(0.5 m of the bed 94-14a)

4.6. Russian Island (South Primorye) The middle part of the Olenekian is a sequence of interbedded sandstone and sandy limestone-coquina (Tirolites-Amphistephanites Zone) [26]. It consists of both the Bajarunia dagysi beds (below) and the Tirolites issuriensis beds. The two lenses of white organogenic limestone were recognized in Russian Island. One of them, 1.55 m thick, was found at Paris Bay (16-7,8,10,12,14,16,18). The abnormally high 813C values were discovered in its middle (+4.9%o) and upper (+4.8%o) portions (Table 7). Other lenses of white limestone, 0.6 m thick, exposed at the Schmidt Cape, was also investigated (52P-1,2). Values of 813C in limestone range from +1.7 to +2.2%o. Values of 813C in brachiopod shells discovered 15-17 m upper (Tirolites ussuriensis beds, 52P3-2,3-7) reach +0.07%o.

Table 6 Ca-Mg ratio in Induan Sample Locality 703-1 Polonsky Cape Orel Rock 133-4

133-3 401-8

-"-

and Olenekian Stage Induan (basal beds) Induan (uppermost portion) Olenekian

_iv_

_Iv_

133-2

-"-

-"-

-"-

94-14a

-"-

-"-

-"-

94-14

-"-

-"-

-"-

129-3

Abrek

Induan

129-5a 129-9 130-1

-"-"-"-

-"-"Olenekian

Gyronites subdharmus (15 m below the top) -"- (0.5 m o f t h e bed 129-3) -"- (9 m o f t h e bed 1 2 9 - 5 a ) Hedenstroemia bosphorensis

-"-

(0.1 m of the base) -"- (60 m of the bed 130-1)

132-1

-"-

sandy limestones of South Primorye (western Ussuri Gulf, Abrek Bay and Russian Island Zone Beds Ca, % Mg, % Ca/Mg Gyronites subdharmus (basal 38.12 0.187 202.93 beds) -"31.30 0.264 118.56 (1.5 m below the top)

Hedenstroemia bosphorensis

Gyronites separatus

-"-

-"(0.1-0.2 m of the bed 133-3) -"(1.85 m of the bed 133-3) -"(1.0 m of the bed 133-2) -"(0.5 m of the bed 94-14a) -

31.30 37.60

0.264 0.195

118.56 192.82

33.35

0.265

124.48

33.35

0.260

128.16

32.84

0.249

130.11

31.30

0.255

122.46

-

31.99 33.14 34.86

0.270 0.279 0.275

118.12 118.42 126.33

-

31.12

0.242

128.18

-

156 Table 7 Carbon and oxygen isotope analysis ofbrachiopod shells from the Middle Olenekian Tirolites-Amphistephanites Zone of Russian Island, South Primorye Sample Material Locality Location in 513 C 618 0 (fossil) (beds) the lense, shell length (%0, (%0, PDB) +0.3

PDB) -6.6

above the base above the bed

+1.2 +3.7

-7.0 -6.1

above the bed

+4.9

-6.1

above the bed

+2.6

-5.9

above the bed

+4.8

-6.8

above the bed

+3.9

-5..9

+ 1.7

-5.6

60 cm of the bed 52P-1 +2.2 (the top) L=21 mm +0.3

-6.3

-"-

L =20 mm

+0.7

-6.8

-"-

L=14 mm

+0.5

-7.5

-"-

Paris (Bajaru-

16-7

White limestone

16-8

-"-

-"-

16-10

-"-

-"-

16-12

-"-

-"-

16-14

-"-

-"-

16-16

-"-

-"-

16-18

-"-

-"-

(L) Base

nia dagysi) 30 cm 32 cm 16-8 22 cm 16-10 24 cm 16-12 21 cm 16-14 22 cm

16-16 (the top)

52P-1

t!

Schmidt Cape

The base

(Bajarunia dagysO 52P-2 52P3-2

v!

t! _

_

Calcitic shell

Schmidt Cape

(Fletcherithyris margaritovi

(Tirolites ussuriensis)

-8.0

(Bittner)) 52P3-3

Fletcherithyris sp.

52P3-4 52P3-5 52P3-6 52P3-7

F. margaritovi (Bittner) -"-

Fletcherithyris

-"-

L=I 6 mm L = 18 mm

0.0 +0.4

-7.6 -6.8

sp. -"-

-"-

L=16 mm

0.7

-6.6

5. 513C, 5 1 8 0 AND Ca-Mg RATIO IN MIDDLE TRIASSIC L I M E S T O N E S 5.1. K a p u s t i n a R a v i n e (North C a u c a s u s )

In descending order, the sequense of the Malotkhachskaya Suite (Lower Anisian) at the Kapustina Ravine, the Malaya Laba River basin, is: 4. Greyish-pink massive limestone (569-8), about 30-40 m. Overlying sediments of the Middle Anisian (Acheshbok Suite) and the lower Carnian are represented by (1) intercalations of limestone and mudstone with hematitic-calcareous nodules and (2) conglomerate with brachiopod Costirhynchia sp. correspondingly.

157 3. Grey massive, more or less sandy limestone (569-9,10,11), about 70-90 m, at the neighbouring territory (Tkhach River basin), the suite is characterized by ammonoid Stenopopanoceras, Megaphyllites, Longobarditoides, Laboceras and Leiophyllites [27]. 2. Grey calcareous sandstone and grey massive limestone with interbeds of conglomerate, 10-15 m. 1. Grey massive limestone (569-12,13), about 20 m. The highest content of heavy-carbon isotope (513C = +3.5%0) was identified in the lower portion of the Lower Anisian (Table 3, Fig. 3). Anisian limestone in the Kapustina Ravine is characterized by comparatively low Mg content (Ca/Mg= 190.3-202.9) (Table 4).

5.2. Bolnichnaya (Sikhote-Alin) The Upper Ladinian-?Lower Carnian interval of the Coryphyllia moisseevi beds was recognized along the southwest slope of Bolnichnaya Mount, 450 m from the top (trench 1558) [33]. In the trench, dark grey, almost black, marls with the interbed of light grey limestone, 1.5 m thick, were discovered (GB-15), 8 m. 513C value in limestone reaches +2.6%0 and 5180 in this rock is -2.2%0 (Table 8, Fig. 3).

6. 513C, 5180 AND Ca-Mg RATIO IN UPPER TRIASSIC LIMESTONE 6.1. Kenkeren (Koryak Upland) Upper Triassic rocks in Kenkeren Ridge occur in the upper Nutakingenkyveem River basin (Triasovyj Creek). The Carnian-Norian boundary transition of the Upper Nutakin unit is represented by limestone (119-9), 0.5-26 m thick, siltstone, mudstone, acidic tefroids, and tufaceous conglomerate [34]. Some Carnian-Norian ammonoids (Gonionotites, Juvavites) are known within this interval. We agree with Y.M. Bytchkov and A.S. Dagys' [35] hypothesis that some Triassic reefogenic limestones in Koryak Upland has been originally formed in the tropical zone. In limestone characterized by coral assemblage of Pamiroseris beds, the 513C and 518 0 values are ~[~,ormal>>(+ 1.1%o and -2.2%o correspondingly) (Table 8). In limestone characterized by coral assemblage of Pamiroseris beds, the 813C and 5180 values are normal (+ 1.1%o and -2.2%o correspondingly) (Table 8). 6.2. Salzkammergut (Eastern Alps) The Upper Carnian in stratotypic region of the Upper Triassic (Salzkammergut), as is known, is represented by limestone and dolomite about 8-10 m thick. The abnormally high heavy-carbon isotope abundance (813C = +3.5%o, with 5180= -3.7%o) was discovered by us in the Opponitz limestone of the Stigengraben (5.5 km noah-western of the village of Lunz) (Table 9). It is in contrast with heavy-carbon isotope abundance for Norian Hellkalk of the Dachstein Formation at Donnerkogel (513C= +2.2%o, with 5180=+0.2%o). Recently relatively heavy 513C (2.79%) and 5180 (-1.76%) values were discovered by R. Morante and A. Hallam [13] from the lower K0ssen Formation (Lower Rhaetian) at Kendelbach.

158

~

(/3

C~ r~

-------

Siberia and Omolon

Sikhote-Alin

North Caucasus

Eventostrat. , ,., Biostrati- Rl~*/ Biostrati- ~1 ~'L BiostratiPolar 1~ ~ U ., '~..,/~ go rrnanphhvy _~,, g r a p h y +1+3 g r a p h y coluarl_~la~L.,/,,__~_.. Placites-Rh~. " ~ - ~ ~ ~ ' " Monotis ~ ? buonamici Meandrosty- n listener ~r

T. efimovae ~ E 2 0

.

.

.

.

Gablonzeria kiparisovae

O. ussuriensis

Margarosmi 1ia - - k P. verchomelnikovae .~.L, janicum ,~,, , S. yakutensis

~ Goniojuva~ vites= ~ Pararcestes ~ Proarcestes~ Phloioceras

\

l

IE19

e s
.

,

M. ochotica i

.

,

,

i l Y.pentastichus Volzeia badiotica i ', I Coryphyllia

I ' mo)isseevi

N. seimkanense "P "omkutcha. nicum S. tenuis N. lindstroemi N.mcconn/lli / ~ N. mclea ni

I

.=.

~ Bugunzhites' Parasturia

I. krugi

,!

[

9

'

Tneraensis~ T. constantis

9

E. oleshkoi E nevadanus F. roteliforme ~ 1-'tvcnites-r t. i~ "~ Ph.-Nicomedites

,, L

z Laboceras-Meg.. ~ ]~]Stenopopa,o~l ceras

,

A. kharaulakhensis C. decipiens L. tardus G.taimyrensis

o] \/ /',,9

! i :,

159 Figure 3. Middle and Upper Triassic sequence stratigraphic columns of Russia. Data on magnetic polarity were obtained from Taimir [23,28,29] and North Okhotsk region [23,30]. References on biostratigraphy: North Caucasus [27], Sikhote-Alin [31 ], Siberia [32]. Designation as in Fig. 2.

Table 8 Carbon and oxygen isotope analysis of limestones from the Middle and Upper Triassic of Sikhote-Alin and the Upper Triassic of Koryak Upland (Kenkeren) Sample Material Locality, beds Stage (beds) 813C 8180

GB-15

Light grey limestone

Bolnichnaya Mount

Ladinian-?Lowermost Carnian (Coryphyllia

101

-"-

Verkhnij Rudnik

Lower Carnian (Volzeia

(~

(O/oo,

PDB) +2.6

PDB) -2.2

+2.2

-6.4

+0.9

+0.7

+1.3

-6.0

+3.1

- 1.0

0.0

-14.8

+ 1.1

-6.2

+1.3 + 1.1

-5.7 -2.2

moisseevi) badiotica) VR-10 B-50 308-5

204-1 256-8 239 119-9

Dark grey limestone Dark grey limestone Grey limestone " Grey limestone " Grey limestone

-"-

Upper Camian

( V. badiotica) Bolnichnyj Creek "

Verkhnij Rudnik "

Upper Carnian-Lower Norian Lower Norian

(Margarosmilia melnikovae) Middle Norian (Gablonzeria kiparisovae) Upper Norian

(Meandrostylis tener) -"Kenkeren

-"Upper Carnian-Lower Norian

Table 9 Carbon and oxygen isotope analysis of limestones from the Upper Triassic of the Alps (Salzkammergut) Sample Material Locality Stage, formation 613 C 818 0 892-21 892-9 892-7a

Grey limestone Light grey limestone Grey limestone

Stigengraben

Upper Carnian

Donnerkogel

Lower Norian (Lower Dachstein) Upper Rhaetian (Upper Dachstein)

Gablonz House

(%0, PDB) +3.5

(%0,PDB) -3.7

+2.2

+0.2

+1.7

-3.0

Table 10 Carbon and oxygen isotope analysis of limestones from the Upper Triassic of the Kuna, Sakhrai and Tkhach Rivers and ammonoid shells from the Lower Cretaceous of the Belaya River, North Caucasus Sample Material (fossils) Locality Stage Suite, S 13 C (%0, S 18 0 (%0, beds PDB) PDB) K- 12

Red limestone

Kuna

Lower Norian

K-22

-"-

Bzhebs

K-7

-"-

Upper Sakhrai

t(-9

-"-

-"-

5416

-"-

Tkhach-B akh

5415

-"-

-"-

Norian-Rhaetian boundary beds Upper Rhaetian Upper Rhaetian Norian-Rhaetian boundary beds -"-

5414

-"-

-"-

-"-

5413

-"-

-"-

-"-

5412

-"-

-"-

-"-

564-12

Aragonitic (42%) shell (gigantic ammonoid)

Polkovnichya Ravine

Lower Aptian

Shapkink aya -"-

+2.6

-0.8

+2.8

+0.3

-"-

+2.5

-1.2

Khodzins +2.2 kaya Shapkinskay +2.1 a

-1.9

-"- (1.0 m of the bed 5416) -"- (1.8 m of the bed 5415) -"- (2.0 m of the bed 5414) -"- (1.7 m of the bed 5413) Afibskaya

+2.3

-1.0

+2.5

-0.4

+2.5

-0.4

+2.0

-0.9

-9.2

-1.5

T

(oc)

- 1.8

17.9"

Table 10 Sample 564-12a

Material (fossils) Aragonitic ( 2 1 + 3%) shell ( Tetragonites

Locality Polkovnichya Ravine

Stage

T

-11.8

8180 (%0, PDB) -2.8

Lower Aptian

Suite, beds Afibskaya

!I_

_11 -

-11.7

-2.6

23.9

Upper Lower Aptian

I! -

-6.4

-0.3

13.1

813 C (%o,

PDB)

(oc) 23.8

sp.) 564-13

Aragonitic (37+ -"3%) shell Cheloniceras sp.) 564-14 Aragonitic (68%) Belaya (Abadzekh) shell (Hypophylloceras sp) ++E.L Grossman and T.-L.Ku~H [36] scale

162 The other notable feature in the Kendelbach 13C record is the progressive decrease which occurs between the lower and upper beds of the K0ssen Formation (values of 813 C range from +2.79%0 in below to +1.72 near the top). The later is confirmed by our new data on Upper Rhaetian limestone of the Dachstein Formation at the Gablonz House area (8 13C=1.7% o, 6180=-3.0%o). Very low 813C values fluctuating from +0.47%0 to -1.74%o in overlying carbonates of the Grenzmergel Formation is inferred by R. Morante and A. Hallam [13] to be a result of diagenesis, therefore some evidences obtained from the classic section of Kendelbach does not support, in their opinion, the claim that there was a fall in productivity associated with the end-Triassic mass extinction. 6.3. Dalnegorsk municipal area (Sikhote-Alin) Dalnegorsk limestones have a thickness of up to 480 m (in blocks) [33]. The Lower Norian

Margarosmilia melnikovae beds at Bolnichnaya Mount are characterized by high 813C (+3.1%o) and 8180 (-1.0%o) values. The middle part of the Norian (Gablonzeria kiparisovae beds) in the Verkhnij Rudnik Massif shows low 813C (0.0%o) and 8180 (-6.2%o) values, but it seems to be connected with some diagenetic alterations. The upper part of the section (lower portion of the Meandrostylis tener beds) shows "normal" 813C value (813C=+1.3%o, with 8 180= -5.7%0) (Table 8, Fig.3). 6.4. Kuna (North Caucasus) Lower-Middle Norian strata of the lower Shapkinskaya Suite exposed along the Kuna River (Sakhrai River basin) are represented by conglomerate, sandstone and red limestone (K-12). 8 13C values in latter reach up to +2.6%o (Table 10, Fig. 3); limestone is characterized by high Mg content (Ca/Mg=155.5) (Table 11). 6.5. Sakhrai (North Caucasus) Values of 813 C in Late Norian red limestone of the upper reaches of the Sakhrai River (K-7, 22) range from +2.5%o to +2.8%o; the upper part of the section of red limestone (Rhaetian) (K9) shows "normal" 813C value (+2.2%o) (Table 10). The investigated limestones are characterized by high Mg content (Ca/Mg=146.18) (Table 11). 6.6. Tkhach-Bakh Values of 813C in the Norian-Rhaetian boundary transition of the Tkhach-Bakh Rivers watershed (quarry "Mramor"), represented by red limestone (5412-5416), fluctuate from +2.0%0 to +2.5%0 (Table 10, Fig.3). They are characterized by high Mg content (Ca/Mg=169. 7) (Table 11).

7. 513C AND 8180 IN ARAGONITIC AMMONOID SHELLS FROM THE LOWER APTIAN OF NORTH CAUCASUS A few Lower Cretaceous ammonite shells with more or less intact original aragonitic

163 Table 11 Ca-Mg ratio in Upper Triassic limestones of North Caucasus (Kuna, Sakhrai and Tkhach River basins) Sample Locality Stage Suite (beds) Ca, % Mg,% Ca/Mg K-12 Kuna Norian Shapkinskaya 38.80 0.249 155.50 K-22 Bzhebs Norian-Rhaetian -"39.24 0.268 146.18 boundary beds K-7 Upper -"-"38.18 0.252 151.40 Sakhrai Khodzinskaya 38.46 0.250 153.30 Upper Rhaetian K-9 -"Shapkinskaya 37.09 0.218 169.71 Norian-Rhaetian 5416 TkhachBakh boundary beds -"- (1.0 m of the 37.28 0.215 173.18 5415 bed 5416) -"- (1.8 m of the 37.33 0.207 179.91 5414 " -"bed 5415) -"- (2.0 m of the 37.14 0.198 187.12 5413 -"-"bed 5414) -"- (1.7 m of the 37.88 0.208 182.02 5412 -"-"bed 5413)

material were used for geochemical analyses in comparative purpose. They were collected from different levels of the Aphibskaya Suite. From the lower level (middle Lower Aptian), gigantic undetermined ammonite (aragonitic (42+3%) shell with trace of ~ - S i O 2 and many of CaSO4.2H20) and small Tetragonites sp. (aragonitic (21+3%) shell) were collected. In spite of significant diagenetic alterations, their oxygen isotopic composition seems to be close to the original one and therefore were used for palaeotemperature measurements (Table 10). Two other ammonoids - Cheloniceras sp. (aragonitic (37+3%) shell with trace of c~-SiO2) and Hypophylloceras sp. (aragonitic (68+3%) shell with many of ct-SiO2 and trace of CaSO4.2H20) were obtained from the upper level of the Aphibskaya Suite (uppermost Lower Aptian). They also were used for comparative palaeotemperature investigations.

8. C A R B O N - I S O T O P E S T R A T I G R A P H I C C O R R E L A T I O N S IN THE U P P E R M O S T P E R M I A N ( D O R A S H A M I A N ) AND TRIASSIC

Recently we reported the abnormally high 613C values (+2.8%0) for well preserved brachiopods, Araxathyris ogbinensis Grunt, from the Paratirolites kittli Zone of the Dorashamian in Transcaucasia (Akhura) [37]. Discovery of the abnormally high 613C values in Dorashamian limestone and brachiopod shells of the Nikitinskaya Suite in North Caucasus, just below the siltstone of the Urushtenskaya Suite, charatcterized by latest Dorashamian Dushanoceras, has led us to consider the Nikitinskaya Suite to be an equivalent to the Paratirolites kittli Zone (uppermost lower Dorashamian) in Transcaucasia [37] and the middle Changxing Formation in South China [38] (Fig. 4). G.V. Kotlyar, G.P. Pronina and M.K. Nestell [18] consider Nikitin deposits of North Caucasus to be Late Changxingian in age because they are characterized by

164 foraminifers Colaniella parva (Colani) and some representatives of Palaeofusulina. But according data from South Primorye, Colaniella parva beds locate below the late Changxingian Huananoceras qianjiangense beds [39]. Representatives of Palaeofusulina are known from both the Wushaping [ 17] and Changxing [12] Formations of South China. The Urushtenskaya Suite in North Caucasus may be correlated with the upper Changxing Formation (Rotodiscoceras beds) in South China [12,17], Pleuronodoceras occidentale Zone in Transcaucasia [16] and Huananoceras quianjiangense beds in South Primorye [39,40]. Several 813C anomalies (early Anisian - 3.5%0, Ladinian-?Carnian - 2.6%0, Upper Carnian 3.5%0, and Lower Rhaetian - 2.79%0) is shown in only a single drawing and therefore require additional investigation. The abnormally high 813C values for the Lower Norian were discovered from limestones of two points: the Sikhote-Alin (3.1%o) and the North Caucasus (2.8%0); in the Alps, only a value of 813C at 2.2%0 has been determined within this level. High 813C value (2.79%0) for the Lower Rhaetian (lower K0ssen Formation) has been recognized in the Western Alps [13]. The 813C anomalies discovered in the upper reaches of the Sakhrai River (2.8%0) and Tkhach-Bakh Rivers watershed in North Caucasus seem to be the same in age. Against the background of these data in the Tethys, light 813C values for early and middle Triassic ammonoid shells (with an aragonite content up to 98+2%) from the Buur River, the Olenek River and Taimir, Arctic Siberia [37], stand out sharply, which leads to some problem in correlation of Triassic sediments of the Tethys and the Boreal realm on the basis of data from eventostratigraphy (Figs. 2 and 3). This evidently is a result of a sharp reduction in the Corg content in some Boreal seas during the Late Palaeozoic and early Mesozoic. Recently we confirmed also the validity of the conclusion which we drew earlier that the mentioned mollusks from Arctic Siberia, which characterized by very low 8180 values in their shells also, evidently, lived under reduced salinity conditions[21 ]. The question of what caused the freshening of seas of the Boreal Basin in the Early Mesozoic, ascertained by different methods, and what its scales might have been, remains debatable. If its scales were great, it would be most logical to relate it to the melting of polar ice, which could arise due to cooling during the Palaeozoic-Mesozoic transition. V.I. Ustritsky [41] cites indirect data on existence of Late Permian glacial deposits in the Boreal realm. J.M. Dickins [42], on other hand, doubts the existence of polar glaciers during the Permian-Triassic transition time. Another possible reason for freshening of the marginal parts of the Boreal basin could be entry of fresh water masses from the land as periodically repeating events [43], since allowance can be made for some deviation in climatic conditions in the territory of the Tunguska River basin during the Triassic against the background of the arid conditions prevailing in the Early Mesozoic [44, 45].

9. GLOBAL SIGNIFICANCE There are opposite points of view on the nature of carbon isotope anomalies in marine

165

kD

ce~

~Z

oq

ll'IIllilllgIillll i'lloNil" ~~~.~-~~l-~L~I-~ i.~I~.~

I " Io000~.l_

9

9

~

I IIII IHI

,,..~

rm~

kD

1".

00:

n

;~ r..) :=

~

ug~)A

eE m o~ o~ o

0 c~ (D

I 00"

~

(D

t~

"~,~_.,

t",l

tq cr Oq

o~mS so!.~oS ruo~s,(s

m~

u.:,o.~ I u~:~o,~ l u~:~.~ .~oddfl

z~

lj~ [U| pl~ ~ 1.i1~|S[I.IV ~1~ [~1.i~ i O~l.ii~npl.ii fl,:~)qs~uocI I.II~[IJ.I

olPPlIN

o!ss~pi

/

,IOA~O'-I

I .Ioddl'l

["-fi~!UUOd

Figure 4. Correlation of the u p p e r m o s t P e r m i a n and Triassic of the T e t h y s from geochemical data. 1 - conglomerate, 2 - s a n d s t o n e , 3 - striped s a n d y siltstone, 4 m u d s t o n e , 5 - l i m e s t o n e , 6 - granite, 7 - carbon-isotopic a n o m a l y and its n u m b e r (values in per milles are s h o w n in bracketes), 8 - 813C v a l u e about 2.2%o. Suites" N. Nikitinskaya, Ur. Urushtenskaya, Akhur. Akhurinskaya, Kar. K a r a b a g l y a r s k a y a ; Yatyr. - Y a t y r g v a r t i n s k a y a , M. - M a l o t k h a c h s k a y a , B. Babukskaya, Shapk. - Shapkinskaya, Khodz. - Khodzinskaya, Lazurn. L a z u r n i n s k a y a , T o b . - Tobizinskaya, S . - S h m i d t s k a y a , Zh. - Zhitkovskaya, Karaz. K a r a z i n s k a y a . Formation: O p p . - Opponiz.

-

166 carbonates [2,3,5,46,47], but J.A. Alcala-Herrera, E.L. Grossman and S. Gartner [47] gave, in our opinion, the most convincing answer. Some variation 13C/12C ratios recorded on deepwater marine organic carbonates are related, in their opinion, to variations of different environmental factors, such as the carbon budget, upwelling, and primary productivity. It is difficult to separate the effect of each of these factors for deep-water conditions; but when worldwide carbon isotope shifts are observed in shallow-water carbonates, they are generally attributed to change in primary productivity. The temperature factor is not directly controlling 813C, and biological productivity as a whole depends significantly on some factors including the temperature. The 813C anomalies at different levels of Permian-Triassic carbonates in Primorye region, North Caucasus, Transcaucasia and the Alps, which are usually characterized by high Mg content, seem to be related to high biological productivity of the Tethyan marine basins caused by conditions of transgressions and warm climate during the subsequent epochs: (1) early Dorashamian (Paratirolites kittli Zone), (2) middle Olenekian (TirolitesAmphistephanites Zone), (3) early Anisian, (4) late Ladinian-?earliest Carnian, (5) late Carnian, (6) early Norian and (7) early Rhaetian. The highest bioproductivity for Triassic time took place, apparently, in middle Olenekian. The existence of the thermal maxima in the Tethys during early Dorashamian, middle Olenekian, early Anisian, and early Norian times seems to be in good agreement with some radiolarian diversification events. Abundance and high taxonomic diversity of the Albaillellaria from the lower Dorashamian cherts of the Pantovyj and Skalistyj Creek basins and Amba Mount area (Sikhote-Alin) and from contemporaneous flyschoid strata of the Orel Mount area (South Primorye) seem to be caused by optimal temperature conditions. Accumulation of significant mass of radiolarian cherts in Sikhote-Alin during the Olenekian is probably related to similar conditions. It is possible that appearance of the polysegmental Nassellaria were related to the Anisian warmth and transgression, although the spherical Spumellaria, as was recently recognized in North Caucasus and South Primorye (Abrek Bay), was a dominant group in both the Induan-Olenekian strata and the Olenekian-Anisian transition. The sharp changes in taxonomic diversity both of the Nassellaria and the Spumellaria in cherts of Sikhote-Alin (Skalistyj Creek, Dalnegorsk and Breevka village areas) and development of limestone with the planktonic remains in the Dzhaurskaya Suite and its equivalents in Sikhote-Alin appear to have been related to the Carnian and Norian warm climate. Judging from the data on isotopic investigations, calculated palaeotemperature for the latest Early Dorashamian shallow water carbonate facies of Transcaucasia [37] and North Caucasus [20] reachs 23.8~ (Fig. 2). In the beginning of Urushtenian (late Dorashamian) time temperature of near bottom waters of the shallow sea in North Caucasus (23.8o-24.2 o C) was similar to those for the early Dorashamian. The same temperature conditions of tropic and subtropic seas are suspected to have existed in the Tethys for at least in middle Olenekian time based on some isotopic and Ca-Mg ratio data. Conditions for the middle Olenekian seem comparable also with the early Aptian climatic optimum (with palaeotemperature for shallow water terrigenous facies in North Caucasus about 13.7-23.9~ R. Morante and A. Hallam [13] have reconstructed tropical conditions for the Eastern Alps in early Rhaetian from oxygen-isotopic investigation of the K0ssen limestone (8180=-1.76%o to -2.89%0; T=1924~ Similar result for the Upper Triassic of the Alps (values of 8180 range from -0.05%0 to -2.83%0) from ammonoid aragonitic material was obtained earlier by F. Fabricius, H. Friedrichsen V. Jacobshagen [48].

167 The range of 6180 values in the aragonitic ammonoid shells from the Lower and Middle Triassic in Arctic Siberia suggests the average temperature values for early Olenekian, late Olenekian and late Anisian to be 8.8? ~ 16.2? o and 15.4?~ respectively [20], which is consistent with palaeotemperatures obtained from Olenekian bivalves probably living in some fully saline basins of Arctic Siberia [48]. We indicate the temperature values with questionmarks because they were obtained using R.V. Teiss~t!21 ] "water correction". Whether or not is there a correlation between palaeomagnetic and carbon-isotopic events during the latest Palaeozoic and early Mesozoic time is uncertain at present due to lack of full information on sequence stratigraphic analyses of the key sections. For discussed here reconstruction of late Palaeozoic and early Mesozoic environments the data from reef distribution seem to be very important, because reefs are generally considered to be a very sensible indicator for marine environment changes [50]. A good example of a prospering reef is that of the end-Permian strata of the Urushtenskaya Suite in North Caucasus. It is known that at the start of the Triassic, reefs disappeared from the face of the earth and a reef formation was not renew in any region of world in both the middle Olenekian climatic optimum (transgression) and the similar condition of the beginning of Middle Triassic. After the Permian-Triassic boundary ecological crisis reefs did not returned in the tropical zone till the Late Triassic (although scleractinian corals made their first appearance in the Middle Triassic). Lack of reefs in the low latitudes during the beginning of the Triassic is probably most likely to be connect with 0 2 deficiency of that time as a consequence of the anoxic event across the Permian-Triassic boundary [2,3,50,51]. The absence of discemible signs of organic SiO 2 - accumulation just in the Permian-Triassic transition time and the low rates in reconstruction of the radiolarian taxonomic diversity through the Induan and Olenekian to the early Anisian seem to have been caused by the same reason.

10. P A L A E O N T O L O G I C A L DESCRIPTION Family Pseudotirolitidae Zhao, Liang et Zheng, 1978 Dushanoceras valeriae Zakharov, n. sp. Pseudotemnocheilus sp. Zakharov, 1986: p. 280, pl. 1, fig. 4, 5 [16].

Holotype. DVGI 20/820; North Caucasus, the left bank of the Malaya Laba River near the village of Kirovskiy, Bezymyannaya Ravine, at the slope 60 m below the upper road, locality 572-9; Upper Dorashamian, Urushten mudstone, 12 m below the top. Description (Fig. 5). Shell discoidal, evolute with varying from fastigate (with the weak median keel) in the early whorls to flat in the last volution and marked by reversed V-shaped ribs. Lateral sides rather narrow, including the umbilicus, becoming wider and flat at maturity, marked by strong ribs and ventro-lateral nodes. The ventro-lateral shoulder varies from subangular to angular. The whorl section is reversed trapezoid.

168

valeriae Figure 5. Dushanoceras Zakharov, n. sp.; DVGI 20/820 (locality 572-9), x 1: a- view from lateral side, b view from ventral side; North Caucasus, Malaya Laba River near the former small village of Kirovskiy; Upper Dorashamian.

Measurements (mm) and correlation: Specimen N ~ DVGI 20/820

D

H

W

U

H/D

W/D

47.6

15.0

16.0

19.3

0.32

0.34

U/D 0.41

Suture ceratitic (Fig. 6). U-lobe deep, with strong denticulation at the base. U1- lobe is half of U with strong denticulation also. Lateral saddles narrow. Etymology. This species is named after Russian palaeontologist (Vladivostok), died in 1997. Remarks. New species very similar to a single representative of the D. rotalarium Zhao, Liang et Zheng - from the Changxing Formation of South China [17], but the North Caucasus species is characterized and the narrower the third lateral saddle of suture line.

C

Figure

/

genus Dushanoceras (Rotodiscoceras beds) by more evolute shell

6.

Dushanoceras

A

_.........."

Valeriya S. Rudenko

Suture

of

valeriae

Zakharov, n. sp., DVGI 20/820 (locality 572-9): A, at H=6.5 mm; B, at H=3.0 mm; M a l a y a Laba River near the former small village of K i r o v s k i y , U p p e r Dorashamian.

Distribution. North Caucasus, Upper Dorashamian. Material. Three specimens from the uppermost part of the Urushtenskaya Suite, the left bank of the Malaya Laba River (in association with g(g'laraia~ caucasica Kulikov et Tkachuk and Xenodiscus koczirkeviczi Zakharov).

169

ACKNOWLEDGEMENTS We gratefully acknowledge Dr. G.V. Kotlyar (S.-Peterbourg), Dr. A. Baud (Lausanne) and Dr. T.N. Pinchuk (Krasnodar) for organization of the expedition in North Caucasus in 1997, Dr. V.Y. Vuks (S.-Peterbourg) for the Upper Triassic limestone samples from the watershed of the Tkhach and Bakh Rivers, Dr. G.V. Belyaeva (Moscow) for preliminary determination of some Dorashamian fossils (porifers and sphinctozoans) from the Malaya Laba River basin, Prof. V.A. Krassilov (Moscow) for palaeobotanic determination, Dr. V.V. Golozubov (Vladivostok) for consultation and Mrs. L.I. Sokur for technical help. Our thanks are due to Prof. Guang R. Shi (Australia) for assistance with the manuscript. This research was made under the financial support of Grant PTP95-96/17, R F B R (Russia) Project 97-05-65832 and partly of Project 359 IGCP.

REFERENCES 1. A.M. Baud, M, Magaritz and W.T. Holser, Permian-Triassic of the Tethys: carbon isotope stratigraphy. Geol. Rundschau, 78 (1989)649. 2. L.A Bemer, Drying, 0 2 and mass extinction. Nature, 340 (1989) 603. 3. M. Gruszczynski, S. Halas, A. Hoffman and K.H. Malkowski, A brachiopod calcite record of the oceanic carbon and oxygen isotope shifts at the Permian/Triassic transition. Nature, 337 (1989) 64. 4. W. Holser and M. Magaritz, The Late Permian carbon isotope anomaly in the Bellerophon basin, Carnic and Dolomite Alps. Jb. Geol. Bundesanstalt, 128, no.1 (1985) 75. 5. W.T. Holser, H.P. Schoenlaub, K. Boeckelmann and M. Magaritz, The Permian-Triassic of the Gartnerkofel- 1 core: synthesis and conclusions. Abhandl. Geol. Bundesanstalt, 45 (1991) 213. 6. M. Magaritz, R. Bar, A. Baud and W.T. Holser, The carbon isotope shift at the Permian/Triassic boundary in the southern Alps is gradual. Nature, 331 (1988) 337. 7. M. Magaritz and W.T. Holser, The Permian-Triassic of the Gartnerkofel-1 core (Carnic Alps, Austria): carbon and oxygen isotope variation. Abhandl. Geol. Bundesanstalt, 45 (1991) 149. 8. M. Magaritz, P. Turner and K.-Ch. Kading, Carbon isotopic change at the base of the Upper Permian Zechstein sequence. Geol. Jb., 16 (1981) 243. 9. M. Magaritz and P. Turner, Carbon cycle changes of the Zechstein sea: isotopic transition zone in the Marl Slate. Nature, 297 (1982) 389. 10. H. Oberhanski, K.J. Hsu, S. Piasecki and H. Weissert, Carbon-isotope anomaly in Greenland and in the southern Alps. Historical Biology, 2 (1989) 37. 11. P.B. Wignall and A. Hallam, Griesbachian (Earliest Triassic) palaeoenvironmental changes in the Salt Range, Pakistan and southest China and their bearing on the Permo-Triassic mass extinction. Paleogeography, Palaeoclimatology, Palaeoecology, 102 (1993) 215. 12. H. Yin (ed.), The Palaeozoic-Mesozoic Boundary Candidates of Global Stratotype Section and Point of the Permian-Triassic Boundary. China Univ. Geosci. Press, Wuhan, 1996. 13. R. Morante and A. Hallam, Organic carbon isotopic record across the Triassic-Jurassic boundary in Austria and its bearing on the cause of the mass extinction. Geology, 24 (1996) 391. 14. G.V. Kotlyar, Y.D. Zakharov, B.V. Koczyrkevicz et al., Evolution of the Latest Permian Biota, Dzhulfian and Dorashamian Regional Stages in the USSR, Nauka, Moscow, 1983 (in Russian). 15. G.V. Kotlyar, Y.D. Zakharov, G.S. Kropatcheva et al., Evolution of the Latest Permian Biota, Midian Regional Stage in the USSR, Nauka, Moscow, 1989 (in Russian). 16. Y.D. Zakharov, Type and hypotype of the Permian-Triassic boundary. Mem. Soc. Geol. It., 34 (1988) 277. 17. J. Zbao, X. Liang and Z. Zheng, The Late Permian cephalopods of South China. Palaeontol. Sinica, new ser. B, 12 (1978) 1.

170

18. G.V. Kotlyar, Y.D. Zakharov, G.P. Pronina and M.K. Nestell, Changhsingian deposits of the northwestern Caucasus. Riv. It. Paleont. Strat. (in prep.). 19. T.F. Anderson and M.A. Arthur, Stable isotopes of oxygen and carbon and their application to sedimentologic and palaeoenvironmental problems. SEPM Short Course, 10 (1983) 1. 20.Y.D. Zakharov, N. G. Ukhaneva, A.K. Cherbadzhi and A.M. Popov, Main trends in Permo-Triassic shallow-water temperature changes: evidence from oxygen isotope and Ca-Mg ratio data. XIV International Congress on the Carboniferous-Permian (August 17-21, 1999, Calgary), Program and Abstracts. Calgary (in press). 21. Y.D. Zakharov, D.P. Naidin and R.V. Teiss, Oxygen isotope composition of the Early Triassic cephalopod shells of Arctic Siberia and salinity of the boreal basins at the beginning of Mesozoic. Izvestiya AN SSSR, Ser. Geol., 4 (1975) 101 (in Russian). 22. G.V. Kotlyar, R.A. Komissarova, A.N. Khramov and I.O. Chediya, Paleomagnetic characteristics of Upper Permian sediments of Transcaucasia. Doklady AN SSSR, 276 (1984) 669 (in Russian). 23. Y.D. Zakharov and A.N. Sokarev, Permian-Triassic Biostratigraphy and Paleomagnetism of Eurasia. Nauka, Moscow, 1991 (in Russia). 24. M.W. Hounslow, A. Mt~rk, C. Peters and W. Weitschat, Boreal Lower Triassic magnetostratigraphy from Deltadalen, Central Svalbard. Albertiana, 17 (1996) 3. 25. Y.D. Zakharov, The Induan-Olenekian boundary in the Tethys and Boreal realm. Ann. Mus. Civ. Rovereto, Sez. Arch., St. Nat., 111 (1996) 133. 26. Y.D. Zakharov, Ammonoid evolution and the problem of the stage and substage division of the Lower Triassic. Mere. G+ologie (Lausanne), 30 (1997) 121. 27. A.A. Shevyrev, Triassic ammonites of northwestern Caucasus. Trudy Paleontol. Inst. RAN, 264 (1995) 1 (in Russian). 28. B.I. Gusev, Horisontal movements of the crust during the formation of the Mesozoic flexures and adjacent structures of the central part of the Soviet Arctic. Geotektonicheskie predposylki k poiskam poleznykh iskopaemykh na shelfe Sevemogo Ledovitogo okeana, NIIGA, Leningrad (1974) 68 (in Russian). 29. B.I. Gusev, Spreading structures of oceanic crust in the base of the East Siberian plate. Geophizicheskie metody razvedki v Arktike, 10 (1975) 9 (in Russian). 30. N.B. Lozhkina, Magnetic characteristics of rocks from the basic section of the Upper Triassic in North Okhotsk region. Magmatizm gomykh porod i paleomagnitnaya stratigraphiya vostoka i severo-vostoka Azii, DVNC AN SSSR, Magadan (1981) 59 (in Russian). 31. T.A. Punina, Classification and correlation of Triassic limestones in Sikhote-Alin on the basis of corals. Late Palaeozoic and Early Mesozoic Circum-Pacific Events and Their Global correlation, World and Regional Geology 10, Cambridge Univ. Press (1997) 186. 32. N.I. Kurushin, Triassic bivalves of north-eastern Asia. Autoreferat. dissertatsii na soiskanie uchenoj stepeni doktora geologo-mineralogicheskikh nauk, Sibirskoye . otdelenie . Rossijskoj akademii nauk, Novosibirsk, 1998 (in Russian). 33. T.A. Punina, Stage of Late Permian biogenic buildups in Southern Primorye. M+m. G+ologie (Lausanne), 30 (1997) 151. 34. G.K. Melnikova and Y.M. Bytchkov, Late Triassic fauna of the Koryak Upland and its significant for paleogeographic and paleotectonic reconstructions. Korrelyatsia permo-triasovykh otlozhenij vostoka SSSR. DVNC AN. SSSR, Vladivostok, (1986) 63 (in Russian). 35. Y.M. Bytchkov and A.S. Dagys, Late Triassic fauna of the Koryak Upland and its significant for the palaeogeographic and palaeotectonic reconstruction. Stratigraphiya i flora triasa Sibiri. Nauka, Moskva, (1984) 8 (in Russian). 36. E. L. Grossman and T.-L. Ku, Oxygen and carbon isotope fractionation in biogenicc aragonite: temperature effects. Chemical Geology, 59 (1986), 59. 37. Y.D. Zakharov, N.G. Boriskina, K. Tanabe et al., A change in the salinity of seawater in Boreal Basin during Early-Middle Triassic: evidence from oxygen isotope data. Shallow Tethys 5, Chiang Mai (1999) 165.

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38. J. Chen, M. Shao, W. Huo and Y. Yao, Carbon isotopes of carbonate strata at Permian-Triassic boundary in Changxing, Zhejiang. Sci. Geol. Sinica, 1 (1984) 88 (in Chinese). 39. Y.D. Zakharov and A.V. Oleinikov, New data on the problem of the Permian-Triassic boundary in the Far East. Canad. Soc. Petrol. Geol., Mem., 17 (1994) 845. 40. Y.D. Zakharov, A. Oleinikov and G.V. Kotlyar, Late Changxingian ammonoids, bivalves and brachiopods in South Primorye. Late Palaeozoic and Early Mesozoic Circum-Pacific Events and Their Global Correlation, World and Regional Geology 10, Cambridge Univ. Press, (1997) 142. 41. V.I. Ustritskiy, Zoogeography of Late Paleozoic seas of the Siberia and Arctic area. Uchenye zapiski NIIGA. Paleontologiya i biostratigraphiya, 29 (1970) 58 (in Russian). 42. J.M. Dickins, What is Pangea? Canad. Soc. Petrol. Geol., Mem., 17 (1994) 67. 43. A.S. Dagys and A.M. Kazakov, Stratigraphiya, Litologiya i Tsiklichnost Triasovykh Otlozheniy Severa Srednei Sibiri. Nauka, Novosibirsk, 1984 (in Russian). 44. I.A. Dobruskina, Triassic flora. Trudy GIN SSSR, 208 (1970) 158 (in Russian). 45. V.A. Krassilov and Y.D. Zakharov, New finding of Pleuromeia in the Lower Triassic of Olenek River. Paleont. Zhum., 2 (1975) 133 (in Russian). 46. W.T. Holser, M. Magaritz and D.L. Clark, Carbon-isotope stratigraphic correlations in the Late Permian. Amer. J. Sci., 286 (1986) 390. 47. J.A. Alcala-Herrera, E.L. Grossman and S. Gartner, Nannofossils diversity and equitability and finefraction 813 C across the Cretaceous-Tertiary boundary at Walvis Ridge Leg 74, South Atlantic. Marine Micropaleontology, 20 (1992) 77. 48. F. Fabricius, H. Friedrichsen and V. Jacobshagen, Palaeotemperaturen und Palaeoklima in Obertrias und Lias der Alpen. Geol. Rundschau, 59 (1970) 805. 49. N.I. Kurushin and V.A. Zakharov, Climate of northern Siberia during Triassic. Bul. MOIP, Otd. Geol., 70, no. 3 (1995) 55. 50. A. Hallam, The earliest Triassic as an anoxic event, and its relationship to the end-Palaeozoic mass extinction. Canad. Soc. Petrol. Geol., Mem., 17 (1994) 797. 51. W.T. Holser, H.-P. Schoenlaub, M.Jr. Attrep et al., A unique geochemical record at the Permian/Triassic boundary. Nature, 337 (1989) 39.

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Persian-TriassicEvolutionof Tethysand WesternCircum-Pacific H. Yin, J.M. Dickins,G.R. Shi and J. Tong (Editors) 92000 ElsevierScienceB.V. All rightsreserved.

173

The Triassic of the Alps and Carpathians and its interregional correlation A. VOROS Geological and Paleontological Department, Hungarian Natural History Museum, Mflseum krt. 14-16, H- 1088 Budapest, Hungary

The Triassic stratigraphy and facies of the four major terranes of the Alpine-Carpathian region is shortly described and illustrated by schematic stratigraphic charts. The main stratigraphical features of the terranes are compared to those of the neighbouring epicontinental regions (Europe and North Africa) and the Aegean region, representing the Tethyan domain. The detailed ammonoid biostratigraphical subdivision developed in the Alpine region is also correlated with the neighbouring regions. The paleogeographical positions of the terranes are briefly discussed. It is concluded that the crustal fragments carrying the later Alpine-Carpathian terranes were in close connection with the Eurasian continental shelf in the Triassic, while during the Jurassic they belonged to different microcontinents within the western Tethys ocean.

1. INTRODUCTION The Alpine Trias has been the site of classical studies from the beginning of the geology and it is one of the best known part of the Triassic system world-wide. The pioneering works by G. Mtinster [1 ] and A. Klipstein [2] and the voluminous descriptions by F. Hauer, D. Stur, E. Suess, E. Mojsisovics and others made the Alps (and partly the Carpathians) one of the most important and renowned Triassic territories of the world [3] This region is still in the front of the scientific interest, because the selection of the stratotypes (GSSP) of the Ladinian and Carnian stages is just in course here, raising fruitful debates [4,5,6]. Therefore this chapter uses a great deal of classical knowledge, and was written as a compilation for the sake of completeness of the present IGCP Report. The Alpine-Carpathian Region (ACR) is here understood as a segment of the Alpine mountain system from the Western Alps to the Iron Gate (Southern Carpathians). Outcropping Triassic rocks are rather widespread in this region (Fig. 1). The ACR as an Alpine (Cretaceous to Tertiary) orogenic collage can be divided into four main terranes [7] (Fig. 2). The terrane concept and the paleogeographical aspects are discussed later. Adria. This is the largest terrane of the area frequently called the peri-Adriatic region, or Apulia, or Adriatic promontory. The northernmost part of this terr~ne is well-known as the Southern Alps of Italy. The eastern (Dinaric) and western (Apenninic) margins are strongly compressed into huge nappe systems and the southern, partly active, margin is concealed under the Mediterranean Sea. Alcapa. This is an elongate and structurally very complex, composite terrane, extending from the Western Alps (Sestri -Voltaggio line) to the Eastern Carpathians (Poiana Botizei). It

174 embraces the Briangonnais - Middle Penninic zones of the Alps and Carpathians, the Austroalpine nappes of the Eastern Alps, the extensive nappe pile of the Tatric, Fatric, Hronic, Gemeric (Silicic) units of the Inner West Carpathians and the Bfikk and Bakony units (Pelsonia partial terrane) in the intra-Carpathian region.

Germanic

Basin

1p s A

Gebze

k? Chios

Epidhavros + Hydra

500 i

U Israel, Neg

I~

1000 km ,,I

Figure 1. Outcrops of Triassic rocks (black) in the Alpine-Carpathian Region (framed) and its wider surroundings.

175

f

o

//C//I IIIIIIIIIIIIIIIIIIIIIIIIIII IIIIIIIIII

IIIIIIIIII V

J

~~

OE S I A

Figure 2. The major terranes of the Alpine-Carpathian Region (after Csontos et al.[7]) Tisia. This large terrane includes the Mecsek zone, the Vill~iny-Bihor zone and the superimposed Codru nappe system. The strike-slip faults and mobile zones bordering this suspect terrane are mostly buried by thick Tertiary sediments; consequently its limits are debated. Dacia. This elongate, S-shaped, composite terrane includes the inner East Carpathian Dacides, i.e. the Bucovinian nappe system with the superimposed Transylvanian exotic nappe outliers, and the Danubic and Getic units in the South Carpathians. In the present compilation the Triassic stratigraphy of the ACR will be summarised and demonstrated following the order of the above terrane subdivision.

2. TRIASSIC OF THE TERRANES OF THE ALPINE-CARPATHIAN REGION 2.1. Adria terrane

Only the northem margin of this terrane, the Southern Alps and a part of the Dinarides, belongs to the ACR. 2.1.1. Southern Alps The Southem Alps in northem Italy is the northernmost part of the Adria terrane. It represents the southern arm of the Alpine mountain chain, south of the Insubric (Periadriatic) Lineament. The whole range can be regarded as a huge block of Late Paleozoic - Mesozoic continental margin. Its Triassic stratigraphy is summarised here after the works [8, 9, 10, 11, 12, 13, 14, 15, 16]. The Triassic of the Southern Alps is underlain by extensive Upper Permian sequences showing an E-W trending paleogeographical polarity. The coarse-grained terrigenous clastics of the Verrucano Formation in the west (Lombardy) are followed by the Val Gardena

176 Sandstone eastward, then, in the Dolomites, the uppermost Permian is represented by the evaporitic, dolomitic Fiamazza facies and, even eastward, the marine Bellerophon Formation (Badiota facies) follows. After a short non-deposition, the Early Triassic transgression progressed westward: the shallow-marine carbonates pass into argillaceous beds (Lower Servino beds) toward Lombardy. The Scythian is represented by a sequence ranged into the Werfen Formation in the eastern and in the Servino Formation in the western parts. The subtidal-supratidal oolitic limestones, dolomites and marls form several depositional sequences, with maximum thickness (>800 m) in the east and gradually smaller thickness toward the west, where the mainly calcareous formations pass into the sandy/clayey Servino Formation. Marine faunal elements and biofacies characters of the Val Badia siltstones and marls show that the first true open-marine connections were established in the uppermost Scythian (Upper Olenekian). The Lower to Middle Triassic "Camiola di Bovegno", an evaporitic formation in Lombardy was deposited on shallow marine carbonate ramps bordering shallow basins with subtidal carbonate sedimentation (lower Angolo Limestone). On topographic highs in eastern Lombardy, shallow-water carbonate platforms were formed in the Anisian (Camorelli Limestone, Dosso dei Morti Limestone), with heteropic, deeper-water upper Angolo Limestone within the intervening basins. In the Late Anisian, pelagic conditions prevailed in eastern Lombardy (Prezzo Limestone), whereas in the West carbonate platforms developed (S. Salvatore Dolomite, Esino Limestone). Tectonic uplift and tilting of the previous platforms in the western Dolomites resulted in subaerial erosion and deposition of the Richthofen Conglomerate. Almost simultaneously, the first traces of volcanic activity appear ("pietra verde" tuffites). Afterwards, carbonate platforms developed in most part of the Dolomites (e.g. Contrin Limestone) but the accelerated and differential subsidence resulted in an intervening basin system which separated the platforms in the Ladinian (1000-1500 m of Sciliar Dolomite, Marmolata and Latemar Limestone). The major part of the Southern Alps was characterised by the deposition of siliceous, cherty pelagic limestones alternating with tuffites (Buchenstein i.e. Livinallongo Formation: 50-250 m), while the Salvatore and Esino platforms grew further through the Ladinian attaining 1000 m thickness. In the Late Ladinian, sedimentation was influenced by repeated tectonic movements and volcanism. In the Dolomites, the interplatform basins were filled with volcanoclastics and redeposited, platform-derived detritus (Wengen Group, Marmolada Conglomerate). Near the southerly lying volcanic centres, the growth of the platform was stopped, partly by emersion. In the Early Camian, after the end of the volcanism, new carbonate platforms evolved and prograded across the basins (Breno Fm. in Lombardy; Cassian and Diirrenstein Fm. in the Dolomites. In the Late Camian, a marked sea-level fall and the associated influx of siliciclastic material from the South, caused the extinction of most of the platforms. This "Raibl event" is represented by the sandy, marly Raibl beds in the Dolomites and by the upper part of the thick (up to 300 m) Val Sabbia Sandstones and the S. Giovanni Bianco evaporites in Lombardy. After the end-Camian filling of the previous basins, and the cessation of terrigenous influx, shallow-water, peritidal conditions have been established for the Norian and Rhaetian. Extensive masses of platform carbonates: the 1000-1500 m thick Dolomia Principale were formed. Despite the uniform lithology of these carbonates, thickness variations indicate

177 marked differences in the rate of subsidence. Due to normal faulting, local, anoxic basins developed in the Late Norian(Aralalta/Zorzino beds). These local basins were filled up by fine clastics (Riva di Solto shales) and carbonates (Zu Limestone) attaining 1000 m thickness, and peritidal conditions were re-established towards the end of the Rhaetian (Conchodon Dolomite). 2.1.2. Dinarides (Fig. 3) The Dinaric mountain chain is composed of four major elements [17]: Internal, or Vardar (Supradinaric), Dinaric, Budva (Epiadriatic), and Adriatic units. The whole Dinaric chain is affected by generally southwest vergent thrusts. The age of intense tectogenesis seems to shift from the innermost, northern sectors towards the outer, south-western ones. The stratigraphy of this unit is given according to [ 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29]. A D R I A (DINARIDES) Vardar

Supradinaric

RHAETIAN

.~

__

......

~ ~ ,

~I ~

CARNIAN .

~- .......

i'l

,-,-,,v ,~,.

~

~ . ~ 4. ~.

Dinaric

~'~-'~!

' ~

+

I

I

.

.............. ..""['T"::.'.'.--""

siliciclastics/coal

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deep water deposits

: l'

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influx

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neritic carbonates

l."k.~ k .~ki

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volcanites/pyroclastics calc-alkaline

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/pyroclastics

volcanites

Figure 3. Schematic stratigraphic chart of the Dinaric part of the Adria terrane. The stratigraphic columns were assembled according to their inferred palinspastic positions. Headings show the approximate location of the stratigraphic columns. The Dinarides show a quite uniform facies in the Late Paleozoic - Early Mesozoic. The weakly metamorphosed Early Paleozoic rocks are covered by marine carbonate and sometimes evaporitic Permian deposits in two places: in the coastal Velebit Mountains and in the Jadar block of Northern Serbia. The Lower Triassic clastic shallow marine sequences (350-500 m) rest unconformably on the Paleozoic. Higher up, in the Lower Triassic, 150-300 m thick, sandy, marly and dolomitic limestones and oolitic limestones became prevalent. The Anisian is dominated by a widespread carbonate platform environment almost everywhere. The Dinaric and Adriatic platforms Oust as the Durmitor, Drina-Ivanjica and Jadar platforms of the Supradinaric unit) tmderwent strong differentiation in the Anisian and at the beginning of the Ladinian. In some platform areas we can find condensed horizons, marked by the Han Bulog limestone (red, nodular limestone with ferromanganese crusts and with an extremely rich ammonoid fauna), in other places often with traces of subaerial erosion. This phase of emersion is followed by more or less intense calc-alkaline, then alkaline magmatic activity. These magmatites, which may attain the 200 m thickness, are often interfingering with the intraplatform basin sediments.

178 In the Adriatic area, the carbonate platform sedimentation was continuous from the Ladinian through the Triassic, until the early Tertiary. In the Budva zone a trough was opened due to Anisian tectonic events. Later on, it may have had ophiolitic basement, as indicated by the Ladinian pillow lavas found in the region. The facies of the Budva zone reflects the influence of the margins of the adjacent Adriatic and Dinaric carbonate platforms, supplying the material for the frequent breccias and allodapic limestone layers. The Middle-Upper Triassic sedimentation of the starved basin is characterised by very condensed pelagic carbonates, radiolarites and thin marly sequences, giving the matrix for the slope deposits. The Dinaric trait shows a typical facies pattern of an offshore carbonate platform. Medium to strong subsidence rates enabled the deposition of a very thick shallow marine sequence in the Middle and Late Triassic. The platform deposition is however interrupted by emersion event in the Ladinian-Carnian, indicated by formation of bauxites, but locally also by coarse clastics, or even coal deposits (Camian marls of Montenegro). The platform edges were generally formed of reefs, especially well developed in the Upper Triassic, the bulk of the carbonates is however consists of lagoonal limestones and dolomites. A very similar facies distribution characterises the Supradinaric unit (represented by the Durmitor and the Drina-Ivanjica elements). The clastic shallow marine Lower Triassic sequence consists of conglomerates, sandstones followed by laminated sandy micrites and massive, dark, "vermicular" limestones and may attain a thickness of 400 m. In the Middle Anisian the dark-grey micrites and dolomitized breccias are replaced laterally and upwards by light, thick-bedded, recrystallized platform limestones or by massive oncolitic light limestones: the Steinalm Formation (250 m). There are neptunian dykes in these shallowwater carbonates filled with the overlying rock: the thin horizon of the Han Bulog limestone (20 m). This grey to dark red, nodular micrite contains filaments, ammonites, Fe-Mn coatings, frequent hard-ground horizons. The condensed sequence is associated with the products of the Anisian-Ladinian volcanic activity. The magmatites and pelagic limestones are followed by thick shallow marine carbonates (Wetterstein limestones: 200 m). The bulk of the limestones and dolomites was deposited in intertidal lagoons but local reefs or oolitic shoals are also present. The Carnian emersion is also represented. In the rest of the Late Triassic, the platform sedimentation continued: thick masses of Dachstein Limestone (100300 m) were accumulated. Most of the Durmitor and Drina-Ivanjica blocks experienced normal faulting and subsidence in the Lower Jurassic, when their shallow-water sedimentation changed to a condensed pelagic one. 2.2. Alcapa terrane This terrane has a very complex structure with many nappes, tectonic windows and strikeslip-bounded units, some of which originated from very different paleogeographic position and were accreted during the Cretaceous to Tertiary Alpine orogeny. The Triassic stratigraphy of the Alcapa terrane will be presented in three segments: the Eastern Alps, the Inner West Carpathians and the Pelsonia partial terrane.

2.2.1. Eastem Alps This segment of the Alcapa terrane is bordered by the Rhenodanubian Flysch Zone on the north and the Insubric (Periadriatic) Lineament on the south. It is composed of two main

179 tectonic units: the lower, metamorphosed Penninic unit, appearing in tectonic windows, and the upper, Austroalpine units, which form a large system of nappes and occupies the major part of the Eastern Alps. The short summary of the Triassic of the Eastern Alps is based on the following works: [8, 30, 31, 32, 33, 34, 35, 36]. The medium-grade metamorphic Triassic rocks of the Penninic unit (Hochstegen facies) are known in the Tauern window. The sedimentary cover of the Variscan basement starts with Permian to Lower Triassic elastics, overlain by Middle Triassic dolomites and limestones. The Upper Triassic is represented by dolomites and chloritoid schists which may be the equivalents of the Germanic or Helvetic Keuper. The area of the future Austroalpine units was slowly invaded by the sea during Permian times from the SE, creating shallow marine successions with characteristic sandstone, evaporite and limestone facies (Gr6den, Haselgebirge and Bellerophon beds). At the beginning of the Triassic the whole area subsided below sea level, which is interpreted as the first sign of the later crustal thinning. The Lower Triassic shallow-water marine sandy shales and sandstones (Werfen beds) are followed in the Anisian by limestones (Reichenhall beds, Gutenstein Limestone) attaining 100 m thickness. In the Late Anisian, carbonate platforms evolved which produced more than 200 m thick sedimentary successions. The crustal stretching resulted in the formation of deep-water troughs between the platforms which became rather extensive at the end of the Anisian (Reifling limestones). A major basin was located to the south of the broad North Alpine carbonate platform and had a peculiar limestone facies, the variegated Hallstatt limestone. Its Anisian representative, the red, ammonitic limestone is called Schreyeralm Limestone. In the Ladinian, due to the accelerated subsidence, massive and very thick (1000-1700 m) platform carbonates (Wetterstein Limestone) have been accumulated. In the intervening basins, the deposition of the Reifling Limestones continued. Locally occurring thin layers of tuffites point to a distant volcanic source. During the Carnian, in contrast to the Middle Triassic situation, the sites of greatest sediment accumulation moved from the carbonate platforms to the intra-platform troughs. This Early Carnian change was triggered by a major drop of sea level. Moreover, climatic change to more humid conditions and relief rejuvenation due to tectonics in the continental background resulted in increasing terrigenous influence in the shelf. The terrigenous material transported from the north was trapped in a broad basin (Raibl basin). The platform to the south of this region shows almost no signs of this event. In the Norian the platforms prograded over the basins (except the Hallstatt basin) and a more or less uniform carbonate platform extended over most of the Austroalpine region (Hauptdolomit and Dachstein Limestone) attaining a thickness of 2000 m. Behind the 1000 m thick, massive Dachstein Reefs the extensive back-reef lagoons were sites of the cyclic sedimentation of the Dachstein Limestone. The typical rhythmic bedding of the thick limestone layers with Megalodontids and algal laminites was called Lofer facies and "Loferite", respectively [37]. During the Late Norian, in the area of the former Raibl Basin, a new basin was formed (K6ssen basin) showing also strong terrigenous influx (K6ssen beds). In the same time some parts of the platform margin were drowned and joined the epipelagic Hallstatt facies region in the south where the Zlambach beds were accumulated.

180

2.2.2. Inner West Carpathians (Fig. 4) This large segment of the Alcapa terrane comprises the true mountainous area of the West Carpathians in Slovakia. Its northern is formed by the arcuate, almost semi-circular northern fracture zone between the Pieniny Klippen Belt and the Outer Carpathian Flysch belt; the southern boundary follows the southern margin of the Veporic zone (Hurbanovo line, Lubenik line, etc.). The main tectonic units of the Inner West Carpathians, with significant Triassic sequences, are the Tatric, Fatric, Veporic, Hronic and Gemeric. They form an extensive nappe pile with the above order of superposition from bottom to top. This summary of Triassic stratigraphy was based mainly on the following works [38, 39, 40, 41, 42, 43, 44, 45,46,47,48]. A

Tatric

L

C

A

P

A (INNER

Fatric (Kri~na)

WEST

CARPATHIANS)

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Gemeric

RHAETIAN U

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~ NORIAN

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Figure 4. Schematic stratigraphic chart of the northern part of the Alcapa terrane from the Pieniny Klippen Belt (Poland) to NE Hungary. Same legend as in Figure 3. The Triassic sedimentary history of the Inner West Carpathians began with a widespread transgression in the Scythian. The basement was Permian in the Veporic and crystalline (mainly granitic) in the Tatric, supplying terrigenous detritus for the basal sequences. After the elimination of the relief, the terrigenous source disappeared and in the Anisian a purer carbonate sedimentation commenced (Gutenstein Limestone). The Middle Triassic was the time of extensive carbonate platform development (Steinalm Limestone in the Anisian, Wetterstein Limestone and Dolomite in the Ladinian). Differential subsidence of the individual crustal blocks caused differences in the thickness of the Middle Triassic carbonate platforms: thickest (500-800 m) in the south, medium in the Veporic and Fatric (200-500) and thinnest (100-200 m) in the north, in the Tatric, and led to the disintegration of the carbonate platforms in the southern zones. In the Gemeric shelf and in some units of the Hronic (Biely Vfih) pelagic basins have been formed in the Late Anisian characterised by the deposition of grey, nodular cherty limestones (Reifling beds) while in the southern, more pelagic areas, red, ammonitic, Schreyeralm or Han Bulog type limestones also occur. In these zones the pelagic basinal conditions persisted at least until the end of the Triassic. A little more to the north (Gemeric, Hronic) the carbonate platforms prograded slowly during the Ladinian and only smaller pelagic basins have remained for the end of the Middle Triassic. The Middle/Late Triassic boundary brought considerable changes in the evolution of the Inner West Carpathians. Passive subsidence continued on the southern shelf facing the Vardar ocean, but the northern (larger) domains followed a different tectono-sedimentary pattern. Instead of continuous and general subsidence, some crustal blocks were uplifted and tilted, and a series of half grabens were formed. In the early Carnian, the carbonate platforms were terminated by a strong terrigenous influx (Lunz beds). The south-western belt of the Tatric

181

became an elevated ridge at this time and retained this relative position until the end of the Jurassic. Asymmetrical half grabens, filled with detrital sediments ("Carpathian Keuper") were formed in the area of the Tatric and Fatric. These northern zones remained under the control of the terrigenous influx in the Late Triassic (though the Rhaetian KSssen-type facies of the Fatric points to a normal marine environment). The carbonate platforms have been withdrawn to the southern zones of the Hronic and the Gemeric but here they have developed in an enormous thickness (up to 800 m), proving that the crustal subsidence was the most intensive in this oceanward shelf margin. 2.2.3. Pelsonia (Fig. 5) This elongated partial terrane forms the south-eastem margin of the Alcapa terrane between the R~iba- Hurbanovo - Lubenik fault system in the north and the Mid-Hungarian Lineament in the south. It consists of the Bakony (Transdanubian Central Range) and Btikk units and the Meliata oceanic assemblage showing very close paleogeographical relationship to the Adria terrane and the Vardar (Supradinaric) units, respectively. The Triassic stratigraphy of Pelsonia is summarised after the following works: [43, 44, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61]. PELSONIA N Btikk

~

NORIAN

Central Btikk

_f-i

,

/_

S Btikk

~

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Bakony

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Figure 5. Schematic stratigraphic chart southern part of the Alcapa terrane (Pelsonia) from NE Hungary (Biikk Mts.) to the Transdanubian Central Range (Bakony). Same legend as in Figure 3. The scattered, allochthonous Alpine units within the Pannonian basin, can be considered as portions of a Late Paleozoic - Late Mesozoic continental margin. In their original setting these units formed a zone from passive margin to oceanic basement, from the Apulian platforms to the Vardar ocean. In a reconstructed pattern the Bakony unit lies in close vicinity of the Southern Alps, the Btikk unit near the north-eastern margin of the Dinaric unit, while the Meliata is best placed to the continuation of the Vardar zone. Prior to the Triassic, the whole region was a low-relief site of Late Permian terrestrial and shallow-water sedimentation. Red terrigenous sandstones of various grain-size are dominant up to or slightly above the Permian/Triassic boundary. In the eastern segments of the Bakony unit, shallow marine carbonate sedimentation with dolomites and oolitic limestone or evaporitic deposition appeared in the Late Permian. In the BiJkk unit, marine carbonates are

182

continuous across the Permian/Triassic boundary, with an intervening "boundary" clay and sandstone. In the lowermost Triassic slow transgression arrived from east-northeast to the area, resulting in marine conditions with various shallow-water limestones and local carbonate platforms in the Lower and Middle Anisian (Megyehegy Dolomite, Tagyon and Steinalm Limestones (100-200 m). This broad, more or less uniform continental shelf was fragmented by synsedimentary extensional tectonic movements from the Late Anisian onwards. While carbonate platforms persisted in some places, other areas became local basins filled with varied deeper water carbonates (Fels66rs Limestone). Crustal thinning and disintegration of the formerly uniform margin was the result of rifting marked also by traces of submarine volcanism starting around the Anisian~adinian boundary. The magrnatic activity was very significant in the Btikk, where Ladinian intermediate volcanics appear, while in the Meliata unit the rifting processes developed into an opening of a narrow basin with rift- or oceanic floor-related basalts, intrusives and ultramafics. After the Middle Triassic events a pattern of deeper basins with pelagic (commonly cherty) carbonates (Buchenstein Formation) and surviving platforms, with very thick peritidal carbonate sequences (Buda6rs Dolomite, Fennsik Limestone, 500-1000 m) were established. Intermediate regions became sites of volcano-detrital deposition (e.g. southern BiJkk areas). In the Carnian the significant "Raibl event" produced an influx of fine terrigenous clastic material (Veszpr6m Marl, up to 600 m thickness), which was partly the cause of the infill of many previous basins in these units. In Norian - Rhaetian times almost the whole segment of the peri-Adriatic margin was covered by shallow waters, and this led to the development of vast intertidal carbonate platform sequences with the exception of the Meliata unit and the probably adjacent marginal areas of the Bi.ikk, where Upper Triassic is represented partly with deeper water facies, passing continuously up to the Jurassic. In the Bakony unit, there are minor temporal differences in the appearance of the platform carbonates, however, the Hauptdolomit (Dolomia Principale) then Dachstein Limestone sedimentation was uniform. The 1500-2000 m thick platform carbonates indicate very rapid subsidence - a feature apparently general for the Mesozoic Tethys margins. In the western part of the Bakony unit, due to normal faulting in the Late Norian, local, partly anoxic basins developed and were filled up by redeposited platform-derived material (Rezi Dolomite), followed by fine clastics (K6ssen beds of up to 500 m thickness). In some parts, just as in the Austroalpine areas, the K6ssen beds overlie or interfinger with Dachstein Limestone. These intra-platform "K6ssen basins" were filled up and prograded by the Dachstein Limestone carbonate platform at the end of the Rhaetian.

2.3. Tisia terrane (Fig. 6) This roughly triangular terrane occupies the south-eastern half of the intra-Carpathian area. Its Mesozoic rocks appear on the surface only near the eastern and western terminations; the intervening part forms the basement of the Great Hungarian Plain and is covered by thick Tertiary sediments. The western and eastern terminations of this terrane are very vague; the northern boundary is the Mid-Hungarian Lineament whereas in the South a continuous, strongly folded belt of "Vardar elements" is thrust over the margin of the Tisia terrane proper.

183

The Tisia terrane can be subdivided into four tectono-sedimentary units. These are (from N to S): the Mecsek zone, the Vill~iny-Bihar zone, the Lower Codru Nappes and the Upper Codru + Biharia Nappes. Sources of data for the summary of the Triassic stratigraphy of the Tisia terrane are the following: [21, 49, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73]. T I S I A

Mecsek

....... ~l~

~

[--~

~

Vill~ny-Bihar

?+----- :-:: i-:.:-~- ~ _

Lower Codru

U p p e r Codru

~.~.-:-.-:-----.-. ~

".::':'--'" 9 : " - ' " ; i'-" "'-:'- ~ ~ ~ ~ ' " ~ : : ~ : ~

~

Halls

:

LADINIAN ANISlAN

"

"-: : : i v : - - - ' :

SCYTHIAN I " ": .':.'--;-'--':::

: . - : ---'.'.:.:: ".':: : : :. " " . - - : . ' . : : : . : : - . - : : :" "-'" :''.'.-'-"

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Figure 6. Schematic stratigraphic chart across the Tisia terrane from the Mecsek mountains (Hungary) to the Apuseni mountains (Romania). Same legend as in Figure 7. In the Tisia terrane, the Mesozoic sedimentary history starts with a very extensive and rapid transgression in the earliest Triassic. The basement, i.e. the peneplained land surface invaded by the sea, was made up by Permian sandstones, conglomerates and volcanites or locally (in the Southwest) by older metamorphic rocks. Correspondingly, the major part of the Scythian consists of conglomerates and thick (100-400 m) sandstones (Jakabhegy Sandstone). The lateral variations in thickness of this terrigenous complex may be due to an inherited basement topography. Diminution of grain-size and decrease of the amount of the terrigenous detritus gradually leads to the deposition of pure carbonate rocks ("vermicular" limestones) in the Anisian. Huge, up to 700 m thick carbonate platforms have developed in the south (Steinalm Limestone in the Upper Codru Nappes) while in the Villainy and Mecsek zones slightly deeper water but still shallow marine limestones predominate. The rapid shallow-water carbonate sedimentation keeping pace with the subsidence was interrupted by the widespread Late Anisian normal faulting which resulted in extensive basin formation. The deep water sedimentation lasted longer and the basins accumulated much thicker cherty limestones (Rosia Limestone, 300 m) in the south (Upper Codru Nappes); In the Bihor Autochthon more restricted and short-lived basins have been formed while the Mecsek-Vill~iny region remained seemingly unaffected. Here, in the north, the shallow-water carbonate sedimentation continued up to the end of the Ladinian and simultaneously the thick (100-300 m) "Wetterstein" platform prograded over the local basins in Bihor. The next important regional change in lithology can be recorded at the Ladinian/Carnian boundary when the sedimentation switched from carbonate to detrital in the Mecsek and Villainy. A southward tilting half graben has been developed in the Mecsek zone filled up with a very thick (600 m) Upper Triassic Keuper-type (sandstone/clay) sequence. At the same time, the neighbouring VillLqy zone suffered a differential uplift, erosion and on the rugged surface thin Keuper-type sediments accumulated in local basins. This terrigenous influx (implying an ultimate source in the European continent) appears in a weaker form (decreasing amount and grain-size of the terrigenous clastics) in the southern (Lower Codru) units.

184

During the Carnian and Norian the southward migration of the Keuper-type sedimentation seems to "push" forward the facies belt characterised by the carbonate platforms which in turn progrades over the pelagic basins. For the mid-Norian, this process was completed and was resulted in a typical "Alpine" facies pattern: Keuper-type sediments on the north (Mecsek, Bihar), "Hauptdolomit" in the middle (Lower Codru) and Dachstein Limestone in the south (Upper Codru). Local or wider (K6ssen-type) intra-platform basins enriched the paleogeographical picture in the Rhaetian. 2.4. D a c i a t e r r a n e (Fig. 7) This long, S-shaped terrane appears in the Romanian Eastern Carpathians and Southern Carpathians and in their continuation in Eastern Serbia and Bulgaria and is built up by a complex system of nappes. The great basement nappes are composed mainly by crystalline rocks, with subordinate Triassic sedimentary cover. In the East Carpathian segment, the Bucovinian nappe system is consists of the Infrabucovinian, Subbucovinian and Bucovinian nappes, with the uppermost, exotic Transylvanides. The South Carpathian segment is built up by the lower, Danubian and the upper, very extensive Getic and Supragetic nappes. The Triassic stratigraphy of the Romanian part of the Dacia terrane is summarised here mainly after the following works: [72, 74, 75, 76, 77, 78, 79]. DACIA

TRAN SYLVAN I O ES Olt ,

Per~ani

B U COVI N IAN Bucovinian s.s.

Subbucovinian

Infrabucovinian

, RHAETIAN .~

NORIAN

CARNIAN

ANISIAN SCYTHIAN

_
Hallstatt

~-r

,

_

:~

]

J

~ . ...

~ -

!

I !%

~ ;

-

-

~

-

-

.

-

9 : ....:.-

.. ............

. .......

,...

: "....

9 9 9 ........

. . . . . .

Figure 7. Schematic stratigraphic chart across the Dacia terrane of the East Carpathians (Romania). Same legend as in Figure 7. The basement of the Triassic sequences consists of Carboniferous clastics with coal seams and thick continental Permian in the Getic domain or thinner vestiges of these in the Bucovinian unit. The Lower Triassic, clastic, Werfen-type sediments rest tmconformably everywhere on this basement and are followed by dark dolomites and limestones of restricted carbonate platform facies (Gutenstein beds: 50-100 m). In the Anisian vast carbonate platforms developed, with up to 200 m thick dolomites. In the Ladinian, carbonate platform sedimentation continued in the Bucovinian trait but the majority of the previous carbonate platforms was subsided and pelagic (crinoidal, sometimes ammonitic) limestones and radiolarites were deposited in the Subbucovinian, Infrabucovinian and Getic units. The higher part of the Triassic is very poorly represented (except some Upper Triassic platform carbonates in the Bucovinian unit) due to a strong pre-Jurassic erosion which truncated the upper parts of the Triassic sequences and penetrated down to the Paleozoic in the Danubic and most of the Getic domains (Cimmerian orogeny ?). The Triassic of the Transylvanides (compiled from exotic nappes and olistolites) shows "Alpine" relationships. The Lower Triassic shallow marine clastic beds are followed by dark

185 carbonate sequences and thick platform carbonates (Steinalm Limestone) in the Anisian. Riftrelated magrnatites occurred first in the Late Anisian, but fully developed in the Ladinian. Parts of the former carbonate platform subsided at that time and pelagic, condensed Schreyeralm Limestones were deposited. In the Camian, the carbonate platform (Wettersteintype limestone of more than 100 m thickness) prograded over the pelagic realm, but soon drowned again and Hallstatt-type limestones were formed in most of the Late Triassic. In some blocks, the platform facies persisted through the Late Triassic, with formation of lagoonal and reefoidal Dachstein limestones and K6ssen-type intraplatform basin sediments.

3. INTERREGIONAL CORRELATIONS The terranes of the ACR are more or less foreign bodies in their present day geographic frame; their Mesozoic paleogeographic position and affiliation was the subject of several international paleogeographical projects [48, 80] and paleobiogeographical studies [81]. The reconstructions agree that the above mentioned terranes have been situated somewhere in the western Tethys in Triassic times. The Triassic facies and stratigraphy of the ACR will here be compared to those of the neighbouring epicontinental regions (Europe and Noah Africa) and the Aegean region, representing the "Western Tethys". 3.1. Facies and lithostratigraphy The strongly simplified stratigraphical schemes of the terranes of the ACR and the surrounding territories are shown in Fig. 8. The "Western Tethys" is exemplified by the Aegean region, notably the sequences described from Epidhavros [82], the islands of Hydra [83] and Chios [84, 85] and from Gebze (Northwest Turkey, [84]. The European epicontinental Triassic is represented by the sequence of the Germanic Basin [86, 87, 88]. The North African epicontinental sequence is shown by the example of Israel (Negev: [89, 90]. The stratigraphical schemes of the four terranes (Adria, Alcapa, Tisia, Dacia) were compiled after the literature cited in the respective chapters. The Triassic sequences start, almost uniformly, with transgressive, terrigenous clastics, except some parts of Adria and Alcapa, where the transgression commenced earlier, in the Permian. The Lower Triassic "Werfen beds", rather uniform in facies and thickness in the ACR, correspond more or less to the equivalent beds in the western Tethys, the Germanic Basin (Buntsandstein) and Israel (Yamin Fm.). Common feature is the onset of evaporitic sedimentation near the Scythian/Anisian boundary, as well, though this does not appear in the western Tethys and Israel. The Lower Anisian, mostly dark, sometimes vermicular, well bedded, neritic limestone (Gutenstein, Angolo, Wellenkalk, Raaf) is the last formation which shows more or less uniform facies all over the region. Strong differentiation started during the Anisian. In the western Tethys and the terranes of the ACR, due to tectonic disintegration, deep basins were formed and the remaining shallow regions kept their position as rapidly growing carbonate platforms; varied slope sedimentation prevailed in the transitional belts. In the epicontinental areas of Europe and North Africa the shallow marine, sometimes evaporitic, sedimentation continued up to the Late Triassic, with a low rate of subsidence.

186 The carbonate sedimentation (in platform/basin setting) continued during the rest of the Triassic in the western Tethys. On the other hand, in some parts of the terranes of the ACR, significant terrigenous clastic influx appeared from the Camian onwards. These "Raibl beds" are distributed on the western and northern facies belts of the respective terranes, suggesting a paleogeographic polarity and a common source area (parts of the European continent). In the major part of the terranes, the fine-grained clastic sediments became substituted by carbonate platforms (Hauptdolomite and Dachstein Lst.), attaining enormous thickness (2000 m) in the Norian and Rhaetian. However, in some northern belts of the Alcapa (Tatric of the West Carpathians) and Tisia (Mecsek and Villfiny zones) the terrigenous influx persisted or even increased in the Late Triassic ("Carpathian Keuper"). A comparable, local increase of clastic influx can be recorded in the Germanic Basin (e.g. massive sandstones of "Stubensandstein" and "Burgsandstein" in the "Steinmergelkeuper" sensu lato). A new phase of tectonic disintegration in the Late Norian resulted in the formation of intraplatform basins (Riva di Solto, K6ssen) in some parts of Adria, Alcapa and Tisia. In contrast to the previous, more or less continuous, passive subsidence, an end-Triassic uplift and strong erosion can be recorded in the Tisia and Dacia terranes. It is especially well manifested in Dacia (Getic and Danubic traits) where this pre-Jurassic erosion locally removed the whole Triassic and penetrated down to the Paleozoic basement. In summary, we may state, that the terranes of the ACR substantially show a western Tethyan sedimentary evolution in the Triassic, with a partial influence from the northern continent (Europe). The end-Triassic uplift and erosion in Tisia and especially in Dacia may suggest that these terranes have partly been affected by the "Cimmerian orogeny" [91 ].

3.2. Biostratigraphy The Triassic biostratigraphical correlation in and between the terranes of the ACR and the surrounding regions is extremely good as compared to the rest of the globe. The Triassic System was founded by F. von Alberti in the Germanic Basin, whereas the sections of the Alps, Balaton and Bosnia were the starting points of the Tethyan Triassic biostratigraphy. A great deal of classical and modem literature on the biostratigraphy of the ACR is available. There are some summarising works about the biostratigraphy of various fossil groups, e.g. sporomorphs and palynomorphs [92], calcareous algae [93, 94], radiolarians [95, 96], foraminifers [97, 98], pelagic bivalves [10], conodonts [82, 99, 100, 101, 102]. Ammonoid biostratigraphical correlation is shown in Fig. 9. By tradition and still in the present-day practice, ammonoids have a prime importance in Triassic biostratigraphy of the region. The standard Triassic biozones/chronozones have been named after ammonoid taxa and these are basic tools of the biostratigraphic correlation. The improvement of local biostratigraphical zonations is in continuous progress due to the recent samplings and investigations. Fig. 9 shows an updated scheme of the Triassic ammonoid zones and subzones of the terranes of the ACR, correlated with the "standard" Tethyan zonation and with the regional zones of Europe (Germanic Basin) and North Africa (Israel). The Tethyan zonation is applied from Krystyn (in Zapfe [103] with minor modifications. The Reitziites retzi Zone (sensu V6r6s et al. [5] is used here, instead of the Parakellnerites Zone and the Nevadites secedensis Zone (sensu Brack and Rieber [4] instead of the Nevadites Zone of Krystyn. The Trachyceras aon subzone is here raised to the rank of Zone (in fact, for technical reason, since it represents the Cordevolian Substage and a Substage has to

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188 correspond to at least one Zone). The positions of the Ladinian and the Camian Stages, in terms of ammonoid zones, are bitterly debated in the last years. The Subcommission on Triassic Stratigraphy will decide by voting on these questions. For the present compilation the base of the Ladinian was arbitrarily drawn at the Reitziites reitzi Zone and the base of the Camian at the Trachyceras aon Zone. The subzones (written in italics in Fig. 9) are taken from [107] for Alcapa, and mainly from [ 105] for Adria, except the Reitzi Zone for which the more detailed subzonal subdivision of Alcapa is shown. In the case of the Schreyerites binodosus Subzone, the generic assignment of the species binodosus and the seemingly contradictory correlation between Adria (Southern Alps) and Alcapa (Balaton Highland) given by Mietto and Manfrin [ 105] is here tentatively accepted. The ammonoid zonations of the individual terranes of the ACR and the compared regions are based on the following works: [5, 10, 104, 105, 106] for Adria; [5, 104, 107, 108, 109] for Alcapa; [66, 72] for Tisia; [72, 76, 110] for Dacia; [86, 111 ] for the Germanic Basin and [90] for Israel. There is no record of ammonoid zones in the Lower Triassic of the ACR and surrounding regions, except the Tirolites cassianus Zone in Adria and Alcapa. The Middle Triassic ammonoid zonation is extremely detailed. In Adria (Southern Alps) and Alcapa (Northern Calcareous Alps, Balaton) the standard zones have been subdivided into subzones and their correlation between the terranes is also excellent. Some of the standard zones have been proved also in Tisia and Dacia. The ammonoid zonations of the Germanic Basin and Israel show very little in common with that of the ACR. The Lower Anisian Beneckeia tenuis and B. buchi zones seems to occur in the Bulgarian part of Dacia. Widespread correlation is possible in the Pelsonian by the Balatonites balatonicus Zone which is proved everywhere, except Tisia. The Illyrian Paraceratites trinodosus Zone is also very widespread and can be correlated by closely related forms in the Germanic Basin and Israel. In the Ladinian, the Germanic ammonoid faunas became strongly endemic and an indigenous, very detailed local zonation has been developed for the Upper Muschelkalk. The only trace of correlation seems to be the alleged occurrence of the Opheoceratites evolutus zone in Dacia (Bulgarian part: [110]). Israel belonged to the Sephardic bioprovince, this explains its local ammonoid zonation. Yet, this fauna had some connection with the Tethyan one and this permits direct correlation in certain horizons (e.g. Eoprotrachyceras curionii and Protrachyceras archelaus Zones). The Late Triassic extension of carbonate platforms and Keuper-type sedimentation in the majority of the terranes of the ACR and the surrounding regions was tmfavourable for ammonoids. Therefore, detailed ammonoid zonation has been developed only in the Hallstatt zone of Alcapa. Some of the standard zones (Trachyceras aon Z., Tropites subbullatus Z.) have been proved in the Hallstatt facies of the highest tectonic units of Tisia (Upper Codru Nappes) and Dacia (Transylvanides).

3.3 Paleogeography: microplates and terranes in the ACR A detailed paleogeographic (plate-tectonic) reconstruction is much beyond the scope of the present paper. However, since a review of the Triassic paleogeography is needed and since the terms "microplate" and "terrane" are often used, it is important to make a clear distinction between the two concepts for the present paper and for the time period and area concemed.

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Tethyan Ammonoid Zones

ADRIA

ALCAPA

~outhern Alps, Dinarides

North. Calc. Alps, West Carpathians, Pelsonia

(after Krystyn in Zapfe 1983)

Rhaetian

Choristoceras marshi Rhabdoeeras suessi Halorites macer Himavatites hogarti Cyrtopleurites bicrenatus Juvavites magnus Malayites paulckei Guembelites jandianus ."Anatropites" Tropites subbullatus Tropites dilleri Austrotrachyceras austriacum Trachyceras aonoides Trach~,ceras aon Frankites regoledanus

Sevatian Alaunian

.acian Tuvalian

7 Y" Julian Cordevolian

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Protrachyceras archelaus

.

Z <_

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i

Eoprotrachyeeras eurionii Nevadites secedensis Fassanian Reitziites reitzi

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Paraceratites trinodosus

~elsonian

Balatonites balatonicus

Bithynian

Aghdarbandites ismidicus Ag Nicomedites osmani Ae~eiceras u~ra Keyserlingites subrobustus Tozericeras pakistanum Tirolites cassianus Wasatchites tardus Meekoceras gracilitatis Flemingites rohilla Gyronites frequeus Ophicerls connectens

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I |

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Israel, Negev

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T. cassianus

A. T. T. F.

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r. subbullatus

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r. aon

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?rotrachyceras sirenitiforme ?rotrachyceras hispanicum ?rotrachyceras ladinum amplum

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T. cassianus

t ~ ' ~ I ~* |

Figure 9. Interregional correlation of the Triassic ammonoid zones and subzones (italics) of the terranes of the ACR with the "standard" Tethyan zonation and with the regional zones of Europe (Germanic Basin) and North Africa (Israel).

190 Microplate is a plate-tectonic term and it means any smaller lithospheric plate, irrespective of the nature of the crust. Oceanic microplates are usually consumed completely. Other microplates carry pieces of continental crust. These smaller or larger areas with continental crust can be termed as microcontinents or continental fragments. During and aider the collisional phases the accreted and deformed continental fragments are called terranes. Terranes are the elementary particles of the huge tectonic collages of the orogenic belts. Following the improved American definition [112] terranes are defined by an internally consistent stratigraphy and paleogeography and are bounded by large-scale faults, trench complexes or other zones representing telescoped oceanic lithosphere. Exotic terranes have distinct geological record unique to each terrane and different from that of the neighbouring continent; proximal terranes may have similar geological record and may only be distinguished by the presence of peculiar terrane boundaries. The ACR consists of numerous tectonic units bordered mainly by strike-slip faults and/or thrust faults and fossil subduction zones. Their paleogeographical setting is uncertain with respect to cratonic Europe therefore the term terrane seemed appropriate for them [ 113, 114]. In the last years an array of papers appeared on the terrane analysis of the European Alpides from the Western Alps [ 115] to the Dinarides [ 116] and Hellenides [ 117]. It is seen from these papers that the authors developed extremely detailed terrane subdivisions (almost 30 terranes) for the area concerned. This number is obviously too high for a review article, therefore the more simplified terrane classification [7] was used in the present paper (Adria, Alcapa, Tisia, Dacia). In fact, these are composite terranes, i.e. they contain juxta- or superimposed tectonic elements of different paleogeographic origin. This is the most evident in the case of the Alcapa terrane which was divided into seven terranes by the present author [81 ] and into sixteen by later workers [ 115, 118, 119]. The Triassic (and later Mesozoic) paleogeographic positions of the terranes and their components are widely and strongly debated. This was the subject of several international paleogeographical projects [48, 80], research papers [43, 120, 121] and paleobiogeographical studies [81 ]. Some of these plate tectonic syntheses suggested that in the Early Mesozoic their microcontinents were closely attached to the European and/or the African craton. Others favoured the concept of an intra-Tethyan microcontinents isolated from the European and African shelves, named as "Kreios" [122], "Mediterranean microcontinent" [123, 124], "Adriatic microplate" [ 125], "Apulia-Anatolide" block of the Cimmerian continent [91 ]. As a good compromise between these opposing views, the recent reconstruction by Stampfli and Marchant [126] is used here to illustrate the supposed paleogeographic positions of the microplates carrying the terranes of the ACR (Fig. 10). The Late Triassic paleogeographic picture shows the trifurcate western end of the Tethys ocean penetrating between the African and Eurasian parts of Pangea. The southern (East Mediterranean) and northern (Vardar-Meliata) arms are remnants of the Paleotethys while the central arm is the newly opening Pindos ocean. The later terranes of the ACR are in coherent connection with the European craton; the gradual transition of facies from the Germanic Keuper to the Alpine Hallstatt basin recorded in the Alpine, Carpathian and Tisia traverses seems to prove this. Adria and Pelsonia are in more distal position, whereas Dacia is envisaged as part of the Cimmeride orogen [91 ].

191 In the Jurassic an arm of the Central Atlantic rift system reached the area. By this rifting several microcontinents have been detached from the Eurasian shelf. First the Mediterranean microcontinent (embracing Adria, the Pelagonian and Hellenic-Turkish blocks) at about the Triassic/Jurassic boundary), then the Austroalpine-Carpathian microcontinent drifted apart, successively. In a next step, the opening of the Valais rift split apart the Iberian microcontinent carrying the Briangonnais - Middle Penninic belt as a northern prong. An incipient rifting removed Tisia and Dacia from Eurasia. T!

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Figure 10. Reconstruction of the western Tethyan area for Late Triassic and Late Jurassic times, showing the supposed positions of the terranes discussed in the paper. Redrawn after Stampfli and Marchant [ 126], modified for Tisia and Dacia. Vertically ruled: main continents and shelves, cross-ruled." microcontinents. Elements of the Alcapa composite terrane: 1: Briangonnais-Central Penninic, 2: Austroalpine units, 3: Inner West Carpathians, 4: Pelsonia. Note that in the Triassic the terranes belonged to the wide and dissected Eurasian shelves, whereas in the Jurassic they drifted away as parts of different microcontinents. It is seen that the elements of the Alcapa composite terrane belonged to different paleogeographic domains in the Triassic and moved separately, as parts of different microcontinents in the Jurassic. In the course of the Alpine orogeny (Cretaceous to Tertiary) the intervening oceanic belts were consumed, the microcontinents were collided and some of their crustal elements were sheared off and formed huge nappes. In spite of the extremely intricate structure of the Alcapa composite terrane, its elements may be termed as proximal terranes because, after a short excursion, they joined their mother continent (except Pelsonia which originated from the Mediterranean microcontinent). The other three terranes studied (Adria, Tisia, Dacia) also suffered severe deformation during the Alpine collision but they represent more or less the same paleogeography what they had as Early Mesozoic microcontinents. From among them, Tisia may be termed as proximal terrane because its mother continent and host continent seems to be the same

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(Eurasia). The other two, perhaps, can be considered to be exotic or suspect terranes. Dacia, if its allocation as part of the Cimmerian continent is accepted, may be regarded as a Gondwanian fragment. Adria, as part o f the Mediterranean microcontinent, was certainly detached from the African craton by the East Mediterranean rifting, whereas its Early Mesozoic continuity towards the Eurasian continent does not seem so evident. 4. A C K N O W L E D G E M E N T S The author is indebted to Prof. Yin Hongfu (Wuhan, China), the leader o f IGCP Project 359 for the support and invitation to contribute to the present volume. Thanks are due to Prof. M. Gaetani (Milano) and to an anonymous reviewer for critically reading the manuscript. The work was partly supported by the National Scientific Research Fund of Hungary (OTKA, project number T 026278). REFERENCES 1. G. G. Miinster, 0ber die Kalkmergel-Lager von St. Cassian in Tyrol und die darin vorkommende Ceratiten. N. Jb. Miner. Geogn. Petrefactenk. (1834) 1-15. 2. A. Klipstein, Mittheilungen aus dem Gebiete der Geologic trod Palaeontologie. Mittheilungen aus dem Gebiete der Geologic und Palaeontologie. Giessen, 1843. 3. E. T. Tozer, The Trias and its ammonoids: the evolution of a time scale. Geological Survey of Canada, Miscellaneous Report, 35 (1984) 1-171. 4. P. Brack and H. Rieber, The Anisian/Ladinian boundary: retrospective and new constraints. Albertiana, 13 (1994) 25-36. 5. A. VSr/Ss, I. Szab6, S. Kov~ics, L. Doszt~ily and T. Budai, The Fels68rs section: a possible stratotype for the base of the Ladinian stage. Albertiana, 17 (1996) 25-40. 6. C. Broglio Loriga, S. Cirilli, V. De Zanche, D. di Bad, P. Gianolla, G. F. Laghi, W. Lowrie, S. Manfrin, A. Mastandrea, P. Mietto, G. Muttoni, C. Neff, R. Posenato, M. Rechichi, R. Rettori and G. Roghi, A GSSP candidate for the Ladinian/Carnian boundary: the Prati di Stuores/Stuores Wiesen section (Dolomites, Italy). Albertiana, 21 (1998) 2-18. 7. L. Csontos, A. Nagymarosy, F. Horvfith and M. Kovfi(,, M., Tertiary evolution of the Intra-Carpathian area: a model. Yectonophysics, 208 (1992) 221-241. 8. T. Bechst~idt, Z. Brandner, H. Mostler and K. Schmidt, Aborted riffing in the Triassic of the Eastern and Southern Alps. N. Jb. Geol. Pal., Abh., 156 (2) (1978) 157-178. 9. G. Bertotti, V. Picotti, D. Bernoulli and A. Castelladn, From rifting to drifting: tectonic evolution of the South-Alpine upper crust from the Triassic to the Early Cretaceous. Sed. Geol., 86 (1993) 53-76. 10. P. Brack and H. Rieber, Towards a better definition of the Anisian/Ladinian boundary: New biostratigraphic data and correlations of boundary sections from the Southern Alps. Eel. Geol. Helv., 86 (2) (1993) 415-527. 11. C. Broglio Loriga, F. G6czfin, J. Haas, K. Lenner, C. Neff, A. Oravecz-Scheffer, R. Posenato, I. Szab6 and A. Y6th-Makk, The Lower Triassic of the Dolomites (Italy) and Transdanubian Mid Mountains (Hungary) and their correlation. Mem. Sci. Geol., 42 (1990) 61-133. 12. V. De Zanche, P. Gianolla, P. Mietto and C. Siorpaes, Triassic sequence stratigraphy in the Dolomites (Italy). Mem. Sci. Geol., 45 (1993) 1-27. 13. M. Gaetani, M. (ed.), Field Guide-book, R. Assereto and G. Pisa Field Symposium on Triassic Stratigraphy in Southern Alps. Bergamo, 1979. 14. M. Gaetani, M. Gnaccolini, F. Jadoul and E. Garzanti, Multiorder sequence stratigraphy in the Triassic System of the western Southern Alps. In: Mesozoic and Cenozoic Sequence Stratigraphy of European Basins, SEPM Spec. Publ., 60, 1998. 15. M. Gnaccolini and F. Jadoul, Carbonate platform, lagoon and delta "high frequency" cycles from the Camian of Lombardy (Southern Alps, Italy). Sedim. Geol., 67 (1990) 143-159.

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101. S. Kov~ics, A. Nicora, I. Szab6 and M. Balini, Conodont biostratigraphy of Anisian/Ladinian boundary sections in the Balaton Upland (Hungary) and in the Southern Alps (Italy). Courier Forsch.-Inst. Senckenberg., 118 (1990) 171-195. 102. K. Budurov, Conodont stratigraphy of the Balkanide Triassic. Riv. Ital. Paleont., 85 (1980) 767-780. 103. H. Zapfe, Das Forschungsprojekt "Triassic of the Tethys Realm" (IGCP Proj. 4) Abslussbericht. Schriflenr. erdwiss. Komm./5stem Akad. Wiss., 5 (1983) 7-16. 104. R. Posenato, Tirolites (Ammonoidea) from the Dolomites, Bakony and Dalmatia: Taxonomy and biostratigraphy. Ecl. Geol. Helv., 85 (1992) 893-929. 105. P. Mietto and S. Manfifn, A high resolution Middle Triassic ammonoid standard scale in the Tethys Realm. A preliminary report. Bull. Soc. g6ol. Fr., 166 (5) (1995) 539-563. 106. M. Urlichs, Trachyceras Laube 1869 (Ammonoidea) aus dem Unterkam (Obertrias) der Dolomiten (Italien). Stuttgart. Beitr. Naturk. (B) 217 (1994) 1-55. 107. A. V/Sr/$s, A Balaton-felvid6k tri~sz ammonoide~ii 6s biosztratigr~fi~ija (Triassic ammonoids and biostratigraphy of the Balaton Highland). Studia Naturalia, 12 (1998) 1-104. In Hungarian with Engl. abstr.) 108. L. Krystyn, Zur Ammoniten- und Conodonten-Stratigraphie der Hallst~itter Obertrias (Salzkammergut, 0sterreich). Verh. geol. Bundesanst. (1973) 113-153. 109. L. Krystyn, Eine neue Zonengliederung im alpin-mediterrane Unterkam. Schriftenr. erdwiss. Komm. 6sterr. Akad. Wiss., 4 (1978) 37-75. 110. D. A. Tronkov, Triassische Ammoniten-Sukzessionen im westlichen Balkangebirge in Bulgarien. C. R. Acad. Bulg. Sci., 29 (9) (1976) 1325-1328. 111. M. Urlichs and R. Mundlos, Revision der Gattung Ceratites de Haan 1825 (Ammonoidea, Mitteltrias). I. Stuttgart. Beitr. Naturk., (B) 128 (1987) 1-36. 112. D. G. Howell, Tectonics of Suspect Terranes. In: Mountain building and continental growth. Topics in the Earth Sciences No. 3. Chapman and Hall, London, New York, 1989. 113. A V6r6s,. Conclusions on Brachiopoda. In: M. Rakus, J. Dercourt and A. E. M. Nairn (Editors), Evolution of the Northern Margin of Tethys. I. M6m. Soc. G6ol. France, Paris, N. S., 154 (1988) 79-83. 114. W. B. Hamilton,. On terrane analysis. Philos Trans. Roy. Soc. London A, 331 (1990) 511-522. 115. F. Neubauer, F. Ebner, W. Frisch and F. P. Sassi, Terranes and tectonostratigraphic units in the Alps. In: Papanikolau, D. (ed.): IGCP Project No 276. Terrane maps and terrane descriptions. Ann. G6ol. Pays Hell6n., 37 (1996-97):219-243. 116. S. Karamata and B. Krsti6,. Terranes of Serbia and neighbouring areas. In: Kne~evi6, V. and Krsti6, B. (eds): Terranes of Serbia, Belgrade, 1996. 117. D. J Papanikolau, The tectonostratigraphic terranes of the Hellenides. In: Papanikolau, D. (ed.): IGCP Project No 276. Terrane maps and terrane descriptions. Ann. G6ol. Pays Hell6n., 37 (1996-97): 495-514. 118. A. Vozfirov~i and J. VozAr, Terranes of the West Carpathian-North Pannonian domain. In: Papanikolau, D. (ed.): IGCP Project No 276. Terrane maps and terrane descriptions. Ann. G6ol. Pays Hell6n., 37 (1996-97): 245-269. 119. S. Kov~ics, T. Szederk6nyi, P./krkai, Gy. Buda, Gy. Lelkes-Felv~iri and A. Nagymarosy, Explanation to the terrane map of Hungary. In: Papanikolau, D. (ed.): IGCP Project No 276. Terrane maps and terrane descriptions. Ann. G6ol. Pays Hell6n., 37 (1996-97): 271-330. 120. S. Kov~ics, Tethys "western ends" during the Late Paleozoic and Triassic and their possible genetic relationships. Acta Geol. Hung., 35 (4) (1992) 329-369. 121. J. Haas, S. Kovfics, L. Krystyn and R. Lein, Significance of Late Permian- Triassic facies zones in terrane reconstructions in the Alpine-North Pannonian domain. Tectonophysics, 242 (1) (1995) 19-40. 122. A. Tollmann, Plattentektonische Fragen in den Ostalpen und der plattentektonische Mechanismus in mediterranen Orogens. Mitt. 0sterr. Geol. Ges., 69 (1976) 291-351. 123. A. V6rSs, Provinciality of the Mediterranean Lower Jurassic brachiopod fauna: causes and plate tectonic implications. Palaeogeogr., Palaeoclimatol., Palaeoecol., 21 (1) (1977) 1-16. 124. A. V/$r~s, Lower and Middle Jurassic brachiopod provinces in the Western Tethys. F/51dt. K/Szl. Budapest, 110 (3-4) (1980) 395-416. 125. D. V. Ager,. The geology of Europe. McGraw-Hill, 1980. 126. G. M. Stampfli and R. H. Marchant, Geodynamic evolution of the Tethyan margins of the Western Alps. In: A. O. Pfiffner (ed.): Deep structure of the Swiss Alps. Birkh~iuser, Basel, Boston, Berlin, 1997.

Persian-Triassic Evolutionof Tethys and WesternCircum-Pacific H. Yin, J.M. Dickins, G.R. Shi and J. Tong (Editors) 92000 ElsevierScience B.V. All rights reserved.

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The Triassic of China and its interregional correlation* Hongfu YIN and Yuanqiao PENG Faculty of Earth Sciences, China University of Geosciences, Wuhan, Hubei, China, 430074

The Triassic of China can be subdivided into six regions, namely, the cool temperate North Asia (scarce deposits) and Boreal Sea (no definite deposits), the warm temperate Central Asia (terrestrial) and NW Pacific (marine), the tropical Cathayian Tethys, the warm temperatetropical Gondwanan Tethys (the Himalayas and Yarlung Zangbo belt). The Cathaysian Tethys is further subdivided into Tibet-Qinghai and South China subregions, in which Triassic deposits are the best exposed and investigated. Stratigraphic sequences of representative areas are indicated, and summarized into synthetic chart with different fossil zonations. Correlation with adjacent areas is briefly discussed. Triassic strata constitute a 2 "d order sequence set with a remarkable two-fold character (four 2 nd order sequences) and twelve 3 rd order sequences. Influence of the Indosinian Orogeny on the Triassic sequences and their distribution is emphasized.

INTRODUCTION Based on the geotectonic background, stratigraphic and sedimentary characteristics and palaeo-biogeographical provincialization [ 1-4], the Triassic System of China is represented by six geographic regions categorized into four realms (Fig. 1). 1.North Asia and Boreal Sea Regions of North Laurasia Realm (Fig. 1, Ii-I2) 2.Central Asia and NW Pacific Regions of Central Laurasian Realm (Fig. 1, II~-II2) These two realms belonged respectively to the cool-temperate and warm-temperate zones [ 1], thus yielding different sediments and biota. Tectonically, both North and Central Regions are located within the Eurasian Plate, and are characterized by accumulations in continental intermontane basins and large-scale fluvio-lacustrine basins, associated with volcanism. The Central Asia Region includes the area lying to the north of the Kunlun, Qinling and Dabie mountains. It also yields short-term transgressions along the southern margin, such as South Qilian. The biota comprises the Danaeopsis fecunda-Bernoullia (Symopteris) zeilleri (abbreviated as D.-B.) flora and freshwater animals, reflecting a warm-temperate and relatively dry climate. 3. Cathaysian Tethys Region of the Eurasian Tethys Realm (Fig. 1, III~-III2) In the Triassic this region occupied the Eurasian part of the Tethys, basically representing a vast archipelagic ocean, comprised of scattered microplates and micro-oceanic basins, rifted blocks and seaways, as well as island arcs and troughs [5]. Therefore, the deposits represent

* This work is supported by the National Natural Science Foundation of China Project, No: 49632070.

198 both marine active margin and platform environments. The biota all belonged to the tropic Tethyan type, with high diversity and endemism, reflecting a humid tropical climate. In this part, the South China Region has been studied in great detail. 4. Eastern Gondwanan Tethys Realm (Fig. 1, IV) It includes the margin of the Gondwanaland submerged by the Tethys Ocean which yields platform deposits, as well as the abyssal and oceanic deposits along the suture between the Eurasia and the Gondwana. The biota belongs to the Gondwanan Tethys region, reflecting a non-tropical climate. This region includes the Himalayas and its southeastern extension in Yunnan--the Tengchong area.

1. TRIASSIC OF NORTH ASIA AND BOREAL SEA REGIONS 1.1. Triassic of Boreal Sea Region (Fig. 1, I~) Theoretically the northernmost area of Heilongjiang Province belonged to its MongoliaOkhotsk Subregion, which was characterized by marine clastic deposits of the Lower and Upper Triassic series on the Russian side. However, there are no definite reports as yet of comparable Triassic deposits within the border of China. 1.2. Triassic of the North Asia Region (Fig.l, I2) The Triassic of the North Asia Region is known from only 3 localities. It differs from the Central Asia Region in that it generally comprises intermontane basin deposits. Its organisms belong to the boreal (temperate) Maltsev Fauna (with the typical assemblage found in the Kuznets Basin of Central Asia). The Late Triassic is characterized by pure Danaeopsis fecunda-Bernoullia (Symopteris) zeilleri assemblage (abbreviated as D.-B.) Flora, i.e., not mixed with any elements of the Dictyophyllum nathorsti-Clathropterismeniscioides (abbreviated as D.-C.) Flora.

2. TRIASSIC OF CENTRAL ASIA AND NW PACIFIC REGIONS 2.1. Triassic of NW Pacific Region (Fig.l, 112) Tectonically this region belonged to the pre-Pacific continental margin of the Eurasian plate, and to the active convergent Pacific oceanic plate margin. The biota reflected a warm temperate and humid climate. In China it may be divided into: (1) Sikhote-Subregion, Fig. 1 Stratigraphic provincialization of the Triassic System of China (emended from [3]) Area with solid black, Triassic outcrops; area with lines, Triassic and Jurassic undivided; I1 Boreal Sea Region and; I2 North Asia Region; II1 Central Asia Region; II11 North China; II12 North Qilian-Hexi corridor-Beishan; II13 Yanshan and southern Northeast China; II14North Tianshan and Junggar; II15 South Tianshan; II 21 South Qilian; III Cathaysian Tethys Region; III, l Gangdise-Nyainqentanglha-Baoshan block; IIIl 2 Bangong Co-Nujiang Folded Belt; III13 Karakorum-Qiangtang-Tanggula-Qamdo--Lanping-Simao Block; III a Bayan Har-SongpanGarze Folded Belt; III~5Qinling Folded Belt; III21Yangtze Platform, III22Cathaysia Platform; III23 Youjiang Folded Belt; Eastern Gondwanan Tethys Region; 1Vl Himalayas Platform Margin; IV2Yarlung Zangbo and Indus Folded Belt

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200 including parts of Jilin and Heilongjiang Provinces along the Sino-Russian border. Only the Upper Triassic series is represented by continental volcano-sedimentary formations, that contain the hydrothermal D.-C. Flora [6]. (2) Taiwan: so far only an undetermined Triassic age of rocks has been reported there.

2.2. Triassic of the Central Asia Region (Text-fig.l, II 0 2.2.1. North China (Fig.l, Ill ~) The bulk of North China was a huge Triassic depositional basin, within which the Shaanxi-Gansu-Ningxia basin has been studied in great detail. Its stratigraphic sequence is recognized as follows [7]. Lower Jurassic Fuxian Formation disconformity 5. Late Triassic Yanchang Group. Lacustrine deposits including greyish green to yellowish green fine sandstone, slitstone and mudstone. The lower part contains more sandstone; the middle part contains fine sandstone interbedded with siltstone and mudstone, while the upper part is dominated by siltstone and mudstone, and contains coal seams or coal streaks. Together with the Tongchuan Formation it constitutes a 2 no order sequence. It yields the well-known Yanchang Flora with more than 100 known species of 38 genera, which represent the Danaeopsis fecunda-Bernoullia (Symopteris) zeilleri-Thinnfeldia (D.-B.) Flora. The assemblage has rare cycadophyta and lacks Dipteridaceae, but contains other elements of the D.-C. Flora, such as Lepidopteris ottonis, Nilsonia acuminata and the genera Ptilozamites, Anomozamites, Pterophyllum, etc. The sporopollens are represented by the Dictyophyllidites-Apiculatisporis-Lueckisporites triassicus assemblage, while the bivalves are characterized by abundant Shaanxiconcha, Sibireconcha and relatively numerous Unio. In addition, there are also pisces (Triassodus), abundant conchostracans and ostracods. Chronological analyses of the different groups all point to Late Triassic. >410-1,000m 4. Late Middle Triassic Tongchuan Formation. It includes a coarser lower member, dominated by sandstone, and a finer upper member, composed of interbedded fine sandstone, siltstone and shale intercalated with many oil shale layers. It yields more than 30 species of plants, which are characterized by Tongchuanophyllum, Danaeopsis magnofolia, D. marantacea, Annalepis and the large-sized Equisetites and Neocalamites, together with Pleuromeia. Based on analysis of the flora, its age is Middle Triassic. The sporopollen assemblage is similar to that of the Ermaying Formation, while the bivalves are characterized by the Unio-Shaanxiconcha longa group, but no definite Sibireconcha has been found, indicating an age probably older than the Yanchang Group. The conchostracans and ostracods are similar to those of the Yanchang Group. In addition, there are also the pisces Hybodus youngi and the plesiosauridae. 100-596m 3. Early Middle Triassic Ermaying Formation. It is composed of greyish white, yellowish green and yellowish pink quartzose arkose in the lower member and dominated by purple silty mudstone, containing calcareous and gypsum nodules in the upper member. This formation abounds in the Sinokannemeyeria Fauna, with Sinokannemeyeria, Parakannemeyeria, Shansisuchus, Sinognathus and Shansiodon in the upper member and Paoteodon, Ordosiodon, Ordosia, Shanbeikannemeyeria and Parakanne-meyria in the lower member. The plants include Protoblechnum wongii, Bernoullia (Symopteris) cf.

201

zeillerL Aipteris wuziwanensis, Todites shensiensis, Annalepis sp., Pleuromeia wuziwanensis and Voltzia walchiaeformis, while the sporopollen is represented by the Punctatisporites-Chordasporites-Plicatipollenites assemblage. Based on comprehensive analysis of fossil vertebrates, plants and other groups, this formation is of Early Middle Triassic age. 416-700m 2. Late Early Triassic Heshanggou Formation. It is composed of purplish red sandy mudstone interbedded with fine arkose sandstone. The fossils include the plants Pleuromeia sternbergi, P. rossica, Yuccites? sp., Voltzia sp., Neocalamites sp., Equisetites sp.,Neuropteridium sp. and Anomopteris mougeoti, the sporopollen VerrucosisporitesLundbladispora-Taeniaesporites assemblage, the vertebrates Fugusuchus hejianensis, Procolophonidae, Benthosuchidae, Ceratodus heshanggouensis and Ordosia, together with 4 species of the ostracod Darwinula. The vertebrates correspond to the Olenekian Fuguan stage of Lucas (1998) and plants to the Early Triassic-Anisian Pleuromeia-Voltzia Flora. 103-280m 1.Early Early Triassic Liujiagou Formation. Greyish purple arkose in the lower part, and greyish purple feldspathic silicarenite interbedded with siltstone in the upper part. The fossil plants include Pleuromeia rossica, P. jiaochenensis, Crematopteris sp., Yuccites sp., Neoglossopteris shansiensis, Gangamopteris? qinshuiensis, Phyllotheca yusheensis and Samaropsis milleri, the last four species generically affine to members of the Glossopteris Flora, thus showing the essential significance in biogeography. The sporopollen is represented by the Lundbladispora-Taeniaesporites-Cycadopites assemblage. In addition, there are also conchostracans, Apus and vertebrate fragments. The sporopollen, plants and conchostracans all point to the Early Triassic. This formation is tentatively correlated to early Early Triassic. 350-633m conformity Upper Permian Shiqianfeng Formation

2.2.2. North Tianshan-Junggar (Fig. 1, II14) The sequence of Junggar is as follows [8]. Lower Jurassic Badaowan Formation conformity 5. Late Triassic Haojiagou Formation. Grey mudstone, siltstone and fine sandstone, sometimes intercalated with conglomerate, carbonaceous shale and coal streaks. Both bed 4 and bed 5 yield basically similar plants, bivalves, gastropods, conchostracans, insects and Apus. The flora contains 37 known species in 25 genera, belonging to the Yanchang Flora. This indicates that the Huangshanjie and Haojiagou Formations are Late Triassic in age. 40-100m 4. Late Triassic Huangshanjie Formation. Greyish green lacustrine mudstone and siltstone intercalated with carbonaceous mudstone and limestone lenticles, yielding pisces Sinosemionotus. 15-450m 3. Middle to early Late Triassic Karamay Formation. Red mudstone, intercalated with a small amount of greyish green sandstone; upper part yields the pisecs Fukangichthys longidorsalis, Bogdania fragmenta and Fukangolepis barbaros, hence probably Upper Triassic; lower part yields vertebrates Parakannemeyeria, Sinosemionotus, Parotosaurus, Turfanosu-chus and Vjushkovia, alternated with and overlain by the Danaepsis-Bernoullia (Symopteris) Flora, and thus Middle Triassic. In addition, this formation also yields relatively abundant bivalves, conchostracans, ostracods, sporopllen, charophytes, Apus and

202

Palaeoniscus. 20-400m 2. Late Early Triassic Shaofanggou Formation. Purplish red sandstone intercalated with mudstone containing sporopollen of late Early Triassic age, also Labyrinthodontia and ?Lystrosaurus. 1. Early Early Triassic Jiucaiyuan Formation and top of Guodikeng Formation. They are composed of red mudstone and greyish green sandstone, yielding Dicynodontia-dominated vertebrates Prolacertoides, Santaisaurus, Chas-matosaurus, Lystrosaurus and Jimusaria, and the Darwinula minuta ostracod assemblage, thus belonging to the early stage of Early Triassic. Formations 1 and 2 have an overall thickness of 200-600m. conformity Upper Permian Goudikeng Formation 2.3. Other depositional areas (Text-fig. 1, Ill 2s, II 21) Besides the Shaanxi-Gansu-Ningxia basin, there are similar continental deposits in Yanshan and southern Northeast China, North Qilian-Hexi corridor-Beishan area and scarcely in South Tianshan. In the South Qilian area there developed marine deposits of platform type.

3. TRIASSIC OF THE EASTERN TETHYS OF EURASIA (Fig. 1, III) During the Triassic, the Tethys was an archipelagic ocean [5], composed of a mosaic of northward drifting blocks separated by rift seaways and micro-oceans. The demarcation line of northern or Eurasian and southern or Gondwanan Tethys probably lies along the YarlungZangbo line (Yin and Lin, 1994). The Eastern Eurasian Tethys consisting of areas within Chinese territory up to Karakorum is here called the Cathaysian Tethys, which is again subdivided into two parts along the Longmenshan--Red River (Song Hong) line. The eastern Cathysian Tethys, or South China, is now mainly covered by platform deposits such as in Yangtze, Cathaysia and part of Indochina Blocks, whereas most basinal sediments have not been preserved except in the Youjiang Basin. The western part, or the now Tibet-Qinghai Plateau, involves a series of paleo-latitudinally arranged blocks, represented by platform type and paraplatform type continental or marine Triassic and separated by what are now folded belts with major deep fractures and ophiolite zones. From south to north they are the Gangdise-Nyainqentanglha-(turning south) Baoshan block, the Bangong Co-Nujiang Folded Belt, the Karakorum-Qiangtang-Tanggula-Qamdo-(turning south)-Lanping-Simao block, the Bayan Har-Songpan-Garze Folded Belt and the Qinling Folded Belt.

3.1. Triassic of the Tibet-Qinghai Plateau The Qiangtang-Qamdo area and western Qinling Belt are chosen to represent this important Triassic area of China. 3.1.1. Qiangtang-Qamdo Area (Fig. 1, III~ a) The Lower-Middle and the Upper Triassic are better represented respectively in Qiangtang and Qamdo [9,10]. In the Kamru-Caka Formation of Qiangtang, the lower member contains two cycles composed of conglomerate, feldspathic arkose, siltstone and silty shale, totaling more than 630m thick. Faunal data permit recognition of three assemblages, from older to younger, the Claraia stachei assemblage, the C. aurita assemblage and the Eumorphotis

203

multiformis assemblage of Induan age. The middle member is a large suite of grey calcirudite, thin-bedded limestone and marl interbedded with siltstone and silty shale, nearly 1,000 m in thickness, containing the Eumorphotis inaequicostata-Pteria cf. murchisoni assemblage, and corresponding to early-middle Olenekian. The upper member contains silicarenite (100m) in the lower part and limestone (about 380m) in the upper, yielding the Spathian ammonoid Tirolites assemblage. In the Middle Triassic Kangnan Formation, the lower part contains grey sandstone, 90m thick, which grades upward into calcareous sandstone interbedded with sandy limestone, also 90m thick, while the upper part is composed of greyish black thin-bedded limestone, more than 100m thick, containing Anisian ammonoid, bivalve and brachiopod assemblages. In Qamdo [9,11], The lowermost horizon of the Triassic, the Dongdacun Formation, is a suite of grey rocks composed of sandstone, siltstone and mudstone in the upper and lower parts, and limestone in the middle part, totaling 840m in thickness. This contains fossil bivalves of the Middle to the Upper Triassic age. In some places, the lower part assumes a red color. The unit unconformably overlies the pre-Carboniferous schists, and underlies the Upper Triassic Jiapila Formation with a slight angular unconformity. The Upper Triassic may be divided in ascending order into the purplish red clastic rocks of the Jiapila Formation, the limestone of the Bolila Formation, and the coal measures of the Bagong Formation. The Jiapila Formation (2,161m thick) yields such fossils as Myophoria (Costatoria) mansuyi of Carnian age. The Bolila Formation (about 500m thick) is extremely rich in fossils of many groups, among which the ammonoids include 10 genera and 16 species, such as Cyrtopleurites bicrenatus, Anatibetites kelvini and Placites oxyphyllus of middle Norian age. Brachiopods are the most numerous, largely belonging to the Late Triassic, while the bivalves include Halobia cf. superbescens, H.cf partschi, also mainly of Norian age. In addition, there are also corals. The Bagong Formation may be divided into the Adula Member (below) and the Duogaila Member (above). The former is composed of black to greyish black shale intercalated with coal streaks, yielding Norian bivalves, such as Burmesia lirata, Costatoria napengensis and Indopecten, while the latter is composed of interbedded sandstone, siltstone and shale intercalated with coal seams, yielding D.-C. Flora and brackish bivalves, and is in conformable contact with the overlying Jurassic Chaya Group. 3.1.2. The Bayan Har-Songpan-Garze Folded Belt (Fig. 1, III14) This is represented by an extensive distribution of Triassic strata lying to the north and east of the HohXil-Jinshajiang Deep Fracture and to the west of Longmenshan. It has the same developmental history of the Proterozoic basement and Palaeozoic up to Middle Triassic platform as the Yangtze Platform, and the Late Triassic turbidite basin as the Qinling Belt. The Triassic development of the Bayan Har Folded Belt resembles that of the Qinling Belt and represents from the Induan-Anisian platform to the Ladinian-Late Triassic rift and sag deposits resulting from Indosinian palingenetic activities.

3.1.3. The western Qinling Folded Belt (Fig. 1, llllS). This belt is characterized by passive-margin deposits from the Lower Triassic to the Anisian that belonged to the northern margin of the Yangtze Platform. During the Ladinian, slope debris-flow calcirudite and flysch appearred, indicating rift and sag of the platform and development of a mobile belt. This lasted into Late Triassic until the terminal-Triassic orogeny. The stratigraphy may be stated as follows, taking the Guojiashan-Daheba (Dangchang County) section of Gansu as an example [12].

204 fault 7. Late Triassic Daheba Formation. Siltstone, calcareous siltstone, shale, micrite, fine greywacke and quartzitic arkosite, usually constituting rhythmic sequences, with carbonate contents decreasing upward; sediments containing turbiditic structures like graded beddings, flute and groove casts and yielding Late Triassic palinomorphs (30 species) and plants. > 2000m 6. Carnian(?) Dengdengqiao Formation. Greyish black thin- to medium-bedded limestone, containing Late Triassic radiolarians Betraccium microporum, Archaeospongoprunum collar and Flustrella spp., tentatively placed in the Carnian stage. 200m 5. Late(?) Ladinian Huashiguan Formation. Thin-bedded limestone, siltstone and slate, forming flysch intercalated with brecciform limestone, tentatively placed in the late Ladinian stage. 2400m 4. Early Ladinian Qinyu Formation: its upper part composed of siliceous limestone; lower part composed of thick-bedded of massive limestone, containing Ladinian conodonts Neogondolella mombergensis and N. excelsa, and a basal black shale, yielding the bivalve Daonella cf. moussoni, of early Ladinian age. 990m 3. Anisian Guojiashan Formation. Grey, thick-bedded to massive limestone, containing the bivalves Leptochondria subillyrica, L.subparadoxica, Bakevellia inaequivalvia and B. acutaurita, the gastropods Worthenia sp. and Naticopsis sp., the ammonoids Procladiscites? sp. etc., and the brachiopods Pseudospiriferina sp. and Parantiptychia sp., all being Anisian. 280m 2. Spathian Maresongduo Formation. Grey, thick-bedded, crystalline dolomitic limestone, dolomite, and purplish red micritic limestone, with evaporite-solution brexccia tens of meters thick at the top. Fossil zonation in ascending order: conodonts Neospathodus triangularis zone, N. hungaricus-N, hameri zone, and bivalves Chlamys weiyuanensis Bed, all being Olenekian. 882m 1. Griesbachian-Smithian Zalishan Formation. Grey thin- to medium-bedded micrites intercalated with silty shale, including respectively, in ascending order, 4 conodont zones: Hindeodus parvus, Neospathodus dieneri, N pakistanensis and PachycladinaParachirognathus, and 3 bivalve beds: Claraia concentrica, C. aurita and EumorphotisEntolium. 628m conformity Upper Permian Changxing Formation: oolitic limestone.

3.2. Triassic of South China This region includes 3 subregions, i.e., the Yangtze Platform, the Cathaysia Platform and the Youjiang Folded Belt. Table 1 shows the comparison among the three subregions: 3.2.1. Yangtze Platform (Fig. 1, II12l) This subregion is represented by sections in southwestern Guizhou, which are briefly introduced as follows [13]:

205 Table 1. A comparison of characteristics among different subregions of South China [3]

Stratigraphical development

Sedimentary characteristics Biotic province and biofacies

Yangtze Platform Completely developed with Lower, Middle and Upper Series (locally lacking Ladinian and Carnian strata) Normal marine to evaporite facies of stable type Tethyan, mainly with benthic taxa

Volcanic activities very rare

Youjiang Folded Belt Mainly composed of Lower and Middle Series, Upper Series only locally found

Cathaysia Platform Lower Series locally, Middle Series lacking, Upper Series most developed

littoral-neritic clastic facies of platform type mainly with bivalve Tethyan, mainly of planktonic ammonoid faunas of CircumPacific type and halobiid facies with continental with sporadic medium-acidic medium-acidic eruptions occasionally volcanic rocks found in late stage developed in early, middle and late stages flysch facies of mobile type

Lower-Middle Jurassic: Ziliujing Group conformity Norian-Rhaetian? Erqiao Formation 18. Sandstone Member. Lithic quartzarenite intercalated with siltstone, mudstone and carbonaceous shale, containing the plants Clathropteris meniscioides and Dictyophyllum cf. nilssoni. 110-400m 17. Shale Member. Clayrock, siltstone, carbonaceous shale and thin coal seams, containing the plant Lepidopteris ottonis, and the bivalves Indosinion elliptica, I. emeiensis in northern Guizhou. 10-70m Norian Huobachong Formation 16. Paralic rocks composed of grey to greyish green lithic quartzarenite and siltstone with carbonaceous shale and coal beds, yielding bivalves gunnanophorus boulei (usually upper) and Burmesia lirata (usually lower); and plants Taeniocladopsis rhizonoides and Pterophyllum cf. ptilurn; together with brachiopods and ostracods. 261-678m Carnian Formations 15. Banan Formation. Rhythmic interbeddings with unequal thicknesses composed of yellowish grey fine- to medium-grained lithic quartzarenite, siltstone and clayrock, yielding bivalves Costatoria kweichowensis and Angustella angusta and an ammonoid genus Trachyceras; together with brachiopods and plants. In corresponding formations of eastern Yunnan and Longmenshan area there have been found Halobia comata, H. superba, H. yunnanensis and Tosapecten. Guizhou is not typical for the Late Triassic plant zonation in South China. Different from the Yanchang Flora of North China, that of South China is called the Dictyophyllum nathorsti-Clathropteris meniscioides or D.-C. flora, which can be subdivided into a lower (Carnian--Middle Norian) Rireticopteris--Pterophyllum longifolium assemblage and an 150-463m upper (Late Norian--Rhaetian) Ptilozamites--Lepidopteris assemblage.

206 14. Laishike Formation. Rhythmic interbedding with unequal thicknesses, composed of grey or greyish green clayrock with siltstone and sandstone, yielding ammonoids Trachyceras cf. janurius and Paratibetites clarkei, and the bivalve Halobia rugosoides. 67-732m Ladinian-Carnian Falang Formation 13. Carnian Wayao Member. Grey to black calcareous clay rock intercalated with limestone and marl, yielding ammonoids Protrachyceras deprati, P. douvillei; the conodont Gondolella navicula; bivalves Halobia kui, H. rugosoides, Daonella bulogensis bifurcata; and crinoids. 16-238m 12. Ladinian Zhuganpo Member. Grey medium-bedded micrite and nodular limestone, yielding bivalves Halobia subcomata, Daonella bulogensis; the ammonoid Protrachyceras primum; and the aquatic reptilian Kueichousaurus hsui 30-696m Ladinian Yangliujing Formation 11. Light grey to grey dolomite, breccia dolomite and a small amount of limestone (upper part) with rare fossils. 20-230m Anisian Guanling Formation 10. Shizishan Member. Grey to dark grey wormlike calcirudite and argillaceous limestone, yielding bivalves Leptochondria illyrica, Costatoria goldfussi mansuyi; and the ammonoid Prognoceratites sp. 0-530m 9. Songzikan Member. Lower part composed of dolomite and dolomitic limestone, with brecciated structure due to evaporite solution; middle-upper part of variegated clayrock intercalated with marl, yielding bivalves; basal part taking a 1-3m yellowish green vitric tuff as its boundary with the Lower Triassic. 108- 390m In the platform-marginal area the Guanling Formation changes into the Qingyan Formation, which yields ammonoids, in ascending order, Parapopanoceras nanum

(Leiophyllites angustum billicus, Hollandites yangbunaensis), Nicomedites yohi, Paraceratites binodosus, P. trinodosus. Olenekian Yongningzhen Formation 8. Member 4. Yellow to grey dolomite and karst breccia intercalated with clayrock, containing rare fossils. 26-218m 7. Member 3. Grey micrite, usually with wormlike rudaceous structure, intercalated with dolomite, yielding bivalves Entolium discites microtis, Eumorphotis inaequicostata. 7m 6. Member 2. Interbeddings with unequal thicknesses, composed of purplish red to yellowish green clayrock, marl and dolomite, yielding the ammonoid Tirolites spinosus, and the bivalve Pteria cf. murchisoni. 24-221m 5. Member 1. Micrite, calcarenite, bioclasts and oolitic limestone, yielding bivalves Eumorphotis teilhardi and E. hinnitidea. 24-290m Induan Yelang Formation or Feixianguan Formation (clastic facies), Daye Formation (carbonate facies) 4. Member 4. Purplish red to yellowish green clayrock, yielding the blivalve Eumorphotis multiformis. 76m 3. Member 3. Grey limestone intercalated with sandy mudstone, with upper part yielding the bivalve Eumorphotis multiformis and the lower part yielding bivalves E. multiformis, Claraia aurita and C. stachei. 284m 2. Member 2. Yellowish grey to bluish grey siltstone and mudstone, yielding bivalves Claraia griesbachi, C. clarae and C. aurita; and the ammonoid Ophiceras demissum. 217m

207 1. Member 1. Yellowish green to grey sandy silty mudstone, containing the bivalve Pseudoclaraia wangi; the ammonoid Ophiceras sinensis; and at its base bivalves Towapteria scythica, Pteria ussurica variabilis, together with the conodont Hindeodus 19m parvus conformity Upper Permian Changhsing Formation (limestone) or Dalong Formation (silicolite and clayrock). The relief of the Yangtze subregion in Early Triassic was higher to the west and lower to the east. During Early Triassic the facies changed eastwards from elastics to carbonates. In Anisian time, this subregion became higher to the east and lower to the west. Reversely, The facies changed eastwards from carbonates to elastics. In the Ladinian Stage, the whole subregion became elevated, with subsequent marine deposits confined to a few areas including southwestern Guizhou, eastern Yunnan, western Sichuan, and western Hubei. Although the names of formations are different in different areas, the whole subregion is identical in biotic features.

3.2.2.

Cathaysia Platform (Fig. 1, |II2 2)

This subregion is similar to the Yangtze both in lithological character and in fossils of the Lower and Middle Triassic. Anisian deposists only locally developed, and the Ladinian was lacking due to uplift. The Middle-Late Triassic Indosinian orogeny changed the tectonic framework of South China. The elevation of the Yunkai-Xuefeng-Huangling area isolated this subregion from the Yangtze Subregion. As a result, this subregion was separated from the Tethys, and belonged to the Palaeo-Pacific regime i14j. During Late Triassic, terrestrial sediments with coal measures similar to those of the Yangtze were deposited. The sea intruded from both south and east, forming the Guangdong-Fujian-Hunan-Jiangxi and Southern Jiangsu gulfs respectively, where the biota belonged to the Circum-Pacific type.

3.2.3.

Youjiang Folded Belt (Fig. 1, 11123)

The Youjiang Folding Belt may be represented by the sections around the western and southwestern Guangxi which are briefly related below [ 15]: Lower Jurassic Wangmen Formation conformity 6. Norian (and Rhaetian?) Fulong'ao Formation. Upper member composed of purplish red conglomerate and sandstone intercalated with mudstone and coal seams, yielding fossil plants Clathropteris meniscioides, Dictyophyllum nathorsti, Lepidopteris cf. ottonis, and brackish bivalves; the lower member contains purplish red sandstone and siltstone intercalated with mudstone and conglomerate 425-4552m 5. Carnian?-Norian Pingdong Formation. Purplish red gravel-bearing sandstone, sandstone, siltstone and mudstone, yielding the marine bivalves Waagenoperna obrupta, Modiolus problematica, etc. At present, there are still controversies over the character of this bivalve assemblage, in which some people have identified elements of the Yangtze (Tethyan) type, such as Yunnanophorus, while others have listed some elements of the Pacific type, such as Bakevelloides liuyangensis, Parainoceramus matsumotoi, etc. 210-3114m unconformity 4. Ladinian Hekou Formation. Turbiditic sandstone interbedded with mudstone or mudstone intercalated with siltstone and limestone; divisible into upper and lower members by a

208 coarse sandstone bed, yielding the ammonoid Protrachy- ceras douvillei and the bivalves Daonella lommeli and D. indica. 794-3129m 3. Anisian Baifeng Formation. Turbidites composed of sandstone, mudstone; flysch with tuff or tuffstone in its basal part; yielding ammonoids Balatonites balatonicus, Danubites kansa, Hollandites sp. and Japonites sp.; and bivalves Daonella producta, D. elongata. 1252-6484m Lower Triassic Luolou Group. 2. Neritic mudstone and shale intercalated with siltstone, fine sandstone, marl and limstone, sometimes silicolite, silicious shale, conglomerate, volcanic clastics and volcanics which may locally form the main portion of the group. This group yields abundant ammonoids and bivalves; the former constitutes 9 zones in ascending order: Induan, Ophiceras sinense, Vishnuites marginalis, Proptychites kwangsiensis, Koninckites lingyunensis; Olenekian, Owenites costatus, Pseudowenites oxynostus, Tirolites darwini, Columbites costatus, 37-2042m Procarnites oxynostus. conformity 1. Upper Permian, Dalong Formation: silicolite The Youjiang subregion differs from the Yangtze and Cathaysia subregions in the presence of frequent and widespread volcanic activities which continued from the Permian, and there occurred a rapid sag in the Middle Triassic that accepted a great thickness of turbidites. By the end of Middle Triassic, the whole subregion was folded and uplifted. During the Late Triassic, only foreland basin deposits of continental and paralic purplish red clastic rocks accumulated on its southern piedmont and further on what was previously the Qinzhou "Geosyncline', the northeast branch of the Indosinian "Geosyncline'.

4. TRIASSIC OF THE EASTERN PART OF GONDWANAN TETHYS (Fig.l, IV) Within the border of China, this area mainly lies in the Himalayas, including the Himalayan (northern margin of Indian Plate) platform margin and the Yarlung Zangpo-Indus Folded Belt.

4.1. Triassic of the Himalayas platform margin (Fig. 1, IV1) This may be represented by the Tulong Section of Nyalam County, Xizang [9]. Stratigraphical names in parentheses are from [ 10]. Lower Jurassic (?) Pupuge Formation. Sandstone, shale and sandy limestone conformity 10. Rhaetian Zamre Formation (upper Derirong Formation). White massive coarse silicarenite with conglomerate at base. The intercalated carbona-ceous shale yields the sporopollen Classopollis sp., and Punctatosporites sp. 165.2m Norian Stage 9. Derirong Formation (lower, middle Derirong Formation and top of Qulong-gongba Formation). Interbeds of light grey thin-bedded quartzose siltstone and brown thin-bedded fine quartzarenite intercalated with carbonaceous shale, yielding bivalves Indopecten cf. himalayensis, L cf. margariticostatus, Myophoricardium fulongense, and Palaeocardita mansuyi, sporopollen, and acritarchs. 240.3m 8. Qulonggongba Formation. Grey shale intercalated with quartzarenite and bioclastic limestone, containing extremely rich fossils including ammonoids in ascending order,

209

Indojuvavites angulatus, Cyrtopleurites socius ~ibetites rayili, Paratibetites wheeleri), "Himavatites columbianus' (Dittmarites, Distichites); and bivalves Burmesia lirata, Indopecten serraticostatus, Pergamidia timorensis, Halobia superbescens and many other species; together with brachiopods, ostracodes, conodonts, foraminifers, sporopollen, nautiloids, belemnities, ichthyosaurids. 571.3m 7. Yazhi (Dashalong) Formation. Rhythmites composed of greyish black shale and bioclastic limestone, yielding ammonoids, in ascending order, Nodotibetites nodosus, Griesbachites himalayanus + Gonionotites tingriensis and bivalves Halobia cf. sirii, Myophorcardium tulongense, and Unionites griesbachi; together with brachiopods, conodonts, ostracods, foraminifers, sporopollen, acritarchs and nautiloids. 66.6m Carnian Stage 6. Kangshare (Zamure) Formation. Lower part composed of sandy shale; upper part of bioclastic limestone with nodular strucutre, containing ammonoids, in ascending order: Indonesites dieneri, Haplotropites lyelli+H, acutus, Parahauerites acutus, and conodonts Epigondolella diebeli, and Neogondolella polygnathiformis; together with bivalves, brachiopods, ostracods, bryozoans, and foraminifers dominated by miliolids. 4m Ladinian Stage 5. Upper member of Qudenggongba (Laibuxi) Formation. Upper and lower parts dominated by limestone while middle part composed of dark green sandstone and shale, containing ammonoids, Joanites kossmati, Protrachyceras longobardicum, etc. (totaling 14 genera and 18 species); and bivalves Daonella lommeli, D. indica and Posidonia sp.; together with brachiopods, conodonts, ostracodes, many species of foraminifers, sporopollen, crinoid stems and radiolarians. 127m Anisian Stage 4. Lower member of Qudenggongba (Laibuxi) Formation. Variegated silty shale, containing abundant brachiopods, such as Tulongospirifer stracheyi, Diholkorhynchia sinensis, Nudirostralina griesbachi, and N. mutabilis, with less abundant ammonoids, such as Hollandites voiti, Japonites magnus, etc. in addition to forminifers, ostracodes, bivalves, conodonts and nautiloids. 65.1m Olenekian Stage 3. Upper Member of Tulong (Kangshare) Formation. Light grey thin- to medium-bedded limestone, intercalated with variegated shale in middle part, yielding ammonoids Procarnites xizangensis, Owenites cf. egrediens, conodonts Neospathodus homeri, N. timorensis, N. waageni, N. pakistanensis; together with bivalves, nautiloids and brachiopods. 27.0m Induan Stage 2. Lower Member of Tulong (Kangshare) Formation. Composed of purplish red to variegated shale in the upper part and bioclastic limestone, thin-bedded limestone and dolomitic limestone in the lower part, yielding ammonoids Gyronites psilogyrus, Prionolobus lilangenis, Ophiceras cf. demissum, the conodonts Neospathodus dieneri, N. kummeli, Neogondolella carinata; and the bivalve Claraia sp.; near the base have been found Hindeodus parvus and Otoceras woodwardi and even lower there are O. latilobatum and brachiopod Waagenites (already Permian) [ 16]. 83.2m disconformity 1.Upper Permian Nimaloshiza Formation. Greyish black shale, containing Upper Permian sporopollen, acritarchs, scolecodonts, arthropods, together with small brachiopods and bivalves. 18m

Chronostratigraphy Se-

Stage

North China

rles

Norian

N TianshanJunggar Haujiagou

Rhaetian

U

Cathaysian Tethys South China Tibet-Qinghai

Central Asia

Yangchang Gr.

Huangshanjie

Yangtze

Youjiang

QiangtangQamdo

Erqiao

Fulong' ao

Bagong

Banan Laishike Wayao

Pingdong

Anisian

Ermaying

Karamay

Jiapila

Hekou

Dongdaqiao

Yangliujing

Diener. Induan

Griesb.

Liujiagou

Guanling

Baifeng

Qinyu

Kangnan

Guojiashan

U Shaofanggou Yongningzhen Jiucaiyuan Guodikeng (top)

Yelang (Daye Feixiangkuan)

F i g u r e 2 C o r r e l a t i o n of Triassic s t r a t a of C h i n a Gr, G r o u p ; t h e w o r d " F o r m a t i o n ' is omitted.

Huashiguan

I I

M

Olene- Spath. kian Smith. Heshanggou

Derirong Qulonggongba

Dengdeng-qiao Kangshare

Zhuganpo Tongchuan

Himalaya

Yazhi

Carnian

Ladinian

Age

Zamre Daheba

Bolila

Huobachong

Qinling

Gondwanan Tethys

Qudenggongba L

Mar~songduo o

M

Luolou Gr.

KalIlru

Caka

A

Tulong

-

Zalishan

211

4.2. Triassic of the Yarlung Tsangpo and Indus Rivers (Fig. 1, IVy) These tectonically active depositional regimes may be divided into two belts. The North Belt is distributed along the ophiolitic melange zone of the Yarlung Zangpo. The melange includes flysch, ophiolites, volcanics, strongly tectonically transformed and thus no Triassic sequence has been recognized. The South Belt lies between the North Belt and the platform margin of the Himalayas. The Triassic there includes deep-water flysch, intercalated with a large amount of volcanic rocks and silicolites, slightly metamorphosed and with little or without melange.

5. DIVISION AND CORRELATION OF THE TRIASSIC IN CHINA The correlation of the Triassic in China is shown in Figure 2. A synthetic correlation of biostratigraphy of the Triassic in China and its correlation with adjacent regions is given in Figures 3--6. Ammonoid, bivalve and conodont biostratigraphy and their correlations with other parts of the world have been published in Yin (1997). Owing to the limited space, only a synthetic scheme of the five major Triassic fossil groups in China (ammonods, conodonts, bivalves, nonmarine vertebrates and floras) is given together with sequence stratigraphy and sea level changes. The synthetic zonation is based upon the following data indicated already in the text: the Early Triassic ammonoids--Youjiang region [17], Middle Triassic--Early Carnian ammonoids--Yangtze region (Guizhou) [13], Late Carnian and Norian ammonoids--Himalayas [18], bivalves--Yangtze region (Guizhou) [19], conodonts-Himalayas and Hubei [20-22], plants--North China [23,24], vertebrates--North China and North Tianshan-Junggar Basins [25]. Both sequence stratigraphy and sea level changes are based on data from South China, where marine sequence was most completely developed. The correlations with adjacent regions and different parts of the world, are shown on Figure 3. A detailed correlation with the Tethys, Boreal and adjacent regions has been shown in [2]. In this paper only a brief correlation with the Tethys as a whole is made plus recent data from the Primorye (Russian Far East) [26,27] and Indochina (basically Vietnam, Laos and Cambdia [28]. The Tethys scheme is basically taken from [29], with minor changes based on recent discussions on the Permian/Triassic boundary, Anisian/Ladinian boundary and Rhaetian [30]. It is hard to correlate the European three- or four-fold Middle and Upper Triassic substages with Chinese ones, so in this paper only Upper and Lower Substages are used. For example, the Lower Anisian may correspond to the Aegian and the Bithynian, and the Upper Norian may correspond to the Alaunian plus part of the Sevatian. The marine Chinese zonation (Fig. 4, Fig. 5 partly) shows remarkable similarity with that of Indochina (Vietnam) throughout the Triassic. The difference of some corresponding zonal fossils, e.g. the Rhaetian Unionites (Indochina) and Indosinion (China), may be merely nominal but essentially congeneric. Some corresponding zonal fossils may be different but morphologically similar, e.g. Costatoria curvirostris (Vietnam) and C. goldfussi mansuyi (China), or the Vietnam fossil may occur in the same zone of China, but not mentioned in Figure 3, e.g. Claraia concentrica and Daonella elongata (Vietnam). The similarity is because during the Triassic northern Vietnam and northern Laos were small

212

EPOCH STAGE

BIOSTRATIGRAPHY OF ADJACENT REGIONS TETHYS PRIMORYE INDOCHINA

208 ~D

Choristoceras marshi Rhabdoceras suessi

Monotis ochotica

Halorites macar Himavavites hagarti Cyrtopleurites bicrenatus

Eomonotis scutiformis Otapiria ussuriensis

Gervillia inflata

212

r

Juvavites magnus Malayites paulckei Guembalites jandianus

cD

220

Anatropites Tropites subbullatus Tropites dilleri

Pterosirenites kiparisovae

/

StriatosirenitesArietoceltites

Margaritropites

A ustrotrachyceras austriacum Trachyceras aonoides

228

Fankites regoledanus Protrachyceras archelaus P. gredleri Eoprotrachyceras curionii

234

241

~ = ~)

"~ i

.d~

Flemingites rahilla Gyronites frequens Ophiceras tibeticum Otoceras woodwardi

"=

(partly)

~9

246 J

Nevadites secedensis ~D Reitzites reitzi P. trinodosus Balatonites balatonicus A nagymnitoceras ismidicum Nicomedites osmani , Aegeiceras ugra Tozericeras spiniger =~ Tirolites cassianus ~ Wasatchites pakistanum "~ meekoceras gracilitatis

Discotropites

Ussurites ProtrachycerasRimkinites Daonella densisulcata Ptychites oppeli Acrochordiceras kiparisovae

Kellnerites Paraceratites Balatonites

Leiophyllites pradyumna

Neocolumbites insignis Tirolites-Amphistephanites Anasibirites nevolini Hedenstroemia bosphorense

Tir ol ites-Columb ites

Gyronites subdharmus

FlemingitesParanorites Gyronites-Koninckites

Glyptophiceras ussuriensis

Ophiceras commune

251 Figure 3

Synthetic correlation of the Triassic of China and adjacent regions.

Part 1" chronostratigraphy and biostratigraphy of adjacent regions.

213

CHRONOSTRATIGRAPH ! Y STAGE 208

BIOCHRONOSTRATIGRAPHY OF CHINA AMMONOID

CONODONT Misikella posthersteini Misikella hersteini

212 E. bidentata U

"Himavatites columbianus' Cyrtopleurites socius

E. postera

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Figure 4 Synthetic correlation of the Triassic of China and adjacent regions. Part 2: ammonoid and conodont zonations of China.

214

BIVALVE

BIOSTRATIGRAPHY OF CHINA PLANT

VERTEBRATE

Indosinion

Yunnanophorus boulei

Burmesia lirata

Danaeopsis fecundaBernoullia (Symopteris) zeilleri (Dictyophyllum nathorsti-Clathropteris meniscioides in South China)

Halobia superba Costatoria kweichoowenis Fukangichthys (Bogdania Fukangolepis) Halobia rugosoides Halobia kui Daonella lommeli Daonella indica AnnalepisTongchuanophyllum Sinokannemeyeria Parakannemeyeria

Daonella producta

Costatoria goldfussi mansuyi Leptochondria illyrica

Shansisuchus Shansiodon

Voltzia-Aipteris wuziwanensis

Paoteodon Shanbeikannemeyeria

Sp Pteria cf. murchisoni

Fugusuchus Benthosuchidae

Sm Pleuromeia- Voltzia Eumorphotis multiformis Claraia aurita Claraia stachei Pseudoclaraia wangi Towapteria soythica

Chasmalosaurus Lyslrosaurus

Figure 5 Synthetic correlation of the Triassic of China and adjacent regions. bivalve, plant and vertebrate zonations of China.

Part 3:

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216 blocks in the vicinity of the Yangtze and their southern parts belonged to Indochina Microplate, located to the south of the Yangtze and drifted together with it. The marine Chinese zonation is also compatible with that of the Tethys since it belonged to the Tethys. The similarity is more conspicuous in the Lower and Middle Triassic. The Upper Triassic zonation of China shows apparently eastern Tethyan aspect in ammonoids (Indonesites, Nodotibetites, Indojuvavites) and bivalves (Burmesia, Yunnanophorus), reflecting the influence of Indosinian Orogeny. Primorye, as well as Japan, belonged to the northwestern Pacific (2). During Early Triassic their connection with the Tethys was open and the water temperature was close to each other, thus the zonations were similar at least at generic level. Beginning from Middle Triassic onwards due to the Indosinian Orogeny there was a great regression in the Mongolo-Okhotsk, Yangtze, Cathaysia and Indochina. Consequently the seaway connection with the Tethys was shut and the biota became increasingly CircumPacific type. Their Late Triassic zonation was essentially boreal, identical with that of Verkhoyan. The terestrial Chinese zonation (Fig. 5) is mainly based on Central Asia except the Himalayas. For the Triassic Eurasian flora Dobrushkina [33] established a northern Ural (Siberia) type and a southern Europe-China type. The Upper Triassic of the latter consists of an Iran-Vietnam subtype and a Greenland-Japan subtype which correspond to South China (D.-C. Flora) and North China (D.-B. Flora) respectively. The Ladinian-Carnian Scytophyllum Flora also exists in China, with the endemic element Tongchuanophyllum. The PleuromeiaVoltzia Flora was correlatable throughout Eurasia (from China to Europe) and Gondwana (South America and Australia). The Early Triassic vertebrates of China can be correlated to the Vokhmian horizon of the Vetluga Formation, Dvina River of Russia [34] and Middle Beaufort Fauna of South Africa [35]. Its Middle Triassic fauna corresponds to Yarenskiy Formation of Russia and Upper Beaufort plus Lower Molteno of South Africa and Manda Beds of Tanzania. These occurrences are distributed respectively north and south of the Tethys, thus forming bipolar distribution. This paper has not used the Lower Triassic part of the global scheme of [36], because his correlation of the Houshanggou Formation with the Jiucaiyuan Formation contradicts Chinese stratigraphy and his timing of the Ermaying Fauna at Olenekian-Anisian contradicts Chinese stratigraphy based on coexisting plants. These need further investigation.

6. TRIASSIC EVENTS IN CHINA AND ADJACENT REGIONS 6.1. Sequence stratigraphy and sea level changes: The whole Triassic System constitutes a complete 2 nd order supercycle set, Upper Absaroka A, with four 2 nd order supercycles and twelve 3rd order sequences. Figure 6 is mainly based on the Yangtze.Platform. The age of sequence boundary is only by estimation. In accordance with the idea that biostratigraphic boundary lags behind a sequence boundary for a period of low stand track [37], it has been discovered that the turning point from the great Late Permian regression to transgression happened in latest Permian rather than at the Permian-Triassic boundary [38,39]. Similarly, the upper boundary of the Upper Absaroka A should be in late Rhaetian rather than at the Rhaetian-Hettangian boundary. In contrast to western Pangea where owing to the opening of the Atlantic the general tendency of Triassic is transgressive, in eastern Pangea including China it is generally regressive. This 2nd supercycle set, same as in the whole

217 northern hemisphere, is bipartite. The Lower Triassic to Anisian forms the part one (UAA1-2), usually marine, and the Upper Triassic forms the part two (UAA 3-4), usually shallow neritic, paralic to terrestrial, and with Ladinian either as relict of the part one or prelude of the part two. In China, except for the Himalayas, there is usually a hiatus or a sea-shallowing between the two and a conspicuous paleoclimatic change from the arid part one to the humid part two. The latter often unconformably or disconformably overlies different older strata, reflecting the influence of the early Indosinian Orogeny during the transitional period from Middle to Late Triassic. In Supercycle UAA-1, usually four sequences can be recognized, roughly corresponding to the four Lower Triassic substages but again with a certain lag [40,41]. Sometimes Sequences 1 and 2 may incorporate into one sequence. The transgressive zenith of the four sequences varied in different localities because, as in the case of the Yangtze, it was influenced by the timing of subduction and collision of different blocks in eastern Tethys. In UAA-2, the Anisian is commonly a transgression followed by the widespread Ladinian regression[42]. In the part two, Late Carnian and Early Norian were the peak of transgression. The Burmesia transgression extended into the South Qilian area of Central Asia (Fig. 1, II21) [43]. The Rhaetian in China is totally terrestrial and its identification is based solely on plants and thus is doubtful. Many faunal researchers tend to deny the existence of the Rhaetian in China and take its highest Triassic as Late Norian. In the Cathaysian Tethys almost everywhere there is a hiatus between Triassic and Jurassic. Lowermost Jurassic Psiloceras planorbis and P. provincialis have only been discovered in southern Guangdong and the Himamlayas (Longzi County) respectively. 6.2. Tectonic and other events

Global changes at the Permian-Triassic transition are also displayed in China and the whole East Asia. They include the late Permian regression, accompanied by oceanographic anomalies, anoxic event and mass extinction. East Asia is characterized by widespread Early Triassic basalts in Siberia, esp. the Tunguss Trap and volcanism at the Permian-Triassic transition in South China [39]. The Early Indosinian Movement In Middle Triassic is mainly epeirogenic. The epeirogeny includes the Ladinian regression occurring on many intermediate blocks of the Eurasian Tethys, the uplift of Central and North Asia Palaeocontinent as a whole, and the uprising of Circumpacific margins. Rift-and-sag processes of Palaeotethys margins took place. The Middle Triassic orogenies occurred in Yanshan, North Qinling, eastern Kunlun, the ThreeRivers (Sanjiang) region, Youjiang and a large part of Japan. The Late Indosinian Orogeny in Late Triassic is displayed in the folding and upheaval of Palaeotethyan active belts and strong folding and volcanism along the Circum-Pacific. The outer belt of the Circum-Pacific in Sikhote-Alin and Japan, as well as the Sino-Russian border of Jilin and southern Heilongjiang Provinces, underwent strong volcanism. There are also depositional discontinuities in marginal Palaeo-Asia and intermediate blocks, such as southern Jiangsu Province, central Guizhou Province and the Longmenshan area of the Yangtze. The terminal Triassic regression in East Asia is a part of the worldwide regression, which occurred synchronously with the terminal Triassic mass extinction. With folding and upheaval of active belts in the Cathaysian Tethys the Palaeo-Asia was integrated into a whole continent, except for the Gondwanan Tethys. Meanwhile the Circum-Pacific belt displayed for the first time in geohistory its significance and integrity. Thus, unlike America, Africa and Europe where Late Triassic witnessed the beginning of the Pangaea breakup (riftogenesis and volcanism), in eastern Pangea the main process was integration instead of disintegration.

218

Acknowledgements: Mr. Peng Yuanqiao helped in drawing the tables and figures. I thank Prof. Yang Zunyi and Dr. Y.D. Zakharov for reviewing this paper.

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Persian-Triassic Evolution of Tethysand WesternCircum-Pacific H. Yin, J.M. Dickins,G.R. Shi and J. Tong (Editors) o 2000 ElsevierScienceB.V. All rightsreserved.

221

The Triassic of Indochina Peninsula and its interregional correlation Vu KHUC Geological Museum, 6 Pham Ngu Lao, Ha Noi, Viet Nam In some basins of the Indochina Peninsula, the Triassic sequences are composed of all seven stages of the Triassic system. In some others, the sequences are more or less curtailed, and include only sediments of a few stages. In the studied region, one can distinguish two main types of Triassic sequences: 1) the type of An Chau Basin, where the Anisian consists of a felsic volcanogenic formation which lies unconformably upon older formations, and the Carnian is represented by continental red beds or completely absent in the sequences; 2) the type of Song Da Basin, where the Anisian consists of a calcareous formation which lies conformably upon the Lower Triassic, and the Carnian is represented by marine sediments bearing deep-dwelling halobiids. The first type includes the Triassic of the An Chau Basin (NE Viet Nam), Sam Nua Basin (Central Viet Nam and Central Laos), Ta Thiet Basin (S Viet Nam) and N Cambodia (?) area. The second type comprises the Triassic of the Song Da Basin (NW Viet Nam), Nam Beng Basin (?) (N Laos), Hon Nghe Basin (S Viet Nam), Lampang-Phrae Basin (N Thailand) and Shan States area (?) (N Myanmar). Triassic sediments of the Indochina Peninsula contains abundant fossils, which make the interregional correlation of them easy. 1. INTRODUCTION The territory of Indochina considered in this work consists of the mainland of present SE Asia, including (from east to west) Viet Nam, Laos, Cambodia, Thailand, Malayan Peninsula and Myanmar. The first works on the Triassic of this large area have appeared earlier than 110 years ago, such as those on the late Triassic flora from the Hon Gai coal basin (NE Viet Nam) by Zeiller [1, 2, 3]. Later, in 1896 Diener [4] reported on the finding of two middle Triassic ammonites from "Tonkin" (N Viet Nam); in 1900 Newton [5] published the results of his study on some late Triassic bivalves from the locality belonging now to Singapore; and in 1908 Healey [6] gave the description of an abundant collection of Rhaetian molluscs from Napeng (Myanmar). However, the study of Triassic stratigraphy developed only in the last half of this century, related to the geological survey on small and middle scales in different countries of Indochina. In general, Triassic sequences in Indochina are composed of all 7 stages of the Triassic system. They are characterized mainly by marine sediments. In some regions continental facies appeared since only Carnian, in most cases, Norian or Rhaetian.

222

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The most complete sequences of Triassic can be observed in NE Viet Nam, NW Viet Nam, and Shan States of Myanmar, where the beds have been dated from Induan to Rhaetian, bearing different fauna and floral assemblages.These form reliable bases for the dating and correlation of the sediments. The Triassic section of other regions are more or less curtailed. Following below Triassic sequences of different basins of Indochina, including basins in NE Viet Nam, NW Viet Nam, N Central Viet Nam, S Viet Nam, Upper Laos, N Cambodia, N Thailand, Central Belt of Malaysia, Shan States and Tenasserim Basin of Myanmar (Fig.l) will be described.

223 2. D E S C R I P T I O N OF T R I A S S I C S E Q U E N C E S IN T H E I N D O C H I N A PENINSULA 2.1. Northeast Viet Nam

In NE Viet Nam Triassic sediments have a largest distribution with a most complete section in the Mesozoic An Chau Basin (1, Fig.l). In this area, during Triassic the depositional accumulation happened in 3 cycles: 1) Lower Triassic; 2) Anisian-Carnian; and 3) Norian-Rhaetian. The most characteristic features of Triassic of this basin are as follows: 1) Anisian is composed of thick members of felsic volcanics, lying unconformably upon older formations; 2) the continental facies appears in the Carnian and later; and 3) Norian-Rhaetian are characterized by coal-bearing formation. Lower Triassic of the An Chau Basin has been divided into two formations. Lang Son Formation [7] is composed of flyschoid beds with sandstone, siltstone and clay shale with some interbeds of felsic volcanics; 500-600 m thick. These beds yield such Induan ammonoids as Glyptophiceras langsonense, Lytophiceras sp., KonincMtes vidarbha, together with various Claraia, the earliest of them is C. wangi, and then C. griesbachi, C. stachei, C. vietnamica. The upper part of the formation yields Eumorphotis venetiana, Pteria ussurica, etc.. This fauna dates the formation as Induan. Bac Thuy Formation [8] includes marl, clayish limestone, calcareous sandstone, siltstone and clay shale; 150-250 m thick. Marl beds of the lower part of the formation contain early Olenekian ammonoids, such as Flemingites aff. F. flemingianus, Meekoceras cf. yuMangense, Owenites carinatus, Paranorites praestans, etc., whilst clay shale of the upper part contains late Olenekian ammonoids Columbites cf. parisianus, Tirolites sp. together with bivalves. All this fauna dates the formation as Olenekian. Middle Triassic of this basin, lying unconformably upon Upper Paleozoic limestone, has been divided into two formations. Khon Lang Formation [9] is composed of tuffaceous sandstone, rhyolite, dacite and tufts; 800-1000 m thick. Basal beds of the formation yield such ammonoids as Gymnites cf. incultus, Ceratites aff. C. nodosus, that dates the formation as Anisian. Na Khuat Formation [7] consists of limestone, marl, siltstone, clay shale and sandstone; 1200 m thick. Limestone and marl of the lower part contain Kellnerites samneuaensis, Costatoria proharpa, C. chegarperahensis, etc. of late Anisian age. From the upper part bivalve assemblages include Trigonodus sandbergeri, T. trapezoidalis, Costatoria goldfussi, C. inaequicostata, etc. of Ladinian age. Based on these fossils the Formation has been regarded as Middle Triassic (from late Anisian). Upper Triassic of the An Chau Basin is composed of a Carnian formation, which overlies conformably the above-described Middle Triassic sediments, and an Upper Triassic coalbearing formation, which lies unconformably upon other older sediments. Mau Son Formation [7] consists of red continental siltstone, sandstone, claystone, greenish marl and quartzite-like sandstone; 1200-1500 m thick. The marl furnishes freshwater bivalves, such as Utschamiella cf. opinata, U. cf. elliptica, Tutuella cf. nuculiformis, and locally sandstone yields rare estheriids. This formation have been assigned to the Carnian.

224

Van Lang Formation [10] comprises in its lower part calcareous sandstone and siltstone grading upward to clay shale, siltstone, sandstone, coaly shale and fat coal seams; 400-600 m thick. The lower part yields bivalves, such as Gervillia cf. inflata, Unionites damdunensis, Bakevellia cf. magnissima, while the upper part yields plant remains, such as Clathropteris meniscioides, Dictyophyllum sp., Pterophyllum cf. intermedium, Lonchopteris virginensis. The formation has been dated as Norian-Rhaetian. In the other basins where Triassic sequences occur, the Triassic section is strongly curtailed, and has the same common characteristics as the above-described sequences. Only in Quang Ninh Basin (2, Fig.l) the Norian-Rhaetian coal-beating Hon Gai Formation [7] is very thick (1500-2000 m) bearing thick anthracite seams, the biggest of which has a thickness up to 60 m. The most characteristic species of the Hon Gai Flora are as follows: Dictyophyllum nathorstii, Clathropteris meniscioides, Taeniopteris spathulata, T. jourdyi, Neocalamites hoerensis, Pterophyllum contiguum, Goeppertella microloba, Asterotheca cottoni, Thaumatopteris remauryi, Todites shensiensis, Baiera guilhaumati, Glossopteris indica, etc. 2.2. Northwest Viet Nam

In NW Viet Nam, Triassic sediments are largely distributed in the Song Da (Black River) Basin (3, Fig. 1), where the depositional accumulation during the Triassic occured in 3 cycles: 1) Induan - early Ladinian; 2) late Ladinian- Carnian; and 3) Norian-Rhaetian. The most characteristic features of the Triassic in this basin strongly differ from those of NE Viet Nam. They are as follows: 1) the Anisian is represented by only limestone, lying conformably upon the Lower Triassic; 2) the Carnian is composed of marine sediments bearing deep-dwelling halobiids; and 3) the lower part of the Norian-Rhaetian coal-beating formation is characterized by marine beds beating Norian ammonites. The Lower Triassic of the Song Da Basin is represented by the Co Noi Formation, but in tl~e areas where volcanics are well developed in the lower part of the section it has been divided into two formations, namely the Vien Nam of Induan age, and the Tan Lac of Olenekian age. Co Noi Formation [7] is composed of basal conglomerate, tuffaceous sandstone and siltstone, interbedded with mafic volcanics, clay shale grading upward to marl, clay shale, or locally, to clayish limestone of motley colour; 750-1200m thick. The siltstone of the lower part contains Claraia griesbachi, C. stachei, Eumorphotis inaequicostata, etc. of Induan age, whilst marl and siltstone of the upper part contain Tirolites cf. idrianus, Anakashmirites nivalis, Plococeras sp. of Olenekian age, together with Gervillia exporrecta, Unionites fassaensis, etc.. Based on these fossils the formation has been dated as early Triassic. Vien Nam Formation [11] consists of basalt, trachyte, porphyritic trachyte, rhyotrachyte, porphyritic rhyolite, tuffaceous agglomerate and felsitic tufts; 950-1100 m thick. Basal beds of the formation lie unconformably upon the Upper Permian coal-bearing formation. The Vien Nam Formation has been supposedly assigned to Induan based on its conformable relationship with the overlying Tan Lac Formation. Tan Lae Formation [11] comprises tuffaceous sandstone, tuffite, red siltstone, sandstone, greenish marl, clayish limestone; 800-900 m thick. The marl yields Tirolites sp., Neoschizodus laevigatus elongatus, Costatoria r Entolium discites microtis dating the formation as Olenekian. The Middle Triassic of the Song Da Basin has been divided into 3 formations.

225

Dong Giao Formation [7] lying conformably upon Lower Triassic sediments is formed only by limestone, locally bearing some lenses of marl in its upper part; 1200-1800m thick. From the lower part of the Formation brachiopods have been collected, such as Mentzelia mentzelii, Coenothyris vulgaris and the bivalve ?Pseudomonotis michaeli, and from the middle and upper part--ammonoids Cuccoceras cuccense and then, Paraceratites subtrinodosus and bivalves Daonella elongata and D. sturi. The whole faunal assemblage dates the formation as Anisian. Nam Tham Formation [12] is composed of marl, clay shale, siltstone, sandstone with some interbedded limestone; 400-700m thick. These rocks furnish Protrachyceras villanovae, P. costulatum, Rimkinites tonkinensis and bivalves Daonella lommeli, D. indica, Zittelihalobia planicosta, Posidonia wengensis, etc. of early Ladinian age. Muong Trai Formation [Tran Dang Tuyet in 11], lying unconformably upon older rocks, comprises sandstone, clay shale, siltstone with, locally, thick lenses of limestone; 600-800m thick. These sediments yield two faunal assemblages. The shallow-water fauna includes Trigonodus sandbergeri, T. trapezoidalis, Costatoria goldfussi, Cassianella gryphaeata etc., whilst the deep-dwelling fauna comprises Daonella indica, Zittelihalobia comata, Posidonia wengensis of Ladinian age. The Upper Triassic in NW Viet Nam has been divided into two formations, locally, into three. Nam Mu Formation [7], lying conformably upon the Muong Trai Formation, is composed mainly of clay shale, which is locally transformed into platy schist, grading upward to sandstone, siltstone and clay shale; 900-1200m thick. The clay shale furnishes Halobia austriaca, H. talauana, H. substyriaca, Zittelihalobia superba together with Margaritropites fongthoensis, Anatomites sp. of Carnian age. Pac Ma Formation [13] consists of coral reef limestone; 120-200 m thick, marking the regressive phase of the late Ladinian - Carnian depositional cycle in the Song Da Basin. It contains corals, such as Isastrea profunda, Montlivaultia norica together with terebratulids Rhaetina bamaensis, R. complanata, Aulacothyropsis bisinuata and the Carnian ammonoid Tornquistites sp.. The formation has been assigned to late Carnian. It has a very limited distributive area. Suoi Bang Formation [7] lying unconformably upon all older sediments is composed of basal conglomerate, sandstone, siltstone, clay shale with interbeds of coquina grading upward to siltstone, coaly shale, clay shale, sandstone with thick coal seams; 800-1000 m thick. Classical Rhaetian bivalves of Europe and of the Napeng Beds (Myanmar) like Gervillia praecursor, Trigonia zlambachiensis, Triaphorus angulatus, Costatoria (Napengocosta) napengensis, Thracia prisca etc. have been found in the lower part of the formation together with Norian ammonoids Juvavites magnus, Cyrtopleurites bicrenatus, Parathisbites sopcopensis, Norian halobiids Halobia norica, H. distincta etc. and many endemic genera, such as Songdaella, Mesoneilo, Langvophorus, Mesopinna. This mixed fauna has been regarded as Norian based on ammonoids. The upper part of the formation yields remains of the Hon Gai Flora, such as Clathropteris meniscioides, Taeniopteris jourdyi, Glossopteris indica, together with some bivalves from interbeds of marine facies, such as Gervillia cf. inflata, Vietnamicardium altum, etc.. This flora and fauna have been regarded as of Rhaetian age. Thus, the Suoi Bang Formation has been dated as Norian-Rhaetian. It grades continuously upward to Jurassic continental red beds.

226

In other Triassic-bearing basins of NW Viet Nam the Triassic section is strongly curtailed, and has the same characteristics in common with the above sections. 2.3. North of Central Viet Nam In the North of Central Viet Nam, Triassic sediments are largely exposed in the Sam Nua Basin (4, Fig. 1). In this area the section type of Triassic has common characters with Triassic sequences of NE Viet Nam, i.e. Anisian begins a depositional cycle with volcanogenic rocks. However, the Triassic section is shortened with 2 cycles: 1) Middle Triassic ; and 2) NorianRhaetian. Middle Triassic in the studied region of N Central Viet Nam lies unconformably upon Paleozoic formations. It has been divided into three formations. Dong Trau Formation [7] is composed of basal conglomerate, tuffaceous sandstone, thick members of rhyodacite, porphyritic rhyolite, quartz porphyry and their tufts grading upward to siltstone, clay shale and sandstone; 1000-1200 m thick. Clay shale lying upon volcanics yields Paracrochordiceras sp., Acrochordiceras cf. fischeri, Balatonites cf. balatonicus, Cuccoceras annamiticum together with bivalves Daonella laluensis, Posidonia mimer, etc.. The marl of the upper part of the formation contains Paraceratites cf. trinodosus. These faunas date the formation as Anisian. Hoang Mai Formation [7] consists only of limestone, 100-500 m thick, locally containing in abundance brachiopods, such as Adygella hoangmaiensis, Holcorhynchia bogumilorum, Aulacothyris angusta, and ammonoids Leiophyllites cf. laevis, Beyrichites cf. migayi. The formation has been assigned to late Anisian. Quy Lang Formation [7] comprises siltstone, sandstone, clay shale and marl; 1200-1500 m thick. These rocks furnish Trigonodus sandbergeri, T. trapezoidalis, Costatoria goldfussi, C. ngeanensis, Hoernesia magnissima dating the formation as Ladinian. The Norian-Rhaetian coal-bearing Dong Do Formation [7] consists of a basal conglomerate, sandstone, siltstone, coaly shale and thin coal seams; 600-700 m thick. The siltstone yields rare remains of Unionites damdunensis, Modiolus sp., but the coaly shale contains many remains of the Hon Gai Flora, such as Clathropteris meniscioides, Taeniopteris jourdyi, Cycadites saladini, Czekanowskia sp. In the Nong Son Basin, situated in the southern part of the studied area, the first cycle consists only of Anisian volcanogenic sediments, 1500-2000 m thick, described as Song Bung Formation [14]. It underlies unconformably the Norian-Rhaetian Nong Son coalbearing Formation [15], 1000-1200 m thick. The Song Bung Formation contain rare Anisian bivalves, such as Palaeoneilo yanjiensis, Neoschizodus sp., whilst the Nong Son Formation yields many species of the Hon Gai Flora, such as Dictyophyllum nathorsti, Clathropteris platiphylla, Baiera guilhaumati etc.. 2.4. South Viet Nam In South Viet Nam thin sequences of Triassic sediments occur in two basins; they are the Ta Thiet Basin situated in the east of the region, and the Hon Nghe Basin situated in the Gulf of Thailand. The Triassic section of Ta Thiet Basin has the same aspect as that of NE Viet Nam, i.e. Anisian consists of volcanogenic beds, whilst the Triassic section of Hon Nghe Basin is similar with that o f N W Viet Nam, i.e. the Anisian is represented by limestone.

227 In the Ta Thiet Basin (5, Fig.l), there are two Triassic depositional cycles: 1) Lower Triassic; and 2) Anisian. The Lower Triassic of this basin has been described as the Song Sai Gon Formation [16]. It includes calcareous sandstone, siltstone, clay shale, sandstone; 700 m thick. The calcareous sandstone of the basal member yields Metotoceras phumyi, Ophiceras cf. commune, Claraia stachei, Eumorphotis cf. inaequicostata; the siltstone higher in the section contains Gyronites sp.; whilst siltstone of the upper part of the formation furnishes Anasibirites sp.. These fossils form the basis for the dating of the formation, which lies unconformably upon Upper Permian limestone. Chau Thoi Formation [16] cOnsists of basal conglomerate lying The Anisian unconformably upon Lower Triassic sediments, followed by rhyolitic tuffs, tuffaceous sandstone grading upward to sandstone, clay shale, siltstone; 400 m thick. The clay shale yields Bulogites multinodosus, Balatonites cf. balatonicus, Gymnotoceras cf. blakei, Daonella lindstroemi dating the formation as Anisian. In the Hon Nghe Basin (6, Fig.l), Triassic sequences are represented only by the Middle Triassic cycle, including two formations. Mirth Hoa Formation [17] is composed only of grey limestone; 200m thick, bearing foraminiferas, such as Diplotremina astrofimbriata, D. cf. baoi, Endothyranella aff. E. hoangmaiensis dating the formation as Anisian. Its lower and upper boundaries are unknown at present. Hon Nghe Formation [16] includes clay shale and siltstone; 200 m thick, yielding Daonella cf. moussoni, Posidonia wengensis of Ladinian age. Its lower and upper boundaries are also unknown. 2.5. Upper Laos In Upper Laos there are also two basins where Triassic beds have been reported to be found: the Nam Beng Basin in the west and the Sam Nua Basin in the south. During the recent decades there has not been any stratigraphic study in the Nam Beng Basin (7, Fig.l). According to French geologists [18], Lower Triassic shale bearing Xenodiscus salomoni and Pseudosageceras cf. clavisellatum was found in Saniabouli, S of Luang Prabang. There were no data on Middle Triassic of this region, but Carnian was described with clay shale and marl bearing a deep-dwelling fauna in the basin of Nam Beng River, W of Luang Prabang [19]. This fauna consists of halobiids, such as Halobia cassiana, "H." comata, and ammonoids Discotropites cf. sandlingensis. In this area limestone belonging to the coral reef facies was also found with coral Thecosmilia sp. and brachiopod

"Aulacothyris" inflata. Norian-Rhaetian shale was described also near Luang Prabang, at Don Tien and Sang Hai, with ammonoid Tibetites sp. [19], whilst in the basin ofNam Beng River Norian-Rhaetian was described as Con Tagne Conglomerate bearing the Napeng Fauna with Burmesia lirata, Thracia prisca, Palaeocardita singularis mixed with the European Rhaetian species Rhaetavicula contorta, etc.. In the Laotian part of the Sam Nua Basin (8, Fig.l), the sequences are similar with those of its Vietnamese part. They are composed also of four formations. Nam Sam Formation [20] is composed of porphyritic rhyolite, rhyodacite, porphyritic felsite and their tufts grading upward to siltstone, clay shale and sandstone, 1200-1400 m

228 thick. Fine-grained rocks yield ammonoids Cuccoceras sp., Acrochordiceras sp., Paraceratites trinodosus, Kellnerites samneuaensis together with bivalves Costatoria curvirostris, Posidonia aequilatera, etc. dating the formation as Anisian. Ban 0 Formation [20] includes only limestone bearing different endemic terebratulids, such as "Holcothyris" laosensis, "Aulacothyris" dussaulti, "Zeilleria" pentagona, "Z " intermedia, which have not been revised recently. The Ban O limestone has been dated as late Anisian.

Sang Phou Formation [To Van Thu in 21] comprises siltstone, clay shale, sandstone with interbeds of limestone, 700-800 m thick, bearing Trigonodus trapezoidalis, 7". tonkinensis, Costatoria cf. goldfussi etc., well-known in Ladinian formations of Viet Nam. Nam Neun Formation [Nguyen Dzuy Khanh in 21] is coal-bearing including basal conglomerate, sandstone, siltstone, clay shale, coaly shale and coal seams, 600-800 m thick. These rocks yield Costatoria (Napengocosta) napengensis, Thracia prisca, Protocardia contusa, Zittelihalobia obrutchevi, etc. and plant remains of the Hon Gai Flora. Its basal conglomerate unconformably covers limestone of the Ban O Formation. So, these two basins of Upper Laos have two different Triassic section types. The section of Triassic in Nam Beng Basin is close to that of NW Viet Nam because of the marine facies bearing deep-dwelling halobiids during Carnian time. It distinctly differs from the Triassic sequences of Sam Nua Basin, where Carnian is absent. 2.6. North Cambodia In North Cambodia (9, Fig.l), Triassic sediments have been reported to be present in Rovieng with tuffaceous sediments: shale bearing Balatonites cf. zitteli of middle Anisian age. In Plouk greenish sandstone is exposed, yielding Paraceratites cf. trinodosus, Beyrichites khanicofi of late Anisian age [22]. These very little data allow to compare the Triassic section of this territory with that of the Ta Thiet Basin of S Viet Nam on both lithologic and paleontological aspects. 2.7. North Thailand In Thailand, Triassic sequences are distributed in some sedimentary basins, of which the Lampang-Phrae Basin of N Thailand (10, Fig.l) has the most complete Triassic section. In this area, Triassic sequences in comparing with those distributed in eastern countries (Laos, Viet Nam) lack the coal-beating formation, which lies in their upper part. But the characteristics of the sediments have many common features with the sequences ofNW Viet Nam, i.e. Anisian is represented by carbonate rocks, and there is a gap in the depositional process in the mid of Ladinian. These sequences have been described as the Lampang Group which includes seven formations [23, 24]. Phra That Formation is composed of tuffaceous siltstone, quartzitic sandstone, arkosic sandstone, shale, mudstone with interbeds or lenses of limestone; 650m thick. The lower part of the formation yields Eumorphotis multiformis of Induan age, whilst the upper part contains the Costatoria assemblage with: Elegentinia elegans, Bakevellia cf. exporrecta, Costatoria goldfussi mansuyi. The formation has been assigned to the Lower Triassic. Pha Khan Formation consists of limestone with calcareous mudstone and shale in the lower part; 500m thick. The limestone contains the Anisian ammonoid Hollandites cf.

229

roxburgi together with brachiopods Mentzelia mentzelii, Lingula cf. tenuissima (at Ban Hua Sua). The formation can be assigned to the Anisian. Hong Hoi Formation is composed of mudstone, quartzite-like sandstone, siltstone, greywacke, calcareous mudstone and interbedded limestone; 1350m thick. The lower part of the formation contains well-known Ladinian bivalves, such as Daonella indica, D. cf. bulogensis (at Ban Pang La). A bit higher in the section another fauna assemblage has been found with Paratrachyceras cf. regoledanum, Joannites sp., Daonella sp. nov., Posidonia cf. cycloides (at Huai Mae Huat), and Protrachyceras cf. longobardicum, Posidonia wengensis (at Ban Tha Si). Based on this fauna, the formation has been dated as Ladinian. Doi Long Formation includes limestone with interbedded dolomite; 200m thick. The limestone yields abundant Trigonodus costatus, which dates the formation as late Ladinian. Pha Daeng Formation is characterized by red continental beds lying unconformably upon older formations. It is composed of conglomerate, pebble-beating sandstone, red-coloured siltstone, mudstone and calcareous cross-bedded sandstone; 850 m thick. The siltstone yield s Trigonodus cf. problematicus, Liotrigonia sp. indet, and Zittelihalobia comata (at Kaeng Luang). Based on this fauna, the formation has been assigned to the uppermost Ladinian. Kang Pla Limestone comprises grey limestone, 80-330 m thick, bearing Zittelihalobia comata, Spiriferina sp. together with corals, such as Thecosmilia aff. T. oppeli, Montlivaltia sp. and Margarosmilia sp. (at Ban Pha Khan). These fossils date the formation as early Camian. Mae Thang Formation is composed of shale and siltstone, 800-1200 m thick. The shale from the lower part of the formation contains Halobia charlyana, H. talauana, H. deningeri, Juvavites cf. idenburgi (at Ban Pha Kho) of Camian age. Shale from the upper part of the formation yields Halobia styriaca, Palaeocardita singularis, Schafhaeutlia cf. rostratus (at Amphoe Ngao). Siltstone of the uppermost beds contains Indopecten seinaamensis, Palaeocardita trapezoidalis and Schafhaeutlia sp. (at Ban Mae Saliam) of Norian age. Based on the above-cited fauna, the formation has been dated as late Carnian - Norian. In other basins of Thailand the Triassic section is strongly shortened, and has not been studied in detail yet. 2.8. Central Belt of Malaysia In the Central Belt of Malaysia, Triassic sediments have the most complete section in the Gua Musang area (Kelantan) (11, Fig.l). In these sequences there is also not an Upper Triassic coal-bearing formation as in N Thailand, and the Anisian is also characterized by carbonate sediments. But, there is not a gap during the depositional process of Triassic. The sequences have been divided into two formations [25]. Gua Musang Formation is composed mainly of limestone with interbeds of shale and volcaniclastics; about 900 m thick. The lower part of the formation contains Claraia intermedia multistriata, C. griesbachi concentrica of Induan age. In the middle part there has been found the Owenites-Arctoceras-Parannanites-Prosphingites ammonoid assemblage together with the conodont Neospathodus conservativus of Olenekian age. In the upper part fossils have not been found. This formation has been regarded as lying conformably upon Permian beds. In its turn it conformably underlies Ladinian beds of the Gunong Rabong Formation. It has been dated as Induan-Anisian.

230

Gunong Rabong Formation includes in its lower part an intercalation of limestone, sandstone, conglomerate and shale, and in its upper part, sandstone and shale; about 920 m thick. The shale yields Daonella cf. indica in the lower part, and Paratrachyceras sp., Posidonia cf. kedahensis in the upper. Based on this fauna, the formation has been dated as Ladinian-Carnian. It is worthy to note the Triassic section in the Kodiang area (Kedah), where it is characterized only by limestone, described as Kodiang Limestone. Its lower beds yield earliest Triassic conodonts, such as Neospathodus dieneri, N. cf. waageni, N. pakistanensis. In the middle of the section early Anisian conodonts have been found, such as Neogondolella bulgarica, Gladigondolella tethydis, Neospathodus kockeli. The upper part of the formation contains Ladinian - early Carnian conodonts, such as Neogondolella polygnathiformis, N. excelsa, N. bulgarica. The formation has been dated as Induan-Carnian. The Triassic section in the other areas is more or less incomplete. 2.9. Myanmar In Myanmar the Triassic sequences are fully exposed in the Shan States (12, Fig. 1). They have particular features, which have not been seen in any Indochinese countries. This includes following characteristics: 1) Lower and Middle Triassic form the upper part of a continuous section of dolomite, the lower part of which consists of Permian sediments; 2) NorianRhaetian sediments are composed of marine sediments. The Lower and Middle Triassic have been described as the upper part of the Shan Dolomite Group and the Upper Triassic--as the lower part of the Namyau Group [26]. The Upper Shan Dolomite Group begins with thinly interbedded shale and limestone, bearing early Triassic ammonoids, such as Glyptophiceras, Vishnuites, Ophiceras, Owenites, Kashmirites, etc.. These sediments grade upward to dolomite. The total thickness of the group reaches 1270 m. The dolomite yields rare foraminiferas Glomospirella irregularis. The described group has been assigned to the Lower Triassic - Lower Carnian. The Lower Namyau Group is composed of the Pangno Evaporite Member and the Napeng Member. The first consists of gypsum, anhydrite and salt, 220 m thick. It lies unconformably upon Shan Dolomite, and may be assigned to Upper Carnian. The second begins with limestone beds grading upward to siltstone; 400 m thick. It contains the wellknown Napeng Fauna, consisting of European Rhaetian bivalves, such as Rhaetavicula contorta, Gervillia praecursor, Grammatodon lycetti together with many endemic taxa, which occur in Norian formations of the Indochinese region and South China, such as Burmesia lirata, Costatoria (Napengocosta) napengensis, Palaeocardita singularis, etc.. This member has been assigned to the Norian-Rhaetian. In the Kamawkale Gorge area of the Tenasserim Basin, Triassic sequences have been described as the Mae Moei Group. The lower part of the group is composed mainly of siltstone with interbeds of sandstone; 840 m thick, bearing in its upper part a Carnian (?) fauna with Halobia? sp., Protocardia sp., Gonodon aff. mellingi. It has been supposedly assigned to Lower Triassic - Carnian. The upper part has been named as the Kamawkale Limestone, including dolomite, grading upward to an intercalation of limestone and dolomite, about 1000 m thick. The basal beds of this unit yield brachiopods, such as "Rhynchonella" bambanagensis, and Stylophyllopsis thaungyinensis. The whole unit has been assigned to the Norian-Rhaetian.

231

All the above-described materials on the development of Triassic sequences in Indochina are s u m m a r i z e d in the Table 1, where the formations are correlated one with another in accordance with their paleontological data. The faunal and floral assemblages from different Triassic basins o f the Indochina Peninsula have m a n y c o m m o n genera and species [27]. Some of them are endemic for m a n y areas of the region, such as Prolaria, Datta, Burmesia, Langvophorus, Langsonella, Costatoria (Napengocosta), etc.. M a n y endemic species have been found in alone basins. But, in all assemblages, from Early to Late Triassic, there exist a lot of cosmopolitan taxa, especially those of ammonoids, which make the interregional correlation of Triassic sediments easy. Based on paleontological assemblages from the sequences of different basins, a Triassic fossil zonation of the Indochina Peninsula has been presented (Table 2).

Acknowledgement: The author would like to express his deep thanks to Prof. Yin Hongfu for his encouragement and help in the realization o f this study.

REFERENCES 1. R. Zeiller, Examen de la flore fossile des couches de charbon du Tonkin. Ann. Mines, 8e ser., 11 (1882) 299-352, Paris. 2. R. Zeiller, Sur la flore des charbons du Tonkin. C.R. Acad. France, 95 (1882) 194-196, Paris. 3. R. Zeiller, Resume de l'examen de la flore des couches de charbon du Tonkin. Bull. Soc. Geol. France, 3/XI (1883) 456-461, Paris. 4. C. Diener, Note sur deux especes d'Ammonites triasiques du Tonkin. Bull. Soc. Geol. France, 3e ser., 24 (1896) 882-886, Paris. 5. Newton, Notice on some fossils from Singapore discovered by J.Scrivenor, geologist of the Federated Malay States. Geol. Magazine, N.S. 13 (1906) 487-496, London. 6. M. Healey, The fauna of the Napeng Beds or the Rhaetic beds of Upper Burma. Palaeont. Indica, N.S., 2/4 (1908) 98 pp., New Dehli. 7. A.E. Dovzhikov (ed.), Geology of North Viet Nam, Gen. Dept. Geol., Ha Noi, 1965, 665 pp. (in Russian). 8. Vu Khuc, Stratigraphy of the Triassic in Viet Nam, In Geol. & Min. Res. of countries of Asia, Africa and Lat. America, (1980) 34-44, Univ. Lumumba, Moscow (in Russian). 9. Nguyen Kinh Quoc et al., New data on the geology of Binh Gia map sheet group. Proc. 2nd Conf. Geol. Indochina, 1 (1991) 71-78, Ha Noi. 10. Ta Hoang Tinh & Pham Dinh Long, New data on coal-bearing sediments and the Ha Coi Formation in Thai Nguyen area. J. Geology, 53 (1966) 20-25, Ha Noi (in Vietnamese). 11. Phan Cu Tien (ed.), Problems of geology o f N W Viet Nam. Sci. & Techn., Ha Noi, 1997, 358 pp. (in Vietnamese). 12. Nguyen Xuan Bao, New data on the geological structure of the Van Yen area. J. Geology, 91-92 (1970) 63-67, Ha Noi (in Vietnamese). 13. Vu Khuc, Again on the age of the Pac Ma Red Limestone. J. Geology, 73 (1967) 9-13, Ha Noi (in Vietnamese). 14. Nguyen Van Trang (ed.), Geological map of Viet Nam on 1:200 000: Hue - Quang Ngai sheet series. Geol. Surv. Viet Nam, Ha Noi, 1996. 15. R. Bourret, La chaine Annamitique et le plateau du Bas Laos t~ l'ouest de Hue. Bull. Serv. GDol. Indochine, 14/5 (1925) 110 pp., Hanoi. 16. Bui Phu My & Vu Khuc, On the recently discovered Triassic sediments in South Viet Nam. J. Earth Sci., 2/2 (1979) 3-7, Ha Noi (in Vietnamese).

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17. Nguyen Xuan Bao, In Geological map of Viet Nam on 1:200 000: Nam Bo Plain sheet series. Geol. Surv. Viet Nam, Ha Noi, 1997. 18. J. Fromaget, Sur l'existence du Trias inferieur ~t faciIs oceanique au sud de Luang Prabang et sur la paleogeographie de l'Asie sud-orientale A cette epoque. C.R. Acad. Sci. France, 201 (1935) 284-286, Paris. 19. J. Fromaget, Le Trias dans la partie nord-ouest du synclinal de Sam-Neua (Tonkin et Laos). C.R. Acad. Sci. France, 199 (1934) 962-964, Paris. 20. L. Dussault, Exploration geologique dans la province de Sam Neua (Laos). Bull. Serv. Geol. Indoch., 9/2 (1920) 60 pp., Hanoi. 21. Vu Khuc, The Triassic in Viet Nam and adjacent areas. ES Atlas of Stratigraphy 9 (1990) 48-53, UNESCO, New" York. 22. E. Saurin, Etudes geologiques sur l'Indochine du Sud-Est (Sud Annam, Cochinchine, Cambodge oriental). Bull. Serv. Geol. Indochine, 22/1 (1935) 419 pp., Hanoi.23. C. Chonglakmani & J. GrantMackie, Biostratigraphy and facies variation of the marine Triassic sequences in Thailand. Proc. Intern. Symp. Biostratigraphy of mainland SE Asia (1993) 97-124, Chiang Mai. 24. P. Charusiri et al., Detailed stratigraphy of the Ban Thasi area, Lampang, northern Thailand: Implications for paleoenvironments and tectonic history. Proc. Intern. Symp. Stratigraphic correlation of SE Asia (1994) 226-244, Bangkok. 25. Khoo Han Peng, Burma. In Triassic of Asia, Australia and the Pacific. ES Atlas of Stratigraphy 13 (1988) 23 pp., UNESCO, New York. 26. Thein Myint Lwin, Malaysia. In Triassic of Asia, Australia and the Pacific. ES Atlas of Stratigraphy 13 (1988), UNESCO, New York. 27. Vu Khuc and Dang Tran Huyen, Triassic correlation of the Southeast Asian mainland. J. Palaeogeography, Palaeoclimatology, Palaeoecology, 143 (1998) 285-291, Elsevier.

Table 2. Triassic fossil zonation of the Indochina Peninsula Co~n scale

Ammonoids

T3r

Gervillia inflata- Unionites damdunensis Parathisbites

T3n

D i c t y o p h y l l u m - Clathropteris

Burmesia lirata Gervillia p r a e c u r s o r -

Juvavites - Cyrtopleurites Margaritropites

T3c Discotropites

T31

Others

Bivalves

Protrachyceras - Rimk mites

Kellnerites

Halobia norica Rhaetina - Laballa - Sinucosta

Halobia talauana Zittelihalobia superba

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Zittelihalobia

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Daonella elongata -

Holcorhynchia - Aulacothyris

D. lindstroemi

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Paraceratites Balatonites Tirolites - Columb ites

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Eumorphotis venetiana,

Naticella costata - Worthenia turbo

Unionites fassaensis, Flemingites - Paranorites

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Costatoria p r o h a r p a -C. curvirostris

Gervillia exporrecta

Gyronites - K o n m c k ites

Claraia stachei - C. vietnamica

Ophiceras commune

Claraia w a n g i - C. stachei

Neospathodus dieneri - N. waageni

This Page Intentionally Left Blank

Persian-TriassicEvolution of Tethys and WesternCircum-Pacific H. Yin, J.M. Dickins, G.R. Shi and J. Tong (Editors) e 2000 ElsevierScienceB.V. All rightsreserved.

235

T h e M a r i n e T r i a s s i c of A u s t r a l a s i a n and its i n t e r r e g i o n a l c o r r e l a t i o n H. J. CAMPBELL a and J.A. GRANT-MACKIE b a Institute of Geological and Nuclear Sciences Ltd., PO Box 31-312, Lower Hutt, New Zealand. b Department of Geology, The University of Auckland, Private Bag 90219, Auckland, New Zealand. Marine Triassic sequences are rare along the continental margins of all oceans within the Southern Hemisphere and particularly so in the Atlantic and Indian Oceans. They are also rare within the southern continents. Marine Triassic sequences are only preserved along the west and southwest Pacific margins of what was eastern Gondwanaland. This paper summarises what is known of these rocks and in particular the marine Triassic strata of Australasia (Fig. 1): New Zealand, New Caledonia, Australia, Papua New Guinea and eastern Indonesia. The relevant fossiliferous strata are described in terms of terranes, their known faunal content, biostratigraphic age control and correlations, both inter-terrane and regional.

1. NEW ZEALAND Sedimentary rocks of Triassic age are widespread in New Zealand, and are recognised within at least seven tectonostratigraphic units or terranes, but well exposed, readily mappable and stratigraphically coherent fossiliferous successions are confined to one of these terranes, namely the Murihiku Terrane. Sequences in all terranes are almost exclusively marine or marginal marine. Strata within the Murihiku Terrane provide the basis for biostratigraphic subdivision and hence recognition of local New Zealand stages [1, 2, 3]. Two series and seven stages are recognised in the Triassic.

1.1. Tectonostratigraphic framework of New Zealand Two major tectonostratigraphic divisions are recognised in New Zealand (Fig. 2). These are the Western Province and the Eastern Province, and each consists of a number of terranes [4]. All Eastern Province terranes were metamorphosed during Late Jurassic - Early Cretaceous time. Western Province terranes were variably metamorphosed in the Paleozoic and again in the Mesozoic. Correlation between Eastern Province and Western Province metamorphic events, if any, is unclear.

1.1.1. Western Province The Western Province [5], bordering the Tasman Sea, is essentially a fragment of Australian continental foreland comprising distinct Paleozoic terranes (Buller, Takaka). This 'province' constitutes the dispersed New Zealand segment of autochthonous Gondwanaland.

236

The Western Province is notable in several respects. It includes the oldest known rocks in New Zealand which are of Middle Cambrian age, and it is host to extensive plutonic rocks of Cretaceous age that are conspicuously absent within the Eastern Province [6].

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237

Figure 2. Simplified basement map of New Zealand showing distribution of the major tectonostratigraphic entities" provinces, terrane assemblages, terranes and their fault boundaries. Key components of the modem tectonic setting are also shown.

238

A fragmentary record of a Gondwanaland cover sequence with strong eastern Australian affinities is preserved within the Western Province, and this includes Devonian, Permian and Triassic successions and Jurassic dolerite of Ferrar Magmatic Province affinity [7, 8]. There are two known Triassic units within the Western Province, namely the Walker Quartzite (Parapara Group) and Topfer Formation. Both units have very limited (< 10 km 2) outcrop area and consist of fluvial or marginal marine quartzose sediments. On the basis of palynomorphs, Topfer Formation is Triassic in age [9, 10]. There is a suggestion that several floras are preserved, ranging in age from Early to Late Triassic. The Walker Quartzite is thermally metamorphosed and unfossiliferous but contains detrital zircons suggesting that it cannot be older than Early Triassic [ 11 ]. The Western Province is separated from the Eastern Province by the Median Tectonic Zone [12], a belt of long-lived subduction-related magmatic rocks that have recently been interpreted as a Cordilleran batholith [ 13], evidence of a major crustal boundary. 1.1.2. Eastern Province

The Eastern Province [4] is an assemblage of accreted allochthonous terranes making up northern New Zealand and the Pacific margin in the south. Two distinct groupings of terranes are recognised on the basis of gross composition. The first includes three terranes of island arc association, dominated by volcaniclastic sediment. These are the Brook Street, Dun Mountain - Maitai and Murihiku Terranes, referred to here as the Central Arc Terranes (= Hokonui Assemblage [14]). They occupy central position between the Western Province and the second grouping of Eastern Province terranes herein referred to as the Torlesse Superterrane (=Te Anau and Alpine Assemblages [14]). Previous use of the name 'Torlesse' was as a terrane with subterranes [15]. The name 'Torlesse' is retained but now at a higher level, hence Torlesse Superterrane. All previous Torlesse subterranes are accorded terrane status. The Caples and Waipapa Terranes are also included within the superterrane. The Torlesse Superterrane is an assemblage of five terranes that includes vast areas and volumes of predominantly quartzofeldspathic sediment that must have been derived from dominantly terrigenous granitoid sources located outside the New Zealand sector but still within eastern Gondwanaland. These terranes include Caples, Rakaia, Waipapa, Pahau and Waioeka Terranes. The Waipapa Terrane also includes quartzofeldspathic sediment but is characterised by lithologies of oceanic association: chert, hemipelagite and basalt. Within the Eastern Province, fossiliferous marine Triassic rocks are known from the Dun Mountain- Maitai, Murihiku, Caples, Rakaia, Pahau and Waipapa Terranes (Fig. 3). 1.1.3. Dun M o u n t a i n - Maitai Terrane

This comprises a six-kilometre thick, moderately metamorphosed volcaniclastic sedimentary succession, the Maitai Group, resting in primary depositional contact on the Early Permian Dun Mountain Ophiolite. The lower 1,000-1,500 m of the Maitai Group is of Late Permian age, but the bulk (4,500-5,000 m) is now known to be of Early to Middle Triassic age. Sparsely fossiliferous and largely made up of redeposited sediments, the Maitai Group contains three undescribed ammonoid faunas of Induan and Olenekian age [16]. No other identifiable fauna is associated with these ammonoids. Induan shelly fossils have not been recognised from any other terrane within New Zealand. The Maitai Group Triassic is almost devoid of carbonate lithologies and cherts and black shales are absent. A Permian-Triassic boundary has been recognised on the basis of organic

239

~5~3Cisotopic signature [ 17], near the base of the Little Ben Sandstone, an unfossiliferous unit that overlies fossiliferous Permian Tramway Sandstone. The Kaka Point Structural Belt exposed on the Otago coast near Kaka Point, is the youngest sequence attributed to the Dun Mountain-Maitai Terrane. These rocks constitute the least metamorphosed Triassic rocks in New Zealand [18], and include well-preserved faunas with brachiopods, bivalves, gastropods, ammonoids, radiolarians and rare conodonts [ 19].

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240 1.1.4. Murihiku Terrane

The Murihiku Terrane is the least structurally deformed and stratigraphically most coherent of the New Zealand basement terranes. It is weakly metamorphosed (up to zeolite facies) and includes a thick succession of volcaniclastic sediment spanning Early Triassic to Late Jurassic and possibly Early Cretaceous time. It represents a long-lived arc-related basin, now detached and presumed to be remote from the original location of the volcanic sources [20], although the Median Tectonic Zone (Median Batholith) may be a possible source. The Triassic succession is about 7,000 m thick and has been subdivided into local series and stages [1, 2, 3] as follows, from youngest to oldest: Balfour Series: Otapirian, Warepan, Otamitan and Oretian Stages; Gore Series: Kaihikuan, Etalian and Malakovian Stages. The Murihiku Triassic contains a diverse and relatively rich fossil record but is notable for the complete absence of limestones, cherts and black shales. It contains numerous coquina shellbeds and some calcareous siltstones but is otherwise dominated by clastic sediments: siltstone, sandstone, conglomerate, and tufts. The fossil record includes palynomorphs [21 ], plants [22], foraminiferans [23], radiolarians, hydrozoans [24], conulariids [25], bryozoans and tabulates [26, 27], brachiopods [28, 29, 30], nautiloids, ammonoids [3], gastropods, bivalves [3], ostracods [30], marine vertebrates [31], conodonts, tube fossils and trace fossils. Biostratigraphic correlations based largely on ammonoids, but also brachiopods, bivalves, rare conodonts and radiolarians, indicate Anisian to Rhaetian representation of Triassic time within the Murihiku Terrane [2, 3]. The status of isolated Olenekian faunas is under review. Detailed biostratigraphic research has recognised a number of major disconformities within the Murihiku succession [2, 3, 21, 28]. These 'boundaries' coincide with the bases of local stages and denote significant non-representation of Triassic time. For instance, the local Etalian-Kaihikuan stage boundary represents much of Ladinian time. Only the topmost Sutherlandi Zone appears to be represented within the Murihiku. Similarly, the KaihikuanOretian boundary represents much, if not all, of Carnian time. Norian time is particularly well represented within the Murihiku Terrane, both in terms of fossils and stratigraphic thickness. The Rhaetian is well represented in terms of stratigraphic thickness, but has only moderate fossil diversity. There is good exposure of a Triassic-Jurassic boundary succession, but lowest Jurassic (Planorbis Zone) indicator fossils have yet to be recognised. Ongoing research is testing the hypothesis that the onset of Jurassic time within the Murihiku occurs within the late Otapirian Stage [32]. 1.1.5. Torlesse Superterrane

The Torlesse Superterrane is voluminous and constitutes more than 60% of the New Zealand landmass. Originally it could have been 200 x 1,000 km in area, and 2-5 km thick. It may be thought of as a vast accretionary complex of Permian to Cretaceous age. It is metamorphosed and varies in grade from prehnite-pumpellyite facies to greenschist facies. It is structurally complex, poorly mapped, and stratigraphic continuity may be difficult to establish for more than a few hundred metres. Torlesse terranes contain a greater variety of sedimentary facies and lithologies than other Triassic terranes in New Zealand. However, they are dominated by clastic sandstone and siltstone lithologies of turbidite aspect, commonly termed 'greywacke', and are mostly composed of redeposited sediments [33, 34]. Oceanic associations of basalt, limestone, chert and hemipelagite are preserved as regionally minor components. These are commonly involved in olistostromal deposits and/or

241 melanges, and are interpreted as tectonically 'scraped' allochthonous entities, originally derived from either oceanic sea floor association or sea mounts, that have become incorporated within the clastic accretionary complex as a result of subduction-related plate margin processes. In a sense, the record of time within the Torlesse Superterrane has been swamped or diluted by sediment. Attempts to determine 'thickness'of Torlesse sequences are at best crude, but it can be stated with some certainty that rates of deposition were high, of the order of 100s to 1,000s of metres per million years and in some cases >2,000 but <10,000 metres per million years. Fossils are generally rare [35, 36]. The Torlesse Superterrane is divided into a number of terranes [34], four of which have a Triassic record: Caples, Rakaia, Pahau and Waipapa terranes. 1.1.6. Caples Terrane The Caples Terrane is poorly understood in terms of both stratigraphy and structure, and is virtually unfossiliferous. All rocks with Triassic faunas (tube fossils and radiolarians) that have previously been considered as Caples Terrane are treated herein as part of Waipapa Terrrane (see below). The Caples Terrane is metamorphosed and varies in grade from prehnite-pumpellyite to lower greenschist facies. It is predominantly composed of redeposited sediment derived largely from a volcanic arc but with a conspicuous quartzofeldspathic component. It contains rare allochthonous blocks of fossiliferous Permian lithologies within conglomerates, olistoliths and melanges, including conodont-bearing Early Permian limestone [37]. Depositional age of Caples Terrane sediments is most probably Early to Middle Triassic. 1.1.7. Rakaia Terrane Fossil content of the Rakaia Terrane indicates a depositional age range of Permian-Triassic. The oldest Triassic fossil is an ammonoid of probable Olenekian age [38]. The youngest Triassic fossils are Rhaetian radiolarians [39]. A number of richly fossiliferous localities are known from clastic successions. Most of these include shelly faunas that are familiar from the Murihiku Terrane, so much so that they are readily recognisable in terms of New Zealand local stages such as the Etalian, Kaihikuan, Oretian, Otamitan and Warepan. Even the Ladinian and Carnian 'gaps' in the fossil record recognised in the Murihiku Terrane appear to also be present in the Rakaia Terrane [3]. Faunas of the Malakovian and Otapirian Stages have not been recognised. The range of fossil content for the Torlesse is the same as for the Murihiku, but for any one locality, there may be differences in faunal composition, diversity and richness. Perhaps the most common fossils within the Rakaia Terrane are tube fossils (e.g. Torlessia) that have been interpreted as agglutinated foraminifera [40]. Plant fossils have been described [40] and demonstrate close affinity with eastern Australian floras. Radiolarian faunas have been recovered from phosphorites within clastic siltstone sequences [39, 42, 43]. They have also been found within allochthonous cherts, as have conodonts [39]. Allochthonous shelly limestones have also produced conodonts. 1.1.8. Pahau Terrane The Pahau Terrane is similar in aspect to the Rakaia Terrane in that it is a long-lived accretionary complex but there is slightly more acid and intermediate volcaniclastic input. Fossils from clastic Pahau Terrane rocks indicate a strictly Jurassic to Cretaceous depositional age range. Triassic fossils are only known from presumed allochthonous ocean floor and sea

242 mount associations. These include radiolarian fossils extracted from chert and siliceous hemipelagite lithologies. Fossiliferous rocks previously treated as Waipapa Terrane in the vicinity of Auckland [44] are now attributed to the Pahau Terrane.

1.1.9. Esk Head Melange The Esk Head Melange is mappable as a major entity separating the Rakaia Terrane from the Pahau Terrane. It has unclear margins but may be thought of as a zone of intense deformation between the two terranes. Compositional studies suggest that much of the matrix is essentially of Pahau origin, but it contains exotic blocks and knockers that are attributed to either a Rakaia origin, or a Pahau ocean floor or sea mount origin. These allochthonous blocks include fossiliferous Triassic limestone, chert and siliceous hemipelagite [39, 45]. Fossils include radiolarians, bryozoans, molluscs and conodonts. 1.1.10. Waipapa Terrane The Waipapa Terrane as used here is restricted to only the 'Bay of Islands Terrane' [46]. However, formerly it has been extended in terms of distribution to include a belt of rocks now mapped as parts of the Caples and Pahau Terranes within both North and South Islands. It ranges in age from Late Permian to Late Triassic. We tentatively include rocks of the Aspiring Terrane [14], as well as the Chrystalls Beach Complex exposed on the Otago coast south of Dunedin, which have produced tube fossils (Titahia) [47] and undescribed radiolarians of Middle Triassic age (Ladinian). These rocks have previously been treated as part of Caples Terrane. Much of the Waipapa Terrane is of oceanic character, dominated by cherts and hemipelagite sequences associated with basaltic rocks. However, it also includes clastic lithologies of Triassic age such as at Kapiti Island [42], which have produced Late Triassic (Norian) radiolarian bearing phosphorites. These are the youngest rocks within the Waipapa Terrane as described herein. An Early Triassic boundary succession is particularly well preserved within coastal exposures at Arrow Rocks, Whangaroa Harbour, Northland [48]. This comprises a sequence of fossiliferous radiolarian and conodont bearing cherts and hemipelagites. On the basis of a black shale interval and organic 813C isotopic signature [48] a Permian-Triassic boundary was thought to be preserved within this sequence but well preserved conodont faunas indicate that this is not the case. Black shales have not been recognised in other New Zealand PermianTriassic terranes. Radiolarians and conodonts indicate a spectrum of Triassic ages including Induan, Olenekian, Anisian, Ladinian, Carnian and Norian. 1.2. Original positions of New Zealand terranes 1.2.1. Paleomagnetism Attempts by workers over many years to elucidate relationships between New Zealand terranes in terms of paleomagnetic studies have all but failed. Results indicate a ubiquitous Cretaceous magnetic overprint within all pre-mid-Cretaceous rocks. The reason for this is a widespread thermal event that affected the entire New Zealand region during mid-Cretaceous time. This 'event' is generally explained in the context of extensional tectonic processes that led to the rifting and separation of the New Zealand microcontinent from Gondwanaland. A few studies have claimed meaningful paleomagnetic results, but the tectonic corrections almost always introduce great uncertainties.

243 1.2.2. Provenance studies Modern research [50, 51, 52, 53] has established the extent to which individual New Zealand terranes are distinct entities in terms of their physical geometry and position in space and through time. They have also been distinguished in terms of original sediment composition, the 87Sr/86Sr isotopic composition at time of metamorphism, and ages of their component detrital minerals. This kind of information has enabled terrane characterisation, particularly for the major suspect sedimentary terranes (Caples, Rakaia, Pahau and Waipapa). Detrital mineral age studies [52, 53] involving U/Pb dating of zircons and Ar/Ar dating of micas (muscovites) preclude a provenance for Caples, Rakaia, Pahau and Waipapa sediments in Antarctica, New Zealand and southeast Australia. Instead, sources in northeastern Australia (Queensland) appear to be most plausible. This is a relatively new and exciting hypothesis, well supported and testable. Interestingly, the oldest detrital zircon ages from Torlesse Superterrane rocks have 3,100 million year ages and are best attributed to a source within the Precambrian core of southeast China [54]. Rubidium-strontium isochron studies on Caples, Rakaia, Pahau and Waipapa Terrane sediments have effectively provided isotopic 'finger print' signatures that are characteristic and distinctive for each terrane. This information greatly constrains the minimum age of the source rocks, the maximum age of their metamorphism, and their general bulk Rb/Sr ratios. For instance, it can be deduced on the basis of 87Sr/Sasr isotopic ratios that the younger Pahau Terrane cannot have been derived from the older Rakaia Terrane. However, the Pahau could have been derived from the Waipapa Terrane or if not, then they have a common source.

1.2.3. Paleobiogeography Attempts to construct paleobiogeographic maps for the New Zealand Triassic are difficult in the absence of any constraint from paleomagnetic data. However, consideration of tectonic theory and biogeographic affinity of known fossil floras and faunas, coupled with lines of constraining evidence such as provenance direction, composition and nature of the sediment substrate/host, and spatial considerations of terranes, provides considerable insight. Sediment of the Caples, Rakaia and Pahau Terranes for instance, is relatively coarse, sand dominated, and must have been deposited rapidly by large energetic rivers that drained a large continental land area of high relief that was almost certainly a response to continent-continent collision processes. It probably accumulated on oceanic crust. Modern submarine depositional processes recognised within large river delta systems may provide insight [55]. A modern analogue might be the Bengal Fan (Ganges River) or the submarine fans developed off the Orinoco and Amazon Rivers. Any map reconstruction showing location of the Caples, Rakaia and Pahau depocentres should place them proximal to a continental landmass. Ongoing paleontological research is seeking to reassess and clarify the paleoenvironmental significance of fossils within terranes. In particular, it is hoped that better resolution of paleolatitude may be possible. Correlation across terranes is also being researched and involves analysis and comparison of fossil biotas of the 'same' age from terrane to terrane. 1.3. New Zealand Triassic Correlations Correlation between terranes within New Zealand is made difficult by the fact that they represent such different environments of marine deposition. Only the Murihiku Terrane

244 accumulated within a shelf environment, whereas the Dun M o u n t a i n - Maitai, Caples, Rakaia and Pahau Terranes accumulated but were not necessarily deposited in bathyal to abyssal depths, and the Waipapa Terrane Triassic represents abyssal sea floor environment. Shelf deposits are present within the Torlesse Superterrane but are all interpreted to be allochthonous. The faunal basis for key biostratigraphic correlations of the New Zealand Triassic is summarised below. 1.3.1. Permian-Triassic boundary Three sedimentary sequences that span a change from Permian to Triassic ages have been recognised in New Zealand. These sequences are within two provinces and three separate terranes as follows: the Parapara Group of the Western Province [ 11 ], and the Dun Mountain - Maitai Terrane [17] and Waipapa Terrane [48, 49] of the Eastern Province. Only the Waipapa Terrane offers any prospect of close biostratigraphic resolution using radiolarians and conodonts. Documentation of these faunas is in progress. 1.3.2. Induan A single ammonoid fauna from Greville Formation, Maitai Group, is recognised within the Dun M o u n t a i n - Maitai Terrane. It includes Durvilleoceras, Episageceras and an undescribed xenodiscid. It is attributed a late Induan (Dienerian) age. Well preserved undescribed Induan conodonts and radiolarians are known from Waipapa Terrane and are currently being documented [48]. 1.3.3. Olenekian Two undescribed ammonoid faunas are recognised from Stephens Formation, Maitai Group [16], within the Dun Mountain - Maitai Terrane. The first comprises species of the families Flemingitidae and Proptychitidae and is attributed an early Olenekian (Smithian) Hedenstroemi Zone age. The second fauna is younger, comprises species of Arctoceratidae, Flemingitidae, Proptychitidae and Procarnitidae, and is attributed an early Olenekian (middle Smithian) Romunderi Zone age. Rare Olenekian conodonts and radiolarians are also recorded from Stephens Formation correlatives elsewhere within the Dun Mountain-Maitai Terrane. Well-preserved undescribed Olenekian conodonts and radiolarians are present in the Waipapa Terrane and are currently being documented [48]. The oldest known Triassic fossils in the Murihiku Terrane are thought to be undescribed flemingitid ammonoids of probable Olenekian age but these are from an isolated out-ofsequence fault sliver. Although it has long been suspected that there is an Olenekian record, fossils of certain Olenekian age have yet to be recognised within the main Murihiku Terrane succession. The oldest Triassic fossil within the Rakaia Terrane is a single ammonoid that is either of latest Olenekian or earliest Anisian age [38]. 1.3.4. Anisian Relatively diverse and relatively rich shelly faunas of Anisian age are preserved within the Murihiku, Dun Mountain- Maitai and Rakaia Terranes. Both the Malakovian and Etalian local stages are attributed to the Anisian on the basis of ammonoid correlations [3]. Neither conodonts nor radiolarians have yet been found in association with these shelly faunas. Previously, the Malakovian Stage was attributed to the Olenekian, but recognition of

245

Ussurites and identification uncertainties of several key taxa within the small ammonoid fauna indicate an early Anisian age. Revisions and new documentation of all Malakovian and Anisian ammonoid faunas are currently underway. How much of Anisian time is represented is unclear, but the Malakovian is best correlated with the Caurus Zone, and the richest Etalian fauna correlates best with Varium Zone. Anisian radiolarians and conodonts are preserved in both Dun M o u n t a i n - Maitai and Waipapa Terranes, and are currently being documented [43, 44]. The only Triassic fossils known from the Western Province (Topfer Formation) are palynomorphs. Some elements are of Early to Middle Triassic age and possibly Anisian [9]. 1.3.5. Ladinian

Restricted but widespread brachiopod dominated shelly faunas of Ladinian age are preserved within the Murihiku, Dun Mountain - Maitai and Rakaia Terranes. In fact, Ladinian brachiopod and molluscan faunas are common to all three terranes. On the basis of halobiid bivalve correlations and scant but distinctive joannitid ammonoid faunas, it is thought that the New Zealand Kaihikuan Stage is restricted to a single ammonoid zone within latest Ladinian time, Sutherlandi Zone [3]. Ladinian conodonts and radiolarians are preserved in Waipapa Terrane (currently being documented) but have not been recognised in any other terrane. 1.3.6. Carnian

Fossils of certain Carnian age are rare in New Zealand and it is conceivable that there are no shelly faunas of Carnian age within the Murihiku Terrane. Previously it has been assumed that the local Oretian Stage is Carnian, but halobiid and scant ammonoid correlations suggest an earliest Norian age [3]. Several undescribed shelly faunas from the Rakaia Terrane may well be of Carnian age on the basis of preliminary halobiid identifications. Carnian radiolarians and conodonts have been recorded from Rakaia Terrane as are radiolarians from Waipapa Terrane [43, 44]. 1.3.7. Norian

Murihiku and Rakaia Terrane faunas of the Oretian, Otamitan and Warepan Stages of New Zealand are all attributed to the Norian, with strong well-established correlations based on halobiid and monotid biostratigraphies, as well as ammonoids, the hydrozoan Heterastridium, and brachiopod lineages (spriferinid, athyrid and rhynchonellid). Norian conodonts have been recorded from both terranes, but are much more common within biogenic lithologies within Rakaia Terrane [3]. Radiolarians of Norian age have been recorded from Murihiku, Rakaia, Pahau and Waipapa Terranes [39, 43, 44]. Western Province (Topfer Formation) palynomorphs include elements of Norian age [9]. 1.3.8. Rhaetian

Murihiku Terrane shelly faunas of the Otapirian Stage are attributed to the Rhaetian. These are dominated by brachiopods [29] but include distinctive latest Triassic arcestid ammonoids and bivalves including the widely distributed Otapiria. Within the Murihiku, Otapirian strata are relatively thick (>1,000 m), post-date Monotis sequences and pre-date fossiliferous

246 Jurassic sequences. Otapirian faunas have not been recognised in any other New Zealand terrane. Rhaetian radiolarians have been recorded from a single locality within Rakaia Terrane [39].

1.3.9. Triassic- Jurassic boundary Fossiliferous sequences that encompass a change from Triassic to Jurassic faunas are preserved within the Murihiku Terrane and probably the Torlesse and Waipapa Terranes. As yet no section has been recognised that enables a precise biostratigraphic determination of the onset of Jurassic time. 1.3.10. Chronostratigraphic potential of New Zealand Triassic successions Both the Dun M o u n t a i n - Maitai and Murihiku Terranes have potential for absolute dating of marker horizons. Both are well endowed with tuffs that are interpreted as primary air-fall volcanic ash beds. The Murihiku Terrane sequences are particularly rich in vitric and crystal tufts with suitable mineral compositions for dating purposes, and some have been dated [56].

2. N E W C A L E D O N I A Fossiliferous marine Triassic strata of the Tdremba Terrane [57] are well exposed along part of the southwest coast of New Caledonia. These sequences are almost identical in every way with those of the Murihiku Terrane of New Zealand. The Kaihikuan, Oretian, Otamitan, Warepan and Otapirian New Zealand local stages are recognised, representative of Ladinian to Rhaetian time in just the same manner as in the Murihiku Terrane [58]. There are subtle differences in terms of diversity and richness of fossil occurrence. The faunas are as for the Murihiku Terrane, but as yet no conodonts or radiolarians have been retrieved from the T6remba Terrane. The oldest Triassic rocks attributed to the T6remba Terrane are those of the Moindou Formation [57]. This unit has a small poorly preserved Early Triassic fauna comprising Ophiceras (Lytophiceras) species and 'Glyptophiceras' attributed to the Induan Commune Zone. An isolated halobiid fossil, Daonella jadii Campbell, is also known. This species was originally described from the Etalian Stage of the New Zealand Murihiku Terrane and is thought to indicate Varium Zone [3]. Rare occurrences of Middle to Late Triassic fossils have been recognised in a second terrane within New Caledonia, the Koh Terrane [57]. Fossils include undescribed Anisian ammonoids, Norian Columbianus and Cordilleranus Zone Monotis faunas, and radiolarians. The Koh Terrane is a diverse magmatic complex with oceanic sea floor associations and volcaniclastic sedimentary enclaves, and is quite different in character from any of the described New Zealand Triassic terranes.

3. A U S T R A L I A Marine strata of Triassic age exist on land in Australia only as small isolated exposures on the western and eastern margins of the continent. They are associated with much more extensive non-marine sequences, and more voluminous submarine deposits in the west, on the

247 Northwest Shelf and in the Perth Basin (Fig. 1) [60]. The latter are known from oil exploration drilling, from the Ocean Drilling Program Leg 122 [61], and from bottom dredgings. Possible locations of the coastline for Anisian and Norian times have been estimated from these deposits and their relations to non-marine strata, and broad marine environments postulated [62]. Early Triassic marine deposits occur both on-land and in the off-shore zone. Well-dated Middle and Late Triassic are known, however, only on the Northwest Shelf. Gondwanaland break-up in the region was under way in the Early Triassic, with a narrow rift valley allowing marine flooding southwards into the Perth Basin between the Indian and Australian part of Gondwanaland. Here along the Northwest Shelf all Triassic stages are probably represented (Fig. 4), although Ladinian and Carnian ages are so far rare. 3.1. Early Triassic The Kockatea Shale of the Perth Basin accumulated during most, if not all, the Early Triassic. Early Induan (early Griesbachian) is indicated by the bivalve Claraia stachei Bittner, middle Induan by Ophiceras (Discophiceras) cf. subkyokticum Spath (late Griesbachian), and Gyronites cf. frequens Waagen, Proptychites, and conodonts (Dienerian), and late Induan (Smithian) by the ammonoids Subinyoites kashmiricus (Diener), Anasibirites kingianus (Waagen) etc. [63, 64]. The Locker Shale in the Carnarvon Basin has conodont faunas indicating late Olenekian (Spathian) age [65]. In Queensland, Gympie Terrane rocks of the Kin Kin Beds have yielded a more diverse ammonoid fauna readily correlated with the Olenekian (early Smithian) Romunderi Zone (species of Latisageceras, Dieneroceras, Anaflemingites, Paranorites, Arctoceras, etc.). The associated Brooweena Beds contain a bivalve fauna dominated by Bakevellia and Neoschizodus regarded as Olenekian (Smithian) by its association with the Kin Kin fauna [60], but comparison with New Zealand faunas of Murihiku and Rakaia Terranes suggests a much younger late Ladinian (local New Zealand Kaihikuan Stage) correlation. Probable marine Triassic is known at one horizon low in the Newport Formation at the top of the Narrabeen Group, Sydney, containing many specimens of a small, undescribed modioline mussel. From stratigraphic position and palynoflora this horizon is believed to be Olenekian (Spathian) in age [66]. 3.2. Middle Triassic An ammonite tentatively identified with the early Anisian Nicomedites is known from the Mt Goodwin Formation in the Bonaparte Basin where it is associated with undetermined halobiid bivalves [64]. The oldest known Triassic dinoflagellate flora in Australia also comes from the Bonaparte Basin and is correlated with the Anisian part of the late Anisian - early Ladinian Sahulidinium ottii dinocyst zone [67]. A rich foraminiferal fauna, Anisian by palynological correlation, has been described from the Northwest Shelf, constituting the oldest known and well preserved such fauna in the region [68]. No certain Ladinian correlation is known, but strata of this age are probably present in the Sahul Group in the Bonaparte Basin and may be represented in the Mungaroo Formation of the Carnarvon Basin.

248 I VVestern Marginal Basins I Eastern Basins I

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Figure 4. Australian sedimentary basins including marine Triassic strata: lithostratigraphic units, fossil groups and conodont and dinocyst zones are presented, as well as age-diagnostic members of other groups (adapted from [59]). E = Epigondolella, H = Heibergella, M Misikella, Mp = Metapolygnathus, N = Neospathodus, R = Rhaetogonyaulax, W -

Wanneria;

Fm = Formation, G p - Group, Sst = Sandstone. 3.3. Late Triassic A conodont fauna from the Bonaparte Basin indicates the Metapolygnathus primitius Zone, which spans the Carnian-Norian boundary. This is the only possibly Carnian marine fauna known in the region, but calcareous nannofloras from the Northwest Shelf are of Carnian age, and transitional Carnian-Norian radiolarian, foraminiferal, and ostracod faunas are also

249 present [61]. A sequence of younger conodonts from exploration wells on the Northwest Shelf indicates the representation of most, if not all, of Norian and Rhaetian time (Fig. 4) [69]. From the same area full Norian-Rhaetian dinocyst and foraminiferal zonations are known [61 ] with apparently unbroken passage into the Jurassic.

4. N E W G U I N E A The Western Highlands of Papua New Guinea include a range of Triassic lithologies of complex structural relationship but with scattered fossils. The Yuat River gorge exposes argillites (Yuat Formation) with a rich molluscan fauna including Paraceratites cf. trinodosus Mojsisovics, Ptychites cf. stachei Mojs., Discoptychites aff. megalodiscus Beyrich, and local species of Beyrichites, Longobardites, and Parapopanoceras [63, 70] of late Anisian Trinodosus Zone. Faunas from sandstones and shales in the nearby Jimi River include halobiid bivalves of Ladinian or Ladino-Carnian age and the ammonoid Sirenites cf. malayicus Welter of CarianNorian age [64] as well as other molluscs and a few brachiopods. In the vicinity of Mt Hagen is found the Kuta Formation, with limestone up to 200 m thick containing a varied molluscan fauna of Rhaetian age including the ammonoid Arcestes cf. sundaicus Welter, the bivalve Rhaetavicula, various brachiopods, corals, and conodonts [71]. The Tipuma Formation of the Bird's Head area of West Irian is a 300-500 m unfossiliferous unit of red argillite and slate with minor sandstone and conglomerate. It lies partly conformably on Carboniferous to Late Permian sediments and is overlain paraconformably by Middle Jurassic to Cretaceous rocks. It is thus dated on stratigraphic grounds as Triassic to Early Jurassic [72].

5. E A S T E R N I N D O N E S I A

In the eastern part of Indonesian archipelago Triassic strata outcrop in Misool, Seram, Buton, Sulawesi, Timor and Rotti islands. 5.1. Misool The sequence in Misool [73] is believed to cover Anisian to Rhaetian time and consists of the Keskain Formation, more than 1,000 m of shale and sandstone, with Beyrichites (Anisian) and Daonella lilintana (Anisian-Ladinian) near the top. The Bogal Formation, dominantly a limestone and c.100 m thick, overlies this unconformably. An early Carnian species of the foraminifer Trocholina occurs low in this unit [74] and near the middle is recorded the Rhaetian Amoenum Zone ammonoids Rhabdoceras suessi Hauer and Cochloceras continuecostatum Hauer. 5.2. Seram

Monotis-bearing limestones on Seram have been confirmed as containing the late Norian M. (Pacimonotis) subcircularis Gabb [75] despite previous argument [76] that the deposits were part of a Late Jurassic flysch sequence.

250 5.3. Buru The Fogi Beds, bituminous limestones and shales with calcareous sandstones, of uncertain thickness, contain a rich molluscan fauna of Norian age and the athyridid brachiopod Misolia that may be confined to the Rhaetian [76, 77]. 5.4. Sulawesi, Buton The eastern and southeastern arms of Sulawesi are reported as including Triassic strata (marly limestones with Cassianella and Hoernesia; sandstones and limestones with Misolia etc.) containing uncommon and poorly preserved fossils [76] which generally do not permit precise stage or zonal correlations, although as noted above Misolia seems to be confined to the Rhaetian. Buton Island, off the southeastern point of Sulawesi, has also yielded a poorly-preserved molluscan fauna from the Winto Beds [76], which are intensely folded and faulted calcareous shales, micaceous and arkosic sandstones, and platy bituminous limestones of unknown thickness. Monotis (Pacimonotis) subcircularis Gabb is characteristic of the late Norian Cordilleranus Zone and provides the only well constrained correlation for the Winto Beds. 5.5. Timor, Rotti The island of Timor is structurally very complex, and this has hindered the unravelling of its geological history. Rich Triassic faunas have been collected but there has been considerable confusion between autochthonous faunas and those from blocks in a huge Miocene slide unit (Bobonaro Scaly Clay) [76, 78]. Nevertheless, most of the Triassic appears to be represented by definitive molluscan faunas associated with conodonts, radiolarians, brachiopods, corals, bryozoans etc. Hallstatt-type limestones contain late Norian Cordilleranum Zone Monotis (Pacimonotis) subcircularis Gabb; halobiid bivalves in pink or grey argillites are widespread, although not common or well-preserved, and indicate early and late Carnian and early Norian, and grey argillites contain Daonella species of early Ladinian to early Carnian ages [76, 79]. In eastern Timor the autochthonous Aitutu Formation [78] reaches 1,000 m in thickness and includes the above faunas together with a rich Carnian cephalopod fauna with Placites meridianus (Welter), Parathisbites scaphitiformis (Hauer), Arcestes malayicus Welter, Proarcestes hanieli Welter, Paratropites cf. sellai (Mojsisovics) and Clydonautilus biangularis Mojs., in a basal conglomerate near Tutuala, where the Ladinian part of the Aitutu Formation is absent. Halobiid faunas indicate that the bulk of this formation is CarnianNorian in age [78]. Triassic strata continue to Rotti Island, off the southwest coast of Timor, where the Norian Monotis (Pacimonotis) subcircularis Gabb has been identified [80].

6. SUMMARY The marine Triassic successions of Australasia include sequences in New Zealand, New Caledonia, Australia, Papua New Guinea and eastern Indonesia. These sequences are generally fragmentary in that individually they represent only portions of Triassic time. Faunal diversity and richness vary considerably as functions of lithofacies, preservation and extent of exposure. However, it can be said that all sequences as presently preserved relate to

251

the break-up of eastern Gondwanaland, demise of the Tethys, the history of the oceanic margins both of the continental Australian Plate and of adjacent oceanic plates. It is presumed that the marine Triassic sequences of Australasia collectively span a broad spectrum of paleolatitude, but this is by no means proven as most are significantly deformed and there is little or no prospect of paleomagnetic control. Only paleontology, isotope chemistry and paleotectonic studies can assist in reconstructing Triassic events and paleobiogeography in Australasia. There is strong evidence to suggest that the New Zealand terranes, as well as those of New Guinea, New Caledonia and eastern Australia, have been systematically transported from a generalised north to south direction around the Gondwanaland margin through time, having originated in lower latitudes than at present found. These ideas require testing. In terms of correlation, tremendous strides forward have been made during the last 25 years with detailed brachiopod, molluscan, conodont, radiolarian and palynomorph biostratigraphy. Although much of Triassic time appears to be represented within Australasia, it is interesting to note significant biostratigraphic gaps in the record for Ladinian and Carnian time. Much new research is under way particularly by Japanese and New Zealand paleontologists in New Zealand where new faunas have been found and new interpretation has recognised significant marine sequences of Early Triassic age. Several Permian-Triassic boundary sequences have also recently been recognised. New Early and Middle Triassic ammonoid, conodont and radiolarian faunas are being described.

7.

ACKNOWLEDGMENTS

The authors gratefully acknowledge the constructive comments of J. D. Campbell, C. J. Adams and N. Mortimer, and thank S. Owen for access to unpublished information on Early Triassic ammonoids of the Dun M o u n t a i n - Maitai Terrane. We also acknowledge access to unpublished information on radiolarian faunas of New Zealand terranes that is currently being documented by Y. Aita, A. Takemura and R. Hori, and access to the unpublished conodont studies of S. Yamakita. We also thank F. Hasibuan for access to unpublished information on the marine Triassic successions of eastern Indonesia. For drafting assistance we thank Louise Cotterall, Michelle Park and Michelle Burgess.

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47. J. K. Campbell, J. D. Campbell, Triassic tube fossils from Tuapeka rocks, Akatore, south Otago. New Zealand journal of geology and geophysics 13(1970): 392-397. 48. A. Takemura, Y. Aita, R. S. Hori, Y. Higuchi, K. B. Sp6rli, H. J. Campbell, K. Kodama, T. Sakai, Preliminary report on the lithostratigraphy of the Arrow Rocks, and geologic age of the northern part of the Waipapa Terrane, New Zealand. News of Osaka Micropaleontologists Special Volume 11 (1998): 47-57. 49. K. M. Rogers, Y. Higuchi, R. Hori, A. Takemura, Y. Aita, T. Sakai, K. Kodama, K. B. Sp6rli, H. J. Campbell, in press: Permian-Triassic Boundary Sequence, Waipapa Terrane, New Zealand: chemical and isotopic evidence. New Zealand journal of geology and geophysics. 50. C. D. Frost, D. S. Coombs, Nd Isotope character of New Zealand sediments: implications for terrane concepts and crustal evolution. American journal of science 289 (1989): 744-770. 51. C. J. Adams, S. Kelley, Provenance of Permian-Triassic and Ordovician metagraywacke terranes in New Zealand: evidence from 4~ dating of detrital micas. Geological Society of America bulletin 110 (1998): 422-432. 52. C. J. Adams, H. J. Campbell, I. J. Graham, N. Mortimer, Torlesse, Waipapa and Caples suspect terranes of New Zealand: integrated studies of their geological history in relation to neighbouring terranes. Episodes 21 (1998): 235-240. 53. C. J. Adams, M. E. Barley, I. R. Fletcher, A. L. Pickard, Evidence from U-Pb zircon and 4~ muscovite detrital mineral ages in metasandstones for movement of the Torlesse suspect terrane around the eastern margin of Gondwanaland. Terra Nova 10 (1998): 183-189. 54. C. J. Adams, A provenance in northeast Australia and South China for New Zealand Paleozoic terrane sediments. Journal of African earth sciences 27 (1998): 218-219. 55. M. Maslin, N. Mikkelsen, C. Vilela, B. Haq, Sea-level- and gas-hydrate-controlled catastrophic sediment failures of the Amazon Fan. Geology 26 (1998): 1107-1110. 56. G. J. Retallack, P. R. Renne, D. L. Kimbrough, New radiometric ages for Triassic floras of southeast Gondwana. In: S. G. Lucas and M. Morales (eds) The Non-marine Triassic. New Mexico Museum of Natural History and Science bulletin 3 (1993): 415-417. 57. J. C. Aitchison, T. R. Ireland, G. L. Clarke, D. Cluzel, A. M. Davis, S. Meffre, Regional implications of U/Pb SHRIMP age constraints on the tectonic evolution of New Caledonia. Tectonophysics 299 (1998): 333-343. 58. H. J. Campbell, J. A. Grant-Mackie, Biostratigraphy of the Mesozoic Baie de St. Vincent Group, New Caledonia. Journal of the Royal Society of New Zealand 14 (1984): 349-366. 59. H. J. Campbell, Y. Bando, Lower Triassic ammonoids of New Caledonia. G6ologie de la France 1 (1985): 5-14. 60. B. E. Balme, C. B. Foster, Triassic (Chart 7). In: G. C. Young, J. R. Laurie (ed.), An Australian Phanerozoic timescale, Oxford University Press, Melbourne (1996): 136-147. 61. W. Brenner, P. R. Bown, T. J. Bralower, S. Crasquin-Soleau, F. Depeche, T. Dumont, R. Martini, W. G. Siesser, L. Zaninetti, Correlation of Carnian to Rhaetian palynological, foraminiferal, calcareous nannofossil and ostracode biostratigraphy, Wombat Plateau. Proceedings of the Ocean Drilling Program, Scientific Results 122 (1992): 487-495. 62. J. Dercourt, E. Ricou, B. Vrielynck (eds.), Atlas Tethys palaeoenvironmental maps, Gautier-Villars, Paris (1993). 63. R. A. McTavish, J. M. Dickins, The age of the Kockatea Shale (Lower Triassic), Perth Basin - a reassessment. Journal of the Geological Society of Australia 21 (1974): 95-201. 64. S. K. Skwarko, B. Kummel, Marine Triassic molluscs of Australia and Papua New Guinea. Bureau of Mineral Resources bulletin 150 (1974): 111-127. 65. R. A. McTavish, Triassic conodont faunas from Western Australia. Neues Jahrbuch for Geologie und Pal~iontologie, Abhandlung 143 (1973): 275-303. 66. J. A. Grant-Mackie, D. F. Branagan, H. R. Grenfell, A new mussel (Mytilidae, Bivalvia) from the Sydney Basin Triassic. New Zealand Geological Survey record 9 (1985): 53-55. 67. L. E. Stover, R. J. Helby, Some Australian Mesozoic microplankton index species. Association of Australasian Palaeontologists memoir 4 (1987): 101-134. 68. R. S. Heath, M. C. Apthorpe, Middle and Early (?) Triassic foraminifera from the Northwest Shelf, Western Australia. Journal of foraminiferal research 16 (1986): 313-333.

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69. P. J. Jones, R. S. Nicoll, Late Triassic conodonts from the Sahul Shoals No.l, Ashmore Block, northwestern Australia. Bureau of Mineral Resources journal of Australian geology and geophysics 9 (1985): 361-364. 70. S. K. Skwarko, Middle and Upper Triassic Mollusca from Yuat River, eastern New Guinea. Bureau of Mineral Resources of Australia bulletin 126 (1973): 27-50. 71. S. K. Skwarko, R. S. Nicoll, K. S. W. Campbell, The Late Triassic molluscs, conodonts, and brachiopods of the Kuta Formation, Papua New Guinea. BMR journal of Australian geology and geophysics 1 (1976): 219-230. 72. P. E. Pieters, C. J. Pigram, D. S. Trail, D. B. Dow, N. Ratman, R. Sukamto, The stratigraphy of western Irian Jaya. Geological Research & Development Centre bulletin 8 (1983): 14-48. 73. F. Hasibuan, Mesozoic stratigraphy and paleontology of Misool Archipelago, Indonesia. Unpublished PhD thesis, Univ.of Auckland Library (1990). 74. E. Kristan-Tollmann, personal communication to J.A.G-M (1989). 75. G. E. G. Westermann, Species distribution of the world-wide Triassic pelecypod Monotis Bronn. Proceedings of the 22nd International Geological Congress, India, 1964, Section 8 (1973): 374-389. 76. R. W. van Bemmelen, The geology of Indonesia, Vol.lA.Government Printing Office, The Hague (1949): 732p. 77. F. Hasibuan, J. A. Grant-Mackie, in prep. Contribution to the Mesozoic paleontology of the Misool archipelago, eastern Indonesia. 78. M. G. Audley-Charles, The geology of Portuguese Timor. Geological Society of London, London (1968): 75p. 79. Identifications made by us in collections made by Dr S.T. Barkham, Royal Holloway & Bedford New College, University of London, in the early 1980s in the Nefokoko area of west Timor. 80. K. Ichikawa, Zur Taxonomie und Phylogenie der triadischen "Pteriidae" (Lamellibranch.) mit besonderer Beruchsichtigung der Gattungen Claraia, Eumorphotis, Oxytoma und Monotis Palaeontographica A111 (1958): 131-212.

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Persian-TriassicEvolutionof Tethys and WesternCircum-Pacific H. Yin, J.M. Dickins,G.R. Shi and J. Tong (Editors) o 2000 ElsevierScienceB.V. All rightsreserved.

The northern margin of Gondwanaland: lowermost Jurassic and its correlation

257

uppermost Carboniferous to

J.M. DICKINS Innovative Geology, 14 Bent St, Turner, A.C.T. 2612, Australia

In the latest Carboniferous and the early Early Permian no continuous sea is apparent in the position of Tethys s e n s u Suess. In the earliest Permian, there was a land barrier separating Central Asian Sea from the southern sea connecting "Gondwana" countries The youngest recognized marine deposits connecting through the warm water Central Asian Sea are not younger than Early Permian (Sakmarian). In the Upper Permian and Triassic a northern shore of Gondwanaland can be traced with a southern sediment source. The northern shore of Tethys largely remains to be delineated. Thus, whether the terms Tethys and Gondwanaland have valid usage before the mid-Permian is an important question.

1. I N T R O D U C T I O N Although the term Gondwana was first used for a sequence largely of terrestrial rocks of Peninsular India ranging in age from the lower part of the Permian to the mid-Cretaceous and applied as a stratigraphical interval (e.g. Gondwana Sequence, Series or System) to their equivalents in the southern continents (Africa, Australia, South America and Antarctica) [ 1-3 ], Gondwana and Gondwanan have often been used in such a broad and unclear manner that the term has become quite confusing. On the other hand Suess coined the word Gondwana-land (here used as Gondwanaland) with quite a different meaning for the land which he considered from his understanding of marine Jurassic rocks to exist south of the sea which he called Tethys. The land, which he considered to exist north of Tethys, he called Angara-land. Suess's Tethys connected eastern Asia through southern Asia across the Himalayas and Tibet with the Middle East and Europe. Here it is proposed to use these terms in their original sense and to examine the northern margin of Gondwanaland from the later part of the Carboniferous to the beginning of the Jurassic and particularly to examine the northern shore of Gondwanaland during this time and the correlations and implications associated with such a study. In this study, the question is raised whether the term Gondwanaland (or its versions Gondwana or Gondwanan), is meaningful before the Permian and especially the midPermian. It is only from the mid-Permian that a sea across southern Asia conforming to Suess's definition of Tethys can be clearly recognized with a clear southern boundary stretching across northern Africa and southern Asia and defining a southern landmass named Gondwanaland.Already by the end of the Jurassic and almost certainly by the mid-Cretaceous, this southern boundary has gone with the first indications of the Indian Ocean as we now see it appearing in the Jurassic. A consideration of this question is outside the scope of this paper but has been discussed by Dickins [2,3].

258 In South America during the Carboniferous to Jurassic there is no indication of any sea, as, for example, in southern Asia, which would divide off an area which could be called Gondwanaland and there is no clear boundary of Gondwanaland. Only during the Carboniferous and Permian and then intermittently is there a fauna and flora that could be described as a Gondwana or Gondwanaland fauna and flora. With perhaps only one or two exceptions, in all of the marine faunas, direct links with North America and the northern continents are apparent. At times the faunas are entirely northern in character. In this paper it is not proposed to deal further with the South American relationships.

2. U P P E R C A R B O N I F E R O U S

The continentality of the upper and particularly the uppermost part of the Carboniferous is an outstanding world feature and although well known in anectdotal geology, has been poorly recognized in recent literature. The hiatus found in many parts of the world has been recognized in the terms "Hercynian Gap", "Hercynian Unconformity" or even the "Great Hercynian Unconformity" as used recently by Alsharhan and Nairn [4]. The poor representation of marine deposits which are found mainly in the present equatorial regions has been recognized, for example, by Rausser-Chernousova et al. [5]. An exception to the equatorial occurrence of marine deposits seems to be in the Canadian Arctic [6-8]. Although much detailed work remains to be done, even here, widespread hiatus and unconformity is found at the Carboniferous-Permian boundary (see especially [8], Figure 3). In the development of the Hercynian (Variscan) Orogenic Phase, I have noted the continentality associated with the end of this phase at the end of the Carboniferous and that the Lower Permian represents a world wide tensional phase lacking compressive folding [inter alia 9-12]. The nature of this continentality and the end of the Hercynian Orogenic Phase is particularly illustrated in Figs. 15.2-4 of Dickins [10]. In India and in the present southern hemisphere, the beginning of the Permian is also associated with widespread glaciation [13, 14]. In Australia the continentality of the Upper Carboniferous has been associated with a conjectural continental glaciation in the Upper Carboniferous by Powell and Veevers [15]. This is discussed by Dickins [14] and its consideration is outside the scope of the present paper. In this context, uppermost Carboniferous deposits are generally absent from northern Africa through the Middle East, Turkey and the Arabian Peninsula, to Iraq, Iran, Peninsular and Himalayan India across southern Thailand to western Australia. Where there are indications of presence, the deposits are terrestrial or marginal marine. Kulke [16] records that across northern Africa, uppermost Carboniferous is missing, continental or marginal marine. Selley [ 17] records no uppermost Carboniferous from northern Africa accept possibly some marginal marine in northeast Egypt and from Jordan, Turkey, the Arabian Peninsula, Iraq and Iran a lack of Upper Carboniferous is reported [18-20]. Marine Permo-Carboniferous successions are recorded in the Gulf of Suez, Egypt [21] but what part of the Carboniferous and the Permian is represented is not clear to me from the descriptions of the faunas. The corals from part of this sequence [22] suggest Westphalian or Stephanian for this part of the sequence. The authors consider the sequence represents marginal marine conditions which is supported by the nature of the faunal associations. As shown later in this paper, in the western part of the Arabian Peninsula, the Upper Permian overlaps older formations onto the Precambrian and in northern Oman, the Upper Permian rests on Infracambrian and

259

Ordovician [23]. In Central Arabia, the Hercynian Gap referred to as the Hercynian Uplift extending from Upper Devonian to Lower Permian is shown very clearly by McGillivray [24, Figure 2]. Figure 2 is based on his own work and that of a number of earlier publications. It may be noted that in the southern Arabian Peninsula, the lowermost Permian is often ascribed to the Upper Carboniferous, although the palynological data from these non-marine rocks indicates they are Lower Permian [11]. In Iran, Stocklin [20] says " A more important regional disconformity is observed at the base of the Permian, which throughout Iran marks a marine transgression after a period of emergence in late Carboniferous time". In Peninsular India as I have observed myself in a number of places, glacial and marine Lower Permian overly Precambrian where they constitute the base of the Gondwana sequence. In Himalayan India the uppermost Carboniferous is unknown and is represented by a hiatus in recorded sequences. In Kashmir gaps appear to be present between the "Fenestella Shale" and on in the Agglomeratic Slate where the oldest fossils of Permian age appear with the incoming of basaltic detritus (work in preparation). Waterhouse and Gupta [25, 26] regarded the marine fauna of the "Fenestella Shale" as of Lower Carboniferous (Visean to Namurian). More recent work [27, 28] suggests that the "Fenestella Shale" in Spiti, South Tibet, Nepal and India may be younger and of lower upper Carboniferous (Bashkirian) age with overlying marine beds of Moscovian age. In Nepal a southern source for the sediments has been recorded [29]. I have not so far been able to find any record of true uppermost Carboniferous marine beds in Tibet. It seems that southwestern and south central Asia as far north as the Tarim Block to the Central Asian Sea were extensively or entirely a land area in the uppermost Carboniferous and, as indicated in a later section, there was almost certainly no marine east-west sea connection through southern Asia, when the connection through Sinkiang and the Central Asian remained. This sea connection, however was broken by the mid-Permian and since that time up to the present, there has been no connection through this region from eastern Asia to western Asia and Europe. The youngest marine deposits are Asselian or Sakmarian [see 5, 30 - Kunlun-Qaidam and Tianshan-Hingan regions, p.110 under Carboniferous System, 31, p.237). Whether there are any uppermost Carboniferous marine deposits in Thailand and Indochina is not clear [e.g. see 32-34]. In Peninsular Thailand, marine Lower Carboniferous is overlain by a thick flysch sequence with turbidity current, mud and debris flow deposits considerably folded and with much slumping [35-39]. Here the term flysch is used in a strict sense for "the later stages of filling of a geosynclinal system, by rapid erosion of an adjacent and rising mountain belt" [40]. Such sequences have characteristic features and although the term has been used in a loosely applied way to almost any turbidite [40], it is not used in that way here. Where I have examined these sediments, they contain large quantities of intermediate to acidic volcanic detritus. Such deposits make up, in part or in whole, the pebbly mudstones of southern and southeast Asia. It is apparently these deposits sometimes described as diamictites to which a glacial origin has been ascribed, e.g. [41,42]. Neither my field examination, nor the earlier examination of Garson et al. [36] or Altermann [37, 38] has shown any criteria which would indicate they were glacial. Although Garson et al. [36] record Upper Devonian-Lower Carboniferous marine fossils, no fossils has been have been discovered clearly from this flysch sequence which would indicate age. In appearance they seem to be similar to the "Fenestella Shale" which I have examined in Kashmir and may well correspond to the "diamictites" of a general Middle Carboniferous age described from South Tibet, Nepal and Himalayan India [43]. Suensilpong et al. [44] and Altermann [37] have suggested that this flysch sequence represents part of a Carboniferous orogeny which is well

260

developed in Peninsular Thailand and in adjacent parts of Burma and Malaysia and Sumatra, with the absence of Upper Carboniferous over much of the region. This seems confirmed by the presence of Carboniferous granite in the Himalayas (290-360 m.y.[45] and Kapoor, Maheshwari and, Bajpai [46] have also identified Hercynian Orogeny in the Carboniferous of the Himalayas. Altermann [37, 47, Fig.9] postulates a west verging subduction zone from Devonian to Triassic at about the present western margin of Thailand. There seems little doubt, although details such as exact timing and geographical extent remain to be investigated, that during the Carboniferous, an orogenic fold belt extended across southern Asia through the Himalayan region into Southeast Asia through Burma, Peninsular Thailand and Malaya, with which was associated extensive volcanic activity supplying detritus from a western hinterland eastward into the extensive "pebbly mudstone" belt of Burma, Peninsular Thailand and Malaya. In the Permian and Triassic a geosyncline appears to have developed with the compression directed to the west beginning in the Upper Permian and associated with the Bentong-Raub and Petchabun "Lineament" in Malaysia and Central Thailand [47-49]. The flysch sequence in Peninsular Thailand is separated from the Upper Permian Rat Buri Limestone by several hundred metre of siltstone, mudstone and sandstone, pebbly in places and with tuff and volcanic detritus which is considerably less indurated than the underlying sequence and has a diverse marine fauna. Garson et al. [35] placed the base of this unit at a distinctive Fenestella band and separated it on the basis of its different sedimentary character. Waterhouse, Pitakpaivan and Mantajit [50] considered the age to be Sakmarian to Artinskian but favoured Sakmarian. Its fauna, however, although clearly Permian, differs considerably from faunas of Sakmarian age from western Australia and southern Asia. It is unlikely to be older than Sakmarian but may be younger [51 ]. In the uppermost Carboniferous it appears that the Central Asian Sea was bounded on the south by a large land area extending from Africa across the Middle East and southern Asia to Australia. The connection of eastern Asia with the Middle East and Europe was through the Central Asian Sea and no branches of the Central Asian Sea to the south are known. The Central Asian Sea apparently was in existence already at the beginning of the Phanerozoic and existed until the Lower Permian. Whether any persistent southern Asian sea existed at this time before uppermost Carboniferous remains doubtful. Dickins [3] could find no evidence of such a sea in the Upper Devonian or the Lower Carboniferous. In the Permian no Tethys in the sense of Suess is apparent until the Upper Permian and whether in the uppermost Carboniferous, this land south of the central Asian Sea should be called Gondwanaland is questionable as, indeed is its use prior also to the uppermost Carboniferous [3, 51]. Use of the term Gondwana in this context has already been questioned earlier by Kapoor and Gopal Singh [52].

3. L O W E R PERMIAN

Here a twofold major subdivision of the Permian into Lower and Upper Permian is used corresponding to the traditional usage in the Permian type area and in many other parts of the world. As mentioned earlier the youngest marine deposits in the Central Asian Sea are lowermost Permian. At this time (Asselian and Tastubian - lower Sakmarian) a land barrier apparently existed between Southeast Asia, India and southern Tibet on one hand and China and central

261 Asia on the other hand which were connected with the Middle East and Europe through the Central Asian Sea [51]. This was the time of the glaciation and all the southern faunas of Asselian and Tastubian age show the imprint of these climatic conditions [11,14]. During the Sterlitamakian there is a marked amelioration in climate, although a distinctive difference between the "Gondwana" faunas and more northerly faunas remains. Whether this reflects the continued presence of land barriers, deep ocean or a difference in water temperature or some other factor is not clear. From my examination, the Sterlitamakian (upper Sakmarian) "Gondwana" fauna of Oman, however, shows some warm water elements in its fauna [53, 54] and the equivalent "Gondwana" Boashan fauna of western China contains fusulinids giving a definite indication of warm water [55 - fide 56, 57]. Fang [58] has already argued that no authenticated glacial deposits or cold-water fauna are present in the Baoshan Block nor in the Sibumasu Province and this seems to be the only conclusion that can be drawn from the available information. However this may be, these faunal differences were swept aside by the changes at the mid-Permian when a Tethys in the sense of Suess was clearly established across southern Asia through the Middle East to southern Europe and northern Africa with a southern shoreline marking the northern boundary of Gondwanaland and a cosmopolitan warm water fauna. Leven [32] describes an event associated with the Sakmarian-Artinskian boundary marked by widespread hiatus and structural change in "Tethys". This event may coincide with the end of the Central Asian Sea and clearly has a world wide character. From Baghbani's chart [59], it is widespread in Iran. It is recognizable by hiatus, unconformity and structural change in western and eastern Australia [60] and in the USA [61]. From Leven's tabulation and Baghbani's chart, after the Sakmarian, Lower Permian marine deposits are sparsely developed in southern Asia through the Middle East to Iran, Afghanistan and India. There is no indication of a marine connection across southern Asia before the major transgression marking the mid-Permian, which could be validly called Tethys in the sense of Suess. A connection may have been present, albeit intermittently, through the Central Asian Sea which was removed by the tectonic and erosional events of the mid-Permian or there may not have been a direct connection between eastern Asia and the Middle East and Europe. No Lower Permian faunas have been authenticated from northern Africa. In Asia (extensively considered in Dickins [11, 52] - see also {62, 63]), the Asselian-Tastubian "Eurydesma fauna" is known from Peninsular India, the central and northern Himalayas, the Pamirs, the Salt Range (Pakistan) and northwest Tibet. The Sterlitakmakian fauna is known from Oman, Peninsular India, the Himalayas, the Pamirs, Tibet and western China. It may possibly be more widespread as for example in Afghanistan and Timor. The report in western Thailand is doubtful. In the eastern Himalayas, western China and western Thailand if present, the Sterlitamakian rests on pre-Permian beds. No clear sea connection except with Australia is apparent on the present available information. The marine Artinskian and apparently also the Kungurian are absent or sparsely recognized in southern Asia and the sea connections are not clear except in Thailand and southeast Asia where the faunas seem to be related to China and the north. If New Guinea [64] and Timor [65] and my personal examination are taken into account, there is some suggestion from the faunas that there is a gradual change from Australia northwards towards China. Kapoor and Maheshwari [66] and Kapoor, Maheshwari and Bajpai [46] have concluded that in the Lower Permian in the Himalayan region, there was a sea which they named Kshir Sagar separate from a sea to the north which they regarded as Tethys. The Kshir Sagar was

262 connected with Gondwanaland. In the mid-Permian the transgression of Tethys [67] marked the beginning of the Indosinian (Hunter-Bowen (Indosinian) of this paper) Orogeny.

4. U P P E R P E R M I A N

At the mid-Permian the northern boundary of Gondwanaland is clearly indicated by the southern boundary of Tethys from northern Africa through southern Arabia and across Iran to northern Peninsular India and south parallel to Peninsular Thailand and Malaysia (see accompanying figure). This sea is outlined by the deposits of Kubergandian, Murgabian and Midian age. The mid-Permian, which apparently represents the widest spread of Tethys in the Permian, is extensively tabulated [ 12, 51 ].

Figure 1. Northern shoreline of Gondwanaland at the mid-Permian (boundary of Lower and Upper Permian twofold Permian subdivision: beginning of "Upper" Ufimian = Kubergandian = Roadian). The data considered in the text would give a strong indication that this is the most extensive southern transgression of Tethys onto Gondwanaland during the Permian and Triassic The only marine Upper Permian known from northern Africa is found in Tunisia [68]. A clear shoreline has been identified from the distribution of the Khuff Formation and its marginal deposits in the Arabian Peninsula running easterly of the Red Sea in a southerly direction and turning more or less parallel to the southern margin of the Peninsula through Oman to eastern Oman [12, 18, 4]. Broutin et al. [69] in discussing the non-marine Permian of

263 central Morocco compare their Early-Late Permian transition flora with that of the Gharif Formation of the Arabian Peninsula and show a southern boundary of Tethys as tabulated here. The Gharif Formation immediately underlies the Khuff and apparently represents the marginal phase of the mid-Permian marine transgression of the Khuff. In the Oman Mountains of eastern Oman, although the Upper Permian is structurally complicated, a southern source of sediments can be shown [70, 23]. The shoreline across Iran remains to be tabulated but runs across India, north of Peninsular but south of Himalayan India with transgression from the north [71, 66]. Kapoor and Tokuoka [66] record shelf sediments in the Higher Himalayas and Kashmir and a supply clastic materials from Gondwanaland in the south. The shoreline then runs south close and parallel to the Thai-Malayan Peninsula. The Upper Permian Ratburi limestone is a platform carbonate developed west of the contemporaneous north-south Phetchabun Fold belt of central Thailand and as it approaches the Thai Peninsula, brachiopd faunas become common and the fusulinids are poorly represented suggesting an approach to land with shallower, more turbid water [51 ]. The internal character of Tethys in the Permian and Triassic is outside the scope of this paper. Volcanic activity is widespread and deep as well as shallow water sediments and flysch-like deposits. Although many papers have appeared describing terrane movement within Tethys, very little synthesis of detailed factual information has been undertaken which might allow a realistic comparison with what are apparently the present existing structural, volcanic and sedimentary analogues. The internal structure appears to have been quite complicated and various very inconsistent and contradictory tectonic explanations have been tabulated [72]. It might be informative to relate the deeper water sediments of Sicily and Oman [23, especially Fig. 7, 73, 74, 75] to see if adjacent volcanics represent a "back-arc" (volcanic central graben) relationship. From Stocklin's [20] account of the Triassic of Iran, the Oman deep-water sediments could well represent the trench (fore-arc) related to the Zagros Thrust Zone. In Vietnam, the Songda Trough or Depression with strong volcanic activity in the Permian and Triassic [76] might well represent the volcanic back arc graben associated with the flysch deposits pointing to a trench to the north. Because of the similar type of deposits and faunas on either side of the depression during the Carboniferous, Permian and Triassic, it could hardly have been a suture at this or subsequent time. Similar geosynclinal deposits and igneous activity are found in Tibet, central Thailand, Malaysia and northwest and western China [see for example 77, 48, 49, 78, 30, 79, 80, 47, 81, 82, 83] and how they might be related to each other remains to be satisfactorily investigated. A major regression-transgression is associated with the Midian-Dzhulfian boundary after which the sea is was progressively restricted with possibly complete regression associated with the Permian-Triassic boundary. This has been discussed by Dickins, Yang and Yin [84] and it is not practicable to discuss it further here. The Midian-Dzhulfian boundary is the base of the Lopingian comprising two stages most commonly termed the Dzhulfian and the Chanhgsingian. Despite this regression, however, there is a change in the geographic distribution of marine deposits and, for example, apparently Lopingian with, according to the bivalves, possibly earlier Permian is found in Madagascar [85], the only marine Permian known there. In western Australia, marine Dzhulfian is present in areas where older Upper Permian marine deposits have not been identified [60]. In Tethys, however, Dzhulfian is generally located to the north of the southern boundary as located in the lower part of the Upper Permian.

264 5. TRIASSIC In the Lower and Middle Triassic, the southern shoreline of Tethys and the northern margin of Gondwanaland appears to have approximated to that of the mid-Permian (Figure 1) in the context of a series of transgressions and regressions with the transgressions coming from the north onto a general southern land. Nowhere, however, from northern Africa to the southern Arabian Peninsular, Iran and India is the sea known to penetrate further to the south onto Gondwanaland than in the mid-Permian. Indeed this study seems to confirm that the most far flung marine trangression in all Permian and Triassic time was at the mid-Permian (twofold subdivision of the Permian), corresponding to the beginning of the Hunter-Bowen (Indosinian) Orogenic Phase. This was a time of major rearrangement of sedimentary basins and important faunal and floral changes [12]. Non-marine and marginal deposits are identified across northern Africa and southward, east and parallel to the Red Sea and easterly through Oman [86, 19, 4]. Land also existed to the south of Himalayan India and clastic sediments coming from the south are recorded [66, 87]. Garzanti, Nicora and Rettori [28] show "Gondwana" (Gondwanaland) south of Himalayan India. Shallow water Triassic is present in Peninsular Thailand deepening towards the east [88, 89]. There is no indication of sea connections to the south or west respectively of India or Burma,Thailand or Malaysia. A lack of southern and western sea connections seems also suggested for the Lower, Middle and Upper Triassic by the detailed information for eastern and south-eastern Asia as far west as the Himalayas presented by Yin [90], which could hardly be bettered and no attempt is made to repeat it here. The connection with western Australia was apparently through the East Indies.Yin also shows a northern margin of Tethys throughout the Triassic in the Tibetan region. A major change occurs in the Upper Triassic with the strong development of folding of the Hunter-Bowen (Indosinian) Orogenic Phase [20, 91, 34, 30]. In eastern Vietnam and southern China uplift formed a land area and an eastern boundary of Tethys which persisted into the Jurassic. Yin [92] shows that during the Upper Triassic the connection of the sea in eastern Asia with the Himalayan Region and central and Western Tethys was apparently through the East Indies and the Thai-Malayan region.

6. JURASSIC In the Middle East and India, the first transgressions from the south are found giving an indication of an Indian Ocean as we see it now. These are found in the southern Arabian Peninsula and in the Kutch Region of India [93, 94, 4]. At the same time a southern source of sediment is still indicated which persists into the Cretaceous. Similarly the Jurassic transgression from the south and east in Vietnam, gives an indication of a Pacific Ocean influence [91, 95].

7. C O N C L U D I N G REMARKS When Suess coined the name Tethys for a Mesozoic sea which stretched across southern Asia to the Middle east and Europe, he called the land to the south Gondwanaland and the land to the north Angaraland.

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In the latest Carboniferous and the early Early Permian no continuous sea is apparent in this position. From Africa to the Himalayas and perhaps further to the east, a vast land area stretched to the Central Asian Sea, north of Tarim. In the earliest Permian, there was apparently a land barrier north and east separating the Himalayas and Tibet from the Central Asian Sea. The southern sea which connected with other southern "Gondwana" countries at this time which was a widespread time of glaciation in these countries, was called the Kshir Sagar by Kapoor and Maheshwari and Kapoor, Maheshwari and Bajpai [61, 45]. The youngest recognized marine deposits connecting through the Central Asian Sea, and which have a warm water character, are not younger than Early Permian (Sakmarian). There is no later east-west marine connection through Central Asia up to the present. Connections (if any) of the Kshir Sagar to the north in later part of the Lower Permian are obscure until the mid-Permian (twofold subdivision of the Permian based on the Russian type area) when the Tethys of Suess is clearly established by the major tectonic and palaeogeographical changes of the mid-Permian [ 12, 51, 45]. Whether the terms Tethys and Gondwanaland have any valid usage before the midPermian is an important question. In the Upper Permian a northern shore of Gondwanaland can be traced with a southern sediment source, from northern Africa through the southern Arabian Peninsular, south of the Himalayas and then southerly parallel to Peninsular Thailand. In the Triassic a similar shoreline and sediment direction is found. Some evidence suggests a southern and western shoreline with land west and south of Malaysia, the East Indies and western Australia. The northern shore of Tethys largely remains to be delineated except for north of Tibet and eastern Asia [92] and what land was present and its shoreline within Tethys are not clear except for the suggested archipelago character of Tethys in China as described by Yin [90]. In the Jurassic and Cretaceous, in Africa and the Middle East, a southern source of sediment is maintained but the penetration of marine tongues from the south give an indication of the presence of an Indian Ocean as we see it at present. Similarly in southeastern Asia in the Jurassic, penetration of marine tongues from the east and southeast give an indication of a Pacific presence. In South America there is no clear boundary of Gondwanaland. During the Carboniferous and Permian at least, there are links in the marine faunas and the land plants with other "Gondwana" countries but virtually in all the marine faunas direct links with North America and the northern continents are apparent. At times the faunas are entirely northern in character.

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69 Broutin, J., Aassoumi, H., El Wartiti, M., Freytet, P, Kerp, H., Quesada, C. and Toutin-Morin, N., 1998. The Permian basins of Tiddas, Bou Achouch and Khenifra (central Morocco). Biostratigraphic and palaeophytogeographic implications. In Peri-Tethys Memoir 4: epicratonic basins of Peri-Tethyan platforms. Memoirs Muse6 National d'Histoire Naturelle 179: 257-279. 70. Blendinger, W., 1988. Permian to Jurassic deep water sediments eastern Oman Mountains: their significance for the evolution of the Arabian margin of the south Tethys. Facies 19: 1-32. 71. Dickins, J.M. and Shah, S.C., 1981. Permian paleogeography of Peninsular and Himalayan India and the relationship with the Tethyan Region. In Gondwana Five (M.M.Cresswell and P.Vella Eds.), Balkema, Rotterdam: p.79-83. 72. Dickins, J.M., 1964. What is Pangaea ? In Pangea: Global environments and resources (A.F.Embry, B.Beauchamp and D.J.Glass Eds.). Canadian Society of Petroleum Geologists Memoir 17: 67-80. 73. Catalano, R., Di Stefano, P. and Kozur, H., 1991. Permian Circumpacific deep-water faunas from the western Tethys (Sicily, Italy) - new evidences for the position of the Permian Tethys. Palaeogeography, Palaoclimatology, Palaeooecology 87: 75-108. 74. Catalano, R., Di Stefano, P. and Kozur, H., 1992. New data on Permian and Triassic stratigraphy of western Sicily. Nueus Jahrbuch fur Geologie e Palaontologie Abhandlungen 184:25-61. 75. Flugel, E., Di Stefano, P.Senowbari-Daryan, B., 1991. Microfacies and depositional structure of allochthonous carbonate base-of-slope deposits: the Late Permian Pietra di Salomone Megablock, Sosio Valley (western Sicily). Facies 25: 147-186. 76. Dickins, J.M., 1996. Permian and Triassic events in Vietnam and implications for economic geology. Geological Survey of Vietnam Journal of Geology Series B 7/8: 235-39. 77. Stocklin, J., 1980. Geology of Nepal and its regional frame. Journal of the Geological Society of London 137: 1-34. 78. Jin Yugan, 1985. Permian Brachiopoda and paleogeography of the Qinghai-Xizang (Tibet) Plateau. Palaeontologia Cathayana 2:19-71. 79. Yin Jixiang, Xu Juntao, Liu Chengjie and Li Huan, 1988. The Tibetan plateau: regional stratigraphic context and previous work. Philosophical Transactions of the Royal Society of London A 327: 5-52. 80. Huang Zhixun, 1989. Paleobiogeography and paleostructure of Carboniferous-Permian in north Qinghai-Xizang (Tibet) Plateau. Compte Rendu Onzieme Congres International de Stratigraphie et de Geologie du Carbonifere (Jin Yugan and Li Chun Eds.) 4: 197-208. 81. Dickins, J..M., Shah, S.C., Archbold, N.W., Jin Yugan, Liang Dingyi and Liu Benpei, 1993. Some climatic and tectonic implications of the Permian marine faunas of Peninsular India, Himalayas and Tibet. In Gondwana Eight: Assembly, evolution and dispersal (R.H.Findlay, R.Unrug, M.R.Banks, and J.J.Veevers Eds.): 333-343. A.A.Balkema, Rotterdam. 82. Zhang Boyou, Shi Manquan, Yang Shufen and Chen Hanlin, 1995. New evidence of the Paleotethyan orogenic belt on the Guangdong-Guangxi border region, South China. Geological Review 41: 1-6. 83. Da Yuansheng, Feng Qinglai, Yin Hongfu, Zhang Zongheng and Zeng Xianyou, 1996. New evidence for eastward extension of late Hercynian-early Indosinian Qinling Sea. Journal of China University of Geosciences 7:141-146. 84. Dickins, J.M.,Yang Zunyi and Yin Hongfu, 1997. Major global change: framework for the modern world. In Late Palaeozoic and Early Mesozoic Circum-Pacific events and their global correlation (J.M.Dickins, Yang Zunyi, Yin Hongfu, S.G.Lucas and S.K.Acharyya Eds.) Cambridge University Press World and Regional Geology Series 10: 1-7. 85. Astre, G, 1934. La Faune Permienne des Gres a Productus d'Ankitokazo dans le Nord Madagascar. Madagascar Annales Geologiques du Service des Mines Fascicle 4: 63-93. 86. Halstead, L.B., 1981. The northern shore of Gondwanaland in Tunisia. In Second Gondwana Symposium Proceedings and Papers (S.H.Haughton, ed.): 193-196. Geological Society of South Africa, Marshalltown. 87. Vijaya, Kumar, S., Singh, M.P. and Tiwari, R.S., 1988. A Middle to Late Triassic Palynoflora from the Kalpani Limestone Formation, Malla Johar area, Tethys Himalaya, India. Review of Palaeobotany and Palynology 54: 55-83.

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Persian-Triassic Evolution of Tethysand WesternCircum-Pacific H. Yin, J.M. Dickins, G.R. Shi and J. Tong (Editors) 92000 ElsevierScienceB.V. All rightsreserved.

271

Magnetic susceptibility and organic carbon isotopes of sediments across some marine and terrestrial Permo-Triassic boundaries H.J. HANSEN a, S. LOJEN and A. SARKAR e

b, p. TOFT a, T. DOLENEC b, Jinnan TONG c, P. MICHAELSEN d

aGeological Institute, University of Copenhagen, Denmark. bJosef Stefan Institute, Ljubljana, Slovenia. cChina University of Geosciences, Wuhan, R R. China. dEarth Sciences, James Cook University, Townsville, Australia. eIndian Schoool of Mines, Dhanbad, India.

This study reports the magnetic susceptibility pattern, as well as organic carbon isotopes, from seven Permo-Triassic sections. The material in four marine sections originates from Meishan, (E. China), Shangsi, (W. China), Idrija and Karavanke (Slovenia) while the three terrestrial series are from Jimsar (NW China), Banspetali (Bihar, India) and Newlands Coal Mine, (Bowen Basin, NE Australia). Time-frequency analysis of the curves of magnetic susceptibility suggest that the pulses registered belong to the Milankovic band representing 20, 40 and 100 kyr cycles. The patterns observed are recognizable in both marine and terrestrial sections and allow correlation between the various sections with a time resolution of 10 kyr. Various biota can thesreby be placed relative to each other with high-resolution age estimates. We suggest that the Permo-Triassic boundary should be placed early in a characteristic magnetic susceptibility pulse which occurs in the center of the biotic changes and which is recognizable in both marine and terrestrial sections. It also coincides with the change in terrestrial biota as well as with a negative carbon isotopic anomaly. The high resolution pattern in organic carbon isotopic signals can in some cases also be correlated between marine and terrestrial sections. The suggested boundary is coincident in the marine sections with a bloom of prasinophyte algae marking the collapse of the marine ecosystem and it is an obvious candidate for an event-marker horizon for the P/T boundary.

1. INTRODUCTION Much current interest is focussed on the Permian-Triassic mass-extinction boundary, not only to understand the mechanisms lying behind the mass-extinction, but also because a boundary stratotype has not yet been fixed. Consequently, considerable research has been undertaken on the biostratigraphy, geochemistry and sedimentology of possible candidate sections [1], but a solution is bedevilled by a variety of problems. For example biostratigraphical markers may be diachronuous, geochemical horizons, such as iridiumanomalies, have proved irrelevant, paleomagnetic signals are, in many instances, subject to later overprinting and oxygen and carbon isotopes based upon carbonates are potentionally

272 influenced by diagenesis. There is an urgent need for a method, which is independent of these uncertainties and which will allow high-resolution correlation between marine and terrestrial series. Magnetic susceptibility stratigraphy was introduced in 1993 [2] for problems of highresolution stratigraphy around the Cretaceous-Tertiary boundary, and the same principles and working methods are here applied to the Permo-Triassic boundary. In addition because strong discrepacies between organic carbon-isotopes and carbonate isotopes from identical samples were found, a high-resolution organic carbon isotopic study was also initiated. In contrast to the carbonate isotopes, carbon from soot and charcoal is to a lesser degree subject to diagenetic alteration, and although the carbon may be oxydized major changes in isotopic composition are unlikely. Accordingly, only organic carbon isotopes have been studied. Furthermore, in terrestrial series, where carbonates are absent, this is the only method available. The pattern of magnetic susceptibility believed to reflect the Milankovic cycles was used as a basis for selecting samples for organic carbon isotopes, so that age resolution for the isotopic changes is assumed to be around 20 kyr. In previous studies [2], the pattern of magnetic susceptibility variation of sediments from a time interval in the Uppermost Maastrichtian constrained by magnetostratigraphy and biostratigraphy, supported an interpretation of the pattern as reflecting Milankovic cycles. Moreover, the pulse pattern was found to be characteristic and recognizable over long distances and in both marine and terrestrial sedimentary series. Commensurate results were obtained by analysis of colour variations in deep sea cores from the corresponding stratigraphic interval [3]. A study of the variation of carbonate content and magnetic susceptibility over the same time interval from NE Spain also suggested that the variation observed was linked to Milankovic cycles [4]. In these Upper Maastrichtian studies, the pattern consists of larger and smaller susceptibility peaks, with the former interpreted as representing 100 kyr cycles. Each of these is separated by 4-5 smaller peaks which were interpreted as 20 kyr cycles [2]. The pattern around the Permo-Triassic boundary is less obvious with respect to larger and smaller pulses, and we are not able, by visual inspection, to discriminate safely between larger and smaller pulses. The complete curve of magnetic susceptibility from the terrestrial series at Jimsar (Figs. 9 and 17) was subjected to time-frequency analysis using the Blackman - Tukey method [5]. The resultant power spectrum is shown in Fig 1. A precondition for a useful timeseries anlysis is a time axis, where the time increments are identical. A detail of the curve from Jimsar (Fig 2) clearly demonstrates (judging from the thickness of the pulses), that this criterion is not met. By selecting intervals from the Jimsar curve where the pulse pattern was well defined we were able to correct for the changes in accumulation rate by adjusting the pulse thickness to the same average value using interpolation in the intervals where the pulses were less well defined. We thereby circumvent the problem of varying accumulation rate. The corrected spectrum was analyzed and the resultant power-spectrum (Fig 3) allows recognition of Milankovic cycles. We assume that the pulses registered in the different sections represent Milankovic cycles, of which the shortest would be the precession with an approximate duration of 20 kyr. Furthermore, we have estimated the accumulation rate through time expressed as sediment thickness per pulse. While admitting that we cannot by visual inspection resol.ve the 20, 40 and 100 kyr cycles of the Milankovic band file shortest pulse is likely to be the dominant one and our proxy is probably slightly underestimated.

273

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274 To correlate the patterns of magnetic susceptibility of the sedimentary series between the various sampled sections, we have numbered every peak, both down- and up-section from the Permo-Triassic boundary.

2. M A T E R I A L S AND M E T H O D S Samples were collected using either knife or a chain-saw equipped with a 30 cm cutting disc reinforced with diamonds. Sample equidistance was determined by bed thicknesses as observed in the field. Ideally, sampling was done so that, whenever possible, a bed was represented by 10 samples. The partly silicified Upper Permian limestones were cut into blocks with rectangular crosssection. In the laboratory they were cut into 7 mm slices parallel to the bedding resulting in 3 mm of each slice being lost in the cutting process. The samples were crushed into pieces smaller than 1 cm, placed in medical plastic vials and measured for their magnetic susceptibility using a KLY-2 Kappa-bridge (Geofyzika, Brno). The values obtained were recalculated into SI units and plotted against stratigraphic height. Organic carbon isotopes were measured on an Europa 20-20 stable isotope analyzer connected to an ANCA SL preparation module housed in the Josef Stefan Institute of Environmental Sciences, Ljubljana, Slovenia. The analytical error is +/- 0.15 0/00 PDB. The samples for organic carbon isotopes were crushed, powdered in an agate mortar, treated with boiling dilute HC1 followed by two digestions in 40% HF in teflon beakers to dryness. Finally repeated boiling in dilute HC1 ensured dissolution of salts precipited during the digestion, after which the residues were repeatedly spun in double distilled water in a centrifuge at 2.000 r.p.m, for 5 min. The clean residues were poured into glazed porcelain jars and dried at 70 degrees C, after which the material was mechanically removed with a Ni-spathula. When the amount of carbon was too low for mechanical removal, the concentrates were pipetted into small aluminum containers and dried. The aluminum container with its contents was then processed in a standard preparational vacuum line. When centrifuging residues, the carbon often refused to settle in the tube when the ionic strength of the liquid became low. At this stage one drop of chemically pure HC1 was added in order to make the carbon settle. Before analysis, the dry carbon concentrates were roasted under vacuum for 20 minutes at 150 degrees C, evaporating the HC1 and leaving a chemically neutral sample.

3. OBSERVATIONS

3.1 Meishan, East China. The section at Meishan has been described in detail [1]. The section is well-exposed and easy to access. In addition to 4 m of continuous "coring" of the uppermost Permian carbonate beds, samples for carbon isotope study were collected farther down-section for 14 m with a spacing of 25 cm. The lowermost 6 m of Triassic deposits were sampled with a spacing of 2 cm. Closer sampling was not possible using a knife in the clayey sediments. Figs 5, 12-13 and 20 show the plots of magnetic susceptibility and organic carbon isotopes.

275 The lowermost part of the section in its carbon isotopes shows a long-term general decrease in 13C (Fig 12). This agrees well with other records [6] which demonstrated a general long-term decline of the 13C signal. This is, however, of limited correlational value and must be assigned to the secular variations recorded by authors (op. cit). The carbon isotopic signal in the lower 14 m of the Permian, in addition to long-term trends, also shows minor short-time fluctuations, which, using the susceptibility pattern as the basis for estimates of the accumulation rate, appear to have a Milankovic periodicity of 400 kyr years. A change towards more negative isotopic values takes place 300 100 - + - Loess ~ Shangsi kyr before the P-T boundary and ends 90just before bed 27. 80The Triassic part shows short, 70negative excursions in ~3C values. Some 60of them can be correlated to other 50sections studied by us, and we therefore 40regard the excursions as real, and not just 30noise. They each have a duration of about 20-40 kyr. With the less dense 20sampling made by previous authors [1,7], 10the chance of finding these short-time 0 I I I IIIII I I I I IIII fluctuations is small and it is therefore 0.01 0.1 0.001 Grain size mm difficult to compare the results. Sediment accumulation rate in the topmost Permian is 38 cm/100 kyr while Fig.4 Grainsize distribution curve of Lower it is 46 cm/100 kyr in the Triassic. We Triassic Bed 28c at Shangsi and Holocene loess observe no changes in the accumulation from Yixin, Zhejiang, East China. rate below the boundary level.

3.2 Shangsi, West China. This section too has been described in detail in the literature [1, 8]. The Upper Permian limestones were sampled continuously for 4 m while 3,5 m of the Lower Triassic were sampled with a resolution of 2 cm. The magnetic susceptibility and organic carbon isotopes are shown in Figs 6 and 14. In bed 28c the sediment was described as "yellowish green silty illite claystone" [1] while the texture to the hand is much like Quaternary loess. A sample was analysed for grain size and the grain curve (Fig. 4) can hardly be distinguished from a sample of Holocene loess from Yixin, Zhejiang Province, East China. We suggest that this bed is an aeolian, but water-lain, deposit. The Permian accumulation rate is 39 cm/100 kyr, which changes to 43cm/100 kyr in the Triassic. Again we see no change in accumulation rate before the P-T boundary. 3.3 Idrija, Slovenia. This section has its Upper Permian developed as indistictly bedded, nodular black limestone [9]. About 5 m below the Permo-Triassic boundary, the limestone is clearly bedded. The transition to the overlying Triassic beds is marked by a thin clayey horizon overlain a few cm upwards by several, even thinner, clayey horizons. The Triassic is developed as wellbedded, light grey limestones. The Upper 1,8 m of the Permian and the lower 2 m of the

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284 Triassic, were sampled as a continuous section, with a stratigraphic resolution of 1 cm. The magnetic susceptibility pattern, along with the organic carbon isotopic values are shown in Figs 7 and 15. The susceptibility pattern allows good correlation with the Karavanke and Jimsar sections. The accumulation rate at Idrija is about 32 cm/100 kyr in the bulk of the Permian part but is reduced to 6 cm/100 kyr in the uppermost Permian. In addition a hiatus may be present between the two sequences. The Triassic accumulation rate is 28 cm/100 kyr. The clay layer, which marks the Permo-Triassic boundary, contains magnetite infilled prasinophyte algal skeletons. 3.4 Karavanke, Slovenia. The section at Karavanke was described in 1986 [6]. It was sampled with a resolution of 2 cm and the section exposes Uppermost Permian and Lowermost Triassic marine deposits where there is a prominent colour change around the boundary. The Lowermost Triassic has impressions after gypsum crystals. The Triassic is deep red, which changes into olive higher in the section. Below the 5 m clayey shale-like Permian strata covered by our sampling, the rocks are developed as thin, well-bedded dolomites. The magnetic susceptibility pattern of the shallow water series represented by the Permian shows a clear pattern which can confidently be correlated with other sections. In particular, the correlation with the terrestrial section at Jimsar is good (Figs 8 and 16). We interpret this as an indication of strong terrestrial sedimentary influence upon the environment in the youngest marine Permian at Karavanke. Organic carbon isotopes show two negative anomalies in the latest Permian. The accumulation rate in the Permian part is around 57 cm/100 kyr, but the final section shortly before the P/T boundary, appears to have a reduced accumulation rate of 41 cm/100 kyr. This is reminiscent of the marine Idrija and terrestrial Jimsar sections. The Triassic section at Karavanke has an accumulation rate of 60 cm/100 kyr, with no apparent change over the sampled interval. 3.5 Jimsar, NW China. This section, exposing terrestrial Permo-Triassic sediments, was described in Sweet and by Yang et al. [8, 10]. These authors found the palynological, as well as vertebrate-based P/T boundary, to lie 20-30 m below the boundary between the Goudikeng and the overlying Jincaiyuan formations (i.e. inside the Goudikeng Formation). The formational and lithological boundary is clearly marked in the field by a prominent colour change, where the younger formation weathers "Triassic red". However, the magnetic susceptibility, as well as carbon isotopic pattern, clearly corroborates the findings of the paleontologists. (Figs 9 and 17). We observed that both the strike and dip of the exposed series change a short distance below the P/T boundary. This has not been recorded in the literature, and we are uncertain of its significanse which warrants further investigations. The accumulation rate in the Permian is around 560 cm/100 kyr, which decreases to 375 cm/100 kyr in the very latest Permian. The Triassic has an accumulation rate of 450 cm/100 kyr, with no apparent changes over the sampled interval. Carbon isotopes show two prominent negative anomalies in the Uppermost Permian, while in the Triassic, values show a long-term shift towards less negative values up-section. However, the curve is not smooth, containing many short negative excursions.

285

3.6 Banspetali, India. The Banspetali locality lies in the Indian Province of Bihar, about 160 km WNW of Calcutta. It exposes 6 m of Uppermost Permian mudstones and shales with a short, car bonaceous shale interval. It is overlain by 5,5 m sandstone representing an extensive meandering river system and higher up by 9 m of yellow sands with thin, intercalated pebble horizons. The latter is clearly of braided fluvial origin, but 4 of the 9 m are not well-exposed. The upper part consists of a mudstone sequence 4,5 m thick, overlain by 8 m of yellow sand, of which the lower 4 m are well-exposed. The section terminates in a 3 m mudstone. The magnetic susceptibility pattern, along with isotopes, are shown in Figs 10 and 19. The Permian part is incomplete and it appears from the susceptibility and isotopic curves that 15 precessional cycles are missing. The accumulation rate is around 165 cm/100 kyr, which is rather low for terrestrial deposits. The missing interval corresponds well to the erosional depth of the meandering river. This suggests that the final fill of the river took place close to the Permo-Triassic boundary. Although short, the magnetic susceptibility of the Triassic mudstone part appears to correspond well with that of the Triassic sequence from Meishan (Figs 19 and 20). The isotopic samples at 3500 and 3525 cm on the plot are from rip-up clasts of mudstone in the sandstone. 3.7 Newlands Coal Mine, NE Australia. The Newlands open cut mine exposes 23 m Upper Permian sequence of lacustrine, carbonaceous mudstone interbedded with laterally restricted crevasse sandstone sheets. The sandstone from 10 to 14 m on the plot was inaccesable while the mudstones and overlying sandstones were sampled. The mudstone from 6 to 10 m is regionally developed and is locally known as the "Marker Mudstone". It is taken to represent the topmost Permian. The sandstone complex from 0 to -15 m is of braided origin and is strongly reminiscent of the situation at the Banspetali section, India. The braided sandstone contains in its lower part numerous, larger, redeposited plant debris. The pattern of magnetic susceptibility as well as carbon isotopes (Figs 11 and 18) do not contradict the Uppermost Permian age suggested for the "Marker Mudstone". The isotopic pattern just below the P-T boundary agrees well with a previous report from the Bowen Basin [11]. The Triassic mudstone interval from 0-1,5 m is too short to make a safe correlation with other sections. The crevasse splay sandstone from 1,5 to 6 m may well have been deposited in Uppermost Permian time in view of the very negative carbon isotopic value found in its uppermost part. The accumulation rate in the latest Permian is 142 cm/100 kyr cm while it is around 100 cm/100 kyr further down-section. The Triassic part can not be estimated with respect to accumulation rate, because of the very short section. 3.8 Spherules Spherules have been mentioned from various Chinese marine Permo-Triassic boundaries such as Meishan, Shangsi, Ermen and Kejiawan (in Huangshi, Hubei Province) [1, 8]. Spherules occur in bed 25 and 26 of the Meishan section and in their lateral equivalents at the other sections. Bed 25 is a rhyolitic bentonite, which can be followed everywhere across south China in the P/T boundary sections. The presence of hexagonal bipyramids of low quartz with glass inclusions is conclusive evidence of its rhyolitic origin [12]. From the bentonite,

286 spherules with well-known volcanic features such as tapering droplets, vesicles, contractive wrinkles, spiral filaments etc. have been recorded [8]. In addition, bedding-planes in the bentonite at Kejiawan, were covered with skeletons of compressed prasinophyte algae, lying so close together, that they, through the compression, acquired a polygonal outline. They are sufficiently well-preserved to allow biological fixation and ultrasectioning (Hansen, unpublished). Their presence indicates, that the algae were blooming at the time of the deposition of bed 25 (the rhyolitic bentonite). In bed 26 at Meishan and other localities, the sediment is developed as an organic-rich layer containing plenty of elementary carbon causing its black colour. It is strongly reminiscent of the Fish Clay at the Cretaceous-Tertiary boundary by its black colour and numerous compressed burrow-fills, giving the impression, that it is bedded. In addition to spherules also found in the underlying bentonite (bed 25) it contains a considerable amount of diagenetically infilled algal skeletons. The infill consists of magnetite which carry various trace elements such as Cr and Mn but never Ni, as found in the magnetite infill of prasinophyte algae at the KiT boundary at Gubbio, Italy (Hansen, unpublished). The diameter of the algae ranges from 40 to more than 100 microns. The magnetite may be skeletal and even monocrystalline as seen in a spherical octahedron (Fig 21). Some are preserved within their encasing alga, while others are slightly corroded. So far, we have found them in black boundary clay where we have searched: Idrija, Shangsi, Meishan, Huangshi and Tesero, north Italy. At Tesero [9], in a clay horizon lying directly on top of the Bellerophon Limestone, we also found fractured specimens, which showed the central part to be filled by whitish material, while the magnetite formed the outer sphere. The spheres are rarely deformed, pointing to an early infill prior to compaction of the surrounding sediment.

Fig. 21. Magnetite infilled prasinophyte algae A: From clay layer on top of Bellerophon Limestone, Tesero, Italy. Diameter 45 microns. B-C: From black boundary clay, Ermen, Huangshi, China. B: Skeletal magnetite. Diameter 40 microns. C: Spherical octahedron. Diameter 38 microns. D: From boundary clay, Idrija, Slovenia. Diameter 125 microns.

4. DISCUSSION AND CONCLUSIONS A characteristic magnetic susceptibility pattern across the suggested P/T boundary is present in all complete sections (Fig 22), and in the marine sequences the proposed boundary lies in a spherule-bearing black clay layer which represents a bloom of prasinophyte algae. At the K/T mass-extinction boundary there was a similar algal bloom which gave rise to

287 diagenetically infilled spheres. The algae were suggested to have bloomed when their predators disappeared during the collaps of the marine ecosystem [13]. An identical mechanism is suggested for the P/T boundary phenomenon and the algal bloom is a potential event marker-bed in the marine realm. The Permo-Triassic boundary should be selected in the vicinity of the occurrence of the various biostratigraphical marker-species. Biostratigraphers have long realized, however, that animal dispersal may cause the appearence of some forms to be diachronous in the stratigraphic record. In spite of this, biostratigraphy still offers one of the better approximations to chronostratigraphy. Discussions regarding a biostratigraphical marker for the Permo-Triassic boundary originally concentrated upon ammonites as having the most useful taphonomy, where drifting empty shells afforded wide dispersal. I-bwever, the efficacy of such a mechanism is obvious. The present inclination towards using the appearance of the conodont Hindeodus parvus in the most cases fulfills the disirability of a suitable marker-organism shortly after the marine (and in our opinion, the terrestrial) PermoTriassic biotic change. However, the marine change does not take place at a single level [1] so that shortly after the extinction event, H. parvus makes its first occurence in bed 27c at Meishan, whereby it satisfies the requirement, that a guide fossil should not appear simultaneous with a lithological change. However, our magnetic susceptibility profiles strongly suggest that H. parvus at the Shangsi section is delayed in its occurrence by 4,5 m corresponding to 1 myr relative to the Meishan section. On the other hand, H. parvus by contrast to other suggested fossils is found at most marine Permo-Triassic boundaries, thereby making it the most useful biotic time marker. In China, with its numerous marine Permo-Triassic boundaries, it is possible to make a true chronostratigraphy using the numerous, widely distributed rhyolitic ash-layers (bentonites). These, in Chinese literature, are often referred to "clay layers". These bentonites are the best tool in true chronostratigraphy. Fig. 22. Characteristic magnetic susceptibility pattern across Permo-Triassic boundaries in four marine and one terrestrial sections. The pattern is characterized by a stepwise drop in values towards the Triassic. The steps are interpreted as precessional cycles.

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288 We have undertaken geochemical typing of various bentonites and have found that they do not differ significantly in trace-elements that are non-labile during the devitrification process.Using INAA we analysed 9 bentonites from Huangshi and 3 from Meishan, and found that they contain rather high values of Ta. The stratigraphical level of bentonites relative to magnetic susceptibility pattern may prove to be a future correlation tool. The traditional Permo-Triassic boundary in Chinese literature lies between bed 25 and 26 in Meishan and the bentonite constituting bed 25 can be identified in most Chinese marine boundary sections. In summary our suggested Permo-Triassic boundary lies below the first occurrence of H. parvus and is situated in a clay bed with mass-occurrence of prasinophyte algae. In addition, it coincides with a negative carbon isotopic anomaly. This anomaly is not unique since a further shorter anomaly is found 350 kyr years previously. Both Permian anomalies are recorded at Jimsar, Karavanke and Idrija. In the Lower Triassic, a series of negative anomalies are found, some of which appear both in marine and terrestrial sections. Many of the marine sections may record in their carbon isotopes a mixture of marine and terrestrial carbon related to differences in run-off from the land. However, the terrestrial profiles do not suffer from this weakness. When consequently the same pattern is registered in both terrestrial and marine sections, cognisance can be placed in the former. The aeolian contribution at Shangsi is a reminder, that missing negative excursions at this section may be due to the introduction of redeposited, geologically older, carbon. The mass-extinction at the Permo-Triassic boundary, which is the largest known in earth history, has no connections to extra-terrrestrial causes. There is disagreement as to whether or not the P/T boundary was coincident with a transgression or a regression [14]. The section at Selong, Tibet, contains a caliche at the boundary in an otherwise shallow marine deposit [ 1]. Moreover, the Slovenian section at Karavanke, which is also a shallow marine series, records gypsum impressions in the lowermost Triassic indicating regression. Reduced accumulation rates found shortly before the P/T boundary in Jimsar, Karavanke and Idrija also suggest cooling, in view of the reduced precipitation associated with lower accumulation rates. As pointed out by Erwin [ 11, and references therein] it appears that the Chinese marine sections are unusual, in not recording the regression clearly found in other parts of the world. This further supports the suggestion as to a Chinese marine section for the boundary stratotype. Erosional unconformities throughout south China recently suggested [15] have not been observed by us. Also the discussion of the negative carbon isotopic anomaly at the PermoTriassic boundary and its cause appears less relevant in view of the repeated anomalies found by the present authors.

ACKNOWLEDGEMENTS The present investigation was made possible through a grant from the Danish Natural Science Research Council (grant no. 9503582). The project was also supported by the Josef Stefan Institute, Ljubljana, Slovenia, Geological Survey of India, Indian School of Mines, Dhanbad, as well as the James Cook University, Townsville, Australia. Dr. Liu Qingshen, China University of Geosciences, Wuhan, aided in collecting the Triassic part of the Meishan section. Cand. jur. H. Rasmussen helped sampling the Banspetali section. For logistic support we owe a debt of gratitude to the Geological Survey of Xinjiang, Urumqi, China. Our friend student Matej Dolenec kindly assisted in the sampling at Idrija and Karavanke. The

289

Geological Institute, University of Copenhagen, made numerous contributions to the project in addition to placing their facilities at our disposal. Dr. R.V. Dingle kindly suggested improvements of the text.

REFERENCES

1.

2.

3.

4. 5. 6.

7.

8.

9. 10.

11. 12.

13. 14. 15.

Yin Hongfu (ed.), The Palaeozoic-Mesozoic boundary candidates of global stratotype section and point of the Permian-Triassic boundary, p. 1-137, (1996), China University of Geosciences Press, Wuhan, China. Hansen, H. J., Rasmussen, K. L., Liu Qingsheng and 4 others, Correlation of marine and terrestrial Upper Cretaceous sediments by their magnetic susceptibility. Bull. geol. Soc., Denmark, 40 (1993) 175-184. Hansen, H. J., Toft, P., Mohabey, D. M. and Sarkar, A., Lameta age: Dating the main pulse of the Deccan Traps. Gondwana Geol. Mag., Spec. vol. 2, (1996) 365-374. Herbert, T. D. and D_Hondt, Precessional climate cyclicity in Late Cretaceous - Early Tertiary marine sediments: a high resolution chronometer of Cretaceous-Tertiary boundary events. Earth and Planetary Science Letters, 99, (1990) 263-275. ten Kate, W. G. H. Z., and Sprenger, A., Orbital cyclicities above and below the Cretaceous/Paleogene boundary at Zumaya (N Spain), Agost and Relleu (SE Spain). Sediment. Geol., 87 (1993) 69-101. Blackman, R. B. and Tukey, J. W., The measurement of power spectra.. 190 pp, (1958), Dover Publications Inc., New York, N.Y., U.S.A. Veizer, J., Holser, W. T. and Wilgus, C. K., Correlation of 13C/12C and 34S/32S secular variations. Geochimica et Cosmochimica Acta, 44 (1980) 579-587. Gruszczynski, M., Hoffman, A. and Malkowski, K., A brachiopod calcite record of the oceanic carbon and oxygen isotopes hofts at the Permian-Triassic transition. Nature, 337 (1989) 64-68. Gruszczynski, M., Hoffman, A., Malkowski, K. and 3 others, Carbon isotopic drop across the Permian-Triassic boundary in SE Sichuan, China. N. Jb. Geol. Pal_ont. Mh., 10 (1990) 600-606. Chen Jin-Shi, Chu Xue-Lei, Shao Mao-Rong and Zhong Hua, Carbon isotopic study of the PermianTriassic boundary sequences in China. Chemical Geology (Isotope Geoscience Section), 89 (1991) 239-251. Sweet, W. C., Yang Zunyi, Dickins, J. M. and Yin Hongfu (eds.) 1992: Permo-Triassic events in the Eastern Tethys. World and Regional Geology 2, (1992) 1-181, Cambridge University Press. China IGCP National Committee, Field Guide-book. The final conference on Permo-Triassic events of East Tethys Region and their intercontinental Correlations. (1987) Beijing, China. Italian IGCP 203 Group (eds.), Field guide-book. Permian and Permian-Triassic Boundary in the South-Alpine segment of the Western Tethys. (1986) 1-179. Societa Geologica Italiana. Brescia, Italy. Yang Jiduan, Qu Lifan, Zhou Huiqin and 9 others, Permian and Triassic strata and fossil assemblages in the Dalongkou area of Jimsar, Xinjiang. Geol. Mem., ser. 3, (1986) 1-235 (in Chinese with English abstract). Morante, R., Veevers, J. J., Andrew, A. S. and Hamilton, P. J., Determination of the Permian-Triassic boundary in Australia from carbon isotope stratigraphy. APEA Journal, (1994) 330-336. Bohor, B. F., Triplehorn, D. M., Tonsteins; altered volcanic ash-layers in coal-bearing sequences. Geol. Soc. Amer., Spec. Pap. 285 (1993) 1-44. Kalb, G. And Klotsch, H., Die Kristalltracht des Hochquarzes in minerogenetischer Betrachtung. Zentralbl. Mineral. Geol. Paleont. Abt. A, (1941) 66-72. Hansen, H. J., Gwozdz, R., Bromley, R. G. and 3 others, Cretaceous-Tertiary boundary spherules from Denmark, New Zealand, and Spain. Bull. geol. Soc. Denmark. 35 (1986) 75-82. Erwin, D. H., The great Paleozoic crisis. (1993) Columbia University Press, New York. Bowring, S. A.,Erwin, D. H., Jin, Y. G., Martin, M. W., Davidek, K. and Wang W., U/Pb zircon geochronology and tempo of the End-Permian mass extinction. Science, 280 (1998) 1039-1045.

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Persian-Triassic Evolutionof Tethys and WesternCircum-Pacific H. Yin, J.M. Dickins, G.R. Shi and J. Tong (Editors) o 2000 ElsevierScienceB.V. All rights reserved.

291

Evolution of the Permian and Triassic Foraminifera in South China* Jinnan TONG a and G. R. SHI b a b

Faculty of Earth Science, China University of Geosciences, Wuhan 430074, China School of Ecology and Environment, Deakin University, Rusden Campus, 662 Blackburn Rd., Clayton, VIC 3168, Australia

An analysis of Permian foraminifera of South China suggests two major episodes of mass extinction, which occurred respectively at the end-Guadalupian and end-Lopingian. However, these two events of mass extinction appear to have affected different groups. The recovery of the foraminiferal faunas in the Triassic commenced nearly 10 million years later after the endPermian mass extinction, and the genuine Mesozoic ecosystem did not fully emerge until Late Triassic time. The various foraminiferal groups of different wall structures and compositions of tests had very distinctive evolutions during the Permian-Triassic transition. The PermoTriassic events resulted in the most significant transformation in the history of the Foraminiferida, that is, the alteration from the Late Paleozoic calcareous microgranular groups to the Mesozoic-Cenozoic hyaline, perforate, calcareous forms.

1. I N T R O D U C T I O N The geological events around the Paleozoic-Mesozoic transition brought about an important saltation in the foraminiferal evolution, resulting in most of the prosperous Late Paleozoic groups withdrawn from the ecosystem and hence vacating an ecospace for the development of the Mesozoic groups. During this transition, not only fusulinid foraminifera became extinct, but most of the calcareous, microgranular forms were also annihilated, along with many Paleozoic forms of porcelaneous foraminifera. Accompanying these extinction events, some Mesozoic forms had their ancestors originating in the latest Paleozoic and strode over the Permian-Triassic boundary. For instance, the hyaline, perforate, calcareous foraminifera originated in the Late Paleozoic with only a few genera and species of nodosarians which bestrode the Permian and Triassic boundary, they were well developed and became dominant in the Mesozoic and especially the Cenozoic and recent oceans. The agglutinated group is the largest and most important among the foraminifers surviving the end-Permian mass extinction [1]. The Paleozoic and early Mesozoic agglutinated members were mostly opportunistic forms with specialized abilities to fit into various high-pressed dynamic conditions [2], thus they generally had no notable adaptive divergence but extraordinarily high abundance in some specific stratigraphic horizons. As a matter of fact, those who predominated in the Paleozoic faunas and outlived the mass extinction were mostly ammodiscids and some rudimentary lituolid elements. No fossil records of proteinaceous or pseudochitinous forms have been * This research is sponsored by support of the National Natural Science Foundation of China (No. 49502022, 49632070) (to JNT) and the Australian Research Council (to GRS).

292 reported from the Permian and Triassic though Eisenack [3 ] did describe Archaeochitosa from both the Silurian and Jurassic, which has led Loeblich and Tappan [4, 5] deduce its existence in the Permian and Triassic. Foraminifera at the beginning of the Triassic were very stagnant, with very few known species. More foraminifers were discovered from the late Early Triassic, many of which represent a further development of the simple forms astride the Permian and Triassic boundary. Some that had been adapted to high-pressed conditions were branching out into normal marine environments. The Middle Triassic foraminifera had further development, especially the perforate forms which increased considerably in diversity and abundance. But the real maturation of the Mesozoic foraminiferal faunas did not occur until the Late Triassic. The evolution and turnover of the foraminiferal faunas across the Permian-Triassic boundary were associated with many other geological events. It is possible that at least some of these events, particularly environmental deterioration, may have destroyed to a great extent the ecosystem in which the Late Paleozoic foraminifers lived in, resulting in both a reduction in diversity and also an almost complete change in taxonomic composition of the Foraminiferida. On the other hand, both the physical and biological revolution across the Permian-Triassic boundary also created an opportunity for the recovery and re-establishment of foraminifera in the Mesozoic, following a period of aftermath lasting nearly 10 million years [1, 6].

2. PERMIAN AND TRIASSIC CARBONATE FACIES IN SOUTH CHINA Paleozoic and Triassic foraminifera are known mainly from thin-sections of carbonate rocks. Though some specimens have been reported from clastic or other non-carbonate rocks, they are generally very rare in these facies. The stereo fossils are of great value in the study of foraminifera but their identification (including fusulinids) has mostly been based upon thinsections. The existence of marine carbonate facies is therefore the precondition for the study of foraminifera during the Permian and Triassic. At the beginning of the Permian (Cisuralian) shallow-water carbonate facies were widespread across South China (e.g. Chuanshan Fm, Maping Fm and others, see Table 1). But at one time in the late Cisuralian (early Chihsian) most of South China (the Yangtze Platform) was uplifted and subject to erosion, resulting in the deposition of coal-bearing clastic sediments (i.e. Liangshan Fm). The foraminifer-enriched carbonate rocks existed only in some localized depressions (e.g., the Nanjing-Zhenjiang area, and South Guizhou-North Guangxi area). The middle and upper Chihsian carbonate rocks could be traced all over South China with little discernible lithological variation. Deposition of similar carbonate facies persisted into the Maokouan, accompanied by the peak development of various shallow marine faunas until the late Maokouan when the sea-level began to fall. Preceding the sealevel drop, differentiation of various paleogeographic settings caused by tectonic effects had occurred from the beginning of the Maokouan. As a result, some areas became downwarped in the early Maokouan, in which the Gufeng Formation-type relatively deep-water siliceous sediments accumulated. Sea-level fell in the late Maokouan, yielding Yanqiao Formation and Yinping Formation of clastic rocks. A global regression occurred at the end of the Guadalupian [7], giving rise to a sharp reduction in carbonate deposition. In South China, however, carbonate sedimentation continued well into the Wuchiapingian in many parts of the Middle and Upper Yangtze regions, producing the Wujiaping Formation. The Late Permian

293 Table 1 Permian and Triassic chronostratigraphy and some carbonate units in South China System

Series

Global stage

South China stage

Upper

RhaetianCarnian

RhaetianCarnian

Baijizu Fm (Yunnan), Ma'antan Fm (Sichuan)

Ladinian

Ladinian

YangliujinFm (Guizhou)

Anisian

Anisian

Guangling Fm (Guizhou), Qingyan Fm (Guizhou)

Olenekian

Olenekian

Induan

Induan

Changhsingian

Changhsingian* (Changxingian)

Wuchiapingian

Wuchiapingian* (Wujiapingian) Wujiaping Fm (Upper Yangtze region)

Middle Triassic

Lower

Lopingian

Some foraminifer-bearing carbonate units

Jialingjiang Fm (Sichuan, Hubei), Nanlinghu Fm (Anhui, Jiangsu) Daye Fm (Hunan), Feixianguan Fm (Sichuan) Changxing Fm (South China)

Capitanian Permian

Guadalupian

Wordian

Maokouan

Maokou Fm (South China)

Roadian Kungurian Cisuralian

Artinskian Sakmarian Asselian

Chihsian* (Qixian) Longlinian Zisongian

Qixia Fm (South China) Baomoshan Fm (Guizhou), Changme Fm (Guangxi), Chuanshan Fm (Lower Yangtze region), Maping Fm (Guangxi, Yunnan)

* In the early Chinese pinyin "Changxing" was spelt as "Changhsing", which is not used now in China except for in Taiwan and, probably, Hong Kong and Macaw. Likewise, "Wujiaping" was spelt as "Wuchiaping", "Qixia" as "Chihsia", "Gufeng" as "Kuhfeng", and so on. Considering that "Changhsingian", "Wuchiapingian" and "Chihsian" have been used in the Permian chronostratigraphic table [9, 10], we keep using these terms in this paper, but we use present Chinese pinyin in the other cases such as in lithostratigraphy.

Changxing Formation, a predominantly carbonate unit with abundant foraminiferal fossils, is recognizable in many areas of South China and appears to signal the final transgression of the Paleozoic [8]. However, the Permian-Triassic transition was punctuated by a period of no carbonate sedimentation. The non-carbonate horizon of Bed 25 and/or Bed 26 at Meishan section [11 ] can be well traced both in South China [12] and globally [13]. Whether or not this phenomenon is directly related to the Permo-Triassic mass extinction requires further investigation. But the carbonate rocks below and above this non-carbonate bed are much altered and their biotas are entirely different to each other. This bed is typically thin in South

294 80 706050txo

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9

........

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Guadalupian

Changhsin#au

Lopingian

Figure l. Origination, extinction and diversity of fusulinid genera based upon the data of Sheng et al. (1988) [18] (see Table 1 for the relationship between the stages used in South China and the global stages)

China (usually < 20 cm). The carbonate strata immediately above this bed are however widespread over whole South China [12]. By contrast, the overlying lower Griesbachian strata are characterized by fine clastic and argillaceous rocks and, where carbonate rocks do exist, they are largely micritic limestones. In the upper Griesbachian argillaceous rocks decrease remarkably, seemingly at the expenses of increasing carbonates. It is notable that the increase of carbonates into the upper Griesbachian does not appear to have been accompanied by any significant changes in paleogeographic settings. Affected by the Indosinian Movement, major sedimentary basins on the Yangtze Platform started shrinking from the late Early Triassic, resulting in carbonate evaporites first formed in the Anisian, succeeded by terrestrial facies in the Ladinian and later. Accompanying with the lithological changes was a clear lithogeographic differentiation that occurred particularly at the margins of the platform where carbonate sedimentation persisted into the Late Triassic. However, although the various Triassic carbonate facies may be compared with those of the Late Paleozoic, the features of the foraminiferal faunas are totally different, in both taxonomic and community composition, abundance, and diversity. In summary, South China has not only the uppermost Paleozoic foraminifer-rich carbonate formations, but also the continuous Paleozoic-Mesozoic sedimentary sequences, the lowermost Mesozoic carbonate rocks, and varied paleogeographic settings. As such, South China is a key area to study the biotic evolution of benthic groups (including foraminifera) across the Paleozoic and Mesozoic transition. The development of the Foraminiferida appears closely related to its ecological variation. The ecological adaptation results in fluxion of the structure and morphology of the foraminiferal tests. The features of the tests commonly serving as the basement of the classification of the Foraminiferida [4, 5, 14] directly reflect their living environments and their adaptation to various ecological conditions [15]. The characteristic Late Paleozoic

295 microgranular foraminifera (including fusulinids) were normal marine benthos and would have made important contribution to the carbonate sedimentation at that time. However, further development and survival of this group at the close of the Paleozoic was prohibited by the severe reduction of marine shelf areas caused by the integration of the supercontinent Pangea [16] and, also possibly, the spread of extensive anoxic marine waters [ 17]. With the re-occurrence of carbonate facies at the beginning of the Triassic, some eurytopic forms such as the agglutinated ammodiscids immediately came back. The surviving porcelaneous and perforate members, mostly spirillinids, also begin to diversify at the same time. Thus, in view of the historic development of the Late Paleozoic-Triassic foraminifera outlined above, it seems clear that the evolutionary processes of foraminifera did not only reflect on the improvement of their biologic/morphologic structures, but also, to some extent, symbolize the effect of contemporary paleoecologic and paleogeographic conditions on the evolution of marine benthos (including foraminifera).

3. DISTRIBUTION OF PERMIAN AND TRIASSIC FORAMINIFERA IN SOUTH CHINA The Carboniferous-Permian was the first climax period in the history of the Foraminiferida, characterized by abundant calcareous microgranular forms including fusulinids and some other Paleozoic foraminifers [ 1]. The fusulinids were among the most characteristic Paleozoic foraminifers. Though the fusulinids lived only in the Carboniferous and Permian, they had a rather speedy evolution, first occurring in the early Carboniferous, rapidly expanding and flourishing in the Middle Carboniferous and arriving climax in the early and middle Permian. Thereafter they experienced a rapid and intense extinction at the end of Guadalupian, with only few extraordinary elements surviving into the Lopingian (Figure 1). In South China only 8 genera extended into the late Changhsingian, most of which developed specialized test structures (e.g., Codonofusiella and Reichelina) or walls subject to silicify (e.g., Nankinella and Staffella) [ 1]. In non-fusulinid foraminifera, 491 species of 63 genera have been found in the Permian of South China, in comparison with 275 species of 69 genera reported from the Triassic of the same region (Figure 2). The Permian non-fusulinid foraminifera are strongly dominated by microgranular Endothyrina, especially Endothyracea and the Triassic by perforate Rotaliina, mainly Nodosariacea. The diversity was steadily increasing from the Zisongian to Maokouan and kept very high in the Changhsingian though there was a slight decline in the late Maokouan and Wuchiapingian. A conspicuous drop in diversity occurred in the Induan, followed by an increase in the Olenekian and Anisian (Figure 2). During the Permian, no significant changes in the generic and specific diversity of agglutinated Textulariina are noticeable. By contrast, the porcelaneous Miliolina and perforate Rotaliina were increasing constantly, with the latter group diversifying at even greater rate (Figure 2). Unlike the fusulinids, the diversity of the non-fusulinid foraminifera, especially the endothyrids that were predominant in the Permian, did not decline abruptly at the end of the Guadalupian although they suffered a severe extinction at the end of Changhsingian. However, both fusulinid and non-fusulinid foraminifera demonstrate some comparable evolutionary trends prior to their respective mass extinction. For instance, the Maokouan fusulinids embraced some large forms with complicated septula, such as Neoschwagerinidae. Likewise, the Changhsingian endothyrids also developed specialized morphological

296

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DMilioliina

i I

i I

O l e n Anis

INlRotaliina

I

i

i

,

Lad

]

U.Tri

[-]Total

Figure 2. Diversity of Permian and Triassic non-fusulinid foraminifera in South China ZisIZisongian, LonglILonglinian, Chih--Chihsian, Maok--Maokouan, Wuch Wuchiapingian, ChanghIChanghsingian, IndmInduan, OlenmOlenekian, AnismAnisian, Lad~Ladinian, U.Tri~Upper Triassic (see Table 1 for the relationship between the stages used in South China and the global stages)

297 characters: Colaniellidae with additional septal structures, Pachyploia (and allied genera) with thickerted walls, and Climmacammina, Cribrogenerina, Septoglobivalvulina, Paraglobivalvulina (and many others) with large and unusual tests. Interestingly, most of these specialized forms died out at the end-Changhsingian mass extinction. The Triassic foraminifera were led by rotalians although its superiority in the Triassic was not so apparent as the endothyrids in the Permian. The agglutinated textularians formed an important component of the Triassic foraminiferal faunas, even ascendant in the early Triassic. The rotalians became dominant only from Middle Triassic. Though the porcelaneous miliolinids are common, in some abnormal marine environment [15], they never attained a prevalent position in the Permian or Triassic. Generally speaking, both generic and specific diversities of non-fusulinid foraminifera gradually increased from the early to late stages in both Permian and Triassic; however there was a distinct demarcation in taxonomic composition between the Permian and Triassic predominant groups. In South China, there is hardly any difference in the number of nonfusulinid foraminiferal genera between the Permian and Triassic climax stages, but the Triassic foraminiferal species are clearly less than that of the Permian (Figure 2). This decrease in Triassic foraminiferal species is probably due to the rapid reduction of Middle and Late Triassic carbonate facies in South China [19] (interestingly, Triassic foraminiferal diversity was comparatively high in the western Tethys [20, 21 ]). As shown in Figure 2, the Lower Triassic generic diversity of foraminifera (mostly deduced on the basis of their first and last occurrences) is very low, especially the Induan foraminiferal records which exhibit a worldwide diversity depletion.

4. EXTINCTION OF PERMIAN FORAMINIFERA IN SOUTH CHINA The extinction of Permian foraminifera mainly involved the calcareous microgranular groups. It is interesting to note that the two microgranular groups (fusulinids and endothyrids) became extinct at different stages: with the end-Maokouan extinction mainly involving the fusulinids (Figure 1) and the end-Changhsingian extinction decimating most of the endothyrids (Table 2, Figure3). These two extinction events correspond to similar events recognized from other fossil groups [22]. In fact the extinction of the endothyrids in the Maokouan is not even as high as in the Chihsian (Figure 3). In South China, the end-Maokouan extinction wiped out 86% fusulinid genera (leaving only 8 genera persisting into the Changhsingian), but the same extinction extinguished only 23% genera and 39% species of the non-fusulinid foraminifera, among which 18% genera and 39% species were endothyrids (Figure 3). By comparison, the end-Changhsingian mass extinction resulted in 32 (out of 44) or 73% genera and 205 (out of 218) or 94% non-fusulinid specific extinction, which included 93% genera and all species of the endothyrids. Also of interest to note is that none of the Changhsingian foraminiferal species in South China has been found in the Lower Triassic (except for 13 agglutinated elements). This is in sharp contrast to the fact that 127 Maokouan non-fusulinid foraminiferal species apparently had outlived the endMaokouan extinction. As the data in our database are based on a stage-level qualitative timescale, Figure 4 shows the extinction and origination rates, which are smoothed by the total genera and species in the stages. Due to limited Middle and Late Triassic records and Jurassic marine sediments in South China, the foraminiferal extinction data of South China in our database might be somewhat

298 40-

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Figure 3. Extinction of Permian and Triassic non-fusulinid foraminifera in South China ZisIZisongian, Longl--Longlinian, ChihmChihsian, MaokmMaokouan, WuchWuchiapingian, ChanghmChanghsingian, IndmInduan, Olen~Olenekian, AnisAnisian, LadILadinian (see Table 1 for the relationship between the stages used in South China and the global stages)

299

Table 2 Distribution of the non-fusulinid foraminiferal genera in the Permian and Triassic of South China

Oenus

I

I ong'l hih I

I

hangl Ind Io'en I Anis I ad I . ri

Ammodiscacea

Ammodiscus Brunsia Dichospira Glomospira Hemidiscus Tolypammina Turriglomina Turritellella

+ *

+ *

+ +

+ +

* *

+ +

+ *

+

+

+

+

+ 9

+ +

+

+

+

+

+

+

+

+

+

+

+

+

9

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

*

+

+

Lituolacea

Ammobaculites Ammosiphonia Dagmarita Gaudryina Haplophragmoides Monodorina Palaeolituonella Palaeospiroplectammina Pseudocyclammina? Pseudolituonella? Reophax Textularia Trochammina Verneuilina Verneuilinoides

+ +

+

+ +

+ +

+

+ +

+ + +

+

+ +

Parathuramminacea

I

Earlandinita

I

Endothyracea

Abadehella Baisalina Bradyina Climacammina Colaniella Cribrogenerina Cribrostomum Deckerella Deckerellina Endothyra Endothyranella Eocristellaria Eotuberitina Frondina Geinitzina Globivalvulina Glomospiranella

+

+

+

9

at_

9

+

+ +

+ +

+

+

+

+

+

+

+

9

9

+

+

+

+

+

+

+

+

+

+

+

+

9

+

+

+

+

+ +

,

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

*

+

+

I +

+ +

+

+

+

300

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Genus

Zis

Longl

Chih

Maok

Wuch Chang

Ind

Olen

Anis

Lad ,

Glomospiroides

*

,

+

Hubeirobuloides

+

Krikoumbilica Lasiodiscus Monotaxinoides Multidiscus

, .

+ +

!

1 . .

+ + +

+

+

+.

. .

+

Multifarina Neoarchaediscus

I

!

*

,

* +

9

.

+ +

.

*

.

+.

+.

+

+

"1-

*

+

Neoendothvra__

,

L

+

+

+

Neo~zeinitzina

,

~

+

Neodiscus

!

+

Neotuberitina Nodosinella

,

,

Pachyphloia

,

,

Palaeotextularia

,

+

.

.

+

+

+

+ +

+

+

+

+

+

+

+

+

,

+

+.

. ,

Plectogyra

,

+ i

+

+ +

,

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, +

+

Polytaxis ?

+i

,

i

,

+

+i+

Postendothyra Pseudocolaniella

L

Pseudovidalina

+

,

+

+

+

Robuloides

+

*

+

+

Robustopachyphloia

+

*

+

+

Septagathammina

+

+

+

L +

Quasipadangia

Septoglobivalvulina Tetrataxis

i

!

+ + +

Paracolaniella Paraglobivalvulina

+

+

. .

U.Tri ,

I +

+

+

+

Valvulinella

+

.

+

+

+

+

*

*

+

+

+

+

,

,

9

+

+

+ +

+

+

+

Miliolacea +

Agathammina

+

Bivertella Cornuspira Eoophthalmidium +

Hemigordiopsis Hemigordius

+

+

+

+

Meandrospira

+

Ophthalmidium Palaeomiliolina

Shanita

+ +

+

Paratriasina Pseudoagathammina

+ +

+

+ +

Sinophthalm idium Triasina Vidalina?

Nodosariacea Astacolus

+

*

,

9

+

+

Austrocolomica

+

Darbyella

+

301

Genus Dentalina Eoguttulina Falsopalmula Frondicularia Glandulinoides Lagena Langella Lenticulina Lingulina Marginulina Nodoinvolutaria Nodosaria Pachyphloides Palmula Planularia Pseudoglandulina Pseudonodosaria Pseudotristix Rectoglandulina Vaginulina Vaginulinopsis Xintania

Zis Longl Chih Maok WuchChang Ind

Olen Anis +

Lad U.Tri

+

+

+

+

*

+ +

+

+

+

+

*

,

9

,

+ + +

+

+

+

*

+

+

*

9

+

*

+

*

+

+

+ +

+

+

+

+

+

+

Spirillinacea

Angulodiscus Aulotortus Coronipora Involutina Lamelliconus Pragsoconulus? Triadodiscus Trocholina Duostominacea

Diplotremina Duostomina Oberhauserella Variostoma

/ /

mm mm mm

ZisnZisongian, LonglmLonglinian, ChihnChihsian, Maok--Maokouan, WuchmWuchiapingian, Chang---Changhsingian, Ind--Induan, OlenmOlenekian, AnismAnisian, Lad--Ladinian (see Table 1 for the relationship between the stages used in South China and the global stages) +: existence recorded, *: existence inferred

different from the global data [4, 5]. In our database, the Middle Triassic specific extinction rates are also very high (Figure 4), but these extinctions mainly involved the rotalians (Figure 3) and most of them might be disaster forms [23] such as some species of Nodosaria and Aulotortus. Most survivors and the Triassic regenerated endothyrids went extinct in the Middle Triassic, with only one genus, Tetrataxis, extending into the Late Triassic in China.

302 100] ~

Genericextinction

~" ~ 90 8ot "N ~ ~9 ~

70 605040-

N

30

~ 2010-

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I

Longl Chih Maok Wuch Changh Ind

I

Olen

I

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I

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I

Cam

Figure 4. Origination and extinction rates of Permian and Triassic non-fusulinid foraminifera in South China Zis--Zisongian, Longl--Longlinian, Chih--Chihsian, Maok--Maokouan, Wuch-Wuchiapingian, Changh--Changhsingian, Ind--Induan, Olen--Olenekian, Anis--Anisian, Lad--Ladinian (see Table 1 for the relationship between the stages used in South China and the global stages)

5. SURVIVAL OF F O R A M I N I F E R A F R O M THE E N D - P E R M I A N MASS

EXTINCTION IN SOUTH CHINA All fusulinids finally faded out at the end of the Permian and only two genera among the Permian endothyrids survived into the Triassic in South China. The extinction of other foraminiferal groups is not so apparent at the end of the Permian in generic level, with 12 genera surviving into the Triassic in South China (Table 2). However, according to global data [4, 5], many more genera originated in the Paleozoic survived into the Mesozoic or later, but they have not yet been found or recognized in the Permian or Triassic of South China. For instance, Turritellella, Ammobaculites, Haplophragmoides, Reophax, Textularia, Trochammina, Erlandinita, Nodosinella, Cornuspira, Meandrospira, Dentalina, and Rectoglandulina were reported from the Triassic but not in the Permian of South China, while Endothyranella and Hemigordius are known from the Permian but not in the Triassic. Whether or not some of these may represent 'Elvis' forms [24] requires further study. The 13 species of survivors from the end-Changhsingian mass extinction in South China are all agglutinated ammodiscids. They are obviously Lazarus forms [25] as these survivors have hardly been observed in the Induan although very common in the Olenekian. Ten of these Lazarus forms became extinct in the Olenekian, one disappeared in the Anisian, and one extended into the Upper Triassic (Table 2). Of these 13 survivors, 11 species first occurred before or in the early Permian, therefore they could be regarded as opportunistic [2]. At the generic level, all survivors of agglutinated textularians are ammodiscids (4 genera) from the Permian. No Permian lituolids persisted into the Triassic, but some new lituolid genera emerged during this time. The prevalent Permian endothyrids had only two genera

303 surviving into the Triassic. In the porcelaneous miliolinids only one genus, Agathammina, has been reported from both Permian and Triassic in South China. Two genera of the perforate nodosarians, Nodosaria and Frondicularia, had also strode across the Permian-Triassic boundary. The other three nodosarian genera originated in the Changhsingian also ranged into the Triassic and developed further in the Middle and Late Mesozoic.

6. RECOVERY OF TRIASSIC FORAMINIFERA IN SOUTH CHINA So far the reports on the Early and Middle Triassic foraminifera are still very few. We have studied the Triassic for many years in South China and paid much attention to the collection of the foraminiferal fossils. Despite the effort, we have found that the frequency and abundance of Lower and Middle Triassic foraminifera in thin-sections are far less than those of the Permian. In South China, the only reports of Induan foraminifera were Ammodiscus spp. from Jiangyou, Sichuan [26] and Glomospira sp. from Laiyang, Hunan [27]. When describing the Meishan section, Changxing of Zhejiang Province, Zhao and others [28] listed three foraminiferal genera: Geinitzina, Nodosaria and Pseudoglandulina from the horizons corresponding to Bed 27 of the "standard section" [ 11]. But according to the current position of the Permian-Triassic boundary which is between 27b and 27c in the middle of Bed 27 based on the first occurrence of conodont Hindeodus parvus [29], we do not know if these foraminifers belong to Permian or Triassic. It was not until the later Early Triassic (Olenekian) that foraminifera became richer again in carbonate rocks. He [30] first recognized very abundant foraminiferal assemblages in the Jialingjiang Limestone (Olenekian) of eastern Sichuan. Since then, several other Lower Triassic foraminiferal faunas have been reported from Sichuan, Hubei, Anhui, and Jiangsu Provinces [27, 31 ]. In general, the Early Triassic foraminiferal assemblages are monotonous (composed mainly of Paleozoic types and some disaster forms, and dominated by ammodiscids), and their abundance was usually also very low. On the other hand, these foraminifers are mostly eurytopic with simplified morphologic structure, and inhabited normal marine environments. Among the nodosarian genera which first occurred in the latest Permian, the emergence of spirillinid Aulotortus marks the onset of the Mesozoic foraminiferal development. Although this genus could be regarded as a representative of Early Triassic opportunistics, it may also be the progenitor of the highly diversified Mesozoic perforate Rotaliina. The Middle Triassic saw a rapid diversification of foraminifera, signaling the onset of a biotic recovery (Figures 4, 5). Although the main part of the Yangtze Platform was being uplifted during the Indosinian Orogeny [32], reducing habitats of foraminifera in the eastern part of the platform, foraminifera nevertheless became diversified in marginal areas of the platform such as Guangxi-Guizhou, where abundant foraminiferal faunas have been found in a variety of carbonate facies (reef or shallow bank facies) [33-36]. This diversification probably indicates that the foraminifera had been successfully adapted to various new ecological conditions and, as a result, became an important component in the new ecosystem. Characteristic of the recovery stage is the occurrence of many new genera and species in nearly all groups of foraminifera, including even new genera of the predominantly Paleozoictype endothyrids (e.g. Krikoumbilica, Quasipadangia; see Table 2). Of course the most important development is in the hyaline, perforate Rotaliina, which, following the occurrence

304 25

m

20

-

e~
15 o ,.Q

E 10 -

5

--

m Zis

I I

I

Olen

L o n g l Chih Maok Wuch Changh Ind

i

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i

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125 -

100

-

e~ 75-

I

I

O 50-

Z 25-

I i

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i

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Ind

DMilioliina

i i

I

! !

i

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Lad

U.Tri

[-]Total

Figure 5. Originations of Permian and Triassic non-fusulinid foraminifera in South China ZisnZisongian, Longl--Longlinian, ChihnChihsian, Maok--Maokouan, Wuch Wuchiapingian, Changh--Changhsingian, Ind--Induan, OlenmOlenekian, Anis-Anisian, LadmLadinian (see Table 1 for the relationship between the stages used in South China and the global stages)

305 of the progenitor spirillinid group in the late Early Triassic, began to diversify in the Middle Triassic (Figure 5). This is, for instance, evident in the Duostominacea which originated and also rapidly expanded at this time.

7. CONCLUSION 1. Compared with the abundance and specific number of the Permian foraminifera in South China, those of the Lower Triassic are clearly low. However, the diversity of the Middle and Late Triassic foraminifera is high and appears comparable with those of the Permian. 2. The Permian foraminifera in South China had experienced two episodes of mass extinction, respectively at the ends of Maokouan and Changhsingian. This pattern is comparable with those of several other fossil groups [37, 38]. However, it is notable that the magnitude of these extinctions occurred differentially among different foraminiferal groups: fusulinids suffered most at the end-Maokouan extinction, while the main decimation of the endothyrids occurred at the end of Changhsingian. It is thus clear that the two mass extinctions had some kinds of underlying taxonomic selectivity despite both groups are calcareous microgranular forms. Moreover, the two extinction events also differ in that the end-Maokouan extinction did not incur a significant biotic turnover, sharply contrasted by the end-Changhsingian extinction, which resulted in an entire biotic replacement. To this regard, the two Permian mass extinctions might have been two unrelated events (see also [41 ]). 3. At least 12 foraminiferal genera outlived the end-Changhsingian mass extinction in South China, but only 13 species of four agglutinated genera survived into the Triassic. Most of the inferred survivors have not been found in the Induan, some even not in the Lower Triassic. These survivors could thus be considered as Lazarus forms. The speculated "refuges" for the end-Permian mass extinction, if they indeed existed, would most likely have been located in East Asia [39]. In connection to the 'refuge' scenario, there also have been suggestionsthat some eastern Tethyan Triassic faunas may have migrated to west Tethys during the recovery stage [21, 40]. However, to date no sites that may be considered characteristic of "refuge" faunas have been reported. (We note that a scientific definition of a mass extinction-related 'refuge' or 'refuge fauna' is yet to be rigorously defined, which no doubt will have bearing on the validity of the 'refuges' scenario). It therefore seems necessary to invoke other mechanisms to explain the origin of Permian 'Lazarus' taxa found in the Triassic. 4. The saltation in biological evolution associated with the Permian/Triassic boundary is the most significant event in the history of Foraminiferida. The end-Permian mass extinctions, on the one hand, terminated the superior Paleozoic calcareous, microgranular tests of fusulinids and endothyrids, and also initiated the origin and subsequent radiation of the Mesozoic and Cenozoic hyaline, perforate forms. The other foraminiferal groups do not exhibit parallel extinction signals although they show a proportionately higher number of survivors in the interval immediately following the end-Changhsingian extinction. The recovery stage in the Triassic took nearly 10 million years (the whole Early Triassic). Although a variety of new foraminiferal genera and species appeared during the Olenekian, the onset of the recovery as characterized by Mesozoic-type foraminifera (especially rotalians) did not occur until the Anisian, with full recovery coming even later (in the Late Triassic).

306

REFERENCES

1. Jinnan Tong, Examples of mass extinction and alternation- Foraminifera. In: Zunyi Yang, Shubao Wu, Hongfu Yin et al., (eds.), Permo-Triassic Events of South China. Geological Publishing House, Beijing. 90-97 (1993). 2. R. H. MacArthur and E. O. Wilson, The Theory of Island Biogeography. Princeton University Press, Princeton, N. J., 1967. 3. A. Eisenack, Chitinoese Huellen aus Silur und Jura des Baltikums als Foraminieren. Palaeontologische Zeitschrift, 33 (1959) 90-95. 4. A.R. Loeblich Jr. and H. Tappan, Treatise on Invertebrate Paleontology, Part C. Geol. Soc. Amer. & Univ. Kansas Press, 1964. 5. A. R. Loeblich Jr. and H. Tappan, Foraminiferal Genera and Their Classification. van Nostrand Reinhold Co., New York, 1988. 6. Jinnan Tong, The ecosystem recovery after the end-Paleozoic mass extinction in South China. Earth Science, 22 (1997) 373-376 (in Chinese with English abstract). 7. Hongfu Yin, Meihua Ding, Kexin Zhang, Jinnan Tong, Fengqing Yang, Xulong Lai, The DongwuanIndosinian Ecostratigraphy of Yangtze Platform and its Marginal Areas. Science Press, Beijing, 1995 (in Chinese with English summary). 8. Jiaxing Lin, Jiayxiang Li and Quanyin Sun, The Late Paleozoic Foraminifera in South China. Science Press, Beijing, 1990 (In Chinese with English summary). 9. Yugan Jin, B. F. Glenister, G. V. Kotlyar, Jinzhang Ssheng, An operational scheme of Permian chronostratigraphy. Paleoworld, No.4 (1994) 1-14. 10. Yugan Jin, B. R. Wardlaw, B. F. Glenister, G. V. Kotlyar, Permian chronostratigraphic subdivisions. Episodes, 20 (1997) 10-15. 11. HongfuYin, Shunbao Wu, Meihua Ding, Kexin Zhang, Jinnan Tong, F.engqing Yang, Xulong Lai, The Meishan Section, candidate of the global stratotype section and point of Permian-Triassic boundary. In: Hongfu Yin (ed.), The Paleozoic-Mesozoic Boundary Candidates of Global Stratotype Section and Point of the Permian-Triassic Boundary. China University of Geosciences Press, Wuhan, 31-48 (1996). 12. Yuanqiao Peng and Jinnan Tong, Integrated study on Permian-Triassic Boundary Bed in Yangtze Platform. Earth Science, 24 (1999) 39-48 (in Chinese with English abstract). 13. Hongfu Yin and Jinnan Tong, Multidisciplinary high-resolution correlation of the Permian-Triassic boundary. Palaeogeography, Palaeoclimatology, Palaeoecology, 143 (1998) 199-212. 14. Yichun Hao, Songyu Qiu, Jiaxing Lin and Xuelu Zeng, Foraminifera. Science Press, Beijing, 1980 (in Chinese). 15. M. D. Brasier, Microfossils. George Allen & Unwin, London, 1980. 16. J. W. Valentine and E. M. Morres, Provinciality and diversity across the Permian-Triassic boundary. Canad. Soc. Petrol. Geol. Mem., No.2 (1973) 759-766. 17. E B. Wignall and A. Hallam, Griesbachian (earliest Triassic) paleoenvironmental changes in the Salt Range, Pakistan and southeast China and their bearing on the Permo-Triassic extinction. Palaeogeogr. Paleoclim. Paleoecol., 102 (1993) 215-237. 18. Jinzhang Sheng, Linxin Zhang and Jianhua Wang, Fusulinids. Science Press, Beijing, 1988 (in Chinese). 19. Jinnan Tong, Hongfu Yin and Kexin Zhang, Permian and Triassic sequence stratigraphy and sea level

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change of eastern Yangtze Platform. Journal of China University of Geosciences 10(2):161-169. 20. L. Zaninetti, Les Foraminiferes du Trias. Riv. Ital. Paleont., 82 (1976)1-258. 21. E. Kristan-Tollmann and A. Tollmann, Ueber regional Zuege der Tethys in Schichtfolge und Fauna am Beispiel der Trias zwischen Europa und Fernost, spezielle China. Oesterr. Akad. Wiss., Schriftenreihe der Erdwissenschafllichen Kommissionen, 5 (1983) 177-230. 22. S. M. Stanley and X. Yang, A double mass extinction at the end of the Paleozoic Era. Science, 266 (1994) 1340-1344. 23. E. G. Kauffmann and D. H. Erwin, Surviving mass extinctions. Goetimes, 40 (1995) 14-17. 24. D. H. Erwin and M. L. Droser, Elvis taxa. Palaios, 8 (1993) 623-624. 25. D. Jablonski, Causes and consequences of mass extinction. In: D. K. Elliot (ed.), Dynamics of Extinction. John Wiley, New York, 183-229 (1986). 26. Naiwen Wang, The Triassic foraminiferal assemblages of Sichuan. Selected Papers to Micropaleontology, Science Press, Beijing, 49-64 (1985) (in Chinese with English abstract). 27. Jiaxing Lin, Foraminifera. Biostratigraphy in Yangtze Gorges, Part 4: Triassic-Jurassic. Geological Publishing House, Beijing, 149-157 (1987) (in Chinese). 28. Jinke Zhao, Jinzhang Sheng, Zhaoqi Yao et al., The Permian and Triassic boundary in South China. Studies on the Boundaries between the Systems. Science Press, Beijing, 58-64 (1983) (in Chinese). 29. Hongfu Yin, W. C. Sweet, B. F. Glenister et al., Recommendation of the Meishan section as Global Stratotype Section and Point for basal boundary of Triassic System. Newsl. Stratigr., 34 (1996) 81-108. 30. Yan He, The Triassic foraminifers from Jialingjiang Limestone in the southern Sichuan. Acta Palentologica Sinica, 7 (1959) 387-418 (in Chinese with English abstract). 31. Yan He, The Early and Middle Triassic foraminifers in Jiangsu and Anhui. Journal of Micropaleontology, 5 (1988) 85-92 (in Chinese with English abstract). 32. Hongfu Yin and Jinnan Tong, Late Permian-Middle Triassic sea-level changes of Yangtze Platform. Journal of China University of Geosciences, 17 (1996) 101 - 104. 33. E. Kristan-Tollmann, Foraminiferen aus dem Oberanis von Leidapo bei Guiyang in Suedchina. Mitt. Oesterr. geol. Ges., 76 (1983) 289-323. 34. Yan He, The discovery of the Middle Triassic foraminifers in central and southern Guizhou. Acta Paleontologica Sinica, 23 (1984) 420-431 (in Chinese with English abstract). 35. Yan He and Lianquan Cai, The Middle Triassic foraminifers from Tiandong Depression of Baise Basin, Guangxi. Acta Paleontologica Sinica, 30 (1991) 212-230 (in Chinese with English abstract). 36. Jinnan Tong, The Middle Triassic Environstratigraphy of Central-South Guizhou, SW China. China University of Geosciences Press, Wuhan, 1997 (in Chines with English summary). 37. Yugan Jin, Pre-Lopingian benthos crisis. Comptes Rendus XXII ICC-P, 2 (1993) 269-278. 38. Shuzhong Shen and G. R. Shi, Diversity and extinction patterns of Permian Brachiopods of South China. Historical Biology, 12 (1996) 93-110. 39. D. H. Erwin, The Great Paleozoic Crisis. Columbia University Press, New York, 1993. 40. Jinnan Tong and D. H. Erwin, Middle Triassic Gastropods of Qinling, NW China. Contribution to Paleobiology, Special Publication of Smithsonian Institution (in publication). 41. G. R. Shi, Shuzhong Shen and Jinnan Tong, Two discrete, possibly unconnected, Permian marine mass extinctions. In: Hongfu Yin and Jinnan Tong (eds.), Proceedings of the International Conference on Pangea and the Paleozoic-Mesozoic Transition. China University of Geosciences Press, Wuhan, 148151 (1999).

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Persian-Triassic Evolutionof Tethys and WesternCircum-Pacific H. Yin, J.M. Dickins, G.R. Shi and J. Tong (Editors) 92000 ElsevierScienceB.V. All rightsreserved.

309

Radiolarian evolution during the Permian and Triassic transition in South and Southwest China* Qinglai FENG, Fengqing YANG, Zhenfang ZHANG, Ning ZHANG, Yongqun GAO and Zhiping WANG Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, The People's Republic of China

This article presents the results of a recent study on the radiolarian faunas spanning the Paleozoic-Mesozoic transition in South and Southwest China. Some radiolarians from the uppermost Changxingian in the area can be compared closely with their Mesozoic counterparts, including Paurinella Kozur & Mostler and Orbiculiforma Pessagno, but their exact identity with these Mesozoic forms cannot be confirmed at present because their internal structures are unknown. The Changxingian Paurinella? is thought to be the progenitor of the Triassic Oertlispongidae Kozur and Mostler and Intermediellidae Lahm. However, the evolutionary relationship between the Changxingian Orbiculiforma? and Jurassic Orbiculiforma Pessagno is poorly understood. The survivors in the Lower Triassic of the study area, consisting of at least five genera (Entactinia Foreman, Entactinosphaera Foreman, Latentifistula Nazarov and Ormiston, Follicucullus Ormiston and Babcock and Hegleria Nazarov and Ormiston) are characterized by wide adaptability to varied ecological habitats. The recovery of the Triassic radiolarian faunas in the area occurred in the early Anisian and is characterized by moderately diverse multicyrtid nassellarians with slender shells and lacking obvious constriction among segments, and by the spumellarian species with round main spines. In the middle and late Anisian, the shells of the multicyrtid nassellarians became strong and had developed constriction between segments; and the spumellarians with both round spines and three-bladed spines were also common. In addition, some possible evolutionary relationships among the Anisian radiolarians in the area are also suggested.

1. INTRODUCTION Significant progress has been advanced in recent years about the dynamics of survival and recovery in the aftermath of mass extinctions. Generally, the biotic recovery process following a major mass extinction is divisible into three stages: survival, recovery and radiation; and the survivors of a mass extinction may be grouped into ecological generalists, pre-adapted survivors, disaster species, opportunists, crisis progenitors and Lazarus species, of which the last two taxa play a important role in biotic recovery [ 1, 2].

* This work is supported by the National Natural Science Foundation of China Project, No: 49632070 and 49772122.

310

Extensive literature is available on the taxonomy and biostratigraphy of Permian and Triassic radiolarians from Europe [3, 4], North American [5, 6], Japan [7-12], northeastern Russia [13, 14], China [15-26], Thailand [27, 28] and Philippines [29]. However, only a few studies have attempted to analyze and elucidate the dynamic process of recovery and evolution of the radiolarian faunas across the Permian-Triassic transition [28, 30-32]. At present, we know little about the survivor and progenitor taxa of the Triassic radiolarian faunas, nor we do about the general patterns of the recovery and radiation of the radiolarians after the end-Permian mass extinction. This is due largely to the scarcity of the radiolarian records from the P/T boundary strata. In recent years, we have been engaged in the stratigraphic studies of deep-sea sediments and radiolarian faunas in South and Southwest China (Fig. 1). As a consequence, we have observed Mesozoic-type progenitors from the uppermost Changxingian and Paleozoic-type survivors from the Lower and Middle Triassic. In this paper we report these progenitors and survivors, and also discuss the recovery and radiation patterns of the Early and Middle Triassic radiolarians in South and Southwest China. Of particular interest among the sections we have studied is the continuous Lower and Middle Triassic section in southwest Yunnan, where abundant radiolarians have been found from siliceous rock samples. As will be discussed in detail below, this section and its radialarian faunal succession has offered important information about the recovery and evolution of Early and Middle Triassic radiolarian faunas. ~
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311 2. P R O G E N I T O R S F R O M THE LATE C H A N G X I N G I A N OF S O U T H W E S T AND SOUTH CHINA

Marine Permian-Triassic sequences are regarded as continuous in many sections in South China [33]. The uppermost Permian Changxingian varies in lithology in response to varied effects of regional basement movement, and can be subdivided into two types, namely deepwater type and shallow water type. The Changxingian of the deep-water type, the Talung Formation and its equivalent strata, was deposited in slope to basin environments of intraplatform troughs. The progenitor taxa of Mesozoic-type radiolarians have been reported from the deep-water type facies in Guangxi, Guizhou, and Sichuan provinces, Southwest China (Fig. 1, 2). In Guizhou Province, the progenitors were collected from the Upper Permian Shaiwa Group of the Sidazhai section, which is located in northwestern Houchang town, Ziyun County. The successive section of the Sidazhai Group is about 762m thick and contains abundant fossils. Its lower-middle parts are characterized by thin to medium-bedded siltstone and mudstone with interbeds of thin cherts, yielding bivalves Claraia primitriva Yin and ammonoids Qianjiangoceras multiseptatum Zhao, Liang & Zhang, both suggesting the Changxingian. The upper part consists of thick-bedded calcirudite, thin-bedded siliceous rock, and mudstone, conformably overlain by the Luolou Formation with Ophiceras sp. and Early Triassic-type Claraia. The radiolarian progenitors reported herein were obtained from the top siliceous rock of the Shaiwa group, about 2m below the P/T boundary. Therefore, the age of the radiolarian fauna corresponds to late Changxingian stage [34]. The progenitors include Orbiculiforma? Pessagno, Paurinella? Kozur & Mostler, and some possible multicyrtid Nassellaria. Four specimens possibly belonging to Paurinella Kozur & Mostler[35] each has a spherical or subspherical shell with 3 main spines. Their shells are large, consist of several layers, and have spongy meshwork with many small circular or subcircular pores of subequal size. Their spines are round in cross sections, slender, and slightly curved (Fig. 2). All these characters are very similar to those of Triassic Paurinella Kozur & Mostler, but different from the latter by the fact that the main spines are irregularly distributed on the outer surface of the shell. Six specimens assigned to Orbiculiforma? Pessagno [36] are disc-shaped in outline. Their central cavities are deeper or higher than their prominent rims, with small pentagonal pores. Their rims are narrow, with short round spines and small polygonal pores (Fig. 2). They can be compared closely with some species of Jurassic Orbiculiforma Pessagno. However, these specimens are tentatively assigned to this genus since their interior structures are unknown. Associated with the progenitors in a single sample are the distinctive radiolarian fossil Hegleria Nazarov and Ormiston and other spherical spumellarians with or without spines. The second locality containing Paurinella? Kozur & Mostler is the Matan section, Heshan County, Guangxi Province (Fig. 1). This genus was collected from the uppermost siliceous rock of the Talung Formation, conformably overlain by a tuff bed near the P/T boundary; therefore the horizon is regarded of late Changxingian age. Six specimens were found at this section; their characters are very similar to those of the same genus from the Sidazhai section (Fig. 2). The Paurinella?-bearing horizon has also yielded a few spherical spumellarians with or without spines. The third locality bearing Mesozoic-type radiolarian progenitors is the Talung Formation of the Changjianggou section, Guangyuan County, northern Sichuan. Here, the progenitor is represented only by Orbiculiforma? Pessagno [31].

312

In the above-mentioned materials, the two radiolarian genera vary in some characters, such as the distribution and shape of the main spine in Paurinella? Kozur & Mostler and the thickness of the central cavity in Orbiculiforma? Pessagno. They may be the primitive representatives of their Mesozoic counterparts. At present, we have some confidence in suggesting an evolutionary relationship between the Changxingian Paurinella? and the Anisian Paurinella (Fig. 7) due to their age proximity, but the same cannot be held for the Changxingian Orbiculiforma? and the Jurassic Orbiculiforma because the genus as yet has not been found from the Triassic.

3. SURVIVORS IN THE L O W E R TRIASSIC OF SOUTH AND S O U T H W E S T CHINA Although most of the Paleozoic radiolarians vanished at the Permian/Triassic boundary, the extinction process and intensity was somehow varied in terms of its effects to different radiolarian taxa. Not only did a few Triassic progenitor taxa emerge in the late Changxingian, some Paleozoic taxa also survived into the Triassic. For example, the Entactiniidae Riedel, the dominant radiolarian group throughout the whole Paleozoic, persisted through the Triassic and up to the Middle Jurassic [37-39]. Species of the predominant Permian genera Fullicucullus Ormiston & Babcock and Latentifistula Nazarov & Ormiston have also been found in the Triassic of the Russian Pacific Rim and Japan [11, 13, 14]. Recently, we have also obtained some Paleozoic survivors from the Lower Triassic in Southwest and South China. In the Papai section, Cangyuan County, southwestern Yunnan (Fig. 1), all of the fossil radiolarians that co-occurred with the Griesbachian molluscan fauna (namely Claraia griesbachi Bittner, C. sp., Promyalina cf. putiatiensis (Kipanisova)) are unnamed spherical entactiniids lacking spines. These radiolarians are very small, and their shells are spongy or latticed, with one or two layers [40]. In the Muyinhe section, Lancang County, southwestern Yunnan (Fig. 1), Fullicucullus? (Fig. 2) was found in the horizons from the Triassocampe dumitricai to Triassocampe deweveri Lowest-occurrence Zones (Table 1), but not below the Triassocampe dumitricai Lowest-occurrence Zone. The absence of this genus is apparently due to poor preservation. In the siliceous mudstones below the Triassocampe dumitricai Lowest-occurrence Zone, however, some spherical spumellarians, such as Entactinosphaera with two spongy shells, y

Fig. 2. The progenitors and survivors from the late Changxingian and Triassic in South and Southwest China 1-4. Orbiculiforma? Pessagno obtained from the late Changxingian at the Sidazhai section; 5-8. Paurinella? Kozur and Mostler obtained from the late Changxingian at the Matan section; 9. Paurinella? Kozur and Mostler obtained from the late Changxingian at the Sidazhai section" 10. Astrocentrus sp. obtained from the Lower Triassic at the Dahe section" 11. Latentifistula sp. obtained from the stratum below Shengia yini zone at the Muyinhe section; 12. Entactinosphaera sp. obtained from the Triassic at the Mile section; 13-14. Follicucullus? sp. obtained from the Middle Triassic at the Muyinhe section; 15. Entactinosphaera? sp. obtained from the stratum below Shengia yini zone at the Muyinhe section" 16. Eptingium sp. obtained from the Lower Triassic at the Dahe section.

314

Entactinosphaera? with six round main spines and Latentifistula with three coplanar arms (Fig. 2), were recovered. In addition, the Paleozoic survivors such as Hegleria, Entactinosphaera, Entactinia and so on, were also collected from strata bearing Early Triassic fossils in the Jiahe section, Hunan Province [25] and in the Jiangbianjie section, Mile County, southeastern Yunnan [ 19]. Approximately, at least 5 genera of Permian radiolarians so far known in South and Southwest China had survived the Permian-Triassic mass extinction. These survivors all seem to have developed wide adaptability to varied ecological habitats, as evidenced by their presence in both shallow sea limestones and pelagic cherts [21, 41-44].

4. R E C O V E R Y AND E V O L U T I O N OF MIDDLE TRIASSIC RADIOLARIANS The Mesozoic-type Early Triassic radiolarians, associated with Early Triassic Claraia spp., are known only from the Dahe section, western Sichuan Province (Fig. 1)[19]. The radiolarian fauna was poorly preserved, and with very low diversity. Two genera, Eptingium Dumitrica [45] and Astrocentrus? Kozur & Mostler [46], are identified (Fig. 2). The former has a subtriangular shell with three main spines. The shell wall has small pores of unequal size and irregular shape. The three main spines possess the same size and shape, and are short, three-bladed and straight. These characters are more primitive than similar characters of Eptingium nakasekoi Kozur & Mostler [3], the characteristic species of the first radiolarian zone of the Anisian [ 11 ]. The latter is characterized by spherical or subspherical spongy shell with very small pores, and by more than 10 round main spines. The Middle Triassic radiolarian faunas are widely distributed in South and Southwest China (including eastern Tibet, western Sichuan, southwestern Yunnan, southeastern Yunnan and southern Guizhou) (Fig. 1). Among them, the Middle Triassic radiolarian fauna from the Muyinhe Formation in southwestern Yunnan is well-preserved, with the highest diversity. Recently, the radiolarian fauna from the formation was re-examined in detail [ 16]. Over 142 samples from the section through a thickness of 1 lm (Fig. 3) were collected and treated in hydrofluoric acid. More than 77 species and subspecies are recovered (Table 1; Fig. 5, 6). Their stratigraphic ranges in the Muyinhe Formation have been worked out (Table 1), from which the evolutionary trends and possible phylogenetic relationships of some species were investigated. Four lowest-occurrence zones were established and their correlation with other radiolarian zones is given (Fig. 4). The second well-preserved Middle Triassic radiolarian fauna was collected from the Ziyun section, Guizhou Province. It consists of about 40 species, and coincides with the Triassocampe deweveri zone [25]. However, the faunas collected from Zuogong, Mile and Mengsheng are of low diversity (about 7 genera) presumably due to poor preservation, though they were also assigned to Triassocampe deweveri zone [ 19]. The radiolarians found in Shiqu and Dahe, western Sichuan (Fig. 1), are characterized by abundant Muelleritortis cochleata (Nakazawa & Nishimura) [ 19]. This fauna is thought to be late Ladinian in age in the Palaeotethys and Circum-Pacific areas [3, 11] (Table 1) and the youngest radiolarian fauna so far known in South and Southwest China. According to the well documented radiolarian fauna of the Muyinhe Formation, the early Anisian radiolarians, corresponding to the Triassocampe dumitricai Lowest-occurrence Zone, consist of moderate diverse multicyrtid nassellarians and a few species of Spumellaria (Table 1). The nassellarians, such as Triassocampe dumitricai n. sp., Striatotriassocampe bragini n.

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sp., Striatotriassocampe laeviannulata Kozur and Mostler, Striatotriassocampe nodosoannulata Kozur and Mostler, Annulotriassocampe campanilis Kozur, Shengia yini (Feng), Yeharaia sp. and so on, are characterized by having slender shells, and by lacking obvious constriction among segments. The spumellarian species, including Paroertlispongus chinensis (Feng), Paroertlispongus multispinosus Kozur and Mostler and so on, are characterized by round main spines. Although these species bear the most primitive characters of the Triassic radiolarians, it is still hard to understand why there have been no species of the diverse radiolarian fauna found in the strata below the Triassocampe dumitricai Lowest-occurrence Zone. The middle Anisian radiolarian fauna includes those from Triassocampe coronata inflata and Triassocampe coronata coronata Lowest-occurrence

316 Table 1. The stratigraphical range of the radiolarians from the Muyinhe Formation in the Muyinhe section, Lancang, southwest Yunnan Lowest-occurrence Zone

Triassocampe sulovensis Muelleritortis sp Pentaspongodiscus sp. Zamolxis? sp. Staurolonche trispinosum Neopaurinella? sp. Neopaurinella cs ladinica Pseudostylosphaera sp. 2 Paroertlispongus rarispinosus Trassistephanidium anisicum P. asymmetricuspraetetracanthus Tetrapaurinella tetrahedrica, Archaeospongoprunum s p . Hozmadia s p . Pseudos~.losphaera longispinosa Triassocampe deweveri Sontonaella? s p . Staurolonche granulosum Parasepsagon s p .

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Table l (continued) Tdu" Triassocampe dumitricai Lowest-occurrence Zone; Tel" Triassocampe coronata inflata Lowest-occurrence Zone; Tcc: Triassocampe coronata coronata Lowest-occurrence Zone; Tde:

Triassocampe deweveri Lowest-occurrence Zone; a: existence; o: absence.

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Biostratigraphy

Bragin (1991)

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Eptingium nakasekoi Parentactinia nakatsu gaw ae ns is Fullicucullus

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Figure 4 Correlation of Triassic Radiolarian biostratigraphy among Southwest Yunnan and other areas E: early; T: Triassocampe

Zones, and is characterized by many new genera with three-bladed main spines. For example, Pseudostylosphaera, Archaeospongoprunum, Astrocentrus, Muelleritortis and Ditortis, occurred for the first time, along with some genera continuing from the Triassocampe dumitricai Lowest-occurrence Zone. These new genera became the dominant members in the late Anisian and Late Triassic. Most of the species that originated in the Triassocampe dumitricai Lowest-occurrence Zone disappeared in the Triassocampe deweveri Lowest-

318

Figure 5 Some species of Family Oertlispongidae and Family Intermediellidae from the Middle Triassic at the Muyinhe section in Southwestern Yunnan l.Paroertlispongus chinensis (Feng); 2,3. Neopaurinella deweveri Feng; 4. Neopaurinella kozuri Feng; 5. Neopaurinella cf. ladinica Kozur & Mostler; 6. Paroertlispongus sp.; 7, 9. Paroertlispongus multispinosus Kozur & Mostler; 8. Paroertlispongus cf. diacanthus (Sugiyama); 10. Tetrapaurinella tetrahedrica Kozur & Mostler; 11, 12. Paurinella aequispinosa Kozur & Mostler; 13, 14. Paurinella cf. curvata Kozur & Mostler

319

Figure 6 Some nassellarians from the Middle Triassic at the Muyinhe section in Southwestern Yunnan 1.Triassocampe coronata coronata Bragin; 2, 3. Triassocampe coronata inflata Feng; 4, 5. Triassocampe dumitricai Feng; 6. Striatotriassocampe bragini Feng; 7. Striatotriassocampe laeviannulata Kozur & Mostler; 8. Striatotriassocampe nodosoannulata Kozur & Mostler; 9. Shengia goricani Feng; 10. Shengia yaoi Feng; 11. Shengia solida Feng; 12. Yeharaia japonica? Nakaseko & Nishimura; 13. Shengia y&i (Feng); 14, 15. Shengia nanpanens& Feng; 16, 17. Triassocampe relica Feng; 18. Triassocampe deweveri Nakaseko & Nishimura; 16. Triassocampe deweveri (Nakaseko & Nishimura).

320

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321

Figure 8 Possible relationships between some species of Striatotriassocampe and Triassocampe from the Middle Triassic at the Muyinhe section in Southwestern Yunnan TI: Lower Triassic; Tdu: Triassocampe dumitricai Lowest-occurrence Zone; Tci: Triassocampe coronata inflata Lowest-occurrence Zone; Tcc: Triassocampe coronata coronata Lowest-occurrence Zone

A detailed analysis of the shell morphology and a thorough investigation of the stratigraphic ranges allow us to propose four possible evolutionary trends. (1) The families Oertlispongidae Kozur and Mostler, Intermediellidae Lahm (including Paroertlispongus? multispinosus with one strong main spine, Paroertlispongus Kozur and

322

Figure 9 Possible relationships between some species of Striatotriassocampe, Shengia and Yeharaia from the Middle Triassic at the Muyinhe section in Southwestern Yunnan T l: Lower Triassic; Tdu: Triassocampe dumitricai Lowest-occurrence Zone; Tci: Triassocampe coronata inflata Lowest-occurrence Zone

Mostler with two main spines, Paurinella Kozur and Mostler with three main spines, Tetrapaurinella Kozur and Mostler with four main spines) and Intermediellidae gen. and sp.

323

Figure l0 Possible relationships between some species of Eptingium from the Lower and Middle Triassic in Southwest China T l: Lower Triassic; Tdu: Triassocampe dumitricai Lowest-occurrence Zone; Tci: Triassocampe coronata inflata Lowest-occurrence Zone; Tcc: Triassocampe coronata coronata Lowestoccurrence Zone; Tde: Triassocampe deweveri Lowest-occurrence Zone

indet, with five main spines seem to have evolved directly from the Changxingian Paurinella? sp. Paroertlispongus chinensis seems to be the ascendant of Neopaurinella Kozur and Mostler (via the former developing by-spine to become the third spine). In the Oertlispongidae Kozur and Mostler and Intermediellidae Lahm, the changing trend of the shells during the Anisian is characterized by having their straight main spine becoming curved (Fig. 7). (2) Striatotriassocampe bragini gave rise to the lineage Triassocampe dumitricaiTriassocampe coronata inflata-Triassocampe coronata coronata, characterized by a

324

progressive increase of the shell width and a progressive development of the circumferential ridge in each abdomen segment (Fig. 8). (3) Shengia seems to have evolved from Striatotriasscompe by gradually increasing the shell width and the constrictions between segments. Striatotriassocampe bragini gave rise to the evolutionary lineage Shengia goricani-Shengia yaoi-Shengia solida, characterized by gradually increasing width of the thorax segment and by developing elliptical pores to subcircular pores. S. solida seems to be the ascendant of Yeharaia Nakaseko and Nishimura by the development of an apical horn in the latter genus (Fig. 9). (4) The trends of the shell changes in Eptingium Dumitrica from Early Triassic to Anisian are as follows: the main spines change from short to long, slender to strong; the grooves on the main spines change from narrow to wide; and the pores of the shell change from small to large, and from irregular to subcircular (Fig. 10).

ACKNOWLEGEMENTS

Drs. H.-R. Wu, N.-W. Wang, Q. Yang and Y.-J. Wang are cordially thanked for discussion on radiolarian identifications. We wish to express our sincere thanks to Profs. H.-F. Yin and W.-C. Xia for valuable advice and encouragement. Our thank are also extended to Profs. G.R. Shi, X.-L. Lai and J.-N. Tong for their critical review of the manuscript. Special thanks are due to Miss S.-X. Zhang for taking care of SEM photographing, and to Mr. B. Chen for his assistance in plate preparation.

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Persian-Triassic Evolutionof Tethys and WesternCircum-Pacific H. Yin, J.M. Dickins, G.R. Shi and J. Tong(Editors) 92000ElsevierScienceB.V. All rightsreserved.

327

Asian-western Pacific Permian Brachiopoda in space and time: biogeography and extinction patterns G.R. SHI and Shuzhong SHEN School of Ecology and Environment, Deakin University, Rusden Campus, 662 Blackburn Road, Clayton, Victoria 3168, Australia

A database of 86 Permian brachiopod families, 411 genera and 1931 species of the Asianwestern Pacific region was analysed using a range of statistical measures to unravel the changing patterns of diversity, origination and extinction rates through six Permian intervals. Prior to the quantitative analysis, the evolutionary pattern of the Permian marine provincialism of the region was reviewed to provide a framework for investigating possible palaeogeographical patterns of the Permian brachiopod extinctions and the likelihood of biogeographical control on the extinctions. It was revealed that the Permian brachiopod diversity variation and extinction patterns are broadly compatible among the Gondwanan, Palaeo-equatorial and Boreal Realms as well as with the overall diversity and extinction pattern of the Asian-western Pacific region. Two major extinctions are recognised regardless of taxonomic ranks (species, genera, or families): one occurring during the Kazanian-Midian (end-Guadalupian) and the other at the Changhsingian. The end-Guadalupian extinction is most pronounced in the Gondwanan and Boreal Realms and less well expressed in the Palaeoequatorial Realm. On a regional scale, the end-Guadalupian extinction appears to have lasted through the whole Kazanian-Midian interval. The Changhsingian extinction is recorded only in the Palaeo-equatorial and Gondwanan Realms. This event appears to be much more severe than the end-Guadalupian extinction and also lasted a much shorter duration than the latter event. The two major extinction episodes were coupled with low originations. Comparatively high originations occurred in the Sterlitamakian-Aktastinian (middle Early Permian) and Wuchiapingian (early Late Permian). It was also revealed that there appears to be a positive correlation between provinciality and species and generic diversity, but no direct, consistent correlation between Permian palaeolatitude and brachiopod species diversity in the Asian-western Pacific region. Discussion on the causes of Permian extinctions was not intended. However, we found that there is a good correlation in timing between the end-Guadalupian extinction and at least a regional (Asian-western Pacific wise) regression. The relationship between eustatic motion and the Changhsingian extinction is far less clear. Although an end-Changhsingian transgression appears evident in view of our field observations of several sections in South China, the exact timing of this event in relation to the timing of the Changhsingian extinction requires further study.

328 1. INTRODUCTION The end-Permian mass extinction is a widely perceived global bioevent; it brought to an end of the Palaeozoic Era and also, probably, initiated one of the most extensive evolutionary radiations in the Phanerozoic. It has been estimated that this mass extinction had eliminated about 49% of marine families, some 78-84% of marine genera and up to 96% of marine species [1]. As such, the magnitude of the end-Permian extinction event is considered by many to be more significant than the Cretaceous-Tertiary extinction. The end-Permian extinction as a significant geological event has now been widely recognised, but details over its timing, duration and relationships with contemporary marine provincialism and pre end-Permian extinction events remain unclear. For instance, we do not know whether the Permian suffered one single major extinction at the end of the period (a widely held view, see, e.g. [2]) or a multiple of prior extinctions that led to the final endPermian mass extinction [3-5]. Also little known is about the role, if any, of marine provincialism in regulating the diversity and extinction patterns. Currently, there exist two principal views on the geographical pattern of the Permian extinction, with one arguing for a single uniform extinction (in the sense of both timing and extinction intensity) across the entire globe at the end of the Permian [6], and the other in favour of a geographically and temporally differential extinction process and pattern between continental Pangea (Eurasia and Gondwana) and the island terranes in eastern Tethys (South China, in particular). In advocating the latter view, Erwin [1 ] suggested a two-phase Late Permian extinction event. According to this scenario, the first, longer, phase occurred at the close of the Guadalupian and was mainly confined to continental Pangea, excluding isolated islands such as South China and Indo-China in the eastern Tethys. These island terranes, presumably due to their isolated situation, may have acted as a major refuge for many surviving marine invertebrate taxa during this first phase of extinction. Erwin's second phase of the Late Permian extinction began several millions years later and was largely restricted to South China and adjacent Cathaysian islands. It is clear from Erwin's interpretation that geographical isolation of major continental blocks and marine provincialism had a significant impact on the geographical and temporal patterns of Permian extinction(s). Researchers working on other extinction periods of the geological record (e.g. [7-8]) have also expressed similar views. The purpose of this paper is to examine the palaeogeographical pattern of the end-Permian extinctions based on the Permian Brachiopoda data from the Asian-western Pacific region. Specific questions that we attempt to investigate are (1) what are the overall diversity change and extinction patterns of brachiopod species, genera and families in the Asian-western Pacific region through the Permian? (2) what are the diversity change and extinction patterns of Permian Brachiopoda in each biogeographical realm through the Permian? and (3) whether or not the mode of the Permian extinctions for the whole Asian-western Pacific region is compatible among the realms? Answers to these questions will have significant implications as to the cause or causes of the end-Permian mass extinctions. For instance, if the timing and magnitude of extinctions are different among the different biogeographical realms, it would suggest that the extinctions occurred in different realms at different times and hence most likely to have been caused by different mechanisms. On the other hand, if the mode of extinction were compatible among all contemporary realms, at least a regionally uniform extinction generator would be implied.

329 2. DATA, METHODOLOGY AND TERMINOLOGY For the purpose of this paper, the Asian-western Pacific region refers to the Siberian Platform, East and Southeast Asia, India, Australia and New Zealand (Fig. 1). This region is chosen for the purpose of this paper because it stretched almost 180 degree palaeo-latitude from south to north during the Permian and, as such, embraced all the three major Permian marine biogeographical realms, namely the northern temperate to subpolar Boreal Realm, the southern temperate to subpolar Gondwanan Realm, and the intervening Palaeo-equatorial Realm [9-12]. Another significant feature of this region was its evolving palaeogeographical configuration and marine provincialism during the Permian: it accommodated a cluster of moving continental terranes, notably South China, North China, Indo-China, the Tarim Basin, the Shan-Thai terrane, and the North Qiangtang block. These terranes, according to many reconstruction maps [13-15], all appear to have been advancing in a northerly direction although seemingly at different velocities with respect to each other and to continental Pangea. The Permian brachiopod database of this region consists of 86 families, 411 genera and 1931 species from six time intervals of the Permian Period [ 16]. The database was extracted from a multi-volume compendium of the Asian-western Pacific Permian brachiopod faunas already compiled and published (see [16] and references therein provided). The extensive database contains detailed information on the spatio-temporal distributions of Permian brachiopod species, genera and families in the Asian-western Pacific region, therefore providing an ideal data source for the purpose of this paper. For the compilation, the Asianwestern Pacific region has been divided into a number of distinct tectonic entities (Fig. 1). These could be fold belts, terranes, epicontinental basins, or relatively large continental blocks (e.g., the Siberia block). In the database, these entities were treated as individual operational geographical units (OGUs). Each OGU may be a single fossil locality or a group of contemporaneous fossil localities from the same tectonic entity. As we attempt to address in this paper the diversity and extinction issues within the framework of Permian marine biogeography, we believe that the OGU-based sampling approach is appropriate for identifying genuine biogeographical entities believed to be free of the influence of ecological factors. The database consists of three separate data sets representing three taxonomic ranks: species, genus and family. The division of the database into different taxonomic ranks is necessary to investigate how the magnitude and mode of extinctions are expressed by different taxonomic ranks. In compiling the database, we have evaluated all the available published Permian brachiopod literature of the region and, wherever necessary and possible, have revised the taxonomy and age determinations of the published records in accordance with the current practice of brachiopod taxonomy and the Permian chronostratigraphical scale adopted herein (see discussion below). Using the same database we have carried out a sequence of stage-bystage quantitative analyses of the Permian brachiopod provincialism of the Asian-western Pacific region, from which a detailed marine biogeographical framework can now be established (see below). The employment of the same data set for both biogeographical and extinction analyses ensures the consistency of taxonomy and biostratigraphical correlation, thus adding a strong degree of robustness to the analytical results and interpretation.

330

Figure 1. The Asian-western Pacific region referred to in this paper and its main Late Palaeozoic tectonostratigraphic units (cratons or fold belts). The inset shows the study area (shaded) in a reconstructed Late Permian global palaeogeographic map (Ziegler et al. [15]).

331

In accordance with the Permian timescale originally adopted for the compilation of the database, we herein also use the combined Uralian and Tethyan scheme in a three-fold Permian System framework (Table 1). Alternatively, one could have followed Permian chronostratigraphical scale of Jin et al. [17], but this practice would impose a degree of inconsistency with the original database. Nevertheless, because the scale employed here is broadly correlatable at stage level with that of Jin et al. (Table 1), it is unlikely that the usage of the latter scale would alter the diversity and extinction patterns recognised in this paper. The six Permian time intervals analysed in this paper are also shown in Table 1. As shown, we have not followed the formal stage boundaries precisely; thus the Late Asselian is grouped Table 1. Permian timescale and stage durations (note variation between two schemes. The shaded areas are the six Permian intervals referred to in this study).

C hro nostratigrap hy Scale used herein Changhsingian

Geoch ro nology

Jin et al. [171

Young and LaurieI221 Menning and Jin [231 251 Ma

= Changh"gt singian

4 Mys , 2 5 5 Ma

Wuchiapingian

~

Wuchiapingian

Midian

~ Capitanian

|

4.5 Mys [

4 Mys

7.5 Mys

4 Mys

4 Mys

' 259 Ma 9 j,,,q

om .

.

.

.

.

263 Ma

.

Kazanian

,~

Wordian

J

4 Mys

5 Mys

267 Ma

oil

Ufimian

2 Mys

Roadian

3 Mys 270 Ma

Kungurian

Kungurian '='

4 Mys

3 Mys

'274 Ma

,m

E

on,,q

Artinskian "

Artinskian

11 Mys

6 Mys

285Ma

o~,,q m

Sakmarian

Sakmarian

8 Mys

7 Mys

293 Ma Asselian

Asselian

5 Mys 298 Ma

6 Mvs

332

with Early Sakmarian, so are Late Sakmarian with Early Artinskian and Late Artinskian with Early Kungurian. This approach was proven necessary in the early stage of our compilation of the database because the age of some of the brachiopod faunas appear to span across stage boundaries. A good example of this case is the large brachiopod fauna of the Rat Buri Limestone of southern and western Thailand. The exact age of the various brachiopod assemblages from the isolated limestone hills remains contentious although it was regarded to be Artinskian by Grant [18] and Early Kungurian by Waterhouse [19], or even younger as noted by Angiolini [20]. In our treatment for the purpose of this study, we include the Rat Buri brachiopod faunas as a whole in the Late Artinskian-Early Kungurian interval, implying that this fauna could be either Late Artinskian or Early Kungurian or Late Artinskian to Early Kungurian in age. Despite all attempts to make the database as taxonomically and biostratigraphically sound as possible, the particular quality and hence reliability of the database must be balanced against the shortcomings of this and other such compilations. First, the age control of the individual faunas may vary from the age accepted in the database although this is unlikely to have caused any significant impact on the statistical results because the six Permian time intervals investigated were delineated in such a way that the majority of the brachiopod faunas in the database could be assigned to a specific time interval with good confidence. Secondly, the revised taxonomic listing of each individual brachiopod fauna obviously reflects our understanding of the taxa concerned, which may of course vary from that of other workers. The potential effect of this practice on the statistical analysis, however, is minimal because internal taxonomic consistency is maintained by the fact that the taxonomic revision was all carried out by us. In addition, the completeness of each faunal list is subject to the degree to which the fauna has been sampled and studied. It is therefore necessary to filter the data with a statistical measure as a basis for data selection. For this purpose, we have employed the quantitative index of Sampling Efficiency (SE) as originally proposed by Stehli and Grant [53] and revised by Shi and Archbold [54]. As a result, samples with very low SE values were excluded from the statistical analysis. These are usually brachiopod assemblages which have either not been systematically described and/or illustrated, rendering their taxonomic composition impossible to estimate. We believe that the database constructed in the above manner is the most complete and comprehensive data source of its kind currently available. With the exception of the Ufimian and late Kungurian, all the other stages of the Permian have been covered by the analysis (see Table 1). We have deliberately left the Ufimian stage out because of its limited international correlation potential as it is currently defined and understood. The stratotype of the Ufimian is a highly localised lithofacies characterised mainly by non-marine grey clastic sediments and red beds with abundant intercalations of dolomite and gypsum, and few marine fossils [21 ]. Therefore, we have found it extremely difficult to assign brachiopod faunas to this stage by brachiopods alone. In this regard, the Roadian, which is equated with the Ufimian in Jin's et al scale (see Table 1), could have been used. However, the Roadian brachiopod faunas of the southwest USA are highly endemic on a global scale and hence of limited value as a correlation tool to the Asian-western Pacific region. Nevertheless, considering that the Ufimian is represented by only 3 Mys [22] and the Roadian by only 2 Mys [23] (Table 1), we believe that the exclusion of the Ufimian/Roadian data from this study should not jeopardise or mislead the recognition of the overall patterns of the Permian brachiopod biogeographic and diversity patterns.

333

T a b l e 2. F o r m u l a e a n d n o t a t i o n o f diversity, extinction and o r i g i n a t i o n rates. Measures

%--4

4-.a 9,-,~ r~'-~

Formula

Explanation

raw diversity

Ti

Total number of taxa of interval i.

standing diversity 1

SDv 1= Ti-Ei/2-Oi/2

Estimate of standing diversity at midpoint of the time interval. This measures does not take into account taxa confined to the time interval.

standing diversity 2

SDv2 = SDv l +Ci/2

This measure differsfi'om SDvl by taking into account the taxa confined to the time interval based on the assumption there is a 50~ chance that any one of the Ci taxa were present at the midpoint of the interval.

extinction rate 1

ERI=(Ei)/(Ti)

The proportion of extinctions recorded in a time interval divided by the total number of taxa recorded in the interval.

extinction rate 2

ER2=(Ei-Ci) /(Ti-Ci)

In extinction rate 2 taxa confined to the interval are not counted.

:This measure equals to the weighted average of the proportion of taxa present at the beginning (~f a time interval that become extinct during the interval; and SER=I/2[(Ei-Ci) the ratio of the number of taxa that become extinct in /SDv 1] the interval to the number of taxa present at the end of the time interval. The taxa confined to the interval are not counted.

.4..a I-~

standing extinction rate

origination rate 1

ORl=(Oi)/(Ti)

origination rate 2

OR2=(Oi-Ci) /(Ti-Ci)

The proportion of originations recorded in a time interval divided by the total number of taxa recorded in the interval.

o ra~

.~r

~

m

standing origination rate

! In origination rate 2 taxa confined to the interval are not counted. m

SOR=I/2[(OiCi)/SDV1]

|

i This measure equals to the proportion of taxa present at the end of a time interval that originated during the interval. Taxa confined to a time interval are n o t counted. T

Ci =total number of taxa confined to interval i; Ei =total number of taxa extinct in interval i; Oi =total number of taxa originating in interval i. In o r d e r to e x a m i n e the t e m p o r a l v a r i a t i o n s o f b r a c h i o p o d d i v e r s i t y a n d i d e n t i f y p o s s i b l e e x t i n c t i o n points, w e h a v e u s e d a n u m b e r o f statistical m e a s u r e s , l a r g e l y f o l l o w i n g H a r p e r [24]. T h e s e m e a s u r e s are s h o w n a n d e x p l a i n e d in T a b l e 2. D i v e r s i t y a n d e x t i n c t i o n m e a s u r e s are d i v e r s e in the literature a n d p o t e n t i a l l y c a n l e a d to c o n f l i c t i n g r e s u l t s e v e n a p p l i e d to the s a m e data. In o u r study, the d i v e r s i t y or e x t i n c t i o n rates o f an i n t e r v a l are m e a s u r e d p r i n c i p a l l y b y the n u m b e r o f t a x a p r e s e n t or e x t i n c t at the m i d d l e p o i n t o f the i n t e r v a l in p r o p o r t i o n to the r a w or w e i g h t e d total n u m b e r o f t a x a o f the s a m e i n t e r v a l (see T a b l e 2 for m o r e details o f e a c h f o r m u l a ) . W e h a v e not s t a n d a r d i s e d t h e s e rates b y the t i m e d u r a t i o n o f e a c h interval b e c a u s e the t i m e d u r a t i o n o f the P e r m i a n s t a g e s r e m a i n s u n f i x e d a n d v a r y g r e a t l y a m o n g d i f f e r e n t s c h e m e s o f c a l i b r a t i o n (see T a b l e 1 for c o m p a r i s o n o f t w o a l t e r n a t i v e schemes).

334

In order to calculate the diversity, origination and extinction rates in the AsselianTastubian and Changhsingian intervals, the presence/absence data of the various Permian brachiopod species from the pre-Asselian and post-Changhsingian stages were also considered and calculated. Similarly, the diversity of the Permian holdover species and genera in the earliest Triassic Griesbachian was also calculated, but its origination and extinction rates were not considered. This is because only a few Permian-like brachiopods are present in this stage and all of them became extinct by the end of the Griesbachian, therefore giving an unmeaningful impression of 100% extinction and nil origination.

3. F R A M E W O R K OF PERMIAN MARINE BIOGEOGRAPHY

Recent reviews of the global Permian marine biogeography have been provided by Shi et al. [25], Jin and Shang [26] and Grunt and Shi [12] and will not be repeated here. The framework of the dynamic Permian marine provincialism of the Asian-western Pacific region can be summarised from the sequence of detailed quantitative studies of Permian Brachiopoda carried out by Shi and colleagues [27-30, 31-33] (Fig. 2). 3.1. Evolutionary pattern of the marine provincialism In general, three broad biogeographical realms appear to have persisted throughout the Permian in the region. The Boreal Realm is largely confined to the Arctic region and characterised by a comparatively low diversity and limited occurrences of fusulinacean foraminifera and compound rugose corals. The floras of this realm are dominated by cool to cold temperate biomes [34]. The Permian Gondwanan Realm is conventionally regarded as being composed of Australia, New Zealand, South America, southern Africa, Peninsula India, and much of the Himalaya. This realm is well known for its low diversity, lack (except for a few isolated localities) of fusulinaceans and compound rugose corals, and the presence of a distinct association of endemic genera and cool temperate to glacial plant biomes. The Palaeoequatorial Realm [12] is typified by diverse fusulinaceans, compound rugose corals and tropical plant biomes. This realm extends from Japan in eastern Asia westwards through central Asia to the Mediterranean region, and is also recognised in southwest United States, Mexico, Central America, and northern South America. On a global scale, the core constituents and principal characteristics of these realms appear to have been well defined. However, as depicted in Fig. 2, the spatial position and palaeogeographical configuration of each realm with respect to palaeolatitude varied significantly through the Permian. This variation appears to have initiated major changes in the composition of faunas over time as well as in the composition of the palaeogeographical members of each realm. During the Asselian-Tastubian interval (Fig. 2A), the Gondwanan Realm is represented by the Indoralian and Himalayan Provinces and incorporated all northern peri-Gondwanan terranes such as the Shan-Thai terrane, Lhasa terrane and southeast Pamir. The Palaeo-equatorial Realm in the Asian-western Pacific region was represented by the Cathasyian Province, consisting of Asselian-Tastubian faunas of South China (possibly with parts of Japan attached), North China (also possibly with parts of Japan attached), IndoChina and North Qiangtang blocks. In the meantime, the Boreal Realm was represented by the Verkolyma Province restricted to northeast Siberia and northern Mongolia. During the subsequent 'mid-Permian' (Late Sakmarian to Midian; note that our usage of 'mid-Permian' is different from that of Dickins et al. [55] and Dickins [56]) intervals, the

335

Figure 2. Evolution of Permian brachiopod provincialism of the Asian-western Pacific region (see Fig. 1 for names of eastern Tethyan tectonic blocks) (base map from Ziegler et al. [15]).

336 Asian-western Pacific region displayed a highly dynamic and varied biogeographical pattern [25] (Fig. 2B). Two main features may be noted. Firstly, the Asselian-Early Sakmarian Indoralian Province had evolved into two separate provinces: Austrazean Province incorporating New Zealand and eastern Australia, and Westralian Province embracing the Western Australian epicontinental basins and some northern peri-Gondwanan terranes. Secondly, two distinct transitional provinces developed and ended within this broad interval: the Sibumasu Province in the south and the Sino-Mongolian Province in the north [25]. The Sibumasu Province as a transitional biogeographical entity became recognisable as early as in the Late Sakmarian and progressively strengthened through the Kungurian to the Kazanian, then vanished by the end of the Middle Permian (Midian or Capitanian). Throughout its history, the transitional Sibumasu faunas were characterised by an admixture of Gondwanan and Cathaysian elements in addition to wide-ranging and endemic taxa. The level of mixture varied over time and tended to have been dominated by stronger Gondwanan elements in the early stage then by more Cathaysian taxa in the later stage [33]. A number of factors are required to fully understand the dynamic nature of the Permian biogeographical signature of the Sibumasu Province. Shi and Archbold [33] preferred an integrated model, combining the scenarios of tectonic vicariance and climatic amelioration. In this integrated solution, the warming effect demonstrated by the northward drift of the Shan-Thai terrane is understood to have been superimposed and hence enhanced by the contemporary post-Late Sakmarian warming. Abrupt climatic amelioration accompanied by rapid expansion of the palaeotropical zone across the Early and Late Sakmarian boundary may have been primarily responsible for the marked change of provinciality in both eastern Gondwana and the ShanThai terrane. Subsequent, more gradational, changes in the marine provinciality of the ShanThai terrane may be explained by the continuing northward drift of the Shan-Thai terrane (possibly superimposed by a comparatively slower northward drifting of the entire Pangea), accompanied by more gradual warming, shrinking of the palaeo-polar to palaeo-temperate climatic zones and southward expansion of the palaeo-tropical belt. As the Shan-Thai terrane was approaching Cathaysia and its climatic conditions ameliorated further, its cool-wateradapted Gondwanan taxa were eliminated and replaced progressively by more Cathaysian taxa. By the Late Permian (Wuchiapingian and Changhsingian) (Fig. 2C), the Shan-Thai terrane may have drifted to the vicinity of the Cathaysian massifs and, as a result, became firmly occupied by warm palaeo-tropical conditions and faunas, resulting in the final demise of the Sibumasu Province and its incorporation into the Cathaysian Province. The evolution of the Sino-Mongolian Province is complex due to its palaeogeographical and tectonic position and seaway connections to the Palaeo-equatorial Cathaysian sea in the south and southeast and to the Arctic sea to the north (Fig. 2B). This unique tectonopalaeogeographical position, coupled with contemporaneous global climatic and eustatic changes, facilitated the transition of northeast China and adjacent regions from a middle Early Permian (Sakmarian-Artinskian) dual provinciality (both Boreal and Cathaysian provinces present) to a mixed fauna and floral stage in the Middle and Late Permian [35, 52]. During the early Early Permian (Asselian), this region was dominated by warm-water Cathaysian faunas, reflecting its biogeographic isolation from the Arctic sea. Succeeding this Cathaysian warmwater faunal stage, two distinct marine faunas developed within the broad Sino-Mongolian seaway: one, characteristic of the Boreal fauna, prevailed north of the Juyan-Solon-Xar Moron River suture; the other, a predominantly Cathaysian warm-water fauna, dominated in the south on the northern margin of the North China block. The presence of this dual provinciality in the Sino-Mongolian seaway during the Sakmarian-Early Artinskian implies

337 significant palaeogeographical and/or climatic separation between the northern and southern shores of the Sino-Mongolian seaway. Wang and Fan [36] have recently recognised Middle Permian radiolarians from several ophiolite outcrops along the Juyan-Solon-Xar Moron River suture in northeastern Inner Mongolia, testifying to persistent oceanic conditions between North China and Siberia during the Middle Permian. The provinciality of the Sino-Mongolian seaway had a major turn at the beginning of the Late Artinskian (Baigendzhinian) when a distinct mixed, interpretedly mesothermal, marine fauna emerged within the seaway, intermingling both Boreal and Cathaysian elements. This faunal integration has been interpreted to indicate climatic amelioration as well as the downsizing of the Sino-Mongolian seaway caused by the terminal collision of North China with Siberia and associated regional tectonic uplift. The presence of an exclusive Cathaysian marine fauna during the Early Guadalupian indicates a return to the dominance of warm-water Cathaysian currents into the Sino-Mongolian seaway. Marine sedimentation ceased towards the end of the Guadalupian, signalling the final uplift of the area above the sea level. Late Permian continental deposits of the Great Tianshan-Mongol-Hinggan Fold Belt contain distinctive mixed Cathaysian and Angaran flora [37], indicating free migration of flora between Siberia and North China and hence the completion of continental suturing between these two largest tectonic blocks in northeast Asia.

4. PALAEOGEOGRAPHICAL PATTERNS OF DIVERSITY, EXTINCTION AND ORIGINATION 4.1. The A s i a n - w e s t e r n Pacific region as a w h o l e

Several features of diversity variation of the Permian Brachiopoda across the whole Asianwestern Pacific region may be noted and will provide a background for comparison with the diversity and extinction patterns of the realms (see below). Firstly, we note the diversity, extinction and origination patterns. The diversity histograms of the Permian brachiopod families, genera and species of the Asian-western Pacific region (Fig. 3A) exhibit two major diversity drops: one occurring at the Kazanian-Midian (or end-Guadalupian), the other marked at the end of Changhsingian. As might be expected, the diversity drops are most strongly expressed by the species data and less well reflected in the familial data. From the Baigendzhinian-Early Kungurian to the Kazanian-Midian, the species diversity dropped from 580 to 384, genera from 200 to 136, and families from 71 to 59. In comparison, the Changhsingian diversity drop is markedly higher, with 94% species, 85% genera and 76% families becoming extinct across the Permian-Triassic boundary. The two distinct diversity drops can also be discerned from the plots of standing extinction rates (Fig. 4). The values of origination rate across the six Permian intervals of the Asian-western Pacific region is also of note (Fig. 4C). The profiles of both generic and specific standing origination rates are characterised by two distinct spikes: one appearing at the Sterlitamakian-Aktastinian, the other at the Wuchiapingian. The first of these origination spikes is interesting because it does not seem to succeed any recognisable major extinction event. The Wuchiapingian origination event, on the other hand, is preceded by the end-Guadalupian diversity drop. The origination succeeding the Changhsingian extinction is not analysed in this work but according to the diversity of brachiopods found in the Griesbachian (Fig. 3A) it appears to be very low.

338

A

Asian-West Pacific region (general data) 0.

families

n o.

::: ,

genera

220 200 180 160 140 120 1000 60 40 20 0

70 6O 50 4O 30 20 10 f)

n o.

species

600 '~:.

::

500 40O 3OO 200 100 0

A-T S-A B-EKK-M Wu CX Gr

A-T S-A B-EKK-M Wu (N

B

Gr

A-T S-A B-EKK-M Wu Ck

Gr

Boreal Realm n o.

families

n O.

genera

n o. 250

50 40

~i?,

30

"

~

200

~~

~'.--

150

,

20

100

10

50

0

A - T S - A B - E K K - M W u Ck

Gr

A-TS-AB-EKK-MWu

C

species

Ck

0

Gr

A - T S - A B - E K K - M W u Ck

Gr

Palaeoequatorial Realm no. 50

families

no. 100

40

80

30

60

20

40

10

20

0

genera

O o. 35 300 250 200

(k

~-

150 100 50

0 A-T S-AB-EKK-MWu

species

0

Gr

A-T S-AB-EKK-MWu

C~

Gr

A-T S-AB-EKK-MWu

(N

Gr

Gondwanan Realm

D no. 60

families

no.

50 40 3O 20

160

genera

no. 350

140 120 100

300 250 200

species

150 60 40 20

10

100 50

0

0 A-T S-AB-EKK-MWu

Ck Gr

A-T S-AB-EKK-MWu

Ck

Gr

A-T S-AB-EKK-MWu ( k

Gr

Figure 3. Changing patterns of Permian brachiopod species, generic and familial diversities in the whole Asian-western Pacific region, as well as in the Boreal, Palaeo-equatorial and Gondwanan Realms through the Permian. Notes areas of major diversity chops (arrowed).

339

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Figure 4. Changing patterns of standing diversity (A), extinction rates (B) and origination rates (C) of Permian brachiopod species and genera of the Asian-western Pacific region through the Permian.

340 Secondly, we draw attention to the relationships of diversity with respect to provinciality and palaeolatitude gradient. A plot of the provinciality (number of biotic provinces) against species and generic diversity through the six Permian intervals (Fig. 5) demonstrates a broad

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Figure 5. Relationships between brachiopod species and generic diversity and marine provinciality (number of provinces) through the Permian. positive correlation between provinciality and diversity. Both the species and generic diversity peaked at the Baigendzhinian-Early Kungurian interval when the provinciality also reached its highest point (6 provinces). This interval correlates well with the development of two distinct transitional faunal zones in Asia discussed by Shi et al. [25]. Similarly, the points of the two diversity drops, respectively at the Kazanian-Midian and the Changhsingian intervals, are well matched by periods of low provinciality. There is a widely accepted notion that species richness correlates inversely with latitude settings: that is, higher diversity is expected at lower latitude zones and lower diversity occurs at higher latitudes. To test this scenario with the Permian brachiopod data set, we have compiled a data matrix of species diversity of well-dated Permian brachiopod faunas from a number of key operational geographical units (OGUs) against the palaeolatitude settings of the OGUs. We obtained the palaeolatitude measurements from the published literature of palaeomagnetism and, where such data is not available, they were extrapolated from the stage-by-stage reconstruction maps of Ziegler et al. [ 15]. Polynomial regression analysis was then applied to the data matrix in order to reveal the statistical relationship between the species diversity and palaeolatitudes. As shown in Fig. 6, the expected norm of lower latitudes coupled with higher diversity cannot be strictly observed in our data. In most cases, a multimodal pattern appears to dominate. One possible exception to this is the Asselian-

341 Tastubian interval, which demonstrates a higher diversity at the palaeo-tropical zone and a relatively lower diversity towards the subpolar and temperate zones. Asselian-Tastubian

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Figure 6. Relationship of Permian brachiopod species diversity with the palaeolatitude gradient of the Asian-western Pacific region.

4.2. The Boreal Realm As exhibited in Figs 3B and 7, the simple diversity, standing diversity 1 and standing diversity 2 of the Permian brachiopods of the Boreal Realm peaked during the Baigendzhinian to Early Kungurian, then declined rapidly towards the end of the Kazanian-Midian (endGuadalupian). No Late Permian brachiopods are known from the northeast Asian sector of the Boreal Realm, therefore rendering the diversity curves dropping to zero during the Late Permian. The origination pattern shows a peak at the Sterlitamakian-Aktastinian, followed by rapid and steady decline during the Baigendzhinian-Early Kungurian and Kazanian-Midian intervals. As might be expected, the high origination of the Sterlitamakian-Aktastinian

342

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Figure 7. Changing patterns of standing diversity (A), extinction rates (B) and origination rates (C) of Permian brachiopod species and genera of the Boreal Realm through the Permian.

343 interval is accompanied by low extinction rate (Fig. 7B), but the extinction increased in the following stages and reached 100% by the end of the Kazanian-Midian. 4.3. The Gondwanan Realm The diversity, extinction and origination profiles of the Gondwanan Realm (Figs 3D and 8) exhibit two distinct extinction events comparable to the overall diversity and extinction patterns of the Asian-western Pacific region. Simple diversities at familial, generic and specific levels all peaked in the Baigendzhinian-Early Kungurian, but fell dramatically in the Kazanian-Midian (Fig. 3D). The diversity however recovered in the Wuchiapingian, then plunged to an all-time low in the Changhsingian. The Kazanian-Midian extinction appears very pronounced, loosing some 94.3% species and 44% genera as measured by the extinction rate 1. At the species level, this rate may be compared with that of the Changhsingian extinction measured at 95.7%. The origination rate (Fig. 8C) reached its submit in the Sterlitamakian-Aktastinian, seconded by the origination of the Wuchiapingian. Coupled with their higher extinction rates, the Kazanian-Midian and Changhsingian intervals are marked by low origination rates, with standing origination rate of species valued at 21.4% and 2.6% respectively. 4.4. The Palaeo-equatorial Realm The diversity curves of the Palaeo-equatorial Realm (Figs 3C and 9A) is more varied in comparison with those of the Boreal and Gondwanan Realms. Of interest is that the endGuadalupian diversity decline demonstrated by the Boreal and Gondwanan Realms is not well reflected in the Palaeo-equatorial Realm. Instead, there seems to be a significant drop in both species and generic diversity during the Sterlitamakian-Aktastinian, followed by gradual increase of diversity over the subsequent intervals till the end of the Wuchiapingian when the diversity started a rapid decline towards the Permian-Triassic boundary. Likewise, the profiles of the extinction and standing extinction rates are also complicated (Fig. 9B). Although the Kazanian-Midian diversity appears low as revealed by the diversity measures, it nevertheless shows a trend of higher extinction rate at generic level than the other intervals except for the Changhsingian. The Changhsingian extinction is well marked by both diversity and extinction measures for both genera and species (Figs 9A and B), with some 95.9% species and 89% genera disappearing during this interval. The origination rate of the Palaeo-equatorial Realm is also of interest. Despite a low diversity and a relatively high species extinction rate, the Sterlitamakian-Aktastinian exhibits high origination at species level. Origination is also markedly high for both genera and species during the Wuchiapingian (Fig. 9C), following a valley of low origination during the Kazanian-Midian. 4.5. Summary of extinction and origination patterns To summarise, two extinction events and two origination intervals may be noted for the Permian brachiopods across the Asian-western Pacific region, as well as in the different realms. The Kazanian-Midian extinction is well reflected by both the Gondwanan and Boreal brachiopods although it appears to have begun slightly earlier in the former. In the Boreal Realm, the extinction event appears to have been focused at the end of the Kazanian-Midian, eliminating numerous genera and species that were flourishing during the Kazanian-Midian, including, notably, such genera as Magdania, Megousia, Monglosia, Anidanthus,

Spitzbergenia, Cancrinelloides, Attenuatella, Olgerdia, Omolonia, Penzhinaella, Tumarinia,

344

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345

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346 and Tomiopsis. At present, there is no evidence of any recovery from this extinction during the Late Permian in the northeast Asian sector of the Boreal Realm. By comparison, in the Gondwanan Realm the comparable Middle Permian diversity drop appears to have commenced at the Kazanian-Midian and persisted through the interval, resulting in a very low point of diversity at both species, generic and familial levels (Fig. 3D) and over 94.3% species extinction and 44% generic extinction as measured by extinction rate 1. The extinction is marked by the disappearance of many characteristic Early Permian Gondwanan taxa and some antitropical forms, including Tornquistia, Heteralosia, Lialosia, Wyndhamia, Permasyrinx, Reedoconcha, most Taeniothaerus and Trigonotreta species, Comuquia, Magniplicatina, Stereochia, and numerous Tomiopsis species. Unlike the Kazanian-Midian extinction in the Boreal Realm, in the Gondwanan Realm there was an immediate recovery during the Wuchiapingian, as evidenced by 78.3% species origination and 23.5% generic origination. The origination occurred mainly in the peri-Gondwanan region, accompanied by the survival of many long-ranging forms such as Spiriferella, Neospirifer, Linoproductus, Retimarginifera, Plekonella and Cleiothyridina. Unlike the Boreal and Gondwanan Realms, the Kazanian-Midian extinction is not well reflected in the Palaeo-equatorial Realm despite our earlier study based on the brachiopods of South China [5] showing a distinct drop of diversity at the end of the Maokouan (endGuadalupian). The weak manifestation of a possible end-Guadalupian extinction for the Palaeo-equatorial Realm could be interpreted by a number of factors. First, assuming the pattern recognised herein reflects the reality, it would imply that the end-Guadalupian extinction occurred only on continental Pangea (including both Boreal and Gondwanan Realms), with no or only limited effect on the marine faunas of the eastern Tethyan terranes, as has been suggested by Erwin [1 ]. However, this scenario is inconsistent with the Permian brachiopod data of South China, which shows 87% species extinction at the end of the Maokouan TM. This inconsistency requires an alternative interpretation. One obvious factor that may have contributed to this inconsistency is the use of scale, both geographical and stratigraphical, employed for the two different studies. The study of Shen and Shi [5] was based on the South Chinese brachiopod data only and was therefore able to be carried out on a much finer time resolution, using substage rather stage intervals for the Middle Permian. The end-Maokouan extinction recognised by Shen and Shi was in fact concentrated at the end of the Late Maokouan (or Lengwuan), greatly enhanced by the life-depleted Early Wuchiapingian (Laibinian). The following Late Wuchiapingian (Laoshanian) is marked by a boost of numerous new species. In the current study, however, the whole of the Maokouan Stage is treated as one time interval, so is the Wuchiapingian Stage. This treatment, which is necessary and desirable in view of the much broader regional scale of the present study, thus in each case has combined two substages, hence lumping diversities and condensing the pattern of diversity variation which would otherwise be more varied on a finer time resolution. It is therefore reasonable to suspect that an end-Guadalupian extinction of some magnitude also occurred in the Palaeo-equatorial Realm but its manifestation is subdued in our statistical analysis due to the employment of a coarser timescale. In fact, in South China many characteristic Middle Permian elements become extinct during the Guadalupian, including Cryptospirifer, Neoplicatifera, Paraplicatifera, Spirigerella, Urushtenoidea and Monticulifera. On the other hand, a great number of genera also survived the extinction. It is of interest to note that these survivors persisted into the Wuchiapingian, accompanied by invasion into South China of some genera characteristic of the Kazanian-Midian of the Boreal and/or Gondwanan Realms. These immigrant taxa include Attenuatella, Waagenites,

347

Strophalosiina, Strophalosia, and Comuquia. The presence of these Early and/or Middle Permian high-latitude forms in the Late Permian of low-latitude tropical to subtropical regions may suggest that the Palaeo-equatorial Realm may have served as a refuge for some highlatitude but eurytopic taxa during and after the end-Guadalupian extinction. The most severe extinction of the Permian occurred during the Changhsingian. Although this event is not recorded in the northeast Asian sector of the Boreal Realm due to lack of data, the event is evident in both the Gondwanan and Palaeo-equatorial Realms. As measured by standing extinction rate, 73.6% of the Asian-western Pacific Changhsingian brachiopod species and 81.1% of its genera became extinct during the interval, coupled by 1.3% standing species origination and 1% standing generic origination. In the Gondwanan Realm, brachiopods experienced more than 95.7% species extinction and 96.9% generic extinction. Only three species, namely Pustula sp., Linoproductus lineatus, and Retimarginifera sp., are known to have survived into the lowest Triassic [38]. The same event in the Palaeo-equatorial Realm is marked by 95.9% species extinction and 89% generic extinction as measured by the extinction rate 1 statistic. In South China where the marine Permian-Triassic boundary is known to be most continuous in many sections, only 22 brachiopod species of 11 genera (out of 339 Changhsingian brachiopod species) are known to have survived into the lowest Triassic. It is interesting to note that these Permian holdovers are small and thin-shelled in comparison with their Permian counterparts. Two origination episodes are distinct over the six Permian intervals analysed. The first of these occurred during the Sterlitamakian-Aktastinian, the other at the Wuchiapingian. The Sterlitamakian-Aktastinian origination is particularly evident in the Boreal and Gondwanan Realms where the species origination rate 1 reached 86.2% and 83.8% respectively, in comparison with 76.6% in the Palaeo-equatorial realm. Many new species occurred during this interval. For instance, in the Boreal Realm Arctitreta ossokensis, Arctochonetes transitionis, Dyoros semicircularis, several species of Jakutochonetes, Jakutoproductus verchoyanicus, Haelenaeoproductus khubsugulensis, and several species of Rhynoleichus and Tumarinia made their first appearance. In the Gondwanan Realm, there is an even higher number of species first appearing during this interval, particularly in the epicontinental basins of Western Australia. According to the species list provided by Archbold [39], there was some 5.3 times increase of brachiopod species richness across the Tastubian-Sterlitamakian boundary. It is interesting to note that among the new species that first appeared in the Sterlitamakian-Aktastinian strata of Western Australia, they included many immigrants from the peri-Gondwanan Cimmerian Region and even the Palaeo-equatorial Realm [40]. Interestingly, the timing of the invasion of these species into Western Australia coincides with the deglaciation of Gondwana. It is also notable that not only was there is low origination in the Palaeo-equatorial Realm during the Sterlitamakian-Aktastinian when the Boreal and Gondwanan Realms had high originations, the Palaeo-equatorial Realm also exhibits very low species diversity and a higher extinction rate during this interval (Fig. 9). Leven et al. [41] have also recognised a distinct diversity drop across the Sakmarian-Artinskian boundary for the combined data of Fusulinida, Ammonoidea, Brachiopoda and Conodonta from the Tethys, the Russian Platform and North America. They related this life crisis to a global regression. Another interesting feature associated with the Sterlitamakian-Aktastinian origination event is that it does not seem to have succeeded any distinct extinction event in any of the three realms. This is rather unlike the Wuchiapingian origination, which immediately succeeds the end-Guadalupian extinction. The Wuchiapingian origination appears to be a

348

common feature for both the Palaeo-equatorial and Gondwanan Realms. According to the analysis of Shen and Shi [5] based on the brachiopod data of South China on a finer timescale, the Wuchiapingian origination occurred essentially during the Late Wuchiapingian (Laoshanian), with the Early Wuchiapingian being characterised as a period of survival with very low generic and species diversity and almost no origination or recovery. The diversity profile across the Guadalupian-Lopingian boundary is therefore analogous to that of the Permian-Triassic interval where the earliest Triassic, following the Changhsingian extinction, is also characterised by surviving taxa rather than new originations, which did not occur until the Middle Triassic. In the Gondwanan Realm, the Wuchiapingian origination is marked by the first occurrence of many new species, including notably Capillonia brevisulcus, Quinquenella kuwanensis, several species of Neochonetes (Sommeriella) and Neochonetes (Neochonetes), Waagenites

stani, Echinalosia dickinsi, E. millyiti, Liveringia magnifica, Megasteges fairbridgei, Taeniothaerus coolkiliensis, several species of Waagenoconcha (Wimanococncha), Chonetella nasuta, and several species of Costiferina, Stenoscisma, Fusispirifer and Neospirifer. In the Palaeo-equatorial Realm, the Late Wuchiapingian (Laoshanian) origination is centered in South China where a brachiopod fauna of 233 species belonging to 82 genera have been reported, of which 151 species (or 65%) are new [5].

5. S U M M A R Y AND DISCUSSION

(1). On a regional scale, there appears to be a positive correlation between provinciality and species and generic diversity. In the Asian-western Pacific region during the Permian, species and generic diversity were highest when its marine provinciality peaked at 6 provinces. However, we found no direct, consistent, correlation between the palaeolatitude gradient and brachiopod species diversity in the Asian-western Pacific region. (2). The diversity profile of the Permian Asian-western Pacific brachiopod faunas is characterised by two major extinction episodes: one occurring during the Kazanian-Midian (end-Guadalupian) and the other at the Changhsingian. However, the two events appear to differ in geographical distribution, magnitude and duration. The end-Guadalupian extinction is pronounced in the Gondwanan and Boreal Realms. Its manifestation in the Palaeoequatorial Realm is weak but this may be an artifact due to the effect of time-averaging (see discussion above). On the regional scale, the end-Guadalupian extinction appears to have lasted through the whole Kazanian-Midian interval. In the Gondwanan Realm, the event began at or just before the Kazanian-Midian and persisted through the whole interval. In the Boreal Realm, on the other hand, the same event seems to have been focused at the end of the interval. The Changhsingian extinction is recorded only in the Palaeo-equatorial and Gondwanan Realms. This event appears to be much more severe than the end-Guadalupian extinction. Further, the duration of the Changhsingian extinction is also much shorter than that of the end-Guadalupian extinction. This is evident not only from the fact that the combined duration of the Kazanian-Midian interval, being 7 Mys (see Table 1), is 1.5-1.8 times longer than the Changhsingian. A recent study based on the U/Pb zircon dating of the Meishan section in South China has shown that the Changhsingian extinction lasted less than 1 million years and was concentrated in the late Changhsingian [42].

349 (3). The end-Guadalupian and Changhsingian extinctions recognised in this paper based on the brachiopod data of the Asian-western Pacific are in good agreement with previous studies based on both local and global data [3-5, 43-44]. (4). Since the two Permian extinctions are compatible between the three Permian biogeographical realms in the Asian-western Pacific region and consistent with both local and global patterns, they therefore each requires a common mechanism to interpret, and the mechanism in each case seems to be independent of biogeographical control. (5). Numerous theories have been proposed to explain the mass extinctions associated with the Permian-Triassic transition, still no single model has yet been universally accepted. Although it is not our intention to review and evaluate the existing scenarios, it is necessary to point out the close relationship in timing between sea-level movement and the Permian extinctions, particularly as regards the end-Guadalupian extinction. There was a widespread regression in northeast Asia towards the end of the Kazanian-Midian, partly due to the terminal collision of North China with Siberia. This regression is marked by cessation of marine deposition across the entire Angaraland and invasion of the Angara flora into northeastern China [37]. In the Gondwanan Realm, the end-Guadalupian regression is clearly identified by cessation of marine sedimentation and the deposition of coal measures [55]. In South China of the Palaeo-equatorial Realm, the end-Guadalupian regression is marked by a distinct regional disconformity separating the Maokou Formation and the overlying Longtan Coal Measures. Where marine deposition continued across the Guadalupian/Lopingian boundary, such as in the Laibin area of Guangxi Province in southwest China, evidence of regression is still prevailing. There, according to our recent field observation, the topmost Maokouan (Capitanian) unit is a shallow water shoaling deposit of crinoid grainstone, oncolites with vertical burrows of possibly Skolithos ichnofacies. This unit is underlain by black sandy packstones and overlain by interbedded thin-bedded siliceous limestone and cherts. The relationship between eustatic motion and the Changhsingian extinction is far less clear. At the moment, two schools of opinion exist. Teichert [45], Dickins [57], Erwin [46] and Shen and Shi [5] have considered the extinction to be related to an end-Permian regression. Indeed, an end-Permian regression is evident across most parts of the continental Pangea as documented by Holser and Margaritz [47] and Ross and Ross [48]. However, rigorous evidence is lacking to support this scenario in South China where interpretedly continuous Permian/Triassic marine deposition exits in many sections. For this reason, Jin et al. [3] argued that the Lopingian sequence of South China reflects a transgression system and the transgression caused a rapid world-wide flooding resulting in the collapse of the marine ecosystem. Wignall and Hallam [49] and Wignall and Twitchett [50] are also in favour of a latest Permian transgression model and have further proposed that the end-Changhsingian extinction was caused by the spread of anoxic waters during a rapid transgression. However, the exact timing of the end-Changhsingian extinction in relation to the onset of the anoxia event is not clear. Our recent field investigation at several Permian/Triassic sections in South China have revealed that the end-Permian transgression actually began a little earlier than the Permian-Triassic boundary and, in the Laibin section of Guangxi Province, is preceded by a regression as evidenced by the presence of plant fossils and several coal seams within the upper (but not top) part of the Talung Formation (Changhsingian). A similar stratigraphical succession of the Permian/Triassic boundary has also been revealed at the Qubu section in southern Tibet, where the top part of the Qubuerga Formation (Changhsingian) contains plant stems succeeded by black shale with ammonoids. On a more regional scale, this seemingly

350

short-lived late Changhsingian regression appears to be a widespread feature. According to Wignall et al. [51], the Permian-Triassic boundary sequences of Italy, Salt Range, Kashmir and Meishan of South China all "display a significant unconformity or major lithological break immediately preceding the latest Permian main flooding". ACKNOWLEDGEMENTS This study is supported by the Australian Research Council. We thank Professor Neil W. Archbold for his involvement in the compilation of the brachiopod database. We are also grateful to Drs J.M. Dickins, T.A. Grunt and J.B. Waterhouse for reviewing an earlier version of the paper; however we alone are responsible for any errors that may remain.

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41. E.Ya. Leven, M.F. Bogoslovskaya, V.G. Ganelin, T.A. Grunt, T.B. Leonova and A.N. Reimers, Reorganization of marine biota during the Mid-Early Permian Epoch. Stratigraphy and Geological Correlation 4 (1996) 57-66. 42. S.A. Bowring, D.H. Erwin, Y.G. Jin, M.W. Martin, K. Davidek, and W. Wang, U/Pb zircon geochronology and tempo of the end Permian mass extinction. Sci. 280 (1998) 1039-1045. 43. R. Ingavat-Helmcke and D. Helmcke, Permian fusulinacea faunas of Thailand - even controlled evolution. In O.H. Walliser (ed.), Global Bioevents - A Critical Approach. Lecture Notes in Earth Sciences 8. Springer-Verlag, Berlin (1986) 241-248. 44. Z.Y. Yang and 5 others, Permian-Triassic Boundary Stratigraphy and Fauna of South China. Geological Publishing House, Beijing, 1987. 45. C. Teichert, The Permian-Triassic boundary revisited. In E.G. Kauffman and O.H. Walliser (eds.), Extinction Events in Earth History. Springer-Verlag, Berlin (1990) 199-238. 46. D.H. Erwin, The Great Paleozoic Crisis: Life and Death in the Permian. Columbia University Press, New York, ! 993. 47. W.T. Holser and M. Margaritz, Events near the Permian-Triassic boundary. Modern Geol. 11 (1987) 155-180. 48. C.A. Ross and J.R. Ross, Late Paleozoic sea-levels and depositional sequence. Cushman Foundation for Foraminiferal Research Spec. Publ. 24 (1987) 137-149. 49. P.B. Wignall and A. Hallam, Anoxia as a cause of the Permian/Triassic extinction: facies evidence from northern Italy and the western United States. Palaeogeogr. Palaeoclimat. Palaeoecol. 95 (1995) 21-46. 50. P.B. Wignall and R.J. Twitchett, Oceanic anoxia and the end Permian mass extinction. Sci. 272 (1996) 1155-1158. 51. P.B. Wignall, H. Kozur and A. Hallam, On the timing of palaeoenvironmental changes at the PermoTriassic (P/TR) boundary using conodont biostratigraphy. Hist. Biol. 12 (1996) 39-62. 52. J. Tazawa, Middle Permian brachiopod biogeography of Japan and adjacent regions in East Asia. In K. Ishii, K. Liu, X. Ichikawa and B. Huang (eds.), Pre-Jurassic Geology of Inner Mongolia, China. Report of China-Japan Cooperative Research Group, 1987-1989, Osaka (1991 ) 213-230. 53. F.G. Stehli and R.E. Grant, Permian brachiopods from Axel Heiberg Island, Canada, and an index of sampling efficiency. J. Paleont. 45 (1971) 502-511. 54. G.R. Shi and N.W. Archbold, A quantitative palaeobiogeographical analysis on the distribution of Sterlitamakian-Aktastinian (Early Permian) western Pacific brachiopod faunas. Hist. Biol. 11 (1996), 101-123. 55. J.M. Dickins, N.W. Archbold, G.A. Thomas and H.J. Campbell, Mid-Permian correlation. XI r Congr6s International de Strat. G6ol. Carbonif6re Beijing 1987, Compte Redu 2 (1989) 185-198. 56. J.M. Dickins, The mid-Permian: major changes in geology, environment, and faunas and some evolutionary implications. In J.M. Dickins, Z.Y. Yang, H.F. Yin, S.G. Lucas and S.K. Acharyya (eds.), Late Palaeozoic and Early Mesozoic Circum-Pacific Events and Their Global Correlation. Cambridge University Press, Cambridge (1997) 118-125. 57. J.M. Dickins, Permo-Triassic orogenic, paleoclimatic, and eustatic events and their implications for biotic alteration. In W.C. Sweet, Z.Y. Yang, J.M. Dickins, and H.F. Yin (eds.), Permo-Triassic Events in the Eastern Tethys. Cambridge University Press, Cambridge (1992) 169-174.

Persian-Triassic Evolution of Tethys and Western Circum-Pacific H. Yin, J.M. Dickins, G.R. Shi and J. Tong (Editors) 92000 Elsevier Science B.V. All rights reserved.

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A m m o n o i d Succession Model across the Paleozoic-Mesozoic transition in South China* Fengqing YANG and Hongmei WANG Faculty of Earth Sciences, China University of Geosciences, Wuhan, 430074, China

Ammonoids flourished in South China across the Paleozoic-Mesozoic transition. A statistical analysis shows that they demonstrate a clear pattern of stage development. Seven ammonoid extinction events are recognizable from Late Permian to Early Triassic, of which the terminal late-Changhsingian event is the largest with 99% species extinction and 95.2% generic extinction. Most of the seven extinctions coincide with geological boundaries of either series or stages. Each of these events begins with a mass extinction and ends with a newborn burst. Between any two adjacent events is a period of relative stable development. Thus, the evolution of the Permo-Triassic ammonoids seems to have preceded in several cycles, each consisting of newborn explosion-relative stable development-mass extinction. We name this pattern the 'stage model' of ammonoid evolution. Ammonoids began to recover in a stepwise fashion in the Early Triassic after the terminal late-Changhsingian mass extinction. Following a relatively short survival stage, the ammonoids entered periods of recovery and radiation with high prosperity and a biologically and mechanically improved high-level biotic system. The time span in the lead-up-to the ammonoid recovery is about 5 Ma shorter than that of other organisms. There are two kinds of important factors controlling the relative promptness of ammonoid recovery. One relates to the intrinsic (biological) factors of ammonoids (eg., speciation, evolution rate and the ability to adapt to new environments). The other relates to the external or environmental factors such as transgression, regression and the continuing changes of the living environments. The former is considered to be the key to the ammonoid evolution.

1. I N T R O D U C T I O N South China is one of the few places around the world where continuous marine deposition across the Permo-Triassic boundary has been extensively reported. The continuous PermoTriassic stratigraphic successions have recorded the signature of ammonoid prosperity, extinction and subsequent recovery. According to our statistics (Table 1), there existed 27 families, 71 genera and 246 species [1-12] in the Late Permian and 27 families, 105 genera and 334 species [13-22] in the Early Triassic. In this paper, we attempt to examine the occurrence, development, extinction and recovery history of the Permo-Triassic ammonoid faunas of South China in relation to the Palaeozoic-Mesozoic transition and associated geological events to explore ammonoid succession model. * This work is supported by the National Nature Science Foundation of China Project, No: 46932070.

354 2. NATURE OF AMMONOID DEVELOPMENT ACROSS THE PALEOZOICMESOZOIC TRANSITION IN SOUTH CHINA The Middle Permian (Guadalupian) is one of the most prosperous stages of Permian ammonoids in South China, with 37 genera and 87 species so far as reported, among which the Shouchangoceratidae, Paragastrioceratidae and Cyclolobidae are predominant. These families share cake or circle-shaped, involute or semi-involute conch form, strongly ornamented with transverse ribs, tubercles, spines, vertical spiral striations. Often the vertical spiral striations and transverse rib striations interweave together and form nets. A few members of the Cyclolobidae are smooth with no ornamentation on the surfaces. Most ammonoids have goniatitic sutures with binary or lotimate-shaped ventral lobes. Cyclorslobidae members have ceratitic suture or sub-ammonitic suture with multi-lobes. These ammonoids mostly became extinct at the end of Guadalupian, with only a few members persisting into Late Permian. The Wuchiapingian of early Late Permian had 28 genera and 88 species. Their appearances are utterly different from those of the Middle Permian. Anderssonoceratidae and Araxoceratidae are now the dominant families. They are characterized by evolute or semievolute, ratocone or discoidal conchs, ceratitic or goniatitic sutures, ear-shaped prominent umbilical edges and wide, flat venter or carinate venter and ventral keels. By the end of the Wuchiapingian, almost all the members of the families mentioned above died out, with only Konglingites surviving into the Early Changhsingian. The Changhsingian is the second important stage in the development of Permian ammonoid faunas in South China. There existed 43 genera and 158 species. The Tapashanitidae was dominant in Early Changhsingian, with characteristic discoidal, evolute conch, smooth and vaulted venter, and ceratitic suture. These ammonoids developed on their lateral sides strong transverse rib striations and spiral circles with nodes rids inside their shells. In the Late Changhsingian, Pseudotirolitidae and Pleuronodoceratidae became predominant. The shell forms, ornamentation and sutures are similar to those of the Tapashanitidae, but their cross rids developed into nodes at the lateral edge of the venter and shared ridged venture with keels. At the end of the Late Changhsingian, a massive extinction broke out, eliminating all but one Permian ammonoid genus. Five ammonoid genera and 6 species have been discovered during end Changhsingian of South China, including Otoceras and early members of the Ophiceratidae (including Metophiceras, Hypophiceras and Tompophiceras). Otoceras has rotacone with umbilicus shoulder. The early members of Ophiceratidae are characterized by evolute conch form with flat lateral sides, ill-developed ceratitic suture, smooth or ornamented with thin growth lines or thin transverse ribs. All ammonoids extincted at the end of Changhsingian without exr~ection. Ophiceratidae, Gyronitidae and Paranoritidae were abundant during the Indian. In total, 24 genera and 92 species occurred during this interval. They have platcone in different sizes with ceratitic sutures. Not much ornamentation developed on their surfaces. The shells are smooth or only with thin growth lines. By the end of the Indian, only 7 genera survived into late Early Triassic. The Olenekian interval is a major developing stage of Triassic ammonoids. There occurred 25 families, 77 genera and 237 species. Paranannitidae, Flemingitidae, Hedenstroemiidae,

355

Meekoceratidae and Dinaritidae were a little predominant over others. Ammonoids with involute shells outnumbered those with evolute shells, while the number of ammonoids with ribs, lines, node striations was approximately balanced by those with poor or no ornamentation. More ammonoids have arched venture and ceratitic sutures. Ammonoids with ammonoitic suture re-occurred after the Guadalupian, although those with ceratitic suture occupied the leading position. A mass extinction occurred at the end of Olenekian, leaving only 7 genera into the Aninian (Middle Triassic). 51 genera and 146 species existed in the Anisian. Beyrichitidae, Ceratitidae and Longobarditidae are the dominant families. The Anisian ammonoids inherited the nature of late Early Triassic ammonoids but are characterized by the re-occurrence of such ornamentation as lines, ribs and nodes, which last occurred during the Changhsingian. During this interval, the ceratitic suture became a dominant feature, while ammonoids with subammonoitic and ammonoitic sutures also increased. This trend was matched by a decrease of ammonoids with goniatitic suture to the lowest point over the Late Permian to Early Triassic period. To sum up, the development of ammonoids from Middle Permian to Early Triassic is characterized by several well-demarcated stages (Fig. 1 and Table 1 [23-25]). The genera and 80--

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l,"

40--

li,,"7

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0

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G

i

i

i

i

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i

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Figure 1. Diversity, appearance and extinction of P/T ammonoid genera of South China. G=Guadalupian, Chl-Early Changhsingian, Ch2=Late Changhsingian, Ch3=End Changhsingian, I=Indian, O=Olenekian (The abbreviations of geological time in the following figures represent the same meaning as this figure.) species numbers of newborn ammonoids and extinct ammonoids in each stage surpass half of the total genera and species numbers. The newborn curve is in accordance with that of extinction, with major newborn/extinction peaks marking the end of a previous stage and the beginning of a new stage. It thus appears that the ammonoid faunas had evolved according to the stage model: burst of new-born followed by a period of stable development and then a

356 sudden mass extinction". The stage model is best exemplified by the genera and species speciation and extinction rates of the Changhsingian ammonoids. According to the statistics of 597 ammonoid genera compiled by Mt~ller (1957) ~, the average longevity of genera is 1-3 Ma, and that of species is 1 Ma. Haq et al. [26], Harland et al. [27], Yin Hongfu et al. [28] hold that the Late Permian lasted about 5 Ma, the Changhsingian 2.5Ma, and the Late Changhsingian 1.0 Ma. As shown in Table 1, there occurred 93 new species in the Late Changhsingian, hence an average origination rate of 93 species per Ma. This figure is in sharp contrast to the net increase rate of ammonoid at 0.5 species per Ma given by Raup [29]. The former is much greater than the latter, which confirms the newborn explosion. As shown in Figure 2, the amount of ammonoid extinction far surpassed that of survivors at each stage through the late Permian. Raup and Stanley [30] pointed out that the extinction rate of a taxon is inversely related to its average longevity; thus if the lasting time of an ammonoid species is 1 Ma, its extinction rate would be 1 species per Ma. However, our study reveals that there were 102 species becoming extinct in the Late Changhsingian. The species extinction rate is far greater than the predicted rate of 1 species per Ma based on the Raup and Stanley [30] model, which confirmed the sudden mass extinction of ammonoid in Late Changhsingian [3132].

Figure 2. Comparison between survival and origination/extinction of latest Permian and earliest Triassic ammonoid genera and species in South China

3.AMMONOID EXTINCTION EVENTS IN SOUTH CHINA ACROSS THE PALEOZOIC-MESOZOIC TRANSITION The biotic mass extinction across the Palaeozoic-Mesozoic transition is the largest one of its kind in geological history and well expressed by ammonoid faunas [33-36]. So far as reported, there have been 79 ammonoid families and 445 known from the Guadalupian (Middle Permian) to early Middle Triassic around the world [37-53]. A generic diversity vs. time plot (Fig. 3, see also Table 1) of the world-wide data clearly exhibits several notable 1

Yin Hongfu, Monographic teaching material of Cephalopoda, 1964.

357 extinction points, which match well with the temporal patterns of the Late Permian to Early Triassic ammonoid diversity changes of South China. From the Guadalupian to Early Changhsingian, ammonoid genera of South China decreased from 37 to 18 and species declined from 87 to 50, and the diversity reduction pattern appears to have aggravated in a step-wise fashion. Interestingly, while the ammonoid diversity of the world was decreasing during the Late Changhsingian, coeval ammonoid species number of South China reached its zenith at 103. The terminal late-Changhsingian marked a major extinction for the ammnoids of South China, resulting in a very depauperate ammonoid fauna in the end-Changhsingian (with only 5 genera and 6 species). In early Early Triassic, ammonoids increased sharply to 24 genera and 92 species with higher diversity than that of early Changhsingian. In late Early Triassic, however, the ammonoids had evolved rapidly, attaining 77 genera and 237 species with high diversity and abundance. This interval marks the climax of ammonoid development in the Triassic of South China. Following the climax, another ammonoid extinction broke out at the end of the early Triassic.

Figure 3. Temporal variation patterns of diversity, newborn and extinction rates of Permo-Triassic ammonoid genera of the world The overall evolutionary profile of Late Permian to Early Triassic ammonoids of South China displays a deep "V"-shaped valley (Fig. 1), a feature essentially mirroring the world pattern (Fig. 3). Both figures show that ammonoids developed from prosperity to decline, then gradual recovery through Late Permian to Early Triassic. According to the extinction rate, newborn rate and morphological characteristics of ammonoid taxa, seven ammonoid evolutionary events can be identified from Permian to Early Triassic, occurring respectively at the end-Guadalupian, end-Wuchiapingian, terminal Early Changhsingian, terminal Late Changhsingian, end-Indian, end-Olenekian. These events may be categorized into two types

358 in view of their extinction and newborn rates. The end-Guadalupian, terminal Late Changhsingian and end-Olenekian events belong to the same type, whose generic extinction rates are greater than 90% and species extinction rate higher than 99% while their corresponding newborn rates at the beginning of Wuchiapingian, end-Changhsingian and Aninian, respectively, are approximately 90% or above. Obviously, these three events are the major ones among the 7 extinction ammonoid events recognized, while the rest are secondary events but still with generic extinction rate no less than 60% and species extinction rate no less than 70%. In the following sections, each of the three main extinction events is further analyzed. 3.1. The end-Guadalupian ammonoid event Both the extinction and newborn ratios are very high for this event. The extinction ratio of family, genera and species are 68.7%, 90.7% and 100%, respectively. The newborn ratios of genera and species at the beginning of the Wuchiapingian are 92.1% and 97.7% respectively. Only Neoaganides and Demarezites survived from the Guadalupian to the Wuchiapingian. At the same time, the shell morphology of the Guadalupian ammonoids is utterly different from that of the Wuchiapingian members, as explained before. 3.2. The terminal late-Changhsingian ammonoid event This event ranked the severest among the ammonoid events from Permian to Triassic in terms of extinction ratio (Fig.4), with 99% species extinction, 95.2% generic extinction and 88.9% familial extinction. Only one genus, Pseudogastrioceras, survived from the Changhsingian to end-Changhsingian. The corresponding newborn ratios for ammonoid genera and species in the following end Changhsingian are 80.0% and 83.3%, respectively. Late Changhsingian ammonoids of South China occurred in black siliceous facies, siliceous limestone or limestone. Compared with the ammonoids occurring in mudstone or muddy limestone of end-Chnghsingian, the Late Changhsingian ammonoids are bigger in sizes, with higher diversity and abundance. End-Changhsingian ammonoids are smooth or ill-ornamented, with poorly-developed ceratitic suture being dominant. All these traits are obviously different from those of the Late Changhsingian. 3.3. The end-Olenekian ammonoid event This event took place between the early and middle Triassic. And ammonoid suffered another major extinction, marked by 90.9% generic extinction, 99.6% species extinction and 76% familial extinction. Seven genera continued from Early Triassic to Middle Triassic. The generic and species newborn ratios in the following Aninian interval also appear to be high, respectively at 86.3% and 99.3%. The morphological features of Early and Middle Triassic ammonoids are also different. As mentioned above, ribs, nodes on the shell surfaces reappeared and became prominent again in the Middle Triassic (after the Changhsingian). Parallel to this development, ammonoids with sub-ammonoitic and ammonoitic sutures increased while ammonoids with ganiotitic suture declined. The three ammonoid events discussed above are considered main events as far as the ammonoid faunas of South China are concerned. However, if we consider the entire biosphere at the Permo-Triassic transition as a whole, only the terminal late-Changhsingian event appears most conspicuous. This event is well reflected in the ammonoid data of South China: with peak extinction ratios (family 88.9%, genera 95.2% and species 99%), peak extinction speeds (genera 20/Ma, species 102/Ma) among all the ammonoid events recognized herein

359 (Fig. 5). In regards to the other two main events, evolution of other organisms appears less obvious in comparison with the ammonoid faunas.

Figure 4. Extinction and newborn rates of Permo-Triassic ammonoid genera and species in South China. To sum up, the seven ammonois events across the Permo-Triassic transition are characterized by the three aspects hereinafter. (1) Most of the ammonoid events are in accordance with geological boundaries. The two major events (end-Guadalupian event and end-Olenekian event) coincide with the boundary of series, the end-Changhsingian secondary event marked the Permo-Triassic boundary, while the other secondary events lie at the stages boundaries. Of note is that the biggest ammonoid event (terminal Late-Changhsngian event) took place lower than the Permo-Triassic boundary Therefore, the ammonoid events are of great importance in dividing strata and determining geological boundaries. (2) Besides, each ammonoid event begins with a mass extinction of genera and species and ends with the burst of newborns. Between the events the taxa developed stably. As a result, ammonoid faunas appear to have undergone several cycles, each consisting of an

360

explosive newborn stage, followed by a relative stable development, and terminated by a mass extinction event. We refer to this cyclic development as the 'stage model of ammonoid evolution'. (3) The seven events broke out in such turns as followings: Major, Secondary, Secondary, Major, Secondary, Secondary, Major \ J ~. J -y-y Late Permian Early Triassic There exit some regularities in view of their happening turns. Two secondary events occurred between the two adjacent major events. However, what kind of relation shi between the three major events and the adjacent smaller events is needed to be furtherly discussed. Z~

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Figure 5. Comparison of various extinction measures of ammonoid genera of South China across the Permo-Triassic transition.

361 4.CHARACTERISTICS OF AMMONOIDS ASSOCIATED WITH THE SURVIVAL, RECOVERY AND RADIATION STAGES The terminal Late-Changhsingian mass extinction severely destroyed the ecosystem in the whole region of South China including that of ammonoid. Many ammonoid taxa disappeared such as families of Psedotirolitidae, Pleuronodoceratidae, Huananoceratidae, Xenodiscidae, Maximitidae, Marathonitidae, and Shouchangoceratidae. Only a few members of the Paragastrioceratidae and Episgecetatidae families survived the crisis as disaster forms. 4.1. The survival interval

This

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Early

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Pseudogastrioceras survived the terminal Late Changhsingian. The disasters forms include Hypophiceras, Tompophiceras, Metophiceras of the Ophiceratidae and Otoceras of the Otoceratidae. In the Late Changhsingian preceding the mass extinction, ammonoids of South China are believed to have lived in a warm, quiet and deep basin setting within a shallow sea with normal salinity [54]. In this environment, the swimming abilities of most ammonoid genera are poor since it is unnecessary to swim quickly for survival in a stable ecosystem with few competitors, abundant food and many endemic members. Their living environments are probably equal to or a little deeper than BA4, BA5 of the brachiopod community. The terminal Late-Changhsingian mass extinction almost destroyed the whole ammonoid ecosystem. Only the Hypophiceras community consisting of Palaeozoic survivors and some newborn disaster members existed in the Early Triassic. However, the abundance and diversity of the community was still very low in the aftermath, lacking endemic elements (but worldwide-spread members were still prevalent). During the survival, most ammonoids lived in remnant shallow marine basins with little oxygen. Their niches are probably equal to BA2 and BA3 of brachiopod communities. In general, the ammonoids lived in a stable environment, with small-scale but highly frequent undulation [55]. Most ammonoid fossils are found as flattened imprints, with no obvious biogeographical provincialism. The bottom sediment deposited in the early transgression [32,56] during the survival interval was in a reducing state, which restricted the survival and newborn of normal benthonic organisms. Thus, swimming ammonoids living in the deeper-water environment dominated at this stage, and opportunistic species were also in great prosperity. However, surviving individuals are generally small in size with low abundance and diversity, probably reflecting the control of the lack or insufficient supply of oxygen in the environment. The ammonoid community structure at this time is simple in that the surviving members attained no significant role and rapidly declined towards, and then died out in the End Changhsingian. The survival interval marked the beginning of a recovery interval despite low recovery rate. 4.2. The recovery interval

The recovery interval spans the Indian of Early Triassic and is characterized by higher diversity and greater abundance compared with the survival interval, although the shell characteristics of the two intervals are similar. Eight newborn ammonoid families emerged during this interval (Fig. 6), and all the members of the Ophiceratidae and Otoceratidae from the survival interval died out at the end of this stage. Besides, the fiat board-shaped venter appeared, ammonoids with ceratitic suture increased, and the earliest sub-ammonitic suture occurred during this interval.

362

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Figure 6. Diversity and appearance of Permo-Triassic ammonoid families of South China A relatively stable shallow sea basin was formed in South China at this stage as a result of the expansion of the Early Triassic transgression and the subsequent deepening of sea-water. At this time ammonoids began to thrive with speciation surpassing extinction rate and the newborn types becoming dominant, despite a few survival and disaster taxa still remaining. At the same time, endemic species also emerged and became increasingly common, and the ammonoid communities diversified with increasingly more complicated structures. Typical communities of this time are the Ophiceras community, Gyronites community and Koninckites (or Flemingites) community. Despite the recovery of complicated communities, ammonoid provincialism at this stage remained low. 4.3. The radiation interval

The interval spanning Olenekian stage witnessed the radiation of ammonoid faunas in South China and characterized the blooming stage of Triassic ammonoids. The number of newborns greatly increased with high abundance, diversity, newborn ratio and newborn speed (Fig. 7), marking a period of great prosperity. Ammonoids of this interval are chiefly with involute shells and ceratitic suture. More and more ammonoids have flat-board venter with strong ornaments such as rough ribs and nodes on the lateral side. For the first time in Triassic ammonoids owned ammonitic suture, and the shell ornaments became more complicated and diversified. The community types and numbers surpassed those of the Permian and the community structures became complex as the new ecosystem was gradually improved. Ammonoid communities that characterized the radiation stage include the Meekoceras community, Anasibirites community, Paranannites community (or Columbites-Proptychitoides community), Tirolites-Dinarites community, Procarnites community (or Subcolumbites community), and the Tirolites-Dinarites community. These communities succeeded in occupying all the ecological habitats of the shallow sea environment. Most communities inhabited in the shallow or deep areas of the shallow marine basin. Some communities (eg.,

363

Tirolites-Dinarites community) lived in a closed or semi-closed shallow sea area or at the edge of a platform where the environmental condition changed frequently and at times violently. It is probably due to this diversity and stability of habitats that the Olenekian ammonoids reached their climax in diversity and abundance after the end-Changhsingian mass extinction. There are 17 newborn families. Six families that originated from the recovery stage bloomed in the radiation interval (Fig. 6). In addition, endemic elements increased rapidly, coupled by an increasing biogeographical differentiation.

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5. DISCUSSIONS ABOUT A M M O N O I D E V O L U T I O N AFTER T E R M I A N L LATE C H A N G H S I N G I A N MASS E X T I N C T I O N 5.1. Duration of the survival interval following the terminal Late-Changhsingian mass extinction It took nearly 10 Ma for all kinds of organisms to recover from the end-Permian mass

364 extinction [56-57] and to establish a new ecosystem in the Mesozoic. However, the spans of survival, recovery and radiation intervals varied from organism to organism, among which ammonoid took the shortest to recover. Ammonitic span of survival, recovery and radiation intervals is 1.25Ma, 3.75 Ma and 5.0 Ma, respectively. From survival to recovery ammonoids took 5.0 Ma, which is only half of that of other organisms. 5.2. The upper and lower boundaries of the recovery interval following the terminal lateChanghsingian mass extinction From the terminal end-Cahnghsingian ammonoid mass extinction to late Early Triassic ammonoid radiation, four ammonitic events occurred in turns: the terminal lateChanghsingian event, the end-Changhsingian event, the end-Indian event and the endOlenekian event. The end-Changhsingian event resulted from the prosperity and subsequent disappearance of survivors and opportunistic taxa, which formed the lower boundary of the recovery interval. The end-Indian event occurred between the early and late Early Triassic. Many genera and species became extinct owing to the falling of the secondary sealevel during transgression in the event. Then the sea level continued to rise. Ammonoid genera and species from the Dienerian developed greatly during the Smithian and Spathian. At the same time, there occurred many new families, new genera and new species. The newborn ratios of genera and species were 88.2% and 97%, respectively, signalling the onset of a rapid radiation interval after the terminal Late-Changhsingian ammonoid mass extinction. So the terminal Dienerian event marked the upper boundary of the recovery interval. 5.3. Factors controlling the timing and speed of ammonoid recovery Ammonoids were severely destroyed during the terminal Late-Changhsingian mass extinction. But how could the ammonoids recover faster than other organisms after the mass extinction? We believe that both intrinsic (biological) as well as external (environmental) factors have contributed to the prompt recovery. 5.3.1. Intrinsic factors The evolutionary speeds of different organisms are affected by speciation and extinction at different degrees. As a result, in a specific environment some organisms evolve quickly, while others evolve slowly. The relatively short duration in the lead-up-to the ammonoid recovery probably resulted from the high evolution rate and fast speciation speed of the ammonoids during their adaptive radiation. After almost all ammonoids died out at the termianl LateChanghsingian, extraordinary adaptive radiation of ammonoids broke out following their survival and radiation periods. By the end of Early Triassic (after a duration of 10 Ma), 237 ammonoid species emerged, that is 23.7 new species originated in every 1 Ma. Stanley [58-59] reported that those taxa with a high speciation rate generally have a high extinction ratio. In the Early Triassic the extinction ratio, extinction rate and extinction speed of ammonoids were all high. Therefore, it is not surprising to see a high speciation rate associated with the rapid extinctions. Raup and Stanley [30] and Raup[29] demonstrated that extinction ratio can be expressed as the reciprocal of species surviving time. While general Mesozoic ammonoid species lasted 1 Ma on average, the endemic species each appears to have lasted for only 0.5-0.7 Ma. According to the relationship between extinction ratio and surviving time of species, the species extinction ratio of Mesozoic ammonoids (E) is 1. The net increasing rate (R) of ammonoid species number is calculated to be 0.5, and the speciation rate S (-R+E) is 1.5. The speciation ratio and extinction ratio in the animal kingdom are

365 closely connected with each other during adaptive radiation. Because of the high ammonoid extinction ratio, its speciation rate is correspondingly high and surpasses that of most other animals with the exception of trilobites (S=1.52). Haldane[60] holds that the evolution rate was determined by the site numbers of chromosome complement (measurement of organism complexity) and their stage numbers of mutation (productivity) and generation cycle. That is to say, the evolution rate goes up with the increase of adaptive complexity of different animals. Stanley [59] acclaimed that the level of advanced behavior also affected the speciation rate. The advanced complex behaviors probably represented the benefit of adaptation to environment. However, specialized adaptation would make species liable to extinction in the wake of rapid environmental change. So biotic complexity and particular behaviors are both related positively to high extinction ratio. Subtle changes of complex behaviors would lead to production separation and speciation easily. Ammonoid belonged to the complex-structure type among invertebrates with short generation cycle, advanced life-style and preying behavior, which determined its high evolutionary rate. Some scholars [59] said that the speciation rate was inversely related with the size of population: if a population spreads widely, its speciation rate is low; whereas an unstable small population would have a relatively high speciation rate. In the early Early Triassic opportunic species flourished in a wide range of habitats, therefore their speciation rate was low. By the late Early Triassic, endemic members increased greatly in number in a relative narrow range of habitats, so the speciation rate was high (Fig. 7). Other scholars [58] deemed that the eating patterns were also connected with the evolutionary rate: animals with a special eating pattern would have a greater chance of becoming extinct than animals with a general eating pattern (other conditions being equal). The evolution rate of suspension fedders is greater than that of sediment feeders. Ammonoids are carnivores living on broad ocean, or benthons living on capture, so their evolution speed is correspondingly high. Therefore, the evolution speeds of the Triassic outer-oceanic or benthonic ammonoids are much higher than those of endobionts or shallow endobionts. 5.3.2. External (environmental) factors Like many other invertebrates, the prosperity and decline of ammonoids are closely related to the rise and fall of sea level [61]. Study by Yang Zunyi et al. [32] shows that eustatic change is a key factor controlling the terminallate-Changhsingian mass extinction and its subsequent recovery and radiation (Fig. 8). At the beginning of transgression in the end-Changhsingian, the environment condition is not very steady. Abundant opportunistic taxa existed in low-diversity and stenotopic members occupied most of the marine environments. The Hypophiceras community (including such main members as Hypophiceras, Metophiceras, Tompophiceras, Otoceras, Psedogastrioceras etc.) had a special adaptive ability to the oxygen-deficient bottom environment of a restricted, reducing shallow ocean and thus thrived and greatly restrained the development of other organisms. It was also this special adaptability that led them fail to recover and finally become extinct at the end of the survival interval when the environment stablized. Some opportunistic taxa of the Ophiceras community (main members including Ophiceras and Lytophiceras) living in a shallow sea greatly developed in the survival interval. In the early Early Triassic, transgression continued to extend with deepening sea-water. As a result, the living environment for ammonoids was improved gradually. With the enlargement of ecospace and the diversity of habitats, intensity of species competition

366 decreased while the radiation improved under the suitable environment. The Gyronites and Koninckites-Flemingites communities were best developed; eurytopic and moderately stenotopic members increased steadily. At the same time, symbiotic fossils such as conodonts and bivalves also expanded. The sea-water shallowed by the end of Early Triassic, resulting in the end-Indian secondary ammonoid event. Regression ', Transgression i

I

Ch3 Ch2

m

) I

0

10

I

20

i

30

i

40

I

50

I

I

I

60

70

80

Genera

Figure 8. Influence of transgression and regression on the diversity of upper Permian lower Triassic ammonites in South China (transgression and regression curve after WangYigang, 1988) After a short period of adjustment, the sea-level rose again and reached to its climax of the prolonged transgression in the late Early Triassic. With it the environment returned to normal condition. As a consequence, ammonoid surviors and new genera and species developed quickly after they experienced variation and innovation. The speciation and evolution rates also rose sharply. Because of and after the mechanic adjustment and innovation, the ammonoids were able to further expand their ecospace, improved radiation and adaptability, and consequently reached their summit development. In the deeper part of shallow sea thrived the Owenites and Anasibirites communities, while in saline continental sea areas thrived the Tirolites-Dinarites commnity, and in the deep water environments of the shallow marine basin developed the Columbites-Subcolumbites community. At the end of the Early Triassic sealevel dropped on a large scale, resulting in the absence of Middle Triassic ammonoids in the lower Yangtze region. Only the ammonoid communities living in saline continental seas were found in the upper Yangtze region. The living space of ammonoids declined and the habitat quality deteriorated (e.g., high salinity, high water temperature, and high turbulence), causing competition between ammonoid species to intensify. As a result of this steepening of environmental pressure, the ammonoid diversity dropped, marking the onset of yet another major ammonoid extinction between Early and Middle Triassic. It should also be noted that the above-mentioned regression was accompanied by volcanic activities as evidenced by the volcanic ejecta--"green-gram- like" beds.

367

6. S U M M A R Y In conclusion, there is a clear ammonoid succession across the Palaeozoic-Mesozoic transition in South China. From the Late Permian to Early Triassic, the ammonoid faunas of South China as a whole underwent a prolonged process from prosperity to decline, followed by gradual recovery to prosperity again. Seven smaller-scale events have been recognised within this large cycle, each of which began with a newborn burst, through a stable development stage, and terminated with a mass extinction. No matter the cycle is small or large in terms of duration or intensity, they all confirm to the stage model of ammonoid succession. Some striking features of the ammonoid evolution after the terminal late-Changhsingian mass extinction include: (1) Overall, the ammonoid diversity increased and the biotic system became mature; (2) The duration in the lead-up-to the recovery of the ammonoids is only half that of other organisms. The upper and lower boundaries of the recovery interval are defined by two corresponding ammonoid extinction sub-events; and (3) Two types of factors appear to have controlled the promptness of the recovery of ammonoids. One is related to the biological variables of the ammonoids themselves including speciation speed, evolution rate and adaptability to environment. The other factor bears on influence of such environmental parameters as transgression, regression and the pace of change of habitats. In comparison, the intrinsic, biological variables appear to have had more effective control on the mode of evolution of the Permo-Triassic ammonoids, as indicated by the fact that some ammonoids died out, while others in the same ecosystem survived and developed across the Permian-Triassic transition.

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(1994) 1340-1344. 37. Bando Y., On the Otoceratidae and Ophiceratidae. Sci. Rep. Tohoku Univ. Sendal Japan, Spec., No.6 (1973) 337-351. 38. Bando Y., Upper Permian and Lower Triassic ammonoids from Abadeh, Central Iran. Mem. Fac. Educ Kagawa Univ. Part. II, V.29, No.2 (1979) 103-138. 39. Bando Y., On the Otoceratacean Ammonoids in the Central Tethys with a note on their evolution and migration. Mem .Fac. Educ Kagawa Univ. Part .lI, V.30, No. 1 (1980) 23- 49. 40. Bando u Lower Triassic ammonoids from Guryul Ravine and the Spur three kilometres north of Barus. Paleont. Indica., New Set. No.16 (1981) 135-178. 41. Furnish W.M., Glenister B.F., Kummel B., Spinosa C., Sweet W. & Teichert C., Reinterpretation of ceratitic ammonoids from the Greville Formation, New Zealand. Geol. Mag. V.113, No.1 (1976) 39-46. 42. Glenister B.F. and Furnish W.M., The Permian ammonoids of Australia. Jour. of Paleon., No.35 (1961) 673-736. 43. Kummel B., Cephalopoda Ammonoidea. In: R.C. Moore (ed.) Treatise on Invertebrate Paleontology Part L. Mollusca 4. Geol. Soc. Amer. & Univ. Kansas. (1957) 1-131. 44. Kummel B., Ammonoids of the Late Scythian (Lower Triassic). Bull. Mus. Comp Zool. Harv., V.137, No.3 (1969) 311-702. 45. Kummel B., Ammonoids from the Kathwai Member, Mianwali Formation, Salt Range. West Pakistan. In: Stratigraphic boundary problems: Permian and Triassic of West Pakistan. Univ. Press. Kansas. (1970) 177-192. 46. Miller A.K. and Furnish W.M., Permian ammonoids of the Guadalupe Mountain Region and adjacent areas. Geol. Soc. of Amer. Spec. Paper, No.26 (1940) 1-236. 47. Nassichuk W.W., Furnish W.M. and Glenister B.F., The Permian ammonoids of Arctic Canada. Geol. Sur. of Canada Bull., No.131 (1964) 1-56. 48. Popov Y.N., Triassic ammonoids of northeast U.S.S.R. Trans. Sci. Res. Inst Geol. Arcti. Moscow, No.79 (1961) 1-178. 49. Ruzhencev V.E. & Sarycheva T.D. (eds.), The development and succession of marine organisms at the Paleozoic-Mesozoic Boundary. Trans. Palaeont. Inst. USSR Acad. Sci., No. 108 (1965) 1-431. 50. Shevyrev A.A., Triassic ammonoids of southern U.S.S.R. Trans. Paleont. Inst. Acad. Sci. U.S.S.R., No.l19 (1968). 51. Tozer E.T., Xenodiscacean ammonoid and their bearing on the discrimination of the Permo-Triassic boundary. Geol. Mag. (London) No.106 (1969) 348-361. 52. Tozer E.T., The significance of the ammonoids Paratirolites and Otoceras in correlating the PermianTriassic boundary beds of Iran and People's Republic of China. Canada Jour. Earth Sci., V.16, No.7 (1979) 1524-1531. 53. Zakharov Tu.D., Lower Triassic ammonoids of East USSR. Nauka, Moskva. (1978) 1-224. 54. Yang F.Q., A preliminary review on palaeoecology of Late Permian Changxingian ammonoids in South China. Act Paleont Sin., V.31, No.3 (1992) 360-370. 55. Wang Y.G., An introduction to palaeoecology of Triassic ammonites of China. Act. Paleont Sin., V.27, No.3 (1988) 346-367. 56. Tong J.N. The ecosystem recovery after the End-Paleozoic mass extinction in South China. Earth Sci., V.22, No.40 (1997) 373-376. 57. Rong J.Y., Fang Z.J., Chen X. et al., Biotic-Recovery-first Episode of Evolution after Mass Extinction. Act Pal. Sin., V.35, No.3 (1996) 259-271. 58. Stanley S.M., Macroevolution-Pattern and Process. W. H. Freeman and Company, San Francisco (1979) 1-301. 59. Stanley S.M., Macroevolution. In: Rong J.Y., Fang Z.J. and Wu T.J. (eds.), Selected Papers of Theoretical Palaeontology. Nanjing University Press (1990) 50-67. 60. Haldane J.B.S., The causes of evolution. Harper New York, (1932). 61. Kennedy W.J., Ammonite evolution. In: Hallam A. (ed.), Patterns of Evolution as Illustrated by the Fossil Record. Amsterdam, Elsevier. (1977) 251-304.

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Persian-Triassic Evolutionof Tethys and WesternCircum-Pacific H. Yin, J.M. Dickins, G.R. Shi and J. Tong (Editors) o 2000 Elsevier Science B.V. All rights reserved.

371

On zonation and evolution of Permian and Triassic conodonts* Xulong LAI a and Shilong MEI b a

b

Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, China Faculty of Earth Sciences, China University of Geosciences, Beijing 100083, China

Evolution and zonation of Permian and Triassic conodonts are newly delineated with acknowledgment of conodont provincialism. Ten evolutionary stages and eleven evolutionary events are recognized for the Permian and Triassic. Among them, four stages and four events are Permian and six stages and seven events are Triassic. Two patterns of evolution, namely Substitute Pattern and Extinction- Survival- Recovery Pattern, are suggested for the conodont evolution crises in the Permian and Triassic. Two types of Permian conodont zonations are summarized in term of warm water and cool water nature. Based on the materials from South China, a warm water Permian conodont zonation is established and its mutual correlation with that for cool water provinces is made. Twenty six Triassic conodont zones are proposed for the purpose of global correlation. In ascending order, they are: Hindeodus parvus zone, Isarcicella isarcica zone, Clarkina carinata zone, Neospathodus kummeli zone, Neospathodus dieneri zone, Neospathodus cristagali zone, Neospathodus pakistanensis zone, Neospathodus waageni zone, Neogondolella milleri zone, Neospathodus triangularis zone, Neospathodus homeri zone, Neogondolella jubata zone, Chiosella timorensis zone, Neogondolella regale zone, Neospathodus kockeli zone, Neogondolella constricta zone, Neogondolella mombergensis zone, Budurovignathus mungoensis zone, Paragondolella polythiformis zone, Metapolygnathus nodosus Zone; Epigondolella abneptis zone; Epigondolella multidentata zone, Epigondolella postera zone, Epigondolella bidentata zone, Misikella hernsteini zone and Misikella posthernsteini zone.

1. P R O V I N C I A L I S M OF P E R M I A N AND TRIASSIC C O N O D O N T S 1.1. Provincialism of Permian conodonts

Provincialism of Permian conodonts has not been well recognized previously. Mei and Wardlaw [1] found that inadequate attention to conodont provincialism has caused serious

9This work is supported by the National Natural Science Foundation of China Project, No:49632070

372 problems in the Permian standard conodont zonations proposed by previous authors [2-4]. Based on accumulated conodont data, Mei et al.[5] recognized three provinces of Permian conodonts. They are referred to as the North Cool Water Province, the Equatorial Warm Water Province and the peri-Gondwana Cool Water Province (Figure 1). The North Cool Water Province is marked by Gondolelloides from Vancouver Island, British Columbia and Arctic Archipelago of Canada and the Urals, Novaya Zemlya, Soviet Arctic [6-7] and Rabeignathus from the Phosphoria Basin and Kansas of USA [8] in early Cisuralian, by dominance of Neostreptognathodus and no or rare Sweetognathus in late Cisuralian [9-13], by dominance of Merrillina and Pseudoclarkina in Guadalupian and Lopingian, and absences of Sweetognathus in Guadalupian and Iranognathus in Lopingian [1,14-22]. The Equatorial Warm Province includes South China, North China, Japan, Iran, Pamir, Hydra Island of Greece, Italy and West Texas of USA. It is characterized by absences of Gondolelloides, Rabeignathus and Vjalovognathus in Cisuralian and abundance of Sweetognathus and Pseudosweetognathus in late Cisuralian [23-26], and marked by Jinogondolella and Sweetognathus in Guadalupian [27-30], and Clarkina and Iranognathus in Lopingian [31-36]. The peri-Gondwana Cool Water Province includes the Canning and Carnarvon basins of Australia, western Timor, Selong of Tibet, the Salt Range and Kashmir. It is represented by Vjalovognathus, Merrillina and Rabeignathus in Cisuralian [37-40], Vjalovognathus, Merrillina, Pseudoclarkina and rare Sweetognathus in Guadalupian [26,41] and Vjalovognathus and Merrillina in Lopingian [40]. It is noteworthy that Iranognathus and Clarkina invaded into the Salt Range during the Wuchiapingian, which may indicate a possible global warming in Wuchiapingian. The similar phenomenon may exist in the type area of the Cache Creek Complex, south-central British Columbia, Canada, where Iranognathus co-exists with Pseudoclarkina ?jesmondi [42]. 1.2.Provincialism of Triassic conodonts

It is commonly accepted that global temperatures increased after the late Permian. Due to this rise in temperature, the provincialism of Triassic, especially Early Triassic, conodonts is no longer as clear as that of Permian conodonts. By explaining the absence of the Alpine Gladigondolella tethydis assemblage in the Germanic Muschekalkr, Huckriede [43] was the first to note Triassic conodont provincialism. After comparing the data from the central German Muschalkalk, the Alpine and the western North American areas, Mosher [44] determined the conodont provincialism of the Middle and Upper Triassic. He divided the Middle Triassic conodonts into three types: the Muschelkalk, the Alpine and the North American; and the Upper Triassic conodonts into two types: the Alpine and the North American. Regarding the Permian- Triassic (P/T) boundary conodonts, Matsuda [45] and Mei [5,46] reported the peri- Gondwana Cool Water (the peri- Gondwana Tethys Province of Matsuda) and the Equatorial Warm Water provinces ( including the Tethys Province of Matsuda). Paull et al. [47-48] also considered the Lower Triassic conodonts to be either trans-

Permian Subdivisions

Evolutionary Stages and Major Distribution of C o n o d o n t s

Equatorial Warm Water Province

C. postwangi C. changxingensis

g

C subcarinataC. wangi

cool water:

Pseudoclarkina, Merrillina

I

C. transcaucasica

,

C. dukouensis

9 ,~ _

.~

~

~-Event 4 " d ~ Conodon-(R-t~ne 4 cool water:

U

Mesogondolefla

Wordian

,

C. ~ ~ r w i n i | J. granti I J. xuanhanensis c~" ~ ~. prexuanhanensis

"

"

~

,g

~

Merrillina

J. postserrata

warm water:

J. aserrata

Jinogondolella, Sweetognathus

Roadian

M. aft. J. nankingensis

M. sp. nov. A

Neostreptognathodus

M. zsuzsuannae

warm water:

Neostreptognathodus,.____ M. siciliensis Pseudosweetognathus

N. ex sculptusN. pequopensis

Event 2 "~':_"

o . . . . . . . .~

.~ ~

J. nankingensis

cool water:

"~

C.

postbitteri J. croftJ

Conodont Stage 2

Sw. whitei

Sweetognathus Mesogondolella

Sw. inomatus

J. xuanhanensis J. prexuanhanensis J. altudaensis J. shannoni

C. subcarinata

J. postserrata

guangyuanens~

i

~

C. cf. subcarinata

r

C. fiangshanensis

C. asymmetrica C. dukouensis

.~

European Zechstein Formation and Greenland

C. asymmetrica

Ps. rosenkrantziMe. divergens

Sw. O.

Me. praedivergensPs. bitted Ps. bitten-Me, arcucristata

' T

nankingensis

N. sulcopficatus N. prayi-M . . . . . . a . . . . N. exscluptusM. zsuzsannae

C. a s y m m e ~ c a C. dukouens~

~ngshanensis

J. aserrata J.

~" tFanscaucasica

~ guangyuanensis

' Me. praedivergens bitted-arcucristata Vjalovognathus Sw. cf. hanzhongensis

Ps. phosphoriensisPs. prolongata N. newelli-Ps, gracilis N. sulcoplicatus

i

B

,

N. 9 exsculptus-M, gujioensis, ~_ N. pequopensis

Sw. whiteiM. bisselfi

~

~

N prayiM. idahoensis N. exsculptustl4. idahoensis N. exsculptus

N. pnevi

N. pequopensis

N. pequopensis

Sw. whitet-

Sw. whitei

M. bisselli M. bisselfi-M, visibifis St. florensis

St. barskovi

Unnamed

~ Vjalovognathus - 9 Memllina sp. nov.

C. leveni

,

M. dentiseparata Ad. paralautus

. i~vent 1 ~J~_Conodont Stage 1 Adetognathus Streptognathodus

"~

Jnit .55

E !

C. s u b c a d n a ~

C. tmnscaucasica

I

C o n o d o n t Stage 3

i

C. yini C. postwangi changxingensis

North. Cool Water (NP) Great Basin-Rocky Mtns.

C. oden~lis

C. guangyuanensis C. leveni C. asymmetrica

Clarkina, Iranognathus

,

"~

r~

C. inflecta C. orientalis

w a r m water:

~

C. cha ngxingensis

?

Salt Range

Julfa, Iran

C. yini

Conodont Stage 5

._

peri-Gondwana (GP)

Abadeh, Iran

Texas, USA

St. nevaensis St. isolatus

]

St. postconstr~ctus St. barskovi St. fusus St. nevaensis St. isolatus

M. lata-Sw, merrilli

'M. pseudostnata-M, striata M. simulata-St, fusus st constdctus-M, bel/a'c/ontae" St cnstellans St. wabaunsensis

Fig. 1 Provincialism,evolutionary stages and zones of Permian conodonts and their global correlation. The following abbreviations are used for conodonts" C. =Clarkina, L = Iranognathus, J . = Jinogondolella, M. = M e s o g o n d o l e l l a , N. = N e o s t r e p t o g n a t h o d u s , Ps. = P s e u d o c l a r k i n a , St. = Streptognathodus, Sw. = S w e e t o g n a t h u s

374

Tethyan or circum- Pacific in distribution. Using computerized worldwide Triassic conodont data, on the other hand, Charpentier [49] concluded that there is little support for provincialism of Triassic conodonts. Though the intensive study of Lower Triassic conodonts and lithofacies in Svalbard (Arctic) and Nepal (Tethyan), Clark et al. [50] and Hatleberg et al.[51] obtained approximately 20 species from the above sections, but there are few species in common. However, both Arctic and Tethys sections have 7 species in common with that of areas in the Western United States, and demonstration of equivalency of stages and zones is possible by using the U.S. sections as intermediates. To explain the markedly different Lower Triassic conodont faunas in Svalbard and Nepal, they considered the faunal difference due to distinct biofacies rather than provincialism. With the accumulation of conodont data during recent years, it is now time to set up a database for evaluating conodont distribution and provincialism. However, because most Triassic index conodonts are cosmopolitan species, as illustrated below, it implies provincialism is no longer an important factor influencing the distribution of Triassic conodonts. Paleoenvironment is most likely the major factor controlling the distribution of Triassic conodonts.

2. ZONATION OF PERMIAN AND TRIASSIC CONODONTS 2.1. Zonation of Permian conodonts

Distinct conodont provincialism during the Permian, especially the Kungurian through the Changhsingian, prevents the development of a single standard zonation. As a result, two types of Permian conodont zonations were recognized, one is of warm water, and the other is of cool water (Figure 1). The most complete Permian conodont zonation of warm water was established in South China, which contains 32 conodont zones. Of which, in descending order, the 4 zones of Changhsingian were based on materials mainly from Meishan section, Zhejiang, South China [33,52], Abadeh section, central Iran and Kuh-e-Ali Bashi section, northeastern Iran [35]; the 8 zones of Wuchiapingian were based on materials mainly from Dukou and Nanjiang sections in northeastern Sichuan as well as Tieqiao and Penglaitan sections in central Guangxi [31-32,34], and all of which except the lowermost zone were also well developed in Iran (Figure 1); the 8 zones of Maokouan or Guadalupian were based on materials mainly from Dukou and Nanjiang sections in northeastern Sichuan, Fengshan, Tieqiao and Penglaitan sections in central Guangxi [28,32,34], and all of which except the youngest dinogondolella granti Zone have been also well recognized in Texas, USA [53](Figure 1); the 12 zones of Cisuralian (equivalent to Chuanshanian and Chihsian in South China) were based on materials from Nashui and Ziyun sections, southern Guizhou [54,55]. It should be pointed out that Artinskian and Kungurian conodont taxonomy and zonation are the weakest parts in the study of Permian conodonts and need further investigation. The Permian conodont zonation of cool water was based on materials from the Urals [10], the Great Basin in the United States [15-17,30], and the Salt Range [26,41 ]. Figure 1 also shows correlation of

375 the 31 conodont zones in South China with those in the United States, the Salt Range, Iran and the Urals. 2.2. Zonation of Triassic conodonts

Since Sweet et al.[56] proposed 22 international conodont zones in the Triassic, based on worldwide materials, and established the framework for Triassic conodont zonation, a lot of Triassic conodont material has been accumulated during recent years, and many authors [5761] have discussed these conodont zonations. As mentioned above, fortunately, conodont provincialism is not strong during the Triassic and most genera and species are widespread. This lays a foundation to establish a global Triassic conodont zonation. According to the regulations of global correlation, herein 26 Triassic conodont zones based on worldwide materials (Fig.2) are proposed. In ascending order, they are discussed as follows: Hindeodus parvus zone: This zone can be recognized at 27 localities of 11 provinces in South China [62-64]; Selong section in Tibet [65-66]; Guryul Ravine section in Kashmir [6769]; Spiti, India [70]; Abadeh [71] and Kuh-e-Ali Bashi [72] in Iran; Dorasham [73]; Narmal Nala in Pakistan [74]; Gartner Kofel In Austria [75]; Tesero [76-77] and Sicily [78]; Western United states [79]. In recent years, it was also found in the Canadian Arctic (Henderson, in prep) and Australia and Timor (Nicoll., in prep). Due to its worldwide occurrence, it is acceptable to use the first appearance of Hindeodus parvus as the mark of global basal Triassic. Isarcicella isarcica zone: This zone developed at many sections in South China; Tibet ; Salt Range, Trans-Indus in West Pakistan [80]; Kashmir [67]; Spiti; Iran; Italy; Western USA, Austria; Australia and Canada. It is noteworthy that Dai and Zhang ascribed the element only with one denticle on one side of the oral surface to a new species Isarcicella staeschi [81]. Based on the data from Tesero section, Italy; Xiaoba section, Sichuan Province, and Meishan section [82] in South China, the staeschei occurs earlier than isarcica. Wang [83] and Wang et al.[84] suggests to establish a staeschei zone above the isarcica zone. Clarkina carinata zone: This zone can be recognized in South China; Tibet; Nepal [51]; Kashmir [80, 85]; India; Pakistan; Italy; Nevada, United States and Canada [60]. Neospathodus kummeli zone: This zone has been reported in South China [62, 86-87], Tibet [88], Kashmir; West Pakistan [80], Italy [89], Canada and Australia [61]. Neospathodus dieneri zone: This zone can be recognized in South China; Qinling area, Northwest China [90-91]; Tibet [92]; Nadanhada, Northeast China [93]; Japan [94]; Iran; Pakistan; Spiti, India [95]; Kashimir; Malaysia [96]; Italy; British Columbia; Australia; Svalbard; Spitsbergen [97] ; Canada and Russia [98]. It should be pointed out that the distribution range of dieneri zone seems to partly overlap with that of kumrneli zone and cristagali zone. It has been proved by the data from many areas including Canada [60] and Australia. During the Denerian, however, only the dieneri zone can be recognized at many sections, it is worthy to establish this zone for global correlation. Neospathodus cristagali zone: This zone can be recognized in South China; Tibet; Kashmir; Spiti; Pakistan; Australia; Canada ; Svalbard and United States [44].

376

.

7hejiang, Yunnan ,Guangxi Tibet (Wang et Jiangsu, Auhui, And Guizhou a/.,1976; Yao et Southeast China Southwest a1.,1987; Wang IDing,1992;Tong China (Zhang, et a1.1995; "l'ian, eta/., 1998; 1990; Wang et al., 1982;Zhao et ;'hang et al.1995)t1985; 1990;1995) al., 1991) t ~

c Conodont ~ i_~ Evolutionary ~ Stages and events

v- ~o

'.~ t~o

'

~

Event 7 ~

~

~inling, Qinghai Northwest China ',Lai, 1992; Lai =~tal., 1990;

Nang et a1.,1990) 1996) i I

i

~

: "~ "~ .r~~ ~

t

M. posthersteini

M. posthersteini

M. hersteini

M. hersteini

6~ --

Ep. bidentata

"

international Zonation (Sweet, et al.. 1971; Sweet, 1986; prchard,1983)

Miskella

~ . E v e n t

o

~ladanhada, ~iortheast 3hina (Wang et ~1.,1986; Buryi,

Epigondole//a

i

~

Ep. abneptis

Paragondolella

i

Ep. postera Ep. multidentata

Metapolygnathu,,

-pbidentata Ep. postera

i

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Ep. abneptis

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,-p abneptis

!

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!

i

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i

Ep. multidentata

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=-13.abneptis

!

Ep. bidentata i

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Ep. multidentata ,

I'hisPaper

Ep .postera El:). multidentat

,

Ep. abneptis Mt. nodosus

Og.

oolygnathiformis polygnathiformis

Oolygnathiformis i

o .~

i . Event 5~r --1

.~-

Neogondolella

~"~

!i P a m g o n d o l e / M

.c_

.r-

I-

r

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!

c .~_ .~_

=

i

,

~

t

Dg.polygnathirormis-Gladigondolefla

~g.

Budorovignathu~

~lg.mombergensis

Gladiogondolella

'~lg. constrica ~.Pg. excelsa

Cadnella

Event 4W

Ep. diebeli

~g.

,

' ~ls.newpassensis oolygnathiformis

t

I

excelsa

B..mungoensis

I

I

9.mungoensis

9.mungoensis

Ng.mombergensis ~Ig.mombergensic. Vg.mombergensis ' ~Ig.mombergensis

Ng. bifurcata

~lg. constricta !

Ng. constricta

Ng. regale

Ng. regale

~lg.regale

i

Oolygnathiformis

~

i

i

=

i

' ~s.kockefi

"Vg.consfficata

i

i

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)

~lg.constricata

:

~ls.kockeli i

Vg. regale

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" timorensis

.c:

03

Ng .jubata Neospathodus <~ ' Platyvillosus

.~_ ~

Pachycladina

~ls. homed

Ns .homed

:~ls. tfiangalafis

:Ns. tfiangularis

'

'NS. waageni

e.o

~/s. waageni

I Fumishius !

03

:tVs.conservativus

i

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:Ns. tdangulafis Ng. milled ' Ns. waageni

Ng. jubata

Ng. jubata

Vs. homed

~ls. collinsoni

Ns. homed

i~ls. tfiangularis

~ls. Mangulads ~lg. milled

Ns. triangulads Ng .milled

,

~ls. waageni

INs~

'

'~ ?arachirognathus

~ls.pakistanensis Ns.pakistanensis Vs.pakistanensis I

'

'

'

i

~ls.pakistanensis

i

~ls pakistanensis i

'

Ns. cdstagafi ra

"~

dieneri ~V s. kummeli

'Ns. dieneri

CI. cannata

CI. carinata

CI. cadnata

Event 2.A-

'

.c]~_ Event 3~-

~ ~r~

'

' ,-

=~Hindeodus, ~ Isarcicella 03

L

Event 1 ~

Ns. dieneri

Vs. dieneri

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i

s.cf. diened

~/s. dieneri

i

.~ Ns.kummeli

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,

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i~l. carinata

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~

!

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i

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,

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,

,

,

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,

,

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,

if. isarcica

H. parvus

,

r. isarcica

r isarcica

Fig.2 Triassic conodont zonation, evolutionary stages and their correlation with China. The following abbreviations are used for conodont genera: B.=Budurovignathus, C.-Chisoella,

Cl. -Clarkina, Ep. -Epigondolella, H. -Hindeodus, L -Isarcicella, M. -Misikella, Mr.--Metapolygnathus, Ng.-Neogondolella, ]Vs.-Neospathodus, Pg.-Paragondolella.

377

Neospathodus pakistanensis zone: This zone can be recognized in South China; Northwest China; Tibet; Kashmir; Pakistan; Malaysia; United States; Canada; Svalbard; Australia and Timor. Neospathodus waageni zone: This zone widely spreads in South China; Tibet; Nepal; Malaysia; Kashmir; Spiti, India; Pakistan; Japan; Italy; Russia; Western United Sates; Canada; Australia and Timor. Although the first appearance of waageni is later than that of pakistanensis, it is noteworthy to point out that pakistanensis and waageni commonly occur together in basinal environments [99]. Neogondolella millieri zone: So far, this zone was reported in Tibet; British Columbia; Arctic Canada; Timor [61, 100]; Western United States [101] and N e p a l . In Qinling, Northwest China, one comformis species has been reported [90]. In spite of reputedly irregular occurrence within a Neospathodus waageni zone of broad scope, Orchard et al [60] still consider milleri zone as an index for the late Smithian. It is notable that the PachycladinaParachirognathus assemblage zone dominated in the inner shelf, shallow water facies during Smithian at many areas. For example, at some Smithian shallow water facies in western Guangxi, China [102]; Qinling [90]; Italy [76] there only the PachycladinaParachirognathus zone can be recognized at the same horizon of milleri zone. Neospathodus triangularis zone: This zone or zonal species can be recognized in China; Spiti; Japan; Nepal; Northeast Iran [103]; Bulgaria [104]; Romania; Turkey [105]; Italy [106]; Svalbard; Canada; and West United States. Neospathodus homeri zone: This zone or zonal species can be recognized in South China; Northwest China; Tibet; Kashmir [107]; Spiti; Pakistan; Japan [108]; Italy; Bulgaria; Romania; Russia; Japan; Svalbard; western United States. Generally, homeri can co-occur with triangularis in some sections, so some authors combine both of them as an assemblage zone. However, the first appearance of homeri is later than that of trangularis at many sections. According to the graphic correlation [109], homeri appeared after triangularis. It is worthy to consider homeri as a separate index zone. Because the range of triangularis zone and homeri zone have already covered that of Neospathodus collinsoni, collinsoni zone can be ascribed to above two zones. Neogondolellajubata zone: This zone or zonal species has been reported in Guizhou and Guangxi, Southwest China [110]; Tibet [111]; West Pakistan; Japan; Russia; West United States and Australia. Chiosella (Neospathodus) timorensis zone: This zone can be recognized in South China; Japan; Spiti; Pakistan; Bulgaria; Russia; British Columbia; West United States; Australia; Timor and Canada. Neogondolella regale zone: This zone has widely reported in Southwest China [111-112]; Northwest China; Tibet; Greece; Romania; Turkey; Greenland; British Columbia; West United States [113]; Bulgaria; Timor and Canada. Most previous literatures considered timorensis zone as the top zone of Spathian. Recently, however, Orchard et al. [60] regarded this zone as an Anisian zone.

378

Neospathodus kockeli Zone: This zone or zonal species can be recognized in Southwest China [110,112]; Northeast China [93]; Kashmir [107]; Malaysia; Germany [114]; Bulgaria; Turkey; Austria [44]; Romania; Poland; West United States [115]. The distribution range of kockeli often partly overlaps with that of regale and Neogondolella constricta. However, the first appearance of kockeli is later than that of regale and earlier than that of constricta. This phenomenon can be recognized at many sections from Southwest China [ 112, 116], Bulgaria [ 105] and Russia [ 117]. N. kockeli also often co-occurs with Neospathodus germanicaus and Paragondolella bulgarica, the later two species are often considered as index fossils for the Anisian. Neogondolella constricta zone: This zone widely developed in Southwest China; Qinling; Tibet; Japan; West United States [ 118]; Slovenia [ 119]; Austria and Canada. Neogondolella mombergensis zone: This zone can be recognized in Southwest China; Qinling; Tibet; Northeast China; Spiti; Bulgaria; Germany; West United States and Canada. Some authors [58, 119] adopted Paragondolella excelsa zone instead of mombergensis zone as the first conodont zone of Ladinian. Actually, excelsa already occurred in Anisian and reached to its peak-abundance in Ladinian at many areas. Budurovignathus (Carinella) mungoensis zone: This zone or nominated species can be recognized in Northeast China [93]; Malaysia; Japan; Bulgaria; Italy; Spain; Slovenia; Greece; Hungary; Turkey; Romania; Israel; West United States; Canada and British Columbia. The munogonsis often occurs with Paragondolella foliata which often considered as a nominated species in some areas. Paragondolella polygnathiformis zone: This zone was reported in Southwest China; Tibet; Qinghai, Northwest China [120]; Spiti, India; Japan; Bulgaria; Carpathians [121]; Russia; Timor; Canada and West United States [122]. Metopolygnathus nodosus zone: This zone was reported in Japan; Austria; Sikhole- Alin, Russia [93,117]; Slovenia; Bulgaria; Carpathians; Timor and Canada. Epigondolella abneptis zone: This zone or zonal species can be recognized in western Yunnan, Southwest China [123]; Tibet; Northwest China; Northeast China [124]; Japan; Pokljuka [119]; Austria; Bulgaria; Carpathians; Russia; Greece; British Columbia; West United States. Epigondollea multidentata zone: This zone can be recognized in Tibet; Northeast China; Northwest China; Japan; Austria; Canada; British Columbia and West United States [113, 125]. Epigondolella postera zone: This zone or index species was reported in Tibet, Northwest China; Northeast China; Austria; Bulgaria; Carpathians; Russia; West United States [126]; Canada; Australia and Timor. Epigondolella bidentata zone: This zone can be recognized in Northwest China; Northeast China; Japan; Austria; Bulgaria; Russia; Slovenia [127]; West United States; British Columbia [125]; Canada; Australia and Timor. Misikella hernsteini zone. The Rhaetian conodont data is greatly less than that of preRhaetian. So far, Misikella hernsteini zone can be recognized in China [58]; Japan [108];

379 Australia; Carpathians; Timor; Slovenia and Italy [128]. The chronostratigraphic range of hernsteini zone is still controversial; some authors [57, 108] consider it to be latest Norian. Misikella posthernsteini zone: This zone was recorded in China [58]; Japan [108]; Australia; Carpathians; Italy; Timor and Canada.

3. EVOLUTION OF PERMIAN AND TRIASSIC CONODONTS 3.1. Evolution of Permian conodonts

Five evolutionary stages were recognized for Permian conodonts. They are referred to as in ascending order Stage 1, Stage 2, Stage 3, Stage 4 and Stage 5, and correspond respectively to Asselian and Sakmarian, Lower and Middle Artinskian, Late Artinskian and Kungurian, Guadalupian, and Lopingian in duration (Figure 1). Stage 1 is characterized by Carboniferous-type conodonts such as Streptognathodus and Adetognathus. Stage 2 is characterized by dominance of Sweetognathus whitei and absence of the Carboniferous holdovers and the younger Neostreptognathodus. Stage 3 is represented by Neostreptognathodus, and usually absence of Sweetognathus in Kungurian in cool water provinces and abundance of Sweetognathus and Pseudosweetognathus in the Equatorial Warm Water Province. Stage 4 is represented by Jinogondolella and Sweetognathus in the Equatorial Warm Water Province and Pseudoclarkina and Merrillina in cool water provinces. Stage 5 is characterized by Clarkina and Iranognathus in the Equatorial Warm Water Province, and Pseudoclarkina and Merrillina in the cool water provinces. An exception to this exists where Iranognathus and Clarkina invaded into the Salt Range during the Wuchiapingian, possibly due to global warming in the Wuchiapingian. Four evolutionary events took place among the aforementioned five evolutionary stages. They were well documented in Nashui Section, Luodian, Guizhou and Tieqiao and Penglaitan sections, Laibin, Guangxi. Event 1 was expressed as the disappearance of Carboniferous-type conodonts such as Streptognathodus and Adeptognathus and afterward dominance of Mesogondolella and Sweetognathus. In Nashui section Streptognathodus became extinct in Bed 5, Adeptognathus made its last appearance in Bed 7, and Sweetognathus made its first appearance in Bed 9[55]. Event 2 is characterized by the appearance of Neostreptognathodus and Pseudosweetognathus. In Nashui Section, Neostreptognathodus made its first appearance in Bed 15, and Pseudosweetognathus was found to first appear in Bed 16155]. Event 3 is marked by the replacement of Mesogondolella by Jinogondolella in Equatorial Warm Water Province and by Pseudoclarkina in cool water provinces. This event was recognized at the base of Bed 42 in Nashui Section, and between Bed 111 and Bed 112 in Tieqiao Section. Event 4 is represented by replacement of Jinogondolella and Sweetognathus by Clarkina and Iranognathus respectively. In Tieqiao Section, this event was recognized in the topmost of Bed 119 [34]. Two patterns of evolution were recognized for the two most important conodont crises in the Permian. One is referred to as the Substitution Pattern, which is exemplified by Event 4,

380 or the pre-Lopingian Benthos Crsis [129-130]. It is characterized by the abrupt substitution of Jinogondolella and Sweetognathus by Clarkina and Iranognathus respectively. In this case, the survival interval between the extinction and the recovery intervals is extremely short. The other is referred to as the Extinction-Survival-Recovery Pattern, which is exemplified by the other conodont crisis, the so called Early Permian conodont crisis, which includes Event 1 and Event 2 and is represented also by a distinct survival interval dominated by Sweetognathus and Mesogondolella in Artinskian between the extinction interval in which the Carboniferoustype conodonts such as Streptognathodus and Adetognathus become extinct towards the end of Sakmarian and the recovery interval where Neostreptognathodus first appears in the Artinskian. It is noteworthy that the Substitution Pattern was associated with a strong development of provincialism and the Extinction-Survival-Recovery Pattern seems to occur during intervals when provincial control is not so strong. 3.2. Evolution of end-Permian and earliest Triassic conodonts

Since Yin et al. [ 131 ] suggested the first appearance of the conodont Hindeodus parvus as the base of the global Triassic, this proposal has been accepted by more and more paleontologists around the world. Hence, the end-Permian and earliest Triassic conodonts received intensive study at numerous Permian - Triassic (P/T) boundary sections in the world, and its resolution is higher than any periods of the Permian and Triassic. Because there were many events including volcanism, anoxia, sea level changes, paleomagnetic polarity changes and possible impact events that took place at the Paleozoic-Mesozoic transition [132], conodonts were inevitably influenced by these events, it constitutes the evolution Event 1 of Triassic which was expressed by the decline of Clarkina stock at many areas.. Generally, it seems that Clarkina was replaced by Hindeodus after the P/T transitional period in many areas including South China, Iran, Salt Range, Europe, and the Western United States. However, the basal Triassic was still dominated by Clarkina in Selong, Tibet [66], Spiti, India [70] and Canadian Arctic [60, 133]. The above data do not support that Clarkina was replaced by Hindeodus at end-Permian and earliest Triassic in a worldwide evolving tendency. At Meishan section, Zhejiang province, China, such replacement coincided with a revealed anoxic event during the end-Permian and earliest Triassic [ 134]. Lai et a/.[135-136] proposed that Hindeodus was a pelagic type found in different depth environment, and because it lived in the top layer of the water, it could survive although there was anoxia in the deeper water. Lai believes that Clarkina was a free-swimming genus, which often occurred in offshore, deeper and oxygen-rich environments, and declined as anoxic conditions developed in the deeper bottom waters of the P/T transitional period, but can be recognized in the oxygen-rich environments or areas during the end-Permian and earliest Triassic. Matsuda [45] and Mei [5,46] pointed out that this difference in distribution of Hindeodus and Clarkina around the Permian-Triassic boundary interval may be due to conodont provincialism. Due to the recent accumulation of large amounts of conodont data during the end-Permian and earliest Triassic, there are many recent papers that dealt with the conodont lineage near

381 the P/T Boundary. Kozur [57] first proposed the phylomorphogenetic line of Hindeodus typicalis- H. latidentadus - H. turgidus- Isarcicella isarcica. Ding et al. [137-138] established the same lineage of H. latidentadus - H. parvus - Isarcicella turgida (H. turgidus) - I. isarcica at Meishan. Wang [83] suggested H. latidentatus- H. parvus Morphotype 1- I. staeschei- L isarcica lineage instead of latidentatus-parvus- turgida- isarcica. Tian [139] and Mei [46] considered that H. parvus evolved from H. typicalis. Mei [46] also pointed out that H. latidentadus was named basing on a poorly preserved and probably juvenile specimen. Kozur [57], Ding et al. [137] , Wang[ [83] and Lai [82] preferred that H. parvus evolved from H. latidentatus. Morphologically, latidentatus is more closer to parvus than to typicalis. Stratigraphically, the first appearance of latidentatus is lower than parvus, and these two species can co-occur at the basal Triassic parvus zone. In Meishan, latidentatus occurs at bed 25 (white clay) near the top of the Upper Permian [63, 140], and co-occurs with parvus at bed 27c [141]. In NW Iran [142], Dorasham [143], Armenia [73], Austria [144], the same conclusion can be reached. That Isarcicella isarcica evolved from H. parvus is an accepted idea [57,83, 137-139,145146]. The main discrepancy is whether there existed a transitional form between parvus and isarcica, and what is the intermediate form. Tian [139] and Wang et al. [146] consider that isarcica directly evolved from parvus. Kozur [57, 145] and Ding et al.[137-138] suppose that Isarcicella turgida is the transitional form between parvus and isarcica. Morphologically,/. turgida has a transverse ridge on the sides of its upper surface, so it is acceptable that it evolved to laterally denticulate isarcica. Stratigraphically, I. turgida occurs earlier than parvus in Hambast C, Abadeh [ 71], NW Iran [142] and Gartnerkofel [75]. These data support that/. turgida evolved from H. parvus. On the other hand, turgida occurs earlier than parvus in Shangsi [81,147]. Even in Meishan, the first appearance of H. parvus [141,148] and that of L turgida located at the same horizon bed 27c [141,148-149]. It is difficult to confirm I. turgida evolved from H. parvus in Shangsi and Meishan. Therefore, the main problem of cline parvus - turgida- isarcica is the relative stratigraphical range between parvus and turgida. 3.3.

Evolution of Triassic conodonts

So far, at least six major evolutionary stages can be recognized for Triassic conodonts. They are referred to as in ascending order as Stage 1, Stage 2, Stage 3, Stage 4, Stage 5 and Stage 6, and correspond respectively to early and middle Griesbachian, late Griesbachian, Dienerian to Spathian, Middle Triassic, Carnian to Norian and Rhaetian. Stage 1 is characterized by existence of Hindeodus and Isarcicella. In most areas including South China, Tethys, United States, this stage is dominated by Hindeodus and Isarcicella; In Kashimir, Canadian Arctic it is dominated by Clarkina and contained few Hindeodus and Isarcicella. Stage 2 is represented by dominance of Clarkina carinata and absence of the older Hindeodus, Isarcicella and younger Neospathodus. Stage 3 is characterized by the dominance of Neospathodus and fewer Neogondolella, Platyvilosus. It is noteworthy that abundant shallow water genera including abundant Parachirognathus, Pachycladina and Furnishius developed in this stage especially in Smithian. Stage 4 is characterized by dominance of neogondolellid

382 conodonts including Neogondolella, Paragondolella , Budurovignathus, Carinella, Gladigondolella, and with some survivors of Neospathodus and forerunners of Epigondolella. The conodont diversity in Stage 4 was relatively higher compared to other periods in the Triassic; it constituted the last peak-abundance of conodonts. Stage 5 is dominated by Epigondolella, Metapolygnathus and some survivors of Paragondolella. As the accumulation of Triassic conodont data, Buryi [93,150] discussed the evolution of Late Triassic conodont platform elements and considered Paragondolella , Metapolygnathus and Epigondolella originated from the same root- Neogondolella. Stage 6 is characterized by the dominance of the small-type conodont Misikella and fewer survivors of Epigondolella. The conodont diversity and abundance is greatly diminished during this stage and there is little conodont data from this stage reported in the world. Besides the P/T transitional period crisis lead to the Event 1 which is discussed above, six evolutionary events can be distinguished among above six evolutionary stages in Triassic (Fig.2). Event 2 was declared by the disappearance of Hindeodus and Isarcicella and the dominance of Clarkina carinata. Event 3 was expressed by first appearance of Neo~pathodus. Event 4 was expressed by the decline of Neospathodus and especially the flourishing of Neogondolella stock. Event 5 was expressed by the first appearance of Paragondolella polygnathifrmis and afterward dominance of Epigondolella. Event 6 was represented by the first emergence of Misikella and absence of other kinds of conodonts. Event 7 was marked by the extinction of the conodont. Conodonts ended their nearly 400Ma -long evolutionary history at the end of Triassic. It is still not uncertain about which kind of "bad luck" leads to the conodont extinction. Clark [151] proposed that the conodont extinction related to the worldwide sea level falling during the Triassic and Jurassic transitional period. However, it is hard to explain the phenomenon that conodonts survived through many immense paleoenvironmental changes including that of the P/T transitional period. Most probably, the main factor of conodont extinction is related to evolution of itself, especially its high evolutionary rate during the Triassic. It seems evolution of Triassic conodonts is dominated by an Extinction- SurvivalRecovery evolution pattern. For example, the Late Griesbachian conodont crisis, which is characterized by a distinct survival interval dominated by Clarkina carinata between the interval characterized by the extinction of Hindeodus and Isarcicella and the recovery interval in which Neospathodus first appears. On a broad scope, the neogondolellid conodont Clarkina dominated in the Late Permian, between the Late Permian and Middle Triassic which characterized by the abundance of neogondolillid conodonts Neogondolella and Paragondolella is the interval of Lower Triassic which characterized the development of Hindeodus, Isarcicella, Neospathodus, Pachycladina, Parachirognathus. The ExtinctionSurvival- Recovery evolution pattern of Triassic neogondolillid conodonts coincides with that of other taxa, including bivalvia, brachipods, ammonites, corals and algae.

383

4. A C K N O W L E D G M E N T S Authors thank the financial support from the National Natural Science Foundation of China (grant No. 49632070). Mei Shilong acknowledges support from the Ministry of Land and Resources. Thanks are also due to Professor Yin Hongfu for his valuable c o m m e n t s on this manuscript draft.

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