Palygorskite-Sepiolite: Occurrences, Genesis and Uses (Developments in Sedimentology)

DEVELOPMENTS IN SEDIMENTOLOGY 37

PACYGORSKITE - SEPlOllTE Occurrences, Genesis and Uses

FURTHER TITLES IN THIS SERIES VOLUMES 1.2.3.5.8 and 9 are out of print 4 F.G. T I C K E L L THE TECHNIQUES O F SEDIMENTARY MINERALOGY 6 L. V A N D E R PLAS T H E IDENTIFICATION O F DETRITAL FELDSPARS 7 S. D Z U L Y N S K I and E.K. W A L T O N SEDIMENTARY FEATURES O F FLYSCH AND GREYWACKES 10 P.McL.D. D U F F , A. H A L L A M and E.K. W A L T O N CYCLIC SEDIMENTATION 11 C.C. REEVE'S Jr. INTRODUCTION T O PALEOLIMNOLOGY 12 R.G.C. B A T H U R S T CARBONATE SEDIMENTS AND THEIR DIAGENESIS 13 A.A. M A N T E N SILURIAN R E E F S O F GOTLAND 14 K.W. G L E N N I E DESERT SEDIMENTARY ENVIRONMENTS 1 5 C.E. W E A V E R and L.D. P O L L A R D THE CHEMISTRY O F CLAY MINERALS 16 H.H. R I E K E III and G . V . C H I L I N G A R I A N COMPACTION O F ARGILLACEOUS SEDIMENTS 11 M.D. P I C A R D and L.R. HIGH Jr. SEDIMENTARY STRUCTURES O F EPHEMERAL STREAMS 18 G . V . C H I L I N G A R I A N and K.H. W O L F , Editors COMPACTION O F COARSE-GRAINED SEDIMENTS 19 W. S C H W A R Z A C H E R SEDIMENTATION MODELS AND QUANTITATIVE STRATIGRAPHY 20 M.R. W A L T E R , E d i t o r STROMATOLITES 21 B. V E L D E CLAYS AND CLAY MINERALS I N NATURAL AND SYNTHETIC SYSTEMS 22 C.E. W E A V E R and K.C. B E C K MIOCENE O F THE SOUTHEASTERN UNITED STATES 23 B.C. H E E Z E N , Editor INFLUENCE O F ABYSSAL CIRCULATION O N SEDIMENTARY ACCUMULATIONS IN SPACE AND TIME 24 R.E. G R I M and G U V E N BENTONITES 25A G. L A R S E N and G . V . C H I L I N G A R , Editors DIAGENESIS I N SEDIMENTS AND SEDIMENTARY ROCKS, I 26 T.S U D O and S. S H I M O D A , Editors CLAYS AND CLAY MINERALS O F JAPAN 21 M.M. M O R T L A N D and V.C. F A R M E R , Editors INTERNATIONAL CLAY CONFERENCE 1978 28 A . N I S S E N B A U M , Editor HYPERSALINE BRINES AND EVAPORITIC ENVIRONMENTS 29 P. T U R N E R CONTINENTAL R E D BEDS 30 J . R . L . A L L E N SEDIMENTARY STRUCTURES 31 T.S U D O , S. S H I M O D A , H . Y O T S U M O T O and S . A I T A ELECTRON MICROGRAPHS OF CLAY MINERALS 32 C.A. N I T T R O U E R , E d i t o r SEDIMENTARY DYNAMICS O F CONTINENTAL SHELVES 33 G.N. B A T U R I N PHOSPHORITES ON THE SEA FLOOR 34 J.J. F R I P I A T . E d i t o r ADVANCED TECHNIQUES F O R CLAY MINERAL ANALYSIS 36 H . V A N O L P H E N and F . V E N I A L E , Editors INTERNATIONAL CLAY CONFERENCE 1981 36 A. I I J I M A , J.R. H E I N and R. S I E V E R . E d i t o r s SILICEOUS DEPOSITS IN T H E PACIFIC REGION

DEVELOPMENTS IN SEDIMENTOLOGY 37

PALYGORSKITE - SEPlOLlTE Occurrences, Genesis and Uses Edited by

A. SINGER The Hebrew University o f Jerusalem, Seagram Centre f o r Soil & Water Sciences, Rehovot 76-100 (Israel) and

E. GALAN Departamento de Geologia, Facultad de Quimica, Palos de la Frontera 1, Universidad d e Sevilla, Sevilla (Spain)

ELSEVIER Amsterdam - Oxford -New York - Tokyo

1984

ELSEVIER SCIENCE PUBLISHERS B.V. Molenwerf 1 P.O. Box 211,1000 AE Amsterdam, The Netherlands Distributors for the United States and Canada: ELSEVIER SCIENCE PUBLISHING COMPANY INC. 52, Vanderbilt Avenue New York, N.Y. 10017

Library of Congress Cataloging i n Publication D a t a

Main e n t r y under t i t l e : P a l y g o r s k i t e - s e p i o l i t e occuri-CLICC - , pcni.7 i s , ;Ind

URII;.

(Dtvelopments i n s e d i m e n t o l o a ; 37) Bibliosraphy: p. Includcs indexes. 1. P a l y g o r s k i t e . 2. Meerschau?:. I . Singer, A. 11. Galan, E. III. S e r i e s . $E391.P34P34 1gL4 >JI~ .I> ' ;4-59,7 ISBN 0-444-4;337-0

ISBN 0-444-42337-0 (Vol. 37) ISBN 0-444-41238-7 (Series) Elsevier Science Publishers B.V., 1984 All rights reserved. N o part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording o r otherwise, without the prior written permission of the publisher, Elsevier Science Publishers B.V., P.O. Box 330, 1000 AH Amsterdam, The Netherlands 0

Printed in The Netherlands

V PREFACE The p a l y g o r s k i t e - s e p i o l i t e c l a y m i n e r a l group, a l s o known as t h e h o r m i t e group, f i b r o u s c l a y m i n e r a l s , o r c h a i n p h y l l o s i l i c a t e s , has r e c e i v e d f a r l e s s a t t e n t i o n than o t h e r major c l a y minerals.

This neglect p a r t l y

r e f l e c t s t h e f a c t t h a t t h e s e c l a y m i n e r a l s a r e l e s s common t h a n t h e l a y e r phyllosilicates.

D i f f i c u l t i e s i n i d e n t i f i c a t i o n , p a r t i c u l a r l y during rou-

t i n e XRD i d e n t i f i c a t i o n procedures f o r g e o l o g i c a l surveys, may a l s o have c o n t r i b u t e d t o t h e s c a r c i t y o f i n f o r m a t i o n a v a i l a b l e on t h i s c l a y m i n e r a l group. D e s p i t e t h i s , however, t h e p a l y g o r s k i t e - s e p i o l i t e c l a y group has been known t o , and used by mankind f o r c e n t u r i e s because o f i t s many d i v e r s e and u s e f u l p r o p e r t i e s , and makes i n t e r e s t i n g h i s t o r y .

Pre-Columbian I n d i a n s

f r o m t h e Yucatan p e n i n s u l a c a l l e d p a l y g o r s k i t e c l a y "Sac l u ' u m " (Maya f o r "White E a r t h " ) and used i t i n t h e p r o d u c t i o n o f ceramics, as f a r back as

800 y e a r s ago.

When mixed w i t h i n d i g o i t produced t h e h i g h l y p r i z e d o r g a -

n i c pigment known as "Maya B l u e " .

" T i e r r a del Vino", a mixture o f c a l c i t e

and s e p i o l i t e has been used f o r t h e p u r i f i c a t i o n o f w i n e i n L e b r i j a , a p r o v i n c e o f Spain, f o r hundreds o f y e a r s and s e p i o l i t e , mined i n Spain s i n c e t h e b e g i n n i n g o f t h e 1 7 t h C e n t u r y i s used i n t h e manufacture o f p i p e s and c i g a r e t t e f i l t e r s , and was a l s o used f o r c e r a m i c s d u r i n g t h e l a t e 1 9 t h Century. These c l a y s today, because o f t h e i r c o l l o i d a l - r h e o l o g i c a l p r o p e r t i e s , have a wide range o f i n d u s t r i a l a p p l i c a t i o n s and a r e c o n s i d e r e d t o be one o f t h e most i n t e r e s t i n g m i n e r a l groups used i n i n d u s t r y . Many new o c c u r r e n c e s o f c h a i n - p h y l l o s i l i c a t e s ,

p a r t i c u l a r l y palygorskite,

which i s more abundant t h a n s e p i o l i t e , have been r e p o r t e d d u r i n g t h e p a s t few y e a r s and l a r g e amounts o f i n f o r m a t i o n on t h e i r e n v i r o n m e n t a l c h a r a c t e r i s t i c s have r e s u l t e d .

The l a b o r a t o r y s y n t h e s i s o f c h a i n p h y l l o s i l i c a t e s under con-

t r o l l e d c o n d i t i o n s , however, has encountered d i f f i c u l t i e s and t h e r e s u l t i n g hypotheses on t h e g e n e s i s o f t h e s e c l a y s a r e t h e r e f o r e f a i r l y s p e c u l a t i v e . I n a d d i t i o n , r e p o r t s on p a l y g o r s k i t e - s e p i o l i t e occurrences a r e w i d e l y d i s s e m i -

VI n a t e d t h r o u g h o u t t h e many e a r t h - s c i e n c e d i s c i p l i n e s of geology, m i n e r a l o g y , s o i l s c i e n c e and oceanography.

I t i s t h e r e f o r e a p p a r e n t t h a t a comprehensive

r e v i e w i s l o n g overdue.

I n response t o t h e i n i t i a t i v e o f one o f t h e e d i t o r s , a symposium e n t i t l e d "Occurrences and Genesis o f S e p i o l i t e / P a l y g o r s k i t e Sediments" was o r g a n i z e d d u r i n g t h e 7 t h I n t e r n a t i o n a l C l a y Conference, h e l d i n I t a l y i n 1981.

Nine

papers were p r e s e n t e d a t t h i s sympsoium and i n a d d i t i o n , s i n c e t h e o r g a n i z e r s f e l t t h a t t h i s s u b j e c t deserved more comprehensive monographic coverage, cont r i b u t i o n s f r o m well-known s p e c i a l i s t s i n t h i s f i e l d were s o l i c i t e d .

The

r e s u l t i n g volume, which i n c l u d e s e i g h t o f t h e papers p r e s e n t e d a t t h e I n t e r n a t i o n a l Clay Conference, i s t h e outcome o f t h i s i n i t i a t i v e . F o l l o w i n g an i n t r o d u c t i o n on t h e d i s t r i b u t i o n o f p a l y g o r s k i t e i n space and t i m e , t h e c o n t r i b u t i o n s a r e a r r a n g e d a c c o r d i n g t o t h e t y p e s o f e n v i r o n ment a s s o c i a t e d w i t h t h e o c c u r r e n c e s .

These i n c l u d e c o n t i n e n t a l ( s u b d i v i d e d

i n t o l a c u s t r i n e and pedogenic) and p e r i m a r i n e environments.

The hydrothermal

environment i s r e p r e s e n t e d by o n l y one c o n t r i b u t i o n f r o m Japan, and one sect i o n i n c l u d e s n o t e s on d e p o s i t s f r o m U.S.S.R.,

o f China.

I n d i a and t h e P e o p l e ' s R e p u b l i c

The volume c l o s e s w i t h a d i s c u s s i o n on t h e i n d u s t r i a l a p p l i c a t i o n s

o f p a l y g o r s k i t e - s e p i o l i t e minerals.

Two appendices i n c l u d e d e t a i l s o f DSDP

occurrences o f t h e s e m i n e r a l s , i n a d d i t i o n t o a c o m p l e t e l y u p - t o - d a t e b i b 1 i o graphy.

The r e v i e w e d and e d i t e d m a n u s c r i p t s were t y p e d by t h e a u t h o r s i n

camera-ready f o r m and t h e volume was produced by p h o t o - o f f s e t . due t o t h e a u t h o r s and r e v i e w e r s .

A. S i n g e r , E. Galan Editors

Thanks a r e

VII

TABLE OF CONTENTS

v

PREFACE INTRODUCTION: DISTRIBUTION OF PALYGORSKITE-SEPIOLITE IN SPACE AND TIME

Clays of the palygorskite-sepiolite group: depositional environment, age and distribution 1 R.A. CALLEN,' SECTION I.

DEPOSITS IN PERI-MARINE ENVIRONMENTS

Origin and geologic implications of the palygorskite of the S.E. United States 39 C.E. WEAVER The clays of Yucatan, Mexico: a contrast in genesis W.C. 1SPHORDING

59

Palygorskite in the Tertiary deposits of the Armorican Massif J. ESTEOULE-CHOUX

75

SECTION 11.

DEPOSITS AND OCCURRENCES IN CONTINENTAL ENVIRONMENTS: LACUSTRINE

Sepiolite-palygorskite in Spanish Tertiary Basins: genetical patterns in continental environments E. GALAN AND A. CASTILLO

87

Sepiolite in the Amboseli Basin of Kenya: a new interpretation 125 R.L. HAY AND R.K. STOESSEL Sepiolite in Pleistocene Lake Tecopa, Inyo County, California H.C. STARKEY AND P.D. BLALKMON

137

Diagenetic palygorskite in marginal continental detrital deposits located in the south of the Tertiary Duero Basin (Segovia, Spain) S. LEGUEY, J. MARTIN DE VIDALES AND J. CASAS 149 Ballarat sepiolite, Inyo County, California J.L. POST AND C . JANKE SECTION 111.

159

DEPOSITS AND OCCURRENCES IN CONTINENTAL ENVIRONMENTS: PEDOGEPTIC

Pedogenic palygorskite in the arid environment A. SINGER

169

Origin of palygorskite in some soils of the Arabian Peninsula R.C. MACKENZIE, M.J. WILSON AND A.S. MASHHADY

177

Occurrence of palygorskite in the soils and rocks of the Jordan Valley H. SHADFAN AND J.B. DIXON 187 Occurrence of palygorskite in ground-water rendzinas (Petrocalcic Calciaquolls) in south-east South Australia T. HODGE, L.W. TURCHENEK AND J.M. OADES

199

VIII

SECTION I V . DEPOSITS AND OCCURRENCES I N CONTINENTAL ENVIRONMENTS: HYDROTHERMAL S e p i o l i t e and p a l y g o r s k i t e i n Ja p a n N. IMAI AND R. OTSUKA SECTION V.

21 1

NOTES ON THE OCCURRENCES AND USES OF PALYGORSKITESEPIOLITE I N THE USSR, I N D I A AND P.R. OF C H I N A

P a l y g o r s k i t e and s e p i o l i t e d e p o s i t s i n t h e USSR and t h e i r u s e s P.D. OVCHARENKO AND Y E . G . KUKOVSKY

233

O c c u r r e n c e of p a l y g o r s k i t e i n t h e Deccan T r a p F o r m a t i o n i n I n d i a M . K . HASNUDDIN SIDDIQUI

243

S e p i o l i t e c l a y d e p o s i t s i n South China ZHANG R E N J U N

25 1

SECTION V I .

INDUSTRIAL USES OF SEPIOLITE

S e p i o l i t e : p r o p e r t i e s and u s e s A. ALVAREZ SECTION V I I .

253

APPENDICES

A p p e n d i x I , 1-3: D e t a i l s of Deep Sea D r i l l i n g P r o j e c t o c c u r r e n c e s ; 4: Details of l a n d o c c u r r e i c e s R . CALLEN, c o m p i l e r 289 Appendix 11: B i b l i o g r a p h y R. CALLEN, c o m p i l e r

315

AUTHOR I N D E X

337

SUBJECT I N D E X

339

1

CLAYS O F THE PALYGORSKITE-SEPIOLITE GROUP: DEPOSITIONAL ENVIRONMENT, AGE AND DISTRIBUTION*

ROGER A. CALLEN Eastwood, S.A.

Department of Mines and Energy, South A u s t r a l i a ,

Box 151,

5063.

ABSTRACT Major d e p o s i t s of p a l y g o r s k i t e - s e p i o l i t e

g r o u p m i n e r a l s were i n i t i a l l y

formed i n t h r e e e n v i r o n m e n t s of d i f f e r e n t c h a r a c t e r

-

( 1 ) i n epicontinental

and i n l a n d seas and l a k e s as c h e m i c a l s e d i m e n t s , o r by r e c o n s t i t u t i o n of former c l a y s d u r i n g e a r l y d i a g e n e s i s ;

( 2 ) i n t h e open o c e a n s i n a s s o c i a t i o n

w i t h f o r e - a r c b a s i n s and ocean rises by h y d r o t h e r m a l a l t e r a t i o n of b a s a l t i c q l a s s , v o l c a n i c s e d i m e n t s or c l a y s ;

( 3 ) i n c a l c a r e o u s s o i l s by d i r e c t

S u b s e q u e n t l y marine d e p o s i t s w e r e a l s o formed by slumping

crystallization.

and t u r b i d i t y c u r r e n t t r a n s p o r t of n e a r s h o r e m a t e r i a l s ,

and from windblown

dust. Palygorskite-sepiolite

group m i n e r a l s which formed i n s o i l s , l a k e s or

s h a l l o w seas w e r e m o s t l y a s s o c i a t e d w i t h a M e d i t e r r a n e a n t o s e m i - a r i d

climate.

T h i s i s r e f l e c t e d i n t h e i r d i s t r i b u t i o n i n low l a t i t u d e s .

These

climatic c o n d i t i o n s were p r e s e n t d u r i n g t h e L a t e Devonian and C a r b o n i f e r o u s and L a t e Permian t o T r i a s s i c i n t h e n o r t h e r n h e m i s p h e r e , and i n t h e E a r l y and

L a t e Eocene, L a t e O l i g o c e n e and l a t e Neogene, and p o s s i b l y Late C r e t a c e o u s i n b o t h hemispheres. marine o r i g i n .

The L a t e C r e t a c e o u s d e p o s i t s are l a r g e l y of h y d r o t h e r m a l

Some of t h e Devonian d e p o s i t s a r e a s s o c i a t e d w i t h b a s a l t s , and

t h e i r mode of o c c u r r e n c e s u g g e s t s t h e y may be h y d r o t h e r m a l o c e a n i c t y p e s . These c o n c l u s i o n s were r e a c h e d by e x a m i n i n g P l i o - P l e i s t o c e n e distributions,

l i t h o f a c i e s a s s o c i a t e s and occurrence d i s t r i b u t i o n s , p l o t t e d on

p a l a e o c o n t i n e n t a l maps.

when the o r i g i n a l d i s t r i b u t i o n - b i a s i n DSDP d a t a

( c o i n c i d e n t a l l y i n similar l a t i t u d e s to c o n t i n e n t a l d a t a ) w a s e l i m i n a t e d , t h e r e was l i t t l e e v i d e n c e f o r l a t i t u d i n a l c o n c e n t r a t i o n i n t h e oceans. Sampling b i a s on l a n d is d i f f i c u l t to assess, b u t t h e r e a p p e a r s t o be a c o n c e n t r a t i o n between 30° and 40° N and S . between 20°-400N

and 10°-350S

There is a d i s t i n c t concentration

i n t h e l a t e Neogene,

f o r b o t h l a n d and sea

deposits.

*Presented at the International Clay Conference 1981.

2 M TRODUCTI (El The p a l y g o r s k i t e - s e p i o l i t e ( p a l y g o r s k i t e o r a t t a p u l q i te,

etc.

-

g r o u p m i n e r a l s o r f i b r o u s magnesium c l a y s

s e p i o l ite, p i l o l i te, l o u g h l i n i te, f r a n c l a n d i te,

h e n c e f o r t h r e f e r r e d to as p a l y g o r s k i t e s ) were once r e g a r d e d as rare

m i n e r a l s , r e s t r i c t e d t o h y d r o t h e r m a l v e i n s and ore-body a l t e r a t i o n z o n e s . They are now known to be widespread i n marine and non-marine e s p e c i a l l y i n t h e oceans.

s e d i m e n t s , and

The p a l y q o r s k i t e s are s t r o n g l y a b s o r b e n t , v e r y

l i g h t , and p o r o u s , which makes them much sough+ a f t e r as F u l l e r ' s E a r t h , meerschaum and s i m i l a r materials, f o r i i d u s t r i a l a b s o r b a n t s , c a t a l y s t s and

ceramics.

S t r u c t u r e and c o m p o s i t i o n are summarized i n Zelazny and Calhoun

( 1 9 7 7 ) who g i v e a d e q u a t e r e f e r e n c e s of d e t a i l e d s t r u c t u r a l s t u d i e s . The g e o l o g y of t h e s e c l a y s h a s s u g g e s t e d t h e y c o u l d b e good p a l a e o c l i m a t i c i n d i c a t o r s (e.g.

Weaver and Beck,

1977, M i l l o t ,

1964, Wiersma,

1970, S i n g e r , 1979, 1980. 1981, Chamley, 1979, Chamley e t a l , 1977, LOmova, 1979, among o t h e r s ) .

Hence a n e a r l i e r c o n t r i b u t i o n o f C a l l e n ( 1 9 7 7 ) h a s been

e x t e n d e d t o i n c l u d e t h e l a r g e amount of Deep Sea D r i l l i n g P r o j e c t (DSDP)

material, and many new i n v e s t i g a t i o n s of l a n d d e p o s i t s .

METHODS The l i t h o l o g i c a l a s s o c i a t i o n of each d e p o s i t w a s r e c o r d e d , and t h e l o c a t i o n p l o t t e d on p a l a e o c o n t i n e n t a l maps.

For t h e o l d e r d e p o s i t s ,

E c k e r t p r o j e c t i o n s of Kanasewich e t a1 (1978) are used ( F i g . 4 ) .

the

a s it i s

easier t o p l o t on t h e s e , and t h e y show t h e d i s t r i b u t i o n of l a n d and s h e l f sea.

More recent p a l a e o c o n t i n e n t a l maps, u s i n g s e d i m e n t a r y palaeoclimatic

i n d i c a t o r s i n a d d i t i o n t o i n d e p e n d e n t p a l a e o m a g n e t i c d a t a , have been p r e p a r e d by Z i e g l e r e t a l . ( 1 9 7 9 ) .

The l a t t e r place Devonian European R u s s i a j u s t

n o r t h of t h e e q u a t o r and C a r b o n i f e r o u s R u s s i a f u r t h e r s o u t h t h a n t h e maps o f Kanasewitch e t al. (19781, b o t h b e i n g i m p o r t a n t areas and t i m e s of palygorskite deposition. For o c e a n i c o c c u r r e n c e s the polar p r o j e c t i o n r e c o n s t r u c t i o n s of Firstbrook et al.

( 1 9 7 9 ) are used ( F i g s . 5-9).

They have t h e a d v a n t a g e o f

b e i n g a t 10 Ma i n t e r v a l s , w i t h DSDP h o l e s p l o t t e d .

They are similar t o t h e

Smith and Briden ( 1 9 8 0 ) maps w i t h respect to c o n t i n e n t a l p o s i t i o n s .

The S m i t h

and B r i d e n mercator p r o j e c t i o n s are u s e d t o p l o t c o n t i n e n t a l p a l y g o r s k i t e s and

summarize oceanic occurrences ( F i g s . 1 , 4 , 1 0 - 1 2 ) , view o f l a t i t u d i n a l d i s t r i b u t i o n , well-defined

because they g i v e a b e t t e r

and the a g e of land-based

t h a t narrower t i m e i n t e r v a l s can be c o n s i d e r e d .

d e p o s i t s is n o t so

3 The comments of S c o t e s e ( 1 980) concerning a l t e r n a t i v e c o n t i n e n t a l c o n f i g u r a t i o n s must be c o n s i d e r e d with respect to t h e r e c o n s t r u c t i o n s of Smith and Briden (1980) and F i r s t b r o o k e t a1 ( 1 9 7 9 ) .

The p o s i t i o n of N e w Zealand on

t h e Mercator p r o j e c t i o n s h a s been a d j u s t e d a p p r o x i m a t e l y , i n l i n e with t h e s u g g e s t i o n s of Scotese ( 1 9 8 0 ) . reconstructions.

Smith (1981) h a s r e c e n t l y updated some of h i s

The work o f Veevers e t a l . (1980) s u g g e s t s a somewhat

d i f f e r e n t h i s t o r y f o r t h e s o u t h e r n I n d i a n Ocean and t h e p o s i t i o n of It i s s u g g e s t e d t h a t Madagascar w a s a t t a c h e d to A u s t r a l i a ,

Madagascar.

r e a c h i n g a ?re

n o rth erl y l o cat io n a t an e a r l y stage.

Basically, these

a d j u s t m e n t s make no major changes i n t h e d i s t r i b u t i o n p a t t e r n s ( F i g s . 5-6). D a t a f o r DSDP c r u i s e s and onshore s t u d i e s has been o b t a i n e d from t h e

p r o j e c t volumes (see r e f e r e n c e s ) , though t h e r e are some i m p o r t a n t a d d i t i o n a l a n a l y s e s p u b l i s h e d e l s e w h e r e (Appendix 1.1 and r e f e r e n c e s ) .

The d a t a used are

e s s e n t i a l l y t h a t of o r i e n t e d < 2 ~ )c l a y a n a l y s e s ; o t h e r u n o r i e n t e d < 2 ~ )a n a l y s e s a r e recorded and p l o t t e d b u t n o t used i n t h e p e r c e n t a g e c a l c u l a t i o n s .

A few

p a p e r s p u b l i s h e d o u t s i d e t h e DSDP series, b u t u s i n g t h e p r o j e c t cores, do n o t

state t h e a n a l y t i c a l method, b u t i t is assumed t h e s e are o r i e n t e d

(211) samples.

D a t a from t h e South A t l a n t i c Ocean and 1982 onwards has n o t y e t

been i n c o r p o r a t e d i n t h e p e r c e n t a g e abundance s t u d i e s , p a r t l y due t o l a c k of s u f f i c i e n t d e t a i l i n some r e p o r t s . D a t a from DSDP s t u d i e s were s u f f i c i e n t t o r e c o r d t h e approximate

abundance o f p a l y g o r s k i t e p l u s s e p i o l i t e ( F i g s . 2-6) i n each h o l e f o r each 10 My t i m e s l i c e .

The scheme used t o show this on t h e polar p l o t s i s e s s e n t i a l l y

q u a l i t a t i v e , and i s e x p l a i n e d i n t h e f i g u r e c a p t i o n . %

A l l t h e d a t a used i n t h e

abundance and a v e r a g e c a l c u l a t i o n s ( F i g . 1 3 and Appendix 1.2) are t a b u l a t e d

(Appendix 1 . 3 i n c l u d e s a d d i t i o n a l d a t a o b t a i n e d s i n c e these c a l c u l a t i o n s w e r e made

.

PREVIOUS WORK M o s t s i g n i f i c a n t p r e v i o u s work is summarized and a d e q u a t e l y d i s c u s s e d i n

t h e reviews by S i n g e r (1979, 19801, Weaver and Beck (1977) and Lomova ( 1 9 7 9 ) . S i n g e r (1980) concluded that p a l y g o r s k i t e s a r e t y p i c a l of a r i d and s e m i a r i d s o i l s , and one of t h e few u s e f u l palaeoclimatic i n d i c a t o r s among t h e c l a y minerals.

S i n g e r (1979) also s p e c i f i e d the c o n d i t i o n s of f o r m a t i o n of

p a l y g o r s k i t e and s e p i o l i t e , b e i n g a l k a l i n e pH, h i g h S i grid Mg, and l o w A 1 activity. diagenesis.

H e demonstrated t h a t most data s u g g e s t e d neoformation r a t h e r t h a n

S o l i d state t r a n s f o r m a t i o n o f smectite to p a l y g o r s k i t e as

proposed by Weaver and Beck (1977) i s n o t f a v o r e d as a major mechanism.

4 S i n g e r proposed a n e s s e n t i a l l y d e t r i t a l o r i g i n f o r deep marine p a l y g o r s k i t e , w i t h some o f h y d r o t h e r m a l o r i g i n , and most d e p o s i t s b e i n g neoformed i n t h e perimarine environment. Weaver and Beck (1977) i n c l u d e a summary of p e r i m a r i n e e n v i r o n m e n t s i n t h e i r p a p e r on t h e G e o r q i a - F l o r i d a p a l y g o r s k i t e mines o f U.S.A.,

concluding

t h e y a r e dominant e n v i r o n m e n t s of n e o f o r m a t i o n . Lomova (1979) summarizes* some of t h e DSDP and o t h e r c o r i n g p r o j e c t s i n t h e oceans a s well as much data from t h e c o n t i n e n t s , and d i v i d e s d e p o s i t s i n t o the followinq types:

t e r r i g e n o u s c l a s t i c ' , chemogenic e v a p o r i t i c , p y r o c l a s t i c ,

v o l c a n i c h y d r o t h e r m a l , pedogenic,

h y d r o t h e r m a l v e i n s , and c o n t a c t metamorphic

o r a l t e r a t i o n zones around o r e b o d i e s .

This a u t h o r i n c l u d e s playa-lake

and

s h a l l o w l a c u s t r i n e t y p e s i n t h e p e d o g e n i c group, and f a v o u r s widespread neoformation i n o c e a n s from v o l c a n i c d e t r i t u s and h y d r o t h e r m a l a c t i v i t y .

An

a r i d e n v i r o n m e n t f o r c o n t i n e n t a l d e p o s i t s i n R u s s i a i s emphasized and m o s t of t h e major R u s s i a n d e p o s i t s a r e d i s c u s s e d i n some d e t a i l .

Lomova b e l i e v e s

p a l y g o r s k i t e s can form i n humid a r e a s , p r o v i d e d t h e r e i s an abundance of basic volcaniclastics

o v e r a l l t h e r e is a g r e a t e r emphasis on h y d r o t h e r m a l and

v o l c a n i c i n f l u e n c e i n g e n e s i s t h a n i s g i v e n most " w e s t e r n " l i t e r a t u r e . b r i e f r e v i e w by Gradusov ( 1 9 7 6 ) , however,

p l a c e s more emphasis on a d e t r i t a l

o r i g i n i n t h e o c e a n s , w i t h n e o f o r m a t i o n i n s o i l s and p e r i - m a r i n e C o u t u r e (1977,a,b)

The

environments.

s t u d i e d o c e a n i c d e p o s i t s , and s u g g e s t e d d i a q e n e s i s

from smectite and v o l c a n i c d e t r i t u s ,

though t h e e v i d e n c e f o r t h i s i s n o t

c o n v i n c i n g (Beck and Weaver, 1978).

Decarreau e t a l . ( 1 9 7 5 ) , on t h e o t h e r

hand, p r o v i d e some e v i d e n c e s u p p o r t i n g d i a g e n e s i s from degraded f e r r i f e r o u s b e i d e l l i t e i n r e s t r i c t e d m a r g i n a l marine c o n d i t i o n s .

A g r i c u l t u r a l i n v e s t i g a t i o n s have p r o v i d e d l a r g e numbers of c l a y a n a l y s e s , r e s u l t i n g i n t h e d i s c o v e r y of h i g h - p e r c e n t a g e s of p a l y g o r s k i t e s i n c a l c a r e o u s s o i l s and calcretes over a wide area ( F i g . 1 1.

Many of t h e s e c o n t a i n

p a l y g o r s k i t e as c u t a n i c f i l m s o f o r i e n t e d f i b r e s on s k e l e t o n g r a i n s or j o i n t ( p e d ) s u r f a c e s , i n d i c a t i n g n e o f o r m a t i o n i n t h e s o i l (Perelman, 1950, van den Heuvel,

1966, S i n g e r and N o r r i s h ,

1981, Hutton and Dixon,

1981).

1974,

Eswaran and B a r z a n j i , 1974, W a t t s ,

Many o t h e r s are s a i d to be i n h e r i t e d from

* c o m m e n t s b a s e d on p a r t i a l t r a n s l a t i o n f r o m R u s s i a n t e x t by W.V. P r e i s s , S o u t h A u s t r a l i a n D e p a r t m e n t of M i n e s a n d E n e r g y .

5

PALYGORSKITES 0 m.y. LATE PLIOCENE

- HOLOCENE

Fig. 1 . L a t e P l i o c e n e - Holocene p a l y g o r s k i t e s e p i o l i t e o c c u r r e n c e s . Dots a r e g e n e r a l i z e d DSDP and o c e a n i c o c c u r r e n c e s , d i a g o n a l s h a d i n g i s c o n t i n e n t a l d a t a . P r e f i x D i n d i c a t e s s o i l or c a l c r e t e . Cross-hatched a r e a s a r e s o i l s superposed on sedimentary b a s i n s w i t h p a l y g o r s k i t e . See Appendix 11.3 f o r r e f e r e n c e s . I s r a e l i occurrences are D3, D24, D25, D30, D31, Lebanon D13A. u n d e r l y i n g material, or added by a e o l i a n t r a n s p o r t , though t h i s i s l i k e l y to have been overemphasized i n e a r l y s t u d i e s through l a c k o f knowledge of t h e submicroscopic d i s t r i b u t i o n w i t h i n the s o i l f a b r i c .

The d e r i v e d s o i l s a t

l e a s t demonstrate p a l y g o r s k i t e s are s t a b l e i n t h e s e environments, though a few show evidence of p r e s e n t day d e g r a d a t i o n (e.g.

Nahon and R u e l l a n , 1975, Bigham

e t al., 1980). The v a l u e o f the l a t e Neogene p a l y g o r s k i t e o c c u r r e n c e s i n t h e p r e s e n t s t u d y is to i d e n t i f y t h e climatic zone i n which p a l y g o r s k i t e s are p r e s e r v e d , and demonstrate t h a t many such o c c u r r e n c e s were neoformed w i t h i n c e r t a i n latitudinal l i m i t s .

They also show t h a t t h e s e s o i l s are a major s o u r c e o f

f i b r o u s c l a y m i n e r a l s f o r t h e oceans, through e r o s i o n .

The plots show t h a t

a l l of t h e s o i l s l i e w i t h i n t h e p r e s e n t day d r y Mediterranean to a r i d climatic

belts.

A non-random

d i s t r i b u t i o n of o r i g i n a l c l a y sample p o i n t s can be

reasonably assumed, as r o u t i n e c l a y a n a l y s e s o f s o i l s are undertaken by most c o u n t r i e s , e x c e p t perhaps i n some c e n t r a l A f r i c a n n a t i o n s , South and C e n t r a l America and s o u t h e a s t A s i a .

Frozen ground a t l a t i t u d e s h i g h e r t h a n 80° would

also be a f a c t o r p r e v e n t i n g sampling.

Many of t h e s o i l s and c a l c r e t e s c o n t a i n i n g p a l y g o r s k i t e s are p r o b a b l y quite old. Australia,

1981) i n

The calcretes of t h e Murray B a s i n ( H u t t o n and Dixon,

f o r example are most l i k e l y s e v e r a l hundred thousand y e a r s o l d

(Cook e t a l . ,

1976, and u n p u b l i s h e d work o f t h e a u t h o r ) .

Thus, a l t h o u g h many

of these s o i l s are now a t the E a r t h ' s s u r f a c e and even used i n a g r i c u l t u r e , t h e y are l i k e l y t o be relic, and may n o t have formed under t h e c l i m a t i c c o n d i t i o n s of t h e p r e s e n t .

Calcrete d e p o s i t s were p r o b a b l y common i n t h e more

a n c i e n t p a s t ; Watts ( 1 9 7 6 ) h a s d e m o n s t r a t e d t h e p r e s e n c e of p a l y g o r s k i t e i n T r i a s s i c calcretes.

Pre-Neogene

c a l c r e t e and s o i l o c c u r r e n c e s have n o t o f t e n

been r e c o r d e d , p r o b a b l y because o f t h e s m a l l volume o f s u c h materials p r e s e r v e d i n t h e s e d i m e n t a r y r e c o r d compared w i t h s e d i m e n t s , and also b e c a u s e

of t h e l a c k of c l a y m i n e r a l s t u d i e s on s u c h materials and d i f f i c u l t y i n r e c o g n i t i o n of a n c i e n t s o i l s .

Only r e c e n t l y h a s i t been r e a l i z e d t h a t t h e y

can be a major p a l y g o r s k i t e - f o r m i n g environment. Large amounts of p a l y g o r s k i t e s are p r e s e n t i n P l i o - P l e i s t o c e n e

sediments

around t h e A t l a n t i c Ocean i n t h e same l a t i t u d e s as t h e s o i l s and p l a y a s .

In

t h e n o r t h e r n I n d i a n o c e a n , Goldberg and G r i f f i n (1970, p. 532), from comprehensive c o r i n g of bottom s e d i m e n t s , s u g g e s t e d p a l y g o r s k i t e w a s a n a e o l i a n i n p u t from N.

I f t h i s e v i d e n c e is coupled

Africa and S o u t h Arabia.

w i t h t h a t o f windblown d u s t , t o t h e p r e s e n c e o f i n t e r c a l a t e d r e d d e s e r t s a n d s and p a l y g o r s k i t e c l a y i n t h e A t l a n t i c a d j a c e n t t o n o r t h e r n A f r i c a (Chamley e t al.,

1 9 7 7 ) , and t o e v i d e n c e from t h e N.

P a c i f i c Ocean ( L e i n e n and Heath,

19811, it i s c l e a r t h a t many of t h e l a t e Neogene o c e a n i c d e p o s i t s are c l o s e l y

related t o l a t i t u d e s i n which d r y windy c o n d i t i o n s and p a l y g o r s k i t e - b e a r i n g soils prevail. I t i s known from d u s t a n a l y s e s t h a t p a l y g o r s k i t e s c a n be c a r r i e d i n s i g n i f i c a n t q u a n t i t i e s over long d i s t a n c e s (e.g.

Bain and T a i t ,

19771, hence

t h e e r o s i o n of p a l y g o r s k i t i c soils i n t h e a r i d zones and r e d e p o s i t i o n i n t h e o c e a n s i s a phenomenum of p r e s e n t - d a y Soil-derived

environments.

d e p o s i t s , whether from windblown d u s t o r stream erosion, a r e

t r a n s p o r t e d i n t o d e e p e r waters by t u r b i d i t y c u r r e n t s and slumps (Chamley, 1979, Melieres, 1978, Chamley e t a l . ,

1979).

The d i s t r i b u t i o n of

p a l y g o r s k i t e s w i t h age s h o u l d t h e r e f o r e give s o m e i n d i c a t i o n o f t h e d r i e r

climatic r e g i o n s i n t h e g e o l o g i c a l r e c o r d , f o r b o t h non-marine environments.

and marine

I n marine c o n d i t i o n s a much more c r u d e d i s t r i b u t i o n would be

e x p e c t e d b e c a u s e o f the e f f e c t s of ocean c u r r e n t s . A number o f p l a y a d e p o s i t s

s t i l l forming (McLean e t a l . ,

are of c o m p a r a t i v e l y r e c e n t o r i g i n , or are

1972, S t o e s s e l and Hay, 1978, Kautz and P o r a d a ,

1 9 7 6 ) , and t h e s e a l s o f a l l w i t h i n t h e same l a t i t u d i n a l b e l t .

Occurrences

neoformed i n l a k e s and p l a y a s are much commoner i n many C a i n o z o i c and o l d e r s e d i m e n t s ( C a l l e n , 1977, V e r z e l i n e t a l . ,

1973).

7

L ~ ~ h o f a c ~ e . - o f _ o l d e g_oEkit-es r~~Y Land - b a s e d d e p o s i t s The l i t h o f a c i e s a s s o c i a t e s of past p a l y g o r s k i t e s s h o u l d r e v e a l whether c o n d i t i o n s o u t l i n e d above a p p l y t h r o u g h o u t t h e g e o l o g i c r e c o r d .

There i s one

o b v i o u s d i f f e r e n c e which i s i m m e d i a t e l y d i s c e r n e d ; t h e p e r i - m a r i n e environment has been an i m p o r t a n t environment o f g e n e s i s i n t h e p a s t (Appendix 1 . 4 ) , b u t

i s p o o r l y r e p r e s e n t e d i n modern t i m e s .

The s t u d y of Weaver and Beck ( 1 9 7 7 ) o f

i s t h e b e s t known

m a r g i n a l marine f a c i e s i n F l o r i d a and G e o r g i a , U . S . A . example a n d : i n c l u d e s a world-wide

summary of p e r i - m a r i n e

deposits.

Readers

a r e r e f e r r e d t o t h e i r report f o r f u r t h e r d e t a i l s . A l l t h e d e p o s i t s ( m a r i n e and nonmarine) on p r e s e n t landmasses a r e

dominated by d o l o m i t e s ,

limestones,

f i n e o r sometimes coarse c l a s t i c s , and are

o f t e n a s s o c i a t e d w i t h e v a p o r i t e s , or p h o s p h a t e s ,

and c h e r t .

Palygorskites

a p p a r e n t l y p r e c i p i t a t e o r form w i t h i n t h e s e d i m e n t i n c o n d i t i o n s less s a l i n e t h a n t h o s e conducive to gypsum p r e c i p i t a t i o n .

The magnesium- c l a y s are o f t e n

found p e r i p h e r a l to e v a p o r i t e d e p o s i t s , o r above o r below such d e p o s i t s (Chamley e t a l . , Gradusov,

1976).

1978, HSU e t a l . ,

1973, C i t a , 1979, V e r z e l i n e t al.,

1973,

Other d e p o s i t s a r e a s s o c i a t e d w i t h p h o s p h a t e s , p a r t i c u l a r l y

i n A f r i c a n e p e i r i c seas of L a t e C r e t a c e o u s t o Eocene a g e , and i n t h e Gulf of Mexico r e g i o n ( M i l l o t , 1964, I s p h o r d i n g ,

1972, Weaver and Beck, 1 9 7 7 ) .

These

p h o s p h a t e s are of t h e s h a l l o w w a r m s h e l f t y p e , where n u t r i e n t s f o r t h e p h o s p h a t i c o r g a n i s m s are r e p l e n i s h e d by wind-induced

u p w e l l i n g s n e a r t h e edge

of t h e c o n t i n e n t a l s h e l f ( B i r c h , 1980. Giresse, 1980, Boujo e t a l . , The m a j o r i t y of non-marine d o l o m i t e (e.g.

1980).

p a l y g o r s k i t e s are i n t i m a t e l y r e l a t e d to

S i t t l e r , 1964, Suguio, 1975, C a l l e n , 1 9 7 7 ) . and are o f t e n

a s s o c i a t e d w i t h anomalous barium and s t r o n t i u m values.

. These d o l o m i t e s are

f r e q u e n t l y of t h e t y p e formed i n t h e zone of mixing between Mg-charged w a t e r s and s a l i n e l a k e s

CI

p l a y a s (Muir e t al.,

i n a Coorong-type environment.

1980, C a l l e n ,

fresh

19771, p e r h a p s

R e c e n t l y Turchenek and Oades ( t h i s volume) and

Hutton and Dixon ( 1 9 8 1 ) have shown p a l y g o r s k i t e forms up t o 75% of t h e f i n e f r a c t i o n ( o f t e n n e a r 1 0 0 % ) of s o i l samples and calcretes i n the palaeo-Coorong s e t t i n g of t h e s o u t h e a s t d i s t r i c t of S o u t h A u s t r a l i a . Turchenek and Oades are, however, o l d P l e i s t o c e n e beach r i d g e s .

l a t e Holocene.

The s o i l s d e s c r i b e d by

They are l o c a t e d between t h e

Thus t h e s u g g e s t i o n of W i e r s m a (1970) t h a t t h i s

is a p a l y g o r s k i t e - b e a r i n g environment i s correct.

However, it was found that

i n t h e Coorong, p a l y g o r s k i t e s do n o t occur where carbonates are p r e s e n t l y being p r e c i p i a t e d communication).

( C a l l e n , u n p u b l i s h e d a n a l y s e s , von d e r Borch, personal P a l y g o r s k i t e i s a l s o found i n v a l l e y s between t h e b e a c h

r i d g e s of t h e M e d i t e r r a n e a n coast of Egypt, which r e s e m b l e s t h e s i t u a t i o n i n s o u t h e a s t e r n S o u t h A u s t r a l i a (Hassouba and Shaw, 1 9 8 0 ) .

8

Few s t u d i e s of modern sabkha e n v i r o n m e n t s have l o c a t e d p a l y g o r s k i t e s , and i n t h e s e t h e c l a y s are b e l i e v e d to have been t r a n s p o r t e d from e l s e w h e r e (Seibold e t al.,

1973).

Oceanic d e p o s i t s I n the p r e s e n t open marine s i t u a t i o n p a l y g o r s k i t e s a r e found i n t h r e e t y p i c a l s e d i m e n t a r y a s s o c i a t i o n s i n waters of v a r y i n g d e p t h :

(il

With d i s t u r b e d s e d i m e n t s or t u r b i d i t e s .

(ii)

P e r i m a r i n e f a c i e s which have s,ubsided i n t o d e e p w a t e r (Enos and

(iii

With c h a l k o r t h e " c a l c a r e o u s ooze" f a c i e s o f Kidd and Davies

Freeman, 1 9 7 9 ) , or formed i n t h e e a r l y s t a g e s of opening of o c e a n s .

(1978).

The f i r s t a s s o c i a t i o n i s t y p i c a l of A t l a n t i c Ocean p a l y g o r s k i t e s .

There

is no d o u b t t h a t slumps and t u r b i d i t e s p l a y a major r o l e i n r e d i s t r i b u t i n g s h a l l o w c o n t i n e n t a l s h e l f material i n t o d e e p e r waters.

P a l y g o r s k i t e s i n such

d e p o s i t s are d i s c u s s e d i n t h e r e f e r e n c e s g i v e n e a r l i e r . The second a s s o c i a t i o n needs no f u r t h e r comment e x c e p t to .suggest t h a t c o n d i t i o n s i n t h e e a r l y o c e a n s would p r o b a b l y have been similar to t h e M e d i t e r r a n e a n Sea d u r i n g and j u s t a f t e r t h e M e s s i n i a n s a l i n i t y e v e n t (Chamley

e t al.,

1978, HSU e t a l . ,

1973, Rouchy, 1 9 8 0 ) .

The t h i r d a s s o c i a t i o n i s c l e a r l y shown by an example from the I n d i a n P l o t t i n g p a l y g o r s k i t e z o n e s ( F i g . 2 ) on t h e f a c i e s - t i m e - d e p t h

Ocean.

curves

of Kidd and D a v i e s (1978) d e m o n s t r a t e s the i n t e r v a l s o f p a l y g o r s k i t e s e d i m e n t a t i o n c o i n c i d e w i t h calcareous ooze (or sometimes " o t h e r c l a y s " o f Kidd and D a v i e s , 1 9 7 8 ) , d e p o s i t e d i n water of v a r i a b l e d e p t h , i n c l u d i n g v e r y d e e p waters.

Thus, as f o r l a n d d e p o s i t s ,

the carbonate facies.

ther e i s a general associ at i on with

A s i m i l a r a s s o c i a t i o n i s r e p o r t e d f o r the S h a t s k y rise

o f t h e n o r t h w e s t e r n P a c i f i c Ocean ( Z e m m e l s , 1976, Matti e t a l . ,

1973, Gorbunova, 1 9 7 2 ) .

1973, Z e m m e l s and Cook, 1973, W e s h a l l see l a t e r when

c o n s i d e r i n g t h e i r o r i g i n , t h a t t h e s e d e p o s i t s f r e q u e n t l y overlie e x t e n s i v e b a s a l t i c f l o w s of s i m i l a r age (Despraires, 1 9 8 2 ) .

-----SUlnUG3I-y The Plio-Holocene

d e p o s i t s d e m o n s t r a b l y formed i n a l k a l i n e - b r a c k i s h

waters i n a M e d i t e r r a n e a n / a r i d climate, and i n s o i l s and c a l c r e t e s , h e n c e o l d e r d e p o s i t s may have also formed under s i m i l a r c i r c u m s t a n c e s .

The a r i d

climatic a s s o c i a t i o n i s confirmed from t h e l i t h o f a c i e s o f o l d e r p a l y g o r s k i t e s , hence p a l a e o l a t i t u d i n a l p l o t s might be e x p e c t e d to reveal past d i s t r i b u t i o n of 'arid'

climatic b e l t s .

The g r e a t e r e x t e n t of p e r i m a r i n e d e p o s i t s p r i o r t o t h e

Neogene i n d i c a t e s that p a l a e o c o n t i n e n t a l p l o t s of r e s u l t s from the Deep Sea D r i l l i n g P r o j e c t would assist i n d e f i n i n g l a t i t u d i n a l d i s t r i b u t i o n s .

9

TIME (m.v.)

12561

PALYGORSKITES EASTERN INDIAN

1212)

WESTERN INDIAN

1214

z ~ o

GAPS REPRESENT HIATUSES

Drn 1 t

Fig. 2. P a l y g o r s k i t e s i n the I n d i a n O c e a n - p a l a e o d e p t h c u r v e s , a d a p t e d from f i g . 5 o f Kidd & D a v i e s , 1978. N o t e l a c k of r e l a t i o n s h i p between p a l y g o r s k i t e and depth. P a l y g o r s k i t e s are a s s o c i a t e d w i t h " c a l c a r e o u s ooze" f a c i e s , e x c e p t i n 250, 252 ( " o t h e r t y p e s " - Cretaceous d e e p sea c l a y ) , 223 (Neoqene " t e r r e g i n o u s s e d i m e n t s " ) , and 213, 215, 220, 221, 256 (small amounts i n Neogene " o t h e r t y p e s " o f c l a y , " t e r r e g i n o u s s e d i m e n t s " and " s i l i c e o u s ooze" 1. Windblown d u s t is e s s e n t i a l l y d e r i v e d from a r i d a r e a s , and many deep ocean d e p o s i t s come from slumping of p e r i m a r i n e o c c u r r e n c e s ( i n c l u d i n g d u s t d e p o s i t s ) hence even t h e d e e p ocean p l o t s might show a l a t i t u d i n a l distribution related to ' a r i d i t y ' ,

p r o v i d M t h e r e are no problems w i t h sample

distribution.

LATITUDINAL DISTRIBUTICN Sampling Bias --_ --- -____ The s i g n i f i c a n c e of t h e d i s t r i b u t i o n s can o n l y be a s s e s s e d a f t e r d e t e r m i n i n g whether t h e o r i g i n a l samples w e r e randomly d i s t r i b u t e d or not. Both l a n d and DSDP o c c u r r e n c e s are a f f e c t e d by d i f f i c u l t y of access i n t h e

polar r e g i o n s due to ice, hence t h e s e zones are n o t c o n s i d e r e d i n t h e s t u d y . A second factor is i n t r o d u c e d by t h e change i n area of e a c h l a t i t u d i n a l slice,

which d e c r e a s e s by a b o u t 4x p r o c e e d i n g from e q u a t o r to p o l e .

Thus a s p e c i f i c

number of samples i n t h e h i g h e r l a t i t u d e s are of more s i g n i f i c a n c e w i t h respect to c o n c e n t r a t i o n t h a n t h e same number n e a r t h e e q u a t o r .

10

Deposits on land must be a s s e s s e d s e p a r a t e l y from DSDP r e s u l t s f o r t h e

following reasons: D e p o s i t s on p r e s e n t landmasses are p l o t t e d i n terms of b a s i n s ,

to

a v o i d t h e b i a s t h a t would be caused by r e p e a t e d s t u d i e s of t h e same

s o r t i n one series of r e l a t e d beds.

Any area once s t u d i e d t e n d s t o

a t t r a c t f u r t h e r s t u d i e s and r e f i n e m e n t s .

DSDP h o l e s on t h e o t h e r

hand, are s i n g l e s p o t o c c u r r e n c e s . The o r i g i n a l sample d i s t r i b y t i o n i s known f o r DSDP h o l e s , whereas i t

i s n o t f o r land-based d e p o s i t s .

For

the l a t t e r , one must assume an

even coverage o f r o c k s o f a l l a g e s i n a l l c o u n t r i e s , o b v i o u s l y a r a t h e r i d e a l i s t i c assumption (see ( 3 ) ) . The d i s t r i b u t i o n of land d e p o s i t s 'depends on t h e i n d i v i d u a l e f f o r t s o f c e r t a i n groups, o f t e n working w i t h i n c e r t a i n t e r r i t o r i a l l i m i t s , and a l s o i n f l u e n c e d by a c c e s s i b i l i t y .

DSDP r e s u l t s are a n

i n t e r n a t i o n a l e f f o r t , w i t h c o m p a r a t i v e l y u n l i m i t e d access.

Accepting t h a t t h e two sets of d a t a must be c o n s i d e r e d s e p a r a t e l y , a n o t h e r problem arises. and t i m e .

The d i s t r i b u t i o n of l a n d and sea v a r i e s with l a t i t u d e

For example t h e r e i s much more l a n d i n t h e n o r t h e r n m i d - l a t i t u d e s ,

hence one would e x p e c t more r e s u l t s from t h i s area.

-

A few o c c u r r e n c e s i n a

b e l t w i t h l i t t l e l a n d are more s i g n i f i c a n t t h a n t h e same number i n a b e l t w i t h much l a n d , and c o n v e r s e l y f o r t h e oceans.

Then, phenomena such as t h e

northward d r i f t o f I n d i a and A u s t r a l i a s i g n i f i c a n t l y change t h e d i s t r i b u t i o n o f l a n d and sea w i t h t i m e . Taking l a n d d e p o s i t s f i r s t , a n estimate of t h e r e l a t i v e c o n c e n t r a t i o n per l a t i t u d e w a s made by d i v i d i n g t h e number o f o c c u r r e n c e s , i n t e r m s of b a s i n s , by t h e area of each 10'

l a t i t u d i n a l belt.

This was a d j u s t e d c r u d e l y f o r land

area by d i v i d i n g by t h e f r a c t i o n of l a n d i n each b e l t , e s t i m a t e d by eye from mercator p r o j e c t i o n s of each t i m e i n t e r v a l ( u s i n g t h e maps of Smith and Briden, 1 9 8 0 ) .

D i f f e r e n t f a c t o r s w e r e t h e r e b y d e r i v e d f o r Oo-30°

i n t h e n o r t h and s o u t h hemispheres.

and 30°-60'

A more a c c u r a t e r e s u l t could be o b t a i n e d

by t a k i n g 10' b e l t s and c a l c u l a t i n g by p l a n i m e n t r y , b u t t h i s i s h a r d l y j u s t i f i e d c o n s i d e r i n g the number of d a t a p o i n t s and the o t h e r u n c e r t a i n t i e s . A d i f f e r e n t and perhaps more r e l e v a n t approach could be made by i n c o r p o r a t i n g

d a t a on e p i c o n t i n e n t a l seas, which could change t h e f a c t o r s s i g n i f i c a n t l y , b u t t h i s h a s n o t been accomplished a t t h i s s t a g e . Adding t h e r e s u l t i n g f i g u r e s f o r each t i m e i n t e r v a l , and p l o t t i n g by l a t i t u d e , g i v e s Fig.

3A.

The r e s u l t i s o b v i o u s l y non random, d e m o n s t r a t i n g a

c o n c e n t r a t i o n i n l a t i t u d e s 1 0'-40°N, Pliocene-Holocene

e s p e c i a l l y 30'-40°N,

and 3Oo-4O0S.

The

r e s u l t s are n o t i n c l u d e d because o f t h e i m p o s s i b i l i t y o f

11

t

I

400

Lend deDosits 0

300 c

0 I

A

100

-L

I

$ u0

100

r 50

20 Lal

N

I

-TT-+ de

1 50

S

300

B

50 Latitude

N

60

S ~

-

8

Palygorskite in

DSDP holes

0 Lalntude

N Drn JPV

80

82-34

S

5 A Department of Mmes and Energy

Fig. 3. L a t i t u d i n a l d i s t r i b u t i o n of p a l y g o r s k i t e s i n terms of 1 O o i n t e r v a l s . A. C o n t i n e n t a l r e c o r d s i n terms of b a s i n s . C o n c e n t r a c t i o n f a c t o r approximately a d j u s t e d for l a t i t u d e and l a n d area. P l i o - P l e i s t o c e n e o c c u r r e n c e s n o t i n c l u d e d . See t e x t f o r method of e s t i m a t i o n . B. A l l DSDP h o l e s i n terms of 1 0 M a t i m e slices, t o t a l l e d . C. P a l y g o r s k i t e s r e c o r d e d on p r e s e n c e or absence b a s i s f o r each s i t e per 10 Ma t i m e slices. Shaded area r e p r e s e n t s sites shown as l a r g e d o t s on d r i f t maps (*: greatest c o n c e n t r a t i o n i n < 2 u f r a c t i o n ) .

r e c o r d i n g t h e e x t e n s i v e s o i l o c c u r r e n c e s as s i n g l e b a s i n s .

The s i g n i f i c a n c e

o f t h e s e younger d e p o s i t s h a s a l r e a d y been d i s c u s s e d . Taking t h e o c e a n i c o c c u r r e n c e s , 3B i s obtained.

on Fig.

e s s e n t i a l l y from DSDP r e s u l t s ,

the plot

The p a l y g o r s k i t e o c c u r r e n c e s have been r e c o r d e d

a g a i n s t l a t i t u d e on a h i s t o g r a m ( F i g . 3C), f o r DSDP h o l e s , by t o t a l l i n g a l l h o l e s c o n t a i n i n g p a l y g o r s k i t e s f o r e a c h 1 0 My t i m e s l i c e i n e a c h 10' l a t i t u d i n a l belt. hemisphere, However,

The d i s t r i b u t i o n i s s t r o n g l y skewed toward t h e n o r t h e r n

w i t h zones of most abundance between 1 0'-30°N

F i g . 38

and 30'-40°S.

d e m o n s t r a t e s t h a t t h e o r i g i n a l sample d i s t r i b u t i o n is b i a s e d

i n t h e same way towards c e r t a i n l a t i t u d e s , t h e s e b e i n g e s s e n t i a l l y t h e same o n e s as f ? r l a n d - d e p o s i t s

( F i g s 1 , 10-12) by c o i n c i d e n c e .

Thus t h e r e is no

proof t h a t o c e a n i c o c c u r r e n c e s are s i g n i f i c a n t l y c o n c e n t r a t e d i n c e r t a i n l a t i t u d e s , e x c e p t p o s s i b l y i n 20-30°N and 30-40's.

'Ancient' D e p o s i t s

This latter concentration

d e p o s i t s i n t h e s e same l a t i t u d e s .

may be t h e r e s u l t of e r o s i o n o f t h e ' l a n d ' ( F i g . 4).

The s c a r c i t y of r e s u l t s from pre-Mesozoic l a c k of o c e a n f l o o r of t h i s age.

t i m e s i s p a r t l y t h e r e s u l t of

I n a d d i t i o n , v e r y few d e e p ocean d e p o s i t s

have been r e c o g n i z e d i n p r e s e n t c o n t i n e n t a l areas, which i s s u r p r i s i n g c o n s i d e r i n g t h e g r e a t e x t e n t o f t h e p a l a e o - P a c i f i c Ocean.

Those d e e p s e a

s e d i m e n t s t h a t have been r e c o g n i z e d have no d e t a i l e d c l a y mineralogy.

Lack of

o l d e r d e p o s i t s i s a l s o caused by t h e loss of h y d r o x y l water above 40OoC and d i s s o l u t i o n of p a l y g o r s k i t e above 800°C

( K u l b i c k i , 1959.

Thus p r i m a r y

p a l y g o r s k i t e o r s e p i o l i t e would n o t s u r v i v e h i g h g r a d e metamorphism. A l l b u t one of t h e ' A n c i e n t '

occurrences

30° o f t h e e q u a t o r i n s h a l l o w land-locked

Russia.

(Fig. 4 ) a r e concentrated within

seas of c e n t r a l and w e s t e r n

The a p p a r e n t l y anomalous S i b e r i a n o c c u r r e n c e may be of marine

h y d r o t h e r m a l o r i q i n ( D i v i n a e t al.,

19781, p e r h a p s d e p o s i t e d i n a f o r - a r c

t r o u g h l i k e t h e p a l y g o r s k i t e of t h e Marianas t r e n c h ( D e s p r a i r e s , 19821, though t h e s e d i m e n t s d o n o t seem to f i t t h i s model.

The most e x t e n s i v e d e p o s i t s are

Devonian t o Permian i n a g e , a s s o c i a t e d w i t h p l a t f o r m d o l o m i t e s and o t h e r carbonates. I t i s l i k e l y t h a t o t h e r s u c h d e p o s i t s w i l l be d i s c o v e r e d , b e c a u s e t h e r e

are few a d e q u a t e s t u d i e s of t h e c l a y m i n e r a l o g y of s u c h s e q u e n c e s .

These

c o u l d r a d i c a l l y a l t e r t h e p a t t e r n of t h i s d i s t r i b u t i o n . Mesozoic and C a i n o z o i c D e p----osits ___________________-----P a l y g o r s k i t e s are widely,

though d i f f u s e l y s p r e a d t h r o u g h t h e a r i d

T r i a s s i c r o c k s o f n o r t h A f r i c a and Europe, ( F i g . 4, t o p l e f t ) , r e a c h i n g c o n c e n t r a t i o n s of 50% o r more i n t h e p h o s p h a t i c r o c k s of tbrocco (Krumm, 1969).

As f o r many of t h e C a r b o n i f e r o u s occurrences o f R u s s i a ,

they w e r e

r e s t r i c t e d t o a series of s h a l l o w l a n d l o c k e d seas and s a l i n e l a k e s , c l o s e t o t h e equator.

13

TRIASSIC 190 M a

//-\

PERMOCARBONIFEROUS 280 M a

N

DEVONIAN

Land---)rn

Marine Shelf

-

CAMBRIAN

B m 82-70 SADME

J.PV

Fig. 4. ‘Ancient’ and T r i a s s i c occurrences ( p l o t t e d on Eckert P r o j e c t i o n s simplified from Kanasewick, e t a l . (1978). There a r e few records from t h e J u r a s s i c t o Early Cretaceous ( F i g s 5 , 6 and

l o ) , though Early J u r a s s i c and Aptian-Albian

d e p o s i t s a r e prominent i n t h e

newly opened North A t l a n t i c Ocean northwest of Austral-Antartica, proto-Pacific

Ocean.

and i n t h e

Environments i n t h e A t l a n t i c Ocean probably resembled

those of the Triassic s e a s and t h e Late Miocene of t h e Mediterranean Sea (Hsu e t al.,

1973).

Chamley (1979) has given a d e t a i l e d h i s t o r y of t h e development

14 of t h e A t l a n t i c Ocean deposits through t o modern t i m e s ,

emphasizing t h e role

of t h e p e r i m a r i n e environment, and d e s c r i b i n g how t h i s r e t r e a t e d from t h e c e n t r a l ocean area as r i f t i n g developed.

I

PORTLANDIAN TO MIDDLE BERRIASIAN

MIDDLE OXFORDIAN TO KlMMERlDGlAN ,900 , ,150my

-.

42% P+S or isolated high % samples - - 2-10% P+S in beds of decimetricthickness - -A

)lo%

P+S in bedsof decimetric thickness--

DSDP drillhole number

r.e.

- - - - - ---

-0

-223

Fig. 5

81-493

SADME

F i g s 5-9. DSDP o c c u r r e n c e s p l o t t e d on p o l a r p r o j e c t i o n s of F i r s t b o o k e t a l . , (1979). See Fig. 5, f o r abundance key. S i t e numbers shown. Key t o r e f e r e n c e s appendix 1-1, 1-3 f o r % abundance i n t2 v f r a c t i o n . P o s i t i o n s approximate f o r 29; 10 Ma 87, 88, 139, t h e f o l l o w i n g : 40 Ma - 138, 171, 288, 460,459; 5 Ma 171,, 323, 333. S i t e 462 n o t p l o t t e d ( M a r s h a l l I s l a n d s - Nauru B a s i n ) .

-

-

Neoformation l a t e r became c o n c e n t r a t e d i n s h a l l o w seas l i k e t h e Gulf of Mexico and S t r a i t s of G i b r a l t a r ( F i g s 7, 8, lo), from which t r a n s p o r t i n t o t h e deep oceans w a s e f f e c t e d by t u r b i d i t y c u r r e n t s .

Such t r a n s p o r t methods

prevented s e v e r e breakage of t h e long p a l y g o r s k i t e and s e p i o l i t e f i b r e s . P r e v i o u s l y t h e p r e s e n c e of such f i b r e s had been a c c e p t e d a s evidence of "IN SITW'genesis (e.g.

Gorbunova, 1973).

Large amounts o f p a l y g o r s k i t e d u s t w e r e

probably a l s o f i n d i n g t h e i r way i n t o t h e seas a t t h i s t i m e (though t h e s e would be expected t o have much s h o r t e r f i b r e s , a f a c t o r which can be t e s t e d ) .

In

t h e s o u t h e r n I n d i a n ocean, t h e d i s t r i b u t i o n s ( F i g s 6-9, 10-12) s u g g e s t wind t r a n s p o r t from A f r i c a , and t h e r e are some d e p o s i t s i n t h e a d j a c e n t east A f r i c a n landmass which c o u l d have provided t h i s material.

15

900

LATE CENOMANIAN TO TURONIAN

LATE ALBIAN TO EARLY CENOMANIAN

goo

16

90'

PALEOCENE

90'

900

CAMPANIAN TO MAASTRICHTIAN

900

goo

rn T E

SANTONIAN TO CONlAClAN

Fig. 7

900

81-491

SADME

17

LATE EOCENE TO EARLY OLIGOCENE

my

90"

Drn TE

EARLY TO MIDDLE EOCENE

Fig. 8

90'

81-490

SADMI

18

I

LATE MIDDLE MIOCENE

SO"

Dm TE.

EARLY MIOCENE TO EARLY MIDDLE MIOCENE

Fig. 9

900

81-489

SADW

19 I n the c e n t r a l S o u t h A t l a n t i c , a b e l t of h i g h l y c o n c e n t r a t e d p a l y g o r s k i t e s may be r e l a t e d to s e d i m e n t s o f similar a g e on t h e a d j a c e n t c o n t i n e n t s ( F i g s 7-8, and t h e P o i n t - N o i r e Cretaceous

, India

10-111,

b e i n g the Bauru Basin ( S u g u i o , 1975) o f B r a z i l ,

Basin (Giresse, 1980) o f t h e Congo.

I n the Late

had d r i f t e d i n t o t h i s same l a t i t u d i n a l b e l t ( F i g . 1 0 ) and

p a l y g o r s k i t e s w e r e d e p o s i t e d i n a l k a l i n e l a k e s i n d e p r e s s i o n s i n t h e Deccan t r a p s (Aneesuddin, 1971 )

.

The Campanian was one of the main p e r i o d s of p a l y g o r s k i t e d e p o s i t i o n i n t h e o c e a n s , r g a c h i n g up t o 80% or more of t h e c l a y f r a c t i o n (Appendix 1 . 2 ; Fig.

1 3 ) i n e x t e n s i v e t h i c k c l a y - r i c h beds ( F i g s 7 , 1 0 ) .

T h i s w a s t h e t i m e of

major d e p o s i t i o n , e s p e c i a l l y i n t h e r e g i o n e q u i v a l e n t to t h e S h a t s k y R i s e i n t h e proto-Pacific Ocean.

A t t h e same t i m e ,

major nonmarine and m a r g i n a l

marine d e p o s i t s w e r e forming i n t h e Fergana t r o u g h of K h u r g i z s t a n , a r e g i o n which h a s a l o n g h i s t o r y o f p a l y g o r s k i t e d e p o s i t i o n from L a t e J u r a s s i c t o Pliocene.

N o r t h e r n hemisphere o c c u r r e n c e s o f t h e s e t i m e s e x t e n d t o 4OoN o f

t h e e q u a t o r , and are d i s t r i b u t e d m a i n l y beween 25'

and 40°.

T h i s w a s also t h e

b e g i n n i n g of e x t e n s i v e s h a l l o w marine e p i c o n t i n e n t a l sea d e p o s i t i o n i n North A f r i c a , where p h o s p h a t e s were p r o m i n e n t s e d i m e n t a r y a s s o c i a t e s of p a l y g o r s k i t e and s e p i o l i t e .

These e p i c o n t i n e n t a l seas w e r e comparable to t h o s e o f

A u s t r a l i a i n t h e L a t e J u r a s s i c to E a r l y C r e t a c e o u s , and y e t A u s t r a l i a h a s no

Mesozoic p a l y g o r s k i t e s .

T h i s is a t t r i b u t e d t o i t s h i g h - l a t i t u d e p o s i t i o n a t

this time. I n t h e M a a s t r i c h t i a n t o E a r l y EOcene ( F i g s 7-8,

10 t o p ) , zonal

d i s t r i b u t i o n i s n o t as clear, and o c c u r r e n c e s s p r e a d f u r t h e r n o r t h and s o u t h

t o l a t i t u d e s 45ON and 55's.

The l a c u s t r i n e d e p o s i t s of B r a z i l and s o u t h e r n

France w e r e p r o m i n e n t , as w e r e t h e I n d i a n Ocean and n o r t h w e s t A u s t r a l o -

Antarctica d e p o s i t s . The Middle Eocene t o E a r l y O l i g o c e n e map ( F i g . latitudinal distribution.

11, t o p ) shows a n a p p a r e n t

Non marine l a c u s t r i n e d e p o s i t s became more

a b u n d a n t , i n s i m i l a r l a t i t u d i n a l belts.

The main sites of d e p o s i t i o n were

around t h e Tethyan margin and i n t h e Gulf o f Mexico area. During the Middle Miocene, t h e l a t i t u d i n a l d i s t r i b u t i o n resembled t h a t of t h e L a t e P l i o c e n e to p r e s e n t day.

There w e r e e x t e n s i v e l a c u s t r i n e beds i n

A u s t r a l i a , Europe and A s i a ( F i g s . 11 top, and 1 2 ) . The i n t e r p l a y between marine and non-marine

environments is w e l l

d i s p l a y e d by t h e d e p o s i t s of the M e d i t e r r a n e a n Sea.

Here, p a l y g o r s k i t e c l a y s

are i n t e r b e d d e d w i t h some of t h e M e s s i n i a n e v a p o r i t e - d o l o m i t e (Chamley e t al.,

1978).

sequences

These were l a i d down i n b r a c k i s h l a k e waters of the

d r y o c e a n i c d e p r e s s i o n , which c o n t a i n e d a v a r i e t y of s h a l l o w s a l i n e e n v i r o n m e n t s a t t h i s t i m e (Rouchy, 1 9 8 0 ) .

After c o n n e c t i o n w i t h the A t l a n t i c

20

PALYGORSKITES 60 m.y. MAASTRICHTSAN - EARLY EOCENE

PALYGORSKITES 80 m.y. CONlAClAN

Fig. 10

- CAMPANIAN

21

PALYGORSKITES 20 m.y. LATE OLIGOCENE

- MIDDLE MIOCENE

PALYGORSKITES 40 m.y. MIDDLE EOCENE - EARLY OLIGOCENE

Fig. 11

22

PALYGORSKITES 10 m.y. MIDDLE MIOCENE - EARLY PLIOCENE

Fig. 12 F i g s 10-12. General d i s t r i b u t i o n , p l o t t e d as b a s i n s on Mercator p r o j e c t i o n s m o d i f i e d from Smith E B r i d e n , 1977. See a p p e n d i x 1 1 . 2 and 1.4 f o r d e t a i l s . D o t s are g e n e r a l i z e d DSDP and'oceanic'occurrences, d i a g o n a l s h a d i n g is c o n t i n e n t a l d a t a ( M : p a r t l y m a r i n e ) . Some'oceanic'occurrences p a r t l y nonsee t e x t ) . marine (e.9. M e d i t e r r a n e a n Sea Some d a t a from t h e c o n t i n e n t s a p p e a r on more t h a n one map by r e a s o n of l a c k o f a g e d e f i n i t i o n r a t h e r t h a n d e p o s i t i o n o v e r a l o n g t i m e span.

-

Ocean w a s r e - e s t a b l i s h e d

in t h e P l i o c e n e , t h e r e w a s a sudden i n c r e a s e i n

p a l y g o r s k i t e i n p e l a g i c oozes and t u r b i d i t e s of t h e c e n t r a l b a s i n s .

These

younger c l a y s are p r o b a b l y d e t r i t a l (Chamley e t a l , m 1978). d e r i v e d e i t h e r from eroded M e s s i n i a n

and p o s s i b l y o l d e r d e p o s i t s of t h e a d j a c e n t landmasses,

o r neoformed n e a r s h o r e and carried i n t o d e e p w a t e r d u r i n g t h e P l i o c e n e .

The

former is most l i k e l y as m a r g i n a l M e d i t e r r a n e a n s e d i m e n t a t i o n d i d n o t i n c l u d e s u i t a b l e environments f o r neoformation i n Late P l i o c e n e e x c e p t i n s o i l s a l o n g the A f r i c a n and I s r a e l i

-

-

Pleistocene t i m e s ,

Lebanon Coasts.

-__-__ SUmmaLy A l a t i t u d i n a l d i s t r i b u t i o n is recognizeable

p r o j e c t i o n p l o t s ( F i g s 1 , 10-12).

i n n e a r l y a l l t h e Mercator

The L a t e P l i o c e n e to p r e s e n t d a y

l a t i t u d i n a l p a t t e r n persists back i n t i m e a t l e a s t t o t h e L a t e O l i g o c e n e , and

i s also v i s i b l e i n t h e L a t e C r e t a c e o u s .

A l s o , p r i o r to t h e L a t e O l i g o c e n e ,

t h e r e is a t e n d e n c y f o r a g r e a t e r s p r e a d towards t h e e q u a t o r i n the d e p o s i t s

23 on p r e s e n t day landmasses.

C o n f i r m a t i o n of t h e s o u t h e r n hemisphere

l a t i t u d i n a l b e l t i s o b s c u r e d by l a c k of r e c o r d s from S o u t h A m e r i c a and South Africa. There a p p e a r s t o be a r e a l c o n c e n t r a t i o n of p a l y g o r s k i t e s on ' l a n d ' , between 30-40°

i n b o t h hemispheres.

The f a c t t h a t many of t h e s e are a c t u a l l y

p e r i m a r i n e o c c u r r e n c e s s u g g e s t s a s i m i l a r d i s t r i b u t i o n o u g h t t o be v i s i b l e i n the oceans.

T h i s i s d i f f i c u l t t o d e t e r m i n e b e c a u s e m o s t DSDP d r i l l i n g was

done, c o i n c i d e n t a l l y , i n t h e s e same l a t i t u d e s , c r e a t i n g a n i n i t i a l b i a s i n t h e sample p a t t e r n .

The o c e a n i c DSDP d i s t r i b u t i o n t h e r e f o r e S u g g e s t s a n even

s c a t t e r i n most l a t i t u d e s , g i v i n g no f i r m s u p p o r t from t h i s s t a t i s t i c a l basis t o t h e h y p o t h e s i s t h a t many o c e a n i c d e p o s i t s w e r e d e r i v e d by e r o s i o n from However, g e o l o g i c a l c r i t e r i a may s u g g e s t o t h e r w i s e , as

'land' deposits.

d i s c u s s e d , f o r example, i n t h e A t l a n t i c Ocean. Non-marine d e p o s i t s are most e v i d e n t from t h e Eocene t o P l i o c e n e .

T I K S OF PALYGORSKITE ABUNDANCE The age d i s t r i b u t i o n of p a l y g o r s k i t e - s e p i o l i t e abundance i n t h e o c e a n s is d e m o n s t r a t e d by F i g .

13, a h i s t o g r a m of t o t a l and a v e r a g e p e r c e n t a g e of Table 1 summarizes t h e times of greatest

p a l y g o r s k i t e s and s e p i o l i t e .

abundance of d e p o s i t s on t h e c o n t i n e n t s and o c e a n s a s d e t e r m i n e d from F i g . 1 3 and Appendix 1.4.

The DSDP r e s u l t s show t h a t t h e p e a k s of s i m p l e a g g r e g a t e

percentage f o r a l l t h e h o l e s f o r each t i m e - s t r a t i g r a p h i c w i t h t h e a v e r a g e p e r c e n t a g e peaks.

Age u n i t c o i n c i d e s

~ are used, and Only o r i e n t e d < 2 samples

some d a t a w e r e n o t i n c l u d e d (see Methods s e c t i o n ) . from many a n a l y s e s i n one or two h o l e s ;

Some d a t a d e r i v e l a r g e l y

t h e c a p t i o n t o t h e g r a p h shows which

peaks come i n t o t h i s c a t e g o r y . I n t h e L a t e Miocene-Holocene,

t o t a l abundance i s h i g h , b u t a v e r a g e

p e r c e n t a g e l o w , and p e r u s a l o f t h e o r i g i n a l d a t a c o n f i r m s a l a r g e number of samples of l o w p e r c e n t a g e .

This i s t h e r e s u l t of t h e l a r g e number of bores,

t h e Q u a t e r n a r y sediments being t h e m o s t widespread,

t o g e t h e r with the l a r g e

number of c l o s e l y spaced samples from t h e s e b o r e i n t e r s e c t i o n s . s u i t a b l e l a t e Neogene p e r i - m a r i n e

e n v i r o n m e n t s may b e t h e r e a s o n f o r t h e low

a v e r a g e p e r c e n t a g e of p a l y g o r s k i t e s i n t h e s e o c c u r r e n c e s . have fewer p a l y g o r s k i t e - s e p i o l i t e

The l a c k of

The o l d e r s e d i m e n t s

b e a r i n g i n t e r v a l s b e c a u s e t h e amount of

ocean f l o o r d i m i n i s h e s t o z e r o i n t h e T r i a s s i c . Examination o f t h e d a t a of R o b e r t ( 1 9 8 1 ) and Chamley and R o b e r t ( 1 9 7 9 ) f o r t h e S o u t h A t l a n t i c , which is n o t i n c l u d e d i n t h e c a l c u l a t i o n s , coupled w i t h d a t a from h o l e s w i t h b u l k a n a l y s e s or n o n - o r i e n t a t e d (Appendix 1.31,

< 2 p samples

shows t h e same d i s t r i b u t i o n a s t h e h i s t o g r a m .

c o n f i r m s t h e e x i s t e n c e of t h e A l b i a n peak.

It a l s o

24

TOTAL %

""""4

5200 PLI LK

4800

TOTAL % PALYGORSKITE A N 0 SEPlOLlTE

_______

TOTAL % PALYGORSKITE A N 0 SEPlOLlTE AGGREGATED FOR EPOCHS

4400

________

4000

I

r P--

3600

I

AVERAGE % PALYGORSKITE AND SEPlOLlTE

________

3200

I

I

2800 P

AVE %

9

2400

50;

2000

40;

1600

n 0

1200

30: I

20j

800

I

400

10: I

0:

0

0

10

20 30 40 50

so

m TE

Fig. 1 3 . Age Ages, Epochs estimation. from 1 h o l e ,

70 80 90 100 110 t i 0 130 140 150 160 AGE 1m.y.) 82-26

SADME

d i s t r i b u t i o n of p a l y g o r s k i t e s : t o t a l and average % p l o t t e d by and P e r i o d s , f o r DSDP d r i l l i n g . See t e x t f o r method o f 10: Mainly from two h o l e s , 1E: m o s t l y 1 h o l e , Camp.: 50% d a t a Albian: dashed peak = d a t a from 1 h o l e . Data from appendix 1.3.

Some of t h e marine d e p o s i t s , such as t h o s e of t h e Mediterranean L a t e Miocene, and e a r l y oceans, are b e s t r e g a r d e d as l a c u s t r i n e whereas many of t h e d e p o s i t s on p r e s e n t landmasses are m a r g i n a l marine o r s h e l f environments.

The

r e s u l t s show t h a t from t h e L a t e C r e t a c e o u s onwards t h e main i n t e r v a l s o f d e p o s i t i o n c o i n c i d e f o r marine and non-marine p r e s e n t day oceans o r on landmasses.

d e p o s i t s , whether l o c a t e d i n

The p a l y g o r s k i t e L a t e C r e t a c e o u s -

Paleocene "event" of C a l l e n (1978, see a l s o S i n g e r , 1980) h a s been r e s o l v e d i n t o s e v e r a l e v e n t s , one of which (Campanian) is e s s e n t i a l l y o c e a n i c , and t h e importance of three earlier i n t e r v a l s o f d e p o s i t i o n i s recognized.

25

TABLE I

Major I n t e r v a l s of Abundance

DSDP

'LAND'

Cambrian Devonian Permian

-

-

Carboniferous Triassic

Late C r e t a c e o u s , e s p e c i a l l y Albian and Campanian L a t e C r e t a c e o u s t o Eocene ( e s p e c i a l l y Eocene). Eocene, e s p e c i a l l y E a r l y and L a t e Late O l i g o c e n e t o Middle Miocene

Late O l i g o c e n e to Middle Miocene, e s p e c i a l l y Middle Miocene

Pliocene t o P l e i s t o c e n e

Pliocene t o P l e i s t o c e n e

V E I N DEPOSITS Vein o c c u r r e n c e s are p l o t t e d i n F i g .

14.

M o s t are a s s o c i a t e d w i t h

basalts, serpentinites or other related basic r o c k s , and a r e g e n e r a l l y r e g a r d e d as h y d r o t h e r m a l i n o r i g i n .

The age of most

is d i f f i c u l t to e s t a b l i s h , and l i t t l e i n f o r m a t i o n is g i v e n a b o u t o v e r l y i n g rocks. e t al.

The s t u d i e s of Watts ( 1 9 8 0 ) , Haranczyk and Prochazka ( 1 9 7 4 ) and Barnes ( 1 9 7 8 ) s u g g e s t t h a t some c o u l d be t h e r e s u l t of w e a t h e r i n g or

p e d o g e n e s i s i n a high-Mg2+ environment,

s u c h as f a v o u r e d by Muller-Vonmoos

and

Schindler (1973) i n a d e p o s i t i n Switzerland. Occurrences i n caves a r e also informative.

Such d e p o s i t s , f o r example

those d e s c r i b e d by Lowry (1964) and Urbani (1975 l i m e s t o n e , w i t h p a l y g o r s k i t e c o a t i n g s on calcite

are j o i n t i n f i l l i n g s i n The former i s i n E a r l y t o

Middle O l i g o c e n e s h e l f l i m e s t o n e of n o r t h e r n N e w Zealand and i s t h o u g h t t o have been d e p o s i t e d under p h r e a t i c c o n d i t i o n s .

The d e p o s i t d e s c r i b e d by

Urbani i s i n l a t e J u r a s s i c d o l o m i t e o f Venezuela and w a s d e r i v e d by w e a t h e r i n g of t h e c a r b o n a t e .

Both p l o t w i t h i n the same l a t i t u d i n a l p o s i t i o n as

s e d i m e n t a r y d e p o s i t s o f t h e i r age. I t i s n e c e s s a r y t o i n v e s t i g a t e whether or n o t t h e p r e s e n c e of t h e v e i n s i n d i c a t e s t h e p r e s e n c e of s e d i m e n t a r y

26 p a l y g o r s k i t e i n t h e h o s t rocks.

It is suggested that o t h e r vein d e p o s i t s

could a l s o be t h e r e s u l t of r e c o n s t i t u t i o n of p a l y g o r s k i t e s from s u r r o u n d i n g rocks,

and t h i s a l s o needs to be t e s t e d by s u i t a b l e a n a l y s e s .

A number of o c c u r r e n c e s

are o f undoubted h y d r o t h e r m a l o r i g i n , w i t h

s u i t a b l y zoned c r y s t a l l i z a t i o n s e q u e n c e s , i n c r a c k s r e l a t e d to i g n e o u s b o d i e s

or hydrothemal v e i n s .

PALY GORSKITES "VEIN" DEPOSITS

I 82-25 I

SADME

1 Y uo

180"

0"

90"

180"

F i g . 14. Vein d e p o s i t s , p l o t t e d on p r e s e n t day map. FD = f a l c o n d i t e . See a p p e n d i x 1 1 . 4 r e f e r e n c e s .

D I SCUSSICN Latitudinal Distribution --_-----------__________ The l a t i t u d i n a l d i s t r i b u t i o n of p a l y g o r s k i t e s w i t h i n the p r e s e n t c o n t i n e n t a l areas

(e.

between 20-40°N

and S ) i s u n l i k e l y t o be t h e r e s u l t o f

b i a s e d s a m p l i n g , though the n a t u r e of that s a m p l i n g p r e c l u d e s r i g o r o u s

statistical t e s t i n g .

I n t h e n o r t h e r n hemisphere, e x t e n s i v e s t u d i e s o f c l a y s

from r o c k s of a l l a g e s have been made by the d e v e l o p e d n a t i o n s e x i s t i n g i n these regions.

The e x t e n t o f l a n d a t l a t i t u d e s greater t h a n 4OoN is g r e a t ,

and y e t v e r y few p a l y g o r s k i t e d i s c o v e r i e s ( a p a r t f r o m vein d e p o s i t s : compare Fig.

1 4 w i t h F i g s 1 a n d 10-12) have been made i n r o c k s younger t h a n

Triassic.

Thus the ' l a n d ' d e p o s i t s (as a g a i n s t

DSDP d e p o s i t s )

are

27 l a t i t u d i n a l l y c o n t r o l l e d f o r the younger d e p o s i t s and are t h o u g h t to r e f l e c t

past mild climatic ' a r i d i t y ' .

I t is u n c e r t a i n what t y p e of a r i d i t y i s

i n v o l v e d , though a climate similar t o t h a t of s o u t h e r n S o u t h A u s t r a l i a , M e d i t e r r a n e a n to s e m i - a r i d

&.

type, is l i k e l y .

The e x i s t e n c e of a c l i m a t i c b e l t conducive t o p a l y g o r s k i t e f o r m a t i o n i s i n d i c a t e d by e v e n t s i n A u s t r a l i a and I n d i a .

F i g u r e s 10-11 show t h a t a s

A u s t r a l i a d r i f t s n o r t h w a r d s p a l y g o r s k i t e s are d e p o s i t e d , f i r s t l y i n t h e n o r t h d u r i n g t h e O l i g o c e n e and t h e n i n s o u t h e r n A u s t r a l i a n i n t h e Miocene. S i m i l a r l y d e p o s i t i o n does n o t b e g i n i n I n d i a u n t i l t h e L a t e C r e t a c e o u s t o E a r l y Eocene, when it had d r i f t e d i n t o l a t i t u d e 2OoS (see Powell e t a l . , f o r d e t a i l s of the northward d r i f t of A u s t r a l i a and I n d i a ) .

1981,

However t h e

s i t u a t i o n i n I n d i a i s c o m p l i c a t e d by a s s o c i a t i o n w i t h b a s a l t s , and p o s s i b i l i t y of h y d r o t h e r m a l a d d i t i o n of Mg2+. The c o n c l u s i o n i s t h a t t h e climate of t h e Late C r e t a c e o u s was ' a r i d ' , which c o r r e s p o n d s w i t h t h e o b s e r v a t i o n s o f F r a k e s ( 1 9 7 9 ) . C a r b o n i f e r o u s and Eocene -re a c c e p t e d views.

That t h e

also ' a r i d ' i s i n some c o n f l i c t w i t h p r e s e n t l y

Perhaps ' a r i d i t y '

may have been a g r e a t e r f a c t o r i n c e r t a i n

l a t i t u d e s a t t h e s e times t h a n has g e n e r a l l y been a c c e p t e d , p a r t i c u l a r l y f o r t h e s o u t h e r n hemisphere.

Some of t h e major Devonian-Carboniferous

deposits i n

n o r t h e r n R u s s i a may r e p r e s e n t d e e p sea h y d r o t h e r m a l d e p o s i t s a s s o c i a t e d w i t h

basalts, t h u s n o t b e i n g connected w i t h p a r t i c u l a r c l i m a t i c c o n d i t i o n s . The r e s u l t s of t h e Deep Sea D r i l l i n g P r o j e c t s u g g e s t p a l y g o r s k i t e s are probably f a i r l y u n i f o r m l y d i s t r i b u t e d i n t h e o c e a n s , and d o n o t r e f l e c t t h e l a t i t u d i n a l c o n s t r a i n t s a p p a r e n t i n t h e Neogene. palygorskite-bearing

d i s t r i b u t i o n of a l l h o l e s d r i l l e d .

t o 110 M a .

The d i s t r i b u t i o n of

DSDP h o l e s i s v i r t u a l l y t h e same as t h e o v e r a l l T h i s a p p l i e s f o r a l l t i m e i n t e r v a l s back

P l o t t i n g t h e h i g h e s t c o n c e n t r a t i o n of p a l y g o r s k i t e r a t h e r t h a n

s i m p l y i t s p r e s e n c e o r a b s e n c e p r o d u c e s t h e same r e s u l t ( F i g . 3C), e x c e p t t h a t t h e r e i s a somewhat more e x c e p t i o n a l c o n c e n t r a t i o n i n t h e 0-20' w i t h t h e 20-40°

belt.

b e l t compared

I n s p e c t i o n of t h e p l o t s shows that it i s t h e n o r t h

I n d i a n Ocean, Red Sea and P a c i f i c Ocean d e p o s i t s t h a t have t h e g r e a t e s t i n f l u e n c e on t h i s , r a t h e r t h a n t h e M e d i t e r r a n e a n and p r o t o - A t l a n t i c S e a s . Thus t h e dominant ocean o c c u r r e n c e s are n o t d i s t r i b u t e d i n t h e same l a t i t u d e s

as t h e ' l a n d ' d e p o s i t s .

The e v a p o r i t e - a s s o c i a t e d

p a l y g o r s k i t e s of the

Mediterranean and p r o t o - A t l a n t i c are, however i n t h e same l a t i t u d e s a s t h e peri-marine

'land'

deposits.

The i n i t i a l s u g g e s t i o n t h a t o c e a n i c d e p o s i t s w u l d r e f l e c t t h e z o n a t i o n a p p a r e n t on l a n d d u r i n g t h e Neogene i s n o t s u p p o r t e d by t h e d i s t r i b u t i o n

statistics.

I f most oceanic d e p o s i t s are d e t r i t a l , whether t h e y be d e p o s i t e d

from t u r b i d i t e s or from a e o l i a n d u s t , t h e n o c e a n c u r r e n t s have a p p a r e n t l y

28 produced a v e r y even r e d i s t r i b u t i o n .

Although g e o l o g i c a l e v i d e n c e i n t h e

d e p o s i t s themselves s t r o n g l y s u g g e s t s many are d e r i v e d from land d e p o s i t s , o r formed i n n e a r s h o r e s h a l l o w marine o r l a g o o n a l environments, a d i f f e r e n t o r i g i n f o r many o t h e r s must be proposed t o a c c o u n t f o r t h e d i s t r i b u t i o n statistics. Such i s s u g g e s t e d f o r some of t h e major d e p o s i t s , R i s e i n t h e P a c i f i c Ocean ( F i g 7 ) .

f o r example t h e Shatsky

These d e p o s i t s are n o t i n t u r b i d i t e s , and

t h e r e were no l a r g e ' l a n d ' d e p o s i t s nor s u i t a b l e p e r i m a r i n e environments known around t h e margins of t h e p r o t o - P a c i f i c Ocean t o a c t as a d e t r i t a l s o u r c e . Even if such s o u r c e s f o r t h e s e d e p o s i t s were found i n t h e f u t u r e , t h e d i s t a n c e of t h e S h a t s k y R i s e from land i s such t h a t one would have t o e n t e r t a i n a d i f f e r e n t s p r e a d i n g h i s t o r y (Woods and Davies, 19821, or e a r t h expansion s i n c e t h e Campanian ( S h i e l d s , 1 9 7 9 ) , to a c c o u n t f o r t h e i r p r e s e n t p o s i t i o n . Gorbunova (1972, 1 9 7 3 , ) h a s s u g g e s t e d t h e y a r e hydrothermal, a h y p o t h e s i s s u p p o r t e d by t h e oxygen isotope s t u d i e s of Church and Velde ( 1 9 7 9 ) . An a l t e r n a t i v e

i s t h e d i a g e n e s i s of m o n t m o r i l l o n i t e and r e l a t e d m i n e r a l s ,

s u g g e s t e d by Couture ( 1 9 7 7 a ) . d i f f i c u l t , however,

Conversion o f smectite to p a l y g o r s k i t e i s

though Giresse e t a 1 ( 1 9 8 0 ) p r o p o s e it f o r p r o d u c t i o n of

p a l y g o r s k i t e i n t h e P a r i s b a s i n , from b e i d e l l i t e .

The c r y s t a l l i n i t y and

a g g r e g a t i o n of p a l y g o r s k i t e f i b r e s i n t o bundles was i n v e s t i g a t e d by S i n g e r ( 1 9 8 1 ) f o r t h e Jordan r i f t v a l l e y d e p o s i t s .

H e found p a l y g o r s k i t e w a s

d i s c r e t e , w i t h no s i g n s of t r a n s i t i o n t o m o n t m o r i l l o n i t e ,

i n d i c a t i n g it was

n o t d e r i v e d from t h e l a t t e r m i n e r a l b u t w a s p r o b a b l y a d i r e c t p r e c i p i t a t e from solution. The r e c e n t d i s c o v e r i n g of abundant p a l y g o r s k i t e i n t h e Marianas Trench, a forearc basin, i s of considerable i n t e r e s t .

D e s p r a i r i e s (1982) and Natland

and Mahoney ( 1 9 8 2 ) p r e s e n t s t r o n g e v i d e n c e f o r a hydrothermal s o u r c e of Mg2+, and massive a l t e r a t i o n of b a s a l t i c g l a s s , v o l c a n o c l a s t i c sediments and b e i d i l l i t e clays.

The Mg2+ w a s d e r i v e d from p r o c e s s e s a s s o c i a t e d w i t h t h e

earlier b a s a l t i c o u t p o u r i n g s .

The p r o c e s s i s similar to t h a t s u g g e s t e d by

Russian w r k e r s (Gorbunova, 1973, Kurnusov and Shevchenko, 19821, f o r o t h e r l a r g e o c c u r r e n c e s i n t h e P a c i f i c Ocean.

This d e m o n s t r a t e s t h a t marine

d e p o s i t s of d e e p o c e a n i c o r i g i n c a n be d e r i v e d from processes independent of l a t i t u d i n a l constraints. A n a l y s i s of a e o l i a n components i n t h e c e n t r a l P a c i f i c Ocean ( R e a and Jancock, 1981) r e v e a l t h e Aptian/Albian c o n t r i b u t i o n h e r e w a s e s s e n t i a l l y v o l c a n i c d u s t ; and show the Coniacean and L a t e Campanian were t i m e s of l o w a e o l i a n i n p u t froni the land.

This r e i n f o r c e s t h e i d e a o f an e s s e n t i a l l y

d i a g e n e t i c o r i g i n f o r the Campanian p a l y g o r s k i t e peak, and a l s o s u g g e s t s it

w a s n o t d e r i v e d from v o l c a n i c d u s t .

The o t h e r e v i d e n c e from t h i s s t u d y d o e s

29

n o t s u p p o r t a windblown c a l c a r e o u s d u s t o r i g i n f o r P a c i f i c p a l y g o r s k i t e i n t h e A p t i a n / A l b i a n and Coniacean.

T h i s i s d e s p i t e t h e f a c t t h a t t h e s e were a n o x i c

e v e n t s i n t h e o c e a n s , when c a r b o n a c e o u s matter was h i g h . form r e a d i l y i n t h e p r e s e n c e of o r g a n i c matter.

P a l y g o r s k i t e s do n o t

This i s compatible with

formation a t a l a t e r s t a g e through d i a g e n e s i s o r

palygorski te-sepiolite a 1t e r a t i o n .

Agewise d i s t r i b u t i o n The DSDP r e s u l t s s u g g e s t a broad a g e w i s e c o i n c i d e n c e w i t h ' l a n d ' deposits,

though t h e main Campanian peak i s l a r g e l y an o c e a n i c f e a t u r e .

the four 'land'

d e p o s i t s r e c o r d e d i n t h e Campanian-Maastrichtian,

Of

o n l y one i s

d e f i n i t e l y o f t h i s age. The a g e w i s e l i n k f o r o t h e r t i m e s of p a l y g o r s k i t e abundance c a n be e x p l a i n e d by t h e i n f l u x o f d e t r i t a l p a l y g o r s k i t e s t o t h e o c e a n s d u r i n g ' a r i d '

times,

i n t h e manner d e s c r i b e d e l s e w h e r e i n this p a p e r , supplemented by I f o c e a n i c d e p o s i t s c o u l d be more c l e a r l y i d e n t i f i e d a s d e t r i t a l ,

diagenesis.

d i a g e n e t i c or h y d r o t h e r m a l , and t h e r e s u l t s p l o t t e d , t h e age d i s t r i b u t i o n might prove d i f f e r e n t f o r each t y p e . I n the s e a r c h f o r g o s s i b l e e x p l a n a t i o n s of t h e a p p a r e n t agewise l i n k , C a l l e n ( 1 9 7 8 ) s u g g e s t e d Mg2+ i n t r o d u c e d t h r o u g h v o l c a n i s m c o u l d be a c o n t r i b u t i n g f a c t o r , though t h e r e i s no o b v i o u s c o r r e l a t i o n between v o l c a n i c e f f u s i v e p h a s e s ( f i g . 7, Ronov e t a l . ,

1980) and p a l y g o r s k i t e ' e v e n t s ' .

There

i s an a p p r o x i m a t e c o r r e l a t i o n of p a l y g o r s k i t e ' e v e n t s ' w i t h the a l p i n o t y p e o r o g e n i c e v e n t s o f Schwan (19801, e x c e p t f o r t h e Campanian phase.

This

i m p l i e s v o l c a n i c d u s t i n t h e oceans is n o t n e c e s s a r i l y a p r e c u r s o r f o r p a l y g o r s k i t e ; i n t r o d u c t i o n of hydrothermal Mg2+ the continental deposits, d u s t or b a s a l t s .

r i c h solutions is likely.

t h e r e i s f r e q u e n t l y no s o u r c e of Mg2+

In

from v o l c a n i c

D e p o s i t s l i k e t h o s e o f t h e Miocene i n South A u s t r a l i a

( C a l l e n , 1 9 7 7 ) have no l i n k t o r o c k s of this k i n d .

A similar problem e x i s t s

i n t h e s o u t h e a s t of t h e S t a t e of South A u s t r a l i a , where t h e e x t e n s i v e d o l o m i t e s of t h e modern and a n c i e n t "Coorong" e n v i r o n m e n t s (Muir e t a l . , 19801, and t h e p a l y g o r s k i t e s of t h e calcretes ( H u t t o n and Dixon,

1981) and

modern s o i l s (Turchenek and Oades, t h i s volume) need more t h a n a series of i s o l a t e d b a s a l t i c volcanoes ( M t . groundwa ters

.

Gambier, etc.) to p r o v i d e Mg2+ i o n s i n t h e

Lack of p a l y g o r s k i t e s i n c e r t a i n i n t e r v a l s i n t h e oceans, e s p e c i a l l y the Maastrichtian

-

E a r l y P a l e o c e n e and E a r l y O l i g o c e n e , i s p a r t l y a r e f l e c t i o n of

climatic c o n d i t i o n s .

These were t i m e s of w i d e s p r e a d l o w s e d i m e n t a t i o n rates

and a b u n d a n t h i a t u s . e s (Moore e t a l . ,

1978, Worsley and D a v i e s , 1 9 7 9 ) ,

30

connected t o c i r c u l a t i o n of c o l d ocean c u r r e n t s .

Such c u r r e n t s are u n l i k e l y

to a f f e c t s h e l f s e d i m e n t a t i o n and o b v i o u s l y n o t non-marine

sedimentation, b u t

t h e e v e n t s which g e n e r a t e d them may do so. The abundance of p a l y g o r s k i t e s i n n e a r s h o r e marine environments i m p l i e s peaks i n c o n c e n t r a t i o n might c o i n c i d e w i t h t h e s p r e a d of e p e i r i c seas.

Ronov

e t a l . ( 1980) summarized world sediment volumes i n g e o s y n c l i n e s and s h e l v e s , s e d i m e n t a t i o n rates, and o t h e r f a c t o r s of r e l e v a n c e .

Comparing t h e s e r e s u l t s

t h e r e i s no o b v i o u s correspondence between peaks i n p a l y g o r s k i t e s e d i m e n t a t i o n , r e g r e s s i o n s and t r a n s g r e s s i o n s , or e x t e n t of seas and platforms.

The main peak i n abundance i n t h e Campanian i s t h e o n l y one which

correlates w i t h a major i n t e r v a l of s h e l f s e d i m e n t a t i o n and e x t e n t , and y e t most d e p o s i t s o f t h i s t i m e are o c e a n i c .

I

Jenkyns ( F i g . 3, 1980) p l o t s g l o b a l t r a n s g r e s s i o n c u r v e s .

These do show

a c r u d e correspondence between t r a n s g r e s s i o n s and p a l y g o r s k i t e peaks, more p r e c i s e l y j u s t b e f o r e and a f t e r t h e maximum t r a n s g r e s s i v e phase of t h e Santonian

- Coniacean.

However, most of t h e p a l y g o r s k i t e s o f t h e s e times were

forming i n t h e open oceans, n o t i n e p i c o n t i n e n t a l seas.

More d e t a i l e d

s t u d i e s , such a s t h o s e of Cooper (1977) are u n h e l p f u l as t h e age r a n g e s o f p a l y g o r s k i t e peaks are n o t known w i t h enough accuracy.

The g e n e r a l l a c k of

c o r r e l a t i o n i n d i c a t e s t h a t o t h e r f a c t o r s are more i m p o r t a n t t h a n t h e e x t e n t o f e p e i r i c seas.

The p r e v a l e n c e of

'aridity'

within the continents a t these

times may be one such f a c t o r .

(i)

Late P l i o c e n e to Holocene p a l y g o r s k i t e - s e p i o l i t e

l o c a t e d mainly between 20°-40°N

and 1 0°-350S

M e d i t e r r a n e a n t o a r i d climatic belts.

m i n e r a l d e p o s i t s are

latitudes in the

Oceanic d e p o s i t s of these

t i m e s are probably l a r g e l y d e r i v e d from windblown d u s t , w i t h some slumped material and t u r b i d i t e s .

Neoformation took p l a c e e x t e n s i v e l y

i n c a l c a r e o u s s o i l s and pedogenic c a l c r e t e s , and minor p l a y a s and springs. ( i i ) The l a t i t u d i n a l p a t t e r n i n t h e Pliocene-Holocene t h r o u g h o u t t h e Cretaceous and T e r t i a r y . between 30°-400N

and South.

is present

C o n c e n t r a t i o n is l a r g e l y

That p a r t of the d i s t r i b u t i o n

c o n t r i b u t e d by t h e oceans, d e r i v e d from DSDP r e s u l t s , i s e s s e n t i a l l y c o i n c i d e n t a l with t h a t determined from onshore d e p o s i t s , b u t i s t h e r e s u l t of i n i t i a l sample d i s t r i b u t i o n and c a n n o t t h e r e f o r e be used as s u p p o r t f o r a l a t i t u d i n a l d i s t r i b u t i o n i n t h e oceans.

31 P r i o r t o t h e C r e t a c e o u s , t h e m a j o r i t y of d e p o s i t s are i n t h e n o r t h e r n hemisphere, w i t h i n l a t i t u d e 4S0, the equator.

b u t are most abundant n e a r

P r e - J u r a s s i c c o n t i n e n t a l r e c o n s t r u c t i o n s are somewhat

s p e c u k a t i v e and n o t independent of s e d i m e n t a r y environmental d a t a . ( i i i )P a l y g o r s k i t e - s e p i o l i t e

m i n e r a l s i n p e r i m a r i n e and i n t r a c o n t i n e n t a l

s i t u a t i o n s are i n d i c a t o r s of semi-arid or s e a s o n a l l y a r i d c o n d i t i o n s , b u t n o t g e n e r a l l y a s extreme a s f o r sand dune d e s e r t formation and This i s i n d i c a t e d by t h e l a t e Neogene

evaporite deposition.

d i s t r i b u t i o n , p a r t i a l c o i n c i d e n c e i n l a t i t u d i n a l and agewise d i s t r i b u t i o n between marine and non-marine C a i n o z o i c , and the l i t h o f a c i e s associates.

deposi t s during t he D e p o s i t i o n took p l a c e i n

b r a c k i s h a l k a l i n e waters. (iv)

Some c o n t i n e n t a l l a c u s t r i n e d e p o s i t s , such a s t h e e x t e n s i v e A u s t r a l i a n o c c u r r e n c e s , are n o t a s s o c i a t e d with v o l c a n i c a s h , n o r w e r e there any basic r o c k s or metamorphic r o c k s of any e x t e n t i n t h e

s u r r o u n d i n g catchments.

Such d e p o s i t s d e m o n s t r a t e o t h e r s o u r c e s o f

magnesium i o n s are s u f f i c i e n t f o r palyqorskite-sepiolite g e n e s i s ( i n t h e South A u s t r a l i a n b a s i n s f o r example, t h e o n l y o t h e r s o u r c e are t h e e x t e n s i v e m o n t m o r i l l o n i t i c c l a y s of t h e C r e t a c e o u s ) . (v)

S e v e r a l l a r g e deep ocean d e p o s i t s have a hydrothermal o r i g i n , which b e s t e x p l a i n s t h e Campanian peak i n t h e P a c i f i c Ocean, similar p r o c e s s e s may e x p l a i n some o f t h e l a r g e P a l a e o z o i c d e p o s i t s o f northern Russia, a s s o c i a t e d with b a s a l t s .

A l t e r a t i o n could have

o c c u r r e d some t i m e a f t e r d e p o s i t i o n , which might e x p l a i n t h e r a t h e r poor c o r r e l a t i o n w i t h worldwide c l i m a t i c and t e c t o n i c e v e n t s . O t h e r s were d e r i v e d from s o i l s t h r o u g h windblown d u s t i n t h e t r a d e wind belts, and from n e a r s h o r e o c c u r r e n c e s by slumping and turbidity currents.

Some r e p r e s e n t foundered peri-marine

environments l e f t behind as t h e c o n t i n e n t s d r i f t e d a p a r t . There i s no r e l a t i o n s h i p between p d y ~ s k i t e - ~ p i o l i t e d e p o s i t i o n and water d e p t h i n t h e oceans. (vi)

Vein d e p o s i t s are m o s t l y hydrothermal i n o r i g i n , and are c h a r a c t e r i z e d by a p r e v a l e n c e o f s e p i o l i t e and r e l a t e d m i n e r a l s . Some are p r o b a b l y pedogenic c r a c k or j o i n t i n f i l l s , some from s p r i n g a c t i o n , or r e s u l t from t h e w e a t h e r i n g of a l t e r a t i o n zones around ore b o d i e s and igneous rocks.

( v i i ) P e r i o d s when p a l y g o r s k i t e - s e p i o l i t e are: Cambrian L a t e Devonian and C a r b o n i f e r o u s

group m i n e r a l s are m o s t abundant

32

L a t e Permian and T r i a s s i c

?Late Jurassic Late Cretaceous,

e s p e c i a l l y A l b i a n , Campanian and p o s s i b l y

Coniacian. E a r l y Eocene ( F i r s t major widespread non marine d e p o s i t s ) L a t e Eocene L a t e Oligocene Middle Miocene t o P l i o c e n e

ACKNOWLEDGEMENTS The d a t a a r e p r e s e n t e d w i t h t h e p e r m i s s i o n of t h e D i r e c t o r G e n e r a l of The m a n u s c r i p t w a s r e a d by B. G.

Mines and Energy, South A u s t r a l i a . and G .

W.

K r i e g , W.V.

P r e i s s i s s i n c e r e l y thanked f o r t r a n s l a t i o n of German

and R u s s i a n l i t e r a t u r e , t o which D.

Gravestock h a s a l s o c o n t r i b u t e d .

C a l l e n h a s t r a n s l a t e d French l i t e r a t u r e .

bibliography.

( l i b r a r i a n ) was i n v a l u a b l e f o r

A l l b u t J.H.C.

J.H.

T h i s p a p e r m u l d have been

i m p o s s i b l e t o produce w i t h o u t t h e i r g e n e r o u s h e l p . McKellar-Stewart+

Forbes

The a s s i s t a n c e of N. c o m p i l a t i o n of t h e e x t e n s i v e

(my w i f e ) are of t h e Dept.

of Mines and Energy,

South A u s t r a l i a . Correspondence w i t h A.

S i n g e r (Hebrew U n i v e r s i t y , J e r u s a l e m ) , C. Weaver

( G e o r g i a I n s t i t u t e of Technology, U.S.A.), U t v i n n i n g s a v d e l i n g e n , Norway) and R. U.S.A.)

L.

Watts (Norske S h e l l ,

Couture (Argonne N a t i o n a l L a b o r a t o r y ,

i s acknowledged.

L i l i a n Musich, S c r i p p s I n s t i t u t e of Oceanography, La J o l l a , C a l i f o r n i a i s thanked f o r p r i n t o u t s o f p a l y q o r s k i t e a n a l y s e s n o t i n DSDP volumes ( c u r r e n t t o

1978). A.

S i n g e r and two unknown r e f e r e e s are thanked f o r r e v i e w i n g this

manuscript.

Angeli ( S . A u s t . k p t . Mines thanked for typing this offset. Miss F. de

& m rgy) is

Sincerely

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39

O R I G I N AN0 GEOLOGIC IMPLICATIONS OF THE PALYGORSKITE DEPOSITS OF S.E. STATES

UNITED

CHARLES E. WEAVER Georgia I n s t i t u t e o f Technology ABSTRACT

This paper i s a p a r t i a l summary of a d e t a i l e d i n v e s t i g a t i o n of t h e Miocene of t h e S.E.

U n i t e d States by Weaver and Beck (1977).

P a l y g o r s k i t e formed i n

shallow s c h i z o h a l i n e lagoons, l a r g e l y by t h e a l t e r a t i o n of m o n t m o r i l l o n i t e . The temporal ' d i s t r i b u t i o n of p a l y g o r s k i t e seems c o n t r o l l e d l a r g e l y by c l i m a t e which i n t u r n i s r e l a t e d t o t h e p a t t e r n of c o n t i n e n t a l d r i f t . GEOLOGIC SETTING The Miocene sediments of t h e southeastern United States c o n t a i n commerci a1 deposits of p a l y g o r s k i t e - s e p i o l i t e and phosphate.

These minerals, i n a d d i t i o

t o carbonates, o p a l - c r i s t o b a l i t e , z e o l i t e , and some of t h e smectites, had an orthochemical o r i g i n . The m i n e r a l s were deposited i n a peri-marine environment where c o n d i t i o n s favored t h e growth of m i n e r a l s f r o m s o l u t i o n . Sediments were deposited i n shallow water i n a m i l d l y t e c t o n i c a l l y a c t i v e hinge area separating t h e A t l a n t i c Ocean and t h e Gulf of Mexico.

An isopoch

map of t h e Miocene and Upper Oligocene Tampa Formation ( F i g u r e 1) shows t h e major s t r u c t u r a l f e a t u r e s i n t h e area.

M o n t m o r i l l o n i t e i s t h e dominant c l a y

mineral i n t h e T e r t i a r y o f t h e A t l a n t i c and Gulf Coastal P l a i n s except f o r t h e Upper Oligocene and Lower and Middle Miocene of n o r t h e r n F l o r i d a , Georgia, southern South Carol i na, Georgia Shelf and B1ake P1atdau, where p a l y g o r s k i t e and s e p i o l i t e are commnly dominant.

A marine channel o r trough extended through southern Georgia and connected t h e A t l a n t i c Ocean and t h e Gulf o f Mexico f r o m Cretaceous through Oligocene time. The F l o r i d a p l a t f o r m was an i s l a n d . During t h e Miocene t h e platform was j o i n e d w i t h t h e mainland.

During l a t e Oligocene (Tampa) t h e sea t r a n s -

gressed over an eroded k a r s t l a n d s u r f a c e and t i d a l and l a c u s t r i n e carbonates ( l a r g e l y dolomite) and p a l y g o r s k i t e were deposited.

This i s t h e f i r s t

occurrence of p a l y g o r s k i t e and s e p i o l i t e i n t h e area. General t r a n s g r e s s i o n continued d u r i n g much o f t h e Lower Miocene (Torreya and Chipola) f o l l o w e d by a r e g r e s s i o n c u l m i n a t i n g i n t h e development of an extensive s o i l and reworked ( c l a y , phosphate and quartz pebbles) h o r i z o n near During t h e Lower

t h e end of Lower Miocene and t h e beginning o f Middle Miocene.

Miocene p a l y g o r s k i t e and s e p i o l i t e formed throughout t h e r e g i o n i n b r a c k i s h Formation of these c l a y s ceased a t t h e end of lagoon and t i d a l environments. t h e Lower Miocene ( a t a s o i l -reworked horizon).

40

LATERAL PATTERN F i g u r e 2 i s a c r o s s - s e c t i o n i n t h e n o r t h e r n p a r t of t h e area, p a r a l l e l i n g t h e Savannah River.

P a l y g o r s k i t e and s e p i o l i t e are r e s t r i c t e d t o Lower

Miocene and stop a b r u p t l y a t t h e Middle-Lower Miocene boundary.

Numerous o t h e r

cross-sections show t h a t t h e bedded p a l y g o r s k i t e i s r e s t r i c t e d t o t h e Lower Miocene and Tampa.

The Middle Miocene sediments are c h a r a c t e r i z e d by t h e

Fig. 1. Generalized Miocene paleogeographic map based on thickness o f Miocene. Two p o s i t i v e areas separated by two depocenters. The Suwannee U p l i f t i s an o l d e r f e a t u r e than t h e Ocala U p l i f t . The A t l a n t i c and Appalachicola Embayments were i n t e r m i t t e n t l y connected by a trough.

41 presence o f m a r i n e diatoms and o p a l - c r i s t o b a l i t e ( F i g u r e 3).

Phosphate pebbles

a r e c o n c e n t r a t e d a t t h e Lower-Middle Miocene boundary and mark t h e b e g i n n i n g of t h e M i d d l e Miocene t r a n s g r e s s i o n .

T h i s boundary, c h a r a c t e r i z e d by phosphate

and c l a y pebbles, c a n b e t r a c e d o v e r much of t h e area.

T h i s i s t h e p e r i o d of

t i m e when much of' t h e phosphate was c o n c e n t r a t e d i n t h e c o a s t a l area. F i g u r e 4 i s a s o u t h w e s t - n o r t h e a s t c r o s s - s e c t i o n down t h e c e n t e r of t h e Trough.

P a l y g o r s k i t e is p r e s e n t i n t h e Upper Oligocene and Lower Miocene.

The commercial p a l y g o r s k i t e c l a y beds o c c u r i n b o t h t h e Lower Miocene and Middle Miocene sediments ( s o u t h e r n p a r t of s e c t i o n ) .

The l a t t e r d e p o s i t s a r e

d e t r i t a l and 'were d e r i v e d f r o m t h e Lower Miocene d e p o s i t s .

Fig. 2. Northwest-southeast c r o s s - s e c t i o n a l o n g t h e Savannah R i v e r e x t e n d i n g 80 km t o t h e coast. The M i d d l e Miocene-Lower Miocene boundary c o i n c i d e s w i t h t h e change f r o m m o n t m o r i l l o n i t e (M) t o p a l y g o r s k i t e p l u s s e p i o l i t e (P and S). K = k a o l i n i t e , z = z e o l i t e , B = b i o t i t e , 0 = no samples, b l a c k c i r c l e s = phosphate pebbles, open c i r c l e s = c l a y c l a s t s .

42

The general lithologic units of t h e Lower Miocene are shown in Figure 5. Coarse, high energy, gravelly deposits occur in the center of the Atlantic Embayment. These were deposited in an estuarine environment a t the m o u t h of t h e ancestral Altamaha and Sewanee Rivers. The deposits are flanked by shallow brackish dolomite (limpid variety) and dolomitic palygorskite beds. Relatively pure clay beds occur t o the northwest of the Ocala High and extend t o the southwest. The environment was shallow water marine t o brackish.

B PL

C L A Y MI NERALOG Y

x

f

L

-

0 0

te

iL -S

Fig. 3. Core hole Effingham No. 3 showing lithology, mineralogy and phosphate content. I = i l l i t e ; B = b i o t i t e ; K = kaolinite; M = montmorillonite; P = palygorskite; S = s e p i o l i t e ; P.M. = post Miocene; and BPL = bone phosphate of lime. Core also shown i n Figure 2.

43

The d i s t r i b u t i o n of p a l y g o r s k i t e and s e p i o l i t e i n t h e Lower Miocene i s q u i t e extensive ( F i g u r e 6).

S e p i o l i t e i s concentrated shoreward of t h e p a l y g o r s k i t e

and was apparently formed under l e s s s a l i n e c o n d i t i o n s .

The A t l a n t i c Embayment

and Trough c o n t a i n d e t r i t a l p a l y g o r s k i t e . Thin, r e l a t i v e l y pure p a l y g o r s k i t e c l a y beds, 1 t o 5 m t h i c k , a r e concent r a t e d i n an area from s l i g h t l y n o r t h of t h e Georgia-Florida border t o 60 km t o t h e south of t h e s t a t e l i n e .

S i m i l a r beds are present i n o t h e r areas b u t have

not been mined. The main commercial i n t e r v a l commonly c o n t a i n s two c l a y beds separated by a sand, s h e l l , dolomite, o r s o i l bed of v a r i a b l e thickness.

These two c l a y beds

appear t o be r e l a t i v e l y continuous throughout t h e n o r t h F l o r i d a area of t h e Trough.

Thin, discontinuous beds occur above and below t h e main c l a y h o r i z o n

b u t they g e n e r a l l y c o n t a i n abundant m o n t m o r i l l o n i t e .

Fig. 4. Southwest-northeast ( r i g h t ) c r o s s - s e c t i o n extending f r o m northwest F l o r i d a through Embayment and Trough t o Savannah River. Section shows d i s t r i b u t i o n of c l a y minerals. White areas i n lower p a r t of s e c t i o n i n d i c a t e no data; i n t h e upper p a r t of s e c t i o n w h i t e i n d i c a t e s where k a o l i n i t e i s t h e predominant clay. Authigenic Lower Miocene commercial c l a y beds occur between sections W6890 and 665494; d e t r i t a l Middle Miocene commercial c l a y beds between GGS205 and 665175. S t i p p l e = p a l y g o r s k i t e , h o r i z o n t a l = montmoril l o n i t e .

44 VERTICAL PATTERN L i t h o l ogy A c o r e ( 9 m) from t h e La Camelia p a l y g o r s k t e mine

Engel h a r d M i n e r a l s and

Chemical Corp.) i n n o r t h F l o r i d a was s t u d i e d i n d e t a i l t o d e t e r m i n e t h e v e r t i c a l v a r i a b i l i t y and t h e r e l a t i o n s of t h e v a r i o u s parameters.

The s t r u c t u r a l ,

t e x t u r a l , m i n e r a l o g i c a l and chemical d a t a i n d i c a t e t h e r e a r e two m a j o r d e p o s i t i o n a l cycles represented within t h e minable i n t e r v a l .

The sediments d e p o s i t e d

d u r i n g t h e two c y c l e s d i f f e r i n d e t a i l b u t i n g e n e r a l a r e s i m i l a r .

The

environments of d e p o s i t i o n grade f r i m s h a l l o w m a r i n e t o l a g o o n a l t o t i d a l f l a t t o soil. F i g u r e 7 shows t h e c o r e l i t h o l o g y and c l a y m i n e r a l c o m p o s i t i o n .

There a r e

t w o p u r e c l a y beds (0.5 t o 1.5 m and 6.0 t o 7.3 m) t h a t c o n s i s t of r e l a t i v e l y pure, p a r a l l e l l a m i n a t e d c l a y .

The c l a y beds were d e p o s i t e d d u r i n g two p e r i o d s

o f r e g r e s s i o n s e p a r a t e d by a p e r i o d of t r a n s g r e s s i o n . The l o w e r i n t e r v a l s t a r t s w i t h a c l a y e y sand.

T h i s i s f o l l o w e d by a t h i n

i n t e r v a l o f mud-cracked c l a y i n f i l l e d w i t h a c o a r s e r sandy c l a y . c l a s t s a r e p a r t i a l l y dolomitized.

Some of t h e

There i s a t h i n sand zone i n t h e m i d d l e of

t h e c l a y bed and some worm burrows n e a r t h e top.

F i g . 5. D i s t r i b u t i o n of m a j o r l i t h o l o g i c u n i t s i n t h e Lower Miocene. Mixed a r e a t o t h e southwest c o n t a i n s beds of p a l y g o r s k i t e b u t o v e r a l l l i t h o l o g y i s complex. P a l y g o r s k i t e i s m a j o r c l a y i n t h e d o l o m i t i c sediments. The High F o r o r i e n t a t i o n see F i g u r e 1. ( O c a l a ) was an a r e a of non-deposition.

45

This i s followed by another bed of mud-cracked and s l i g h t l y reworked clay c l a s t s in a matrix of c o a r s e r sandy clay. Round sand-size clay grains a r e a l s o abundant in t h i s bed. This bed i s overlain by a sandy clay bed with a v e r t i c a l , s l i g h t l y slickensided f r a c t u r e pattern. Many f r a c t u r e s a r e coated with a t h i n f i l m o f glossy clay t h a t resembles cutans (clay skins) found i n s o i l . The lower half contains organic s t a i n s and clay g r a i n s and the upper half burrows. This interval i s a soil zone which occurs a t t h e top of a sequence of sediments deposited during a regression. This interval i s overlain by a sandy bed which i s a greenish clayey sand with i r r e g u l a r mottles of white sand and worm tubes. Over t h i s i s a white sand containing pelecypod s h e l l s . The mixing i n the lower p a r t of the sand is apparently due t o both burrowing and c u r r e n t action.

PALVGORSIITE

LOWER MIOCENE C L A Y S

20 K Y

Fig. 6. Map showing d i s t r i b u t i o n of palygorskite and s e p i o l i t e i n the Lower Miocene. Montmorillonite i s t h e dominant clay in unlabeled areas. Dotted l i n e indicates l o c a t i o n of concentration of d e t r i t a l palygorskite in Middle Miocene sediments. For o r i e n t a t i o n see Figure 1.

46

There i s a gradual t r a n s i t i o n from sand t o dolomitic clay ( 3 m). A pure clay bed containing patches of dolomite extends up t o 2.4 m. Dolomite then becomes predominant and t h e r e i s 0.9 m of clayey dolomite. The dolomitic bed i s overlain by 1 m of pure clay. The lower one-third has an i r r e g u l a r , massive appearance with some i r e g u l a r v e r t i c a l f r a c t u r e surf aces. This clay bed grades i n t o an interval which c o n s i s t s l a r g e l y of t h e same type of c l a y , b u t i s heavily burrowed and i t i f i l l e d w i t h a coarser clayey sand. This i s the top o f the core. I t i s overlain by a clayey marine sand s i m i l a r t o t h e type t h a t occurs in t h e burrows in t h e top of t h e core. WLVGORSKITE

Meters

MONTMORILLDNITE

SEPIOLITE

Marine Clay Burrowed

Lagoona I

TI do I

Marine Sand

Sail

Supra Tidal

Lagoona I

Tidal Marine Sand

Fig. 7. Lithology and mineralogy of MC-1 core from La Camelia Mine, Florida. Two cycles of regression and transgression a r e evident.

47

Thus, on gross l i t h o l o g y , t h e r e appear t o be two s i m i l a r , b u t d i s t i n c t depositional u n i t s .

Both u n i t s appear t o b e topped by a h i a t u s , and b o t h s t a r t

w i t h a sand bed of p r o b a b l y m a r i n e ( l i t t o r a l ) o r i g i n .

The l o w e r u n i t i s

c h a r a c t e r i z e d by mud c r a c k e d and l o c a l l y reworked sediments and t h e upper u n i t by d o l o m i t i c beds. The t e x t u r a l d a t a i n d i c a t e t h e l a g o o n a l p a l y g o r s k i t e c l a y s c o n t a i n l e s s t h a n

10%sand and have a mean g r a i n s i z e (MZ) l e s s t h a n 3.04.

Marine m o n t m o r i l l o n i t e

c l a y s and c l a y e y sands c o n t a i n more t h a n 30% sand and t h e MZ i n c r e a s e s as t h e percent sand increases.

Reworked samples and s o i l samples have i n t e r m e d i a t e

values. Mineralogy P a l y g o r s k i t e i s t h e predominant c l a y i n t h e s e c t i o n .

Montmorillonite i s

I l l i t e and mica a r e p r e s e n t i n second i n abundance, f o l l o w e d by s e p i o l i t e . .The e s t i m a t e d r e l a t i v e c l a y m i n e r a l

minor amounts t h r o u g h o u t t h e s e c t i o n .

content, based on x - r a y p a t t e r n s o f o r i e n t e d s l i d e s , i s shown i n F i g u r e 7. The c l a y m i n e r a l s u i t e i s c l o s e l y r e l a t e d t o t h e l i t h o l o g y and t h u s presumably d e p o s i t i o n a l environments.

I n addition, there are s i g n i f i c a n t

d i f f e r e n c e s between t h e upper and l o w e r d e p o s i t i o n a l u n i t s . I n t h e p e b b l y zone ( 6 t o 5 m) t h e pebbles have a h i g h p a l y g o r s k i t e c o n t e n t . The c l a y e y sand m a t r i x i s composed l a r g e l y o f m o n t m o r i l l o n i t e ( F i g u r e 7).

Small

(2 t o 5 mn) rounded t a n c l a y g r a i n s a r e s i m i l a r i n c o m p o s i t i o n t o t h e l a r g e S e p i o l i t e i s present throughout t h i s

blocks o f apparent mud-crack o r i g i n .

i n t e r v a l i n t h e c l a y pebbles and g r a i n s b u t n o t i n t h e m a t r i x .

The c l a y s u i t e

o f t h e m a t r i x i s s i m i l a r t o t h a t of t h e o v e r l y i n g m o n t m o r i l l o n i t i c sandy s o i l . M o n t m o r i l l o n i t e comprises o v e r 90% o f t h e c l a y s u i t e i n t h e s o i l zone. S e p i o l i t e has a maximum c o n c e n t r a t i o n a t t h e b o t t o m of t h e s o i l zone and i s n o t present i n t h e o v e r l y i n g sediments.

This i s t h e only i n t e r v a l t h a t contains

more s e p i o l i t e t h a n p a l y g o r s k i t e .

A d e t a i l e d s t u d y o f t h e b o t t o m p a r t of t h e s o i l zone i n d i c a t e s t h a t t h e c l a y m i n e r a l s a r e inhomogeneously d i s t r i b u t e d .

The g r e e n i s h sandy c l a y i s composed

almost e n t i r e l y o f m o n t m o r i l l o n i t e , w i t h some b i o t i t e .

Some small w h i t e

pebbles have a c o m p o s i t i o n s i m i l a r t o t h e u n d e r l y i n g l a r g e pebbles (palygorskite

>

montmorillonite

>

sepiolite).

A l s o p r e s e n t a r e some small

t a n n i s h g r a i n s ( 2 t o 5 mn) and a t h i n t a n n i s h c o a t i n g on t h e v e r t i c a l f r a c t u r e surfaces.

I n b o t h of t h e s e t y p e s of samples m o n t m o r i l l o n i t e i s t h e dominant

c l a y and s e p i o l i t e i s more abundant t h a n p a l y g o r s k i t e . s u i t e has a d i s t i n c t i v e occurrence.

Thus t h e " s e p i o l i t e - r i c h "

The d i s t r i b u t i o n suggests t h e c l a y may be

secondary and has formed by p o s t - d e p o s i t i o n a l s o i l i n t e r v a l and growth i n t h e bottom.

l e a c h i n g of t h e upper p a r t of t h e

48

Tannish g r a i n s i n t h e upper p o r t i o n of t h e s o i l zone a r e composed almost e n t i r e l y o f p a l y g o r s k i t e , sometimes w i t h d o l o m i t e .

These g r a i n s must have been

added f r o m a d j a c e n t o v e r l y i n g sediments. Burrows i n t h e 4 t o 4.8 m m o n t m o r i l l o n i t e - r i c h i n t e r v a l a r e f i l l e d by p a l y g o r s k i t e , i n d i c a t i n g c l a y has been worked down f r o m as much as 1.5 m above. I n t h e o v e r l y i n g s h e l l y sand zone p a l y g o r s k i t e i n c r e a s e s and becomes r e l a t i v e l y abundant w i t h i n t h e sand.

However, t h e m o t t l e s and p e b b l e s of

g r e e n i s h c l a y e y sand i n t h i s i n t e r v a l have a h i g h m o n t m o r i l l o n i t e c o n t e n t s i m i l a r t o t h a t of t h e underlying i n t e r v a l .

Thus some o f t h e m i x i n g i s p r o b a b l y

due t o c u r r e n t r e w o r k i n g o f t h e l o w e r m a t e r i a l i n t o t h e upper, r a t h e r t h a n b u r r o w i n g which would cause a downward m i x i n g .

The l a r g e s h e l l s i n t h i s

i n t e r v a l (3.3 t o 3.6 m) have been c o n v e r t e d t o d o l o m i t e and much o f t h e p a l y g o r s k i t e i s secondary. upper c l a y bed.

P a l y g o r s k i t e i s a t a maximum (90%) i n t h e d o l o m i t e and

There i s a s l i g h t decrease i n p a l y g o r s k i t e i n t h e c l a y s of t h e

uppermost burrowed zone.

The burrows a r e f i l l e d w i t h a sandy m o n t m o r i l l o n i t e

clay derived from t h e overlying montmorillonite. Texture TEM and SEM p i c t u r e s show a number of i n t e r e s t i n g f e a t u r e s .

S h o r t , 1 pm

f i b e r s comprise t h e bulk o f t h e p a l y g o r s k i t e - s e p i o l i t e clay b u t long ( g r e a t e r t h a n 10 pm) f i b e r s a r e l o c a l l y abundant.

Long f i b e r s o c c u r i n s m a l l areas w i t h

d e s i c c a t i o n f e a t u r e s , i n d i c a t i n g t h e y grew f r o m r e s i d u a l f l u i d s when d e h y d r a t i o n was n e a r l y complete.

These o c c u r i n a m a t r i x of s h o r t f i b e r s .

Long f i b e r s o c c u r i n t h e s o i l samples where t h e y f o r m mats and a r e a l s o aligned perpendicular t o v e i n walls. S h o r t f i b e r s were observed f o r m i n g f r o m m o n t m o r i l l o n i t e , r e p l a c i n g q u a r t z and c a l c i t e f o s s i l s , and by t h e c o a l e s c i n g o f s m a l l o p a l i n e spheres.

Much o f

t h e c l a y o c c u r s as t h i n , p a r a l l e l laminae, s u g g e s t i n g a p e r i o d i c s u p p l y o f d e t r i t u s ( m o n t m o r i l l o n i t e ) t o t h e lagoon. Environment

I t i s e v i d e n t from t h e s t u d y o f t h i s one c o r e (and many o t h e r s ) t h a t t h e s e Miocene sediments were d e p o s i t e d i n a s h a l l o w w a t e r environment near t h e s t r a n d 1i n e . I n g e n e r a l t h e m o n t m o r i l l o n i t i c sandy i n t e r v a l s appear t o be o f s h a l l o w marine o r i g i n .

The h o r i z o n t a l -bedded, c l a y - r i c h p a l y g o r s k i t e beds must have

been d e p o s i t e d i n a q u i e t lagoon.

The d o l o m i t i c beds were d e p o s i t e d i n a simi,

l a r environment, though some i s replacement d o l o m i t e and p r o b a b l y formed e p i g e n e t i c a l ly. The p e b b l e and mud-crack beds r e p r e s e n t l a g o o n a l d e p o s i t s t h a t were l a t e r reworked by c u r r e n t s coming f r o m e i t h e r t h e seaward o r landward d i r e c t i o n .

The

v e r t i c a l l y - o r i e n t e d m o n t m o r i l l o n i t i c , o r g a n i c , sandy c l a y bed i s a s o i l f o r m e d

49

on f l u v i a t i l e sediments.

Burrowing i s evident throughout, b u t i s p a r t i c u l a r l y

i m p o r t a n t i n t h e sediments c l o s i n g t h e end o f each d e p o s i t i o n a l c y c l e . The d e p o s i t i o n a l c y c l e s s t a r t e d o f f w i t h a sand o r sandy s h e l l bed which acted as b a r r i e r s . thin barriers.

S h a l l o w w a t e r lagoons developed b e h i n d t h e s e r e l a t i v e l y

I n t h e o l d e r c y c l e t h e lagoon was sometimes evaporated t o n e a r

dryness and mud c r a c k s developed.

D u r i n g t h e e a r l y s t a g e t h e b a r r i e r was

breached and c l a y e y m a r i n e sands were mixed w i t h t h e mud c l a s t s . seemed t o b e c h a r a c t e r i s t i c o f t h e l o w e r d e p o s i t i o n a l u n i t .

Near t h e end

This s i t u a t i o n

o f t h e c y c l e f r e s h w a t e r c u r r e n t s p r o b a b l y d i d t h e reworking.

This lower u n i t i s

topped by a s o i l zone developed on f l u v i a t i l e sediments, s u g g e s t i n g t h e o v e r a l l u n i t i s regressive.

T h i s r e g r e s s i o n i s f o l l o w e d by an a b r u p t t r a n s g r e s s i o n

( s h e l l y m a r i n e sand) which m i g h t r e f l e c t o n l y a m i n o r l a t e r a l s h i f t of environments. The upper d e p o s i t i o n a l u n i t shows l i t t l e r e w o r k i n g and a r e l a t i v e l y t h i c k lagoonal sequence ( d o l o m i t e and p a l y g o r s k i t e c l a y bed), which suggest a more permanent b a r r i e r p l u s a decrease i n a v a i l a b l e S i and A l .

This i n t e r v a l

appears t o end i n a s h a l l o w i n g r e g r e s s i v e environment (burrows and r e w o r k i n g )

,

f o l l o w e d by a r e l a t i v e l y a b r u p t m a r i n e t r a n s g r e s s i o n . Thus, b o t h d e p o s i t i o n a l u n i t s appear t o r e p r e s e n t a seaward m i g r a t i o n of a shallow water f l u v i a t i l e - l a g o o n - b a r r i e r

sequence.

Whenever t h e m i g r a t i o n was

i n t e r r u p t e d by a s u s t a i n e d m a r i n e t r a n s g r e s s i o n a new c y c l e began. The l i t h o l o g y i n d i c a t e s t h a t t h e l o w e r u n i t was p r o b a b l y more e f f e c t e d by p h y s i c a l energy ( c l a y c l a s t ) and t h e upper by chemical energy ( d o l o m i t e ) .

The

d e t a i l e d m i n e r a l and chemical d i f f e r e n c e s between t h e two u n i t s l i k e l y r e f l e c t o n l y m i n o r e n v i r o n m e n t a l and s o u r c e d i f f e r e n c e s ; however, f r o m a p r a c t i c a l s t a n d p o i n t t h e s e d i f f e r e n c e s can b e used t o i d e n t i f y t h e d i f f e r e n t c l a y beds. The presence of l i m p i d d o l o m i t e , f a u n a l data, l o w L i c o n t e n t (average 24 ppm) and l a c k o f h y p e r s a l i n e f e a t u r e s suggests t h e w a t e r i n t h e lagoons was b r a c k i s h , probably schizohaline.

The presence of m o n t m o r i l l o n i t e i n b o t h m a r i n e and

c o n t i n e n t a l sediments i n d i c a t e s i t was p r o b a b l y a l s o p r e s e n t i n t h e s h a l l o w w a t e r lagoons.

Chemistry F i g u r e 8 shows t h e d i s t r i b u t i o n o f A1203, MgO and Fe203 i n t h e c l a y f r a c t i o n o f t h e MC-1 core.

I n g e n e r a l t h e A1203 and MgO a r e i n v e r s e l y r e l a t e d and

r e f l e c t v a r i a t i o n s i n t h e m o n t m o r i l l o n i t e ( A l ) and p a l y g o r s k i t e (Mg) c o n t e n t . Fe203 f o l l o w s A1203 and has a maximum v a l u e n e a r t h e base of t h e s o i l zone where

i t was a p p a r e n t l y c o n c e n t r a t e d by o r g a n i c l e a c h i n g o f t h e s o i l .

The K20 (mica)

values (0.5 t o 1.7%) c l o s e l y f o l l o w A1203. Chemical a n a l y s e s and s t r u c t u r a l f o r m u l a ( T a b l e 1 ) o f p u r e m i n e r a l concent r a t e s i n d i c a t e t h e m a r i n e m o n t m o r i l l o n i t e s have a r e l a t i v e l y u n i f o r m

50

Meters

-

0-

I-

2-

3-

4-

D L

0 5-

6-

7-

8-

Fig. 8. Mine.

L

Chemical data of c l a y f r a c t i o n of samples from MC-1 core, La Camelia

composition.

The s o i l smectite has a r e l a t i v e l y high content of Fe and Mg.

Approximately h a l f t h e octahedral p o s i t i o n s of t h e p a l y g o r s k i t e are occupied by Al.

I f i t i s assumed t h a t t h e p a l y g o r s k i t e i n p a l y g o r s k i t e

+ smectite mixtures

has t h e same composition as pure p a l y g o r s k i t e , t h e composition of t h e smectite

(Si02 = 68.3%. Fe20j = 7.4%, MgO = 2 4 . X ) i s more s i m i l a r t o s t e v e n s i t e than t o montmorillonite. Chemical c a l c u l a t i o n s tend t o confirm t h a t most of t h e palyg o r s k i t e formed by t h e d i r e c t a l t e r a t i o n of montmoril l o n i t e w i t h s t e v e n s i t e - l i k e

51

Table 1.

S t r u c t u r a l Formula.

MONTMORILLONITE Marine Soil EC-2-32 F5-13 FF-1 FH-12 FF-18 Octahedral A1 Fe3+ Mg

z

PALYGORSKITE FE-21

FE-17

1.49

1.43

1.46

1.51

1.24

1.66

1.58

.24 .28 2.01

.33 .25 2.01

.28 .28 2.02

.25 .22 1.98

.42 .41 2.07

.36 1.83 3.85

.40 1.79 3.77

.ll 3.89

-11 3.89

.03 3.97

.ll 3.89

.19 7.81

.40 7.60

.01 .45

.24 .40

Tetrahedral A1 .09 Si 3.91 Exchange Cations Ca Na

MIXED FF-54'

MC1-S3 ~ C 1 - 2 3 ~

.79

1.20

1.32

1.33

.55 2.23 3.57

.38 2.15 3.73

.43 2.08 3.83

.38 2.01 3.72

.47 7.53

-39 7.61

.36 7.64

.53 .39

.31 .39

.52 .17

FE-80' Octahedral A1 Fe3+ Mg

c

Tetrahedral .71 A1 Si 7.29 Exchange Cations Ca .57 Na .20 1. 2. 3. 4.

P>Sp>M P >> M P >> M,Qtz P >> M

material being a by-product. The A1 and Fe remained constant and a d d i t i o n a l S i , Mg and H were obtained f r o m s o l u t i o n . When t h e S i and Mg content of t h e solut i o n i s s u f f i c i e n t l y h i g h and t h e pH i s i n t h e range of 8 t o 9 m o n t m o r i l l o n i t e w i l l convert t o p a l y g o r s k i t e . When montmoril l o n i t e i s not present s e p i o l i t e

w i l l precipitate.

Dolomite i s commonly formed contemporaneously w i t h both C a l c i t e i s commonly deposited o u t of phase w i t h t h e

s e p i o l i t e and p a l y g o r s k i t e . Mg minerals.

Though most of t h e p a l y g o r s k i t e formed by d i r e c t replacement of

mantmorillonite, i t i s evident f r o m t h e c o n f i g u r a t i o n t h a t some of t h e long f i b e r p a l y g o r s k i t e grew f r o m s o l u t i o n ( F i g u r e 9).

The l a t t e r t y p e i s most

commonly found i n areas where voids probably existed. DOLOMITE Shells i n sands u n d e r l y i n g t h e lagoonal c l a y have been replaced by p a l y g o r s k i t e and dolomite.

Seeping Mg-rich waters f r o m t h e lagoon e s t a b l i s h e d

F i g . 9. P a l y g o r s k i t e t r e e a s s o c i a t e d w i t h d o l o m i t i c s h e l l (3.4 m i n F i g u r e 7 ) White b a r equals 1 pm.

53

a d o l o m i t i z a t i o n gradient.

The deepest s h e l l s a r e c o n v e r t e d t o d o l o m i t e ( p r o t o -

d o l o m i t e ) p r e s e r v i n g t h e p l a t e t e x t u r e of t h e c a l c i t e . r i c h i n Ca r e l a t i v e t o t h e i n t e r i o r .

The o u t e r s u r f a c e s a r e

T h i s i s t r u e of most of t h e dolomites.

Once t h e p l a t e s achieve a p r o t o d o l o m i t e c o m p o s i t i o n , g r o w t h s t a r t s a t t h e edges and two- and t h r e e - s i d e d rhombs and e v e n t u a l l y s i x - s i d e d h o l l o w rhombs a r e formed ( v e r t i c a l sequence).

P l a t e s arranged i n v a r i o u s s u b s p h e r i c a l f o r m s a r e

present i n some d o l o m i t e l e n s e s and beds.

D o l o m i t e rhombs i n t h e c l a y beds have

o v e r l a p p i n g , t h i n , f l ame-shaped l a y e r s s u g g e s t i n g a slow sheet-by-sheet growth r a t h e r t h a n replacement o r a b r u p t p r e c i p i t a t i o n .

D o l o m i t e f o r m a t i o n precedes

p a l y g o r s k i t e i h some s i t u a t i o n s and f o l l o w s i n o t h e r s .

I n some areas i t appears

t h a t m o n t m o r i l l o n i t e r e a c t s w i t h d o l o m i t e o r Mg c a l c i t e t o f o r m p a l y g o r s k i t e and c a l c i t e ( f i n e disks). OETRITAL DEPOSITS The commercial c l a y d e p o s i t s 40 km n o r t h e a s t of t h e s e p r i m a r y d e p o s i t s were d e p o s i t e d i n t h e narrow M i d d l e Miocene Trough on t o p of t h e s o i l zone s e p a r a t i n g t h e Lower and M i d d l e Miocene.

Diatoms and sponge s p i c u l e s , p r e s e n t i n amounts

up t o 30%, i n d i c a t e a r e s t r i c t e d m a r i n e environment becoming m r e m a r i n e t o t h e n o r t h e a s t (seaward).

The p a l y g o r s k i t e and s e p i o l i t e ( 2 0 t o 70% of t h e c l a y

s u i t e ) i s d e t r i t a l and d e r i v e d from Lower Miocene c l a y s on t h e f l a n k o f t h e u p l i f t e d Ocala High ( t o t h e e a s t and s o u t h e a s t ) . t a i n i n g a p p r e c i a b l e a p a t i t e a r e abundant.

Clay g r a i n s and pebbles con-

T h i s c l a y i s o v e r l a i n by b r a c k i s h

w a t e r ( d i a t o m s ) , m o n t m o r i l l o n i t i c c l a y and sand ( K - f e l d s p a r ) d e r i v e d f r o m t h e west f l a n k and d e p o s i t e d d u r i n g t h e f i n a l m a r i n e r e g r e s s i o n i n t h e area. The p a l y g o r s k i t e - s e p i o l i t e c l a y ( F i g u r e 10) o c c u r s as l e n s e s (10 t o 50 f e e t t h i c k ) and were d e p o s i t e d i n s h e l t e r e d depressions between Lower Miocene b a r r i e r i s l a n d , beach, and c h e n i e r sand r i d g e s when t h e a r e a was t r a n s g r e s s e d by t h e M i d d l e Miocene seas.

The d e p o s i t s a r e r e s t r i c t e d t o t h e southwest p o r t i o n of

t h e Trough w h i c h e x i s t e d as a s i l l .

The s i l l e f f e c t was produced by t h e u p l i f t

o f t h e f l a n k i n g Ocala High; t h i s u p l i f t a l s o a f f o r d e d t h e p a l y g o r s k i t e s e p i o l i t e source.

F a r t h e r t o t h e n o r t h e a s t t h e Trough deepens and

m o n t m o r i l l o n i t i c c l a y s were deposited. There i s a c o m p l e t e c o m p o s i t i o n a l g r a d u a t i o n between c l a y pebbles and phosp h a t e pebbles.

During periods of weathering a p a t i t e replaces a d d i t i o n a l c l a y

and d i a t o m s i n t h e pebbles.

Most o f t h e a p a t i t e o c c u r s as s h o r t r o d s b u t t h a t

r e p l a c i n g diatoms has shapes r a n g i n g f r o m s p h e r i c a l t o p r i s m a t i c c r y s t a l s . O p a l - c r i s t o b a l i t e formed f r o m d i s s o l v e d diatoms and sponge s p i c u l e s i s r e l a t i v e l y abundant.

I t i s commonly massive b u t o c c u r s as b l a d e d s p h e r u l e s

and we1 1 -rounded o p a l ine spheres.

54

STABILITY RELATIONSHIPS Thermodynamic c a l c u l a t i o n s (25°C) have been made f o r t h r e e r e a c t i o n s of d i r e c t concern: montmorillonite-palygorskite, palygorskite-aqueous s o l u t i o n , and sepiolite-aqueous s o l u t i o n .

The s t a b i l i t y f i e l d boundaries f o r these r e a c t i o n s

a r e d e f i n e d by: l o g [Mg++] + 2 pH + 2 l o g [H,SiO;]

+ 0.76 pH + 2.6 l o g [ H 4 S i O i l t 0.62 l o g [ A l ( O H ) i I = -10.70,

0.69 l o g [Mg"]

+2

l o g [Mg"]

= 5.75,

respectively.

pH + 1.5 l o g [H4SiOi]:

and

= 7.95,

I n a l l cases t h e c h a i n s i l i c a t e s are f a v o r e d by an increase i n

one o r more of [Mg

++1,

pH, and CH4SiO;l.

P a l y g o r s k i t e also r e q u i r e s an appro-

p r i a t e i n p u t of A1 (and Fe), e i t h e r i n h e r i t e d d i r e c t l y from t h e precursor c l a y o r taken f r o m s o l u t i o n .

Sepiolite requires l o g [H4SiOi]

B

C

A

_ . ... . .

.

6 0

-. . . .. .. .

, ..

.

. -.

.

. _ .

. . ..

'

= 4.25

(around 3.0

ppm

0

. . . . . ..I ._ ... ' . . . . . , .1 . . ._' . . .. . .. .- . . . . _ . . ,_ . . . . . .- . _. .- . . ' .

MONTMORILLON IT€

0

0

a W n

orskite and Sepiolile

'

i'

'

CHEROKEE CO.

MINE

Fig. 10. North-south l i n e of s e c t i o n ( 4 c o r e s ) through Cherokee Company Mine, NW Thomay County, Georgia. Lower t a n sand u n i t i s Lower Miocene sand w i t h s o i l zone. O v e r l a i n by Middle Miocene, d e t r i t a l p a l y g o r s k i t e c l a y bed, a. m o n t m o r i l l o n i t e c l a y bed, and a m o n t m o r i l l o n i t e sand. Both c o n t a i n marine diatoms and sponge spicules.

55

Si02 i n

sea

w a t e r , assuming H4SiO:

aqueous s o l u t i o n . l o g [H,SiOi]

1. -4.29

= 1.13) f o r s t a b i l i t y w i t h r e s p e c t t o

P a l y g o r s k i t e should f o r m f r o m m o n t m o r i l l o n i t e a t ( a r o u n d 2.7 ppm S i 0 2 ) .

Thus, f r o m t h e p o i n t of view of

thermodynamic c a l c u l a t i o n s , o n l y s l i g h t m o d i f i c a t i o n s of normal sea w a t e r c o n d i t i o n s a r e r e q u i r e d t o f o r m s e p i o l i t e and p a l y g o r s k i t e .

However, i f t h i s were

t r u e t h e s e m i n e r a l s s h o u l d be more common. The c a l c u l a t i o n s i n d i c a t e t h e c h a i n s i l i c a t e s a r e f a v o u r e d by an i n c r e a s e i n [Mg"],

pH, and [ H 4 S i O i ] .

F i e l d o b s e r v a t i o n s i n d i c a t e they a r e a l s o f a v o r e d by

l e s s t h a n normal s a l i n i t y and by h i g h temperature. C a l c u l a t e d s t a b i l i t y f i e l d b o u n d a r i e s between p a l y g o r s k i t e , m o n t m o r i l l o n i t e , and a s e r i e s of d i f f e r e n t c o r r e n s i t e s ( F i g u r e ll), show t h a t r e g a r d l e s s of t h e c h o i c e o f c o r r e n s i t e c o m p o s i t i o n , i t i s f a v o r e d o v e r m o n t m o r i l l o n i t e by h i g h e r [Mg"]

The [ H 4 S i O i l e f f e c t i s m i n o r .

and pH.

r e a c t i o n t h e i m p o r t a n c e o f [Mg++] c o r r e n s i t e composition. gorskite.

For t h e corrensite-palygorskite

and pH i s v a r i a b l e depending on t h e c h o i c e of

However, i n a l l cases h i g h [ H 4 S i O i l f a v o r s p a l y -

These c a l c u l a t i o n s t e n d t o c o n f i r m t h e i d e a t h a t c o r r e n s i t e i s more

-6

-5

-4

-3

-2

log H SiOo [ 4 41

F i g . 11. S t a b i l i t y r e l a t i o n s among s i m p l i f i e d ( F e - f r e e ) p a l y g o r s k i t e and m o n t m o r i l l o n i t e and v a r i o u s c o r r e n s i t e s a t 2 5 T . Continuous l i n e s ( " i d e a l " c o r r e n s i t e ; dashed l i n e s (----------), B r a d l e y and Weaver c o r r e n s i t e ; d o t t e d l i n e s (. .), h y p o t h e t i c a l c o r r e n s i t e .

....

1,

56 abundant i n t h e P a l e o z o i c and e a r l y Mesozoic because e v a p o r a t i c environments w i t h h i g h pH were abundant. TEMPORAL FACTORS Small e v o l u t i o n a r y o r p e r i o d i c f l u c t u a t i o n s i n t h e c o m p o s i t i o n of t h e ocean may have i n c r e a s e d t h e p o s s i b i l i t y o f M g - s i l i c a t e v e r s u s Mg-carbonate f o r m a t i o n

i n t h e younger Phanerozoic.

The f i r s t appearance o f p a l y g o r s k i t e i n t h e e a r l y

Mesozoic may b e r e l a t e d t o t h e i n i t i a t i n g o f sea f l o o r s p r e a d i n g and a t t e n d a n t i n t r o d u c t i o n of s i l i c a (and perhaps Mg) i n t o t h e oceans.

Development may have

been f u r t h e r enhanced i n t h e Upper CFetaceous by t h e p r o l i f e r a t i o n of diatoms. I n t h e G e o r g i a - F l o r i d a a r e a p a l y g o r s k i t e and l i m p i d d o l o m i t e developed i n s h a l l o w , c o a s t a l b r a c k i s h t o s c h i z o h a l i n e waters. h i g h pH.

Warm t e m p e r a t u r e caused a

Both i n c r e a s e d t h e s o l u b i l i t y o f , s i l i c a ( l a r g e l y f r o m d i a t o m s ) .

C o o l e r c o n d i t i o n s d u r i n g t h e M i d d l e Miocene made c o n d i t i o n s u n f a v o r a b l e f o r t h e development of p a l y g o r s k i t e .

Magnesium was o b t a i n e d f r o m sea water.

There i s a mutual a n t i p a t h y between p a l y g o r s k i t e and c l i n o p t i l o l i t e , w i t h p a l y g o r s k i t e b e i n g t h e f r e s h e r w a t e r m i n e r a l and c l i n o p t i l o l i t e t h e more s a l i n e equivalent.

The r e s u l t s of thermodynamic c a l c u l a t i o n s a r e c o m p a t i b l e w i t h t h i s

distribution. The phosphate d e p o s i t s a r e l a r g e l y r e s t r i c t e d t o t h e A t l a n t i c f a c i e s .

Much

o f t h e phosphate was p r o b a b l y d e r i v e d f r o m diatoms i n s h a l l o w c o a s t a l w a t e r s and c o n c e n t r a t e d by r e p l a c i n g c l a y pebbles and c l a y - r i c h f e c a l p e l l e t s .

A r e v i e w o f t h e l i t e r a t u r e on "marine" p a l y g o r s k i t e s i n d i c a t e s t h e r e i s l i t t l e , i f any, p o s i t i v e d a t a t o i n d i c a t e t h e y formed i n a normal m a r i n e environment.

P a l y g o r s k i t e i s r e l a t i v e l y abundant i n some deep sea cores.

Most

o f t h e d e s c r i p t i v e d a t a i n d i c a t e s i t i s d e t r i t a l o r hydrothermal i n o r i g i n .

It

i s suggested t h a t p e r i - m a r i n e p a l y g o r s k i t e d e p o s i t s f o r m o n l y i n b r a c k i s h w a t e r and m o n t m o r i l l o n i t e (and g l a u c o n i t e ) i s u s u a l l y t h e s t a b l e c l a y i n t h e normal m a r i n e waters.

C h l o r i t i c c l a y s (mixed-layer chlorite-montmoril l o n i t e ) are t h e

common s t a b l e phase under h y p e r s a l i n e c o n d i t i o n s . F i g u r e 12 shows t h e g e n e r a l d i s t r i b u t i o n of some a u t h i g e n i c m i n e r a l s t h r o u g h time.

C o r r e n s i t e and d o l o m i t e a r e abundant i n t h e P a l e o z o i c and e a r l y Mesozoic.

As Mg-rich c o r r e n s i t e decreases i n abundance M g - r i c h p a l y g o r s k i t e i n c r e a s e s i n abundance, as does k a o l i n i t e .

V a r i o u s s t u d i e s i n d i c a t e t h a t i n N o r t h America,

Europe and presumably N o r t h A f r i c a t h e P a l e o z o i c and E a r l y Mesozoic c l i m a t e was warmer and much d r i e r t h a n t o d a y ' s .

T h i s would f a v o r t h e development of evapo-

r i t i c c o n d i t i o n s , t h e c o n c e n t r a t i o n of Mg and t h e f o r m a t i o n of c o r r e n s i t e . B e g i n n i n g i n t h e L a t e Mesozoic, r a i n f a l l increased.

This increased r a i n f a l l

caused more i n t e n s e w e a t h e r i n g and t h e f o r m a t i o n of k a o l i n i t e .

I t apparently

a l s o c r e a t e d m r e b r a c k i s h w a t e r c o n d i t i o n s i n t h e f r i n g i n g m a r i n e environments. T h i s f a v o r e d t h e f o r m a t i o n of p a l y g o r s k i t e i n environments where c o r r e n s i t e formed i n d r i e r p e r i o d s .

57

TIME (MY.)

Fig. 12. Estimate of r e l a t i v e abundance of some authigenic minerals through a p o r t i o n of geologic time.

Coastal marine p a l y g o r s k i t e deposits range i n age from T r i a s s i c t o Miocene. Most deposits f r i n g e t h e Tethys and south A t l a n t i c Oceans.

Phosphate deposits

show a s i m i l a r d i s t r i b u t i o n and commonly are associated w i t h p a l y g o r s k i t e deposits.

Upwelling c o l d ocean waters are assumed t o be t h e source of t h e P;

i t would a l s o be a source of S i f o r t h e formation of palygorskite.

The temporal data suggest climate, t h a t i s , temperature and, possibly more important, humidity, determines whether o r n o t p a l y g o r s k i t e w i l l form.

The global d i s t r i b u t i o n of t h e major p a l y g o r s k i t e deposits i n d i c a t e s they are r e s t r i c t e d t o t h e b e l t of t r o p i c a l - s u b t r o p i c a l temperatures.

To a l a r g e extent

t h e d i s t r i b u t i o n was c o n t r o l l e d by t h e p a t t e r n of t h e warm Tethys currents. During t h e Mesozoic coastal p a l y g o r s k i t e was formed along t h e warm margins of t h e Tethys and South A t l a n t i c .

During t h e e a r l y Cenozoic t h e westward f l o w i n g

Tethys c u r r e n t s supplied warm waters t o t h e Caribbean region. The A f r i c a n and Eurasian p l a t e s converged i n t h e Late Oligocene and e a r l y Miocene and allowed these c u r r e n t s t o swing t o t h e n o r t h and increase temperatures i n t h e coastal waters of t h e southeastern United States, presumably c r e a t i n g t h e subtropical humid c o n d i t i o n s t h a t allowed p a l y g o r s k i t e t o form. The c o l l i s i o n of Europe and North A f r i c a a t G i b r a l t a r a t t h e beginning of t h e Middle Miocene modified t h e

58 A t l a n t i c c i r c u l a t i o n pattern, a l l o w i n g c o l d a r c t i c waters t o enter t h e western North A t l a n t i c .

T h i s caused a decrease i n t e m p e r a t u r e and h u m i d i t y and t h e

growth of p a l y g o r s k i t e ceased. i n t h e faunal s u i t e .

The i n c r e a s e d coolness

is c o n f i r m e d by a change

Low r a i n f a l l is i n d i c a t e d by t h e presence o f an abundance

o f opal p h y t o l i t h s c h a r a c t e r i s t i c o f p r a i r i e grasses. I n c o n c l u s i o n we contend t h a t c o a s t a l p a l y g o r s k i t e d e p o s i t s f o r m l a r g e l y f r o m rnontmoril l o n i t e i n p r o t e c t e d q u i e t w a t e r environments and under c l i m a t i c c o n d i t i o n s t h a t produce h i g h r a i n f a l l , b r a c k i s h w a t e r s and s u b t r o p i c a l temperatures. REFERENCE

Weaver, C. E. and Beck, K. C., 1977. Miocene of t h e S.E. U n i t e d S t a t e s : A model f o r chemical s e d i m e n t a t i o n i n a p e r i - m a r i n e environment, Sedimentary Geol., 17, 234 pp., and Developments i n Sedimentology, 22, E l s e v i e r , 234 pp.

59

THE CLAYS OF YUCATAN, M E X I C O :

A CONTRAST I N GENESIS

WAYNE C. ISPHORDING Department of Geology-Geography, U n i v e r s i t y o f South Alabama, Mobile, AL

36693

ABSTRACT The Yucatan P e n i n s u l a o f Mexico p r o v i d e s an e x c e l l e n t s i t e t o examine t h e formation of c l a y m i n e r a l s by pedogenic processes, d e t r i t a l s e d i m e n t a t i o n and direct crystallization.

Clays formed b y each o f these mechanisms a r e widespread

and can be found i n a l l s t a g e s o f m a t u r i t y , depending upon c l i m a t e and t h e geomorphic age o f t h e s i t e .

P o o r l y c r y s t a l l i z e d k a o l i n i t e , boehmite, t a l c and

c h l o r i t e c h a r a c t e r i z e t h e most y o u t h f u l c l a y s , whereas those i n an advanced stage o f m a t u r i t y c o n s i s t a l m o s t e n t i r e l y o f w e l l c r y s t a l l i z e d k a o l i n i t e . t r i t a l clays, i n contrast,

De-

a r e uncommon on t h e n o r t h e r n p e n i n s u l a , because o f

an almost complete l a c k o f s u r f a c e streams and, f o r t h e most p a r t , a r e r e s t r i c t e d t o t h e E a s t e r n B l o c k F a u l t D i s t r i c t and a number o f o l d b a s i n - l i k e areas.

S m e c t i t e c l a y s a r e abundant i n t h e s e b a s i n s and g i v e evidence o f h a v i n g

been d e p o s i t e d i n m a r g i n a l lagoons t h a t were l a t e r t r a n s f o r m e d i n t o s a l i n e lakes by t e c t o n i c u p l i f t .

The u l t i m a t e s o u r c e o f t h e d e t r i t a l m a t e r i a l appears

t o be r e l a t e d t o p y r o c l a s t i c d e b r i s c a r r i e d n o r t h w a r d f r o m B e l i z e and Guatemala. Tnlc, c : i l o r i t e ,

p a l y g o r s k i t e - s e p i o l i t e , and m i x e d - l a y e r k a o l i n i t e - m o n t m o r i l -

1!1niL? c w s t i t u t e t h e t h i r d g e n e r i c t y p e o f c l a y s found on t h e p e n i n s u l a and a l l a r e b e l i e v e d t o be r e l a t e d t o an o r i g i n b y d i r e c t c r y s t a l l i z a t i o n .

These

clays a r e e s s e n t i a l l y r e s t r i c t e d t o t h e n o r t h e r n r e g i o n o f t h e p e n i n s u l a and have c r y s t a l l i z e d e i t h e r d i r e c t l y f r o m m a r i n e w a t e r s o f e l e v a t e d s a l i n i t y o r have formed d i a g e n e t i c a l l y by a l t e r a t i o n o f d o l o m i t e . INTRODUCTION The Yucatan P e n i n s u l a o f Mexico extends n o r t h w a r d f r o m t h e Chiapas Laramide deformation b e l t o f C e n t r a l America and c o n s i s t s o f a massive c a r b o n a t e p l a t f o r m t h a t has, o n l y r e c e n t l y , p a r t i a l l y emerged f r o m t h e sea ( F i g . 1 ) .

The l i m e -

stones, d o l o m i t e s and e v a p o r i t e s t h a t c h a r a c t e r i z e t h e r e g i o n range i n age f r o m

Cretaceous t o Recent and a r e something o v e r 3,000 m e t e r s i n t h i c k n e s s near t h e northern shoreline.

Data f r o m deep w e l l s i n d i c a t e t h a t t h e carbonates r e s t

A detailed g e o l o g i c map o f t h i s 80,000 square k i l o m e t e r r e g i o n has y e t t o be compiled, non-conformably on a n d e s i t e s and metamorphics o f Pennsylvanian age.

however g e o l o g i c i n v e s t i g a t i o n s have i n c r e a s e d m a r k e d l y d u r i n g t h e p a s t 10 years as a d i r e c t consequence o f t h e r e q i o n ' s boom i n t o u r i s m .

The l a r q e

60

F i g . 1. Map o f t h e Yucatan P e n i n s u l a showing t h e m a j o r geomorphic ( p h y s i o graphic) provinces. number o f t o u r i s t s t h a t a n n u a l l y v i s i t t h e p e n i n s u l a have caused t h e government t o c o n s t r u c t numerous new r o a d s i n t o t h e i n t e r i o r w i t h t h e r e s u l t t h a t many exposures a r e now a c c e s s i b l e t h a t have h e l p e d c l a r i f y t h e r e g i o n a l geology.

A

number o f b a s i c g e o l o g i c q u e s t i o n s s t i l l r e m a i n t o be answered, however, and c o n t r o v e r s i e s abound i n t h e l i t e r a t u r e c o n c e r n i n g t h e p e n i n s u l a ' s s t r a t i g r a p h y , s t r u c t u r a l geology, and even t h e genesis o f i t s c l a y m i n e r a l s .

The l a t t e r i s

o f e s p e c i a l i n t e r e s t because, u n l i k e most o t h e r l o c a t i o n s i n t h e w o r l d where t h e r e s i d e n t c l a y s have formed d o m i n a n t l y by one s i n g l e process, t h o s e i n Yucatan f a l l i n t o t h r e e d i s t i n c t groups.

These i n c l u d e :

( 1 ) pedogenic c l a y s , ( 2 )

d e t r i t a l c l a y s , and ( 3 ) d i r e c t c r y s t a l l i z a t i o n ( " p r i m a r y " ) c l a y s .

Each o f

these has developed i n response t o a p a r t i c u l a r c o m b i n a t i o n o f c l i m a t i c , env i r o n m e n t a l and d i a g e n e t i c c o n d i t i o n s and, i n a g e n e r a l way, i s c h a r a c t e r i s t i c o f a p a r t i c u l a r area o f t h e peninsula.

61

PEDOGENIC CLAYS General D i s c u s s i o n With t h e exception o f smectite c l a y s found i n t h e eastern block f a u l t basins and i n s e v e r a l " p o l j e - l i k e "

basins i n t h e i n t e r i o r , c l a y s containing s i g n i f i -

c a n t d e t r i t a l components a r e e s s e n t i a l l y l a c k i n g elsewhere i n Yucatan.

North

o f t h e Champoton R i v e r a l l d r a i n a g e i s s u b t e r r a n e a n and, e x c l u d i n g a few t i d a l channels t h a t e x t e n d i n t o t h e Coastal Zone, s u r f a c e streams a r e c o m p l e t e l y lacking.

The s i m i l a r absence i n deep p e t r o l e u m t e s t w e l l s o f any i d e n t i f i a b l e

c l a s t i c s i n t e r b e d d e d w i t h t h e carbonates i n d i c a t e s t h a t such c o n d i t i o n s p e r s i s t e d t h r o u q h o u t t h i s r e g i o n from e a r l y T e r t i a r y t i m e .

Though c l a y s o r i g i n a t -

i n g by a l t e r a t i o n o f v o l c a n i c d e t r i t u s have n o t been u n e q u i v o c a l l y i d e n t i f i e d i n t h e n o r t h e r n p e n i n s u l a , u n - a l t e r e d ash i s d e s c r i b e d f r o m a t l e a s t one l o c a t i o n i n t h e Central H i l l D i s t r i c t ( a small lens, several centimeters thick, t h e Maya ceremonial cave a t L o l t u n ) .

Small amounts o f ash may, t h e r e f o r e ,

in

be

p r e s e n t as m i n o r components i n t h e s e s o i l s and i n t h e u n d e r l y i n g p a r e n t c a r bonate r o c k s . M i n e r a l o g y and Chemistry Quinones (1975) p r o v i d e d an e x c e l l e n t d e s c r i p t i o n o f s e v e r a l sol'l p r o f i l e s f r o m t h e n o r t h e r n p e n i n s u l a o f Yucatan and d e s c r i b e d two o f t h e more y o u t h f u l s o i l s as " O r t h i c U s t o c h r e p t s " and " O r t h i d i c H a p l u s t o l l s " , u s i n g t h e 1960 Comp r e h e n s i v e System t e r m i n o l o g y .

X-ray d i f f r a c t o g r a m s 1 t h r o u g h 4 ( F i g . 2 ) a r e

r e p r e s e n t a t i v e o f e a r l y pedogenic s o i l development and i n d i c a t e t h a t t h e s e s o i l s a r e l a r g e l y composed o f p o o r l y c r y s t a l l i z e d k a o l i n i t e , boehmite and t r a c e amounts o f t a l c and c h l o r i t e .

M i c r o s c o p i c e x a m i n a t i o n d i s c l o s e d t h a t most of

these s o i l s c o n s i s t e d l a r g e l y o f weathered l i m e s t o n e fragments, o r g a n i c d e b r i s , and l e s s e r amounts o f s o i l c l a y s and o x i d e s .

Quinones (1975) n o t e d t h a t if

i r o n o x i d e s were e l i m i n a t e d b y d i t h i o n a t e t r e a t m e n t , t h a t sand-sized p a r t i c l e s were p r a c t i c a l l y n o n - e x i s t e n t ( a l l s a n d - s i z e d p a r t i c l e s a r e e s s e n t i a l l y composed

o f i r o n o x i d e and h y d r o x i d e a g g r e g a t e s ) . F u r t h e r , though a l l o p h a n e was n o t i d e n t i f i e d i n any analyses performed by t h e a u t h o r , Quinones r e p o r t e d i t s l i k e l y presence as an amorphous s o i l c o n s t i t u e n t on t h e b a s i s o f p o s i t i v e sodium

fluoride tests.

I n view o f t h e f a c t t h a t amorphous i r o n o x i d e s were i d e n t i f i e d

by t h e w r i t e r as common c o n s t i t u e n t s o f t h e pedogenic s o i l s , i t seems l i k e l y t h a t amorphous forms o f aluminum s h o u l d a l s o be p r e s e n t . Chemical a n a l y s e s o f t h e s e s o i l s i n d i c a t e d t h a t t h e y were l o w e r i n s i l i c a , alumina and i r o n o x i d e s t h a n more mature pedogenic s o i l s and c o n s i d e r a b l y h i g h e r i n l i m e (as a r e s u l t o f i n c l u d e d , p a r t i a l l y weathered l i m e s t o n e f r a g m e n t s ) . A n a l y s i s 3, T a b l e 1 i s t y p i c a l o f t h i s s t a g e o f development.

The s o i l s o f t h e

N o r t h e a s t e r n Coastal P l a i n were s i m i l a r t o t h o s e i n N o r t h w e s t e r n Yucatan, except

62 t h a t t h e y were somewhat deeper, c o n t a i n e d f e w e r l i m e s t o n e fragments and were composed o f b e t t e r c r y s t a l l i z e d k a o l i n i t e ( d i f f r a c t o g r a m 5, F i g , 2 ) .

Analyses

4 and 5 on T a b l e 1 show t h a t t h e i r more advanced s t a g e o f development i s a l s o r e f l e c t e d i n h i g h e r s i l i c a , alumina, and i r o n c o n t e n t s and l o w e r c a l c i u m l e v e l s . Quinones (1975) r e p o r t e d c a t i o n exchange c a p a c i t i e s f o r t h e s e s o i l s a t a p p r o x i m a t e l y 30 meq/100 g and d e s c r i b e d them as " O r t h i c R h o d u s t a l f s " ( V e r t i c L u v i sols).

These s o i l s have developed i n a r e g i o n o f h i g h e r r a i n f a l l , g r e a t e r

t o p o g r a p h i c r e l i e f and where d i a g e n e t i c processes have a c t e d t o t r a n s f o r m t h e c l a y s t o more p e r f e c t l y c r y s t a l l i n e k a o l i n i t e and t o e l i m i n a t e l e s s s t a b l e cons t i t u e n t s ( t a l c , boehmite and c h l o r i t e ) .

I n t h e C e n t r a l H i l l D i s t r i c t , where

r e l i e f i s g r e a t e s t and r a i n f a l l somewhat h i g h e r , a c c u m u l a t i o n o f pedogenic c l a y s f r e q u e n t l y exceeds 20 meters and t h e most advanced s t a t e o f s o i l m a t u r i t y f o r t h e r e g i o n i s found.

X-ray a n a l y s e s ( d i f f r a c t o g r a m 1, F i g . 3 ) r e v e a l e d

t h a t t h e o n l y c r y s t a l l i n e phase p r e s e n t i s k a o l i n i t e and, i n a l l cases, t h i s m i n e r a l i s p r e s e n t as t h e w e l l c r y s t a l l i z e d f o r m t h a t c h a r a c t e r i z e s pedogenic l i m e s t o n e s o i l s i n an advanced s t a g e o f development. OriginBecause o f t h e l a c k o f c l a s t i c m a t e r i a l s i n t e r b e d d e d w i t h t h e Yucatan l i m e stones, t h e pedogenic c l a y s o f t h e n o r t h e r n p e n i n s u l a can o n l y owe t h e i r o r i g i n t o t h e a c c u m u l a t i o n and a l t e r a t i o n o f t r a c e q u a n t i t i e s o f i m p u r i t i e s t h a t were

w

n

'

h

"

'

F i g . 2. X-ray d i f f r a c t o g r a m s o f r e s i d u a l s o i l s f r o m N o r t h w e s t e r n Coastal P l a i n ( a n a l y s e s 1 t h r o u g h 4) and N o r t h e a s t e r n Coastal P l a i n ( a n a l y s i s 5 ) . O r i e n t e d s l i d e s , copper K-alpha r a d i a t i o n .

63 TABLE 1 Chemical analyses o f Yucatan d e t r i t a l , pedogenic and d i r e c t c r y s t a l l i z a t i o n c l a y s . A l s o shown a r e p a l y g o r s k i t e and s e p i o l i t e analyses from o t h e r l o c a t i o n s . O e t r i t a l Clays

Res idua 1

Palygorskite-Sepiolite

OXIDE

1

2

3

4

5

6

7

8

9

Si02

45.09

47.28

20.70

30.39

40.40

45.20

62.60

60.00

61;OO

A1203

14.91

14.50

12.80

34.21

27.80

28.80

9.40

9.50

9.80

3.80

FeO +

3.68

13.10

4.40

8.92

6.70

6.20

2.50

3.70

2.70

2.3C

Fe203 CaO

7.09

3.15

21.50

1.42

2.00

0.56

0.13

0.24

0.60

0.37

MgO Na20

2.18 0.40

0.90

1.00

0.79

0.60

0.35

11.00

10.60

11.20

17.30

2.50

0.06

nr

0.05

0.05

0.03

0.02

0.03

0.34

KZO T i O2

1.26

nr

0.29

0.30

0.48

0.52

0.71

0.14

0.80

nr

0.53

1.28

1.20

1.30

0.38

0.40

0.20

0.05

42.50

21.11

20.00

18.50

20.50

20.60

20.50

22.60

L.O.I.

24.11

18.49

Mixed Layer OXIDE Si02 2'3 FeO +

Non-Yucatan P a l y g o r s k i t e - S e p i o l i t e

11

12

13

14

15

16

17

53.5

45.0

59.53

G1.60

59.09

53.98

53.03

28.0

26.3

11.58

6.82

6.84

0.20

3.34

4.28

4.34

3.47

0.87

4.21

0.01

1.67

Fe203 CaO

0.92

0.54

2.31

0.67

0.01

0.04

0.89

MgO Na20

1.2

1.8

9.63

14.22

14.12

22.80

23.43

0.15

0.50

0.35

nr

nr

0.58

1.44

0.63

0.45

0.25

nr

nr

0.16

nr

0.34

0.49

nr

nr

1.66

14.16

14.18

K20 Ti02 L.O.I.

0.43 21.0

10 64.00

21.5

nr

nr 20.00

16.15

fl (1971)

( a ) K a o l i n i t e - M o n t m o r i l o n i t e ( m o d i f i e d a f t e r Schultz, ( b ) Attapulgus, Georgia (Robertson, 1961) ( c ) P a l y g o r s k i t e , South A f r i c a (Heystek and Schmidt, 1953) ( d ) P a l y g o r s k i t e , A u s t r a l i a (Rogers,

3 aJ,

1954)

( e ) S e p i o l i t e , Nevada (Post, 1978) ( f ) S e p i o l i t e , U.S.S.R. present i n t h e p a r e n t limestones.

(Teodorovitch, 1961) X-ray d i f f r a c t i o n and i n s o l u b l e r e s i d u e

analyses have shown t h a t t h e o n l y p o s s i b l e source m a t e r i a l s were t h e m i n e r a l s talc,

c h l o r i t e , and t r a c e amounts o f s m e c t i t e and mixed-layer c l a y s .

Some

v o l c a n i c ash may a l s o have been p r e s e n t as i s ( i n d i r e c t l y ) i n d i c a t e d by t h e abundant i r o n oxides present i n these s o i l s (Quinones, 1975).

The o r i g i n s o f

t h e m i n e r a l s t a l c and c h l o r i t e a r e more f u l l y discussed i n t h e s e c t i o n d e a l i n g

64 w i t h " p r i m a r y " ( d i r e c t c r y s t a l 1 i z a t i o n ) c l a y s b u t , based on abundance5 i n t h e i n s o l u b l e r e s i d u e s , i t seems l i k e l y t h a t c h l o r i t e and p o s s i b l e s m e c t i t e c l a y s have served as t h e source m a t e r i a l f o r t h e b u l k o f t h e pedogenic c l a y s now found on t h e p e n i n s u l a .

The development o f k a o l i n i t e would p o s s i b l y a r i s e as a

consequence o f a r e a c t i o n s i m i l a r t o t h a t d e s c r i b e d by B e r n e r (1971): (smectite)

(Kaol i n i t e )

( 1 ) 4NaA1MgSi4010(OH)2 + 6H2C03%=3A14Si4010(OH)4

+ 2Mgf2 + 2Na' +6HC03- +

1OH4S iO4 The r e a c t i o n shows t h a t t h e f o r m a t i o n o f k a o l i n i t e i s f a v o r e d where t h e HC03-/ H2C03 r a t i o i s low, whereas t h e r e a c t i o n proceeds t o t h e l e f t where t h e r a t i o i s high.

The f o r m e r would be t h e expected r e s u l t i n an a r e a o f r e c e n t l y u p l i f t e d

l i m e s t o n e s undergoing chemical w e a t h e r i n g b y t h e a c t i o r l o f m e t e o r i c ( i .e., Yucatan P e n i n s u l a ) .

the

The a c t u a l f o r m a t i o n o f k a o l i n i t e f r o m e i t h e r c h l o r i t e o r

smectite parent c l a y s i s thus c o n t r o l l e d b y reactions i n v o l v i n g carbonic a c i d which, i n l i m e s t o n e t e r r a n e s , a r e e s s e n t i a l l y " s e l f b u f f e r i n g " ( s e e G a r r e l s and Dreyer, 1952).

The c o n t r o l o f pH a c t s t o moderate t h e r a t e a t w h i c h breakdown

o f t h e l i m e s t o n e and a c c u m u l a t i o n o f t h e pedogenic s o i l m a t e r i a l o c c u r s and may f u r t h e r a c t t o r e t a r d t h e a c c u m u l a t i o n o f alumina d u r i n g t h e d i s s o l u t i o n of p r i mary a l u m i n o - s i l i c a t e s ( c h l o r i t e and s m e c t i t e ) .

Under such c o n d i t i o n s , any

alumina l i b e r a t e d w i l l l i k e l y r e a c t w i t h d i s s o l v e d s i l i c a t o i n i t i a l l y form

30

20

10

F i g . 3. X-ray d i f f r a c t o g r a m s o f r e s i d u a l s o i l s f r o m C e n t r a l H i l l D i s t r i c t ( a n a l y s i s 1 ) and E a s t e r n B l o c k F a u l t D i s t r i c t ( 2 and 3 ) . O r i e n t e d s l i d e s , copp e r K-alpha r a d i a t i o n .

65 amorphous o r p o o r l y c r y s t a l l i n e k a o l i n i t e by t h e r e a c t i o n proposed b y B e r n e r (1971):

(Kaol i n i t e )

+

( 2 ) 2A1 (OH) 3amorp,

2H4Si0 5 A1 S i 0 (OH) 4aq. lo 4amorp.

For r e a c t i o n ( 2 ) t o proceed t o t h e r i g h t , maintenance o f s u f f i c i e n t c o n c e n t r a t i o n s of s i l i c a a r e r e q u i r e d , o t h e r w i s e t h e f o r m a t i o n o f k a o l i n i t e i s i n h i b i t e d and Al(OH),

persists.

I n t h e N o r t h w e s t e r n and, t o a l e s s e r e x t e n t , t h e N o r t h -

e a s t e r n Coastal P l a i n o f Yucatan where r e l i e f i s l o w and t h e r a i n f a l l l e s s t h a n one m e t e r per: y e a r , s i l i c a has been p a r t i a l l y removed and t h e r e a c t i o n has t a k e n place sluggishly w i t h the r e s u l t t h a t the s o i l s contain a mixture o f poorly c r y s t a l l i z e d k a o l i n i t e and boehmite.

I n areas o f t h i c k e r s o i l s and i n h i b i t e d

drainage, s i l i c a a c t i v i t i e s a r e m a i n t a i n e d a t h i g h e r l e v e l s t h a t i n s u r e t h a t r e a c t i o n ( 2 ) w i l l proceed t o t h e r i g h t .

Hence t h e s o i l s o f t h e C e n t r a l H i l l

D i s t r i c t l a c k boehmite and c o n s i s t , a l m o s t w h o l l y , o f w e l l c r y s t a l l i z e d k a o l i n i t e ( s e e I s p h o r d i n g , 1974). DETRITAL CLAYS Clays i n t h i s c a t e g o r y a r e l a r g e l y r e s t r i c t e d t o t h e E a s t e r n B l o c k F a u l t D i s t r i c t ( F i g . 1 ) and t o s c a t t e r e d " p o l j e - l i k e " b a s i n s t h a t l i e s o u t h o f t h e S i e r r a de T i c u l and e a s t o f Campeche.

E x c e l l e n t exposures o f t h e s e c l a y s may

a l s o be seen i n t h e S t a t e o f Q u i n t a n a Roo a l o n g t h e Escarcega-Chetumal highway. Abundant sand and s i l t - s i z e d q u a r t z , as w e l l as t h e b l a c k opaque m i n e r a l s m a g n e t i t e and i l m e n i t e , c l e a r l y r e f l e c t a d e t r i t a l o r i g i n f o r t h e s e sediments. I n c o n t r a s t t o t h e f r i a b l e t o s l i g h t l y p l a s t i c , r e d o r reddish-brown c o l o r of t h e p r e v i o u s l y d e s c r i b e d pedogenic c l a y s , t h e s e c l a y s a r e h i g h l y p l a s t i c and a r e c h a r a c t e r i s t i c a l l y g r a y , d a r k brown o r b l a c k i n c o l o r .

The l a c k o f an i d e n -

t i f i a b l e C - h o r i z o n would cause many o f t h e s e c l a y s t o b e d e s c r i b e d as "rendzinas" ("Rendolls",

u s i n g t h e 1960 Comprehensive System t e r m i n o l o g y ) .

Mineral-

o g i c a l l y , t h e s e s o i l s were dominated by s m e c t i t e , b u t a l s o c o n t a i n e d l e s s e r amounts o f k a o l i n i t e ( s e e d i f f r a c t o g r a m s 2 and 3, F i g . 3 ) .

Chemically, t h e s e

were l o w e r i n alumina and i r o n o x i d e s and h i g h e r i n a l k a l i s , l i m e , and magnesia when compared w i t h t h e pedogenic c l a y s .

T y p i c a l a n a l y s e s a r e presented i n

Table 1 ( a n a l y s e s 1 and 2 ) . Origin The o b v i o u s c l a s t i c components t h a t make up t h e s e c l a y s s t r o n g l y suggests t h a t t h e y were d e r i v e d f r o m a i r - b o r n e and sea-borne d e t r i t u s t h a t was c a r r i e d n o r t h w a r d f r o m v o l c a n i c s o u r c e l a n d s t o t h e s o u t h i n B e l i z e and C e n t r a l Guatemala.

D e p o s i t i o n l a r g e l y t o o k p l a c e i n l a k e s and i n f r i n g i n g lagoons p r i o r t o

u p l i f t o f t h e n o r t h e r n p e n i n s u l a d u r i n g t h e l a t e Neogene.

U p l i f t o f t h e east-

e r n s i d e o f t h e p e n i n s u l a and c o n c u r r e n t down-to-the-basin

faulting

trapped

66 marine w a t e r s i n b l o c k f a u l t b a s i n s , f o r m i n g s a l i n e l a k e s .

Climatic conditions

o v e r t h e p e n i n s u l a were p r o b a b l y s i m i l a r t o t h o s e c h a r a c t e r i z i n g t h e a r e a a t p r e s e n t i n t h a t a r a i n y season o f r e l a t i v e l y s h o r t d u r a t i o n ( 3 t o 4 months) was f o l l o w e d by a l o n g d r y season.

Such c o n d i t i o n s a c t e d t o p r e v e n t t h e r a p i d

transformation o f t h e smectite c l a y s t o k a o l i n i t e (formation o f t h e smectite c l a y s , themselves, i s t h o u g h t t o have l a r g e l y t a k e n p l a c e i n t h e s o u r c e l a n d s by a l t e r a t i o n o f v o l c a n i c a s h ) .

I n areas o f t h e p e n i n s u l a where r a i n f a l l was

g r e a t e r , t h e poor d r a i n a g e a s s o c i a t e d w i t h t h e s e c l a y s c r e a t e d seasonal swamps o r savannas, p e r m i t t i n g t h e c l a y s t o remain s a t u r a t e d f o r l o n g e r p e r i o d s o f time.

Such c o n d i t i o n s s i m i l a r l y r e s t r i c t t h e removal o f c a t i o n s and l e a d t o

t h e meta-stable persistence o f smectite.

No such s m e c t i t e c l a y s a r e p r e s e n t

i n t h e modern l a k e s o f t h e p e n i n s u l a (Lake B a c a l a r , Lake Chichankanab, e t c . ) r e f l e c t i n g t h e absence o f a s u i t a b l e source m a t e r i a l ( i . e . ,

volcanic ash).

These l a k e s a r e composed o f b o t t o m sediments dominated b y c a r b o n a t e s and m i n o r 9Y PS um * PRIMARY CLAYS (DIRECT CRYSTALLIZATION) W i t h o u t q u e s t i o n , t h e most unusual m i n e r a l s f o u n d on t h e Yucatan P e n i n s u l a a r e v a r i o u s forms o f magnesium s i l i c a t e s and a l u m i n o - s i l i c a t e s t h a t a r e b e s t i n t e r p r e t e d as h a v i n g Yormed by processes i n v o l v i n g d i r e c t c r y s t a l l i z a t i o n . S p e c i f i c a l l y , these include:

c h l o r i t e , t a l c , p a l y g o r s k i t e , s e p i o l i t e and mont-

morillonite. T a l c and C h l o r i t e Bodine (1972) i d e n t i f i e d t a l c and c h l o r i t e as a u t h i g e n i c p r o d u c t s i n marine, h y p e r s a l i n e sediments i n t h e e a s t e r n Caribbean.

T h e i r presence was a t t r i b u t e d

t o t h e h y p e r h a l m y r o l i c response o f t e r r i g e n e o u s sediments t o t h e h i g h magnesium a c t i v i t i e s o f hypersaline waters.

I n Yucatan, n e i t h e r t a l c n o r c h l o r i t e has

been i d e n t i f i e d i n macroscopic f o r m b u t b o t h a r e commonly d e t e c t e d i n X-ray a n a l y s e s o f b o t h t h e c a r b o n a t e r o c k s and t h e pedogenic s o i l s o f t h e n o r t h e r n p e n i n s u l a ( e s p e c i a l l y i n t h e N o r t h w e s t e r n Coastal P l a i n D i s t r i c t ) .

Their close

a s s o c i a t i o n w i t h d o l o m i t i c r o c k s s t r o n g l y suggests t h a t t h e y have formed b y d i r e c t c r y s t a l l i z a t i o n as a consequence o f t h e d i a g e n e t i c a l t e r a t i o n o f t h e d o l o mite.

S u p p o r t f o r t h i s i s seen i n t h e X-ray d i f f r a c t o g r a m s w h i c h possess s t r o n g

f i r s t and t h i r d o r d e r r e f l e c t i o n s , i n d i c a t i n g t h a t t h e c h l o r i t e i s an i r o n - p o o r (magnesium-rich) v a r i e t y .

Two p o s s i b l e r e a c t i o n s a r e suggested b y t h e w r i t e r

t o e x p l a i n t h e presence o f t a l c : (1)

4H4Si04 + H20 + 3 C a M g ( C 0 3 ) 2 ~ M g 3 S i , 0 1 0 ( O H ) 2

A

FR = -13.35

+ 3CaC03 + 3C02

67 (2)

3Mg+2 + H20

+

6HC03-l

+

4H4Si04S=izMg3Si4010(OH)2 + 3H20 + 6H2C03

A F = ~-25.8 Reaction ( 1 ) forms t a l c by t h e a c t i o n o f s i l i c a - b e a r i n g groundwaters on d o l o mite; r e a c t i o n ( 2 ) d e r i v e s t h e m i n e r a l b y d i r e c t c r y s t a l l i z a t i o n f r o m groundwater s o l u t i o n s .

Because no t h i n s e c t i o n e v i d e n c e has been observed showing

d o l o m i t e a l t e r i n g t o t a l c , i t i s l i k e l y t h a t t h e m i n e r a l has formed by a r e action s i m i l a r t o (2).

The d i a g e n e t i c i n v e r s i o n o f h i g h naonesium c a l c i t e t o

low magnesium c a l c i t e would s u p p l y t h e needed magnesium which, i n t u r n , would r e a c t w i t h s i l i c a and c a r b o n i c a c i d i n t h e p o r e waters t o f o r m t a l c .

The f o r -

mation o f t h e magnesium c h l o r i t e s c o u l d i n v o l v e a s i m i l a r process and d i f f e r o n l y i n t h e r e q u i r e d a c t i v i t i e s o f magnesium, s i l i c a and alumina.

The j o i n t

occurrence o f t h e two m i n e r a l s i n d i a g e n e t i c a l l y a l t e r e d d o l o m i t e s t h r o u g h o u t the northern peninsula a l s o supports t h i s conclusion.

The p e r s i s t e n c e of b o t h

m i n e r a l s i n t h e y o u t h f u l pedogenic s o i l s o f t h e N o r t h w e s t e r n Coastal P l a i n can probably be a t t r i b u t e d t o t h e l o w r a i n f a l l e x p e r i e n c e d by t h i s p a r t of t h e peninsula.

To t h e south, and e a s t , where r a i n f a l l l e v e l s a r e g r e a t e r , b o t h

m i n e r a l s a r e absent as s o i l c o n s t i t u t e n t s . Palygorskite-Sepiolite C l a y s Occurrence.

Unlike the "attapulgite" (palygorskite) deposits o f the

G e o r g i a - F l o r i d a r e g i o n o f t h e U n i t e d S t a t e s , t h e p a l y g o r s k i t e and p a l y g o r s k i t e s e p i o l i t e c l a y s o f Yucatan o c c u r as i s o l a t e d , r e l a t i v e l y t h i n l e n s e s t h a t a r e r a r e l y t r a c e a b l e f o r more t h a n a few t e n s o f meters, l a t e r a l l y ( s e e l o c a t i o n map, F i g . 4 ) .

Further, i n c o n t r a s t t o t h e deposits i n eastern United States,

those i n Yucatan a r e n o t f o u n d i n t e r b e d d e d w i t h p h o s p h a t i c sediments and smect i t e c l a y s b u t r a t h e r o c c u r as c o n f o r m a b l e l e n s e s o r " p l u g l i k e " d e p o s i t s w i t h i n dolomites.

I n appearance, t h e s e c l a y s a r e w h i t e t o t a n i n c o l o r , range f r o m a

few m i l l i m e t e r s t o o v e r one m e t e r i n t h i c k n e s s and do n o t c o n t a i n any macroscopic d e t r i t a l components.

Schultz,

g fi (1971)

have r e p o r t e d t h e presence

o f rounded g r a i n s o f q u a r t z i n t h e f i n e s i l t f r a c t i o n o f s p a t i a l l y r e l a t e d clays, thus i t i s possible t h a t f u t u r e d i l i g e n t searching might a l s o reveal similar material i n t h e palygorskite clays. History.

Van Olphen (1966) f i r s t n o t e d t h a t c e r t a i n c l a y s i n Yucatan

were used as components i n an unusual pigment known a s "Maya B l u e " t h a t was manufactured by t h e pre-Columbian I n d i a n s o f t h e r e g i o n .

A r n o l d (1967, 1971)

l a t e r i d e n t i f i e d t h e m i n e r a l as " a t t a p u l g i t e " and f u r t h e r commented on i t s i m portance as an i n g r e d i e n t i n pre-Columbian ( a n d p r e s e n t day) ceramicware.

The

m i n e r a l was t h u s known t o t h e Maya I n d i a n s hundreds o f y e a r s b e f o r e t h e coming o f t h e f i r s t Europeans and was termed Sac l u ' u m (Maya f o r " w h i t e e a r t h " ) by t h e indigenous p o t t e r s .

Because of i t s l i m i t e d w a t e r a b s o r b i n g p r o p e r t i e s i t was

68 mixed w i t h o t h e r c l a y s t o add s t r e n g t h t o ceramicware; when mixed w i t h i n d i g o , i t produced a d i s t i n c t i v e , h i g h l y p r i z e d , o r g a n i c pigment (Maya B l u e ) which was

w i d e l y disseminated t h r o u g h o u t t h e r e g i o n as a t r a d e w a r e i t e m .

One v i l l a g e i n

t h e a o r t h e r n p e n i n s u l a , Sacalum ( a Spanish c o r r u p t i o n o f Sac l u ' u m ) , has appar e n t l y served as a major source o f t h i s c l a y f o r o v e r 800 y e a r s !

Here t h e c l a y

occurs as a l e n s a p p r o x i m a t e l y one meter t h i c k and i s l o c a t e d a t t h e b o t t o m of a large

c e n o t e some 15 meters below t h e ground s u r f a c e .

Access t o t h e d e p o s i t

i s p r o v i d e d b y means o f s t a i r s c a r v e d i n t o t h e s i d e o f t h e c e n o t e and an e x c e l l e n t d e s c r i p t i o n o f t h e s i t e may be f o u n d i n t h e d i s c u s s i o n by Bohor ( 1 9 7 5 ) .

It

i s i n t e r e s t i n g t o n o t e t h a t a l t h o u g h p a l y g o r s k i t e was a v a l u a b l e t r a d e i t e m , p r i z e d by a n c i e n t Maya p o t t e r s , t h e y d i d n o t , i n f a c t , c o n s i d e r i t as a t r u e "clay".

The Maya word f o r c l a y i s

k'at and,

a l t h o u g h t h e p a l y g o r s k i t e does be-

come s o f t and p l i a b l e when wet, i t a p p a r e n t l y possessed o t h e r p h y s i c a l p r o p e r t i e s t h a t p e r m i t t e d i t s d i s t i n c t i o n f r o m o t h e r c l a y s t h a t were r o u t i n e l y used f o r ceramic purposes ( A r n o l d , 1 9 6 7 ) .

F i g . 4. G e o l o g i c map o f t h e Yucatan P e n i n s u l a showing l o c a t i o n o f p a l y g o r s k i t e and s e p i o l it e c l a y s .

69

M i n e r a l o g y and Chemistry.

X-ray d i f f r a c t i o n a n a l y s e s c a r r i e d o u t on

c l a y s c o l l e c t e d a t Sacalum c o n f i r m e d A r n o l d ' s c o r r e c t i d e n t i f i c a t i o n o f t h e m i n e r a l as p a l y g o r s k i t e ( s e e I s p h o r d i n g , 1973).

Though n o t r e p o r t e d by Arnold,

t h e m i n e r a l s e p i o l i t e was a l s o p r e s e n t i n one sample c o l l e c t e d near t h e base o f the lens.

T h i s m i n e r a l , w h i l e u s u a l l y encountered o n l y i n t r a c e amounts, d i d

c o n s t i t u t e t h e dominant m i n e r a l i n s e v e r a l samples c o l l e c t e d n e a r t h e Maya r u i n s o f Etzna.

Where p a l y g o r s k i t e was t h e c h i e f m i n e r a l , t h e c l a y s were s o f t ,

p l a s t i c when wet, and l a c k e d any appearance o f bedding; where s e p i o l i t e was dominant, t h e : c l a y s were t o t a l l y n o n p l a s t i c and c o n s i s t e d o f p a p e r - t h i n l a y e r s . Chemical a n a l y s e s o f t h e Yucatan p a l y g o r s k i t e - s e p i o l i t e c l a y s a r e p r e s e n t e d i n Table 1.

Analyses 7, 8, and 9 a r e t y p i c a l o f t h e p a l y g o r s k i t e - r i c h c l a y s

whereas 10 i s f r o m t h e s e p i o l i t e l e n s n e a r Etzna.

When compared w i t h analyses

f r o m elsewhere i n t h e w o r l d , t h e Yucatan p a l y g o r s k i t e c l a y s a r e seen t o be s i m i l a r , c h e m i c a l l y , whereas t h e Yucatecan s e p i o l i t e ( w h i c h c o n t a i n e d some p a l y g o r s k i t e ) was r i c h e r i n s i l i c a and alumina and l o w e r i n magnesia.

D e t a i l e d de-

s c r i p t i o n s and l i t h o l o g i c s e c t i o n s o f s e v e r a l o f t h e p a l y g o r s k i t e l o c a l i t i e s i n n o r t h e r n Yucatan may be f o u n d i n Bohor ( 1 9 7 5 ) . Origin.

E x c l u d i n g t h e p r e v i o u s l y d i s c u s s e d pedogenic and d e t r i t a l

c l a y s , a l l o t h e r s on t h e p e n i n s u l a a r e l i k e l y t o have formed b y d i r e c t c r y s t a l l i z a t i o n e i t h e r from marine waters o r during diagenesis o f dolomites.

T h i s con-

c l u s i o n has been s u p p o r t e d b y a number o f p r i o r i n v e s t i g a t i o n s , most o f which were d i r e c t e d toward t h e genesis o f t h e p a l y g o r s k i t e c l a y s ( s e e I s p h o r d i n g , 1973; Bohor, 1375; DePablo, 1976).

One c o n t r o v e r s y s t i l l e x i s t s , however, and

i n v o l v e s a mixed l a y e r kaolinite-montmorillonite t h a t was i d e n t i f i e d by S c h u l t z , _ et _ a1 (1971) f r o m t h r e e l o c a t i o n s i n t h e n o r t h e r n p e n i n s u l a .

These c l a y s were

d e s c r i b e d as o c c u r r i n g i n l e n s e s 1 t o 2 m e t e r s t h i c k w i t h i n e n c l o s i n g l i m e stones, c o n t a i n e d l i t t l e q u a r t z and were o f h i g h p u r i t y ( a n a l y s e s 11 and 12, Table l ) , and were a t t r i b u t e d an o r i g i n by t h e w e a t h e r i n g o f v o l c a n i c ash. Though S c h u l t z , _ et_ a1 _(1971) concede t h a t such an o r i g i n i s " h i g h l y s p e c u l a t i v e ; t h e y l i s t s e v e r a l l i n e s o f e v i d e n c e t h a t , t h e y b e l i e v e , s u p p o r t such an o r i g i n . If t h e s e mixed l a y e r c l a y s are, i n f a c t , d e r i v e d by a l t e r a t i o n o f v o l c a n i c ash,

i t would have an i m p o r t a n t b e a r i n g on t h e o r i g i n o f t h e p a l y g o r s k i t e - s e p i o l i t e c l a y s because:

( 1 ) a t l e a s t i n one case p a l y g o r s k i t e c l a y s a r e f o u n d i n c l o s e

p r o x i m i t y t o one o f . t h e m i x e d - l a y e r s i t e s and ( 2 ) i t has been argued t h a t some p a l y g o r s k i t e s elsewhere i n t h e w o r l d have formed by a l t e r a t i o n o f p y r o c l a s t i c m a t e r i a l s ( s e e G r i m , 1933; G r e m i l l i o n , 1965). One s t r o n g argument a g a i n s t a v o l c a n i c o r i g i n f o r t h e m i x e d - l a y e r c l a y s (and t h e p a l y g o r s k i t e - s e p i o l i t e c l a y s ) i s t h e l a c k o f any s i g n i f i c a n t amount o f ash i n t h e rocks o f t h e northern peninsula.

A s e a r c h f o r t h i s m a t e r i a l has been

c a r r i e d on f o r y e a r s , p r i n c i p a l l y by a r c h a e o l o g i s t s i n t e r e s t e d i n e s t a b l i s h i n g

70 t h e o r i g i n o f " v o l c a n i c ash" temper t h a t has been i d e n t i f i e d i n p o t t e r y f r a g ments from some s i t e s i n t h e r e g i o n . that

...."The

B r a i n e r d (1958) a d m i t t e d , however, ( p . 70)

sources o f v o l c a n i c ash temper i n Yucatan have n o t been l o c a t e d "

and . . . . I ' t h e q u a n t i t i e s o f t h i s m a t e r i a l which must have been used . . . . . p r e c l u d e t h e p o s s i b i l i t y of i m p o r t a t i o n o f v o l c a n i c ash f r o m t h e n e a r e s t a r e a s where volcanism now occurs, a d i s t a n c e o f some 509 k i l o m e t e r s . "

F u r t h e r , Shepard

(1952), i n a d i s c u s s i o n o f l o c a l Yucatecan p o t t e r y , n o t e d ( p . 264-265).

..."The

ash i n a l l these s e c t i o n s i s comparable i n f o r m and i n sparseness and f i n e n e s s of mineral i n c l u s i o n s

.....As

t y p e o f ash i n Yucatan."

o f y e t we:have no c l u e t o t h e o c c u r r e n c e o f t h i s

As n o t e d i n an e a r l i e r paper ( I s p h o r d i n g and W i l s o n ,

1974), because t h e presence o f any s i g n i f i c a n t q u a n t i t i e s o f ash i s d o u b t f u l , either:

( 1 ) t h e m a t e r i a l i d e n t i f i e d by v a r i o u s a r c h a e o l o g i s t s as ash i f i n d i -

genous i s , i n f a c t , some o t h e r m a t e r i a l ( t h e f i n e g r a i n e d p a l y g o r s k i t e s o r t h e m i x e d - l a y e r c l a y s a r e l i k e l y c a n d i d a t e s ) o r ( 2 ) t h e p o t t e r y i s non-indigenous tradeware. F u r t h e r arguments a g a i n s t a v o l c a n i c o r i g i n can be r a i s e d by examining e v i dence used b y S c h u l t z , eJaJ

(1971) and t h e n c o n s i d e r i n g p o s s i b l e a l t e r n a t i v e s .

F o r example, t h e y proposed t h a t a v o l c a n i c ash f a l l d u r i n g t h e Eocene ( p . 139)

...."seems

t h e most l i k e l y p r e c u r s o r o f t h e c l a y beds because ( 1 ) v o l c a n i c ash

o r m o n t m o r i l l o n i t e derived from i t i s the parent m a t e r i a l o f t h e mixed-layer

kaolinite-montmorillonite i n F l o r i d a and Japan, ( 2 ) many v o l c a n i c ashes and b e n t o n i t e 5 d e r i v e d t h e r e f r o m a r e v e r y l o w i n q u a r t z , as a r e t h e Yucatecan c l a y s , ( 3 ) much v o l c a n i c d e b r i s o c c u r s i n t h e T e r t i a r y r o c k s o f t h e G u l f o f Mexico r e g i o n , and ( 4 ) because an ash f a l l i s one o f t h e few r e a s o n a b l e mechanisms f o r i n t r o d u c i n g n e a r l y p u r e a l u m i n o - s i l i c a t e m a t e r i a l i n t o a s e d i m e n t a r y sequence dominated b y carbonate r o c k s .

I'

Regarding p o i n t (l), t h e w r i t e r knows o f no m i x e d - l a y e r c l a y s i n F l o r i d a w i t h a proven v o l c a n i c o r i g i n .

On t h e c o n t r a r y , most e v i d e n c e t o d a t e has

argued a g a i n s t any m a r i n e o r a i r b o r n e t r a n s p o r t o f v o l c a n i c ash f r o m sources i n western U n i t e d S t a t e s o n t o t h e F l o r i d a P l a t f o r m .

Strong supporting evidence

f o r t h i s i s f o u n d i n t h e s t r i k i n g l y d i f f e r e n t m i n e r a l s u i t e s found i n e a s t e r n , c e n t r a l and western G u l f Coast Miocene sediments (see I s p h o r d i n g , 1971, 1973). I t would be d i f f i c u l t , a t b e s t , t o e x p l a i n how w e s t e r n - d e r i v e d v o l c a n i c d e b r i s

c o u l d be d e p o s i t e d on t h e F l o r i d a P l a t f o r m and subsequently "weather" t o p a l y g o r s k i t e , s e p i o l i t e and m i x e d - l a y e r c l a y s , w h i l e b e i n g c o m p l e t e l y a b s e n t i n contemporaneous sediments i n e a s t e r n M i s s i s s i p p i , Alabama and w e s t e r n F l o r i d a . S i m i l a r l y , p o i n t (2),

t h e l o w q u a r t z c o n t e n t o f Yucatecan c l a y s , c o u l d a l s o

be e x p l a i n e d b y t h e f o r m a t i o n o f t h e s e m i n e r a l s i n an area c h a r a c t e r i z e d by n e g l i g i b l e c l a s t i c sedimentation.

Such i s f r e q u e n t l y t h e case where m i n e r a l s

a r e formed by d i r e c t c r y s t a l l i z a t i o n on a submerged c a r b o n a t e s h e l f environment.

71 As a case i n p o i n t , t h e b o t t o m sediments o f t h e p r e s e n t submerged p o r t i o n o f t h e Yucatan P l a t f o r m c o n t a i n n e g l i g i b l e amounts o f q u a r t z because t h e y l i e a g r e a t d i s t a n c e f r o m any source o f such m a t e r i a l .

F u r t h e r t o t h e south, as t h e d e l t a

o f t h e Usumacinta R i v e r i s approached, q u a r t z becomes i n c r e a s i n g l y more common and c a r b o n a t e sediments l a r g e l y d i s a p p e a r . The abundance o f v o l c a n i c ash i n G u l f Coast T e r t i a r y sediments ( p o i n t 3 ) i s n o t argued by t h e w r i t e r .

Numerous s t u d i e s have c l e a r l y i d e n t i f i e d v o l c a n i c

sources f o r s p e c i f i c G u l f Coast f o r m a t i o n s ( s e e McBride, Lindemann and Freeman, 1968).

The w r i t e r would, however, argue t h e e x i s t e n c e o f any such m a t e r i a l e a s t

o f t h e S t a t e o f M i s s i s s i p p i f o r reasons a l r e a d y s t a t e d .

F u r t h e r , assuming t h a t

p a s t wind d i r e c t i o n s were n o t g r e a t l y d i f f e r e n t from t h o s e o f t h e p r e s e n t , t h e p r i n c i p a l sources f o r such p y r o c l a s t i c d e b r i s on t h e Yucatan P l a t f o r m would l i e hundreds o f m i l e s t o t h e e a s t , i n Jamaica, H i s p a n i o l a and t h e A n t i l l e s .

I n the

e v e n t t h a t such t r a n s p o r t d i d t a k e place, t h e n o t h e r s u p p o r t i n g e v i d e n c e should a l s o be p r e s e n t .

T h i s would i n c l u d e g l a s s shards, m i c r o l i t e s o r c r y s t a l l i t e s ,

as w e l l as s i l t - s i z e d , pyroxene o r z i r c o n .

euhedral o r subhedral g r a i n s o f amphibole, p l a g i o c l a s e , These m a t e r i a l s a r e a b u n d a n t l y p r e s e n t i n o l d e r T e r t i a r y

f o r m a t i o n s i n t h e w e s t e r n G u l f Coast o f t h e U n i t e d S t a t e s t h a t a r e known t o have been, i n p a r t , d e r i v e d f r o m v o l c a n i c sources (see Swineford, F r y e and Leonard, 1955; McBride, Lindemann and Freeman, 1968). R e f e r r i n g t o p o i n t ( 4 ) , and ash f a l l i s

not

t h e o n l y " r e a s o n a b l e mechanism"

f o r i n t r o d u c i n g p u r e a l u m i n o - s i l i c a t e m a t e r i a l i n t o a sedimentary b a s i n domin a t e d by c a r b o n a t e r o c k s .

Jeans (1971) n o t e d t h a t each y e a r an e s t i m a t e d 475

m i l l i o n t o n s o f alumina and s i l i c a a r e c a r r i e d i n s o l u t i o n and d e p o s i t e d i n t r a n s i t i o n a l m a r i n e environments.

Areas a d j a c e n t t o t e r r a c e s

undergoing t r o p i -

c a l w e a t h e r i n g r e c e i v e a d i s p r o p o r t i o n a t e s h a r e o f t h i s t o t a l because o f t h e r i g o r o u s w e a t h e r i n g regimen t h a t c h a r a c t e r i z e s such r e g i o n s .

The a l k a l i n e pH

o f t h e m a r g i n a l m a r i n e w a t e r s t h e n i n s u r e s t h a t a s i z e a b l e p r o p o r t i o n of t h e i o n s w i l l be p r e c i p i t a t e d i n t h e f o r m o f alumina and s i l i c a h y d r o x i d e g e l s and colloids.

Such c o n d i t i o n s c o u l d , t h u s , e x p l a i n t h e h i g h p u r i t y o f t h e "source

m a t e r i a l s " o f t h e m i x e d - l a y e r (and p a l y g o r s k i t e - s e p i o l i t e ) c l a y s of Yucatan and would a v o i d problems i n e x p l a i n i n g t h e l a c k o f any s i g n i f i c a n t q u a n t i t i e s o r known d e p o s i t s o f remnant ash on t h e p e n i n s u l a .

Even where ash has been t h o u g h t

t o be o f importance.as an u l t i m a t e s o u r c e m a t e r i a l (such as t h e d e t r i t a l c l a y s

o f t h e E a s t e r n B l o c k F a u l t D i s t r i c t ) , t h e m a t e r i a l d e p o s i t e d i s b e l i e v e d t o have a l r e a d y been t r a n s f o r m e d t o s m e c t i t e c l a y p r i o r t o i t s d e p o s i t i o n (and c o n t a i n s abundant q u a r t z and heavy m i n e r a l s as " i m p u r i t i e s " ) . Conclusions.

Based on t h e p r e c e e d i n g evidence, t h e w r i t e r b e l i e v e s

t h a t t h e p a l y g o r s k i t e - s e p i o l i t e c l a y s of Yucatan and t h e p a r e n t m a t e r i a l f o r t h e m i x e d - l a y e r c l a y s formed by d i r e c t c r y s t a l l i z a t i o n i n m a r g i n a l b a s i n s and lagoons, a d j a c e n t t o a l i m e s t o n e t e r r a c e t h a t was s l o w l y emerging from t h e sea.

72 D i r e c t c r y s t a l l i z a t i o n as a mechanism f o r t h e f o r m a t i o n o f such c l a y s i s n o t without precedent.

M c C l e l l a n (1964) argued a g a i n s t a v o l c a n i c o r i g i n f o r t h e

F l o r i d a - G e o r g i a " F u l l e r s E a r t h " d e p o s i t s as d i d a l s o Post (1978) f o r f o u r s e p i o l i t e d e p o s i t s near Las Vegas, Nevada.

S i m i l a r l y , M i l l o t (1970) c a l l e d

upon d i r e c t c r y s t a l l i z a t i o n t o e x p l a i n a seaward s u c c e s s i o n o f m o n t m o r i l l o n i t e , p a l y g o r s k i t e and s e p i o l i t e t h a t o c c u r s i n T e r t i a r y b a s i n s i n West A f r i c a . M i l l o t n o t e d t h a t as l o n g as s u f f i c i e n t a l u m i n a was p r e s e n t , m o n t m o r i l l o n i t e was t h e s t a b l e phase t o c r y s t a l l i z e .

F u r t h e r seaward i n t h e b a s i n , where

alumina a c t i v i t i e s were lower, m o n t m o r i l l o n i t e was r e p l a c e d b y p a l y g o r s k i t e and, f i n a l l y , s e p i o l i t e where alumina was absent.

The e x p l a n a t i o n o f f e r e d by M i l l o t ,

i n which t h e f o r m a t i o n o f t h e t h r e e m i n e r a l s i s a f u n c t i o n o f magnesium, s i l i c a , and a l u m i n a a c t i v i t i e s , i s e s p e c i a l l y a t t r a c t i v e f o r t h e Yucatan c l a y s because i t e l i m i n a t e s t h e problem o f e x p l a i n i n g why m i x e d - l a y e r c l a y s formed by weatheri n g o f ash a t one s i t e w h i l e a s h o r t d i s t a n c e away n e a r l y p u r e p a l y g o r s k i t e was f o r m i n g i n contemporaneous sediments b y w e a t h e r i n g o f t h e same " a s h " .

Bohor

(1975) has e l e g a n t l y e x p l a i n e d t h e c l o s e s i m i l a r i t y between Yucatecan and F l o r i d a p a l y g o r s k i t e c l a y s by u t i l i z i n g a model t h a t p o s t u l a t e s t h a t Yucatan and F l o r i d a were once i n c l o s e p r o x i m i t y d u r i n g t h e Mesozoic.

A s t h e two a r e a s

s l o w l y began t o move away f r o m each o t h e r , as a consequence o f p l a t e movement, s i m i l a r t y p e s o f sediments were f o r m i n g i n t h e two a r e a s i n b a c k - r e e f , environments.

lagoonal

The m i x e d - l a y e r k a o l i n i t e - m o n t m o r i l l o n i t e c l a y s may have o r i g i -

n a l l y p r e c i p a t e d as m o n t m o r i l l o n i t e s ( i n response t o l o c a l l y h i g h e r a l u m i n a c o n c e n t r a t i o n s ) whereas t h e p a l y g o r s k i t e c l a y s (and s e p i o l i t e s ) r e p r e s e n t e d l o w e r a c t i v i t i e s of alumina.

The t r a n s f o r m a t i o n o f m o n t m o r i l l o n i t e t o t h e

m i x e d - l a y e r s t r u c t u r e may have o c c u r r e d a t a l a t e r t i m e ( d i a g e n e t i c a l l y ) by t h e a c t i o n o f a c i d groundwaters,

by t h e mechanism suggested f o r s i m i l a r c l a y s

i n F l o r i d a b y G r e m i l l i o n (1965). REFERENCES

Arnold, D., 1967. Sak Lu'um i n Maya c u l t u r e : and i t s p o s s i b l e r e l a t i o n t o Maya B l u d . U n p u b l i s h G d - P m T h e s i s , Dept. o f Anthropology, U n i v . o f I l l i n o i s , 53 p. A r n o l d , D., 1971. Ethnomineralogy o f T i c u l Yucatan p o t t e r s . Am. A n t i q u i t y , 36: 20-40. Berner, R., 1971. P r i n c i p l e s o f Chemical S e d i m e n t a t i o n . McGraw-Hill, New York, 191 p. Bodine, M., 1972. Layer s i l i c a t e s i n t h e modern m a r i n e h y p e r s a l i n e environment. Abs., 2 1 s t Clay M i n e r a l s Conf., 9 t h Ann. Mtg., Clay M i n e r a l s SOC., p. 19. Bohor, 8. F., 1975. A t t a p u l g i t e i n Yucatan. In: Guidebook FT-4, 1975 I n t . C l a y Conf., I n s t . Geol., Univ. Nat. de Mexico, L. DePablo, Ed., p. 95-125. B r a i n e r d , G., 1958. The a r c h a e o l o g i c a l ceramics o f Yucatan. U n i v . o f Cal i f o r n i a , A n t h r o p o l o g i c a l Records: 36, 374 p. DePablo, L., 1976. A t a p u l g i t a s e d i m e n t a r i a m a r i n a de Yucatan, Mexico. I n s t . de Geologia, B o l e t i n 96, Univ. Nac. Autonoma de Mexico, 3-30. G a r r e l s , R. and R. Dreyer, 1952. Mechanism o f l i m e s t o n e r e p l a c e m e n t a t l o w temp e r a t u r e s and p r e s s u r e s . B u l l . Geol. SOC. Amer., 63:325-380.

73 Heystek, H. and E. Schmidt, 1953. The m i n e r a l o g y o f t h e a t t a p u l g i t e - m o n t m o r i l l o n i t e d e p o s i t s i n t h e Springbok F l a t s , T r a n s v a a l . Trans. Geol. SOC. Amer., 56: 99-115. I s p h o r d i n g , W . C., 1971. Provenance and p e t r o g r a p h y o f G u l f Coast Miocene s e d i ments. I n : G e o l o g i c a l Review o f N o r t h F l o r i d a M i n e r a l Resources. Southe a s t e r n Geol. Zoc. 1 5 t h F i e l d Conf., 43-54. I s p h o r d i n g , W. C., 1973. D i s c u s s i o n o f t h e o c c u r r e n c e and o r i g i n o f sedimentary p a l y g o r s k i t e - s e p i o l i t e d e p o s i t s . Clays Clay M i n e r . , 21: 391-401. I s p h o r d i n g , W. and E. Wilson, 1974. The r e l a t i o n s h i p of " v o l c a n i c ash", Sak Lu'um and p a l y g o r s k i t e i n n o r t h e r n Yucatan Maya ceramics. Am. A n t i q u i t y , m83-488. Jean, C., 1971. The n e o f o r m a t i o n o f c l a y m i n e r a l s i n b r a c k i s h and m a r i n e e n v i ronments. : C l a y s Clay Miner., 9: 209-217. McBride, E., W. Lindemann and P. Freeman, 1968. L i t h o l o g y and P e t r o l o g y o f t h e Guedan ( C a t a h o u l a ) F o r m a t i o n i n South Texas. Bur. Econ. Geol. I n v e s t . 63, 122 p. M c C l e l l a n , G., 1964. P e t r o l o g y o f A t t a p u l g u s Clay i n N o r t h F l o r i d a and Southwest Georgia. Unpublished Ph.D. Thesis, Dept. o f Geology, U n i v . o f I l l i n o i s , 127 p. M i l l o t , G., 1970. Geology o f Clays. S p r i n g e r - V e r l a g , New York, 429 p. Post, J . , 1978. S e p i o l i t e d e p o s i t s o f t h e Las Vegas, Nevada area. Clays C l a y Miner., 26: 58-64. Quinones, H., 1975. S o i l s t u d y area 4. I n t r a z o n a l s o i l s o f n o r t h e r n Yucatan P e n i n s u l a . I n : Guidebook FT-4, 1975 I n t . Clay Conf., I n s t . Geol., U n i v . Nat. de Mexico, L. DePablo, Ed., 70-93. Robertson, R., 1961. The o r i g i n o f E n g l i s h F u l l e r s E a r t h s . Min. Mag., 4: 282'287. P a l y g o r s k i t e f r o m Queensland. Rogers, L., A. M a r t i n and K. N o r r i s h 1954. Min. Mag., 30: 534-540. S c h u l t z , L., A. Shepard, P. Blackmon and H. Starkey, 1971. M i x e d - l a y e r k a o l i n i t e - m o n t m o r i l l o n i t e f r o m t h e Yucatan Peninsula, Mexico. Clays Clay Miner., 19: 137-150. Shepard, A., 1952. Ceramic t e c h n o l o g y . Carnegie I n s t i t u t i o n o f Washington Yearbook 51, 263-266. Swineford, A., J. F r y e and A. Leonard, 1955. P e t r o g r a p h y o f t h e l a t e T e r t i a r y v o l c a n i c ash f a l l s i n t h e c e n t r a l G r e a t P l a i n s . Sed. P e t r o l . , 54: 829-838. A u t h i g e n i c M i n e r a l s i n Sedimentary Rocks ( T r a n s l a t i o n ) . T e o d o r o v i t c h , G. 1961. C o n s u l t a n t s Bureau, New York, 120 p. Van Olphen, H., 1966. Maya Blue: c l a y - o r g a n i c pigment. Science., 154: 645467.

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75

PALYGORSKITE IN THE TERTIARY DEPOSITS OF THE ARMORICAN MASSIF *

J.

ESTEOULE-CHOUX

Laboratoire de Gdologie G. 4 , UniversitP de RENNES I, Campus de Beaulieu, Avenue du General Leclerc 35042 RENNES C6dex - FRANCE ABSTRACT I n the Armorican Massif, palygorskite has been found in Eocene and Oligo-

cene deposits, in marine, transitional marine and lacustrine depositional environments.

The palygorskite occurs in layers containing either exclusively

clays or carbonates (dolomite, or calcite).

The palygorskite is sometimes

alone, sometimes closely associated with a ferriferous illite, and most rarely with smectite. When palygorskite is associated with iron rich illites, the genesis of these two minerals can be considered as a manifestation of the antagonism A1-Mg, and this paragenesis is regulated by the iron content of the depositional environment. When palygorskite is associated with smectite, transitional textures were never identified by electron microscopy.

This suggests that

palygorskite has formed by precipitation from solution. I n all the cases, palygorskite is formed by direct precipitation in lagoons and in shallow marine waters of elevated salinity: the chemical character

cf the sedimentation is determined by water depth, a climate favourable to an intense evaporation and the absence of tectonic activity, prohibiting the arrival of coarse terrigenous material.

The source of the necessary ions was the

deep lateritic weathering of the different rocks of the Armorican Massif. INTRODUCTION Palygorskite has been identified in many Tertiary deposits of the Armorican Massif (Estgoule-Choux, 1 9 6 7 ) . and at Stampian (Fig. 1 ) .

It appears at Upper Lutetian, at Bartonian

At Upper Lutetian and at Bartonian, palygorskite

occurs in the clayey beds and also in the marly beds which complete the filling of the Campbon basin.

This basin seems to have behaved itself like a residual

shallow gulf: in this continually subsiding gulf the sea has deposited thirty meters of sediments without any detrital particles. basin became continental. in.

During the Bartonian the

In the Oligocene deposits, palygorskite appears aga-

It is a constituent of the clayey beds interbedded in the limestones of

the Upper serie of the Stampian of Saffrg. Palygorskite is also present in the "Calcaires a Archiacines" where it is associated with a smectite, and in the clays of the Stampian of Langon, St. SBglin and Loutehel. * Presented at the International Clay Conference 1981

I n these three ba-

76

Fig. 1.

Localisation and age of the palygorskite deposits of the Armorican Massif.

77

sins, palygorskite is closely associated with iron-rich illite (this illite contains between 10 and 15pb of Fe 0 ) . This paragenesis of palygorskite-ferri2 3 ferous illite is present in all the samples but the proportions of each of these two minerals vary. These basins mark out the traces of an old marine g u l f oriented SouthEast, North-West, exZending from the Basse Loire to the Bay of St. Brieuc.

In

this gulf, the subsidences were localized but important and they allowed the deposition of sediments many maters thick: 331 m for instance at SaffrE (Borne, 1978) where the age of the bottom layers is Upper Lutetian.

These Eocene and Oligocene palygorskites are either marine or continental, but always littoral: fresh water swamps of the Bartonian of Campbon (OllivierPierre, 1980).

In the lacustrine Sannoisian of Landean, palygorskite is pre-

sent in minor amounts together with a great quantity of smectite. The discovery of a new deposit (The Bohu-Robien) shows that palygorskite may also be associated in the Armorican Massif with small amounts of smectites. THE BOHU-ROBIEN DEPOSIT This deposit is located 8 km to the North of the Oligocene basin of Quessoy, the extension of which was suspected long ago (Est6oule-Choux, 1967).

The age

of this new deposit cannot be specified because the sediments are azoic.

But

compared to other Tertiary basins and particularly to the basin of Quessoy, one may suppose that parts of the sediments of the Bohu-Robien belong. to the Stampian. Palygorskite has been found only in one bore-hole, which has given the sequence outlined in Table 1 . Table 1 - Mineralogical composition of the bore-hole of Le Bohu-Robien; in capital letters, the dominant minerals, in italic, the minerals in very small amounts. 1,50 m

ochreous clay

2,OO m

ochreous and greenish clay

SMECTITE, k a o l i n i t e , micaceous clay SMECTITE, k a o l i n i t e , t r a c e s of micaceous

clay 2,70 m

ochreous clay

SMECTITE, KAOLINITE, t r a c e s of micaceous

clay 3,20 m

green clay

SMECTITE, k a o t i n i t e , t r a c e s of micaceous

clay 3,50 m

friable grey clayey limestone (72% of C03-Ca)

4,OO m

ochreous clay

SMECTITE, palygorskite

5.20 m

grey and ochreous clay

SMECTITE, t r a c e s ,of k a o l i n i t e

SMECTITE

=

PALYGORSKITE

,

6.60 m

light grey clay

SMECTITE, trmces of k a o l i n i t e

7.60 m

light grey clay

MICACEOUS CLAY, k a o l i n i t e , smectite

8.60 m

grey and white clay

KAOLINITE, micaceous c l a y , smectite

9.60 m

grey and pink clay

KAOLINITE, micaceous c l a y

78

Compared to what can be seen in the basin of Quessoy, it is possible to associate the two bqttom layers where kaolinite is dominant with the detritic sedimentation of the Upper Eocene now recognized in the Armorican Massif. Above, the sediments with smectite, and smectite with palygorskite may be regarded as belonging to the Stampian. GENESIS OF THE PALYGORSKITE AND OF THE ASSOCIATED CLAY MINERALS Palygorskite is closely associated with either an iron-rich illite, or a smectite: it is not possible to discuss the genesis of the first without considering the two others. The problem of the origin of the smectites of the Paleogene of the Armorican Massif has already been studied (Est&ule-Choux,

1967).

These smectites

cannot be detrital because during the Cretaceous and the beginning of the Tertiary the continents were kaolinised (EstGoule-Choux, 1967, Louail, 1981). Hydromorphous tropical soils on the other hand, were never identified.

Even

if such soils had developed, some traces must have remained in low lying grounds that are preserved from erosion.

An origin from volcanic ashes

is also ex-

cluded. Moreover, the absence of coarse detrital material (sands, silts) is an additional support for a chemical sedimentation which developed while the continents were lateritised. The green iron-rich illites of the Stampian have been regarded as formed by direct precipitation; they cannot have formed from smectites because there are not smectites

on

the nearby continent and in the basins with illite smec-

tites were never identified: the illite i s either pure or associated with palygorskite in greater or lesser amounts. When illite is dominant, the carbonates are ankeritic; when palygorskite is dominant, carbonates are calcite and/or dolomite.

The constant paragenesis palygorskite-iron-rich illite seems to be

directed by the iron content of the sedimentary environment, which controls the formation of illite. When iron is absent, aluminium and magnesium remain and palygorskite forms by direct precipitation with no ferriferous carbonates. The genesis of palygorskite and of illite could be considered a s a manifestation of the antagonism A1-Mg;

It can be concluded from this, that paly-

gorskite was neoformed whether in its pure form (basin of Campbon, upper part of Saffr6 and in certain beds of the basin of Langon and the basin of S t . Seglin) or associated with iron-rich illite (Estgodle-Choux, 1967).

Once neoformation

was nearly the only mode of possible genesis envisaged for palygorskite and sepiolite deposits.

However, palygorskite was found in soils (Vanden Heuvel,

1966; Millot, et al., 1969; Lamouroux, 1971) and it has been considered

as

detrital in origin in the sediments of the North-East of the Persian gulf (Estioule, et al., 1970).

More recently, its formation by diagenetic alteration

of smectite has been suggested sy some authors, especially Decarreau et al.,

79

PLATE I C a p t i o n on p . 8 2 .

80

PLATE I1

81

PLATE I I1 Caption on next page.

82

PLATE I P a l y g o r s k i t e o f l e Bohu-Robien ( S t a m p i a n ) a s s o c i a t e d w i t h s m e c t i t e 1 and 3 : S.E.M.

o f t h e l i m e s t o n e a t 3.50 m s h o w i n g t h e d e l i c a t e meshworks o f

palygorskite coating carbonate grains.

2 and 4 : T.E.M.

o f d i s p e r s e d c l a y samples s e p a r a t e d f r o m t h e a c i d - i n s o l u b l e

r e s i d u e o f t h e same l i m e s t o n e .

5 and 6 : S.E.M.

and T.E.M.

o f t h e o c h r e o u s c l a y a t 4 m.

The l i t t l e p a r t i c l e s w i t h b l u r r e d o u t l i n e s v i s i b l e o n t h e f i g . 6 a r e smectite. PLATE I 1

1 and 2 : S.E.M.

and T.E.M.

o f t h e s m e c t i t e ( g r e e n c l a y e y bed a t 3 , 2 0 m) w h i c h

l i e s on t h e p a l y g o r s k i t e r i c h 1imestone. 3 and 4 : S.E.M.

and T.E.M.

o f t h e s m e c t i t e ( g r e y and o c h r e o u s c l a y a t 5 . 2 0 m)

under t h e p a l y g o r s k i t e c l a y e y bed. 5 and 6 : T.E.M.

o f t h e t w o c l a y e y beds o f S a n n o i s i a n o f Landean where s m e c t i t e

i s a s s o c i a t e d t o some l a t h s o f p a l y g o r s k i t e .

PLATE I 1 1 P a l y g o r s k i t e a s s o c i a t e d w i t h i r o n - r i c h i l l i t e (S.E.M.

and T.E.M.)

1 and 2 : P a l y g o r s k i t e o f Campbon ( B a r t o n i a n ) : r e m a r k some p a r t i c l e s o f f e r r i f e r o u s i11 it e .

3 and 4 : P a l y g o r s k i t e o f L o u t e h e l ( S t a m p i a n ) a s s o c i a t e d t o some p a r t i c l e s o f ferriferous i l l i t e . 5 and 6 : P a l y g o r s k i t e and f e r r i f e r o u s i l l i t e i n e q u a l q u a n t i t i e s i n a bed o f t h e S t a m p i a n o f Langon.

83 (1975) or by Trauth (1977).

This last hypothesis cannot be considered for the

palygorskite of Le Bohu-Robien.

Indeed, when one studies the two beds of this

deposit in the transmission electron microscope, one cannot identify transitional phases between smectites and palygorskite

Smectites look like isometric

particles with blurred contours and palygorskite shows aggregates of laths (Pl. I, fig. 2,4,6).

Never could laths of palygorskite growing from the par-

ticles of smectites such as those described by Trauth ( 1 9 7 7 ) be observed. On the other hand, in the calcareous bed the scanning electron microscope shows palygorskite fibres coating carbonate or aggregates of carbonate grains. Fig. 3 (Pl. I) is similar to the figure published by Hassouba and Shaw (1980): for these two authors "the delicate meshworks of palygorskite in these marl sediments strongly suggest an authigenic rather than a detrital origin for the palygorskite, as it is difficult to envisage how such delicate fabrics could have been preserved during transport and deposition"

(p. 8 0 ) .

Moreover, there

is no transition between the two palygorskite rich beds, the lower ochreous smectite rich bed and the upper green smectite rich bed.

In micrographs 1,2,3

and 4 (Pl. 11) not one lath of palygorskite can be observed and the smectite shows the same form as when it is associated with palygorskite. Galan et al., (1975) who observed similar features think that "the absence of a transition

between the two excludes the possible alteration in place of montmorillonite to palygorskite in the magnesium-rich environment" ( p . 93). Figs. 5 and 6 (Pl. 11) show some laths of palygorskite associated with the smectites of the Sannoisian of Landean.

On plate 111, palygorskite asso-

ciated with some ferriferous illite can be seen. ENVIRONMENT, PALEOGEOGRAPHY The characteristics of the deposits, as well as the data obtained from laboratory studies, particularly electron microscope observations, permit us to propose for the palygorskite associated with smectites the same authigenic origin as that which had been given for other Breton palygorskite deposits: the problem of the genesis of these minerals must be considered on a large scale. All the Tertiary basins are located in areas which were subsident as far back as the Eocene and which are limited by N-NW, S-SE faults (fault of Quessoy Nort-sur-Erdre, fault of Pont-Rean and little grabens of Landean and of Laval-Thevalles) (fig. I).

Moreover, they are situated in a lateritic land-

scape: lateritised antecambrian shales (Langon, St-S6glin for instance), kaolinised granite and schists (Quessoy, Le Bohu-Robien).

The sediments are

characterized by the absence of associated detrital constituents even at Quessoy, Le Bohu-Robien, where the granite and the schists are very rich in coarse quartz.

The absence of tectonic activity during Palaeogene favoured

84

the action of wet and warm tropical climates,s~p?ortinglateritic weathering which supplied the basins with elements necessary to form calcite, dolomite, palygorskite, ferrifereous illites, smectites and sometimes gypsum.

It must

be noted that the smectites-palygorskite deposits are less numerous than those composed of iron rich illites and/or palygorskite: sepiolite has never been identified

.

This occurence of palygorskite in marine, non-marine or sometimes brackish deposits, going from Upper Lutetian to Stampian (with a period of uniquely kaolinitic sedimentation at the end of the Upper Eocene) in always subsident basins results from the combination of several ideal conditions for direct precipitation: the source of the necessary ions was the Armorican Platform undergoing rigorous tropical weathering and the concentration of the solutions in low-lying areas communicating with the open sea intermittently, and resembling salt marshes, was favoured by the climate becoming relatively drier. CONCLUSION While palygroskite may form by a variety of processes

-

direct precipi-

tation, alteration of volcanic ashes, detrital, transformation of smectites

-

the palygorskite of the Tertiary deposits of the Armorican Massif is the result of direct precipitation in shallow, marginal seas or lakes adjacent to areas undergoing tropical weathering.

Such an origin had been proposed by

Isphording (1973) for the Georgia-Florida deposits in southeastern United States. REFERENCES Borne, V., 1978. Etude d'un sondage profond dans le bassin tertiaire de Saffrg ( 4 4 ) . (Si?dimentologie, biostratigraphie, Paleoecologie). D.E.A. Univ. Nantes, 46 pp. Decarreau, A., Sautereau, J.P. and Steinberg, M. 1975. GSn'ese des mineraux argileux du Bartonien moyen du Bassin de Paris. Bull. SOC. fr. Mineral, Cristallogr., 98: 142-151. EstGoule-Choux, J., 1967. Contribution a l'itude des argiles du Massif Armoricain. Argiles des alterations et argiles des bassins ssdimentaires tertiaires. Thkse Sci., Rennes, 319 pp. Estgoule, J., Esteoule-Choux, J., Melquen, M. and Seibold, E., 1970. Sur la pr6sence d'attapulgite dans les se'diments recents du Nord-Est du Golfe Persique. C.R. Acad. Sc. Paris, 274: 1153-1156. Galan, E., Brell, J.M., La Iglesia, A. and Roberton, R.H.S., 1975. The Caceres palygorskite deposit, Spain. Proceedings of the Intern. Clay Conf. Mexico, July, 16-23, 1975: 81-94. Hassouba, H. and Shaw, H.F., 1980. The occurence of palygorskite in Quaternary sediments of the coastal plain of North-West Egypt. Clay Minerals, 15: 77-83.

Isphording Wayne, C., 1973. Discussion of the occurence and origin of sedimentary palygorskite-sepiolite deposits. Clays and Clay Minerals 21: 391-401. Lamouroux, M., 1971. Etude de sols formgs sur roches carbonatges. Pidoghese fersiallitique au Liban. Th6se Sc., Strasbourg et Mgm. O.R.S.T.O.M., 56 (1972), 245 pp.

85

Louail, J., 1981. L a transgression cretacee au Sud du Massif armoricain. CCnomanien de 1'Anjou et du Poitou, CretacZ supzrieur de Vendsee. Etude stratigraphique, skdimentologique et minsralogique. ThSse Sci. Rennes, 456 pp. Millot, G., Paquet, J. and Ruellan, A., 1 9 6 7 . Ngoformation de l'attapulgite dans les s o l s a carapaces calcaires de l a Basse-Moulouya (Maroc oriental). C.R. Acad. S c , , Paris, 2 6 8 : 2771-2774. Ollivier-Pierre, M.F., 1980. Etude palynologique (spores et pollens) de gisements paliogsnes du Massif Armoricain. Hem. SOC. Giol. Min. Bretagne, 25: 239 pp. Trauth, N., 1977. Argiles gvaportiques dans la sedimentation carbonatgee continentale et Gpicontinentale tertiaire. Bassin de Paris, Mormoiron et Salinelles (France), Ibel Ghassoul (Maroc). Sciences G6ologiques. Kem. 49: 695 pp. Vanden Heuvel, R.C., 1 9 6 7 . The occurence of sepiolite and attapulgitein the calcareous zone of a soil near Las Cruces, New Mexico, Clays and Clay Min., 13: 193-207.

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87

SEPIOLITE

-

PALYGORSKITE I N SPANISH TERTIARY BASINS: GENETICAL PATTERNS I N

CONTINENTAL ENVIRONMENTS* EMILIO GALAN ( * ) and ANTONIO CASTILLO (**)

(*) Dept. of Geology, F a c u l t y o f Chemistry, U n i v . o f S e v i l l a , Spain

(**) TOLSA, S . A . Nunez de Balboa 51, Madrid, Spain

ABSTRACT Spanish T e r t i a r y d e p o s i t s o f s e p i o l i t e and p a l y g o r s k i t e a r e formed i n l a c u s t r i n e o r p e r i m a r i n e environments. A c c o r d i n g t o t h e i r g e o l o g i c a l s e t t i n g and mineralogy t h e y can be grouped i n t o f o u r fundamental types, w i t h t h e f o l l o w i n g p r i n c i p a l f e a t u r e s : 1 ) T a j o b a s i n t y p e ; s e p i o l i t e formed i n d i s t a l zones o f a l l u v i a l - f a n s , o r i n p e r e n n i a l l a c u s t r i n e zones, by p r e c i p i t a t i o n f r o m a S i and M g - r i c h s o l u t i o n w i t h a pH between 8 and 9. Other a u t h i g e n i c m i n e r a l s formed i n t h i s environment were Mg-smectite, p a l y g o r s k i t e , carbonates and c h e r t . 2 ) T o r r e j o n t y p e ; p a l y g o r s k i t e formed i n t e c t o n i c b a s i n s on s l a t y basement from p a r t i a l l y d i s s o l v e d c h l o r i t e , and a l s o by d i r e c t p r e c i p i t a t i o n i n an a l k a l i n e environment. 3) Benfica-San M a r t i n de Pusa t y p e ; p a l y g o r s k i t e appears as t h e p r i n c i p a l c l a y m i n e r a l i n t h e cement o f conglomerates and sandstones, formed by d i a g e n e s i s i n t h e s e d e t r i t a l sediments, i n a s l i g h t l y a1 k a l i n e environment r i c h i n magnesium. 4) L e b r i j a t y p e ; p a l y g o r s k i t e - s e p i o l i t e m a r l s formed i n a p e r i m a r i n e b r a c k i s h l a c u s t r i n e environment r i c h i n S i and Mg. P a l y g o r s k i t e i s a l s o t h o u g h t t o be a t r a n s f o r m e d m i n e r a l f r o m i l l i t e . I n a l l these patterns t h e sedimentation o f authigenic c l a y minerals occurred under s e m i - a r i d o r seasonably a r i d c l i m a t i c c o n d i t i o n s d u r i n g p e r i o d s o f t e c t o n i c calm. INTRODUCTION S e p i o l i t e and p a l y g o r s k i t e a r e commonly found i n Spain, o c c a s i o n a l l y i n abundant amounts.

Some d e p o s i t s have g r e a t economic importance.

One o f these, i n V a l l e c a s , Madrid, was mined by means o f w e l l s and g a l l e r i e s during t h e l a t e 1600's.

The s e p i o l i t e was used i n t h e "manufacture of p i p e s

and c i g a r e t t e f i l t e r s " ( t h e s o f t e r v a r i e t y ) and as "a b u i l d i n g m a t e r i a l i n r u s t i c houses" ( V i l a n o v a , 1875).

Used p r i m a r i l y i n t h e manufacture of l i g h t

w a l l s d u r i n g t h e second h a l f o f t h e 1 9 t h c e n t u r y , i t was r e f e r r e d t o as "crazy r o c k " i n t h a t r e g i o n . lite.

Small l a b o r a t o r y ovens were a l s o made o f s e p i o -

V i l a n o v a (1875) i n t h a t paper d e s c r i b e d i n d e t a i l t h e s e p i o l i t e d e p o s i t s

i n Cabanas de l a Sagra and Yepes, Toledo. Between 1735 and 1808 t h e V a l l e c a s s e p i o l i t e was mixed w i t h c l a y f r o m Capodimonte, I t a l y , i n t h e ceramic p a s t e o f t h e famous p o r c e l a i n s o f t h e Buen R e t i r o i n M a d r i d (Prado, 1864).

In 1830 B e r t h i e r conducted t h e f i r s t known a n a l y s i s o f V a l l e -

*

Presented a t t h e I n t e r n a t i o n a l C l a y Conference 1981.

88 cas s e p i o l i t e . Mg0=23.8%;

ThE c o m p o s i t i o n was S i 0 2 = 5 3 . 8 % ;

A1203=1.2%;

H20=20%.

Spanish contributions t o the study o f these p h y l l o s i l i c a t e s have been v e r y i m p o r t a n t . mineralogists,

F o r more t h a n t h i r t y y e a r s ,

h a v e c o m p l e t e d n u m e r o u s s t u d i e s on t h e s t r u c t u r e , morphology,

physico-chemical

these minerals.

properties,

diffraction;

and Robertson (1971),

Huertas e t a l .

(19751, Galan (1979), La I g l e s i a (1977,

(1970,

on t h e r m a l a n a l y s i s ;

on e l e c t r o n m i c r o s c o p y a n d

1971 a n d 1 9 7 4 ) , G a l a n e t a l .

Fernandez A l v a r e z (1970,

on q e n e s i s ;

on s y n t h e s i s a t room t e m p e r a t u r e ;

M a r t i n V i v a l d i and L i n a r e s (1962),

and

Fenoll and M a r t i n V i v a l d i

1978), Serna (1973),

and Serna and Vanscoyoc (1978), physico-chemical

(1970),

and Galan and F e r r e r o (1982),

1978),

include:

on t h e m i n e r a l o g i c a l f o r m u l a o f

M a r t i n V i v a l d i and Ferioll

Martin Vivaldi

composition,

genesis and s y n t h e s i s o f

The m o s t r e l e v a n t S p a n i s h c o n t r i b u t i o n s

M a r t i n V i v a l d i a n d Cano ( 1 9 5 6 ) , sepiolite;

Spanish c l a y

e s p e c i a l l y M a r t i n V i v a l d i and h i s c o l l a b o r a t o r s ,

Serna e t a l .

(1968)

(1975),

on v a r i o u s s t r u c t u r a l a s p e c t s a n d

properties.

The c o m m e r c i a l i z a t i o v o f s e p i o l i t e i n S p a i n began i n 1945, a t which t i m e i n v e s t i g a t i o n s o f p o s s i b l e d e p o s i t s and t h e i r m i n e r a l o g i c a l c h a r a c t e r i s t i c s were c a r r i e d o u t (Lacazette, Vivaldi

a n d Cano,

1947; M a r t i n

1953).

S e p i o l i t e and p a l y g o r s k i t e a r e found as m i n o r components i n various types o f rocks.Reoorts

o f these minerals being found i n

Cambrian and S i l u r i a n s l a t e s a r e d o u b t f u l .

More f r e q u e n t and c r e d i -

b l e a r e r e p o r t s o f s e p i o l i t e i n Keuper c l a y s and m a r l s . Occurrences on p e r i d o t i t e s and b a s i c v o l c a n i c r o c k s ,

as w e l l as i n J u r a s s i c

dolomitic rocks are a l s o described (Alonso, Martin Vivaldi,

1972; O o r r o n s o r o ,

1970;

1978; G a l a n ,

C a b a l l e r o and

1979).

However,

the

greatest concentration o f these minerals occurred i n Spanish T e r t i ary basins under special environmental conditions. THE S P A N I S H TERTIARY BASINS The m o s t i m p o r t a n t T e r t i a r y b a s i n s a r e a l o n g t h e T a j o , and G u a d a l q u i v i r r i v e r s ( F i g .

Duero,

Ebro

1).

The b a s i n o f t h e T a j o c a n be d i v i d e d i n t o t h r e e s e c t i o n s o r sub-basins:

the eastern,

the central,

and t h e western.

The A l t o m i -

r a S i e r r a separates t h e e a s t e r n and t h e c e n t r a l , and t h e t h r e s h o l d o f Talavera de l a Reina, central

(Fig.

2).

Toledo,

separates t h e western from t h e

89

EXPLANATION A

ALMAZAN - - W I N

4E

A L W X T E BPSN

R

:ROUPAR

M

M.B

cra S

so 8 8

BdDpJoZ W N

8.C

WREM u)RRxxI(

CR

UUOIV) Rowu) WB-BASIN

C 1 6 . CALATAW-TERLU W I N

S.P0 T

V VA

z

F i g . 1.

-

T e r t i a r y basins i n the I b e r i a n Peninsula

Toward t h e south, and s e p a r a t e d b y t h e e a s t e r n spurs o f t h e Toledo Mountains, t h e T a j o b a s i n connects w i t h t h e Ciudad Real basin).

Toward t h e south-east,

-

D a i m i e l b a s i n ( t h e Manchegan

i t continues along t h e Albacete basin.

The Duero b a s i n has t h r e e d i f f e r e n t s e d i m e n t o l o g i c a l areas. The l a r g e s t , t h e V a l l a d o l i d sub-basin, o c c u p i e s t h e c e n t r a l zone. Toward t h e west, t h e Ciudad Rodrigo s u b - b a s i n i s f o u n d and toward t h e e a s t t h e Almazan ( F i g . 1 ) . The Duero b a s i n connects on t h e n o r t h - w e s t w i t h t h e Ebro b a s i n through t h e Bureba c o r r i d o r , The Ebro b a s i n c u t s a c r o s s t h e n o r t h - e a s t c o r n e r o f t h e I b e r i a n P e n i n s u l a i n a NW-SE d i r e c t i o n w h i c h s e p a r a t e s t h e I b e r i a n Range a t t h e s o u t h f r o m t h e Pyrenees a t t h e n o r t h , and t h e C a t a l a n Mountains a t t h e n o r t h - e a s t ( F i g . 1 ) . To t h e s o u t h o f t h e Ebro b a s i n and t o t h e e a s t o f t h e Almazan b a s i n l i e s t h e Calatayud-Teruel b a s i n , an i n t r a m o u n t a i n o u s b a s i n o f t h e I b e r i a n Range.

90

N

MI MADRID T: TOLEDO G = GUADALAJARA W i THE WESTERN SIB-BeSIN C :THE CENTRAL SUB-BASH(THE MALMilD BESIN1 E: THE EASTERN SUB-BbSW H = HUETE T : TABLADILCO P.M- PUEBLA DE MCUTALBAN S Y P i S I N W I N E€ PUSA T R = TALAVER4 DE L A REINA

F i g . 2.

-

0 a0 U l c____

The T a j o b a s i n

The T e r t i a r y b a s i n o f t h e G u a d a l q u i v i r i s l o c a t e d i t s e p a r a t e s t h e I b e r i a n M a s s i f f r o m t h e B e t i c Range

s m a l l T e r t i a r y b a s i n s : t h e Granada, t h e Guadix-Eaza,

n s o u t h e r n Spain; I n t h i s b a s i n appear

he Gorafe-Huelago,

etc.

I n G a l i c i a and A s t u r i a s , i n n o r t h w e s t e r n Spain, e x i s t s m a l l b a s i n s o f T e r t i a r y m a t e r i a l s d i r e c t l y l y i n g on t h e P a l e o z o i c basement. A s e r i e s o f s m a l l b a s i n s w i t h t h e same c h a r a c t e r i s t i c s : t h e T o r r e j o n , t h e Coria, t h e M o r a l e j a , and t h e Castelo-Branco can b e f o u n d i n t h e western p a r t o f t h e P e n i n s u l a (Spanish-Portugese b a s i n s ) .

A l s o i n t h e south, b u t w i t h

d i f f e r e n t s e d i m e n t o l o g i c a l c h a r a c t e r i s t i c s i s t h e Eadajoz b a s i n , wh ch c o i n c i d e s w i t h t h e h y d r o g r a p h i c b a s i n o f t h e Guadiana r i v e r . F i n a l l y , i n Levante ( e a s t e r n Spain) e x i ' s t s a g r e a t number o f sma 1 b a s i n s p a r t i a l l y interconnected, from Almeria t o Valencia. Most o f these b a s i n s were a f f e c t e d by c o n t i n e n t a l c o n d i t i o n s

91

a t l e a s t d u r i n g some stages o f t h e i r e v o l u t i o n .

The occurrence o f s e p i o l i t e -

p a l y g o r s k i t e m i n e r a l s i n Spain i s a s s o c i a t e d w i t h t h e s e c o n t i n e n t a l episodes, o r w i t h p e r i o d s o f a l i m i t e d c i r c u l a t i o n t o t h e sea.

THE TAJO BASIN Geological s e t t i n g The T a j o b a s i n i s l o c a t e d i n t h e c e n t r a l p a r t o f t h e P e n i n s u l a ( F i g . l ) , and i s bordered b y t h e Guadarrama and Gredos S i e r r a s on t h e n o r t h and n o r t h west, t h e Toledo Mountains on t h e south, and t h e I b e r i a n Range on t h e e a s t (Fig. 2 ) . T h i s b a s i n was formed b y f r a g m e n t a t i o n o f t h e s h i e l d ( t h e I b e r i a n N a s s i f ) d u r i n g t h e A l p i n e o r o g e n e s i s and was f i l l e d by a c o n t i n e n t a l s e d i m e n t a t i o n during the T e r t i a r y .

The basement o f t h e t r o u g h i s covered by Cretaceous

and Paleogene sediments, above which a r e found Neogene m a t e r i a l s a f f e c t e d o n l y by subsequent movements t h a t gave r i s e t o f o l d i n g ( A l i a and Capote, 1971). During t h e P l i o c e n e t i m e s t h e b a s i n t i l t e d t o w a r d t h e south-west. The c o n t i n e n t a l s e d i m e n t a t i o n o f t h i s b a s i n extends f r o m t h e Paleogene t o the Q u a t e r n a r y , t h e m a t e r i a l s d e r i v i n g f r o m t h e s u r r o u n d i n g mountains.

The

thickness o f t h e T e r t i a r y sediments r e a c h more t h a n 1600 meters (Carames e t a l . 1973) and p r o b a b l y as much as 3000 m e t e r s i n some areas (Megias e t a l . 1982). L i tho1 ogy The s e d i m e n t a t i o n o f t h e w e s t e r n s u b - b a s i n i s e s s e n t i a l l y d e t r i t a l ( g r a v e l s , sands and sandy c l a y s ) .

The c l a y s a r e m a i n l y composed of i l l i t e

and smecti t e s . The e a s t e r n sub-basin i s m a r l y - c a l c a r e o u s and g y p s i f e r o u s , w i t h d e t r i t a l intercalations.

I t s s e d i m e n t a t i o n has been c l e a r l y i n f l u e n c e d by t h e

I b e r i a n Range e s s e n t i a l l y composed o f Mesozoic l i m e s t o n e s , c l a y s and sands. The u p l i f t o f t h e A l t o m i r a S i e r r a o c c u r r e d a f t e r t h e e v a p o r i t i c s e d i m e n t a t i o n and d i d n o t s e r v e as a s o u r c e area f o r t h i s sub-basin. The c e n t r a l sub-basin i s t h e most i n t e r e s t i n g i n terms o f s e p i o l i t e and palygorskite.

A d e t r i t a l facies ( a l l u v i a l deposits) related t o the

surrounding mountains, b o r d e r s t h e c e n t r a l sub-basin, and i s known a c c o r d i n g t o i t s g e o g r a p h i c a l l o c a t i o n s , as t h e M a d r i d

92 facies,

Toledo facies,

(Benayas e t a l .

1960).

evaporitic facies (Fig.

A l c a r r i a f a c i e s and G u a d a l a j a r a f a c i e s It i n t e r f i n q e r s toward t h e c e n t e r w i t h an 3).

N

PEDlmNT _____

FUNTIAN LIMESTONES MARLY W0FKlES T W I T I O H FACIES DETRITAL SUEFACIES

a ____

DETRITAL F K I E S

[a$16 EVAFWfITIC

FAUES

-

SEPlOLlTE BED

Fig.

3.-

The C e n t r a l s u b - h a s i n o f t h e T a j o b a s i n S e c t i o n t y p e of

t h e T a j o b a s i n and g e n e r a l c r o s s s e c t i o n

NW-SE

11 = M a d r i d , T = = T o l e d o ,

G==Guadalajara

93

Between t h e M a d r i d f a c i e s and t h e e v a p o r i t i c f a c i e s i s a rnarlyclayey transition facies, cal characteristics.

l o c a l l y showing p l a y a - l a k e

t h e s e f a c i e s c a n be seen i n F i g .

of

sedimentologi-

The r e l a t i v e p o s i t i o n s and r e l a t i o n s h i p s o f The f o l l o w i n g i s a d e s c r i p t i o n

3.

their characteristics:

Detrital facies.

- C o n s i s t s o f conglomerates and f e l d s p a t i c sand

w i t h ssme i n t e r l a y e r i n g o f g r a v e l s a n d s a n d y c l a y s o f a r e d - y e l l o w ish color.

:

-

Transitions facies.

a) Detrital, subfacies: Located i n t h e lower p a r t , zone.

occupying p r i m a r i l y the eastern

I t i s made u p o f t w o b e d s .

The l o w e r i s c l a y e y ( d a r k

c l a y w i t h i l l i t e a n d l o w - c r y s t a l l i n e s m e c t i t e s ) w i t h some lens-shaped l e v e l s o f dolomitic

rocks.

A discontinuous

l a y e r o f s e p i o l i t e appears a t t h e t o p o f t h e l o w e r bed r e l a t e d t o t h e d o l o m i t i c l a y e r s . The t h i c k n e s s i s i r r e g u l a r (max.

2 m.).

The u p p e r b e d i s d e t r i t a l ,

c o n s i s t i n g of

fine

micaceous sands ( m o s t l y b i o t i t e s ) o f a d a r k green c o l o r . I n t h e upper middle p a r t there i s another l a y e r o f pinkish sepiolite,

o f wrinkled texture,

and t h i c k e r and more c o n t -

inuous than p r e v i o u s . A s s o c i a t e d w i t h c h e r t and c a l c i t e , i t continues t o the d e t r i t a l

facies (Madrid facies).

The

thickness o f t h i s l e v e l reaches 4 meters. b) Marly subfacies: T h i s s u b f a c i e s i s s m a l l e r i n s u r f i c i a l e x t e n s i o n and i s l o c a t e d t o t h e e a s t o f t h e p r e v i o u s l y d i s c u s s e d one.

It

c o n s i s t s o f l i m e s t o n e s , m a r l y limestones and s m e c t i t i c clays o f a saponitic nature. base a r e l a y e r s o f sand.

Toward t h e west and i n t h e

T h e t o p o f t h i s s u b f a c i e s i s made

up o f a brown l a y e r o f c h e r t and massive s e p i o l i t e ,

which

o c c a s i o n a l l y c o n t a i n p a l y g o r s k i t e as a m a j o r component. The l a y e r i s c o n t i n u o u s b u t o f v a r y i n g c o m p o s i t i o n . Fig.

4 i s a c o r r e l a t i o n diagram o f various sections

i n t h e Tajo basin.

Two l a y e r s o f s e p i o l i t e a r e c l e a r l y i n

5 s h o w s some X r a y d i f f r a c t i o n patterns corresponding t o c h a r a c t e r i s t i c

evidence i n t h e central sub-basin. materials o f t h i s facies.

Fig.

94 EXF'LANATITIW

SYECTITE-SEPIOLITE CLAY

c-l

YPlalTE ILLITE-SIECTITE

CLAY

LIMESTONE AND SEROClE-SIECTITE M A Y

0 OETRITAL FACIES E V I p w l T l C FACIE'

F i g . 4.

-

L i t h o s t r a t i g r a p h i c c o r r e l a t i o n diagram i n t h e T a j o b a s i n . S e c t i o n s o f : 1 ) T a l a v e r a d e l a Reina, 2 ) Maqueda, 3) V i c a l v a r o ,

'

4) Brihuega, 5) Y u n c l i l l o s - M a g d n , Chinchdn, 7 ) Pastrana, and 8) T a b l a d i l l o - P a r e j a areas

Evaporitic facies:

T h i s f a c i e s i s c h a r a c t e r i z e d by a l a r g e f o r m a t i o n o f

chemical sediments w h i c h can b e d i f f e r e n t i a t e d i n t o two s u b f a c i e s :

a ) a sub-

f a c i e s o f r e d g y p s i f e r o u s c l a y s , l i m e s t o n e s and sodium s a l t s ; and b ) a m a r l y calcareous subfacies which, toward t h e n o r t h - e a s t becomes t o t a l l y c a l c a r e o u s . I n b o t h l a y e r s , t h e r e a r e t r a c e s o f p a l y g o r s k i t e t o g e t h e r w i t h i l l i t e , and sometimes k a o l in i t e and smecti t e s

.

On t o p o f t h e s e m a t e r i a l s appears a bed made up o f m i c r i t i c c a l c a r e n i t e s and l i m e s t o n e d a t e d as P o n t i a n , which c r e a t e a r e g i o n a l l y t y p i c a l r e l i e f c a l l e d "mesas". A t t h e base of t h e l i m e s t o n e s '"mountain l e a t h e r " ( s e p i o l i t e ) has been found,

f o r example a t Jadraque i n G u a d a l a j a r a .

The youngest m a t e r i a l s a r e a P l i o - Q u a t e r n a r y bed o f r e d c l a y s and sandstones t h a t covers most of t h e T a j o sub-basin. On t h e b a s i s o f i n f o r m a t i o n f r o m s e i s m i c r e f l e c t i o n , c o n s i s t s o f f i v e t e c t o r e d i m e n t a r y u n i t s (TSU) (Megfas

t h e Madrid basin

95

m-a-sp 336

2.118

3b

Fig. 5.

-

L

L

Ib

ib

h

*

29

X-ray powder diffraction patterns of characteristic clay materials o f the Tajo basin. ( C u K radiation) 1.- I l l i t e - s m e c t i t e clay ( d e t r i t a l subfacies) , 2.- Vicalvaro s e p i o l i t e ( d e t r i t a l subfacies, lower l e v e l ) , 3 . - Low-crystalline Mg-smectite, 4.- Yunclillos s e p i o l i t e ( d e t r i t a l subfacies, lower l e v e l ) , 5.- Sepiolite (marly subfacies) , 6.- Palygorskite (marly subfacies). Sp = Sepiolite,

Pa = Palygorskite, Sin = Smectite, I = I l l i t e , Q = Quartz, F = Feldspars, Ca = Calcite, Do = Dolomite.

96 e t a l . 1982b).

According t o t h i s i n t e r p r e t a t i o n t h e p r e v i o u s l y described

l a y e r s o f s e p i o l i t e a r e l o c a t e d i n t h e f o l l o w i n g way: t h e upper l e v e l o f t h e d e t r i t a l s u b f a c i e s i n a r k o s i c t e c t o s e d i m e n t a r y u n i t (TSU 8 ) ; t h e l o w e r l e v e l o f t h e same s u b f a c i e s i n t h e upper p a r t o f TSU 6 ( u n i t made up o f d e t r i t a l and chemical subfacies, which, a t t h e edges, change t o f l u v i a l d e t r i t a l f a c i e s ) ; and f i n a l l y , t h e s e p i o l i t e l a y e r o r t h e m a r l y s u b f a c i e s i n t h e l o w e s t p a r t of TSU 7 ( d o l o m i t i z e d c a r b o n a t i c m a t e r i a l w i t h f i b r o u s c l a y minerals present). (Fig. 6).

9---

F i g . 6.

-

Tectosedimentary u n i t s i n t h e T a j o B a s i n a c c o r d i n g t o Megias e t a l . (1982b).

S e p i o l i t e l o c a t i o n a c c o r d i n g t o t h i s paper ( w i t h o u t s c a l e )

1.-Basement, 4.-Salts,

2.-Granite,

3a.-Mesozoic,

gypsum, magnesite, e t c .

3b.-Eocene-Oligocene,

(TSU 4 ) , 5 , - 6 . - D e t r i t a l

gypsum,

sand, d o l o m i t e , e t c . (TSU 5 and 6 ) , 7 . - D o l o m i t i z e d c a r b o n a t i c m a t e r i a l s w i t h f i b r o u s c l a y m i n e r a l s , and P o n t i a n l i m e s t o n e s (TSU 7 ) , 8 . - A r k o s i c u n i t (TSU 8 ) , 9.-Unconformity The c o r r e l a t i o n between t h e f a c i e s h e r e d e s c r i b e d and t h e i n v o l v e d TSU’s are indicated i n the adjoining table: TABLE I C o r r e l a t i o n between t h e f a c i e s d e s c r i b e d i n t h i s paper and t h e t e c t o s e d i m e n t a r y u n i t s (TSU) c i t e d by Megtas e t a1 (1982b) Pontian limestones

,

Detrital T r a n s i t i o n f a c i e s 1Mar,y Evaporitic facies

, .

Marly-Calcareous Gypsum

--

--

/

TSU 7b TSU 8 TSU 7a TSU 4,5,6

97 The V a l l e c a s - V i c a l v a r o s e p i o l i t e d e p o s i t ( p r o v i n c e o f M a d r i d ) T h i s d e p o s i t i s s i t u a t e d t o t h e n o r t h - e a s t o f t h e c i t y o f Madrid, and occupies a p p r o x i m a t e l y 6.6 Kin 2

.

I t i s a p a r t of t h e d e t r i t a l s u b f a c i e s i n t h e t r a n s i t i o n f a c i e s o f t h e T a j o b a s i n . F i g . 7 shows a l o g a t t h i s d e p o s i t .

C N R T AND SLICECUS LIMESTONE SYCTITE-SEPIOLITE

20m

CLAY

SEPIOLITE ILLITE-SMECTITE CLAY 25 m

&O&;IE

cyfySMECTITE-

W A Y LIMESTONE

F i g . 7.- Log a t V i c a l v a r o , M a d r i d Two e x p l o i t a b l e l a y e r s o f s e p i o l i t e a r e p r e s e n t .

The upper l a y e r changes

l a t e r a l l y t o dark c h e r t , and t h e l o w e r changes l a t e r a l l y t o s m e c t i t e s ( e s s e n t i a l l y o f t h e s t e v e n s i t e t y p e ) a t t h e n o r t h - w e s t (Galan e t a l . 1981). Toward t h e south-east,

t h e l o w e r s m e c t i t e c l a y s change t o s a p o n i t i c b e n t o n i t e s

o f i r r e g u l a r d i s t r i b u t i o n and q u a l i t y . The s e p i o l i t e i s f a i r l y p u r e (between 65% and more than 95%), b e i n g accompanied by q u a r t z , i l l i t e , f e l d s p a r s and carbonates. The l o w e r l e v e l c o n t a i n s s t e v e n s i t e , o r o t h e r p o o r l y - c r y s t a l l i z e d s m e c t i t e s ( F i g . 5, samples I n T a b l e I1 a r e chemical a n a l y s e s o f t h e s e s e p i o l i t e s . F i g . 8 i s an e l e c t r o n m i c r o g r a p h o f t h e s e p i o l i t e . O t h e r d a t a o f i n t e r e s t can be found

2 and 3 ) .

i n T a b l e 111. T h i s i s t h e w o r l d ' s most i m p o r t a n t known d e p o s i t o f s e p i o l i t e . 90% o f t h e w o r l d ' s known r e s e r v e s a r e f o u n d i n t h i s area. has been p u r i f i e d and processed, most o f i t i s e x p o r t e d . than 50 i n d u s t r i a l .uses.

More t h a n

Once t h i s s e p i o l i t e S e p i o l i t e has more

98

TABLE I 1 CHEMICAL ANALYSES O F S E P I O L I T E

1

2

3

4

63.10

60.60

60.10

59.18

1.08

1.73

3.74

1.85

0.27

0.62

0.85

0.65

23.80

22.45

20.60

23.40

0.49

0.40

0.44

0.52

0.09

0.16

0.71

0.25

0.21

0.58

1.40

0.58

10.88

13.22

11.95

12.60

99.92

99.21

99.83

99.03 ~

1,2,3;

Vallecas sepiolite,

d i f f e r e n t grades; 4:

Yunclillos

TABLE I 1 1 S E P I O L I T E DEPOSIT OF VALLECAS: Mineralogy

PROPERTIES A N D U S E S

Properties

Uses

Sepiol i t e

P o r o s i t y = 17%

Decoloring agents;

(up t o 95%)

Particle size:

absorbent granules;

Smec t it e s

8000 x 250 x 40A3

c a t 1i t t e r ; c a r r i e r s

I l l i t e

S p e c i f i c g r a v i t y :2 . 2

f o r i n s e c t i c i d e s and

Palygorskite

Shell Index:2.7

Calcite

2.7

Do1 o m i t e

Water a b s o r p t i o n

Kg/cm3

Kg/cm3

herbicides; dispersants;

saline d r i l l -

i n g muds;

rubber and

Quartz

(FORD) = 1 1 0 - 1 3 0 %

plastic industries;

Cristobal i t e

Specific surface:

asbestos substitute;

Feldspars

350 m2/g

cosmetic;

C.E.C.

= 26 meq/g.

ture.

agricul-

99

F i g . 8.- T r a n s m i s s i o n e l e c t r o n m i c r o g r a p h o f t h e V a l l e c a s - V i c b l v a r o s e p i o l i t e The Y u n c l i l l o s s e p i o l i t e d e p o s i t ( p r o v i n c e o f Toledo) S i t u a t e d 15 Km n o r t h o f t h e c i t y o f Toledo, i t s e x t e n t i s a p p r o x i m a t e l y

3 Km2.

I t a l s o forms p a r t o f t h e d e t r i t a l s u b f a c i e s i n t h e t r a n s i t i o n f a c i e s

o f t h e T a j o b a s i n , and i t s l o g i s shown i n F i g . 9.

One observes, as i n The upper i s o f

V a l l e c a s , t h e e x i s t e n c e o f two s e p i o l i t e - c o n t a i n i n g l a y e r s .

v a r y i n g c o m p o s i t i o n , c o n t a i n i n g n o t a b l e i m p u r i t i e s o f Mg-smectites,

and l a r g e

nodules o f c h e r t , i r r e g u l a r l y d i s t r i b u t e d , and occupying an i n t e r m e d i a t e p o s i t i o n i n t h e s e p i o l i t e bed.

The l o w e r l e v e l i s f a i r l y c o n t i n u o u s and pure

( F i g . 5, sample 4 and T a b l e 1 1 )

om 2m SEPDUTE-SMECTITE CLAY WITH CHERT

F i g . 9.- Log a t

0

SAND AND CLAYEY SAND

Yuncl i110 s , To1 edo

SEFIOLITE 12m Ism

20 m

ILUTE-SMECTITE &NO SEPlOLlTE

CLAY

ILLITE-SMECTITE CLAY

100 Other occurrences o f s e p i o l i t e and p a l y g o r s k i t e Magan T h e l i t h o s t r a t i g r a p h i c s e r i e s i n Magan ( p r o v i n c e o f T o l e d o ) i s f o r m e d by an a l t e r n a t i o n o f f i n e m i c a c e o u s sands and b e n t o n i t e c l a y s o f a saponite n a t u r e (see column 5,

Fig. 4).

Between t h e s e

c l a y s a r e t h i n l a y e r s o f s e p i o l i t e (maximum 5 0 c m ) .

The p u r i t y of

t h e s e p i o l i t e i s o n l y 50-70%, p r i m a r i l y because o f t h e presence of saponites.

These c l a y s a l s o b e l o n g t o t h e d e t r i t a l s u b f a c i e s o f

the Tajo basin t r a n s i t i o n facies.'They

can be s t r a t i g r a p h i c a l l y

correlated with the lower sepiolite exploited i n Yunclillos. San M a r t i n d e P u s a

-

Toledo

Microconglomerates o f q u a r t z and q u a r t z i t e s w i t h a cement formed o f p a l y g o r s k i t e and s m e c t i t e s w i t h c r i s t o b a l i t e o r carbona t e s have been d e s c r i b e d by Ordonez e t a l .

(1977a).

These a r e i n

t h e western sub-basin o f t h e T a j o ( T a l a v e r a de l a Reina) ( F i g .

2)

and a l s o n e x t t o t h e s o u t h e r n b o r d e r of

at

t h e c e n t r a l sub-basin,

t h e n o r t h o f t h e Toledo Mountains (San M a r t i n de Pusa, Puebla de Montalban, ces).

s o u t h of

i n t h e area surrounding Toledo and other pla-

These m a t e r i a l s have been d a t e d as d i f f e r e n t l y as Upper Cre-

taceous,

Paleocene,

Oligocene and Miocene,

according t o the loca-

tion. The e a s t e r n s u b - b a s i n o f t h e T a j o The c l a y m i n e r a l o g y o f T e r t i a r y m a t e r i a l s f r o m t h e e a s t e r n sub-basin outcrops between t h e A l t o m i r a S i e r r a and t h e I b e r i a n Range ( F i g .

2 ) have been s t u d i e d b y G a r c i a P a l a c i o s ( 1 9 7 7 ) .

ward t h e c e n t e r o f t h e sub-basin, dominate,

To-

Mg-smectites and s e p i o l i t e pre-

b u t t h e y do n o t a p p e a r t o g e t h e r . A l - s m e c t i t e s

and

p a l y g o r s k i t e appear more f r e q u e n t l y t h a n s e p i o l i t e on t h e b o r d e r s . Vertical mineralogical cycles occur i n t h i s sub-basin: c y c l e b e g i n s w i t h A1-Mg

(palygorskite, Al-smectite,

the

Al-Mg-smec-

t i t e ) a n d e n d s r i c h i n Mg ( M g - s m e c t i t e o r s e p i o l i t e ) . To t h e n o r t h o f t h i s s u b - b a s i n ,

close t o Tabladillo (province

o f Guadalajara) and between t h e g y p s i f e r o u s m a r l s o f t h e e v a p o r i t i c facies,

two l a y e r s o f p a l y g o r s k i t e have been d i s c o v e r e d

( M a r t i n Pozas e t a l .

1981).

Found i n t h e t o p o f t h e s e r i e s ,

they

101 a r e 0.4

a n d 2m t h i c k .

by s e p i o l i t e ( 1 0

-

The p a l y g o r s k i t e ( 6 6

20%), mica, quartz,

-

70%) i s accompanied

calcite,

d o l o m i t e and opal.

THE D U E R O B A S I N Lithology This vast basin l i e s i n the north central ian Peninsula (Fig.

region o f the Iber-

1) and c o i n c i d e s l a r g e l y w i t h t h e hydrographic The m a t e r i a l s t h a t f i l l t h e b a s i n a r e be-

basin o f t h e Duero r i v e r .

l i e v e d t o be o f t h e M i o c e n e age.

Three u n i t s a r e i n v o l v e d . They are,

from o l d e s t t o youngest: The Lower U n i t .

T h i s u n i t c o n s i s t s o f sandstones,

conglomerates

a n d s a n d s , w i t h some c l a y i n t e r l a y e r s , w h i c h b e c o m e m o r e a b u n d a n t f a r t h e r away f r o m t h e b o r d e r s o f t h e b a s i n . T h i s i s t h e u n i t w i t h the largest superficial

extension.

Toward t h e n o r t h - e a s t ,

t h i c k n e s s d e c r e a s e s t o a m i n i m u m o f 10 m e t e r s .

its

I n some p a r t s ,

un-

d e r n e a r t h t h i s d e t r i t a l l o w e r u n i t a p p e a r m a r l y m a t e r i a l s composed of white marls,

w i t h a n d w i t h o u t gypsum,

The M i d d l e U n i t . i s evaporitic,

and c l a y .

T h i s u n i t c a n b e d i v i d e d i n t o t w o b e d s . The l o w e r

f o r m e d o f l a y e r s o f gypsum ( w i t h l a r g e a r r o w h e a d -

shaped t w i n s ) and g y p s i f e r o u s m a r l s w i t h d o l o m i t e and s e p i o l i t e . The u p p e r ,

m a r l y bed i s composed o f an a l t e r n a t i o n o f l i m e s t o n e s ,

marls and calcareous c l a y s . A t t h e top,

a n a p p r o x i m a t e l y 1 cm

t h i c k "mountain l e a t h e r " p a l y g o r s k i t e c l a y l a y e r i s found,

w i t h an

irregular distribution. The U p p e r U n i t c o n s i s t s o f P o n t i a n l i m e s t o n e s Fig.

-

"Paramo l i m e s t o n e s " .

10 shows a s c h e m a t i c d i a g r a m o f t h i s b a s i n a n d v a r i o u s c o l u m -

nar sections which c o r r e l a t e t h e described materials. Sepiolite-palygorski t e occurrences

So f a r ,

no s e p i o l i t e - p a l y g o r s k i t e d e p o s i t s o f commercial

t e r e s t have been'found.

However,

minerals i n t h e Middle U n i t

-

a l s o c a l l e d "cuesta facies"

t o Aranda d e l Duero and T o r r e s a n d i n o ( P r o v i n c e o f Burgos), outskirts o f Valladolid,

in-

a series o f ' i n d i c a t i o n o f these

-

close i n the

i n Sacramenia ( p r o v i n c e o f Segovia),

have

been d e s c r i b e d ( G a r c i a d e l C u r a a n d L o p e z Aguayo 1974; O r d o n e z e t al.,

1977b;

Pozo a n d Carames,

1983; M a r t i n Pozas e t a l .

1983).

102 P a l y g o r s k i t e i s more abundant t h a n s e p i o l i t e and sometimes c o n s t i t u t e s a s much a s 9 0 % o f

the marly-clayey material.

The d o m i n a n t

carbonate i s dolomite. Lequey e t a l .

( t h i s volume) have r e p o r t e d t o t h e south-west

o f Segovia conglomerates w i t h D a l y g o r s k i t e cement w i t h c h a r a c t e r i s t i c s d i f f e r e n t from those o f the "cuesta facies"

and v e r y s i m i -

l a r t o t h e San M a r t i n d e P u s a m i c r o c o n g l o m e r a t e s . N

EXPLANATION UPPER UNIT L I M E S T M S . MARLS. CLAYS, GYPSUM, WRLS, U I T E

o

LOWER UNIT

l-

M,DDLE sp-po)

wRLr AND GYPSIFERRLS MATERIALS PALEOZOIC AND MESOZOIC ROCKS

F i g . 10.-

General diagram o f t h e Duero b a s i n and l i t h o s t r a t i g r a phic correlation

T H E EBRO B A S I N The s e d i m e n t o l o q i c a l c h a r a c t e r i s t i c s a r e s i m i l a r t o t h o s e o f the Tajo basin,

b u t i n t h e Ebro b a s i n t h e r e e x i s t s a d i s t i n c t

s t a q e o f m a r i n e s e d i m e n t a t i o n d u r i n g t h e Eocene epoch.

103 P a l y g o r s k i t e - s e p i o l i t e o c c u r r e n c e s have been d e s c r i b e d by P i n i l l a (1966), Alonso and Galvan (1961), (1974),

Alonso (1970),

Huertas e t a l .

and Gonzalez and Galan ( i n p r e s s ) b u t t h e m a t e r i a l s ana-

l y z e d do n o t h a v e t h e c h a r a c t e r i s t i c s r e q u i r e d t o b e m i n e d . Two f u n d a m e n t a l evaporitic facies

t y p e s o f m a t e r i a l s can be d i s t i n g u i s h e d : t h e

(gypsum,

anhydrite,

the marly-calcareous facies. stant.

halite,

etc.),

and above i t ,

Both a r e m i n e r a l o g i c a l l y very con-

I l l i t e p r e d o m i n a t e s among t h e c l a y m i n e r a l s . O c c a s i o n a l l y ,

s e p i o l i t e appears i n t h i n l a y e r s , contrast w i t h the Tajo basin,

b u t these a r e n o t continuous.

In

t h e Ebro b a s i n has no d e f i n e d t r a n s -

i t i o n facies. Generally speaking, investigation.

t h i s b a s i n has n o t undergone a d e t a i l e d

Only the Ablitas-Tarazona-Borja

area (province o f

Zaragoza) has been s t u d i e d r e c e n t l y ( G o n z a l e z and Galan, aration).

i n prep-

R e l a t i v e l y i m p o r t a n t l a y e r s composed o f s e p i o l i t e a n d

t r i o c t a h e d r a l smectites w i t h carbonates and d e t r i t a l i l l i t e ,

have

been i d e n t i f i e d i n t h i s a r e a .

T H E GUADALQUIVIR B A S I N The Neogene c l a y d e p o s i t s o f t h i s b a s i n a r e e s s e n t i a l l y o f m a r i n e o r i g i n . Only v e r y r a r e l y do f i b r o u s c l a y m i n e r a l s a p p e a r . However,

near t h e Guadalquivir o u t l e t (Fig.

1 1 ) t h e r e i s an impor-

t a n t p a l y g o r s k i t e m a r l d e p o s i t i n l a c u s t r i n e P l i o c e n e which has been s t u d i e d b y G o n z a l e z G a r c i a a n d P e i r o ( 1 9 5 8 ) .

Huertas e t a l .

(19741, and Galan and F e r r e r o ( 1 9 8 2 ) . The L e b r i j a p a l y g o r s k i t e - s e p i o l i t e d e p o s i t The U p p e r P l i o c e n e s e d i m e n t s n e a r L e b r i j a ( p r o v i n c e o f Sev i l l a ) c o n t a i n commer'cial

d e p o s i t s o f p a l y g o r s k i t e and s e p i o l i t e .

Two u n i t s c a n b e d i s t i n g u i s h e d i n t h e c o n t i n e n t a l P l i o c e n e : a " m a r l y - c a l c a r e o u s bed" a n d an u p p e r " p a l y g o r s k i t e bed".

The b a s e

o f the lower u n i t i s usually a s i l i c i f i e d limestone o r a limestone with chert (white o r gray),

b u t i n c e r t a i n places,

d i a t o m i t e forms

t h e base o f t h e P l i o c e n e . The " m a r l y - c a l c a r e o u s limestone,

bed" i s 25-30 m t h i c k and c o n s i s t s o f

m a r l y and sandy l i m e s t o n e , marl and c l a y e y marl,

i n t e r b e d d e d t h i n beds ( u p t o 1 m t h i c k ) o f d a r k brown,

with

l i g h t brown

or p i n k i s h w h i t e m a r l y c l a y named " T i e r r a d e l V i n o " ( w i n e e a r t h ) , b e c a u s e t h e m a t e r i a l f o r m e r l y was u s e d t o c l a r i f y a r l d p u r i f y w i n e . The u p p e r u n i t (

1 5 m t h i c k ) i s named t h e " p a l y g o r s k i t e b e d "

104 because o f i t s h i g h content o f p a l y g o r s k i t e . range from 30 cm t o 3 m i n thickness.

The p a l y g o r s k i t e l a y e r s Limestone layers a r e interbedded i n

this unit.

A g r e a t abundance o f microfauna was noted i'n these calcareous m a t e r i a l s , which a r e c h a r a c t e r i s t i c o f brackish f a c i e s o r swamp o f t h e Upper Pliocene o r Quaternary.

Pa

WLYMRSKITE

Sp

SEPiULlTE

I

ILLITE

Sm

SYECTITE

EXPLANATION MIL N W A M LIIIE8TOfIF WLYGORSIIITE C L m

WINE PL-

-

W L M R S K I T E MARL

ALLOCHTHONOUS YATERIAIs

0

cmss

@ SANDY

SECTO IN

CLAYEY S4NC LIHSTONE

h?kY&g:zy

@ LIMESTONE TIERRA CEL VlNO

Fig. 11.-

Location o f the L e b r i j a p a l y g o r s k i t e - s e p i o l i t e deposit, crosss e c t i o n SW-NE across t h e Mesa del Cuervo and Laguna de 10s T o l l o s , and the s t r a t i g r a p h i c column ( a f t e r Galan and Ferrero, 1982).

105 The " T i e r r a d e l V i n o " a r e t y p i c a l l y 5 0 % c a l c i t e a n d 50% s e p i o l i t e , with minor smectite,

p a l y g o r s k i t e and q u a r t z .

neral suites e x i s t i n the lower u n i t :

Three clay-mi-

sepiolite + palygorskite i n

the bottom; s e p i o l i t e + palygorskite f i l l i t e i n t h e center,

and

palygorskite + i l l i t e f s e p i o l i t e f smectite i n t h e upper part. I n t h e p a l y g o r s k i t e bed, skite + i l l i t e (Fig.

t h e main clay-mineral

s u i t e i s palygor-

P a l y g o r s k i t e v a r i e s from'35 t o 75% i n

11).

t h e c l a y and m a r l l a y e r s . THE TORREJON B A S I N The T o r r e j o n e l R u b i o b a s i n ( p r o v i n c e o f C a c e r e s ) s t a n d s o u t among t h e S p a n i s h - P o r t u g e s e T e r t i a r y b a s i n s w i t h f i b r o u s c l a y m i n e r a l s because o f i t s g r e a t abundance o f p a l y g o r s k i t e . t a n t d e p o s i t was d i s c o v e r e d i n t h e e a r l y 1 9 6 0 ' s ,

This impor-

b u t these marly

p a l y g o r s k i t e s have been used l o c a l l y as whitewash s i n c e a n c i e n t times.

T h e e x i s t e n c e o f t h e d e p o s i t was p o i n t e d o u t b y A l v a r e z

E s t r a d a a n d Sanchez Conde ( 1 9 6 7 ) . al.

I t has been s t u d i e d b y Galan e t

(1975) and reviewed by Galan e t a l .

(1982).

Geologic S e t t i n g The T e r t i a r y b a s i n o f T o r r e j o n e l Rubio ( F i g . a p p r o x i m a t e l y 250 Km2, imum l e n g t h o f 3 7 Km.

12) occupies

and g e n e r a l l y extends east-west,

w i t h a max-

The base c o n s i s t s o f Cambrian s l a t e s o f t h e

I b e r i a n M a s s i f . To t h e n o r t h a n d n o r t h - e a s t

o f t h e b a s i n i s an i m -

p o r t a n t q u a r t z i t e r e l i e f ( t h e Corchuelas, M i r a v e t e and t h e Extranj e r a S i e r r a s ) w h i c h now s e p a r a t e s t h e b a s i n f r o m t h e T a j o b a s i n . To t h e s o u t h a n d s o u t h - e a s t

a r e two e x t e n s i v e outcrops o f Hercynian

granites surrounded by aureoles o f cornubianites. The basement i s a f f e c t e d by two systems o f H e r c y n i a n f r a c t u r e s running north-eas

-

south-west and south-east

- northwest.

The

f o r m a t i o n o f t h i s t e c t o n i c t r o u g h appears r e l a t e d t o t h e second s e t o f fractures,

due t o r e a c t i v a t i o n s d u r i n g t h e Miocene which c o n t i n -

ued d u r i n g t h e f i l i n g o f t h e basin. Lithology From b o t t o m t o t o p , basement,

t h r e e u n i t s can be d i s t i n g u i s h e d : a ) t h e

b ) t h e d e t r i t a l - c l a , y e y bed, and c ) t h e "rana".

Rana i s a

S p a n i s h t e r m f o r a c o n s o l i d a t e d mudf1o.w d e p o s i t c o n t a i n i n g a n g u l a r blocks o f rock o f a l l sizes,

e.g.

a fanglomerate.

OUARZITE SLbTE (BASEMENT!

ST-3LISrLOG NUMBER

?

MINE

319: ELEVATION IN M

Fig.12.-

Flap s h o w i n q l i t h o l o i i c u n i t s o f T o r r e j 6 n b a s i n a n d r e v r e s e n t a t i v e 1 0 7 s . P a = P a l y g o r

.

I=Illite

107 The b a s e m e n t c o n s i s t s o f b r o w n i s h - p i n k i s h c l a y e y s l a t e s w i t h d i s s e m i n a t e d p y r i t e a n d s m a l l d i k e s o f m i l k y q u a r t z . An a l t e r a t i o n o f t h e s l a t e s t o w h i t i s h and g r e e n i s h c l a y s can be observed i n t h e

upper p a r t o f t h i s basement.

T h i s a l t e r a t i o n d o e s n o t a p p e a r when

r e s t s d i r e c t l y on t h e basement.

the "rana"

The c l a y e y - d e t r i t a l and g r a v e l s ,

b e d i s made u p o f a n a l t e r n a t i o n o f s a n d

w i t h c l a y s more o r l e s s r i c h i n q u a r t z and c a r b o n a t e s .

The l e v e l s a r e l e n s - s h a p e d a n d o f r e l a t i v e l y c o n s t a n t t h i c k n e s s , v a r y i n g a r o u n d 0.7m. 3 m thick,

alteration, zone). zone.

I n t h e base one o b s e r v e s a c l a y e y bed,

0.3

-

which contains r e l i c t i c s l a t e w i t h d i f f e r e n t grades o f more abundant t o w a r d t h e w a l l

( t h e basement a l t e r a t i o n

T h e maximum t h i c k n e s s c o i n c i d e s w i t h t h e l o w e s t t o p o g r a p h i c A t t h e t o p one f i n d s a c o n t i n u o u s sandy l a y e r o f v a r y i n g

thickness (0.15

-

1.5 m).

The t o t a l t h i c k n e s s o f t h i s b e d v a r i e s

between 6 a n d 5 0 m. The t h i r d b e d ,

the "rana"

( L a t e Miocene - Pliocene) i s a red-

dish fanglomerate o f q u a r t z i t e pebbles which occupies the topographically higher levels o f the basin.

It occurs w i t h greater f r e -

quency i n t h e s o u t h e r n a n d s o u t h - w e s t e r n "

borders and c r e a t e s a

me s a "

Mineralogy The s l a t e s a r e composed o f q u a r t z , ites of the sheridanite-clinochlore tites,

f e l d s p a r s , micas and c h l o r -

type,

w i t h k a o l i n i t e , smec-

g o e t h i t e and p y r o p h i l l i t e o c c a s i o n a l l y present.

I n the al-

t e r e d s l a t e s t h e m i n e r a l o g i c a l a s s e m b l a g e i s t h e same a s i n t h e previous,

together with palygorskite,

i n t e r s t r a t i f i e d clay minerals

and dolomite. The c l a y e y - d e t r i t a l or palygorskitic,

bed has two zones.

The l o w e r ( 0 . 5

has t h e f o l l o w i n g assemblage:

i l l i t e f s m e c t i t e k c h l o r i t e f s e p i o l i t e (Pa + I b e i n g Pa

>

I; w h i l e t h e u p p e r , o r i l l i t i c ,

same a s s e m b l a g e , smectites.

but with I

>>

-

4 m),

Palygorskite +

*

Sm

*

Ch

_+

Sp),

i s c h a r a c t e r i z e d by t h e

Pa, a n d t h e c o n s t a n t p r e s e n c e o f

The o t h e r components a r e q u a r t z ,

The s m e c t i t e s a r e o f s a p o n i t e t y p e .

f e l d s p a r s and dolomite.

P a l y g o r s k i t e c o n t e n t can

r e a c h 70%. T a b l e I V d e s c r i b e s t h e m i n e r a l o g i c a l c o m p o s i t i o n s .

Table

V i n c l u d e s r e p r e s e n t a t i v e a n a l y s e s o f t h e basement and t h e a l t e r a t i o n zone as w e l l a s t h e p a l y g o r s k i t e and i l l i t e zones.

I n t h e pa-

l y g o r s k i t e z o n e a g r a n u l o m e t r i c d i f f e r e n t i a t i o n c a n b e made b e t w e e n the t o p and bottom.

'TABLE I V

2

0

W

MINERALOGICAL COMPOSITION OF TORREJ9N MATERIALS

Illitic zone

Palygorski te zone

Values

Q

Range

15-35

1nd.-30

25-55

Ind. -20

Norm

20-25

15-2.0

35-40

10

Range

10-45

35-70

1nd.-15

0-15

Norm

30-40

45-50

10

5-45

25-45

25-5

Pa

I1

Sm

Ch-K

Ind. - 1 0

F

Do

0-10

0-15 very little

5

1nd.-5

0

0-5

0-5

0-60

Ind.

Ind.

0-20

5-20

1nd.-5

little

Range

5

10-Ind.

0-40 little

A1 teration zone

Ca-Cb-Sp

Norm

25-30

30-40

10-15

Range

15-40

-

25-35

Norm

25-30

-

25-30

Slate

5-10

Ind.

Ind-5

10-50

5-1 5

Ind

30-35

10

5

Q = Quartz; Pa = Palygorskite; I1 = Illite; Sm = Smectite; Ct, = Chlorite; K = Kaolinte; F = Feldspars; Do = Dolomite; Ca = Calcite, Cb = Cristobalite; Sp = Sepiolite; Ind = Traces.

0

109 TABLE

V

REPRESENTATIVE CHEMICAL ANALYSES OF TORREJON MATERIALS AFTER HEATING AT 1000°C Slate

A1 t e r a t i o n zone

Pa zone

I 1 zone

Bottom -Top Si02

72.98

73.23

75.86

-

73.77

62.19

A1203

14.49

13.70

10.12

-

12.18

19.94

Fe203

4.14

'4.74

3.78

-

4.43

7.88

MgO

4.14

4.36

7.78

-

7.0

4.18

CaO

0.52

0.46

1.0

-

0.9

0.96

Na20

1.56

1.52

0.33 -

0.33

0.43

K20

2.28

1.98

1.11 -

1.38

4.39

H20t

3

5

9.5

9

7

(average)

TABLE

VI

THE TORREJON PALYGORSKITE DEPOSIT Mineralogy P a l y g o r s k i t e (up t o 85%) Quartz Feldspars

Chemistry ( X ) Si02:51 .5 A1 203: 10.03 Fe203: 2.36

Do1 omi t e Calcite

C r i stobal it e Saponi t e Illite Sepiol i t e Kaol i n i t e Chlorite Org. Mat.

FeO: 0.52 Mg0:12.28 H20+:14.43 -

H20-: 7.36

Properties o f Palygorskite

Uses

P a r t i c l e size: 0 . 5 - 4 . 5 ~ long 150-300 8 t h i c k

F l o o r absorbents Carriers for insecticides

C.E.C*=26.5 meq/g S p e c i f i c surface:

D r i l l i n g i n saline waters.

146 m2/g

110

The f o l l o w i n g p o i n t s a r e i m p o r t a n t f o r u n d e r s t a n d i n g t h e s e a n a l y s e s : a ) Si02 c o n t e n t remains c o n s t a n t f r o m t h e s l a t e t o t h e t o p o f t h e p a l y g o r s k i t e zone, w h i l e i t d i m i n i s h e s i n t h e i l l i t i c ; b ) w i t h r e s p e c t t o t h e e n t i r e c l a y e y - d e t r i t a l bed, A1203 d i m i n i s h e s i n t h e p a l y g o r s k i t e zone and i n c r e a s e s c l e a r l y i n t h e i l l i t i c ; c ) t h e MgO remains c o n s t a n t , except i n t h e p a l y g o r s k i t e zone, where i t i n c r e a s e s ; d ) Na20 and K20 decrease a l o n g t h e a l t e r a t i o n and t h e p a l y g o r s k i t e zones, i n c r e a s i n g a g a i n i n t h e i l l i t i c , e s p e c i a l l y K20; and e ) Fe203 a l s o i n c r e a s e s i n t h e i l l i t i c zone. F i g . 13 shows d i f f r a c t o g r a m s o f t h e d i f f e r e n t t y p i c a l m i n e r a l o g i c a l a s s o c i a t i o n o f t h e d e s c r i b e d beds.

T a b l e V I c i t e s some o f t h e c h a r a c t e r i s t i c s

o f t h e e x p l o i t e d p a l y g o r s k i t e (Galan e t a l . 1975; Galan, 1979).

0

2

F i g . 13.

-

X-ray powder d i f f r a c t i o n p a t t e r n s o f c h a r a c t e r i s t i c m a t e r i a l s of t h e T o r r e j o n b a s i n . 1.- S l a t e (basement), 2.- A l t e r a t i o n zone on s l a t e , 3.- P a l y g o r s k i t e zone, 4.-

I l l i t e zone.

Pa=Palygorskite,

I = I 1 1 it e , K=Kaol i n i t e , M=Mica, C l = C h l o r i t e , Q = Q u a r t z , F=Feldspars , Do=Dolomite, Cu K r a d i a t i o n .

111 MISCELLANEOUS I n G a l i c i a a n d A s t u r i a s t h e r e a r e a number o f s m a l l T e r t i a r y t e c t o n i c b a s i n s commonly f i l l e d w i t h c o n t i n e n t a l s e d i m e n t s o f e s s e n t i a l l y k a o l i n i t i L nature. (Roupar,

However,

i n three o f these basins

Puentes de Garcia Rodriguez and S a r r i a ) ,

s l a t e basement,

w h i c h r e s t on a

p a l y g o r s k i t e m a r l s w i t h s e p i o l i t e and i l l i t e have

been d e s c r i b e d ( i u c a s e t a l .

1963, B r e l l ,

1972; B r e l l and Doval,

1974). I n t h e d e p r e s s i a n s o f Granada,

Gorafe-Huelago,

and Guadix-Baa,

p a l y g o r s k i t e h a s b e e n f o u n d o n l y i n some s t a g e s o f l a c u s t r i n e f a cies, mixed w i t h smectite, (Huertas e t a l .

1974;

i l l i t e , and o t h e r d e t r i t a l m i n e r a l s

Sebastian e t a l .

To t h e n o r t h - e a s t o f Granada,

1975,

1979).

i n the Middle Subbetic,

bento-

n i t e s have been found t o c o n s t i t u t e a p a r t o f t h e Fardes Formation (Early Cretaceous),

formed by t h e weathering o f volcanic rocks.

S i g n i f i c a n t q u a n t i t i e s o f palygorskite are found together w i t h the smectites.

The g e n e s i s o f b o t h m i n e r a l s f r o m t h e s e v o l c a n i c r o c k s

has been s t u d i e d b y S e b a s t i a n e t a l .

(1982).

I n t h e T e r t i a r y b a s i n o f t h e Mancha, nce o f Ciudad Real),

close t o Daimiel

M a r t i n Pozas a n d M a r t i n V i v a l d i

(provi-

(1981) have

found t r a c e s of p a l y g o r s k i t e a s s o c i a t e d w i t h s m e c t i t e ,

i l l i t e and

kaol i n i t e .

So f a r ,

no i n d i c a t i o n s o f t h e s e m i n e r a l s have been found i n

the T e r t i a r y basin o f Badajor o r Levante. I n t h e T e r t i a r y o f t h e Cuevas o f A l m a n z o r a and Vera

o f Almeria),

(province

p e r i m a r i n e p a l y g o r s k i t e m a r l s have been found ( u p t o

20% p a l y g o r s k i t e ) w i t h i n d i c a t i o n s o f s e p i o l i t e , smectites and i l l i t e (Galan e t a l .

i n

together with

preparation).

I n other areas

o f t h e Almeria T e r t i a r y (between Sorbas, Tabernas and Garucha), palygorskite i s frequently found i n the marly materials. Finally,

i n the T e r t i a r y basin o f Calatayud-Teruel,

c i t y o f Teruel,

near the

t h e e x i s t e n c e o f p a l y g o r s k i t e has been n o t e d i n t h e

smectitic marls.

As a m i n e r a l o g i c a l c u r i o s i t y , o n e n o t e s t h a t M a r t i n V i v a l d i and L i n a r e s ( 1 9 6 2 ) m e n t i o n e d " a random i n t e r g r o w t h o f s e p i o l i t e a t t a p u l g i t e " i n t h e b e n t o n i t e d e p o s i t s o f t h e vo c a n i c r e g i o n o f Cab0 de G a t a ( p r o . v i n c e o f A l m e r i a ) .

D I S C U S S I O N A N D CONCLUSIONS The d e s c r i b e d T e r t i a r y d e p o s i t s w i t h s e p i o l t e o r p a l y g o r s k t e

112 are c l e a r l y o f a continental character.

These m i n e r a l s do n o t ap-

pear i n connectio-n w i t h any v o l c a n i c a c t i v i t y , t h e r m a l phenomena.

n o r w i t h any hydro-

The a c c u m u l a t i o n o f t h e s e m i n e r a l s i s n o t con-

t r o l l e d by tectonics.

On t h e c o n t r a r y ,

t h e i r s t r a t i f o r m morphology

and t h e i r p o s i t i o n w i t h r e l a t i o n t o o t h e r sedimentary m a t e r i a l s suggests an o r i g i n i n c l o s e d c o n t i n e n t a l sedimentary basins ( l a c u s t r i n e environment),

o r a n o r i g i n w i t h r e s t r i c t e d sea w a t e r c i r -

c u l a t i o n (perimarine environment;

lagoons,

swamps,

t i d a l zones,

etc.). The d e p o s i t s i n S p a i n c a n b e d i v i d e d i n t o f o u r g r o u p s b a s e d on t h e i r g e o l o g i c a l s e t t i n g and m i n e r a l o g y :

2) Torrejon type, b r ij a type.

1) Tajo basin type,

3 ) B e n f i c a - S a n M a r t i n d e Pusa t y p e ,

and 4) Le-

The c h a r a c t e r i s t i c s o f each t y p e a r e d e s c r i b e d b e l o w .

1 ) T a j o b a s i n t y p e (sepiolite-palygorskite-Mg-smectite d e p o s i t s ) . The s e d i m e n t a t i o n b a s i n i s a t e c t o n i c d e p r e s s i o n o f v a r y i n g dimensions,

s i t u a t e d i n a c r a t o n i c area.

The s u r r o u n d i n g a r e a s a r e

made u p o f a c i d i c r o c k s ( p l u t o n i c a n d / o r m e t a m o r p h i c ) a n d c a l c a r eous r o c k s .

They u n d e r w e n t w e a t h e r i n g a f t e r a l i g h t u p l i f t ( o r

progressive sinking o f t h e basin). This process supplied the basin w i t h d e t r i t a l materials and ions i n solution, ning waters. areas,

transported by run-

The c o a s e r d e t r i t a l s were d e p o s i t e d i n t h e m a r g i n a l

while f i n e d e t r i t a l sediments ( d e t r i t a l

t r a n s i t i o n subfa-

c i e s ) were i n t h e d i s t a l zones o f t h e a l l u v i a l f a n s .

In the typi-

c a l l y l a c u s t r i n e zones an e v a p o r i t i c s e d i m e n t a t i o n w i t h v e r y f i n e grained materials,

such as c l a y s ( m a r l y t r a n s i t i o n s u b f a c i e s and

m a r l y e v a p o r i t i c f a c i e s ) was p r o d u c e d . T h e p r e c i p i t a t i o n o f a u t h i genic c l a y minerals mainly r e s u l t e d i n a playa-lake environment during a period o f t e c t o n i c calm (Fig.

14).

The m i n e r a l o g y o f t h e s e s e d i m e n t s i s composed o f i n h e r i t e d minerals (quartz, feldspars,

micas,

kaolinite, chlorite,

diocta-

hedral smectites) and authigenic minerals ( c a l c i t e , dolomite, sum,

palygorskite,

sepiolite,

saponite,

stevensite).

i n t e r m e d i a t e phases ( t r a n s f o r m e d m i n e r a l s ) appear (e.g.

r illite-smectite,

gyp-

Some a l t e r e d mixed-

or illite-chlorite).

The i n h e r i t e d m i n e r a l s d o m i n a t e t h e d e t r i t a l f a c i e s ,

while

a u t h i g e n i c ones a r e more f r e q u e n t i n t h e more d i s t a l zone o f lake-shore area.

Nevertheless,

with the clastic material authi-

c m i n e r a l s can a l s o be p r e c i p i t a t e d . The p r e c i p i t a t i o n o f c a l c i t e o r d o l o m i t e

-

unlike that of

113 sepiolite tors,

-

depends on t h e p a r t i a l Dressure of

such as t h e e n v i r o n m e n t a l temperature,

organic catalysts, man,

C02, a n d o t h e r f a c -

evaporation,

salts,

and t h e nresence o f s u l n h a t e s and c h e r t ( L i p D -

1779; V e n i a l e e t a l .

1982; Baker and K a s t n e r ,

1381).

.ITE

MUD

A L L U V I A L FAN

Fin.

1p.-

FLAT

Slock d i a n r a i showinn t h e sedimentary environment i n t h e Tajo basin during s e p i o l i t e formation

The i n h e r i t e d c l a y m i n e r a l s a r e m o s t l y i l l i t e a n d d i o c t a h e d r a l s m e c t i t e s . The a u t h i q e n i c m i n e r a l s a r e M q - r i c h s i l i c a t e s , d i c a t e s t h a t t h e y w e r e f o r m e d i n S i 0 2 a n d '1'19-rich

which

it+

environment w i t h

l e s s e r n u a n t i t i e s o f A l . A c c o r d i n g t o t h e d a t a on t h e s y n t h e s i s and s t a b i l i t y o f s e p i o l i t e , 1962; W o l l a s t e t a l .

~ a l y q o r s k i t ea n d s t e v e n s i t e ( S i f f e r t ,

1368; S i n g e r and N o r r i s h ,

1977 a n d 1 9 7 8 ; IKhoury e t a l .

1782; e t c . ) ,

should o s c i l l a t e between 8 and 9. o f s e n i o l i t e i s favored,

on t h e a v a i l a b l e e d w h e r e t h e nH

quantity

I n pH 8

1 7 7 4 ; La I g l e s i a ,

t h e pH o f t h e s e s o l u t i o n s

-

8.5,

the precipitation

as w e l l as t h a t o f p a l y q o r s k i t e , depending o f ,Al.

Smectite precinitation i s favor-

3. The l a t e r a l c h a n g e s i n t h e r a t i o s o f t h e s e m i -

n e r a l s d e D e n d p r i m a r i l y o n t h e l o c a l pH a n d t h e a v a i l a b l e A l . excess s i l i c a of

precipitates

m a s s i v e l y a s c h e r t (C-T

The

o p a l ) when a l l

t h e l o c a l Vq h a s b e e n c o n s u m e d .

A t l e a s t two s e p i o l i t e - r i c h aDoear i n t h e T a j o b a s i n .

enisodes (an upner and a l o w e r )

They a r e a s s o c i a t e d w i t h t h e d e t r i t a l

f a c i e s o f t h e d i s t a l zones o f a l l u v i a l f a n s ( d e t r i t a l s u b f a c i e s ) . I n the Vallecas-Vicilvaro

deposit,

the sepiol i t e o f the lower level

i s p o o r l y c r y t a l l i z e d and i s c o n t a m i n a t e d b y Mq-smectites. associated w i t h d o l o m i t i c l e v e l s and c h e r t .

I n contrast,

It i s

the sepio-

l i t e o f t h e u p p e r l e v e l a p p e a r s w e l l - o r d e r e d a n d w i t h l e s s Mg-smect i t e contamination.

I n this level,

calcite andlor chert,

the s e p i o l i t e i s associated with

These s i g n i f i c a n t m i n e r a l o g i c a l and c r y s t a l -

114 l o g r a p h i c d i f f e r e n c e s can be e x p l a i n e d by geochemical changes d u r i n g s e d i mentation.

D u r i n g t h e s e d i m e n t a t i o n process o f t h e l o w e r l e v e l t h e average

pH must have been 9, w i t h an excess o f Mg w i t h r e s p e c t t o s e p i o l i t e s a t u r a t i o n . I n t h e second case i t appears c l e a r t h a t Mg was l e s s abundant and t h a t t h e pH was l o w e r , 8.5, w i t h c o n d i t i o n s i d e a l f o r t h e s l o w c r y s t a l l i z a t i o n o f o r d e r e d s e p i o l it e . I n the marly subfacies, the authigenic minerals a r e g e n e r a l l y o f g r e a t e r c r y s t a l l i n i t y than those o f the d e t r i t a l subfacies.

I n a d d i t i o n , aluminium i s

more abundant ( p a l y g o r s k i t e i s more f r e q u e n t ) which, c o n s i d e r e d i n c o n j u n c t i o n w i t h t h e g r e a t e r abundance o f carbonates makes one t h i n k t h a t t h e s e m a t e r i a l s were produced s l o w l y , and w i t h physico-chemical c o n d i t i o n s i d e a l f o r growth (La I g l e s i a , 1977, 1978). 2)

Torrejon type ( p a l y g o r s k i t e deposits) During the Alpine orogenesis i n the I b e r i a n peneplain, north-west

-

s o u t h - e a s t H e r c y n i a n f r a c t u r e s were r e a c t i v a t e d , a l l o w i n g t h e c r e a t i o n o f s m a l l depressions i n t h e s l a t e basement. i n t e r m i t t e n t lakes.

Running w a t e r f i l l e d t h e s e b a s i n s , c r e a t i n g

O x i d a t i o n o f t h e abundant p y r i t e a p p e a r i n g i n t h e s l a t e

caused t h e a c i d i t y o f t h e s t a n d i n g w a t e r t o i n c r e a s e .

These s l i g h t l y a c i d i c

waters s u p e r f i c i a l l y d i s s o l v e d t h e s l a t e s , r e l e a s i n g a l k a l i n e and ferro-magn e s i a n elements, e s p e c i a l l y f r o m micas and c h l o r i t e s , and a l k a l i n i z i n g t h e environment. Under t h e s e c o n d i t i o n s , degraded micas ( K - d e f i c i e n t ) and c h l o r i t e s p r o b a b l y w i t h t h e b r u c i t i c l a y e r s i m p a i r e d and t h e o c t a h e d r a l l a y e r s p a r t i a l l y d e f e c t i v e , tended t o e q u i l i b r a t e , f i x i n g magnesium and r e c r y s t a l l i z i n g as p a l y g o r s k i t e o r s m e c t i t e s , a c c o r d i n g t o t h e pH and t h e a v a i l a b i l i t y o f Mg. S i n c e t h e o v e r a l l chemical c o m p o s i t i o n o f t h e a l t e r a t i o n zone i s s i m i l a r t o t h a t o f t h e s l a t e s w h i c h c o n t a i n s i g n i f i c a n t q u a n t i t i e s o f c h l o r i t e (“20%), i t i s n o t necessary t o suppose any o u t s i d e s u p p l i e s d u r i n g t h e a p p a r e n t

t r a n s f o r m a t i o n (by f i e l d c r i t e r i a ) , and one can assume t h a t t h e t r a n s f o r m a t i o n occurred i n a

c l o s e d system.

Only t h e decreases o f Na and K i m p l y an

a l t e r a t i o n o f f e l d s p a r s and muscovites and an a b s o l u t e l o s s i n t h e s e elements. The 2 : l u n i t s o f c h l o r i t e c o u l d a c c e p t Mg.

However, s i n c e t h e p a l y g o r s k i t e

a t t h e b o t t o m o f t h e p a l y g o r s k i t e zone has a magnesium-aluminium r a t i o s i m i l a r t o t h a t o f the c h l o r i t e i n the s l a t e o f

115 t h e basement, a g e n e t i c a l

r e l a t i o n s h i p between t h e s e two m i n e r a l

t y p e s c o u l d b e c o n j e c t u r e d b y m e a n s o f a n i n t r o d u c t i o n o f Mg i n 2:l

(di-trioctahedral)

A mechanism i s

incomplete c h l o r i t e units.

proposed whereby p a r t o f t h e t e t r a h e d r a l l a y e r would i n v e r t p e r i o dically,

so as t o a d a p t t o an i n c o m p l e t e o c t a h e d r a l l a y e r , g i v i n g

a palygorskite rather than a saponite structure. o f Mg a t h i g h e r pH w o u l d p r o d u c e s a p o n i t e .

A local increase

Interstratified chlorite

s m e c t i t e and i l l i t e - s m e c t i t e have been observed as i n t e r m e d i a t e stages. The f o r m a t i o n o f p a l y g o r s k i t e b y means o f t r a n s f o r m a t i o n o f s m e c t i t e s h a s b e e n s u g g e s t e d b y Weaver a n d Beck ( 1 9 7 7 ) a n d b y T r a u t h (1974). They d e s c r i b e a s i m i l a r mechanism, b u t w i t h o u t g i v i n g s u f f i c i e n t evidence.

Galan and F e r r e r o (1982) have described t h e

f o r m a t i o n o f p a l y g o r s k i t e b y means o f t h e t r a n s f o r m a t i o n o f i l l i t e i n a s i m i l a r manner.

I n a l l explanations,

t h e Mg i s i n t r o d u c e d f r o m

outside t h e system. Recent s t u d i e s (Galan,

i n preparation)

have demonstrated

t h a t t h e s l a t e basement o f t h e T o r r e j o n b a s i n can a l t e r i n t o s e p i o l i t e and s a p o n i t e .

T h e e x p e r i m e n t was c o n d u c t e d b y a t t a c k i n g t h e

s l a t e w i t h an a c i d i c s o l u t i o n (pH=3.1, teen days, week.

a d j u s t e d w i t h HC1) f o r f o u r -

a n d t h e n a l k a l i n i z i n g w i t h Mg(OH)2 ( p H = 9 . 5 )

f o r one

T h e f i l t r a t e c o n t a i n e d t h e same q u a n t i t y o f q u a r t z a n d f e l d -

spars as t h e s l a t e ;

c h l o r i t e d e c r e a s e d f r o m 30% t o 15%; m i c a s d e -

c r e a s e d f r o m 25% t o 20%; a n d s e p i o l i t e a n d s m e c t i t e appear, approximate c o n c e n t r a t i o n o f 10% and 15%, r e s p e c t i v e l y . p e c t e d t h a t new e x p e r i m e n t s w i t h l o w e r - p H

(e.g.

8.5)

a t an

It i s ex-

and lower pro-

p o r t i o n s o f Mg w i l l a l s o demonstrate t h e p o s s i b i l i t y o f p a l y g o r s k i t e genesis, (Galan e t a l .

a s has been proposed h e r e f o r t h e T o r r e j o n b a s i n 1982).

I n t h e s p e c i f i c case o f t h i s b a s i n and i n o t h e r s o f t h e western area o f t h e I b e r i a n peninsula,

one assumes t h a t t h e g r a d u a l

growth o f t h e b a s i n and f o r m a t i o n o f t h e t r o u g h a l l o w e d t h e t r a n s portation and accumulation o f d e t r i t a l materials i n various states o f degradation and o f i o n s i n s o l u t i o n , lines.

such as S i ,

Mg a n d a l k a -

By m e a n s o f t h e s e e l e m e n t s a n d t h e d e t r i t a l p h y l l o s i l i c a t e s

i n d i s e q u i l i b r i u m w i t h t h e medium p a l y g o r s k t t e c o u l d be formed. A u t h i g e n i c p a l y g o r s k i t e c o u l d a l s o have been p r e c i p i t a t e d f r o m t h e f r e e A1 a n d w i t h t h e e x c e s s S i a n d Mg o f t h e m e d i u m ( G a l a n e t a l . 1 9 7 5 ) . Mg a n d S i c a n o c c a s i o n a l l y f o r m p a r t o f d o l o m i t e a n d c r i s t o b a l it e ,

r e s p e c t i v e 1y .

P a l y g o r s k i t e formed by t r a n s f o r m a t i o n i n t h e blocks a d j a c e n t

116 t o t h e l o w e s t zone o f t h e b a s i n c o u l d have been removed d u r i n g t h e p r o g r e s s i v e s i n k i n g o f t h e -basin and sedimented w i t h o t h e r d e t r i t a l m a t e r i a l s . The b a s i n was capped by an i l l i t i c bed, o r i g i n a t e d f r o m m a t e r i a l s r i c h i n m u s c o v i t e and low i n c h l o r i t e and p a l y g o r s k i t e f r o m areas c l o s e t o t h e b a s i n which underwent an a c i d i c a1 t e r a t i o n b u t n o t a t r a n s f o r m a t i o n t o p a l y g o r s k i t e . T h i s happened d u r i n g t h e l a s t phase o f t e c t o n i c a c t i v i t y ( a t t h e l o c a l s c a l e ) , d u r i n g which s e d i m e n t a t i o n r e f l e c t s c o n d i t i o n s o f g r e a t e r calm.

The v e l o c i t y

of s e d i m e n t a t i o n must have been g r e a t e r t h a n t h a t o f t h e s i n k i n g o f t h e basement

.

A f t e r t h e " r a n a " , w h i c h was a r e g i o n a l episode, and t h r o u g h t h e a c t i o n o f p e r c o l a t i n g w a t e r r i c h i n i r o n , a p a r t i a l f e r r i t i z a t i o n o f t h e i l l i t i c bed and s m e c t i z a t i o n o f t h e m u s c o v i t e and t h e p a l y g o r s k i t e were produced. I n T o r r e j o n , t h e e s t a b l i s h m e n t o f t h e f l u v i a l network c r e a t e d t h e p r e s e n t morphology of t h e b a s i n w i t h t h e a l m o s t complete disappearance o f t h e n o r t h f l a n k , t h r o u g h w h i c h t h e T a j o now f l o w s .

F i g . 15 shows t h e f i v e phases o f

t h e e v o l u t i o n and s e d i m e n t a t i o n o f t h e m a t e r i a l s t h a t f i l l e d t h e T o r r e j o n basin.

The f e r r i t i z a t i o n and s m e c t i z a t i o n produced d u r i n g phase 4 a r e f a c u -

l t a t i v e and do n o t o c c u r i n a l l b a s i n s o f t h i s t y p e .

Phase 5 i s s p e c i f i c t o

the Torrejon basin.

3) B e n f i c a ( P o r t u g a l ) and San M a r t i n de Pusa Spain t y p e ( p a l y g o r s k i t e cement) P a l y g o r s k i t e appears as t h e p r i n c i p a l c l a y m i n e r a l i n t h e cement o f conglomerates and sandstones be1 i e v e d t o have been formed between t h e Upper Cretaceous and t h e Oligocene.

They appear i n t h e B e n f i c a Complex ( G a l o p i n de

Carvalho, 1968), i n t h e w e s t e r n s u b - b a s i n o f t h e T a j o b a s i n ( T a l a v e r a de l a Reina), t o t h e n o r t h o f t h e Mountains o f Toledo (San M a r t i n de Pusa, Puebla de Mantalban) (Ordonez e t a l . 1977a), and i n t h e e a s t e r n sub-basin. t o these a r e those d e s c r i b e d by Leguey e t

Similar

a l . (1983, t h i s p u b l i c a t i o n ) on

t h e s o u t h - e a s t b o r d e r o f t h e Duero b a s i n ( p r o v i n c e o f S e g o v i a ) . The cement i s made up o f p a l y g o r s k i t e t s m e c t i t e + c a l c i t e f dolomite

t

silica.

Ordonez e t a l .

(1977a) proposed a d i a g e n e t i c

o r i g i n f o r t h e p a l y g o r s k i t e by means o f t h e t r a n s f o r m a t i o n of i l l i t e through smectite.

Leguey e t a l .

(1983), on t h e o t h e r hand, i n

117 t e r p r e t t h e f o r m a t i o n o f t h e p a l y g o r s k i t e b y n e o f o r m a t i o n a t pH

8.5,

i n r e l a t i o n with the high porosity o f the rock,

of d o l o m i t e o r M g - c a l c i t e and s i l i c a ,

t h e presence

and a f t e r an orogenic a c t i -

vity. EXPLANATON

_ _ _ WATER

-FACE

R A ~ A

A

S

-

ILLlTlC CLAY

SAND AND PALVXftSKITE

ALTERATION ZONE SLATE

S

Fig.

15.-

P a l y g o r s k i t e f o r m a t i o n a t T o r r e j d n and e v o l u t i o n o f t h e b a s i n . ( F o r e x p l a n a t i o n , see t e x t )

T h i s d i a g e n e t i c p a l y g o r s k i t i z a t i o n c o i n c i d e s i n time w i t h an important "palygorskite event"

i n the e a r t h ' s sedimentary h i s t o r y

118 (Callen,

1 9 7 8 a n d 1 9 8 3 ) . T h i s was o f m a r i n e c h a r a c t e r ,

between t h e C r e t a c e o u s a n d t h e Eocene,

occurring

a n d was p r o b a b l y r e s t r i c t e d

t o t h e warm w a t e r s b e t w e e n 2 0 " a n d 40"N a n d S l a t i t u d e . T h e w a t e r s , b e i n g a d j a c e n t t o l i r n d rnbsses u n d e r g o i n g i n t e n s i v e w e a t h e i n g ,

pro-

v i d e d t h e s e a w i t h a s u i t a b l e g e o c h e m i c a l e n v i r o n m e n t f o r pa 1 y g o r s k i t e diagenesis.

A s i m i l a r o r i g i n can be i n f e r r e d here. ble,

o f varia-

Source areas,

b u t m a i n l y c a r b o n a t i c l i t h o l o g i e s , w e r e e r o d e d u n d e r semi - a r i d

o the

o r s e a s o n a b l y a r i d c o n d i t i o n s . Mg a n d S i w e r e b r o u g h t i n marginal

zones t o g e t h e r w i t h d e t r i t a l m a t e r i a l s .

The d i a g e n e t i c

f o r m a t i o n o f p a l y g o r s k i t e and s m e c t i t e s c o u l d have t a k e n p l a c e as Leguey e t a l .

(1983) i n d i c a t e .

4) L e b r i j a type (palygorskite-sepiol i t e marl s) S e d i m e n t a t i o n was p r o d u c e d i n a b r a c k i s h l a c u s t r i n e e n v i r o n ment o r p e r i m a r i n e . The s u r r o u n d i n g landmasses s l o w l y s u p p l i e d S i a n d Mg ( d o l e r i t e s ,

d o l o m i t i c r o c k s ) . On t h e o t h e r h a n d ,

dissolu-

t i o n s o f diatom c o l o n i e s ( e x t e r m i n a t e d b y an environmental

change

f r o m m a r i n e t o c o n t i n e n t a l ) a l s o c o u l d have i n t r o d u c e d s i l i c a t o t h e medium.

U n d e r t h e s e c o n d i t i o n s , w i t h t e c t o n i c s t a b i l i t y a n d an

a r i d climate,

s e p i o l i t e f o r m a t i o n was f a v o r e d a t a b o u t pH 8 .

Later, a f t e r s i g n i f i c a n t weathering o f t h e source area,

(be-

cause o f a s l i g h t subsidence o f t h e b a s i n and a m o i s t e r c l i m a t e ) g r e a t amounts o f magnesium,

iron, silica,

and d e t r i t a l m i n e r a l s ( q u a r t z , the basin.

Under t h e s e c o n d i t i o n s ,

than s e p i o l i t e .

etc.,

as i o n s o r g e l s ,

mica, c h l o r i t e ) were suppl i e d t o p a l y g o r s k i t e was f o r m e d r a t h e r

In a d d i t i o n , d e t r i t a l m i n e r a l s ( e s p e c i a l l y micas)

transformed t o p a l y g o r s k i t e i n the brackish environment,

as a r e -

s u l t o f an e q u i l i b r i u m between t h e u n s t a b l e p h y l l o s i l i c a t e s and t h e s o l u t i o n (Galan and F e r r e r o ,

I n the L e b r i j a deposite, and p a l y g o r s k i t e ,

1982).

t h e c l o s e r e l a t i o n s h i p between i l l i t e

as w e l l as t h e p o s s i b l e random i n t e r s t r a t i f i c a -

t i o n o f i l l i t e a n d p a l y g o r s k i t e i d e n t i f i e d , seem t o s u p p o r t t h e hypothesis o f the i l l i t e - p a l y g o r s k i t e

transformation.

The s m e c t i t e s i n t h e s e c l a y e y s e d i m e n t s c a n be d e t r i t a l o r c a n be formed by t r a n s f o r m a t i o n o f c h l o r i t e , by neoformation.

Occasionally,

i l l i t e or palygorskite,

or

c l i m a t i c o r t e c t o n i c changes p r o d u -

ced abundant d e t r i t a l m a t e r i a l s t h a t i n t e r f i n g e r i n t o t h e c l a y series. The a l t e r n a t i o n o f v a r l y a n d c l a y e y l a y e r s i n t h e s e r i e s c o u l d

119 p o s s i b l y h a v e been a r e s u l t o f p e r i o d i c c l i m a t i c c h a n g e s . Wet p e r i o d s f a v o r e d t h e f o r m a t i o n o f o a l y g o r s k i t e , and duri'ng d r i e r p e r i ods, e v a p o r i t i c s e d i m e n t a t i o n took p l a c e , w i t h l i t t l e s e p i o l i t e

or s m e c t i t e f o r m a t i o n . I n summary: The Spanish continental denosits of s e p i o l i t e and palygorskite can be grouped under four models whose principal f e a t u r e s a r e a s follows: Type 1: Tajo Basin Environment and f a c i e s

Deposits

a ) Detrital f a c i e s of

Vallecas-Vicilvaro Yunclillos Maga'n

d i s t a l zones o f alluvial-fans. Playa-1 ake b ) Marly f a c i e s of

1 acus t r i ne zones

c ) Evapori t i c f a c i e s (marly and/or gypsi ferous )

Principal Authigenic minerals (decreasing order)

SJ,

a, Sap,

Ca-Do, Ch,

Se, C h

Sap, S P

occurrences in Tajo S.1, basin( e.g .Esqui v i a s , Cerro de 10s Angeles, Pinto, e t c . )

pa.

C h , Ca

occurrences in Tajo Ca, Do, Y , Pa, S p basin(e.g .Tabladil l o ) ; Duero basin (e.g.Sacramenia); Ebro basin (e.g.Tarazona-Borja); Calatayud-Teruel basin; and Galician basins?

Type 2: TorrejBn Environment

Depos i t s

Tectonic basin on s l a t y basement. Palygorskite formation from a1 tered c h l o r i t e , and by a u t h i genesis

Torre j B n Coria La Ploraleja Cas telo-Branco Galician basins?

Principal transformed o r authigenic minerals (decreasing order)

pa, I , Cb

Sap, S o , Mo, Do, Ca,

120 Type 3: Benfica-San M a r t i n de Pusa Environment

Deposits

Principal authigenic minerals

Diagenetic formation (authigenesis ) i n d e t r i t a l sediments, i n s l i g h t l y a l k a l i n e pH f r o m Mg s o l u t i o n s . M a t e r i a l comes t o b a s i n a f t e r orogenic a c t i v i t y and p a l y g o r s k i t e forms under s e m i - a r i d o r seasonably a r i d c o n d i t i o n s

San M a r t i n de Pusa d e Pusa ( T o l e d o ) B e n f i c a Fm ( P o r t u g a l ) Valdegrados (Segovia)

Pa, Mg, Sm, Ca, Do, Ch

Environment

Depos it s

P r i n c i p a l transformed o r authigenic minerals

B r a c k i s h 1acus t r i n e e n v i ronmen t o f perimarine o r i g i n P a l y g o r s k i t e by transformation o r authigenesis

L e b r ij a Eastern basins (Almeria, Murcia)

Pa, Sp, Ch, Sm (Carbonates sometimes v e r y i m p o r t a n t )

Type 4: L e b r i j a

Minerals underlined correspond t o present ( o r p o t e n t i a l ) mine deposits C a = c a l c i t e ; Do=dolomite; Ch=chert; Y=gypsum; P a = p a l y g o r s k i t e ; Sap=saponite; Sp=sepiol it e ; S t v = s t e v e n s i t e ; I = i 11 it e ; Mo=montmori 11o n i t e ; C b = C r i s t o b a l it e

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125

SEPIOLITE IN THE AMBOSELI BASIN OF KENYA: A NEW INTERPRETATION

RICHARD L. HAY AND RONALD K. STOESSELL Department o f Geology and Geophysics, University o f C a l i f o r n i a , Berkeley, Cali f o r n i a 94720 (U.S.A.) and Department o f Earth Sciences, University o f New Orleans, New Orleans, Louisiana 70148 (U.S.A.)

ABSTRACT The Sinya Beds of Kenya (lower? P l e i s t o c e n e ) a r e s p r i n g - r e l a t e d d e p o s i t s o f t h e Amboseli Lake Basin.

They c o n t a i n both bedded waxy s e p i o l i t e and meer-

schaum, a massive l i g h t w e i g h t porous s e p i o l i t e .

The meerschaum d e p o s i t s a r e

l a r g e l y r e s t r i c t e d t o t h e c r e s t a l a r e a o f t h e Sinya Dome, which is about 760 x 215 m i n a r e a l e x t e n t .

-

Here t h e Sinya Beds c o n s i s t of 1.5

5 m o f dolomitic

c a l i c h e b r e c c i a , mostly i n t h e form o f dome- and mound- shaped masses, overl a i n by 1-3 m o f i n t e n s e l y folded and f r a c t u r e d waxy bedded s e p i o l i t e . Meerschaum occurs a s i r r e g u l a r pockets and small v e i n s , most o f which a r e i n t h e caliche breccias. The meerschaum-bearing p a r t o f t h e Sinya Beds o r i g i n a t e d a s follows. F i r s t , s e p i o l i t e and carbonate were p r e c i p i t a t e d along t h e s o u t h e a s t margin o f t h e l a k e b a s i n , which was f e d by s p r i n g s from Kilimanjaro.

This

s e p i o l i t e is o f

t h e bedded, waxy v a r i e t y . S l i g h t u p l i f t o f t h e Sinya Dome r a i s e d t h e c r e s t a l d e p o s i t s above t h e water t a b l e .

The c a l i c h e b r e c c i a s were formed within t h e

s e p i o l i t i c c l a y s by evaporation o f ground water i n t h e vadose zone.

Precipi-

t a t i o n o f carbonate was l o c a l i z e d over permeable zones ( f r a c t u r e s ? ) , r e s u l t i n g i n caliche-breccia

mounds and domes, t h e growth of which folded and f r a c t u r e d

t h e overlying clays.

Meerschaum was p r e c i p i t a t e d from ground water i n t h e

c a l i c h e b r e c c i a s and o v e r l y i n g c l a y s , very l i k e l y following a rise i n t h e water t a b l e . INTRODUCTION Scope and Purpose The o l d e s t P l e i s t o c e n e d e p o s i t s o f t h e Amboseli Basin c o n t a i n two v a r i e t i e s of s e p i o l i t e .

That o f economic importance is meerschaum,

lightweight form used f o r t h e manufacture o f high-quality

a massive, pure,

pipes.

More comnon

is a d e n s e r , waxy bedded s e p i o l i t e t h a t h a s not been u t i l i z e d economically. Dolomite is t h e h o s t rock f o r most of t h e meerschaum.

The Kenya d e p o s i t s have

been s t u d i e d by g e o l o g i s t s o f t h e Kenya Geological Survey (Williams, 1972) and by R.

K.

Stoessell (Stoessell,

1977; S t o e s s e l l and Hay,

1978). The s e n i o r

author v i s i t e d t h e s e d e p o s i t s only b r i e f l y i n 1975 with S t o e s s e l l .

Stoessell

discovered k e r o l i t e , a hydrated disordered v a r i e t y of t a l c , and proposed a geochemical and hydrologic e x p l a n a t i o n f o r t h e o r i g i n of t h e s e p i o l i t e ,

126

k e r o l i t e , and dolomite. New i n s i g h t on t h e o r i g i n of t h e Amboseli d e p o s i t s a r o s e i n t h e course o f s t u d i e s on Mg-silicate c l a y s and carbonates i n t h e Amargosa Desert of Nevada and C a l i f o r n i a (Hay e t a l . , 1980; Teague, 1981). The present paper is essent i a l l y a r e i n t e r p r e t a t i o n of t h e f i e l d d a t a already e s t a b l i s h e d by Williams (1972) and S t o e s s e l l and Hay (1978). Geologic S e t t i n g The Amboseli Basin is semiarid and covers an a r e a of about 400 km2 on t h e Kenya-Tanzania border. The western h a l f is dominated by a playa, Lake Amboseli, which bears water only during t h e r a i n y season. The basin (Fig. 1)

is bordered on t h e north by h i l l s of Precambrian metamorphic rock and on t h e south by M t . Kilimanjaro, which c o n s i s t s l a r g e l y of a l k a l i n e l a v a s , princip a l l y o l i v i n e b a s a l t s . M t . Kilimanjaro is a major source of water, which flows i n t o t h e basin a s streams and ground water.

'1'40'9

0

5

10

I S lam

Fig. 1. Map of t h e Amboseli Basin i n Kenya, a f t e r Williams (1972) and S t o e s s e l l (1977). Arrows i n d i c a t e r e g i o n a l flow p a t t e r n of s u r f a c e and subs u r f a c e water.

127

Lake sediments of P l ei s t o cen e Age comprise t h r e e s t r a t i g r a p h i c u n i t s (Willi a m s, 1972). The lowest is t h e Sinya Beds, which a r e exposed p r i n c i p a l l y on t h e c r e s t o f an a n t i c l i n e named t h e Sinya Dome, near t h e southern edge o f t h e basin. The maximum known t h i ck n es s of t h ese beds, pe ne tra te d by d r i l l i n g , is

18 m.

The Amboseli Clays unconformably o v e r l i e t h e Sinya Beds i n t h e v i c i n i t y A

of t h e Sinya Dome and u n d e r l i e t h e p r es ent l a k e ba sin a t shallow depth.

maximum t h i c k n e s s of about 60 m was estimated by Williams (1972). These a r e s e p i o l i t i c c l a y s with au t h i g en i c c a l c i t e , dolomite, g a y l u s s i t e , and Kfeldspar. I l J i t i c c l a y is widespread and may be d e t r i t a l , authigenic, or both. The 01 Tukai Beds a r e t h e youngest Ple istoc e ne u n i t . These comprised silts, c l a y s , c l ay - cl as t aggregates and c a l i c h e s . The formation is found i n t h e southern p a r t of t h e b as i n and h as a maximum thic kne ss of about 8 m. Authigenic m i n e r al s i n cl u d e s e p i o l i t e , analcime, o p a l , and calcite. THE SINYA BEDS The Sinya Beds a r e found i n both Kenya and Tanzania, but only t h e Kenya d e p o s i t s are considered i n t h i s paper. They are exposed p r i n c i p a l l y i n excav a t i o n s on t h e crest of t h e Sinya Dome, which is about 760 m long and 215 m 5 m of wide (Williams, 1972). Here t h e exposed beds c o n s i s t of about 1.5

-

nodular and b r ecci at ed dolomite, mostly i n t h e form o f e longa te mounds or domes, o v e r l a i n by 1-3 m o f s t a t i f i e d waxy s e p i o l i t e t h a t is inte nse ly folded and f r a c t u r e d . Dolomite b r ecci a c h a r a c t e r i s t i c a l l y forms t h e cores of a n t i c l i n e s (Fig. 2) and may occur a s i r r e g u l a r masses within deformed s e p i o l i t e . Dolomite masses a r e i n p l aces t h r u s t over crumpled beds o f s e p i o l i t e . The p a t t e r n of f o l d i n g is h i g h l y v a r i a b l e , but Williams (1972) noted some evidence t h a t minor f l e x u r e s r a d i a t e o u t from t h e core of t h e Sinya Dome. Meerschaum occurs a s i r r e g u l a r masses and small v e i n s , most comonly f i l l i n g t h e space between nodules and b l o ck s of dolomite. It forms l e n t i c l e s and v e i n s along f r a c t u r e s i n t h e waxy s e p i o l i t e . The meerschaum is ge ne ra lly undeformed, although Williams (1972) noted f r a c t u r e - f i l l i n g meerschaum with lin e a t e d s u r f a c e s s u g g es t i n g movement a f t e r de position. The amount o f meerschaum is small r e l a t i v e t o t h e dolomite and waxy s e p i o l i t e , and J. Walsh ( i n Williams, 1972) h as estimated 7.3 kg of meerschaum per c ubic m of host rock. Ke r o l i t e l o c a l l y o ccu r s around t h e s e p i o l i t e , s e p a r a t i n g it from t h e dolomite ( S t o e s s e l l and Hay, 1978). The waxy, bedded s e p i o l i t e is green or gre e nish gra y, l o c a l l y rootmarked, and c o n t a i n s t h i n v ei n s of dolomite and c a l c i t e .

The s e p i o l i t e is i n pla c e s

surrounded by t h i n s h e e t s o f waxy k e r o l i t e , which is p a l e grey t o p a s t e l green.

The c o n t act may be g r a d a t i o n a l over a d i s t a n c e o f 1 or 2 cm, and t h e

k e r o l i t e may w e l l be an a l t e r a t i o n product of t h e s e p i o l i t e ( S t o e s s e l l , 1977;

128

Fig. 2. Exposure of t h e Sinya Beds i n an excavation on t h e crest of t h e Sinya Dome. In cen t er o f photograph is a c a l i c h e bre c c ia dome forming t h e c o r e o f an a n t i c l i n e and flanked by i n t e n s e l y deformed c la ys. A t t o p a l a y e r o f rubble o v e r l i e s t h e Sinya Beds. T h i s exposure of t h e Sinya Beds is about 3 m high. S t o e s s e l l and Hay, 1978). The meerschaum, waxy green s e p i o l i t e , and k e r o l i t e a r e r e l a t i v e l y pure Mgs i l i c a t e c l a y s (Table 1 ) . Bulk samples of meerschaum have 0.2 t o 1.8 percent A1203 and 0.5 t o 1.0 percent FeO + Fe203 (Williams, 1972; S t o e s s e l l and Hay,

1978). A sample of waxy green s e p i o l i t e h as 1.8 percent Al2o3 atid 0.1 t o 0.7 percent FeO + Fe203. The amount of K20 ranges from 0.2 t o 1.0 percent and roughly c o r r e l a t e s with t h e amounts of aluminum and i r o n . This r e l a t i o n sugg e s t s t h e presence of a small amount o f c l a y mica, possibly phe ngitic i l l i t e . The d o l o m i t i c b r e c c i a s

consist

of

angular

blocks

and

irregular

to

subrounded nodules a s much a s 30 cm i n average diameter. Their s u r f a c e s commonly have a reticulate p a t t e r n of s u r f a c e c ra c ks, which may be f i l l e d by meerschaum ( S t o e s s e l l arld Hay, 1978). Adjacent blocks and nodules ge ne ra lly f i t t o g e t h e r , i n d i c a t i n g only s l i g h t displacement. Shearing is widespread and widely p a r a l l e l s t h e margins o f t h e b r e c c i a domes giving t h e appearance o f

129

TABLE 1. Chemical Composition of Sediments of the Sinya Bedsb s.d.a Si02 Ti02

0.09

A1203

0.04

Fe203 FeO

0.02

0.01

MnO

1

2

3

4

53.17

54.51

3.66

0.12 1.15

0.17 1.76

0.03 0.49

0.01 0.18

0.64 0.02

0.99 0.04

0.10

0.09

0.00

0.01

0.00

0.00

0.000

0.000 24.70

0.000 28.01

0.0005 20.11

0.23

0.52

31.48

0.85 0.26

0.06

53.70

NiO MgO CaO Na20

0.05 0.02

23.31 0.03

0.02

0.67

0.45

K20

0.03

0.61 0.02

0.97 0.04

0.03

0.06

9.83 9-76

8.29 8.79

7.97 7.18

44.78 0.38

99.86

99.61

99.95

100.83

2 '5 ' .H 0 '

2 H20-

+ C02

~~~

Total

0.01

~

a. Standard deviations were computed from duplicate analyses of major oxides on all samples. b. R. Stoessell did the analyses using a modified procedure of Shapiro and Brannock (1962). Totals of H20+ and C02 were computed using ignition loss with a correction for FeO. Sample 1 is fracture-filling massive white sepiolite (meerschaum); 2 , massive green sepiolite of the bedded clays; 3, gray kerolite; 4, dolomite. Samples 1 and 3 represent the purest specimens collected of sepiolite and kerolite, respectively. The computed formula for the white sepiolite (no. 11, based on 8 oxygens to balance all cations except H+, is (Mg 1,gONaO.07K0.04) (si2.94A10. 08Fe0.03) q . 5 ( O H ) .3.07H20* Similarly, the computed formula for the kerolite (no. 31, based on 11 oxygens, is 12K0.03Ca0-04) (Mg2. 9) (si3 .9 l M 0 .04Fe0. 01 'lo( OH) 2*2*62H20* Fe in the formulas refers to FeZ. anticlinal folding. Some of the blocks and nodules of dolomite contain rounded, sharp-margined masses of waxy sepiolite as much as a cm in diameter. The dolomite also contains finely disseminated Mg-silicate clay. The one sample studied in detail contains 10 percent of a trioctahedral smectite. This smectite is very likely stevensite (Mg smectite) in view of the very small amounts of A1 and Fe in the analyzed dolomite Table 1 , no. 4).

130 AS shown by d r i l l cores, t h e Sinya Beds on t h e f l a n k s and away from t h e dome c o n s i s t principall-y o f c l a y and mudstone, much o f which c o n t a i n s car-

bonate (dolomite?), and a t l e a s t some o f which is s e p i o l i t i c (Williams, 1972). Meerschaum was found i n a s i n g l e d r i l l hole away from t h e crest of t h e dome. The dolomitic b r e c c i a s a r e apparently r e s t r i c t e d t o t h e c r e s t of t h e dome. GEOCHEMISTRY A t temperatures and pressures corresponding t o near earth-surface condit i o n s , t h e i n i t i a l formation of magnesium s i l i c a t e s is determined by r e a c t i o n k i n e t i c s r a t h e r than chemical s t a b i l i t i e s . Preliminary s t a b i l i t y r e l a t i o n s between Amboseli c r y p t o c r y s t a l l i n e s e p i o l i t e and k e r o l i t e were reported by S t o e s s e l l (1977) from 25OC and 1 bar. These hydrolysis experiments l a s t e d 13 months for s e p i o l i t e and 6 months f o r k e r o l i t e . For each mineral, experiments were run i n 5 s o l u t i o n s with s t a r t i n g compositions ranging from a c i d i c t o basic. The r e s u l t s implied e q u i l i b r a t i o n with k e r o l i t e i n s o l u t i o n s having a f i n a l pH less than 8 and e q u i l i b r a t i o n with s e p i o l i t e i n more b a s i c s o l u t i o n s . The thermodynamic l o g K values for s e p i o l i t e (Mg2Si34.5(0H).3H20) and kerol-

i t e (Mg3Si4Olo(0H),.nH20) were 15.50 2 0.21 and 23.54 f o r t h e following r e x t i o n s :

0.19,

respectively,

s e p i o l i t e + 4H+ = 2Mg2+ + 3Si02 + 5.5H20 k e r o l i t e + 6H+ =

3N2++

4Si02 + (4tn)H20

The value f o r s e p i o l i t e is thermodynamically c o n s i s t e n t with t h e 1 bar solub i l i t y data a t 51' and 90°C reported by C h r i s t , H o s t e t l e r , and S i e b e r t (1973).

W e know of no o t h e r experimental d a t a for k e r o l i t e . These r e s u l t s a r e t e n t a t i v e , and f i n a l experimental d a t a (8 year e q u i l i b r a t i o n s ) w i l l be reported later by t h e j u n i o r author. The K values imply s e p i o l i t e i s metastable with r e s p e c t t o k e r o l i t e , and both a r e metastable with r e s p e c t t o talc. S e p i o l i t e is s t a b l e with regard t o s e r p e n t i n e a t aqueous s i l i c a a c t i v i t i e s g r e a t e r than quartz s a t u r a t i o n . Only a t very high s i l i c a a c t i v i t i e s ( g r e a t e r than amorphous s i l i c a s a t u r a t i o n ) does s e p i o l i t e become more s t a b l e than k e r o l i t e and talc. The r a t h e r c o m n low temperature formation of s e p i o l i t e must then be due t o k i n e t i c i n h i b i t i o n s i n t h e formation of o t h e r magnesium silicates. Water chemistry d a t a f o r 23 samples taken within Amboseli Basin were reported by Stoessell and Hay (1978). The water samples range i n s o l u t e s from 60 t o 7,000 p a r t s p e r million (ppm). These data show a general i n c r e a s e i n 2 a 2+/(a and a ~ i 0 2in water moving towards t h e l a k e bed. Mg H+

Two p a r a l l e l

131

trends were observed, one for s u r f a c e water and one for ground water. Twelve of t h e samples were supersaturated with respect t o both s e p i o l i t e and keroli t e . S i g n i f i c a n t formation o f Mg s i l i c a t e s appeared t o occur a t pH values g r e a t e r than 7.9 a s shown by r e v e r s a l s i n a c t i v i t y trends. This supports t h e experimental observatioh by S i f f e r t (1962) t h a t a pH of a t l e a s t 8 is necessary t o nucleate s e p i o l i t e . Field r e l a t i o n s a t Amboseli imply k e r o l i t e formed l a t e r than waxy s e p i o l i t e and sometimes a s a s e p i o l i t e a l t e r a t i o n product. The present-day ground water compositions i n t h e Sinya Beds have high concentrations of Mg ( > 10 ppm) and

sio2

60 ppm), pH between 7.9 and 8.3, and t o t a l dissolved s o l i d contents below 1000 ppm. The experimental d a t a of Stoessel (1977) a r e c o n s i s t e n t with k e r o l i t e nucleation below a pH of 8. For these reasons, we would hypothesize k e r o l i t e forming in, contact with s l i g h t l y basic waters of low s a l i n i t y . These waters contain Mg and Si02 derived from leaching t h e o l i v i n e b a s a l t s of M t . (>

Kilimanjaro. The l a c k of A 1 i n d e t r i t a l m a t e r i a l within t h e predominantly carbonate Sinya Beds prevents t h e formation of saponites or palygorskite, r e s u l t i n g i n r e l a t i v e l y pure magnesium s i l i c a t e s . W e want t o emphasize t h a t t h e formation of Mg s i l i c a t e s a t Amboseli is a problem of r e a c t i o n k i n e t i c s , not chemical s t a b i l i t y . Waters i n t h e basin become supersaturated a s a r e s u l t of normal weathering processes. Because k e r o l i t e is more s t a b l e than s e p i o l i t e , i n c r e a s e s i n ang2+, aSiO2, and pH w i l l increase t h e thermodynamic p o t e n t i a l t o transform s e p i o l i t e i n t o k e r o l i t e . However, thermodynamics tell us only t h e r e a c t i o n d i r e c t i o n , not t h e r e a c t i o n kinetics. W e do know t h a t t o p r e c i p i t a t e k e r o l i t e d i r e c t l y r e q u i r e s very high supersaturation (Jones, 1982). This is probably not t h e case f o r transformat i o n from a precursor such a s s e p i o l i t e or s t e v e n s i t e .

The nature of t h e pre-

cursor w i l l have an important effect on t h e r e a c t i o n k i n e t i c s . The k i n e t i c importance of pH i n t h e formation of Mg s i l i c a t e s is not y e t understood. The effect of pH on k e r o l i t e formation may have t o do with t h e k i n e t i c s of transformation of t h e precursor. I n t h e hydrolysis experiments of S t o e s s e l l (19771, t h e r e a c t i o n k i n e t i c s decreased s i g n i f i c a n t l y with increases i n pH. Our conclusion t h a t a high pH is n o t necessary t o form s i g n i f i c a n t amounts of k e r o l i t e is based on preliminary experimental results, t h e p r e s e n t d a y ground water chemistry within t h e Sinya Beds, and t h e assunption t h a t k e r o l i t e is p r e s e n t l y forming i n t h e s e beds.

Other researchers might

disagree. Khoury, Eberl, and Jones (1982) b e l i e v e k e r o l i t e formed i n t h e Amargosa Desert d e p o s i t s i n waters of higher pH and s a l i n i t y than those presently found i n t h e Sinya Beds a t Amboseli. Those conclusions a r e based on the experimental observation by S i f f e r t ( 1962) that t a l c can be p r e c i p i t a t e d with a t r i o c t a h e d r a l smectite a t a pH above 9 , together with an observed

132

a ss o c i a t i o n of small amounts o f h a l i t e with k e r o l i t e and s t e v e n s i t e i n t h e Amargosa Desert deposits, Jones 1982) p o i n t s out t h a t k e r o l i t e i s o f t e n t h e

result o f a r e a ct i o n between Mg i n t e r l a y e r s in a p r e e x i s t i n g smectite with aqueous Si02. K er o l i t e i n t h e margosa Desert d e p o s i t s is i n t e r s t r a t i f i e d with s t e v e n s i t e and may r ep r es en t an a l t e r a t i o n of a p r e e x i s t i n g s m e c t i t e ; whereas, a t Amboseli, k e r o l i t e appears t o have o f t e n had a s e p i o l i t e precurs o r . These d i f f e r e n c e s i n p r ecu r s o r s should n e c e s s i t a t e d i f f e r e n t s o l u t i o n compositions t o overcome d i f f e r e n t k i n e t i c c o n t r a i n t s . O R I G I N OF SINYA BEDS

Previous i n t e r p r e t a t i o n The o r i g i n o f t h e Sinya Beds i s i n f er r ed by S t o e s s e l l and Hay (1978) a s f 01lows

.

1.

S e p i o l i t e was p r e c i p i t a t e d along t h e southe rn, spring-fed margin of t h e

lake.

Water l e v e l f l u c t u a t e d , and a t times of low level t h e s e p i o l i t e dehy-

d r a t e d , producing d e s i c c a t i o n cr ack s , and developing a b r e c c i a t e d , nodular texture. 2.

The waxy bedded s e p i o l i t e which now o v e r l i e s t h e dolomite was pre c ipi-

t a t e d i n t h e l a k e following a rise i n l e v e l .

3.

The lower, f r act u r ed s e p i o l i t e was dolomitized during a drop i n l a k e l e v e l . I t was suggested t h a t t h i s ground water was low i n s i l i c a and derived from recharge a r e a s i n Precambrian carbonate

rocks t o t h e north.

The Mg and

Si02 r e l e a se d i n t o s o l u t i o n by d o l o mi t i zat i on were p r e c i p i t a t e d a s s e p i o l i t e in open s p a c e s around t h e carbonate blocks. The small, rounded masses of waxy s e p i o l i t e i n some o f t h e dolomite were considered unreplaced relicts o f t h e primary s e p i o l i t e . The s h ar p co n t act between t h e dolomite and ove rlying bedded s e p i o l i t e was believed t o r ep r es en t t h e water t a b l e a t t h e time of dolomitization. 4.

Doming and i n t e n s e , smaller-scale deformation were a t t r i b u t e d t o t e c -

t o n i c a c t i v i t y following d ep o s i t i o n o f t h e Sinya Beds.

5.

Kerolite was formed from s e p i o l i t e by a lowering o f pH, e s s e n t i a l l y a s a weathering product. Revised I n t e r p r e t a t i o n T h i s new i n t e r p r e t a t i o n

o f t h e meerschaum-bearing p a r t o f t h e Sinya Beds

d i f f e r s from t h e e a r l i e r one i n t h e o r i g i n of t h e dolomitic bre c c ia and meers c h a m , m d i n t h e cause and timing o f t h e i n t e n s e f o l d i n g of t h e c l a y s above t h e dolomitic b r ecci as .

The i n t e r p r e t a t i o n is a s follows.

133

1.

S e p i o l i t e and carbonate (dolomite?) were p r e c i p i t a t e d along t h e south-

e r n , spring-fed margin o f t h e l ak e.

Th i s s e p i o l i t e inc lude s t h e waxy s e p i o l -

i t e forming t h e upper p a r t o f t h e Sinya Beds. 2. S l i g h t doming r a i s e d t h e c r e s t a l d e p o s i t s of t h e Sinya Dome above t h e water t a b l e . Ground water from Kilimanjaro seeped upward through permeable zones, probably f r a c t u r e s , i n t h e c r e s t a l area. Nodules of carbonate with disseminated s t e v e n s i t e were formed i n evaporation of ground water a t o r above th e water t a b l e and within t h e p r e- ex i s t i n g s e p i o l i t e c l a y s (Fig. 3).

Contin-

ued evaporation r e s u l t e d i n t h e growth o f new nodules below those already formed, pushing them upward and deforming t h e ove rlying c l a y s .

Fra c ture s i n

t h e deformed c l a y s would have aided evaporation and l o c a l i z e d nodule growth, u l t i m a t e l y r e s u l t i n g i n t h e dome-shaped masses of c a l i c h e b r e c c i a t h a t form c o r e s of a n t i c l i n e s . Mann and Horwitz (1979) have c a l l e d upon t h i s mechanism f o r t h e growth of steep-sided c a l c r e t e ( = c a l i c h e ) domes i n western A ustra lia . These domes, l i k e some of t h e Amboseli domes, have s t r u c t u r e s engendered by shear and c o n c en t r i c f o l d i n g due t o upward growth pre ssure .

Inte nse , upward

small-scale deformation of t h e bedded c l a y s is a t t r i b u t e d t o growth of t h e domes and i r r e g u l a r masses of c a l i c h e b r ecc ia . The small rounded masses of waxy s e p i o l i t e i n some o f t h e dolomite nodules and bloc ks a r e considered c l a s t s of matrix c l a y incorporated d u r i n g growth of t h e carbonate. A s y e t unresolved is whether t h e c a l i c h e b r e c c i a s were formed d i r e c t l y a s dolomite or by dolomitization of calcium carbonate.

3.

Meerschaum f i l l i n g space between dolomite bloc ks and f r a c t u r e s in

folded c l a y s was deposited a f t e r growth of t h e a dja c e nt blocks and f o l d i n g of the clays.

Indeed, most or n e a r l y a l l of t h e meerschaum may have been depo-

s i t e d a f t e r growth and u p l i f t o f t h e c a l i c h e b r e c c i a s and deformation of t h e clays.

The change i n

p r e c i p i t a t i o n from carbonate

(plus stevensite)

to

s e p i o l i t e may have been caused by a rise i n t h e water t a b l e , with t h e meerschaum deposited from ground water less evaporated t h a t t h e vadose water f r o m which t h e c a l i c h e b r e c c i a s were p r e c i p i t a t e d . Some, a t l e a s t , o f t h e meerschaum was probably deposited b ef o r e growth of t h e c a l i c h e b r e c c i a s had been completed, i n view o f t h e l i n e a t e d ( s l i ck en side d? ) f r a c t u r e - f i l l i n g meerschaum noted by Williams. Meerschaum could have been deposited during growth of t h e c a l i c h e b r e c c i a s a s a r e s u l t of a s l i g h t , temporary rise i n t h e water t a b l e , followed by a lowering d u r i n g which more c a l i c h e bre c c ia was formed. 4. Doming continued following d ep o s i t i o n of t h e Sinya Beds, and they were eroded i n t h e a r e a p r i o r t o d ep o s i t i o n of t h e Amboseli c l a y s . s e p i o l i t e i n t h e lower p a r t o f

Seams of white

t h e Amboseli c l a y s i n t h e c r e s t a l a r e a

( S t o e ss e l and Hay, 1978) were probably p r e c i p i t a t e d from ground water seeping along f r a c t u r e s , s i m i l a r t o p r e c i p i t a t i o n of meerschaum i n t h e Sinya Beds.

134

W

a

I.-I

lake levelL ~-

-_sepiolite &

1 c I _ _ _

carbonates

,water

groundwater

E

It

20m

table

discharge

Fig. 3. Schematic east-west cross-section showing t h e development o f t h e Sinya Dome and c a l i c h e b r ecci a masses i n t h e Sinya Beds. Se c tion ( a ) shows t h e Sinya Beds p r i o r t o folding. Section ( b ) r e p r e s e n t s t h e e a r l y s t a g e s of doming, and Section (c) is of t h e dome a f t e r f o l d i n g and shows c a l i c h e b r e c c i a mounds, which were formed a t or above t h e water t a b l e following and possibly during doming. Bedded s e p i o l i t e and carbonates above t h e bre c c ia mounds were deformed by t h e i r growth. COMPARISON WITH AMARGOSA DEPOSITS

Deformation of beds by growth of c a l i c h e (= c a l c r e t e ) from below have been reported by Price (1925), Jennings and Sweeting (19611, and Reeves (1976, p. 60-64). Reeves (1976, Fig. 3-14) and Horwitz and Mann ( 1979) f i g u r e c a lic he b r e c c i a domes g e n er al l y s i m i l a r i n t e x t u r e and s t r u c t u r e t o those of t h e Sinya These domes a r e , however, smaller than those of t h e Sinya Beds, and a s s o c i a t e d Mg-silicate c l a y s were not reported.

Beds.

Some o f t h e Pliocene and lower? P l ei s t o cene d e p o s i t s i n t h e Amargosa Desert o f southwestern Nevada and s o u t h eas t er n C a l i f o r n i a a r e s t r i k i n g l y s i m i l a r i n

most r e s p e c t s t o t h e Sinya Beds on the crest of t h e Sinya Dome. The Amargosa Desert was a l a k e b as i n i n t h e Pliocene and probably e a r l y Pleistocene. Springs supplied l a r g e a m u n t s of water t o t h e ba sin, r e s u l t i n g i n l a r g e quant i t i e s o f carbonates and Mg-silicate c l a y s - p r i n c i p a l l y s e p i o l i t e and stevens i t e with i n t e r l a y e r e d k e r o l i t e (Khoury, 1978). Most of t h e c l a y s were

135

deposited i n playa and marshland environments. Caliche-breccia masses comparable i n s i z e t o those of t h e Sinya Beds. are widespread a t two p l aces i n t h e d e s e r t (Teague, 1981). I n t h e e a ste rn p a r t they form a narrow zone about 1 km long t h a t appears t o be loc a liz e d along a p r e - e x i st i n g f a u l t . Near t h e southwestern margin the y unde rlie most o f an a r e a about 3 h long and 600 m wide. A s seen i n cross-section, t h e sm a lle r, better-exposed c a l i c h e b r ecci a masses form domes and mounds 2-3 m high and 4-6

m wide.

The o v er l y i n g and ad j acen t c l a y s a r e deformed, comnonly i n t o a n t i -

c l i n e s w i t h c a l i c h e b r e c c i a co r es . Some of t h e c a l i c h e b r e c c i a s form piercement s t r u c t u r e s .

The l a r g e s t masses, only incompletely exposed in excava-

t i o n s , have eroded t o p s and a r e a t l e a s t 7 m t h i c k . l a r g e r masses and some o f t h e s mal l er ones.

Shearing is comnon in t h e

The b r e c c i a s c o n s i s t of angular fragments and nodules many of which have r e t i c u l a t e s u r f a c e c r a c k s a s i n dolomite o f t h e Sinya Beds. The carbonate i n t h e Amargosa b r ecci a can be dolomite, c a l c i t e o r both. suggest t h a t t h e dolomite has replaced c a l c i t e .

Field relationships

The carbonate rocks contain

an average about 10 p er cen t o f disseminated Mg-silicate c l a y , p r i n c i p a l l y kerolite-stevensite. I n t e r s t i t i a l c l a y is p r i n c i p a l l y ke rolite -ste ve nsite b u t can be s e p i o l i t e .

With few exceptions t h e i n t e r s t i t i a l c l a y is deformed i n

folded and sheared zones, showing that most o f it had been deposited before growth and displacement of t h e c a l i c h e b r e c c i a s had been completed. The Amargosa and Amboseli c a l i c h e b r e c c i a s d i f f e r p r i n c i p a l l y i n t h e amount and mineral composition of t h e i n t e r s t i t i a l Mg-silicate c la y. This may l a r g e l y r e f l e c t a d i f f e r e n c e i n t h e water composition, with t h a t of t h e Amargosa d e p o s i t s derived l a r g e l y from recharge a r e a s in carbonate rocks whereas that of Amboseli is from v o l can i c rocks.

Hydrologic and c l i m a t i c d i f f e r e n c e s

may have been a d d i t i o n a l f a c t o r s , which cannot pre se ntly be evaluated. ACKNOWLEDGEMENTS The work o f Williams (1972) and S t o e s s e l l (1977) provided most of t h e f a c t s upon which t h i s a n a l y s i s was made. F i n an ci a l support for t h e Amboseli f i e l d work was and provided by National Science Foundation Grant DES 72-021523 and DES 74-12782.

Work i n t h e Amargosa Desert was supported by National Science

W e a r e indebted t o t h e Republic of Kenya f o r permission t o study t h e Amboseli d e p o s i t s and t o I n d u s t r i a l Minerals Ventures, Inc., and t o Jack Mayhew, t h e i r g e o l o g i s t , f o r t h e opportunity t o study t h e Foundation Grant EAR 78-01776.

Amargosa d e p o s i t s .

136 REFERENCES C h r i s t , C. L., Hostetler, P. B., and S i e b e r t , R. M. (1973) Studie s i n t h e s y s t e m Mg0-Si02-C02-H 0 111: The act i v i t y-produc t c onsta nt o f s e p i o l i t e . Am. J. S c i . , 273: 65-83. Hay, R. L., Wiggins, B., and Teague, T. T. '(1980) Spring-related c a rbona te s and Mg-silicate c l a y s i n t h e Amargosa Basin o f Nevada and C a l i f o r n i a ( a b s . ) . Geol. Soc. Am. Ab s t r act s with Programs 12: 443-444. Jennings, J. W., and Sweeting, M. M. (1961) Caliche pseudo-anticlines i n t h e F i t z r o y Basin, western Au s t r al i a. Am. J . Sci., 259: 635-9. Jones, B. F. (1982) Clay mineral d i ag en es is i n l a c u s t r i n e sediments. U.S. Geological Survey Prof. Paper ( i n p r e s s ) . Khoury, H. N. (1978) Mineralogy and chemistry of some unusual c l a y d e p o s i t s i n t h e Amargosa Desert, southern Nevada. Unpublished Ph.D. t h e s i s , Univers i t y of I l l i n o i s , Urbana, 171 pp. Khoury, H. M., E b e r l , D. D., and Jones, B. F. (1982) Origin of magnesium c l a y s from t h e Amargosa Desert, Nevada. Clays and Clay Minerals, 30: 327-336. Mann, A. W., and Horwitz, R. C. (1979) Groundwater c a l c r e t e d e p o s i t s i n Aust r a l i a . J. G e o l . Soc. Aust., 26: 293-303. Price, A. W. (1925) Caliche and pseudo-anticlines. Bull. Am. Assoc. Pe trol. G e o l . , 9: 1009-1017. Reeves, C. C. (1976) Caliche; o r i g i n , c l a s s i f i c a t i o n , morphology, and uses. Estacado Books, Lubbock, Texas, 233 pp. S i f f e r t , B. (1962) Some r e a c t i o n s o f s i l i c a i n s o l u t i o n : formation of c l a y . Reports G e o l . Map S er v i ce Alsace-Lorraine, 21: 100 pp. S t o e s s e l , R . K. (1977) Geochemical s t u d i e s of two magnesium s i l i c a t e s , s e p i o l ite and k e r o l i t e . Ph.D. Th es i s , University of C a l i f o r n i a , Berkeley, CA, 122 pp. S t o e s s e l , R . K., and Hay, R. L. (1978) The geochemical o r i g i n of s e p i o l i t e and k e r o l i t e a t Amboseli, Kenya. Contrib. Miner. Pe trol., 65: 255-267. Teague, T. T. (1981) Authigenic s i l i c a t e s and carbonates i n playa and r e l a t e d d e p o s i t s from t h e Amargosa Desert, Nevada. M.S. Thesis, University of C a l i f o r n i a , Berkeley, CA, 78 pp. W i l l i a m s , L. A . J . (1972) Geology o f t h e Amboseli area. Geol. Surv. Kenya, 90: 86 pp.

137

SEPIOLITE I N PLEISTOCENE LAKE TECOPA, I N Y O COUNTY, CALIFORNIA HARRY C. STARKEY AND PAUL D. BLACKMON U.S. GEOLOGICAL SURVEY, DENVER, COLORADO, U.S.A.

A b s t r a c t - - P l e i s t o c e n e Lake Tecbpa, i n s o u t h e a s t e r n I n y o County, C a l i f o r n i a , was formed i n a c l o s e d b a s i n when t h e Amargosa R i v e r was b l o c k e d a t t h e s o u t h e r n end o f t h e v a l l e y .

The l a k e - b o t t o m sediments c o n s i s t o f mudstones i n t e r b e d d e d

w i t h t u f f s formed from i n t e r m i t t e n t v o l c a n i c ash f a l l s . S e p i o l i t e i s found n e a r t h e m a r g i n s of t h e l a k e b a s i n , s t r a t i g r a p h i c a l l y w i t h i n about 2 m e t e r s o f t h e uppermost t u f f s .

The s e p i o l i t e was p r o b a b l y

p r e c i p i t a t e d when s i l i c a t a k e n i n t o s o l u t i o n f r o m t h e v o l c a n i c ash became a v a i l a b l e t o t h e magnesium-bearing,

high-pH (9.0)

l a k e waters.

Z e o l i t e s were

formed w i t h i n t h e ash beds and t h e s e p i o l i t e s were formed o u t s i d e t h e ash beds.

A p p a r e n t l y s e p i o l i t e was n o t produced w i t h i n t h e ash beds because o f t h e

presence o f r e a c t i v e a1 umina. INTRODUCTION S e p i o l i t e was r e c o g n i z e d by Sheppard and Gude (1968) i n t h e f i n e r - t h a n - 2 - u m f r a c t i o n o f some mudstones i n P l e i s t o c e n e Lake Tecopa.

They presumed i t t o be

a u t h i g e n i c and t h e o t h e r c l a y s t o be d e t r i t a l , and t h e y suggested f u r t h e r sampling t o d e f i n e t h e d i s t r i b u t i o n o f t h e s e p i o l i t e and i t s r e l a t i o n t o t h e other c l a y minerals. O f 158 samples c o l l e c t e d by t h e p r e s e n t a u t h o r s f o r c l a y s t u d i e s o f t h e Lake

Tecopa beds, o n l y 43 c o n t a i n e d s e p i o l i t e .

Only t h o s e samples t h a t c o n t a i n e d

s e p i o l i t e , regardless o f q u a n t i t y , are included i n t h i s report.

Results o f t h e

s t u d i e s o f a l l t h e samples c o l l e c t e d have been p u b l i s h e d elsewhere ( S t a r k e y and B1 ackmon, 1979). P l e i s t o c e n e Lake Tecopa, about 23 km l o n g and 18 km wide, i s l o c a t e d i n t h e W a v e D e s e r t about 32 km e a s t o f Death V a l l e y N a t i o n a l Monument i n southeastern I n y o County, C a l i f o r n i a , w i t h i n Tps. 20, 21, and 22 N and Rs. 6 and 7 E.

Las Vegas, Nevada, t h e n e a r e s t l a r g e c i t y , i s a b o u t 97 km t o t h e e a s t

(Fig. 1). GEOLOGY OF THE BASIN The Amargosa R i v e r , t h e c h i e f s u r f a c e d r a i n a g e o f t h e area, o r i g i n a t e s i n Pahute Mesa, a b o u t 175 km n o r t h w e s t o f Las Vegas, Nev.

I n t h e area under s t u d y

t h e r i v e r i s d r y e x c e p t w h e r e , w a t e r i s s u p p l i e d by s p r i n g s n e a r Tecopa and

138 117O

116O

115O

36

-

0 35

0 Baker

50 Km

Fig. 1. Index map showing l o c a t i o n o f Lake Tecopa. Shoshone, C a l i f o r n i a , and by i n f r e q u e n t heavy r a i n s .

During Pleistocene time

t h e r i v e r was b l o c k e d s o u t h o f t h e p r e s e n t town o f Tecopa, and t h e muds and v o l c a n i c ashes were d e p o s i t e d i n t h e r e s u l t i n g l a k e water.

E v e n t u a l l y , as t h e

sediments f i l l e d t h e b a s i n t h e w a t e r o v e r f l o w e d , c u t t i n g t h r o u g h t h e b a r r i e r and d r a i n i n g t h e l a k e . The mudstones and t u f f s have a s l i g h t b u t d e f i n i t e d i p toward t h e c e n t e r o f t h e b a s i n which p r o b a b l y was produced by t h e o r i g i n a l s l o p e o f t h e b a s i n and by p o s t d e p o s i t i o n a l compaction.

They a r e d i s s e c t e d by s t e e p s i d e d washes, which

make t r a v e r s e d i f f i c u l t b u t p r o v i d e e x c e l l e n t exposures o f t h e beds f o r study, a l t h o u g h t h e l o w e s t beds a r e n o t exposed. The t u f f s t h a t a r e a s s o c i a t e d w i t h t h e s e p i o l i t e d e p o s i t s range i n t h i c k n e s s f r o m s e v e r a l c e n t i m e t e r s t o about 4 m ( F i g . 2).

Three o f t h e t h i c k e r t u f f s

were l a b e l e d A, B, and C i n descending o r d e r by Sheppard and Gude (1968). t u f f s m a i n l y c o n s i s t o f z e o l i t e s , g l a s s , m o n t m o r i l l o n i t e , and i l l i t e .

The

The

z e o l i t e s p r e s e n t a r e p h i l l i p s i t e , c l i n o p t i l o l i t e , and a few m i n o r occurrences o f e r i o n i t e and c h a b a z i t e .

I t appears p o s s i b l e t h a t a t h i n ash bed may have

e x i s t e d about 7.6 t o 9.1 m above t u f f A, b u t we found n o t r a c e o f it.

However,

139

I

---A

.... . .. ...... ....... ,.::.: :,.. .,.;.

Sandstone

xxxxxx

3

Tuff

Tuff

2 20

METERS

A:::L-

xxxxxxxx

---x x x x x x

Fig. 2. G e n e r a l i z e d s t r a t i g r a p h i c s e c t i o n o f P l e i s t o c e n e Lake Tecopa d e p o s i t s showing s t r a t i g r a p h i c l o c a t i o n o f s e p i o l i t e - b e a r i n g samples ( m o d i f i e d f r o m Sheppard and Gude, 1968). Numerals i n d i c a t e t h e number o f samples t a k e n a t a given s t r a t i g r a p h i c l e v e l .

140

o t h e r n o n s e p i o l i t e - b e a r i n g samples c o l l e c t e d a t t h a t e l e v a t i o n d i d c o n t a i n c l i n o p t i l o l i t e and m o n t m o r i l l o n i t e , b o t h p r o d u c t s o f a s h d e v i t r i f i c a t i o n t h a t d o n o t n o r m a l l y o c c u r i n t h e mudstones o f Lake Tecopa. DESCRIPTION OF THE SEPIOLITE E l e c t r o n m i c r o g r a p h s show t h a t most o f t h e s e p i o l i t e f i b e r s a r e l e s s t h a n

1 wn l o n g , a l t h o u g h one sample d i d c o n t a i n f i b e r s more t h a n 2 um l o n g . T r a n s m i s s i o n e l e c t r o n m i c r o g r a p h s o f s u r f a c e r e p l i c a s , and s c a n n i n g e l e c t r o n m i c r o g r a p h s show t h a t a t l e a s t some o f t h e s e p i o l i t e f i b e r s o c c u r i n s m a l l , randomly o r i e n t e d bundles. The s e p i o l i t e i s , i n a l l samples, a d m i x e d w i t h o t h e r m i n e r a l s , t h e l a r g e s t amount b e i n g a b o u t 50%.

An a t t e m p t t o p u r i f y t h e s e p i o l i t e i n one sample b y

p h y s i c a l means was n o t s u c c e s s f u l . fraction,

The p u r e s t f r a c t i o n ,

t h e less-than-O.2-um

c o n t a i n e d s e p i o l i t e , s a p o n i t e , i l l i t e , and p o s s i b l y p o t a s s i u m T h i s f r a c t i o n was t r e a t e d w i t h a 1:3 a c e t i c a c i d : w a t e r s o l u t i o n f o r

feldspar.

t e n d a y s t o d e s t r o y t h e s a p o n i t e (MacEwan and W i l s o n , 1980; S t a r k e y and o t h e r s , The r e s u l t i n g sample appeared, b y X - r a y powder d i f f r a c t i o n , t o b e

1977).

s e p i o l i t e c o n t a i n i n g some i l l i t e and p o s s i b l y K - f e l d s p a r .

I

I

I

The X-ray powder

I

I - - I llite impurities may contribute to the intensities of these peaks

P--Potash feldspar impurities may contribute to the intensities of these peaks

60

DEGREES F i g . 3. X-ray d i f f r a c t i o n p a t t e r n (CuKa r a d i a t i o n , 40Kv, 30mA) o f t h e l e s s than-0.2-wn f r a c t i o n a f t e r t r e a t m e n t f o r t e n d a y s w i t h a s o l u t i o n o f 1:3 a c e t i c a c i d : w a t e r , compared w i t h a p a t t e r n o f a s e p i o l i t e sample f r o m E s k i C h e h i r , Turkey

.

141 d i f f r a c t i o n d a t a , w i t h t h e i l l i t e and f e l d s p a r r e f l e c t i o n s d e l e t e d , a r e compared i n T a b l e 1 w i t h p r e v i o u s l y p u b l i s h e d d a t a . The c o a l e s c i n g o f peaks and t h e b r o a d c h a r a c t e r i s t i c s o f most o f t h e peaks can be seen i n F i g p r e 3. TABLE 1 Comparison o f X - r a y powder d i f f r a c t i o n d a t a f o r s e p i o l i t e f r o m P l e i s t o c e n e Lake Tecopa w i t h t h o s e f r o m t w o p r e v i o u s l y r e p o r t e d o c c u r r e n c e s . [ B r a c k e t s i n d i c a t e peaks w h i c h c o a l e s c e . B, b r o a d ; NR, n o t r e s o l v e d ; _ _ _ _ _ , n o t found o r n o t reported] Lake Tecopa, Calif. d

d

I

12.3 7.5 6.6 5.0 4.49 4.25

ion

-_---

Eski Chehir Asia Minor1

4 6 7 33 15

Kenya

I

12.3 7.6

_____ 4.9 4.5 4.3

-----

_----

__--_

11 9 26 22 6

3.746 3.49 3.34

208 5

3.76 3.45 3.32 3.23 3.00

1

12.1 7.7 6.7 5.0 4.47 4.31

100 5B 5B 5B 18 25

4.17 3.738

---_-

20NR ,B 2.98

_____ 2.67 2.56

d

(40NR,B)

3.339 3.187 3.048 2.79? 2.675 2.59 2.56

5 20

----35 12 5 4 8NR 40NR

2.49 2.421

17B

2.26 2.12 2.06

11B 7B 4B

2.01 1.97 1.924 1.720 1.668

4 4 4 6 78

1.589

_--_-

68

-----

1.513

1. B r i n d l e y , 1959

19

2.43 2.36 2.24

_____ 2.08

1.58 1.551 1.517

7

in 14

2.44 2.39 2.259 2.117 2.071

15NR

_____

__-_-

188 5B 78

1.722 1.692

5 8

1.583 1.548 1.517

9B 10 15

142 A chemical a n a l y s i s o f t h e t r e a t e d f r a c t i o n was o b t a i n e d ( T a b l e 2) t o further characterize the sepiolite.

The r e s u l t s o b t a i n e d f r o m t h e sample,

which was impure, may be h e l p f u l i n u n d e r s t a n d i n g t h e f o r m a t i o n o f t h e sepiolite. TABLE 2 A n a l y s i s o f t h e less-than-n.2-pm f r a c t i o n o f a s e p i o l i t e - b e a r i n g sample ( i n p e r c e n t ) a f t e r a c e t i c a c i d l e a c h i n g f o r t e n days compared w i t h a n a l y t i c a l d a t a from Two Crows, Nevada, s e p i o l i t e ( P o s t , 1978). [Analysts: J. W. Baker, A. J. B a r t e l , and J. S. Wahlberg. ----- , n o t reported] Oxide

Lake Tecopa

Two Crows

58.9 4.67 3.09

53.98 0.20

Fe0 Mg0 CaO Na o K% T,ib Mn p2?5 . . Loss on 1 n i t i o n

Cf

-----

12.9 0.12 0.16 2.71 0.18 0.04 <0.05 16.26

9

_____

Total

99.03

----0.01 22.80 0.04 0.58 0.16

-----

-----

-____ ----8.46 11.54 97.77

The a n a l y s i s does n o t d e f i n e t h e chemical c o m p o s i t i o n o f t h e s e p i o l i t e v e r y well.

The a c i d t r e a t m e n t t o d e s t r o y t h e s a p o n i t e may have removed some o f t h e

magnesium from t h e s e p i o l i t e , b u t l e f t b e h i n d some o f t h e s i l i c a from t h e s a p o n i t e t e t r a h e d r a l l a y e r , t h u s a c c o u n t i n g f o r t h e a p p a r e n t l y l o w magnesium and h i g h s i l i c a .

Si02.

A f a i r l y p u r e s e p i o l i t e c o n t a i n s about 24% MgO and about 54%

P a r t o f t h e K20 can be a t t r i b u t e d t o t h e i l l i t e seen i n t h e d i f f r a c t i o n

pattern.

However, t h e alumina c o n t e n t i s t o o l o w t o a l l o w a l l o f t h e K20 t o be

i n the i l l i t e .

Some o f t h e K20 may be p r e s e n t i n p o t a s h f e l d s p a r , which has a

much h i g h e r K/A1 r a t i o and was p r e s e n t i n t h e o r i g i n a l sample b u t i s n o t c l e a r l y seen on t h e d i f f r a c t i o n p a t t e r n o f t h i s f r a c t i o n .

Because no z e o l i t e s

were seen i n any f r a c t i o n o f t h i s sample, i t i s u n l i k e l y t h a t z e o l i t e s c o u l d have c o n t r i b u t e d t o t h e K20 c o n t e n t .

Inasmuch as p a r t o f t h e alumina i s i n t h e

i l l i t e and p a r t i s i n t h e p o t a s h f e l d s p a r , t h e r e can be 1 t t l e o r no alumina i n the sepiolite. T h i s l a c k o f alumina i s c o n s i s t e n t w i t h t h e r e s u l t s o f an a t t e m p t t o s y n t h e s i z e s e p i o l it e .

Mumpton and Roy (1958) were u n a b l e t o produce s e p i o l i t e

u s i n g g e l m i x t u r e s o f MgO and Si02 t h a t i n c l u d e d alumina, b u t Hast (1956) and

143

l a t e r W o l l a s t and o t h e r s (1968) succeeded i n p r o d u c i n g s e p i o l i t e u s i n g e s s e n t i a l l y t h e same s t a r t i n g m a t e r i a l s w i t h o u t t h e alumina.

M i l l o t (1960),

I s p h o r d i n g (1973), and Heron and Johnson (1966) suggested t h a t s e p i o l i t e p r e c i p i t a t e s d i r e c t l y i n n a t u r e i f t h e pH and MgO c o n t e n t s a r e h i g h and r e a c t i v e i o n i c alumina c o n t e n t i s l o w o r n i l . SEPIOLITE FORMATION S e p i o l i t e s a r e formed i n e n v i r o n m e n t s o f h i g h pH ( a b o u t 8.0)

t h a t have

abundant s i l i c a and magnesium b u t l i t t l e o r no alumina, whereas z e o l i t e s a r e formed i n a s a l i n e environment a t a h i g h pH (above 9.0) alumina a r e a v a i l a b l e .

where b o t h s i l i c a and

It i s i n t e r e s t i n g t o n o t e t h a t w i t h i n t h e Lake Tecopa

beds t h e a l t e r e d t u f f s c o n t a i n z e o l i t e s , b u t no s e p i o l i t e o c c u r s i n e i t h e r t h e a l t e r e d o r t h e u n a l t e r e d t u f f s : i t i s found i n t h e mudstones i m m e d i a t e l y adjacent t o t h e t u f f s . The mudstones i n which s e p i o l i t e i s found i n Lake Tecopa c o n t a i n q u a r t z , mica, s a p o n i t e , c h l o r i t e , m i x e d - l a y e r m i c a - s a p o n i t e , and some p l a g i o c l a s e f e l d s p a r and d o l o m i t e , a l l o f which a r e d e t r i t a l . disseminated t h r o u g h o u t t h e mudstones.

A u t h i g e n i c c a l c i t e i s found

Z e o l i t e s and p o t a s h f e l d s p a r i n t h e

s e p i o l i t e - b e a r i n g mudstones a r e , w i t h one e x c e p t i o n each, found w i t h i n 1 meter of a tuff.

They formed w i t h i n t h e t u f f

were admixed w i t h t h e mudstones.

(Sheppard and Gude, 1968) and l a t e r

Hawkins (1981) suggested t h a t z e o l i t e s form

on o r v e r y c l o s e t o d i s s o l v i n g phases such as g l a s s because o f t h e n u t r i e n t s s u p p l i e d by t h o s e phases. The mudstones and v o l c a n i c ash were p r o b a b l y d e p o s i t e d i n waters t h a t had a pH o f 9 o r h i g h e r .

L a t e r e v a p o r a t i o n and c o n c e n t r a t i o n i n c r e a s e d t h e s a l i n i t y

and pH t o w a r d t h e c e n t e r o f t h e basin.

However, r a i n and f r e s h water from

incoming streams removed t h e c a t i o n s and l o w e r e d t h e pH a t t h e o u t e r , more exposed edges o f t h e permeable ash beds.

During d r y periods only t h e c e n t r a l

p o r t i o n o f t h e b a s i n would have been covered by t h e high-pH, waters.

high-sa;inity

Thus, t h e c e n t r a l b a s i n p o r t i o n o f t h e t u f f s would have been

z e o l i t i z e d and t h e o u t e r p o r t i o n s would have remained r e l a t i v e l y u n a l t e r e d . Sheppard and Gude (1968) r e p o r t e d t h e e x i s t e n c e o f t h i n l a y e r s o f d o l o m i t e near t h e c e n t r a l p a r t o f t h e l a k e , one below t u f f B and t h e o t h e r one between t u f f s A and B.

T h i s f i n d i n g i n d i c a t e s t h a t a t t i m e s t h e pH o f t h e waters was

above 8.0 and t h e c o n c e n t r a t i o n o f t h e magnesium was h i g h enough t o p r e c i p i t a t e d o l o m i t e ( P e t e r s o n and o t h e r s , 1963, and S k i n n e r , 1963) o r t o c o n v e r t c a l c i t e t o dolomite.

However, we found n o d o l o m i t e a s s o c i a t e d w i t h s e p i o l i t e i n o u r

study, e x c e p t f o r t r a c e amounts i n t w o sawples.

The shards o f t h e u n a l t e r e d

t u f f s c o n t a i n as much as 0.88 p e r c e n t MgO (Sheppard and Gude, 1968), which would become a v a i l a b l e f o r s e p i o l i t e f o r m a t i o n upon d i s s o l u t i o n .

Additional

144

magnesium c o u l d have been b r o u g h t i n t o t h e b a s i n i n s o l u t i o n o r as d e t r i t u s by t h e Amargosa R i v e r as i t f l o w e d f r o m t h e n o r t h t h r o u g h a r e a s c o n t a i n i n g d o l o m i t e and s a p o n i t e , a high-magnesium s m e c t i t e .

During periods o f drought

t h e c o n c e n t r a t i o n o f t h e magnesium would have ' i n c r e a s e d t h r o u g h e v a p o r a t i o n o f t h e l a k e waters.

It i s c l e a r t h a t s u f f i c i e n t magnesium was a v a i l a b l e i n t h e

central part o f the basin f o r the p r e c i p i t a t i o n o f s e p i o l i t e i f other c o n d i t i o n s were r i g h t . When t h e pH was h i g h (above 8.0)

some ash was d i s s o l v e d ,

releasing s i l i c a ,

a l k a l i s , and t h e a l k a l i n e e a r t h s t o t h e c i r c u l a t i n g w a t e r s , which c a r r i e d t h e s e elements downdip and i n t o t h e d e t r i t a l beds above and below t h e ash beds. S e p i o l i t e was n o t p r e c i p i t a t e d w i t h i n t h e n o n z e o l i t i z e d ash because, a l t h o u g h t h e c o n c e n t r a t i o n o f t h e s i l i c a i n c r e a s e d t o s a , t u r a t i o n , n e i t h e r t h e pH n o r t h e c o n c e n t r a t i o n o f t h e magnesium was g r e a t enough t o cause p r e c i p i t a t i o n .

An

i n f l u x o f f r e s h w a t e r lowered t h e pH, and t h e w a t e r became s u p e r s a t u r a t e d w i t h soluble s i l i c a .

The s i l i c a t h e n p r e c i p i t a t e d o u t as a c o l l o i d o r as s e p i o l i t e

when i t came i n t o c o n t a c t w i t h magnesium-saturated, a d j a c e n t d e t r i t a l beds.

high-pH p o r e waters i n t h e

Some s e p i o l i t e may have formed o v e r l o n g e r p e r i o d s o f

t i m e when ash, which had been m i x e d w i t h t h e d e t r i t a l sediments d u r i n g d e p o s i t i o n , was d i s s o l v e d by t h e high-pH p o r e w a t e r s and combined w i t h magnesium a l r e a d y i n s o l u t i o n . Z e o l i t e s a r e n o t found i n any s i g n i f i c a n t amounts w i t h t h e s e p i o l i t e s i n t h e a d j a c e n t mudstones because a l u m i n a c o n t e n t was i n s u f f i c i e n t t h e r e ; alumina does n o t go i n t o s o l u t i o n r e a d i l y a t a pH o f l e s s t h a n 9.5.

The small amounts o f

z e o l i t e t h a t a r e found w i t h t h e s e p i o l i t e p r o b a b l y were p r e c i p i t a t e d from t h e o r i g i n a l p o r e w a t e r s o f t h e mudstones, which had d i s s o l v e d t h e necessary s i l i c a , alumina, and a l k a l i s f r o m t h e admixed ash.

Downdip i n t h e ash beds,

z e o l i t e s were formed owing t o t h e g r e a t e r exposure t o high-pH waters. D i s s o l u t i o n o f t h e ash and t h e c o n c e n t r a t i o n o f t h e w a t e r s t h r o u g h e v a p o r a t i o n had produced a pH o f 9-10 and had c o n c e n t r a t e d t h e s i l i c a , alumina, a l k a l i s , and a l k a l i - n e e a r t h s necessary t o f o r m t h e v a r i o u s z e o l i t e s , b u t s e p i o l i t e f o r m a t i o n was p r e v e n t e d by t h e presence o f i o n i c alumina.

Sheppard and Gude

(1968) p o i n t e d o u t t h a t z e o l i t e s and o t h e r a l u m i n o s i l i c a t e s were formed d u r i n g

d i a g e n e s i s w i t h i n t h e t u f f s o r a t t h e i n t e r f a c e between t h e t u f f s and t h e a d j a c e n t beds.

T h i s p r o c e s s would have removed a l l o r most o f t h e alumina f r o m

s o l u t i o n , a f t e r w h i c h t h e w a t e r s d i s s e m i n a t i n g i n t o t h e a d j a c e n t beds above and below t h e t u f f s would s t i l l have been s a t u r a t e d w i t h s i l i c a .

A l a t e r drop i n

pH would have caused t h e s i l i c a e i t h e r t o form a c o l l o i d o r t o combine w i t h magnesium i n t h e p o r e w a t e r s t o p r e c i p i t a t e s e p i o l i t e n e a r t h e z e o l i t i z e d tuff.

A l t e r n a t e l y , s e p i o l i t e c o u l d have been formed by t h e a b s o r p t i o n o f

magnesium by t h e s i l i c a c o l l o i d , w h i c h has a g r e a t a f f i n i t y f o r magnesium.

The

145

r e s u l t i n g h y d r a t e d magnesium s i l i c a t e w o u l d have f o r m e d s e p i o l i t e when some o f t h e w a t e r was removed b y . d e s i c c a t i o n .

The s e p i o l i t e s f o u n d n e a r a l l t h e t u f f s ,

p o s s i b l y i n c l u d i n g t h o s e i n t h e samples t a k e n above t u f f A,

p r o b a b l y were

formed a u t h i g e n i c a 1 , l y i n t h i s way. O t h e r methods o f f o r m a t i o n , however, m u s t be c o n s i d e r e d f o r t h e s e p i o l i t e from 7.6-9.1

m above t u f f A and f o r a f e w anomalous o c c u r r e n c e s i n t h e

mudstones more t h a n a c o u p l e o f m e t e r s d i s t a n t f r o m t u f f s A o r B.

Direct

p r e c i p i t a t i o n f r o m s o l u t i o n , a s d e s c r i b e d b y Papke ( 1 9 7 2 ) , s h o u l d b e considered.

He s u g g e s t e d t h e p r e c i p i t a t i o n o f d o l o m i t e f o l l o w e d b y t h e

p r e c i p i t a t i o n o f s e p i o l i t e , a s t h e c o n c e n t r a t i o n o f s i l i c a was i n c r e a s e d , p r o d u c i n g a combined bed a b o u t 1.2 m t h i c k .

We d o n o t t h i n k t h i s o c c u r r e d a t

Lake Tecopa b e c a u s e n o d o l o m i t e beds o f s i g n i f i c a n t t h i c k n e s s c o n t a i n i n g a p p r e c i a b l e s e p i o l i t e were found. Because o f t h e p r e s e n c e o f m o n t m o r i l l o n i t e and c l i n o p t i l o l i t e , b o t h p r o d u c t s o f ash d e v i t r i f i c a t i o n ,

a t t h e same e l e v a t i o n as t h e s e p i o l i t e f o u n d 7.6-9.1

m

above t u f f A, we b e l i e v e t h a t t h i s s e p i o l i t e was f o r m e d i n t h e same way as t h a t associated w i t h t h e other t u f f s .

However, a n o t h e r s o u r c e o f s i l i c a must b e

c o n s i d e r e d f o r t h i s s e p i o l i t e and f o r o t h e r s c a t t e r e d s e p i o l i t e o c c u r r e n c e s i n t h e l a k e beds:

i t may h a v e come f r o m a b u n d a n t d i a t o m c o l o n i e s i n t h e l a k e .

Sheppard and Gude (1968) s t a t e d t h a t 4 2 s p e c i e s o f d i a t o m s were i d e n t i f i e d f r o m one l o c a l i t y i n t h e l a k e bed.

Some o f t h e d i a t o m s were i d e n t i f i e d as " f r e s h

w a t e r " t y p e s ; t h e s e were f o u n d , u n d e r s t a n d a b l y , i n t h e n o r t h end o f t h e b a s i n where t h e Amargosa R i v e r e n t e r e d , b r i n g i n g f r e s h w a t e r f r o m i t s l a r g e d r a i n a g e area t o t h e n o r t h .

A l a r g e amount o f s i l i c a c o u l d b e removed f r o m t h e l a k e

w a t e r s b y a f l o u r i s h i n g c o l o n y o f d i a t o m s ( P h i l l i p s and Van Denburgh, 1971). I f t h e s u p p l y o f f r e s h w a t e r were d i m i n i s h e d f o r some r e a s o n , such as a

prolonged drought, t h e r e s u l t a n t r i s e i n t h e s a l i n i t y o f t h e waters would k i l l off t h e colony. t h e water.

The o r g a n i s m s w o u l d d e c a y and t h e s i l i c a w o u l d b e d i s s o l v e d b y

S e p i o l i t e m i g h t p r e c i p i t a t e l o c a l l y wherever a colony o f diatoms

had e x i s t e d i f t h e pH were h i g h enough and a s o u r c e o f magnesium e x i s t e d .

In

s e v e r a l l o c a t i o n s where s e p i o l i t e o c c u r s , o s t r a c o d e beds have been f o u n d a l s o , i n d i c a t i n g t h e presence o f a f r e s h water i n f l u x .

A l t h o u g h we f o u n d n o d i a t o m s

a t t h e s e p i o l i t e l o c a t i o n above t u f f A, we c a n n o t r u l e o u t t h e p o s s i b i l i t y t h a t t h e y were t h e s o u r c e o f t h e s i l i c a n e c e s s a r y f o r s e p i o l i t e p r e c i p i t a t i o n i n t h e high-pH,

m a g n e s i u m - s a t u r a t e d w a t e r s o f a l a t e r l a k e phase.

Based on l a b o r a t o r y e x p e r i m e n t a t i o n and f i e l d e v i d e n c e we have c o n c l u d e d t h a t t h e Lake Tecopa s e p i o l i t e had a n a u t h i g e n i c o r i g i n .

The v o l c a n i c a s h

beds, and p o s s i b l y i n some c a s e s f o s s i l d i a t o m s , s u p p l i e d t h e n e c e s s a r y s i l ' i c a i n e i t h e r s o l u t i o n o r c o l l o i d a l f o r m t o c o m b i n e w i t h t h e magnesium i n a h i g h pH, h i g h - s a l i n i t y e n v i r o n m e n t .

146 CONCLUSIONS W o l l a s t and o t h e r s ( r 9 6 8 ) and Mumpton and Roy (1958) have shown t h a t a special environment i s necessary f o r t h e formation o f s e p i o l i t e ; i t r e q u i r e s h i g h - p H w a t e r s , s o u r c e s o f s i l i c a and magnesium, and an absence o f r e a c t i v e a l u m i n o u s phases.

I n t h e c l o s e d b a s i n o f Lake Tecopa,

evaporation and

c o n c e n t r a t i o n o f magnesium, s i l i c a , and v a r i o u s s a l t s r a i s e d t h e pH o f t h e w a t e r s t o more t h a n 8.0.

The d i s s o l u t i o n o f v o l c a n i c ash, w h i c h was

p e r i o d i c a l l y deposited i n t h e lake, c o n t r i b u t e d a d d i t i o n a l s i l i c a , which combined w i t h t h e magnesium t o f o r m s e p i o l i t e .

The r e a c t i v e a l u m i n a t h a t was

r e l e a s e d f r o m t h e a s h by d i s s o l u t i o n s e r v e d a t w o f o l d p u r p o s e .

F i r s t , i t was

n e c e s s a r y f o r t h e f o r m a t i o n o f t h e z e o l i t e s i n t h e a s h beds and a t t h e i r i n t e r f a c e w i t h t h e d e t r i t a l mud beds.

Second, t h e p r e c i p i t a t i o n o f s e p i o l i t e

w i t h i n t h e a s h beds was p r o h i b i t e d b y t h e p r e s e n c e o f a l u m i n a , b u t t h e dissemination o f t h e s i l i c a - s u p e r s a t u r a t e d waters i n t o t h e adjacent sediments above and b e l o w t h e a s h beds, where t h e s e p i o l i t e was f o r m e d i n t h e high-pH, m a g n e s i u m - r i c h p o r e w a t e r s , was n o t impeded.

I n a r e a s where n o v o l c a n i c a s h

was a v a i l a b l e , t h e s i l i c a n e c e s s a r y f o r s e p i o l i t e f o r m a t i o n may have been supplied by t h e d i s s o l u t i o n o f diatoms. REFERENCES

1959. X-ray and e l e c t r o n d i f f r a c t i o n d a t a f o r s e p i o l i t e . Am. B r i n d l e y , G.W., M i n e r a l o g i s t , 44: 495-500. H a s t , N i l s , 1956. A r e a c t i o n between s i l i c a and some magnesium compounds a t room t e m p e r a t u r e and a t +37OC. A r k i v . Kemi., 9: 343-360. Hawkins, D.B., 1981. K i n e t i c s o f g l a s s d i s s o l u t i o n and z e o l i t e f o r m a t i o n u n d e r h y d r o t h e r m a l c o n d i t i o n s . C l a y s C l a y M i n e r a l s , 29: 331-340. Heron, S.D., Jr., and Johnson, H.S., Jr., 1966. C l a y m i n e r a l o g y , s t r a t i g r a p h y and s t r u c t u r a l s e t t i n g o f t h e Hawthorn F o r m a t i o n , C o o s a w h a t c h i e d i s t r i c t , S o u t h C a r o l i n a . S o u t h e a s t e r n G e o l o g y , 7 : 51-63. I s p h o r d i n g , W.C., 1973. D i s c u s s i o n o f t h e o c c u r r e n c e and o r i g i n o f s e d i m e n t a r y p a l y g o r s k i t e - s e p i o l i t e d e p o s i t s . C l a y s C l a y M i n e r a l s , 2 1 : 391-401. MacEwan, D.M.C. a n d W i l s o n , M.J., 1980. I n t e r l a y e r and i n t e r c a l a t i o n c o m p l e x e s o f c l a y m i n e r a l s . I n : G.W. B r i n d l e y and G. Brown ( E d i t o r s ) , C r y s t a l s t r u c t u r e s o f c l a y m i n e r a l s and t h e i r X-ray i d e n t i f i c a t i o n . M i n e r a l o g i c a l S o c i e t y , London, pp. 197-248. M i l l o t , Georges, 1960. C r y s t a l l i n e n e o f o r m a t i o n o f c l a y s and s i l i c a . Proc. Symposium B a s i c Sci., France-U.S., New York U n i v . P r e s s , pp. 180-191. Mumpton, F.A. and Roy, Rustum, 1958. New d a t a o n s e p i o l i t e and a t t a p u l g i t e . C l a y s C l a y M i n e r a l s , 5: 136-143. Papke, K.G., 1972. A s e p i o l i t e - r i c h p l a y a d e p o s i t i n s o u t h e r n Nevada. C l a y s C l a y M i n e r a l s , 20: 211-215. P e t e r s o n , M.N.A., B i e n , G.S., and B e r n e r , R.A., 1963. R a d i o c a r b o n s t u d i e s o f r e c e n t d o l o m i t e from Deep S p r i n g Lake, C a l i f o r n i a . J o u r . Geophys. Res., 68: 6493-6505. P h i l l i p s , K.N. and Van Denburgh, A . S . , 1971. H y d r o l o g y a n d g e o c h e m i s t r y o f A b e r t , Summer, a n d Goose Lakes, and o t h e r c l o s e d - b a s i n l a k e s i n s o u t h c e n t r a l Oregon. U.S. Geol. S u r v e y P r o f . P a p e r 502-8, 86 pp. P o s t , J.L., 1978. S e p i o l i t e d e p o s i t s o f t h e Las Vegas, Nevada area. C l a y s C l a y M i n e r a l s, 26: 58-64.

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Sheppard, R.A. and Gude, A.J., 3rd., 1968. D i s t r i b u t i o n and genesis o f a u t h i g e n i c s i l i c a t e m i n e r a l s i n t u f f s o f P l e i s t o c e n e Lake Tecopa, I n y o County, C a l i f o r n i a . U.S. Geol. Survey P r o f . Paper 597, 38 pp. Skinner, H.C.W., 1963. P r e c i p i t a t i o n o f c a l c i a n d o l o m i t e s and magnesian c a l c i t e s i n t h e s o u t h e a s t o f South A u s t r a l i a . h . Jour. Sci., 261: 449-472. 1979. Clay m i n e r a l o g y o f P l e i s t o c e n e Lake Starkey, H.C. and Blackmon, P.D., Tecopa, I n y o County, C a l i f o r n i a . U.S. Geol. Survey P r o f . Paper 1061, 34 p p . Mountjoy, Wayne, and Gardner, J.M., 1977. Removal o f f l u o r i n e Starkey, H.C., and l i t h i u m f r o m h e c t o r i t e by s o l u t i o n s spanning a wide range o f pH. Jour. Research, U.S. Geol. Survey, v. 5, no. 2, pp. 235-242. W o l l a s t , Roland, Mackenzie, F.T., and B r i c k e r , O.P., 1968. Experimental p r e c i p i t a t i o n and g e n e s i s o f s e p i o l i t e a t e a r t h - s u r f a c e c o n d i t i o n s . Am. M i n e r a l o g i s t , 53: 1645-1662.

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149

DIAGENETIC PAI.YGORS,KITE I N MARGINAL CONTINENTAL D E T R I T A L DEPOSITS LOCATED IN THE SOUTH O F THE TERTIARY DUERO BASIN ( S E G O V I A , SPAIN) * S . LEGUEY and J . MARTIN DE VIDALES F a c u l t a d d e C i e n c i a s . U n i v e r s i d a d Aut6noma d c Madrid. S p a i n . J . CASAS

I n s t i t u t o de Edafologia y Biologia Vegetal. C . S . I . C .

S c r r a n o , l l 9 Madrid Spain.

ABSTRACT The g e n e s i s and e v o l u t i o n of c l a y m i n e r a l s h a s been s t u d i e d i n c o n t i n e n t a l d e t r i t a l d e p o s i t s , l o c a t e d i n t h e s o u t h e r n edge o f t h e T c r t i a r y Duero Basin ( S e g o v i a , S p a i n ) . The a v e r a g e t h i c k n e s s o f t h e s e m a t e r i a l s i s 40-60 m and t h r e e l i t h o l o p i c a l u n i t s a r e d i s t i n g u i s h e d , d e s c r i b e d from t h e lower t o t h e uppcr p a r t a s : a ) s i l i c c o u s s a n d s , b ) s a n d s t o n e s and p a r a c o n g l o m e r a t e s , c ) feldspathic sands with pebbles. In u n i t ( a ) t h e main c l a y m i n e r a l s a r c s m c c t i t c s which are d i s p e r s e d w i t h i n a ccmcnt formed mainly by amorphous s i l i c a and o p a l . I t i s p o s s i b l e t o r e c o g n i s e a r e a c t i o n e d g e , w i t h s m e c t i t e neoformation r i m s s u r r o u n d i n g t h e corroded p r a i n s o f q u a r t z . U n i t ( b ) i s c h a r a c t e r i s e d by t h e p r e s e n c e of c a l c a r e o u s and s i l i c e o u s cement, and f i b r o u s a g g r e g a t e s o f p a l y p o r s k i t e a t t h e i n t e r f a c e between t h e c a r b o n a t e s and t h c c o r r o d e d g r a i n s o f q u a r t z . The morphology .and development of p a l y g o r s k i t e a g g r e g a t e s changes markedly w i t h p o r o s i t y and t h e amount o f c a l c a r e o u s cement. U n i t ( c ) shows i n t h e lower p a r t s hyd r o l y s a t e d p e b b l e s o f g r a n i t e . The cement i s mainly c l a y , w i t h random o c c u r r e n c e o f c a r b o n a t e s and s i l i c e o u s m a t e r i a l s . From t h e m o r p h o l o g i c a l , m i n e r a l o p i c a l and pcochemical d a t a , t h e c l a y mine1-21 e v o l u t i o n h a s been e s t a b l i s h e d c o r r e l a t i n g w i t h t h e t e c t o n i c s t a p e s o f the Spanish C e n t r a l Range. So u n i t ( a ) c o r r e s p o n d s t o t h e e a r l i e s t "impulses" with d e p o s i t i o n i n s m a l l s l o p e d b a i n s . Oroecnic a c t i v i t y c a u s e s e r o s i o n o f c a r b o n a t i c d e p o s i t s and t h e a r r i v a l t o t h e b a s i n o f d o l o m i t i c m a t e r i a l s , which changes t h e geochemical c h a r a c t e r i s t i c s and i n i t i a t e s neoformation of palyp o r s k i t e i n u n i t b . U n i t c c o r r e s p o n d s t o t h e l a s t o r o g e n i c i m p u l s e s and rep r e s e n t s an e v o l u t i o n from p a l y g o r s k i t e and s m e c t i t e i n i t s lower a r e a s t o k a o l i n i t e and i l l i t e i n t h e uppermost INTRODUCTION T h i s s t u d y d e a l s w i t h t h e m i n e r a l o g i c a l e v o l u t i o n of t h e so c a l l e d . "Madrona formation" c o m p r i s i n g T e r t i a r y d e t r i t a l m a t e r i a l s . T h i s "formation" l i e s o v e r Upper C r e t a c e o u s d o l o m i t i c l i m e s t o n e s and m a r l s l o c a t e d i n t h e s o u t h e a s t e r n b o r d e r o f t h e Duero Basin ( S e g o v i a p r o v i n c e , S p a i n ) i n a s t r i k e r i d g e 1 2 IIKI long. I n a p r e v i o u s work ( C a s a s e t a l . . 1 9 7 5 ) i m p o r t a n t d i f f e r e n c e s i n t h e m i neralogy of t h e c l a y and sand f r a c t i o n were n o t i c e d , n o t a b l y t h e e x i s t e n c e o f f i b r o u s ( p a l y g o r s k i t e ) c l a y m i n e r a l s i n t h e c l a y f r a c t i o n , b u t i t was n o t poss i b l e i n t h a t work t o d e t e r m i n e t h e i r g e n e s i s . Other a u t h o r s have been s t u dying t h e e n v i r o n m e n t a l c o n d i t i o n s o f p a l y g o r s k i t e i n marine environments ( e . g . M i l l o t e t a l . , 1969; Hassouba and Shaw, 1980; I s p h o r d i n p , 19731, o r i n l a - ' goonary e n v i r c n n e n t s (Weaver and Beck, 1 9 7 7 ) . D i s c u s s i o n h a s a l s o extended t o

* Presented a t the International Clay Conference 1981.

W

/

STUDIED

AREA

Fig. 1.- Distribution of materials and location of profiles

151

the possible genesis of palyeorskite in edaphic formations. It has been recognised in arid and semi-arld soils (Muir, 1951; Barshad et al., 1956; Singer and Norrish, 1974; Yaalon andr'wieder, 1975; McLean et al., 1972). The proposed explanation f o r this,kind o f origin is based on diagenesis from ferro-aluminim smectites (Weaver and Beck, 1977), or inheritance from other materials rich in palygorskite. Singer (1979) has carried out a bibliographic review of-palygorskite in detrital ,sediments,discussing its possible origins. In order to discuss the possible palygorskite origin in this Tertiary formation, representative samples pere obtained from four profiles. Their petrological features were studied with the polarizing microscope and scanning electron microscope (SEM). Clay mineral identification was carried out by XRD and where necessary DTA and Infrared techniques were used. MATERIALS DESCRIPTION. Figure 1 shows schematically the distribution of materials and the location of the profiles. Three lithological units can be differentiated. From lowest to the uppermost these are: a) siliceous white sands with interbedded seams of reddish ferriferous materials. b ) sandstones and paraconglomerates. c) feldspathic sands with pebbles. The thickness of these units ranges from 45 to 60 m and the average dip in the sandstones ranges from 12 to 20 degrees. Sometimes arkoses overlie these units with an erosive unconformable contact. The sands have yellowish colours, a low degree of compaction, and contain many angular-shaped pebbles, with occasional boulders over 1 m in diameter. The sedimentological interpretation of the three.units has been given by Casas and Leguey (1976). Siliceous white sands Thickness ranges from 25 to 30 m. The sands are generally well sorted. The predominant colour is white, but there are also thin grey layers consrrining some clay (10-12%). There are also other layers with a distinct.whi-tecolour which represent medium sized sands with some cementation. Occasionally there are interbeds of red-yellowish sands 1-1.5 m thick, more continuous in the upper parts of the unit. The siliceous white sands are composed almost entirely of quartz, the grains of which, seen with the SEM, show corrosion phenomena with aureoles of transformation borders to amorphous silica (Fig. 2-A). These silicification phenomena are more intensive.in the cemented zones, where different grades of organisation of the silica can be recognised, including opal, collophorm chalcedony, and aggregates of feather-like silica, .identified by XRD as cristobalite (Jones and Segnit, 1971). Microaggregates of a subrounded shape, containing angular quartz cemented by oxides of Fe, have been recognised in the reddish sands. / In the white sand layers smectite is the predominant c/lay mineral, while in the reddish-yellowish zones, illite and kaolinite are also present. In the medium sized sand lenses, the silicification'process is more important. The cemented zones show reaction borders around quartz grains with neoformation of smectite (Fig. 2-B,

I 152

F i g . 2.A.- D i f f e r e n t g r a d e s of o r g a n i s a t i o n i n t h e s i l i c a . F i g . 2.B.- S m e c t i t e i n b o r d e r s of q u a r t z g r a i n s . Fig. 2 . C . -

F i b r o u s m i n e r a l s among t h e g r a i n s .

F i g . 3.A.-

P a l y g o r s k i t e (PL) between q u a r t z (q) and c a l c i t e ( c ) .

F i g . 3.B.-

F a n - l i k e forms o f p a l y g o r s k i t e .

F i g . 3.C.- P s e u d o - o o l i t i c c a r b o n a t e s .

153

S a n d s t o n e s and p a r a c o n g l o m e r a t e s . W i t h i n t h e "Madrona f o r m a t i o n " more compacted l a y e r s o f s a n d s t o n e s and par a c o n g l o m e r a t e s , are. p r e s e n t , i r r e g u l a r l y d i s t r i b u t e d and v a r i a b l y developed. The t h i c k n e s s o f t h e s e l a y e r s r a n g e s from 3 t o 8 m . B o u l d e r s o f d o l o m i t i c limestones d e r i v e d f?,om t h e e r o s i o n o f C r e t a c e o u s m a t e r i a l s around t h e b o r d e r o f t h e b a s i n , i n a p e r c e n t a g e o f 20% a r e p r e s e n t . The CaO&O w e i g h t r a t i o s o f t h e b o u l d e r s range between 8.5 and 1 . 4 . There a r e a l s o g r a n i t e , R n e i s s and q u a r t z b o u l d e r s . These s e d i m e n t s are f l u v i a l dep o s i t s r e l a t e d t o t h e i n i t i a l u p l i f t p h a s e s o f t h e S i e r r a d e Guadarrama. O c c a s i o n a l l y some massive whYte-violet c o l o u r e d s e d i m e n t s w i t h many s h r i n kage c r a c k s o c c u r i n t h e lower p a r t of t h e u n i t , l e s s t h a n 0,5 m t h i c k . These beds a r e composed o f p a l y g o r s k i t e , s m e c t i t e and c a l c i t e (CaO/Mg0=9.61), and c o n t a i n barium a s b a r i t e . The c h a r a c t e r i s t i c s and e v o l u t i o n o f c e m e n t a t i o n i n t h e s a n d s t o n e s a r e o f i n t e r e s t . I n t h i n s e c t i o n two p h a s e s c a n b e d i s t i n g u i s h e d : a s i l i c e o u s phase and a c a l c a r e o u s p h a s e . The r e l a t i v e p r o p o r t i o n o f each seems t o depend on t h e g r a n u l o m e t r y . I n t h e w e l l s o r t e d , f i n e - g r a i n e d s a n d s t o n e s s i l i c a cement i s more a b u n d a n t . A s p a r t i c l e s i z e i n c r e a s e s and s o r t i n g d e c r e a s e s , a h i g h e r proport i o n o f cementing c a r b o n a t e i s o b s e r v e d . A t t h e i n t e r f a c e between t h e c o r r o ded g r a i n s o f q u a r t z and t h e c a r b o n a t e cement, a f i b r o u s m i n e r a l i s observed ( F i g . 2 4 1 , i d e n t i f i e d , by XRD a s p a l y g o r s k i t e . The s i z e o f t h e c a r b o n a t e c r y s t a l s o f t h e cement i s c o n d i t i o n e d by t h e i n i t i a l p o r o s i t y , a s w e l l a s t h e morphology and t h e development o f a g g r e g a t e s o f p a l y g o r s k i t e . The zones where t h e p a l y g o r s k i t e i s more abundant a r e c o i n c i d e n t with a r e a s of good p o r o s i t y . In such a r e a s t h e s e f i b r o u s c l a y s a r e o r g a n i s e d i n i n t e r w e a v i n g a g g r e g a t e s which occupy t h e v o i d s , c o v e r i n g t h e g r a i n s o f q u a r t z ( F i g . 3 - A ) . Such f i b r e s measured w i t h SEM r e a c h a l e n g t h o f 100 pm and a w i d t h o f 0 . 1 pm . On t h e o t h e r hand, when t h c p o r o s i t y i s low, t h e aggregat e s o f p a l y g o r s k i t e a r e r a r e r , b e i n g g e n e r a l l y d i s s e m i n a t e d i n t h e cement, and t h e f i b r e s a r e a r r a n g e d i n r a d i a l f a n s w i t h a f i b e r l e n g t h up t o 2-3 p n ( F i g . 3-B).

Feldspathic sands with pebbles. Lying o v e r t h e p r e v i o u s c o n g l o m e r a t e s , a sediment o f h i g h l y v a r i a b l e g r a i n s i z e , predominant cream c o l o u r s composed o f a n g u l a r f e l d s p a t h i c s a n d s o c c u r s ( C a s a s e t a l . , 1976). These s a n d s a l t e r n a t e i n t h e lower p a r t s o f t h e u n i t w i t h l a y e r s and p a t c h e s o f g r a v e l s d i s t i n g u i s h e d by t h e i r d a r k c o l o u r s . The average t h i c k n e s s o f t h e whole u n i t i s from 2 0 t o 25 m . A l t e r a t i o n phenomena a r e p r e s e n t i n t h e form o f h y d r o l y s a t e d p e b b l e s . T h i s phenomenon a f f e c t s t h e lower l a y e r s , g r a d u a l l y d e c r e a s i n g upwards, where t h e s a n d s a r e somewhat compacted. I n t h i s zone a network o f f i n e v e r t i c a l j o i n t s i s o b s e r v e d . Angular q u a r t z , f e l d s p a r s and micas o c c u r , cemented mainly by c l a y though amorphous s i l i c a and c a r b o n a t e d cements c a n b e o c c a s i o n a l l y found. Over t h i s , a n a r k o s e bed l i e s w i t h e r o s i v e unconformity c l e a r l y d i s t i n g u i s h e d from t h e u n d e r l y i n g b e d s by lower compaction, a b s e n c e o f f r e s h b o u l d e r s , and absence o f j o i n t s . The e v o l u t i o n o f t h e c a r b o n a t e s i n u n i t C i s o f p a r t i c u l a r i n t e r e s t b e c a u s e of t h e i r p r e s e n c e i n 'the form o f w e l l developed s p a r i t i c c r y s t a l s of uniform s i z e . On t h e o t h e r hand, i n t h e a r e a s where t h e c l a y s and t h e lower p o r o s i t y a r e more o b v i o u s , t h e c a r b o n a t e s form p s e u d o - o o l i t i c c l u s t e r s ( F i g . 3.C).

154

..

In the areas of high porosity, where aggregates .of palygorskite occur, they occupy almost the whole of the voids. This diagenctic palygorskite occurs in the form of shcafs of fine crystals of silky aspcct which could be confuscd with sepjolite, because of the length and thinness o f the fibres. In the upper parts of the layers the palygorskite slow1.y deceeases in cor.formity with decreasing carbonate contents. The clay fraction constitutes 10-15% o f the samples, and is composed of palygorskite, smectite, kaolinite, illitc and mixed layer illite-smectite. From the lower to the upper parts o f the unit, one passcs ?om dominant palygorskite and smectite in the lower layer through an intermediate zone where the content of illite and kaolinite is increased, to the, upper part where the fibrous minerals disappear (although they can occasionally be sccn in clay seams as a consequence of a rcworking process from the underlying deposits). DISCUSSION OF RESULTS. The composition and cvolution of the studied materials are directly related to the interplay between the late stages of biostasia of the Pre-alpine perieplain, and the erosive activity originating from uplift of the Guadarrama Range. The lithological unit (a) of whitish sands with predominantly transported quartz corresponds to small slope deposits related to the formation of small basins (SBnchez de la Torre, Oviedo University, personal communication) and to runoff waters from the erosion of arid and semi-arid soils. Under such conditions the pH was probably basic, because measured values of pH range from 7 . 6 to 8.3. According to Turner (1980) solution of silica is thcn favoured, producing different grades o f crystalline organisation depending on the initial degree of porosity of the materials. In clayey sediments with low porosity there is slight corrosion of quartz grains as well as formation of undifferentiated cement of amorphous silica. When the materials are coarser, the corrosion is more intensc 2nd sequence of opal with two types of organisation can be recognised as well as chalcedony and cristobalite. Together with this process, and under maximal conditions of porosi-ty, smcctites are observed to surround the borders of quartz grains. These clays are believed t o be neoformed. High porosity facilitates incorporation into the sediment of alkaline and alkaline-earth elements which reacted with the silica to form smectitc (Garrels and Christ, 1965). The ferriferous horizons within the white sands are related to the erosion of ferrisialitic soils in coincidence with the earliest impulses of the tectonic movements. . The alkaline character of the environment, with a pH - 8, favoured the neoformation of smectites as well as the mobilisation and irregular dispersion of iron which gives these materials their typical colour. The orogenic activity is shown by the presence of coarse polygenetic sediments, in-unit ( b ) , (with granite, gneiss, dolomite limestones and quartzite pebbles) which are rel.ated to alluvial deposits with an irregular, horizontal , . distribution. The arrival of dolomitic materials introduces important changes, in the geochemical composition of the basin. The alkalinity of the environment increases-(pH about’8.5), silica concentration increases and calcite precipitates, producing a magnesium rich solution. The mechanism is similar to the

CHEMICAL AlpOl

SiO,

CHARACTERISTICS ( 1 )

M p o COO

7.4 21,9 3,12

1,6

Fa0

1,5

K20 0th.r

pH

MINERALS (grain size) 0,12 mm

HEAVY

Mrosurrd

o,m

CLAY MINERALOGY

EVOLUTION

a

3,3 0,2 (*)

( T = 99,02 )

5,s 21,5 l2,5 5 , 8

1,8 ( T = 33.88)

1,6

L a w con?nbutlon af CO; Arrival of arkosic matorbl Gonosir of !+noctitr and mired layers

0,18(*)

a

-

1

8,7 9,22 7,04 33,79 0.8 0,38 ( T- 99,93 7,4 7,65 5.41 4,9 O,7 ( T=100,4 1

!,15 19,6

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m

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1,79

Silici t lcation CaMg(CO,)+CaCO,+

(T:100,56)

1,9 12,3 1,89 0,9 (T=99.88)

7 8 9 Tourmoline

Q

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(**)BaO (mainly in form d SO4&) (1)-

T

-

Af?er COJ

Total

eliminatior

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Si I i c i f i c o tion

Dittmren? ordoring of silica according to pomdahon Mallmum p.rcolation

+ Stnutile

gonesir

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0Andalusitr

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a a F i g . 4.-

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3

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Kyonitr Staurolitr Rutilr

Morphological, c h e m i c a l and m i n e r a l o g i c a l e v o l u t i o n of t h e basin.

Malorial8 drpoating

Yosoxoic Basoman1

wdimrntr

during

Tortiary

ago

156

one d e s c r i b e d by B e r n e r ( 1 9 7 1 ) f o r t h e r e a c t i o n : 2+

-

2+

co 0 . 5 Mg + ' Cai03; K = 0 . 8 2 0 . 5 Mg0.5 3 aq T h i s r e a c t i o n c a n t a k e p l a c e only i n calcium r i c h w a t e r s . T h e r e f o r e s i l i c a and magnesium p l a y an i m p o r t a n t geochemical r o l e i n t h i s b a s i n , l e a d i n g i n a f i r s t s t a g e t o t h e f o r m a t i o n o f magnesium S m e c t i t e , and i n t h e f i n a l s t a g e , t o t h e n e o f o r m a t i o n o f p a l y g o r s k i t e a s t h e mair c l a y m i n e r a l . T h i s p r o c e s s shows a c t i v i t y o f Fe and A 1 was d e c r e a s i n g a l o n g t h i s u n i t . T h e r e f o r e t h e pen e s i s o f p a l y p o r s k i t e i s e x p l a i n e d by e a r l y d i a g e n e s i s a s a consequence o f t h e r i c h magnesium c a r b o n a t e s o l u t i o n . These came i n t o t h e baSin a s a r e s u l t o f d i s s o l u t i o n o f d o l o m i t i c m a t e r i a l s from t h e :Cretaceous, : m o b i l i s e d d u r i n g an e r o s i v e p h a s e . The s o l u t i o n became more c o n c e n t r a t e d in'mapnesium by p r e c i p i t a t i o n o f c a l c i t e , and t h e Mgtt r e a c t e d i n t h e p o r e s o f t h e g r a i n s w i t h t h e amorphous s i l i c a s u r r o u n d i n g t h e q u a r t z , and so t h e p a l y g o r s k i t e was formed. The f i b r e s i z e and d i s t r i b u t i o n o f p a l y g o r s k i t e i s c o n t r o l l e d by t h e p r e s e n c e o f q u a r t z g r a i n s w i t h r i m s o f o p a l as w e l l a s t h e r e l e a s e o f Mp t o t h e environment and t h e g e n e r a l p o r o s i t y o f t h e d e t r i t a l components. P o r o s i t y cont r o l s t h e p r e c i p i t a t i o n o f t h e c a l c a r e o u s cement, and t h e r e a c t i o n o f s i l i c a w i t h t h e r e l e a s e d Mg, which p r o d u c e s t h e p a l y p o r s k i t e . The s p a c i a l d i s t r i b u t i o n o f t h e p a l y g o r s k i t e i s a l s o i n f l u e n c e d by t h e g r a i n s i z e d i s t r i b u t i o n and l i t h o l o g y of t h e d e t r i t a l d e p o s i t s . The c l a y miner a l a g r e g a t e s a r e more abundant i n t h e conglomerate l a y e r s w i t h d o l o m i t i c bould e r s t h a n i n t h e s a n d s t o n e s , where t h e c a r b o n a t e o n l y a p p e a r s i n t h e cement p h a s e . T h i s a l s o a f f e c t t h e g e o g r a p h i c d i s t r i b u t i o n o f t h e p a l y p o r s k i t e becaus e t h e s a n d s t o n e s l a y e r s a r e more f r e q u e n t towards t h e e a s t e r n b o r d e r o f t h c s t u d i e d zone. The s e d i m e n t s o f u n i t C which o v e r l y t h e c o n g l o m e r a t e s a r e c h a r a c t e r i s e d by f a n s composed o f f e l d e s p a t h i c s a n d s . O c c a s i o n a l l y , t h e s e a r e v e r y c l a y e y , o r sometimes o c c u r i n t e r l a y e r e d w i t h b e d s o f b o u l d e r s . The c o m p o s i t i o n a l changes o f t h e c l a y m i n e r a l s observed i n t h i s u n i t a r e v e r y s i g n i f i c a n t . Mainly i n t h e l o w e r p a r t , o r i n a r e a s o f h i g h p o r o s i t y , pal y g o r s k i t e i s p r e d o m i n a n t , b u t d e c r e a s e s upward o r when t h e p o r o s i t y i s l o w e r . Under t h i s l a s t c i r c u m s t a n c e t h e c a r b o n a t e s a r e m a n i f e s t e d by i s o l a t e d o o l i t i c clusters of c a l c i t e within the clay matrix. As p a l y g o r s k i t e d e c r e a s e s , t h e p r e s e n c e o f k a o l i n i t e and s a e c t i t e s becomes more s i g n i f i c a n t , and so a l s o d o micaceous m i n e r a l s ( i . e . i l l i t e and mixeil-lay e r s m i n e r a l s ) . Occasionally, i n upper l a y e r s a l s o palygorskite can be found, p r o b a b l y coming from t h e reworking o f a d j a c e n t zones. The m o r p h o l o g i c a l , chemical and m i n e r a l o g i c a l e v o l u t i o r o f t h e b a s i n i s described i n Fig. 4. 0.5 C a

t

Ca

AKNOWLEDGEMENT.

We are i n d e b t e d t o Dr. J . Medina f o r h e l p w i t h SEM o b s e r v a t i o n s , t o M r . G . Limia and M.Jolgado f o r t h e i r c o l l a b o r a t i o n a n d t o t h e r e f e r e e s and e d i t o r s f o r c r i t i c a l comments OR t h e m a n u s c r i p t .

157

REFERENCES Barshad, H . , Halevy, E . , Gold, H . A . and Hagin, J . , 1956. Clay m i n e r a l s i n some l i m e s t o n e s o i l s o f I s r a e l . S o i l S c i . , 81:423-437. Berner, R . , 1971. P r i n c i p l e s o f Chemical Sedimentology. McGraw-Hill Book Company, N e w York, 240 pp. Caszs, J . , Leguey, S . and Rodriguez, J . , 1975. K a o l i n i t e e v o l u t i o n i n t h e A l b i a n and O l i g o c e n i c s e d i m e n t s i n t h e Northern b o r d e r o f Guadarrama Mountains (Segovia, S p a i n ) . Travaux du Comite I n t e r n a t i o n a l pour l ' e t u d e d e s B a u x i t e s , l ' a l u m i n e e t d ' a l u m i n i u n (ICSOBA) num. 13:91-101. Casas, J . and Leguey, S . , 1976. E s t u d i o s e d i m e n t o l o g i c o d e 10s m a t e r i a l e s d e t r i t i c o s . d e 1 b o r d e n o r t e d e l a S i e r r a d e Guadarrama. B o l e t i n d e G e o l o g i a . M i n i s t e r i o d e Minas e H i d r o c a r b u r o s d e Venezuela. P u b l i c a c i o n e s p e c i a l num. 7, Tom0 1 1 , 1027-1040. Garrels, M . R . and C h r i s t , C . L . , 1965. S o l u t i o n s , M i n e r a l s and E q u i l i b r i a . Harper, New York, 450 p p . Hassouba, H . and Shaw, H . F . , 1980. The o c c u r r e n c e of P a l y g o r s k i t e i n Quaternary s e d i m e n t s o f t h e C o a s t a l P l a i n o f North-West Egypt. Clay M i n e r a l . , 15:77-83. I s p h o r d i n g , W . C . , 1973. D i s c u s s i o n o f t h e o c c u r r e n c e and o r i g i n of s e d i m e n t a r y p a l y g o r s k i t e - s e p i o l i t e d e p o s i t s . C l a y s Clay Miner. 21:391-401. J o n e s , J . B . and S e g n i t , E . R . , 1971. G e n e s i s o f c r i s t o b a l i t e and t r i d y m i t e a t low t e m p e r a t u r e . Geol. SOC. Aust. 18:419-422. McLean, S . A . , A l l e n , B . L . and C r a i g , J . R . , 1972. The o c c u r r e n c e of- s e p i o l i t e and a t t a p u l g i t e on t h e s o u t h e r n High P l a i n s . Clays Clay Miner. 20:143-219. M i l l o t , G . , P a q u e t , H . and R u e l l a n , A . , 1969. Neoformation d e l ' a t t a p u l g i t e d a r s l e s s o l s a c a r a p a c e s c a l c a i r e s d e l a Basse Moulouya (Maroc O r i e n t a l ) C . R . Acad. S c i . P a r i s 268:2771-2774. Muir, A . , 1951. Notes on S y r i a n s o i l s . J . S o i l S c i . 2:163-181. S i n g e r , A . , 1979. P a l y g o r s k i t e i n Sediments: D e t r i t a l d i a g e n e t i c o r neoformed a c r i t i c a l r e v i e w . Geol. Rundschau 68:996-1008. S i n g e r , A . and N o r r i s h , K . , 1974. Pedogenic p a l y g o r s k i t e o c c u r r e n c e s i n A u s t r a l i a . Am. Miner. 590:508-517. T u r n e r , P . , 1980. C o n t i n e n t a l Red Beds. E l s e v i e r S c i e n t i f i c P u b l i s h i n g Company. Amsterdam-Oxford-New York. Weaver, C . E . and Beck, K . G . , 1977. Miocene o f t h e S.E. United S t a t e s : a model f o r chemical s e d i m e n t a t i o n i n a p e r i m a r i n e environment. Sedim. Geol. 17: 1-234. Yaalon, D . H . and Wieder, M . , 1976. Pedogenic p a l y g o r s k i t e i n some a r i d brown ( C a l c i o r t h i d ) s o i l s o f I s r a e l . C l a y Miner. 11:73-80.

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159

BALLARAT SEPIOLITE, I N Y O . COUNTY , CALIFORNIA J. L . P o s t and N . C. Janke Department o f C i v i l E n g i n e e r i n g and Department of Geology C a l i f o r n i a S t a t e U n i v e r s i t y , Sacramento, C a l i f o r n i a (U.S.A.) ABSTRACT B a l l a r a t s e p i o l i t e appears t o have formed by a l t e r a t i o n o f p r e v i o u s l y e x i s t i n g m i n e r a l s , p r i m a r i l y s a p o n i t e , r a t h e r t h a n by d i r e c t c r y s t a l l i z a t i o n , during c y c l i c inundation b y a Pleistocene lake.

The s e p i o l i t e appears as a

c o a t i n g on f r a c t u r e s u r f a c e s o f metamorphosed 1 imestone i n c o m b i n a t i o n w i t h s a p o n i t e and d i o p s i d e . B a l l a r a t s e p i o l i t e o c c u r s as a n a t u r a l l y p u r e and w e l l c r y s t a l l i z e d m a t e r i a l , v e r y s i m i l a r t o Two Crows s e p i o l i t e f r o m Nevada, so t h a t i t s d i f f r a c t i o n p a t t e r n has more peaks r e s o l v e d t h a n p a t t e r n s o f s e p i o l i t e g i v e n f o r specimens from o t h e r sources, such as Kuzu, Japan.

Also, t h e i n f r a r e d a b s o r p t i o n s p e c t r a

a r e more s h a r p l y d e f i n e d . INTRODUCTION D u r i n g t h e i n v e s t i g a t i o n o f a d i o p s i d e d e p o s i t i n t h e s o u t h e r n p a r t of Panamint V a l l e y s e v e r a l o u t c r o p s o f w h i t e c l a y e y m a t e r i a l were observed t o b e m o i s t a t s h a l l o w d e p t h under e x t r e m e l y h o t and d r y c o n d i t i o n s .

The c l a y e y

m a t e r i a l was found t o be s a p o n i t e , o c c u r r i n g i n f r a c t u r e zones i n l i m e s t o n e , w i t h sheets o f s e p i o l i t e l i n i n g t h e upper p a r t o f some f r a c t u r e zones.

The

purpose o f t h i s paper i s t o d e s c r i b e t h e o r i g i n and n a t u r e o f t h e s e p i o l i t e . The c l a y d e p o s i t s o c c u r a b o u t 3 k i l o m e t e r s n o r t h e a s t o f t h e g h o s t m i n i n g town o f B a l l a r a t ( F i g . 1 ) and have been d e s c r i b e d b r i e f l y by P o s t (1981). The c l a y d e p o s i t s a r e a t an e l e v a t i o n o f 90 t o 150 m above South Panamint Playa ( e l e v . 317 m) on t h e w e s t f l a n k o f t h e Panamint Range.

The t e r r a i n i s

p r e c i p i t o u s , c u l m i n a t i n g i n Telescope Peak a t 3350 m e l e v a t i o n w i t h Death Valley t o the east.

The summer ground s u r f a c e t e m p e r a t u r e s exceed 75OC w i t h

r e l a t i v e h u m i d i t y o f l e s s t h a n 10 p e r c e n t and average annual p r e c i p i t a t i o n of about 75 mm. The Panamint V a l l e y p l a y a s a r e t h e remnants o f a l a r g e P l e i s t o c e n e l a k e (Lake Panamint) which has f i l l e d t h e v a l l e y a t l e a s t f i v e t i m e s t o a maximum d e p t h o f a b o u t 284 m i n t h e l a s t 100,000 y e a r s (Smith, 1976). l a s t p a r t i a l l y f i l l e d as r e c e n t l y as 15,000 y e a r s ago.

The l a k e was

A summary o f o u t s t a n d -

i n g c o n t r i b u t i o n s t o t h e i n v e s t i g a t i o n o f p l a y a b a s i n s , i n c l u d i n g Panamint V a l l e y , i s g i v e n by Neal (1975).

Contained t h e r e i n i s a d i s c u s s i o n o f t h e

i n v e s t i g a t i o n o f c l a y m i n e r a l s i n t h e sediments o f t h e Panamint Playas (Droste. 1961).

160

+

Y

TELESCOPE PEAK

0

KILOMETERS 5

10

F i g . 1. The s e p i o l i t e d e p o s i t occurs near G a l l a r a t , C a l i f o r n i a . Trona and o t h e r s a l t s , which a r e r e c o v e r e d from S e a r l e s Lake, a r e n o t found i n South Panamint Playa. The c l a y s u i t e s i n c o r e samples i n Panamint V a l l e y show l i t t l e v a r i a t i o n w i t h depth, and t h e m o n t m o r i l l o n i t e : i l l i t e : c h l o r i t e : a n d / o r k a o l i n i t e r a t i o t y p i c a l l y i s 5 : 3 : 2, a c c o r d i n g t o D r o s t e . F u r t h e r , t h e e v a p o r j t e s a r e r i c h i n sodium and calcium, and magnesium s a l t s a r e e x t r e m e l y r a r e . The c l a y s u i t e s d o n o t suggest t h a t t h e S e a r l e s B a s i n sediment has been t r a n s p o r t e d i n t o Panamint V a l l e y d u r i n g t h e f i l l i n g o f t h e two b a s i n s .

161

Origin o f sepiolite

A p r e l i m i n a r y i n v e s t i g a t i o n o f t h e geology o f t h e a r e a was done by Murphy (1932) which i n v o l v e d m a i n l y g o l d m i n i n g p r o p e r t i e s .

A recent investigation

of t h e geology o f t h e area b y Labotka (1978) i n c l u d e s a s t u d y o f t h e r e g i o n a l metamorphism.

The s t u d y o f P l e i s t o c e n e l a k e s by Smith (1976) a l s o i n c l u d e s an

i n v e s t i g a t i o n o f r e c e n t t e c t o n i c d i s p l a c e m e n t s i n t h e area. The tough, p a r c h m e n t - l i k e f i b r o u s masses o f s e p i o l i t e o c c u r as c o a t i n g s and a r e found p r e d o m i n a n t l y i n t h e n e a r - v e r t i c a l j o i n t s and f r a c t u r e s o f metamorphosed L a t e Cambrian Noonday d o l o m i t i c l i m e s t o n e near t h e w e s t e r n base o f t h e mountains.

The s e p i o l i t e samples s t u d i e d were o b t a i n e d f r o m o u t c r o p s w e l l

below t h e l o w e s t o b s e r v a b l e P1 i o - P l e i s t o c e n e t e r r a c e s formed b y t h e e x t i n c t Lake Panamint. D u r i n g t h e e v a p o r a t i o n o f t h e l a r g e l a k e most o f t h e more s o l u b l e m i n e r a l s c o n t a i n i n g Na and Ca have been r e d i s s o l v e d and have dropped w i t h t h e w a t e r t a b l e w h i l e t h e Mg s a l t s were t a k e n up i n t h e f o r m a t i o n of new m i n e r a l s i n The s e p i o l i t e appears t o have formed a t t h e

c l u d i n g s a p o n i t e and s e p i o l i t e .

expense o f t h e s a p o n i t e because t h e s a p o n i t e i n t h e f r a c t u r e and f i s s u r e c a v i t i e s i s b e l i e v e d t o have formed e a r l i e r , p o s s i b l y i n P l i o c e n e times, and t h e s a p o n i t e was t h e o n l y s i g n i f i c a n t s o u r c e o f Mg a v a i l a b l e . Weaver and P o l l a r d (1973, p. 30) have r e f e r e n c e d s e v e r a l a u t h o r s who have found s e p i o l i t e i n modern l a c u s t r i n e d e p o s i t s .

F l i l l o t (1970, pp. 172-174)

i n d i c a t e s t h a t p o l y g o r s k i t e and s e p i o l i t e o c c u r i n c e r t a i n f o s s i l l a k e s t h a t have t h e f o l l o w i n g c h a r a c t e r i s t i c s i n common: and h y p e r s a l i n i t y . a pH l e s s t h a n 8.

presence o f carbonates, c h e r t ,

V e l d e (1977) a l s o i n d i c a t e s t h a t s e p i o l i t e i s n o t s t a b l e f o r The B a l l a r a t s u r f a c e c l a y now has a pH o f a b o u t 7.

The age

r e l a t i o n s a r e i m p l i e d b y t h e p e r i o d s o f l a k e - f i l l i n g and e v a p o r a t i o n t h a t produce such an environment,

i.e.,

P l e i s t o c e n e back t o P l i o - P l e i s t o c e n e ( e a r l i e s t

p l u v i a l times) f o r t h e s e p i o l i t e . The m i n e r a l s most commonly a s s o c i a t e d w i t h t h e s e p i o l i t e i n t h e l i m e s t o n e f i s s u r e s a r e s a p o n i t e and c a l c i t e , w i t h shards o f d i o p s i d e and t r e m o l i t e , and t h e most common n e a r - s u r f a c e e v a p o r i t e s i n c l u d e gypsum, h a l i t e , and t h e n a r d i te. I t has been observed t h a t t h e B a l l a r a t s e p i o l i t e exposed a t t h e s u r f a c e has n o t been r e a d i l y a l t e r e d by w e a t h e r i n g whereas t h e Two Crows s e p i o l i t e ( P o s t , 1978), exposed i n a r o a d c u t i n s i m i l a r c l i m a t e , had begun t o d i s i n t e g r a t e . CHARACTERISTICS OF SEPIOLITE The s e p i o l i t e o c c u r s as f l a t p l a t e s on f r a c t u r e s u r f a c e s w h i c h may b e more t h a n one m e t e r across and more t h a n t h r e e c e n t i m e t e r s t h i c k , and t h e s e p i o l i t e sometimes o c c u r s as m o i s t , t h i n , f l e x i b l e s h e e t s i n t h e s a p o n i t e .

The s e p i o -

l i t e c o n t a i n s few i m p u r i t i e s and apears v e r y c r y s t a l l i n e i n t h a t t h e d i f f r a c tion

p a t t e r n c o n t a i n s many c l e a r l y r e s o l v e d peaks, t h u s q u i t e s i m i l a r t o t h e

162

Two Crows s e p i o l i t e described by Post (1978).

Because o f t h e s i m i l a r i t y a

comparison o f t h e p r o p e r t i e s o f t h e two s e p i o l i t e m i n e r a l s i s given. X-ray powder d i f f r a c t i o n Loosely packed powder samples were scanned u s i n g a P i c k e r X-ray d i f f r a c t o meter w i t h a d r i v e r a t e o f lr2Q/min i n c o n j u n c t i o n w i t h a 1' divergence s l i t , 0.002 i n r e c e i v i n g aperture, and a N i - f i l t e r e d Cu r a d i a t i o n .

The r e s u l t s f o r

t h e B a l l a r a t s e p i o l i t e a r e given i n Table 1 f o r r e f l e c t i o n s through 44'2Q

angle.

TABLE 1 Observed s e p i o l i t e X-ray powder d i f f r a c t i o n p a t t e r n f o r m a t e r i a l r e p r e s e n t a t i v e o f t h e B a l l a r a t area i n comparison t o t h e p a t t e r n f o r s e p i o l i t e from t h e Kuzu D i s t r i c t , Japan.

The peak i n t e n s i t i e s a r e n o t a d j u s t e d f o r scanning angle. Sepiolite d i f f r a c t i o n patterns

Ballarat, California hKa

d i

110 130 200 150 060 131 221 260 241 080 331 261 081 510 44 1 022 371 ;191 202;042 461 312 ;2,10,1 2,12,0 082 60 1

12.20 7.60 6.70 5.025 4.503 4.304 3.992 3.746 3.545 3.354 3.186 3.057 2.829 2.677 2.620 2.578 2.558 2.445 2.400 2.259 2.131 2.074 2.057

*(Nagata,

I 31 5 23 10 6 24 26 2 B 21 6 26 17 10 3 12 15 13 23 8 7 12 3 7 6

Kuzu O i s t r i c t , Japan h Ka

d i

*

I

110 130 200 ;040 01 1 ;150 03 1 131 221 231 ;260 24 1 400 ;080 331 261 41 1 460 51 0

12.23 7.531 6.732 5.036 4.51 5 4.324 3.997 3.759 3.542 3.360 3.198 3.054 2.831 2.690 2.623

vs 45 65 25 85 85 20 100 35 180 100 40 10 90 65

191 202;212; 291 38 1 062;312,2,10,1 3,10,1 402

2.565 2.449 2.405 2.260 2.124 21072

75 40 40 55 20 65

e t a l , 1974)

The d i f f r a c t i o n peak i n d i c e s were taken from d a t a compiled by C a i l l e r e and Henin (1961).

The d i f f r a c t i o n peak i n d i c e s a r e c a l c u l a t e d on t h e b a s i s o f t h e

Pncn (or Pnan) orthorhombic space group. Japan

Data f o r s e p i o l i t e from Kuzu D i s t r i c t ,

(Nagata, e t a l , 1974) a r e i n c l u d e d f o r comparison.

Additional calculated

163 i n d i c e s f o r peaks l e s s than 2.038A d- spacing a r e g i v e n by Borg and Smith (1969). The p a t t e r n i s v e r y s i m i l a r t o t h e d i f f r a c t i o n p a t t e r n f o r Two Crows sepiol i t e , which i s unusual because o f t h e c o n s i d e r a b l e v a r i a t i o n i n t h e number o f observed s e p i o l i t e d i f f r a c t i o n p a t t e r n s and t h e i r i n t e n s i t i e s ( B r i n d l e y , 1980, p. 188).

The p r i m a r y 110 r e f l e c t i o n a t 12.OOj i s v e r y c l o s e t o t h e value o f

0

12.10A f o r t h e Two Crows s e p i o l i t e as expected because t h e A1203 contents a r e n e a r l y t h e same. I n f r a r e d Spectra The i n f r a r e d a b s o r p t i o n s p e c t r a were o b t a i n e d f o r b o t h B a l l a r a t and Two Crows s e p i o l i t e specimens u s i n g K B r d i s c s .

A Perkin-Elmer 337 g r a t i n g i.r.

spectrophotometer having a l i g h t frequency response v a r y i n g from 4000 t o 400 cm-l was used i n c o n j u n c t i o n w i t h a f a s t scan r a t e , normal s l i t s , and an a i r beam a t t e n u a t o r .

The peak p o s i t i o n s were checked b y comparison w i t h a

standard p o l y s t y r e n e sample spectrum. The i.r. s p e c t r a f o r t h e two d i f f e r e n t s e p i o l i t e specimens are very n e a r l y the same (Table 2) even t o t h e e x t e n t o f r e l a t i v e i n t e n s i t y o f t h e spectrum bands.

The i.r. spectrum o f t h e Kuzu D i s t r i c t s e p i o l i t e (Nagata, e t a l , 1974)

i s i n c l u d e d f o r purposes o f comparison.

The broad bands caused by adsorbed

water occurred near 3435 cm-l wave number f o r b o t h specimens.

No specimen pre-

treatment was done. V i b r a t i o n a l modes were assigned t o t h e h y d r o x y l s t r e t c h i n g r e g i o n according t o those suggested by Hayashi, e t a1 (1969).

Farmer has suggested t h a t t h e

band near 3259 cm-l may be due t o i n t e r l a y e r water (1958, p. 841). o f moderate i n t e n s i t y which occur a t 1645 cm-'

Broad bands

f o r t h e B a l l a r a t specimen, and

1650 cm-l f o r t h e Two Crows specimen, a r e assigned t o z e o l i t i c water bending mode (Hayashi, e t a l , 1969).

V i b r a t i o n a l modes comparable t o those of t a l c

(Farmer, 1958) a r e found f o r t h e s e p i o l i t e i n c l u d i n g p o s s i b l e Si-0 bonds near 1078 and 1022 cm-1 , and a g a i n near 687 and 638 cm-'

, and

p o s s i b l e Mg-0 bonds

near 530 and 452 cm-l wave number. Thermal C h a r a c t e r i s t i c s

A Perkin-Elmer DTA 1700 thermal a n a l y z e r was used w i t h a h e a t i n g r a t e of 20°C per min through a range from 25OC t o 1120°C w i t h an alundum r e f e r e n c e and n i t r o g e n purge.

Endotherms f o r t h e B a l l a r a t s e p i o l i t e specimen occur a t 14OoC

and 345OC w i t h another endotherm a t 824OC i m n e d i a t e l y fo'llowed by an exotherm a t 838OC. The thermogram f o r t h e B a l l a r a t s e p i o l i t e specimen i s comparable t o t h e deh y d r a t i o n p a t t e r n f o r t h e Two Crows s e p i o l i t e . specimen (Post, 1978) and f o r the data f o r f i b r o u s s e p i o l i t e g i v e n by C a i l l e r e and Henin (1957).

The water l o s s

164

TABLE 2 Observed i n f r a r e d s p e c t r a o f B a l l a r a t , C a l i f o r n i a , and Two Crows, Nevada, s e p i o l i t e i n t h e r e g i o n o f 4000 t o 3200 cm-l and 1300 t o 400 cm-l frequency. The f i r s t f o u r bands a r e assigned OH s t r e t c h i n g v i b r a t i o n a l modes comparable t o those assigned t o Kuzu D i s t r i c t s e p i o l i t e (Hayashi, e t a l , 1969), and t h e f i f t h band as suggested by Farmer (1958).

S e p i o l i t e i n f r a r e d spectra Two Crows, Nevada

Ballarat, California 1 Freq.(cm- ) I n t e n s

Freq.(cm-l)

Intens

Kuzu D i s t r i c t , Japan* 1 ) I n t e n s V i b r a t i o n a l Mode

Freq.(cm3688 3650 3623 3563

w w w

1197

b

1073 1017

m

974

m

783

m

727 690 648 533

W

OH t a l c - l i k e l a y e r OH bound w a t e r OH z e o l i t i c water m OH z e o l i t i c water OH i n t e r l a y e r W W water ____________----____------------------------------------------------------------

3715 3660 3640 3585 3245

1213 1197 1143 1113 1078 1022 1000 977 885 784 761 723 687 638 530 49 0 452 44 0

*(Nagata,

3705 3650 3630 3570 3255

W

vw vw m

wm w infl infl ms

W

vw vw m

1206 1192 1130 1100 1072 1024 1002 976 888 785 764 720 688 644 533 500 467 44 2

S

ms S

infl W

vw vw wm wm VW

vw S

m

m

w infl infl ms S

S

ms S

vw W

vw vw wm wm W

m m W

vw 467 432

S

m

m W

e t a l , 1974)

I n t e n s i t y values:

s b

-

-

strong; m broad

-

moderate; w

-

weak; i n f l

-

inflection;

upon dehydration, f o l l o w i n g t h e concepts o f Weaver and P o l l a r d (1973), based upon specimen w e i g h t when heated t o 25OoC, i s 10.99 p e r c e n t (25O-25OoC) zeo-

l i t i c water, 5.07

p e r c e n t (25Oo-62OpC) bound water, and 4.01 p e r c e n t

(62O0100O0C) hydroxyl water.

blhen f i r e d t o 1O5O0C c l i n o - e n s t a t i t e i s formed 0

w i t h t h e dominant d i f f r a c t i o n peak a t 2.879A.

165

Chemical A n a l y s i s

A specimen o f B a l l a r a t s e p i o l i t e was analyzed u s i n g a P i c k e r X-ray f l u o r e s cence appdratus. troscopy.

The sodium c o n t e n t was determined by atomic a b s o r p t i o n spec-

The r e s u l t s o f t h e a n a l y s i s ( T a b l e 3) a r e s i m i l a r t o t h e composition

o f Two Crows s e p i o l i t e b u t show a lower A1203 c o n t e n t than t h e Kuzu D i s t r i c t sepiolite.

The s e p i o l i t e composition i s much l i k e t h e s e p i o l i t e analyses g i v e n

by Weaver and P o l l a r d (1973, p. 128).

For purposes o f XRF a n a l y s i s t h e data

r e s u l t s a r e g i v e n f o r 250°C as w e l l as 25OC. TABLE 3 Chemical a n a l y s i s o f B a l l a r a t s e p i o l i t e ( p e r c e n t ) as determined by X-ray fluorescence a n a l y s i s (25OOC) , and a d j u s t e d f o r z e o l i t i c water (25OC).

Na c o n t e n t was determined by atomic a b s o r p t i o n scpectrophotometry.

The The analyses

of Two Crows s e p i o l i t e and Kuzu D i s t r i c t s e p i o l i t e a r e i n c l u d e d f o r purposes of comparison. Chemical analyses o f s e p i o l i t e specimens Ballarat, California 250°C, % 25OC, % Si02

Kuzu D i s t r i c t , Japan amb., %

62.12

55.26

53.98

0.22

0.19

0.20

1.03

0.27

0.24 0.04 1.97 22.64 0.14

0.01

0.05

0.04 22.80 0.58

0.01 0.51 23.74

2'3 Fe203 MnO CaO r.igo Na20

Two Crows, Nevada' amb., %

0.05 2.21 25.45 0.15

52.85

K2O+

0.03

0.03

0.16

H20 H 20-

9.08

8.08 10.99 99.58

8.46

9.04

11.54 97.77

12.67 99.89

~

99.58 '(Post,

1978)

'(Otsuka,

2

1968)

A specimen of s e p i o l i t e from t h e B a l l a r a t d e p o s i t contained 780 ppm (0.08%) F-, i n comparison t o analyses from f o u r nearby p r e v i o u s l y described s e p i o l i t e deposits (Post, 1978) w i t h 0.27%, 0.98%, 1.19%, and 1.31% F- c o n t e n t f o r sepiol i t e from N o r t h Las.Vegas, Two Crows, Amargosa Playa, and t h e Chambers Mine respectively.

The f l u o r i n e analyses were done by J. Thomas, Jr.,

Geological Survey.

I l l i n o i s State

The B a l l a r a t s a p o n i t e c o n t a i n s even l e s s F- than t h e sepio-

l i t e formed i n an a l l u v i a l t e r r a c e i n N o r t h Las Vegas, b u t m r e F- than t h e saponite c l a y c o n t a i n s (242 ppm) i n which i t commonly occurs.

166

CONCLUSIONS 1.

The B a l l a r a t s e p i o l i t e appears t o have been formed by a l t e r a t i o n o f

p r e v i o u s l y e x i s t i n g m i n e r a l s , p r i m a r i l y s a p o n i t e , r a t h e r t h a n by d i r e c t c r y s t a l l i z a t i o n as were f o u r nearby s e p i o l i t e d e p o s i t s p r e v i o u s l y d e s c r i b e d (Post, 1978).

The s e p i o l i t e formed as c o a t i n g s on t h e s u r f a c e s o f leached

f r a c t u r e zones i n metamorphosed l i m e s t o n e which was i n t e r m i t t e n t l y covered by a Pleistocene lake. 2.

The d i f f r a c t i o n peaks f o r s e p i o l i t e specimens a r e n o t always w e l l de-

f i n e d s o t h a t t h e r e a r e v a r i a t i o n s i n observed d i f f r a c t i o n p a t t e r n s o f s e p i o l i t e specimens f r o m d i f f e r e n t sources and t h e d i f f r a c t i o n i n d i c e s o f d i f f e r e n t patterns are n o t consistent. 3.

The assignment o f i n f r a r e d v i b r a t i o n a l modes becomes d i f f i c u l t w i t h o u t

a consistent mineral s t r u c t u r e .

F u r t h e r , t h e p o s i t i o n o f t h e OH s t r e t c h i n g

bands f o r t h e f i b r o u s B a l l a r a t s e p i o l i t e specimen do n o t match t h e band p o s i t i o n s g i v e n f o r o t h e r specimens, such as t h e Kuzu s e p i o l i t e .

I n addition, both

t h e B a l l a r a t s e p i o l i t e and t h e Two Crows s e p i o l i t e show s i x more bands t h a n t h e Kuzu s e p i o l i t e (Nagata, e t a l , 1974). 4.

The e s t a b l i s h m e n t o f a r a t h e r p u r e s e p i o l i t e m i n e r a l s t a n d a r d w i l l b e

u s e f u l i n comparing s e p i o l i t e f r o m d i f f e r e n t sources and d e v e l o p i n g a c o n s i s t e n t s e p i o l i t e s t r u c t u r a l model.

For t h i s purpose Two Crows s e p i o l i t e specimens a r e

b e i n g made a v a i l a b l e through t h e s o u r c e c l a y m i n e r a l s c o l l e c t i o n o f t h e C l a y Minerals Society. REFER ENC E S Borg, I. Y. and Smith, 0. K., 1969. C a l c u l a t e d X-ray powder p a t t e r n s f o r s i l i c a t e m i n e r a l s . Geol. SOC. Am. Mem. 122:582-584. B r i n d l e y , G. W., 1980. O r d e r - d i s o r d e r i n c l a y m i n e r a l s t r u c t u r e s , Ch. 2:186-188. I n G. 1.1. E r i n d l e y and G. Brown ( E d i t o r s ) , C r y s t a l S t r u c t u r e s o f C l a y M i n e r a l s and t h e i r X-ray I d e n t i f i c a t i o n . M i n e r a l S o c i e t y , London. C a i l l e r e , S. and Henin, S., 1961. S e p i o l i t e , Ch. 8:325-342. I n G. Brown ( E d i t o r ) , The X-ray I d e n t i f i c a t i o n and C r y s t a l S t r u c t u r e s o f C l a y M i n e r a l s . M i n e r a l o g i c a l S o c i e t y , London. C a i l l e r e , S. and Henin, S., 1957. The S e p i o l i t e and p a l y g o r s k i t e m i n e r a l s , Ch. 9:231-247. I n R. C. Mackenzie ( E d i t o r ) , The D i f f e r e n t i a l Thermal I n v e s t i g a t i o n o f Clays, M i n e r a l o g i c a l S o c i e t y , London. D r o s t e , J. B., 1961. C l a y m i n e r a l s i n sediments o f Owens, China, S e a r l e s , Panamint, B r i s t o l , Cadiz, and Danby Lakes, C a l i f o r n i a . Geol. SOC. Am. B u l l . 72:1713-1721. Farmer, V. C., 1958. The i n f r a r e d s p e c t r a o f t a l c , s a p o n i t e , and h e c t o r i t e . Min. Mag. 31:829-845. Hayashi, H., Otuska, R. and I m a i , N., 1969. I n f r a r e d s t u d y o f s e p i o l i t e and p a l y g o r s k i t e on h e a t i n g . Am. Min. 54-1613-1624. Labotka, T. C., 1978. Geology o f t h e Telescope Peak Quadrangle, C a l i f o r n i a , and t h e L a t e Mesozoic r e g i o n a l metamorphism, Death V a l l e y area, C a l i f o r n i a . Ph.D. t h e s i s (unpubl;). C a l i f o r n i a I n s t i t u t e o f Technology, Pasadena, C a l i f o r n i a , 352 pp. S p r i n g e r V e r l a g , N.Y., M i l l o t , G., 1970. Geology o f Clays, Ch. 6:169-174. 400 pp.

167

Murphy, F. PI., 1932. Geology o f a p a r t o f t h e Panamint Range, C a l i f o r n i a . R e p o r t 28 o f t h e S t a t e t l i n e r a l o g i s t , M i n i n g i n C a l i f o r n i a 28:329-376. Nagata, H., Shimoda, S. and Sudo, T., 1974. On d e h y d r a t i o n o f bound w a t e r o f s e p i o l i t e . Clays and Clay M i n e r a l s 22:285-293. Neal, J . T. ( E d i t o r ) , 1975. Playas and D r i e d Lakes. Benchmark Papers i n Geology 20, H a l s t e a d Press, 411 pp. Otsuka, R., Hayashi H. and Shimoda, S., 1968. I n f r a r e d a b s o r p t i o n s p e c t r a o f s e p i o l i t e and p a l y g o r s k i t e : Flemoirs o f t h e School o f S c i e n c e and E n g i n e e r i n g , blaseda U n i v e r s i t y , 32, 13-24. Post, J . L . , 1978. S e p i o l i t e d e p o s i t s o f t h e Las Vegas, Nevada, area. Clays and C l a y M i n e r a l s 26:58-64. Post, J . L . , 1981. Volume change and expansion p r e s s u r e o f s m e c t i t e s . C a l i f o r n i a Geology 34:197-203. Smith, R. S. U., 1976. L a t e q u a t e r n a r y p l u v i a l and t e c t o n i c h i s t o r y of Panamint V a l l e y , I n y o and San B e r n a r d i n o C o u n t i e s , C a l i f o r n i a . Ph.D. t h e s i s (unpubl.) C a l i f o r n i a I n s t i t u t e o f Technology, Pasadena, C a l i f o r n i a , 295 pp. Velde, B., 1977. Clays and Clay M i n e r a l s i n N a t u r a l and S y n t h e t i c Systems. E l s e v i e r , N.Y. 140-156. Weaver, C.E. and P o l l a r d , L. D., 1973. The Chemistry o f Clay M i n e r a l s . E l s e v i e r , N.Y. 127-130.

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169

PEDOGENIC PALYGORSKITE IN THE ARID ENVIRONMENT *

ARIEH SINGER The Seagram Centre f o r S o i l and Water Sciences, The F a c u l t y of A g r i c u l t u r e , The Hebrew U n i v e r s i t y o f Jerusalem. ABSTRACT

:

Pedogenic p a l y g o r s k i t e occurrences a r e reviewed. commonly a s s o c i a t e d with e i t h e r : a .

Pedogenic p a l y g o r s k i t e i s

modern s o i l s t h a t a r e a t p r e s e n t or have

i n t h e p a s t been a f f e c t e d by r i s i n g ground water; b . s o i l formations t h a t include d i s t i n c t and sharp t e x t u r a l t r a n s i t i o n s , such a s many p a l e o s o l s ; c. pedogenic f e a t u r e s , such a s c a l c r e t e s , c r u s t s and c a l i c h e s .

Each one o f

t h e s e s p e c i f i c pedological o r geomorphological s e t t i n g s , i n a s s o c i a t i o n with an a r i d environment, can a p p a r e n t l y s a t i s f y t h e t h r e s h o l d concentration r e q u i r e ments f o r p a l y g o r s k i t e s t a b i l i t y .

The pedogenesis of p a l y g o r s k i t e i n t h e s e

formations appears t h e r e f o r e t o b e a l t o g e t h e r f e a s i b l e , as f a r as requirements of t h e s o l u t i o n chemistry are concerned. INTRODUCTION P a l y g o r s k i t e i s a common c l a y mineral i n t h e a r i d environment.

I t has been

reported from many c o u n t r i e s i n t h e Near and Middle E a s t , from northern and southern A f r i c a , n o r t h e r n and C e n t r a l America, A u s t r a l i a and even Europe.

Yet,

s i n c e t h e major X-ray r e f l e c t i o n used f o r t h e cursory i d e n t i f i c a t i o n of p a l y g o r s k i t e is l i k e l y t o be masked by t h a t of i l l i t e , a common c l a y mineral i n a r i d s o i l s , and s i n c e p a l y g o r s k i t e i s very r a r e l y a dominant c l a y mineral i n t h e c l a y f r a c t i o n s of t h e s e s o i l s , it has been considered r e l a t i v e l y r a r e . I n t o many of t h e s e s o i l s , p a l y g o r s k i t e has been passed over from t h e sedimentary p a r e n t m a t e r i a l . i n these s o i l s .

Under a r i d c o n d i t i o n s , t h e mineral w i l l then p e r s i s t

When t h e c l i m a t e i s more humid, t h e mineral w i l l gradually

d i s i n t e g r a t e and d i s a p p e a r , as r e c e n t l y shown by Bigham e t a l . (1980) f o r

s o i l s developed on Texas High P l a i n sediments.

In many o t h e r s o i l s , however,

t h e r e i s no evidence f o r t h e p a l y g o r s k i t e having been i n h e r i t e d from t h e parent material.

Moreover, modern SEM techniques suggest t h a t i n t h e s e s o i l s

p a l y g o r s k i t e had formed i n t h e s o i l environment and i s of pedogenic o r i g i n .

P r e s e n t e d a t t h e I n t e r n a t i o n a l Clay Conference

1981.

170

ENVIRONMENTS OF PEDOGENIC PALYGORSKITE While small amounts of p o s s i b l y pedogenic p a l y g o r s k i t e can be i d e n t i f i e d i n a wide v a r i e t y of s o i l s , s i g n i f i c a n t amounts of t h e "in s i t u " formed mineral can commonly be a s s o c i a t e d with one of t h e t h r e e following s i t u a t i o n s : a.

Modern s o i l s t h a t a r e a t p r e s e n t , o r have i n t h e p a s t been a f f e c t e d by

r i s i n g ground water. b.

S o i l formations t h a t i n c l u d e d i s t i n c t and s h a r p t e x t u r a l t r a n s i t i o n s ;

t h i s group includes many p a l e o s o l s c.

.

Pedogenic f e a t u r e s , not n e c e s s a r i l y a s s o c i a t e d a t p r e s e n t with s o i l s ,

such a s c a l c r e t e s , c r u s t s and c a l i c h e s . Modern s o i l s a f f e c t e d by r i s i n g ground water The p r i n c i p a l s o i l types from which a u t h i g e n i c p a l y g o r s k i t e had been report e d a r e given i n Table 1. f a l l of ~ 4 0 0mm/y.

A l l a r e contemporaneous s o i l s formed under a r a i n -

The most common landscape a s s o c i a t e d with t h e s e s o i l s is

t h a t o f flood p l a i n s o r low t e r r a c e s .

S a l i n e o r a l k a l i n e ground water i s f r e -

quently a f f e c t i n g s o i l formation such a s i n t h e c a s e o f t h e sebkhas o f t h e most arid areas.

Fine-textured calcareous, a l l u v i a l o r a e o l i a n sediments a r e common

parent materials f o r these s o i l s .

The n a t i v e v e g e t a t i o n c o n s i s t s o f halomor-

p h i c p l a n t s , such a s A t r i p l e x , and d e s e r t s h r u b s .

While some of t h e s e s o i l s ,

such a s t h e Reg s o i l s , may be very o l d , most of t h e o t h e r s o i l s formed on flood p l a i n s a r e r e l a t i v e l y young, Holocene s o i l s .

Y e t i t seems t h a t only on some-

what o l d e r s o i l s , such a s those formed on low t e r r a c e s , does p a l y g o r s k i t e f o r mation become s u b s t a n t i a l (Abtahi, 1977).

An i n d i c a t i o n o f t h e age o f a paly-

g o r s k i t e - c o n t a i n i n g s o i l i s given by Lang and Pias (1971) who dated t h e c a l Crete of a brown s o i l containing p a l y g o r s k i t e i n Afghanistan a t 15.350 B . P . The most frequent t e x t u r e s a s s o c i a t e d with pedogenic p a l y g o r s k i t e a r e loamy v a r i e t i e s such a s s i l t y c l a y loams.

Though Hodge e t a l . (1983) r e p o r t paly-

g o r s k i t e s t r o n g l y combined with organic m a t t e r i n a ground water rendzina from southern A u s t r a l i a , p a l y g o r s k i t e - c o n t a i n i n g s o i l s commonly a r e poor i n organic matter.

P a l y g o r s k i t e concentrations vary somewhat with s o i l s depth, but d i s -

t i n c t p a l y g o r s k i t e accumulation horizons have not been r e p o r t e d .

Palygorskite-

containing s o i l s i n v a r i a b l y are calcareous throughout and mildly a l k a l i n e . C a l c i t e is t h e most common carbonate, though t h e Saudi Arabian T o r r i f l u v e n t s a l s o contain some dolomite (Mashhadi e t a l . , 1980).

pH vary between 7.5 and 8 .

A N a t r i x e r a l f from southern I r a n i s r e p o r t e d with a pH exceeding 8 (Abtahi,

1977).

According t o Eswaran and Barzanji (1974) maximum occurrence of paly-

g o r s k i t e i n a group o f s o i l s from I r a q was a t pH 7.9. s o i l s a r e al so highly s a l i n e .

E.C.

Palygorskite-containing

f o r t h e bottom horizons of Jordan Valley

s o i l s range between 80-100 mmhos/cm, and f o r t h e Saudi Arabian s o i l s between

171 6-280 mmhos/cm (Dan e t a l . , 1981; Mashhadi e t a l . , 1980; E l p r i n c e et a l . , 1 9 7 9 ) . In n o n - s al i n e s o i l s , p a l y g o r s k i t e ( p r o b a b ly i n h e r i t e d from t h e p a r e n t m a t e r i a l ) appears n o t t o be s t a b l e and t o d i s i n t e g r a t e o r t r a n s f o r m i n t o s m e c t i t e (Bigham e t a l . , 1980; Lee e t a l . , 1983).

C1- and S @ - are t h e p r i n c i p a l an i o n s, Ca2+ and Mg2+ t h e major c a t i o n s , e x c e p t f o r t h e s a l i n e s o i l s from so u t h er n

I r a n where Na+ and Mg2+ are t h e p r i n c i p a l c a t i o n s .

Exchangeable sodium may

re ach q u i t e h i g h v a l u e s , though o n ly t h e s o u t h e r n I r a n s o i l s a r e d i s t i n c t l y natric. Gypsum c r y s t a l s f r e q u e n t l y a r e p r e s e n t , e i t h e r throughout t h e s o i l p r o f i l e o r a t d ep t h , a d j a c e n t t o t h e p a l y g o r s k i t e o c c u r r e n c e s . P a l y g o r s k i t e f i b e r s were shown by Eswaran and B a r z a n j i (1974) t o c o a t gypsum c r y s t a l s .

The most

common c l a y m i n e r a l s t o be a s s o c i a t e d w i t h pedogenic p a l y g o r s k i t e a r e s m e c t i t e , mica and i n t e r l a y e r e d mica-smectite. S o i l s o r sediments w i t h a t e x t u r a l t r a n s i t i o n S o i l s o r l a y e r e d s e d i m e n ts t h a t c o n t a i n s h a r p t e x t u r a l t r a n s i t i o n s sometimes c o n t ai n pedogenic p a l y g o r s k i t e .

The p a l y g o r s k i t e o c c u r s a d j a c e n t t o t h e t e x -

t u r a l t r a n s i t i o n , i n t h e form of c u t a n s ( p a l yg o r sk an s) t h a t mat c o a r s e r mineral g r a i n s , o r a g g r e g a t e s t h a t f i l l v o i d s.

Occurrences o f t h i s t y p e are

t y p i c a l f o r p a l e o s o l s and have been r e p o r t e d from NSW, A u s t r a l i a ( S i n g er and N o r r i s h , 1974), a l o e s s - d e r i v e d p a l e o s o l from A u s t r i a (Schwaighofer, 1980) and an a r i d brown p a l e o s o l i n I s r a e l (Yaalon and Wieder, 1976).

p a l e o s o l c o n t a i n i n g p a l y g o r s k i t e i s r e p o r t e d by Blom (1970). s o i l s are s i t u a t e d i n a r e a s w it h r e l a t i v e l y high r a i n f a l l .

A Lower T r i a s s i c

Some of t h e s e But s i n c e t h ey are

p a l e o s o l s , p a l y g o r s k i t e f o r m a ti o n does n o t n e c e s s a r i l y r e f l e c t p r e s e n t c l i matic c o n d i t i o n s .

Most o f t h e s e s o i l s are n o n - s a l i n e o r o n l y s l i g h t l y s a l i n e .

Some of t h e s e s o i l s c o n t a i n s e c o n d a r y c a l c i t e i n t h e form o f n o d u l es. Magnesia c a l c i t e and d o lo m it e sometimes supplement c a l c i t e .

The pedogenic

p a l y g o r s k i t e o ccu r s p r i m a r i l y a d j a c e n t t o t h e secondary c a l c i t e . C a l c r e t e s , c r u s t s and c a l i c h e s I t seems t h a t pedogenic c o n d i t i o n s l e a d i n g t o c a l c a r e o u s c r u s t s development

a r e a l s o f r e q u e n t l y f a v o u r a b l e f o r p a l y g o r s k i t e " i n s i t u " f o r m at i o n . M i l l o t e t a l . , (1969) i n Morocco and Lamouroux e t a l . , (1973) i n Lebanon d e s c r i b e c h e s t n u t s o i l s or brown s o i l s w i t h p a l y g o r s k i t e below t h e c a l c a r e o u s c r u s t h o r i zo n .

I n t h e Northern T e r r i t o r y o f A u s t r a l i a a l s o pedogenic p a l y -

g o r s k i t e o ccu r s below a c a l c a r e o u s - c r u s t h o r i zo n ( Si n g er and N o r r i sh , 1974). Unlike t y p i c a l a r i d i c s o i l s , i n t h e s e s o i l s t h e solum above t h e c a l c a r e o u s c r u s t can b e i n q u i t e an advanced s t a g e o f w e at h er i n g .

I n Morocco and Lebanon

t h i s upper p a r t of t h e s o i l had been a f f e c t e d by q u i t e marked r u b e f a c t i o n .

In

172 A u s t r a l i a t h i s p a r t o f t h e solum i s a c i d and c o n t a i n s k a o l i n i t e . f e a t u r e s are n o t commonly a s s o c i a t e d w it h a r i d s o i l f o r m a t i o n .

A l l these

Even when

c a l car eo u s c r u s t s ( o r c a l i c h e o r c a l c r e t e ) a r e n o t found capped by s o i l s , t h e i r o r i g i n i s co n s i d e r e d t o be pedogenic (Dan, 1 97 7 ) .

I n t h e c a l i c h e c r u s t s cap-

pi n g cemented dune r i d g e s i n t h e c o a s t a l p l a i n o f n o r t h - w est Egypt, p al y g o r s k i t e i s a major component o f t h e c l a y f r a c t i o n (Hassouba and Shaw, 1980). Calcretes from West Texas and N e w Mexico c o n t a i n p a l y g o r s k i t e a s s o c i a t e d w i t h

secondary s i l i c a (Allen and P a s h a i, 1 9 8 1 ) .

According t o Watts (1980), who

r e c e n t l y reviewed p a l y g o r s k i t e o c c u r r e n c e s i n c a l c r e t e s , t h e pedogenesis o f t h i s m i n e r a l , as w e l l as t h a t o f s e p i o l i t e and d o l o m i t e i n K al ah ar i calcretes

i s ex p l ai n ed as r e s u l t i n g from t h e release o f Mg by high-Mg t o low-Mg c a l c i t e transformations. pH.

S i is d e r i v e d from r e p l a c i v e c a l c i t e p r e c i p i t a t i o n a t h i g h

A d o l o m i t e l im e s to n e d u r i c r u s t from C e n t r a l A l g e r i a i s r i c h i n p al y g o r -

s k i t e (Smith and Whalley, 1982).

I n te r b e d d e d w i t h it are found n o d u l es of h ar d

silicrete. Whether b e i n g d e p o s i t e d from downward moving s o l u t i o n s i n s o i l b o d i e s , o r by t h e c a p i l l a r y rise of s o l u t i o n s i n s o i l s o r sed i m en t s, (and t h e subsequent exposure o f t h e s e c r u s t s by d e n u d a t i o n ) , t h e environments o f t h o s e secondary c a r b o n at e f o r m at i o n s appear f r e q u e n t l y t o be f a v o u r a b l e f o r p a l y g o r s k i t e for m at i o n . MECHANISMS OF PEDOGENIC FORMATION Pedogenic p a l y g o r s k i t e h a s been proposed t o form ( a) by a l t e r a t i o n o f p r e c u r s o r m i n e r a l s such as smectite; (b) by p r e c i p i t a t i o n from s o l u t i o n . A l t e r a t i o n o f p r e c u r s o r m in e r a ls Although t h e a l t e r a t i o n o f smectite i n t o p a l y g o r s k i t e u n d er h i g h l y s a l i n e and a l k a l i n e c o n d i t i o n s h a s been proposed i n s o u t h e r n I r a n s o i l s (Abtahi, 1977) and q u a n t i t a t i v e p a l y g o r s k i t e / s m e c t i t e r e l a t i o n s h i p s i n t h e a r i d brown p a l e o s o l from I s r a e l (Yaalon and Wieder, 1976) and i n t h e o a s e s s o i l s o f e a s t e r n Saudi Arabia ( E l p r i n c e e t a l . , 1979), a p p e a r t o s u pp o r t t h i s p r o c e s s of t r an sf o r m at i o n , no morphological e v i d e n c e h a s been produced t o s u b s t a n t i a t e i t . I n v e r s e p a l y g o r s k i t e / s m e c t i t e q u a n t i t a t i v e r e l a t i o n s h i p s i n Texas High P l a i n s s o i l s and i n e a s t e r n Saudi Arabia have been used t o propose an i n v e r s e p a l y g o r s k i t e t o s m e c t i t e t r a n s f o r m a t i o n (Bigham e t a l . , 1980; Lee e t a l . , 1983). The s t a b i l i t y diagrams f o r p a l y g o r s k i t e / s m e c t i t e proposed by Weaver and Beck (1977) and E l p r i n c e e t a l . , (1979) s u g g e s t t h a t p a l y g o r s k i t e s t a b i l i t y i s favoured o v er t h a t o f smectite by i n c r e a s e s i n t h e a c t i v i t i e s of e i t h e r Mg, S i o r pH.

The f r e q u e n t a s s o c i a t i o n o f t h e s e two c l a y m i n e r a l s t h u s i s a r e s u l t of

t h e p r o x i m i t y i n t h e i r s t a b i l i t y f i e l d s , b u t does n o t n e c e s s a r i l y i m p l i c a t e a s o l i d phase " t r an s f o r m a ti o n " o f one i n t o a n o t h er .

P a l y g o r s k i t e f o r m at i o n by

173 t r a n s f o r m a t i o n of s m e c t i t e i s a l s o u n l i k e l y because o f t h e s i g n i f i c a n t energy requirements f o r t h e b r e a k in g o f bonds i n v o l v ed i n t h e i n v e r s i o n o f t e t r a h e d r a . P r e c i p i t a t i o n from s o l u t i o n According t o t h e e x p e r i m e n ta l r e s u l t s o f S i n g e r and N o r r i s h (1974), f o r p a l y g o r s k i t e t o be s t a b l e , c e r t a i n t h r e s h o l d v al u es o f pH, Mg and S i concent r a t i o n have t o be a t t a i n e d .

P o s s i b l y s u i t a b l e p h y s i c a l microenvironments

r e l a t i n g t o p o r e s p a c e are a l s o r e q u i r e d .

P a l y g o r s k i t e ap p ear s t o n u c l e a t e

p r e f e r e n t i a l l y on i n o r g a n i c c r y s t a l l i n e s u b s t r a t e such as sand and s i l t - s i z e d c a l c i t e o r gypsum c r y s t a l s , though c o a t i n g s o f q u a r t z , f e l d s p a r and hornblende have a l s o been r e p o r t e d .

Under s p e c i f i c p e d o l o g i c a l o r geomorphological c i r -

cumstances, t h e r e q u i r e d c o n c e n t r a t i o n s o f Mg and S i can a p p a r e n t l y b e a t t a i n e d : (a) i n s o i l s a f f e c t e d by r i s i n g ground water and su b m i t t ed t o c o n d i t i o n s of s t r o n g and continuous e v a p o r a t i o n , (b) i n s o i l s o r sed i m en t s w i t h d i s t i n c t and sh ar p t e x t u r a l t r a n s i t i o n s .

M o i s tu r e moving i n t h e s o i l , when p a s s i n g from

f i n e r t o c o a r s e r t e x t u r e d h o r iz o n s i s l i k e l y t o accumulate a t t h e boundary i n o r d e r t o a t t a i n t h e h i g h e r p r e s s u r e needed t o f i l l t h e l a r g e r p o r e s .

These

boundary h o r i z o n s are t h e r e f o r e l i k e l y t o remain s a t u r a t e d f o r l o n g er time i n t e r v a l s even under a r i d c o n d i t i o n s .

The pedogenic p a l y g o r s k i t e accumulations

a r e a s s o c i a t e d w i t h t h e s e boundary l a y e r s (Yaalon and Wieder, 1 9 7 6 ) . Where p a l y g o r s k i t e c o e x i s t s w i t h s e c o n d a r y d o l o m i t e, such as i n t h e p a l e o s o l on l o e s s from A u s t r a l i a , i n t h e modern s o i l from Saudi Arabia and i n many o f t h e d o l o m i t e c a l c r e t e o c c u r r e n c e s , s o l u b l e Mg c o n c e n t r a t i o n s have e v i d e n t l y been ad eq u at e f o r p a l y g o r s k i t e f o r m a t io n .

I n many o t h e r o ccu r r en ces, t h e con-

ve r s i o n o f high-magnesium c a l c i t e i n t o low-magnesium c a l c i t e d u r i n g c r u s t formation a p p a r e n t l y m o b il iz e s s u f f i c i e n t Mg i n t o t h e p o r e water (Hassouba and Shaw, 1980; Smith and Whalley, 1982).

Apparently i n s o i l s a f f e c t e d by r i s i n g

ground water, such as i n t h e s a l i n e sebkha s o i l s d e s c r i b e d from e a s t e r n Saudi Arabia, c o n c e n t r a t i o n s i n t h e s o i l s o l u t i o n may r e a c h as h i g h v al u es as pMg 0.69 ( E l p r i n c e e t a l . , 1979).

P r e c i p i t a t i o n o f Ca i n t h e form of gypsum may

a l s o be s i g n i f i c a n t i n r a i s i n g t h e s o l u b l e Mg a c t i v i t y . I n s p e c i f i c pedogenic environments, such as c a l c r e t e s and d u r i c r u s t s , d i s c r e t e secondary s i l i c a t e s t h a t o c c u r a d j a c e n t t o a u t h i g e n i c p a l y g o r s k i t e su g g es t t h a t s o l u b l e S i had been a v a i l a b l e a t some time o r a n o t h e r f o r p a l y g o r s k i t e f o r m at i o n .

The s o l u b l e s i l i c a may have been r e l e a s e d from s i l i c a t e

mi n er al s by replacement w i t h c a l c i t e (Watts, 1980).

S i , possibly released

from d e t r i t a l q u a r t z and s i l i c a t e s , may have su b seq u en t l y d e p o s i t e d by evapor a t i o n o r m i g r a t i o n i n t o areas o f h i g h e r s a l i n i t y o r lower pH, s o as t o form

s i l i c r e t e w i t h i n t h e j o i n t s o f a d o lo m it e l i m e s t o n e i n A l g e r i a (Smith and Whalley, 1982).

Some o f t h i s s o l u b l e S i may have s u f f i c i e n t l y r a i s e d S i

a c t i v i t i e s f o r p a l y g o r s k i t e p r e c i p i t a t i o n w i t h i n t h e p o r e s and channels o f t h e

174 dolomite limestone.

Secondary s i l i c a t e s i n a s s o c i a t i o n w i t h pedogenic p a l y -

g o r s k i t e have n o t been r e p o r t e d from a r i d s o i l s and would a l s o b e d i f f i c u l t t o identify.

Many a u t h o r s , such as Wiersma (1970), t h e r e f o r e b e l i e v e t h a t t h e

m o b i l i t y o f S i u n d e r a r i d c o n d i t i o n s i s t o o low t o e x p l a i n t h e l a r g e amounts o f S i required f o r p a l y g o r s k i t e formation.

S u p e r s a t u r a t i o n r e l a t i v e t o S i is

n o t , however, r e q u i r e d f o r p a l y g o r s k i t e f o r m a t i o n .

The a v e r a g e s i l i c a c o n t e n t

of s o i l s o l u t i o n s i s r e p o r t e d t o be 15-20 ppm (Wilding e t a l . , 1 9 7 7 ) .

Accep-

t i n g t h e s e v a l u e s f o r a r i d i c s o i l s a l s o , and t a k i n g t h e Mg c o n c e n t r a t i o n s o f s o i l e x t r a c t s quoted f o r s o i l s c o n t a i n i n g pedogenic p a l y g o r s k i t e i n Saudi Arabia ( E l p r i n c e e t a l . , 1979), I s r a e l (Dan e t a l . , 1981) and i n I r a n (Abtahi, 1977), i t can b e s e e n t h a t c o n d i t i o n s f o r t h e s t a b i l i t y o f p a l y g o r s k i t e as e s t a b l i s h e d by S i n g e r and N o r r i s h (1974) are a l l met.

The pedo-

g e n e s i s o f p a l y g o r s k i t e i n t h e s e s o i l s is t h e r e f o r e a l t o g e t h e r f e a s i b l e a s f a r as r e q u i r e m e n t s o f t h e s o l u t i o n c h e m i s t r y a r e concerned. REFERENCES Abtahi, A l . , 1977. Effect o f a s a l i n e and a l k a l i n e ground water on s o i l g e n e s i s i n s e m i - a r i d s o u t h e r n I r a n . S o i l S c i . Am. J., 41: 583-588. A l l e n , 9 . L . and " a s h a i , A . , 1981. S e l e c t e d m i n e r a l o g i c a l c h a r a c t e r i s t i c s o f c a l c r e t e s i n West Texas and e a s t e r n N e w Mexico. I n t . Conf. A r i d i c S o i l s , J e r u s a l e m 1981, Abst. Bigham, J . M . , Jaynes, W.T. and A l l e n , B . L . , 1980. Pedogenic d e g r a d a t i o n o f s e p i o l i t e and p a l y g o r s k i t e on t h e Texas High P l a i n s . S o i l S c i . SOC. Am. J . , 44: 159-167. Blom, G . I . , 1970. Buried p a l y g o r s k i t e s o i l s i n t h e Lower T r i a s s i c of t h e Moscow s i n e c l i n e . Dokl. ( P r o c . ) Acad. S c i . U.S.S.R. E a r t h - S c i . S e c . 194: 52-54. Dan, J., 1977. The d i s t r i b u t i o n and o r i g i n of Nari and o t h e r lime c r u s t s i n I s r a e l . I s r a e l J . E a r t h S c i . , 26: 68-83. Dan, J., Gerson, R . , Koyumdjisky, Hanna and Yaalon, D . H . , 1981. A r i d i c S o i l s o f I s r a e l . ARO, Bet Dagan, S p e c i a l P u b l i c a t i o n No. 190, 353 pp. E l p r i n c e , A . M . , Mashhady, A.S. and Aba-Husayn, M . M . , 1979. The o c c u r r e n c e o f pedogenic p a l y g o r s k i t e ( a t t a p u l g i t e ) i n Saudi A r a b i a . S o i l S c i . , 1 2 8 : 211-218. Eswaran, H . and B a r z a n j i , A . F . , 1974. Evidence f o r t h e neoformation o f a t t a p u l g i t e i n some s o i l s o f I r a q . 1 0 t h Cong. I n t . SOC. S o i l S c i . , Moscow, 7: 154-160. Hassouba, H . and Shaw, H . F . , 1980. The o c c u r r e n c e o f p a l y g o r s k i t e i n Q u a t e r n a r y s e d i m e n t s o f t h e c o a s t a l p l a i n o f n o r t h - w e s t Egypt. Clay M i n e r a l s , 15: 77-83. Hodge, T . , Turchenek, L.W. and Oades, J . M . , 1983. Occurrence o f p a l y g o r s k i t e i n ground water r e n d z i n a s ( P e t r o c a l c i c c a l c i a q u o l l s ) i n s o u t h - e a s t South A u s t r a l i a . This volume. Hutton, J . T . and Dixon, J . C . , 1981. The c h e m i s t r y and mineralogy o f some S.A. c a l c r e t e s and a s s o c i a t e d s o f t c a r b o n a t e s and t h e i r d o l o m i t i z a t i o n . J . Geol. SOC. A u s t r . , 28: 71-79. Lamouroux, M . , Paquet, H . e t M i l l o t , G . , 1973. E v o l u t i o n d e s mineraux a r g i l e u x dans l e s s o l s du Liban. P e d o l o g i e (Gand). 23: 53-71. Lang, J . and P i a s , J., 1971. Morphgenese "dunaire" e t pedogenese dans l e b a s s i n intramontagneux d e Bamian (Afghanistan C e n t r a l ) . Revue Geogr. phys. Geol. d y n . , 13: 359-367.

175 Lee, S.Y., Dixon, J . B . and Aba-Husayn, M . M . , 1983. Mineralogy o f Saudi Arabian S o i l s : E a s t e r n Region. S o i l S c i . SOC. Am. J . , 47: 321-326. Mashhady, A.S., Reda, M . , Wilson, M . J . and Mackenzie, R . C . , 1980. Clay and s i l t mineralogy o f some s o i l s from Qasim, Saudi A r a b i a . J . S o i l S c i . , 31: 101-115 M i l l o t , G . , Paquet, H . , e t R u e l l e n , A , , 1969. Neoformation d e l ' a t t a p u l g i t e dans les s o l s a c a r a p a c e s c a l c a i r e s d e l a b a s s e Moulouya (Maroc o r i e n t a l ) C . R . Acad. S c i . , P a r i s , 268: 2771-2774. Schwaighofer, B . , 1980. P e d o g e n e t i s c h e r P a l y g o r s k i t i n einem L o s s p r o f i l b e i S t i l l f r i e d an d e r March ( N i e d e r o s t e r r e i c h ) . Clay M i n e r a l s , 1 5 : 283-289. S i n g e r , A . and N o r r i s h , K . , 1974. Pedogenic p a l y g o r s k i t e o c c u r r e n c e s i n A u s t r a l i a . Am. M i n e r a l . , 59: 508-517. Smith, B . J . and Whalley, W . B . , 1982. O b s e r v a t i o n s on t h e composition and m i n e r a l o g y . o f an A l g e r i a n d u r i c r u s t complex. Geoderma, 28: 285-311. Watts, N . L . , 1980. Q u a t e r n a r y pedogenic c a l c r e t e s from t h e K a l a h a r i (South A f r i c a ) : mineralogy, g e n e s i s and d i a g e n e s i s . Sedimentology, 27: 661-686. Weaver, C . E . and Beck, K . C . , 1977. Miocene of t h e S.E. United S t a t e s : a model f o r chemical s e d i m e n t a t i o n i n a p e r i - m a r i n e environment. Sediment. G e o l . , 17: 1-234. Wiersma, J . , 1970. Provenance, g e n e s i s , and p a l e o g e o g r a p h i c a l i m p l i c a t i o n s o f microminerals o c c u r r i n g i n s e d i m e n t a r y r o c k s o f t h e J o r d a n V a l l e y area. Phys. Geogr. S o i l S c i . Lab., Univ. Amsterdam, 15, 240 p p . Wilding, L . P . , Smeck, N . E . and Drees, L . R . , 1977. S i l i c a i n s o i l s . I n : J . B . Dixon and S.B. Weed ( E d i t o r s ) , M i n e r a l s i n S o i l Environments, S o i l S c i . SOC. A m . , Madison, Wisconsin, 471-552 p p . Yaalon, D . H . and Wieder, M . , 1976. Pedogenic p a l y g o r s k i t e i n some a r i d brown ( c a l c i o r t h i d ) s o i l s o f I s r a e l . Clay M i n e r a l s , 1 1 : 73-80.

176

TABLE 1 Occurrences o f pedogenic p a l y g o r s k i t e i n t h e a r i d environment.

Formation

Formative element

Locality

Reference

A l l u v i a l Solonchak

Rising ground water

Jordan Valley, Israel Southern I r a n

Dan e t a l . , 1981 Abtahi, 1977

Saudi Arabia

Mashhady e t a l . , 1980

Iraq South A u s t r a l i a East Saudi Arabia Southern I s r a e l

Eswaran 6 Barzanji, 1974 Hodge e t a l . , 1983 E l p r i n c e e t a l . , 1979 Yaalon & Wieder, 1976

NSW, A u s t r a l i a Austria Soviet Union Morocco

S i n g e r 6 Norrish, 1974 Schwaighofer, 1980 B l o m , 1970 M i l l o t e t a l . , 1969

Lebanon NT. A u s t r a l i a Texas, N. Mexico, u . S . A . S . Australia NW-Egypt Afghanistan South A f r i c a Algeria

Lamouroux e t a l . , 1973 Singer 6 Norrish, 1974 Allen & Pashai, 1981

Salorthid, Natrixeralf Torriorthent , Salorthid Gypsiorthid, Torriorthent Ground water Rendzina Sebkha s o i l Arid brown p a l e o s o l Red Earth p a l e o s o l Paleosol on l o e s s Paleosol Chestnut s o i l s Brown s o i l Calcareous Red Earth Calcrete Calcrete Caliche Calcrete C a l c r et e Duricrust ( c a l c r e t e )

I,

II

II

I1

Textural t r a n s i t ion II II 11

Calcareous crust II 11

I1

Hutton & Dixon, 1981 Hassouba & Shaw, 1980 Lang & P i a s , 1971 Watts, 1980 Smith & Whalley, 1982

177

O R I G I N OF PALYGORSKITE I N SOME SOILS OF THE ARABIAN PENINSULA*

R.C.

MACKENZIE*, M;J.

WILSON* and A.S.

MASHHADYt

*

The Macaulay I n s t i t u t e f o r S o i l Research, C r a i g i e b u c k l e r , Aberdeen, Scotland, UK. t S o i l Department, F a c u l t y o f A g r i c u l t u r e , King Saud U n i v e r s i t y , Riyadh, Saudi A r a b i a .

ABSTRACT E x a m i n a t i o n o f s o i l c l a y s f r o m Saudi A r a b i a and t h e P e o p l e ' s R e p u b l i c o f t h e South Yemen by X-ray d i f f r a c t i o n , DTA and e l e c t r o n m i c r o s c o p y has shown t h e widespread o c c u r r e n c e o f p a l y g o r s k i t e .

D e t a i 1ed e x a m i n a t i o n o f wadi samples

suggest t h a t b o t h n e o f o r m a t i o n and i n h e r i t a n c e a r e o p e r a t i v e , t h e f o r m e r predominating.

S e p i o l i t e was f o u n d i n a wadi sample and v e r m i c u l i t e i n mountain

and d e l t a samples f r o m Yemen.

The s i g n i f i c a n c e i s discussed.

INTRODUCTION

A t one t i m e p a l y g o r s k i t e was c o n s i d e r e d a r e l a t i v e l y r a r e m i n e r a l i n s o i l s , b u t s i n c e t h e e a r l y 1960s a n i n c r e a s i n g number o f r e p o r t s o f i t s o c c u r r e n c e have appeared

-

p a r t i c u l a r l y i n s o i l s o f a r i d r e g i o n s ( Z a l a z n y and Calhoun,

1977).

Although E l g a b a l y (1962) envisaged i t s in sit^ f o r m a t i o n f r o m c a l c a r e o u s a r g i l l a c e o u s m a t e r i a l i n a s a l i n e lagoon, i t s o r i g i n has g e n e r a l l y been a t t r i b u t e d t o i n h e r i t a n c e from palygorskite-bearing parent m a t e r i a l s . E a r l y s t u d i e s o f A r a b i a n s o i l s tended t o s u p p o r t t h e l a t t e r v i e w (Jenkins,

1976;

Aba-Husayn and Sayegh, 1977), b u t E l p r i n c e et al. (1979) l a t e r a t t r i b u t e d a pedogenic o r i g i n t o t h e same p a l y g o r s k i t e on t h e b a s i s o f t h e o c c u r r e n c e of t h i s m i n e r a l i n s o i l s d e r i v e d f r o m a v a r i e t y o f g e o l o g i c a l m a t e r i a l s and t h e f a c t t h a t t h e composition o f t h e s o i l s a t u r a t i o n e x t r a c t s f e l l w i t h i n t h e s t a b i l i t y f i e l d o f the mineral. Abundant p a l y g o r s k i t e was a l s o f o u n d i n t h e s o i l s o f t h e l o w e r p a r t o f t h e Wadi-ar-Rimah

i n t h e Qasim a r e a (Mashhady et a l . , 1980), where t h e m i n e r a l was

c o n s i d e r e d t o be formed in situ, d i s t i n c t i o n between sedimentary and pedogenic processes b e i n g d i f f i c u l t i n such a r i d r e g i o n s .

However, an, a t l e a s t p a r t l y ,

i n h e r i t e d o r i g i n c o u l d n o t b e c o m p l e t e l y excluded, s i n c e t h e c l a y f r a c t i o n o f t h e Khuff l i m e s t o n e exposed a l o n g t h e s i d e s of t h e wadi c o n t a i n e d w e l l c r y s t a l 1 ized pa 1y g o r s k i t e . I n o r d e r t o o b t a i n more i n f o r m a t i o n on t h i s p o i n t , s o i l p r o f i l e s from t h e upper reaches o f t h e wadi t o g e t h e r w i t h t h e a d j a c e n t igneous o r metamorphic

*

Presented a t t h e I n t e r n a t i o n a l C l a y Conference 1981

178

rocks were sampled and studied.

Clay mineralogical information on some wadi

and d e l t a s o i l s o f the People's Democratic Republic of Yemen h e l p t o supplement t h e sparse information a v a i l a b l e f o r t h e Arabian Peninsula as a whole. EXPERIMENTAL Locations and S o i l s The general l o c a t i o n o f the s o i l s studied i s shown i n Fig. 1.

The m a j o r i t y

came from the Wadi-ar-Rimah area i n Qasim, t h e s o l i d geology o f which has already been described (Mashhady et a l . , 1980). The eastern p a r t o f t h i s area consists o f a series of shales, sandstones and limestones o f Cambro-Ordovician t o Jurassic age dipping g e n t l y towards t h e east and l y i n g unconformably over a Pre-Cambrian basement c o n s i s t i n g o f gneiss, micaceous s c h i s t s and p h y l l i t e s w i t h g r a n i t e i n t r u s i o n s , exposed i n t h e west.

Fig. 1.

Map o f Arabian peninsula showing l o c a t i o n s of p r o f i l e s studied.

Three s o i l p r o f i l e s were sampled from t h e main and s i d e wadis where these c u t across the Pre-Cambrian basement, one ( p r o f i l e SA 70) being i n a gneissic area and two ( p r o f i l e s SA 77 and SA 79) i n areas where micaceous s c h i s t s predominate. A f u r t h e r two came from t h e lower reaches of t h e wadi, one where the adjacent rock was Permo-Triassic Khuff limestone ( p r o f i l e SA 57) and the other (SA 55) from the Cambro-Ordovician sandstone area. Apart from P r o f i l e SA 55, which was

179

a S a l o r t h i d on wadi material, a l l t h e s o i l s were T o r r i f l u v e n t s . Basic s o i l information i s given i n Table 1 along w i t h t h a t f o r the South Yemeni samples, which o r i g i n a t e d from 3 areas: (a) t h e Abyan delta, an a g r i c u l t u r a l area where the s o i l s are developed on d e l t a i c sediments derived from weathered g r a n i t e s and b a s a l t s t o the north; ( b ) the Wadi Hadramout where t h e s o i l s are derived from limestones i n the surrounding h i l l s and plateaux; :c) Moukairas, a mountainous r e g i o n w i t h Pre-Cambrian basement rocks and w i t h a g r i c u l t u r a l l y c u l t i v a t e d land a t about 2500 m elevation. TABLE 1 Basic data f o r s o i l s from t h e Arabian Peninsula Mechani ca 1 Ana 1ys is o r Texture P r o f i l e No. or Location SA 55

SA 57

SA 70

SA 77

SA 79

Depth cm

E.C. m-mhos/cm (25°C)

CaCO, %

Sand

pH

x

Silt %

Clay %

0-10 10-70 70-100 15-55 55-100

166.6 75.5 38.3

8.0 8.2 8.2

17.2 20.5 22.5

29.7 7.2 11.5

33.7 27.5 23.4

36.6 65.3 65.1

34 .8 38.2

17.5 21.5

35.3 61.3

6 .O 3.3 2.0 1.4 0.9 0.7 3.2

4.0 6.8 8.3 14.5 10.1 8.8 7.1 4.9 8.2

47.2 17.2

0-10 10-40 40-55 55-75 75-90 90-100 1oo+ 0-35 35-45 45-70 70-1 30 130+ 10-30 30-60 60-90

8.5 8.4 8.6 8.6 8.4 8.5 8.5 8.4 8.0

55.5 39.7 48.3 59.9 72.3 80.7 59.7

13.4 23.8 24.7 11.6 9.7 2.8 9.8

31.1 36.5 27.0 28.5 18.0 16.5 30.5

7.7 8.0 7.8 7.9 7.7 8.2 8.2 8.9 7.7 8.3 8.0 7.7

7.5 6.0 10.6 13.3 10.9 4.3 7.7 7.7 45.0 15.0 12.0 12.0

64.2 82.2 46.2 35.2 45.5 67.5 70.2 66.2

9.6 1.6 16.6 25.6 22.7 17.7 17.6 11.6

26.2 16.2 37.2 39.2 31.8 14.8 12.2 22.2

Wadi Hadramout Abyan D e l t a (S.E.)* Abyan D e l t a (Centre) Moukairas

32.8 14.2 33.3 18.6 56.9 44.6 30.3 12.7 5.5 0.8 1.5 2.6

Sandy loam Clay loam Sandy loam Sandy loam

~~~

*

Three samples from t h i s area were s i m i l a r : r e s u l t s a r e therefore meaned i n Tables 1 and 2.

Methods The S o i l s were dispersed i n water, washed f r e e from s a l t and t h e c l a y (<2 f r a c t i o n separated by sedlmentation.

pm)

180

X-ray d i f f r a c t i o n was performed w i t h a P h i l i p s 1130/90 2 kW d i f f r a c t o m e t e r using CoKa r a d i a t i o n . Oriented aggregates o f c l a y f r a c t i o n s were prepared by drying down some suspension on a glass s l i d e . D i f f r a c t i o n p a t t e r n s were obtained before and a f t e r g l y c e r o l treatment and a f t e r heating a t 300°C f o r Where the occurrence o f v e r m i c u l i t e was suspected, selected samples

2 hours.

were pre-saturated w i t h Mga+ before g l y c e r o l treatment and w i t h K+ before heating.

Q u a n t i t a t i v e r e s u l t s f o r the Wadi-ar-Rimah samples were obtained

using the method of Chung (1974), whereby a selected r e f l e c t i o n from each mineral i s assigned a k i f a c t o r r e l a t i n g " i t s i n t e n s i t y t o t h a t o f a r e f l e c t i o n TABLE 2

Mineralogy of s o i l clays from the Arabian Peninsula P r o f i l e No. or Location

SA 55

SA 57

P

Sep

K

Sm

V

M

Ch Q

Ca

F

0-10 10-70 70-100

20 25 20

-

15 30 10 10 10 10

-

-

25 25

5 10 10 20 15 20 5 5 10 10 10

-

15-55 55-100

15 15 10 15 15 15 20 15 15

Depth

SA 70

0-10 10-40 55-75 100+

35 40 40 35

SA 77

0-35 35-45 45-70 70-130 130+

35 30 35 30 35

10-30 30-60 60-90 Wadi Hadramout Abyan D e l t a (S.E.) Abyan Delta (Centre) Mouk a i r a s

20 30 30

SA 79

&: P

-

-

-

-

-

-

++++ tr

10 15 10 15 10 10 10 10 10 15

-

-

-

-

-

t r +

+++

+

-

5 5 5

20 5 10

+++ +

-

+ +

+ t

-

+

+

tr

-

-

tr 5

t r -

15 25 30

tr

-

t r -

10 5 5 10 10 10 10 10 10 5

+

-

+

5 5 5 5 5

+

-

- - -

++ + -

20 20 20 15 15

- -

G

+ +

10 10 10 10 10 10 10 15

+

-

-

5

H

- - -- -- - - - - - - - - - - tr - - -

10 5 5 5

-

+

-

-

-

10 25 20

5 5 5

-

+

+

10 40 15 10 10 5 5 10 10 5 10 10

5 5 5

Cr

5 -

-

5 tr - 5 - tr - 5 tr - tr 10 tr 5 25

-

-

+++

-

-

tr tr

palygorskite; Sep s e p i o l i t e ; K - k a o l i n i t e ; Sm smectite; V vermiculite; M mica; Ch c h l o r i t e ; Ca calcite; F feldspar; Cr cristobalite; Q quartz; H - hornblende; G - goethite: a l l figures a r e percentages. +++ Dominant; ++ abundant; + subordinate; tr trace; n o t detected.

-

-

-

-

-

-

-

-

from a reference mineral i n a 50:50 mixture.

The reference m a t e r i a l chosen

f o r non-clay minerals was corundum ( r e f l e c t i o n a t 2 . 0 d ) and f o r c l a y minerals boehmite (6.11A r e f l e c t i o n ) .

I n n a t u r a l samples i t i s very d i f f i c u l t , i f not

impossible, t o determine t h e k i f a c t o r f o r a l l mineral c o n s t i t u e n t s , as t h i s

181

r e q u i r e s t h e i r a v a i l a b i l i t y i n , p u r e form

-

a requ rement almost impossible t o

s a t i s f y , as d i f f r a c t i o n p a t t e r n s o f c l a y minerals depend on c r y s t a l l i n i t y , g r a i n size, composition,

minor i n t e r s t r a t i f i c a t i o n , e t c

Thus, t h e q u a n t i t i e s f o r

c l a y m i n e r a l s can be taken o n l y as a rough approximation and, although r e s u l t s f o r non-clay m i n e r a l s a r e much more r e l i a b l e , t h e r e s u l t s as a whole merely i n d i c a t e general t r e n d s w i t h i n and between p r o f i l e s .

This technique was n o t

a p p l i e d t o t h e South Yemeni samples: consequently, r e s u l t s f o r these g i v e a general impression o f m i n e r a l abundance only. D i f f e r e n t i a 3 thermal a n a l y s i s was c a r r i e d o u t on a Stone DTA apparatus u s i n g

a post-type specimen h o l d e r and a f l o w i n g n i t r o g e n atmosphere. e l e c t r o n microscopy was performed on a Siemens 102 instrument.

Transmission

RESULTS The mineralogy o f a l l t h e Wadi-ar-Rimah s o i l s , as deduced from X-ray and DTA data, i s s i m i l a r i r r e s p e c t i v e o f t h e n a t u r e o f t h e surrounding country rock (Table 2).

The dominant m i n e r a l s a r e p a l y g o r s k i t e and/or smectite; appreciable

amounts o f k a o l i n i t e , mica, c h l o r i t e and some non-clay m i n e r a l s a l s o appear. The n a t u r e o f t h e p o o r l y ordered s m e c t i t i c component deserves some comment. When i t i s present i n l a r g e amounts, g l y c e r o l - s a t u r a t e d samples y i e l d a broad r e f l e c t i o n a t about 17.7A ( F i g . Za), b u t i n many instances o n l y a very diffuse e f f e c t between 14 and 188, w i t h no d e f i n i t e maximum, can be detected ( F i g . 2b). This almost c e r t a i n l y i n d i c a t e s i n t e r s t r a t i f i c a t i o n o f some s o r t and, although the exact n a t u r e o f t h e o t h e r component i s uncertain, mica.

i t seems l i k e l y t o be

The k a o l i n i t e a l s o appears t o be r a t h e r p o o r l y ordered.

Despite t h e broad s i m i l a r i t y i n mineralogy, some q u a n t i t a t i v e d i f f e r e n c e s can be observed.

Thus, p a l y g o r s k i t e and mica seem t o be most abundant i n the

upper reaches o f t h e wadi ( p r o f i l e s SA 70, SA 77 and SA 79, Table 2), where t h e surrounding rocks a r e igneous o r metamorphic I n character.

On t h e o t h e r hand,

l a r g e r amounts o f s m e c t i t e and k a o l i n i t e tend t o occur i n t h e lower p a r t of t h e wadi which i s f l a n k e d by sedimentary rocks.

Clay mineral d i s t r i b u t i o n w i t h i n

i n d i v i d u a l p r o f i l e s e i t h e r remains r e l a t i v e l y steady o r f l u c t u a t e s e r r a t i c a l l y . The DTA curves f o r t h e c l a y s from t h e S a l o r t h i d ( p r o f i l e SA 55) a r e c h a r a c t e r i z e d by t h e r e a c t i o n between c a l c i t e , smectite-mica and s o l u b l e s a l t s p r e v i o u s l y noted by Mashhady et ai. (1980). The mineralogy o f t h e Yemeni s o i l c l a y s i s somewhat s i m i l a r t o t h a t of those from Saudi Arabia, although t h e r e a r e differences

i n detail.

Thus, p a l y g o r s k i t e

occurs widely, being predominant i n t h e s o i l from Wadi Hadramout b u t subordinate i n the s o i l s from t h e Abyan D e l t a and Mukairas (Table 2).

The

d e l t a i c s o i l s a r e very s m e c t i t i c , t h e smectite behaving i n a manner s i m i l a r t o t h a t described above: feldspar a l s o tends t o be h i g h i n t h e Delta.

Vermiculfte

182

occurs i n one o f t h e Abyan D e l t a s o i l s and i n t h e Mukairas s o i l and a small amount o f s e p i o l i t e was-detected i n the Wadi Hadramout s o i l . DISCUSSION

C l e a r l y t h e r e i s l i t t l e r e l a t i o n s h i p between t h e occurrence of p a l y g o r s k i t e and the geological nature of the environment, since i t i s found i n wadi m a t e r i a l derived from igneous, metamorphic and sedimentary rocks and must t h e r e f o r e have formed i n situ. Furthermore, from i t s appearance i n wadi, d e l t a and mountain s o i l s i n the South Yemen, i t i s e v i d e n t l y o f very widespread occurrence over the

x)-y)

30-60

55-77

13.3

0 0

35

30

25

20

15

I0

5 I

158

Fig. 2. X-ray d i f f r a c t i o n patterns f o r g l y c e r o l - t r e a t e d s o i l clays from (a) p r o f i l e SA 79; (b) p r o f i l e SA 70. whole Arabian peninsula.

The l a r g e amounts of mica i n p r o f i l e s from t h e area

where the Wadi-ar-Rimah passes through mica s c h i s t s and the presence of p a l y g o r s k i t e i n sediments c u t through by t h e Wadi (Mashhady, et a l . , 1980)

183

i n d i c a t e s , however, t h a t i n h e r i t a n c e c a n n o t e n t i r e l y be excluded; n e v e r t h e l e s s , in situ f o r m a t i o n would appear t o be dominant.

The v i r t u a l l y compensatory p a l y g o r s k i t e - s m e c t i t e r e l a t i o n s h i p observed i n so many o f t h e s e c l a y s i s p a r t i c u l a r l y i n t e r e s t i n g and c a n be f a i r l y r e a d i l y explained, s i n c e t h e c o m p o s i t i o n a l f i e l d s o f p a l y g o r s k i t e and m o n t m o r i l l o n i t e p o s s i b l y o v e r l a p ( F i g . 3)(Mackenzie, u n p u b l i s h e d ) , a l t h o u g h p a l y g o r s k i t e tends t o be more s i l i c e o u s and t o show a w i d e r R,O,:RO

spread.

S i n g e r and N o r r i s h (1974) have shown t h a t , a t t h e c o n c e n t r a t i o n s o f s i l i c a n o r m a l l y f o u n d , i n s o i l s o l u t i o n , p a l y g o r s k i t e would n o t be s t a b l e below pH 7.7 a t h i g h magnesium c o n c e n t r a t i o n s o r below pH 9 a t l o w e r magnesium l e v e l s . Elprince

et al.

(1979) have extended t h i s approach and, w h i l e a g a i n c o n c l u d i n g

t h a t p a l y g o r s k i t e i s s t a b l e o n l y a t h i g h a c t i v i t i e s o f S i b + and Mg",

considered

t h e s t a b i l i t y o f t h e m i n e r a l i n terms o f a r e a c t i o n i n v o l v i n g s m e c t i t e .

Thus,

F i g . 3. T r i a n g u l a r diagram showing approximate c o m p o s i t i o n a l areas f o r m o n t m o r i l l o n i t e , p a l y g o r s k i t e , s a p o n i t e and s e p i o l i t e . when p a l y g o r s k i t e i s b e i n g formed, s m e c t i t e i s d i s s o l v i n g and vice versa.

This

hypothesis, w h i c h t e n d s t o be s u p p o r t e d by F i g . 3, has a l s o been proposed by Yaalon and Wieder (1976) f o r some c a l c a r e o u s a r i d brown s o i l s of t h e Negev. When t h e p r o b a b l e c o n d i t i o n s o f f o r m a t i o n a r e t a k e n i n t o account, t h e dominance o f p a l y g o r s k i t e / s m e c t i t e i n wadi d e p o s i t s i s c o n s i s t e n t w i t h t h i s concept.

C e r t a i n l y , t h e whole a r e a o f t h e Wadi-ar-Rimah

i s subject t o sporadic

p r e c i p i t a t i o n and f l o o d i n g d u r i n g t h e l a t e w i n t e r ; t h i s l e a d s t o s u r f a c e r u n - o f f o v e r s h o r t d i s t a n c e s and t o sediment d e p o s i t i o n ( A l - S a y a r i and Z o t l , 1978).

The

p e r m e a b i l i t y o f t h e sediments i s v a r i a b l e and, where p e r m e a b i l i t y i s l o w and t h e s l o p e of t h e wadi i s m i n i m a l , s h a l l o w ponds form and t h e n e v a p o r a t e t o l e a v e s a l t c r u s t s g i v i n g r i s e t o sabkhah s o i l s

- as,

f o r example, i n p r o f i l e SA 55.

Where p e r m e a b i l i t y i s b e t t e r , t h e s o i l s o l u t i o n g r a d u a l l y becomes r i c h e r i n s i l i c o n and magnesium, t h u s g i v i n g c o n d i t i o n s s u i t a b l e f o r p a l y g o r s k i t e and/or

184

smectite formation depending on the o t h e r f a c t o r s involved.

I n the d e l t a i c

s o i l s o f t h e South Yemen i t would seem t h e magnesium a c t i v i t y i s too low f o r extensive p r e c i p i t a t i o n of palygorskite, and t h e small amount present may p o s s i b l y have been washed i n from t h e wadis i n the h i n t e r l a n d . I n t h e Wadi Hadramout area, MUller (1961) has found both p a l y g o r s k i t e and s e p i o l i t e i n t h e These minerals a r e

T e r t i a r y marine limestones i n an approximate 1:l r a t i o . therefore apparently i n h e r i t e d by the fine-grained

f l u v i a t i l e sediments o f t h e

wadi, although t h e higher r a t i o o f p a l y g o r s k i t e t o s e p i o l i t e could i n d i c a t e e i t h e r in situ formation o f t h e former Qrmore r a p i d weathering o f the l a t t e r . The other minerals encountered i n t h e wadi s o i l c l a y s can be accounted f o r by d i r e c t inheritance, e i t h e r from t h e parent rocks o r from s o i l s o r deposits formed under c l i m a t i c c o n d i t i o n s v a s t l y d i f f e r e n t from t h e present. Thus, t h e

Fig. 4. Transmission e l e c t r o n micrographs o f s o i l clays from (a) P r o f i l e SA 70 and ( b ) P r o f i l e SA 79 showing w e l l developed c r y s t a l s of palygorskite. The bars i n d i c a t e 1 m. quartz, t h e feldspar and the mica ( i n p a r t , a t l e a s t ) could, according t o p e t r o l o g i c a l evidence, have come from t h e surrounding rocks, whereas t h e k a o l i n i t e and some mica may have o r i g i n a t e d i n t h e l a t e r i t i c and terra rossa

soils, remnants o f which, containing both i l l i t e and k a o l i n i t e i n t h e i r c l a y

185

f r a c t i o n s , a r e found i n some r e g i o n s o f t h e Wadi (Al-Sayari and Z6t1, 1978). The same c o n s i d e r a t i o n s presumably a p p l y t o t h e South Yemeni s o i l s , b u t t h e occurrence o f v e r m i c u l i t e i n two o f these i s i n t e r e s t i n g .

I n t h e Moukairas

sample, t h e v e r m i c u l i t e i s presumably e i t h e r i n h e r i t e d from o r formed by h y d r a t i o n o f b i o t i t e i n t h e p a r e n t rock, as i t was a l s o found by Aba-Husayn et al. (1978) i n Saudi Arabian s o i l c l a y s f u r t h e r n o r t h (near Abha,

along t h e same mountain chain. has, t h e r e f o r e ,

Fig. 1)

The v e r m i c u l i t e i n t h e c e n t r e p a r t o f t h e wadi

i n a l l p r o b a b i l i t y been washed down from t h e mountains.

Its

absence i n t h e . s o i l s on t h e south-eastern s i d e o f t h e d e l t a , and t h e presence instead of mica, may i n d i c a t e t h a t t h e m a t e r i a l i s from a d i f f e r e n t source area. I n consequence, t h e r e i s evidence i n these s o i l s o f both i n h e r i t a n c e and neoformation,

p a l y g o r s k i t e r e p r e s e n t i n g , m a i n l y a t l e a s t , neoformation.

One

i n t e r e s t i n g p o i n t observed e l e c t r o n o p t i c a l l y was t h e f a c t t h a t p a l y g o r s k i t e i n t h e Khuff l i m e s t o n e appeared as bundles o f v e r y l o n g f i b r e s , whereas t h a t from the wadi samples was more d i s p e r s e (Mashhady et ai., 1980).

Although t h e

l a t t e r o b s e r v a t i o n i s g e n e r a l l y t r u e f o r t h e samples discussed here, w e l l c r y s t a l l i z e d m a t e r i a l was observed i n p r o f i l e s SA 70 and SA 79 from an area surrounded by g n e i s s i c rocks and a p h y l l i t e area near a g r a n i t e i n t r u s i o n , respectively (Fig. 4).

It i s u n l i k e l y , therefore,

t h a t e x t e r n a l appearance can

be used t o d i s t i n g u i s h between i n h e r i t e d and neoformed m a t e r i a l . ACKNOWLEDGEMENTS The a u t h o r s wish t o thank Dr. M.A.

Abdel Salam, D i r e c t o r , Desert I n s t i t u t e ,

Cairo, f o r t h e s o i l s f r o m t h e People's Democratic Republic o f Yemen and

Dr: J.M. T a i t f o r t h e e l e c t r o n micrographs. REFERENCES Aba-Husayn, M.M. and Sayegh, A.H. (1977) Mineralogy of t h e Al-Hasa d e s e r t s o i l s (Saudi A r a b i a ) . Clays Clay Miner., 25: 138-147. Aba-Husayn, M.M., Dixon, J.B. and Lee, S.Y. (1978) Mineralogy o f Saudi Arabian soils. I. Southwestern r e g i o n . Paper d e l i v e r e d a t meeting o f S o i l Science S o c i e t y o f America, D i v i s i o n 5-9. Al-Sayari, S.S. and Z i j t l , J.G. (1978) Quaternary P e r i o d i n Saudi Arabia, Vol. 1 Springer-Verlag, Wien and New York. Chung, F.H. (1974) Q u a n t i t a t i v e i n t e r p r e t a t i o n o f X-ray d i f f r a c t i o n p a t t e r n s o f m i x t u r e s . 11. A d i a b a t i c p r i n c i p l e of X-ray d i f f r a c t i o n a n a l y s i s o f m i n e r a l s . 3. appl. C r y s t a l l o g r . , 7: 526-531. Elgabaly, M.M. (1962) The presence o f a t t a p u l g i t e i n some s o i l s of t h e western d e s e r t o f Egypt. S o i l Sci., 93: 387-390. E l p r i n c e , M., Mashhady, A.S. and Aba-Husayn, M.M. (1979) The occurrence o f pedogenic p a l y g o r s k i t e ( a t t a p u l i g i t e ) i n Saudi Arabia. S o i l Sci., 128: 21 1-218. Jenkins, D.A. (1976) Observations on t h e s o i l s o f t h e A g r i c u l t u r a l Research Centre, Hofuf, Saudi Arabia. P u b l i c a t i o n No. 66, J o i n t A g r i c u l t u r a l Research and Development P r o j e c t , U n i v e r s i t y C o l l e g e of N o r t h Wales, Bangor and M i n i s t r y o f A g r i c u l t u r e and Water, Saudi Arabia.

186

Mashhady, A.S., Reda, M., Wilson, M.J. and Mackenzie, R.C. (1980) Clay and s i l t mineralogy o f some s o i l s from Qasim, Saudi Arabia. J . S o i l Sci., 31: 101-1 15. M i l l e r , G. (1961) P a l y g o r s k i t und S e p i o l i t h i n t e r t i z r e n und quaternxren Sedimenten von Hadramaut (S-Arabien). Neues Jb. Miner. Abh., 97: 275-288. Singer, A. and Norrish, K.(1974) Pedogenic p a l y g o r s k i t e occurrences i n A u s t r a l i a . Am. Miner., 59: 508-517. Yaalon, D.H. and Wieder, M. (1976) Pedogenic p a l y g o r s k i t e i n some a r i d brown ( c a l c i o r t h i d ) s o i l s of I s r a e l . C l a y M i n e r a l s , 11: 73-80. Zelazny , L.W. and Calhoun, F.G. (1977) P a l y g o r s k i t e ( a t t a p u l g i t e ) , s e p i o l i t e , t a l c , p y r o p h y l l i t e and z e o l i t e s . I n J.B. Dixon and S.B. Weed, e d i t o r s . M i n e r a l s i n S o i l Environments. S o i l Science S o c i e t y o f America, Madison, Wisconsin, pp. 435-470.

187

OCCURRENCE OF PALYGORSKITE I N THE SOILS AND ROCKS OF THE JORDAN VALLEY*

H. SHADFAN S o i l s and I r r i g a t i o n Dept.,

F a c u l t y o f A g r i c u l t u r e , U n i v e r s i t y o f Jordan,

Amman, Jordan J. B . D I X O N

:

S o i l & Crop Sciences Dept.,

Texas A&M U n i v e r s i t y , C o l l e g e S t a t i o n , Texas,

U.S.A. ABSTRACT The p r o p e r t i e s and r e l a t i v e d i s t r i b u t i o n o f p a l y g o r s k i t e i n t h e c l a y f r a c t i o n s o f t h e J u r a s s i c , Cretaceous, T e r t i a r y , and Q u a t e r n a r y rocks exposed on t h e e a s t e r n s i d e of t h e Jordan V a l l e y were i n v e s t i g a t e d by x - r a y d i f f r a c t i o n , e l e c t r o n microscopy and t o t a l chemical a n a l y s i s .

P a l y g o r s k i t e was

nbserved o n l y i n t h e upper Cretaceous and T e r t i a r y l i m e s t o n e s .

The f i n e c l a y

( 4 . 2 um) o f T e r t i a r y l i m e s t o n e c o n t a i n e d h i g h e r amounts o f p a l y g o r s k i t e and Plg r e l a t i v e t o upper Cretaceous l i m e s t o n e .

The p a l y g o r s k i t e f i b e r s i n t h e

T e r t i a r y l i m e s t o n e were u n i f o r m i n l e n g t h and w i d t h , u n l i k e those of t h e p a l y g o r s k i t e i n t h e upper Cretaceous 1 imestone. The l a c u s t r i n e sediments ( L i s a n M a r l ) w i t h i n t h e Jordan V a l l e y and t h e a l l u v i a l - c o l l u v i a l s o i l s a s s o c i a t e d w i t h t h e s e sediments a l s o c o n t a i n e d a p p r e c i a b l e amounts o f p a l y g o r s k i t e .

The p a l y g o r s k i t e i n these s o i l s appears

t o be m a i n l y i n h e r i t e d f r o m t h e exposed l i m e s t o n e s and t h e l a c u s t r i n e sediments. The s o i l s i n t h e s o u t h e r n p a r t o f t h e Jordan V a l l e y c o n t a i n e d h i g h e r amounts o f p a l y g o r s k i t e as w e l l as s o l u b l e s a l t s and gypsum r e l a t i v e t o those i n t h e northern p a r t .

I n g e n e r a l , p a l y g o r s k i t e c o n t e n t s were observed t o be h i g h e r

i n the t o p s o i l than the subsoil.

T h i s may i n d i c a t e t h e f o r m a t i o n o f some

pedogenic p a l y g o r s k i t e i n a d d i t i o n t o t h a t p o r t i o n i n h e r i t e d f r o m p a r e n t material. INTRODUCTION P a l y g o r s k i t e has been observed i n many a r i d s o i l s and sediments i n most M i d d l e E a s t c o u n t r i e s n e i g h b o r i n g Jordan.

M u i r (1951 ) r e p o r t e d t h e presence

o f p a l y g o r s k i t e i n brown c a l c a r e o u s d e s e r t s o i l s i n S y r i a .

Yaalon (1955),

Barshad e t a l . ( 1 9 5 6 ) , X a v i k o v i t c h e t a l . ( 1 9 6 0 ) , S i n a e r (1971), and Yaalon and Wieder (1976) found t h a t m i n e r a l i n c a l c a r e o u s s o i l s i n I s r a e l .

I n the

d e s e r t s o i l s o f Saudi A r a b i a , Aba-Husayn and Sayegh (1977) and Dixon e t a l . (1980) r e p o r t e d t h e presence o f p a l y g o r s k i t e . Al-Rawi e t a l . (1969) and * Presented a t t h e l n t e r n a t l o n a l C l a y Conference 1981

188

Eswaran and Barzanji (1974) reported palygorskite i n a l l u v i a l s o i l s i n Iraq. Elgabaly (1962) indicated t h e presence of palygorskite in t h e western d e s e r t of Egypt, and Hassouba and Shaw (1980) found i t in Quaternary sediments of t h e coastal plain i n t h e northwestern p a r t of t h e country. Many of t h e previous reports indicated t h a t t h i s mineral was i n h e r i t e d from calcareous sediments rich in palygorskite. In recent years several authors have reported t h e occurrence of pedogenic palygorskite i n the same Geographic area (Yaalon a n d Wieder, 1976; Eswaran and Earzanji, 1974; and Hassouba and Shaw, 1980). There i s a lack of information a b o u t the presence, d i s t r i b u t i o n , and occurrence of palygorskite in t h e s o i l s of Jordan. Wiersma (1970) noted t h e presence of palygorskite in some s o i l s and sediments in the Jordan Valley a r e a , whereas the i n v e s t i g a t i o n by Shamali (1966) indicated no evidence of palygors k i t e in many s o i l s of t h a t a r e a . The o b j e c t i v e of t h i s study i s t o determine the d i s t r i b u t i o n , abundance and properties of palygorskite in s o i l s and rocks in t h e Jordan Valley area and t o discuss t h e possible o r i g i n s of the s o i l palygorskite. MATERIALS AND METHODS The Jordan Valley forms a small section (approximately 105 k m ) of t h e East African-Asia Minor R i f t System. The f l o o r of the Valley r i s e s gradually from t h e Dead Sea 392 m below sea level in the south t o 212 m below sea level a t Lake Tiberias i n t h e n o r t h with a width of 5 t o 20 k m . Unconsolidated Quaternary and l e s s commonly Neogene (Miocene and Pliocene) l a c u s t r i n e sediments (Lisan Marl) occupy most of t h e f l o o r of the Valley (Figure 1 ; Bender, 1975). The L i s a n Marl c o n s i s t s of varve-bedded marl a n d s h a l e t h a t contain gypsum and soluble s a l t s . The p a r t of the Transjordan block which i s exposed on t h e eastern s i d e of the Jordan Valley i s covered mainly with Upper Cretaceous limestone. In t h e northern p a r t of the block, T e r t i a r y limestone and Quaternary b a s a l t a l s o outcrop. Below t h e Upper Cretaceous limestone, a l a y e r of sandstone of lower Cretaceous age r e s t s on J u r a s s i c marly limestone (Bender, 1968). In the Valley, the Ghor s o i l and associated s e r i e s have formed from c o l l u v i a l m a t e r i a l s from t h e bordering uplands a n d the underlying Lisan Marl (Dar Al-Handsah, 1967). The colluvium i s several meters thick on t h e marl in the north and very shallow, 20 t o 40 cm, in some areas in t h e south. The texture of s o i l s formed on colluvium varies widely and ranges from clay t o sandy loam depending on t h e conditions of deposition. They a r e highly calcareous, with low organic matter content and weak horizon development e s p e c i a l l y i n the south. The Katar s o i l s and associated s e r i e s a r e found along t h e Jordan River i n the t r a n s i t i o n zone between Ghor and associated s o i l and t h e new flood p l a i n o f the r i v e r t h a t i s found 30 t o 60 m below.

189

Figure 1

GEOLOGICAL MAP OF AREA STUDIED ICompllmd by F. Bmndmr 1o(yll rnodllied

1

,

10

20 hm

SAMPLE IDCATION

Quaternary, B a s a l t

n

Quaternary; Marl s , Clays, F l u v i a t i l e Deposits T e r t i a r y ; Limestone

Upper Cretaceous; Limestone, Marls

Cretaceous; MRiEYar L i mestone Low r Cretaceous; San3stone J u r a s s i c ; Limestone, Calcareous Sandstone

TURKEY

The s o i l s a r e s u b j e c t e d t o e r o s i o n ; t h e r e f o r e , t h e y a r e h i l l y and t h e L i s a n irlar! f r e q u e n t l y i s exposed a t t h e s u r f a c e .

T h e i r p r o p e r t i e s are l a r g e l y i n h e r i t e d from t h e l a c u s t r i n e sediments which a r e v a r i a b l e i n t e x t u r e and have

high s a l i n i t y e s p e c i a l l y i n the southern p a r t o f the Valley. The c l i m a t e i n t h e area o f t h e V a l l e y i s a r i d w i t h a mean annual r a i n f a l l o f

50 t o 100 mm i n t h e s o u t h n e a r t h e Dead Sea and 250 t o 350 mm i n t h e n o r t h . For s t u d y i n g t h e o r i g i n and d i s t r i b u t i o n o f p a l y g o r s k i t e t h e r o c k s which a r e exposed i n t h e Jordan V a l l e y have been sampled f r o m t h e e a s t e r n s i d e o f t h e v a l l e y as f o l l o w s ( s e e Map, F i g . 1 ) .

190

( I ) Marly limestone of J u r a s s i c age i s composed mainly of c a l c i t e , q u a r t z , gypsum and k a o l i n i t e . I t covers a small area in the middle of t h e Valley. (11) Sandstone o f lower Cretaceous age c o n s i s t s of coarse sand, k a o l i n i t e and iron oxides. The exposures of the rock a r e s c a t t e r e d i n the middle and southern p a r t o f the Jordan Valley. (111) Nodular limestone of upper Cretaceous age i s mainly c a l c i t e . I t occupies a l a r g e area i n . t h e middle and southern p a r t of the Valley. (IV) Marly t o hard limestone of upper Cretaceous age c o n s i s t s of c a l c i t e and in some areas dolomite. I t covers the l a r g e s t area in the e a s t e r n Jordanian Upland. (V) Chalky limestone from T e r t i a r y i s composed of c a l c i t e . I t occupies a l a r g e area i n t h e northern p a r t of Jordan. ( V I ) S l i g h t l y weathered b a s a l t of Quaternary age contains high a m u n t s of calcium and sodium feldspars and i s mainly found in the northeastern p a r t o f t h e country. ( V I I ) Lacustrine' sediments (Lisan Marl) of Quaternary o r i g i n c o n s i s t of carbonate, gypsum, soluble s a l t s , q u a r t z and clays. They occupy the f l o o r of t h e Jordan Valley. The rock samples were ground, sieved with a 50 pm s i e v e , and t r e a t e d with 1 N NaOAc, pH=5 f o r carbonate removal (Jackson,, 1969). The <2 pm and <0.2 pm clay f r a c t i o n s were separated by centrifuge and analyzed with a P h i l i p s x-ray diffractometer with a graphite monochromator and a C u t a r g e t x-ray tube operated a t 35 kV and 15 mA. Transmission e l e c t r o n microscopy was used t o i d e n t i f y t h e fibrous minerals in the clay f r a c t i o n s . Six s o i l p r o f i l e s were sampled in the Jordan Valley. Soil p r o f i l e s 1 , 2 , and 3 were formed on Lisan Marl (Katar s e r i e s and associated s o i l s ) from the north t o the south of the Valley, respectively. Soil p r o f i l e s 4 , 5, and 6 were formed on c o l l u v i a l - a l l u v i a l materials (Ghor and associated s o i l s e r i e s ) from the north t o the south of the Valley ( s e e Map, Fig. 1 ) . Carbonate ( c a l c i m e t e r method), e l e c t r i c a l conductivity ( s a t u r a t e d e x t r a c t ) , cation exchange capacity (Na-OAc-method), and mechanical a n a l y s i s ( p i p e t method) described by Black (1965) were conducted on the s o i l samples. Gypsum was determined usina t h e p r e c i p i t a t i o n method with acetone described in Handbook 60 (1954). After t h e removal of carbonates by t r e a t i n g t h e 4 0 pm f r a c t i o n (Jackson, 1969), t h e clay f r a c t i o n s ( 4 pm and <0.2 pm) were separated. The f i n e clays ( ~ 0 . 2pm) were examined by x-ray and transmission e l e c t r o n microscopy and preliminary r e s u l t s showed t h a t the fibrous minerals a r e concentrated i n the <0.2 pm f r a c t i o n s ; s i m i l a r r e s u l t s were obtained by McLean e t a l . (1972). These f i n e clays a r e the s u b j e c t of t h i s r e p o r t . Total chemical analyses by HF d i s s o l u t i o n (Jackson, 1969), and elemental determination by atomic absorption using acetylene and nitrous oxide gases, were c a r r i e d out on the <0.2 pm clay f r a c t i o n s o f Cretaceous (IV) and T e r t i a r y ( V ) rock samples and subsoil samples from p r o f i l e s 3 (35-70 cm) and 6 (75-95 cm) to represent both s o i l s e r i e s .

191 RESULTS AND D I S C U S S I O N The c l a y f r a c t i o n s (12 pm) o f t h e J u r a s s i c l i m e s t o n e ( I ) and Cretaceous sandstone ( 1 1 ) c o n s i s t m a i n l y o f k a o l i n i t e w i t h a p p r e c i a b l e amounts o f mica and 2 : l mixed l a y e r c l a y whereas, t h e c l a y f r a c t i o n s o f upper Cretaceous l i w s t o n e ( I 1 1 and I V ) and t h e s l i g h t l y weathered b a s a l t ( V I ) a r e m a i n l y s m e c t i t e w i t h l o w amounts o f k a o l i n i t e .

P a l y g o r s k i t e i s p r e s e n t i n a small

amount i n t h e l i m e s t o n e o f t h e upper Cretaceous ( I V ) and as a m a j o r component i n the T e r t i a r y limestone (V).

The <2 um f r a c t i o n o f t h e L i s a n M a r l ( V I I )

c o n t a i n e d s m e c t i t e , k a o l i n i t e , p a l y g o r s k i t e , and i l l i t e ( d a t a n o t shown). The XRD p a t t e r n s o f t h e f i n e c l a y f r a c t i o n ( 1 0 . 2 urn) o f t h e J u r a s s i c m a r l y l i m e s t o n e ( I ) and l o w e r Cretaceous sandstone ( 1 1 ) i n d i c a t e d h i g h amounts o f k a o l i n i t e and mixed l a y e r c l a y , mica/vermiculite/smectite (XRD d a t a o f K - s a t u r a t e d samples a r e n o t shown), w i t h a p p r e c i a b l e amounts o f mica e s p e c i a l l y i n t h e sandstone ( F i g . 2 ) .

No e v i d e n c e o f p a l y g o r s k i t e was observed

w i t h t h e t r a n s m i s s i o n e l e c t r o n microscope f o r e i t h e r c l a y f r a c t i o n ( d a t a n o t shown).

The f i n e c l a y o f upper Cretaceous l i m e s t o n e s ( I 1 1 and I V ) , c o n s i s t s

m a i n l y o f s m e c t i t e w i t h s m a l l amounts o f mica ( i n d i c a t e d by K20; Table 2 ) and No p a l y g o r s k i t e was found i n t h e c l a y f r a c t i o n o f t h e

traces o f k a o l i n i t e .

n o d u l a r l i m e s t o n e ( 1 1 1 ) , whereas t h e l i m e s t o n e ( I V ) showed a p p r e c i a b l e amounts o f palygorskite.

The <0.2 urn c l a y o f t h e T e r t i a r y l i m e s t o n e (V) c o n s i s t e d

m a i n l y o f p a l y g o r s k i t e w i t h s m a l l amounts o f s m e c t i t e .

The evidence o f

p a l y g o r s k i t e i n t h e upper Cretaceous and T e r t i a r y l i m e s t o n e s agreed w i t h t h e r e s u l t s o b t a i n e d by Wiersma ( 1 970).

The o c c u r r e n c e o f p a l y g o r s k i t e i n T e r t i a r y

l i m e s t o n e has been r e p o r t e d w i d e l y i n t h e w o r l d . p a l y g o r s k i t e i n Eocene l i m e s t o n e o f I s r a e l .

Yaalon (1955) r e p o r t e d

M i l l o t (1970) showed t h a t most

p a l y g o r s k i t e i n West A f r i c a i s found i n t h e l o w e r T e r t i a r y .

Bigham e t a l .

(1980) found p a l y g o r s k i t e t o be widespread i n l a t e Cenozoic sediments o f t h e Texas High P l a i n s .

In o l d e r sediments Lucas, c i t e d by M i l l o t (1970), found

p a l y g o r s k i t e i n t h e P e r m o - T r i a s s i c i n Morocco, w h i l e Yaalon (1955) found t h e m i n e r a l t o be o f r a r e o c c u r r e n c e i n sediments o l d e r t h a n T e r t i a r y . Transmission e l e c t r o n micrographs o f t h e f i n e c l a y f r a c t i o n ( F i g . 5 ) i n d i c a t e d t h a t t h e f i b e r s i n t h e T e r t i a r y l i m e s t o n e were more u n i f o r m i n l e n g t h and w i d t h t h a n those i n t h e upper Cretaceous l i m e s t o n e . chemical c o m p o s i t i o n o f t h e 40.2

The t o t a l

c l a y ( T a b l e 2 ) showed h i g h e r Mg c o n t e n t i n

t h e T e r t i a r y l i m e s t o n e r e l a t i v e t o t h e upper Cretaceous ( I V ) l i m e s t o n e .

The

h i g h e r c o n t e n t o f A l , Fe, and K i n d i c a t e d t h e presence o f a p p r e c i a b l e amounts o f s m e c t i t e and mica.

The chemical c o m p o s i t i o n o f t h e T e r t i a r y p a l y g o r s k i t e

was s i m i l a r t o t h a t o b t a i n e d b y S i n g e r and N o r r i s h (1974) f o r t h e M t . F l i n d e r s palygorskite.

The f i n e c l a y f r a c t i o n o f t h e s l i g h t l y weathered Q u a t e r n a r y

B a s a l t ( V I ) c o n t a i n e d m a i n l y s m e c t i t e and a s m a l l amount o f k a o l i n i t e ( F i g . 2). The f i n e c l a y o f t h e Q u a t e r n a r y l a c u s t r i n e sediment ( V I I ) c o n s i s t e d o f s m e c t i t e ,

192

k a o l i n i t e , palygorskite and probably a l i t t l e mica (palygorskite was i d e n t i f i e d by t r a n s mission e l e c t r o n microscope, data not shovdn).

M g sat., air dried

Abed and He1 mdach ( 1 981 ) found kaol i n i t e , i l l i t e , and i 11i te/montmri 1 loni t e mi xed l a y e r s with no palygorskite in t h a t sediment, y e t the presence of palygorskite i n l a c u s t r i n e sediments has been reported by Mi1 l o t ( 1 970) and by many o t h e r s . I n general, the investigated s o i l s contained more soluble s a l t s and gypsum in

1ooocps 3.581

VII

the southern p a r t of the valley. All of the s o i l s contained appreciable amounts of

& I

30

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028

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Fig. 2 . X-ray d i f f r a c t i o n p a t t e r n s f o r f i n e clay (<0.2 vm) f r a c t i o n s from rock exposures on t h e eastern s i d e of t h e Jordan Valley ( f o r explanation of rock numbers I - V I I , see t e x t ) .

cal ci um carbonate (Table 1 ) . The lower rainf a l l in the southern p a r t o f t h e valley and the s a l i n i t y o f the l a c u s t r i n e sediments i n the south explain the trend i n s a l t d i s t r i bution (Dar Al-Handsah, 1967). The t e x t u r e of the s o i l s which ranges from clay t o sandy loam, i s variable from place t o place depending on the mode o f sedimentation (Table 1 ) . The cation exchange capacity calculated on a per u n i t o f clay b a s i s ranges from 0.3 t o 0.6 meq per g of clay ( i . e . assuming CEC i s from the c l a y ) thus suggesting the presence of appreciable smectite in a l l the s o i l s . The dominance of smectite in the clay f r a c t i o n (<2 p m ) , with variable amounts of k a o l i n i t e , palygorskite, and mica was determined by x-ray d i f f r a c t i o n (data not shown ) . The f i n e clays of the Katar s o i l and associated s e r i e s contained mostly s m e c t i t e , palygorskite, a n d small amounts of k a o l i n i t e a n d mica (Fig. 3 ) . The amounts of palygorski t e increased in the southern p a r t of the valley ( p r o f i l e 3 ) , whereas the smectite content decreased. Soil p r o f i l e 3 has a CEC per u n i t of clay of 0 . 3 meq per g t h a t supports the inference from x-ray d i f f r a c t i o n and e l e c t r o n microscopy data

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194 t h a t i t contains the l e a s t smectite.

Also, the smectite i s very f i n e grained

as suggested by t h e b r o a d x - r a y d i f f r a c t i o n peak and t h e e l e c t r o n m i c r o g r a p h (Fig. 5-3).

The s m e c t i t e i n f i n e c l a y s f r o m p r o f i l e s 1 and 2 i s c o a r s e r

g r a i n e d t h a n t h a t f r o m p r o f i l e 3.

There appears t o be a p r o g r e s s i v e decrease

i n s m e c t i t e p l a t e t h i c k n e s s f r o m n o r t h t o s o u t h based on i n c r e a s i n g b r e a d t h o f t h e f i r s t o r d e r b a s a l peak ( F i g . 3 ) .

Transmission e l e c t r o n micrographs

( F i g . 5 ) showed t h a t t h e p a l y g o r s k i t e f i b e r s o f t h e f i n e c l a y f r a c t i o n o f p r o f i l e 1 were s i m i l a r i n l e n g t h and w i d t h t o those i n p r o f i l e 3. T h i s may i n d i c a t e t h e u n i f o r m i t y o f p a l y g o r s k i t e i n t h e l a c u s t r i n e s o i l s i n t h e Jordan The h i g h c o n t e n t o f p a l y g o r s k i t e r e l a t i v e t o s m e c t i t e i n p r o f i l e 3

Valley.

c o u l d be due e i t h e r t o minimal w e a t h e r i n g caused by l o w e r r a i n f a l l o r t o t h e f a v o r a b l e c o n d i t i o n s o f f o r m a t i o n o f p a l y g o r s k i t e due t o h i g h s a l i n i t y and gypsum c o n t e n t i n t h e l a c u s t r i n e m a t e r i a l s i n t h e s o u t h e r n p a r t o f t h e v a l l e y . i?.zA

rq.2A Mg sat., air dried c0.2 pl 1000cps

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F i g . 3. X-ray d i f f r a c t i o n p a t t e r n s f o r f i n e c l a y (<0.2 urn) f r a c t i o n s f r o m K a t a r s o i l and a s s o c i a t e d s e r i e s formed f r o m l a c u s t r i n e d e p o s i t s i n t h e Jordan V a l l e y ( f o r e x p l a n a t i o n o f s o i l p r o f i l e numbers 1-3, see t e x t ) . F i g . 4. X-ray d i f f r a c t i o n p a t t e r n s f o r f i n e c l a y (<0.2 pm) f r a c t i o n s f r o m Ghor s o i l and a s s o c i a t e d s e r i e s formed on c o l l u v i a l d e p o s i t s i n t h e Jordan V a l l e y ( f o r e x p l a n a t i o n o f s o i l p r o f i l e numbers 4-6, see t e x t ) .

195

F i g . 5. Transmission e l e c t r o n micrographs f o r f i n e c l a y (<0.2 urn) f r a c t i o n s f r o m r o c k and s o i l samples i n t h e Jordan V a l l e y a r e a ( f o r e x p l a n a t i o n s o f s o i l p r o f i l e numbers 1, 3, 4, and 6, and r o c k s I V and V, see t e x t ) .

196

The f i n e c l a y s f r o m s o i l s formed f r o m c o l l u v i a l and a l l u v i a l m a t e r i a l s c o n t a i n e d t h e same s u i t e - o f m i n e r a l s as those f r o m l a c u s t r i n e d e p o s i t s i.e. s m e c t i t e , p a l y g o r s k i t e , k a o l i n i t e , and p r o b a b l y a l i t t l e mica.

Although

mica i s n o t always e v i d e n t i n t h e x - r a y d i f f r g c t i o n d a t a ( F i g . 4 ) i t i s suggested b y t h e K20 c o n t e n t o f t h e c l a y s ( T a b l e 2 ) .

S m e c t i t e was t h e

dominant m i n e r a l i n t h e f i n e c l a y f r a c t i o n o f t h e s e s o i l s .

Thinner smectite

p l a t e s and l e s s s m e c t i t e i s suggested by r e l a t i v e x - r a y peak h e i g h t and b r e a d t h o f s u r f a c e versus s u b s o i l l a y e r s ( F i g . 4 ) .

Less s m e c t i t e a l s o i s e v i d e n t i n

t h e l o w e r c a t i o n exchange p e r u n i t o f c l a y f o r s u r f a c e h o r i z o n s o f p r o f i l e s 5 and 6 .

The values were about t h e same f o r p r o f i l e 4.

These d i f f e r e n c e s seem

As i n the s o i l s from

t o imply weathering o f smectite i n surface horizons.

l a c u s t r i n e d e p o s i t s , t h e amount o f p a l y g o r s k i t e tended t o be h i g h e r i n t h e southern p a r t o f the v a l l e y ( p r o f i l e 6 ) .

However, p r o f i l e 4 showed a h i g h e r

c o n t e n t o f p a l y g o r s k i t e because t h e s o i l i s c l o s e r t o t h e T e r t i a r y l i m e s t o n e which c o n t a i n e d a h i g h a m u n t o f p a l y g o r s k i t e .

The p a l y g o r s k i t e i n t h e s e

s o i l s appears t o be a t l e a s t p a r t i a l l y i n h e r i t e d f r o m t h e exposed l i m e s t o n e and t h e l a c u s t r i n e sediments w i t h i n t h e Jordan V a l l e y .

The t r a n s m i s s i o n

e l e c t r o n micrographs ( F i g . 5 ) o f p r o f i l e s 4 and 6 i n d i c a t e d a d i f f e r e n c e i n f i b e r p r o p e r t i e s , where t h e y were s h o r t e r and t h i c k e r i n t h e n o r t h e r n p a r t o f t h e v a l l e y ( p r o f i l e 4 ) and l o n g e r and t h i n n e r i n p r o f i l e 6.

The h i g h e r r a i n -

f a l l i n the northern p a r t o f the v a l l e y increased the r a t e o f p a l y g o r s k i t e degradation, w h i l e the smectite content increased.

The h i g h e r Mg c o n t e n t i n

the f i n e c l a y of p r o f i l e 6 r e l a t i v e t o p r o f i l e 3 (Table 2 ) i n d i c a t e d higher content o f p a l y g o r s k i t e i n c o l l u v i a l s o i l s r e l a t i v e t o the s o i l s from l a c u s t r i n e deposits. TABLE 2. Chemical c o m p o s i t i o n o f f i n e c l a y f o r r o c k and s o i l samples i n t h e Jordan V a l l e y t

Sample

Si02

A1203

IV

58.0 56.2 54.1 52.7

12.2 5.7 11.8 8.4

V

3 6 'For

MgO 5.8 13.0 6.9 13.4

Fe203

CaO

K20

Na20

7.5 4.8 8.5 7.0

0.1 1.8 0.3 0.3

0.7 0.2 1.2 1.0

0.2 0.2 0.2 0.1

H20

Total

14.2 17.4 15.1 16.0

98.7 99.3 98.1 98.9

e x p l a n a t i o n s o f r o c k numbers I V , and V, and p r o f i l e s 3

(35-70 cm) and 6(75-95 cm), see t e x t .

197

I n most s o i l s s t u d i e d , p a l y g o r s k i t e c o n t e n t s appeared t o b e h i g h e r i n t h e top s o i l than t h e subsoil.

T h i s may i n d i c a t e some pedogenic f o r m a t i o n o f

p a l y g o r s k i t e i n a d d i t i o n t o i n h e r i t a n c e from the parent rocks i n these h i g h l y calcareous and g y p s i f e r o u s s o i l s o r i t may b e b r o u g h t b y w i n d f r o m t h e n e i g h b o r i n g p a l y g o r s k i t e - r i c h l i m e s t o n e areas.

Eswaran and B a r z a n j i (1974)

and many o t h e r s suggested t h e n e o f o r m a t i o n o f p a l y g o r s k i i e i n h i g h l y c a l c a r e o u s and g y p s i c s o i l s .

Eswaran and B a r z a n j i (1974) i n d i c a t e d t h a t t h e maximum

occurrence o f p a l y g o r s k i t e i n s o i l s appeared a t a s o i l pH o f 7.9, and i t s c o n t e n t showqd a p a r a b o l i c a s s o c i a t i o n w i t h t h o s e o f gypsum and c a l c i t e .

They

concluded f r o m m i c r o m o r p h o l o g i c a l s t u d i e s t h a t p a l y g o r s k i t e has been formed as a c o a t i n g on t h e gypsum g r a i n s .

F u r t h e r i n v e s t i g a t i o n s on Jordan V a l l e y

s o i l s a r e needed i n o r d e r t o d e t e r m i n e i f pedooenic f o r m a t i o n o f p a l y g o r s k i t e occurs under t h e s e c o n d i t i o n s . ACKNOWLEDGMENTS The a u t h o r s g r a t e f u l l y acknowledge t h e a s s i s t a n c e o f L. A. Kippenberger i n x-ray d i f f r a c t i o n and J . Ehrman i n t h e e l e c t r o n microscopy work.

Thanks

a r e extended t o U n i t e d S t a t e s Agency f o r I n t e r n a t i o n a l Development f o r sponsoring t h i s r e s e a r c h work a t Texas A&M U n i v e r s i t y . REFERENCES

Aba-Husayn, M.M. and Sayegh, A.H. 1977. M i n e r a l o g y o f Al-Hasa d e s e r t s o i l s (Saudi A r a b i a ) . Clays C l a y M i n e r . 25: 138-147. Abed, A.M. and Helmdach, F. 1981. B i o s t r a t i g r a p h y and m i n e r a l o g y o f t h e L i s a n S e r i e s ( P l e i s t o c e n e ) i n t h e Jordan V a l l e y . B e r l i n e r geowiss. Abh. (A)32, 123-133. Al-Rawi, A.H., Jackson, M.L., and Hole, F.D. 1969. M i n e r a l o g y o f some a r i d and s e m i - a r i d l a n d s o i l s o f I r a q . S o i l S c i . 107: 450-486. Barshad, I . , Halevy, E., Gold, H.A., and Hagin, J. 1956. Clay m i n e r a l s i n some l i m e s t o n e s o i l s from I s r a e l . S o i l S c i . 81: 423-437. Bender, F. 1968. G e o l o g i e von J o r d a n i e n : B e i t r . r e g i o n a l e n Geologie Erde, v. 7, 230 p . , B e r l i n , Gebrueder B o r n t r a e g e r . Bender, F. 1975. Geology o f t h e A r a b i a n P e n i n s u l a , Jordan. U n i t e d S t a t e s Government P r i n t i n g O f f i c e , Washington, D.C. Bigham, J.M., Jaynes, W.T., and A l l e n , B.L. 1980. Pedogenic d e g r a d a t i o n o f s e p i o l i t e and p a l y g o r s k i t e on t h e Texas High P l a i n s . S o i l S c i . SOC. Am. J. 44: 159-167. B l a c k , C.A. 1965. Methods o f S o i l A n a l y s i s . Am. SOC. Agron. Madison, Wisconsin U.S.A. Oar Al-Handsah. 1967. Jordan V a l l e y P r o j e c t . Agro- and Socio-economic Study, Vol. 11. Dixon, J.B., V i a n i , B . E . , and Lee, S.Y. 1980. The s t u d y o f t h e p h y s i c a l , chemical and m i n e r a l o g i c a l p r o p e r t i e s o f c e r t a i n s o i l areas i n t h e Kingdom o f Saudi A r a b i a . F i n a l Report. 175-178. E l g a b a l y , M.M. 1962. The presence o f a t t a p u l g i t e i n some s o i l s o f t h e w e s t e r n d e s e r t o f Egypt. S o i l S c i . 93: 387-390. Eswaran, J. and B a r z a n j i , A.F. 1974. Evidence f o r t h e n e o f o r m a t i o n of a t t a p u l g i t e i n some S o i l 5 o f I r a q . 1 0 t h I n t . Congr. S o i l S c i . Trans. Moscow. 7: 154-160.

198

Hassouba, H. and Shaw, H.F. 1980. The occurrence o f palygorskite in Puaternarv sediments-of the coastal Dlain of north-west E -q v ,D t . Clav Minerals. 15: 77-93. Jackson, M . L . 1969. Soil Chemical Analysis Advanced Course. Published by author, Madison, WI. 895 D . McLedn, S.A., Allen, B . L . , and Craig, J.R. 1972. The occurrence o f s e p i o l i t e and a t t a p u l g i t e on the Southern High Plains. Clays Clay Miner. 20: 143-149 Millot, G . 1970. Geology of clays. Springer Verlag, New York. Huir, A . 1951. Notes on Syrian s o i l s . J . Soil Sci. 2 : 163-183. Ravikovitch, S . , Pines, F . , and Ben Yair. 1960. Composition o f c o l l o i d s in s o i l s of I s r a e l . J . Soil S c i . 11: 88-91. Shamali, K . 1966. Zur Kenntnis der Boden des Jordangrabens unter besonderer Berucksichtigung der Tonmineralien. Ph.D. t h e s i s , Giessen, Justus - Liebig Universi t a t . Singer, A. 1971. Clay minerals in the s o i l s o f the southern Golan Height. I s r . J. E a r t h Sci. 20: 105-112. Singer, A., and Norrish, K. 1974. Pedogenic palygorskite occurrences in Australia. Am. Miner. 59: 508-517. United S t a t e s S a l i n i t y Lab. 1954. Diaqnosis a n d improvement o f s a l i n e a n d a l k a l i s o i l s . Agr;cultural Handbook No. 60. U.S.D.A. GIiersma. J . 1973. Provenance, cenesis and paleogeograohical imol i c a t i o n s of microminerals occurring in sedimentary rocks of the Jordan Valley a r e a . Pub1 i c a t i e s van Het Fysisch-Geografisch en Bodem-kundig Lab1 .atoriur;: van de U n i v e r s e i t e i t van Amsterdam. nr. 15. Yaalon, D.H. 1955. Clays and some non-carbonate minerals in imestones and associated s o i l s o f I s r a e l . B u l l . Res. Counc. I s r . , 56, 2 S e c t . B . Zoo: 161-173. Yaalon, D . H . , a n d Wieder, M. 1976. Pedogenic palygorskite in some a r i d brown ( c a l c i o r t h i d ) s o i l s o f I s r a e l . Clay Minerals 1 1 : 73-80.

199

OCCURRENCE OF PALYGORSKITE IN GROUND-WATER RENDZINAS (Petrocalcic calciaquolls) IN SOUTH-EAST SOUTH AUSTRALIA

T. HODGEl, L.W. ThCHENEK2 and J.M.

OADESl

'Department of Soil Science, Waite Agricultural Research Institute, University of Adelaide, South Australia 2Soils Department, Natural Resources Division, Alberta Research Council, Edmonton, Alberta, Canada.

ABSTRACT Palygorskite was the dominant clay mineral in some Ground-water rendzinas developed on Pleistocene interdunal flats in the south-east of South Australia. The clay fraction from one soil contained 9.2% MgO and palygorskite was identified 0

by a prominent 10.5 A X-ray diffraction spacing for the c-axis and by fine rod-like morphology.

The clay had a high charge and surface area and was strongly

associated with organic matter. It is concluded that the palygorskite developed in situ along with smectite in an environment subject to prolonged seasonal inundation by surface waters and groundwaters containing substantial quantities of salts including Ca and Mg.

INTRODUCTION Callen (1983) has indicated that the majority of occurrences of palygorskite are oceanic, but there is an increasing awareness of terrestrial deposits and the occurrence and formation of palygorskite in soils.

Generally palygorskite is

restricted to arid and semi-arid climates (< 300 m annual rainfall) as it is not stable to leaching and the development of acidity.

It has been recognised in a

wide range of terrestrial localities across Australia (Table 1) and has usually been described as a lacustrine deposit (Barnes et al. 1978) or as coatings on soil peds.

It is unusual for it to be the dominant clay mineral in a soil as described

in this paper. Detailed examination of the clay fraction from a Ground-water rendzina from near Millicent, South Australia showed that palygorskite was the dominant clay mineral present.

This observation led to a more extensive sampling of the various

interdune flats in the south-east of the state and an appraisal of the environment which has led to the formation o f palygorskite as a soil clay.

2 00

TABLE 1.

Occurrence of palygorskite in Australian soils

Authors

Locality

Mode of occurrence

Beattie (1970) Beattie and Haldane (1958)

New South Wales Murrumbidgee, New South Wales Murray Bridge, South Australia MacDonnell Ranges Northern Territory South-east of South Australia South-east of South Australia South-east of South Australia Central Australia Ipswich, Queensland Northern Territory New South Wales Lake Eyre, South Australia

In parna

Hutton b Dixon (1981) Litchfield (1969) Norrish and Rogers (1956) Rogers et al. (1956) Pickering (1966) Pickering (1966) Rogers et a l . (1954) Singer & Norrish (1974) Taylor & Pickering (1962)

In parna In calcareous aeolian material under calcrete

In crusts on soil peds Playa lake Playa lake Ground-water rendzina Calcareous red earth Rendzina over dolomite Calcareous red earth Red earth, Red-brown earth Pleistocene clay

LOCALITY AND METHODS The south-east of South Australia The coastal plain of the south-east of South Australia represents the unique preservation of the results of Quaternary sea level oscillations associated with gradual uplift of the land mass.

Various sea stands resulted in a series of

stranded dune systems roughly parallel to the present coast line (Fig. 1). The area represents a seaward sloping plain (50 fourteen ranges are superimposed (Fig. 2 ) .

q

in 100 km) on which some

The most recent investigations in this

area are described by Cook et a1 (1977) and Schwebel (1978). Various dating techniques have established that the Naracoorte Range is <690,000 years old and the Woakwine Range about 100,000 years old.

There is not a

simple age sequence towards the coast as some of the ranges are mainland beach deposits and others were formed as off-shore barriers as the sea levels oscillated (Schwebel 1978). Two depositional modes have been recognised for the interdune flats:

an

estuarine-lagoonal unit closely associated with marine events and a lacustrine unit not dependent on sea level changes, but controlled by the sluggish northerly drainage of surface waters through indefinite channels, swamps and lakes between the ranges. swamps

There is evidence for both recharge of aquifers from such lakes and

and also surfacing of groundwaters in the area.

201

~

Figure 1. Quaternary ranges and sampling sites in the southeast of South Australia.

202

m

West Avenue

Woakwine

I

"

'

UJATERNARY

Figure 2 .

.

#

TERTIARY

Simplified section from the Naracoorte Ranges to the coast

The occurrence distribution and description of Ground-water rendzinas on the interdunal flats has been described in detail by Blackburn (1959) and Blackburn et al. (1965). Sampling One of the largest interdune flats was sampled along its length for about 100 km.

A number of other samples were taken at random from other flats as indicated

in Fig. 1.

Most of the samples were 0-10 cm only, but several sample holes, in

soils known to be dominated by palygorskite, were extended to the underlying limestone at about 60 cm.

In all the cases examined the limestone was almost

entirely calcitic with no indication of dolomite. Laboratory studies One soil in which palygorskite was dominant was examined in detail. Particle size fractionation was determined after ultrasonic dispersion with and without

203 prior chemical treatment to destroy organic matter and carbonates (Turchenek and Oades 1979).

Clay samples were fractionated by continuous flow centrifugation.

A l l fractions were analysed for C and N.

Clay fractions were examined by X-ray

diffraction, by X-ray fluorescence spectrometry to determine the elemental composition, and by trarismission electron microscopy.

Surface areas were

determined by adsorption of cetyl pyridinium bromide. For the remainder of the samples a portion of the clay fraction was obtained by sedimentation techniques and examined by X-ray diffraction for the presence of 0

palygorskite based on a 10.5 A c-axis spacing.

RESULTS AND DISCUSSION Particle size distribution and other properties of a soil in which palygorskite was dominant are presented in Table 2 .

The results of chemical as

well as ultrasonic treatment show a much higher clay content and lower sand and silt content than afer ultrasonic treatment alone.

The chemical treatment

consisted of destruction of carbonates in sodium acetate, pH 5 , oxidation of organic matter with hydrogen peroxide and dispersion in sodium carbonate solution. Without the chemical treatment much of the clay and organic matter remained in microaggregates of silt and sand size.

Other workers have obtained similar

results with calcareous s o i l s (Edwards & Bremner, 1967a and Emerson, 1971). The total elemental analyses of the particle size fractions in Table 3 show 8 to 9% MgO in the various clay fractions.

Palygorskites have been reported with

MgO contents from 5 to 15% (Caillere & Henin, 1961; Rogers et al., 1956; Singer & Norrish, 1974).

X-ray diffraction traces of the clay fractions indicate the presence of kaolinite, quartz and possibly a small amount of expanding silicate clay (Fig. 3 ) 0

The largest peak is however at 10.5 A which with others at 6.44, 5.42, 4.48 and 0

2.56 A (not shown) confirms the presence of palygorskite.

These peaks were found

0

in all fractions. Broad shoulders between 10 and 30 A did not produce reinforced

10 A spacings after K-saturation and heating.

Thus smectite or randomly

interstratified minerals were present in only trace amounts (Fig. 4).

In addition

n

the 10.5

A

peak disappeared after K-saturation and heat treatment at 55OOC (Fig. 4 ) .

It is concluded that while traces of other clay minerals were present palygorskite was dominant.

204

TABLE 2. Description and properties of the soil examined in detail : Ground-water rendzina

Australian Great Soil-Group Association Reference Horizon sampled PH (H20) Organic carbon % Total nitrogen % C/N ratio Inorganic carbon Particle size distribution % Fraction

:

Furner

: Blackburn (1959) : A (0 10 cm) : 8.00 : 5.4 : 0.48

-

:

11

: 0.55

Ultrasonic and Chemical treatment

Ultrasonic treaiment

Coarse silt ( 5-20) ( 2-5) Fine silt

i:: ] ti::]

Coarse clay (0.4-2) Medium clay (0.1-0.4) ((0.1) Fine clay

15.3

Coarse sand (>53 pm) Fine sand (20-53)

17.0

14.8

36.8

24.4

60.8

TABLE 3. Total elemental analysis of particle size fractions

Fraction Whole soil Coarse sand Fine sand Coarse silt Fine silt Coarse clay Medium clay Fine clay Total clay

Fe203 4.8 2.2 1.1 3.3 5.3

6.6 7.0 6.8 6.7

MnO

Ti02

CaO

K20

P205

Si02

A1203

MgO

Total

0.02 0.02 0.01 0.02 0.02 0.02 0.02 0.02 0.02

0.70 0.23 0.74 0.87 0.85 1.05 0.74 0.19 0.69

5.3 11.2 4.1

1.2 0.6 1.3 1.3 1.2 1.2 1.1 1.2 1.2

0.11 0.07 0.04 0.08 0.09 0.15 0.09

71.7 82.3 87.4 77.0 67.6 68.1 66.6 65.9 67.8

11.7 3.1 4.5 9.3 12.9 15.5 16.7 14.8 16.0

5.9 1.7 1.1 4.2 6.3 8.2 8.9 9.6 9.2

101.4 101.4 100.3 100.5 101.3 104.3 102.4 103.2 104.2

4.4 7.0 3.5 1.3

4.6 2.5

0.06 0.10

Since many of the particles obtained in the fractionation procedure occurred in microaggregates, clay separates obtained after chemical treatments were analysed by X-ray diffraction to determine whether mineral segregation had occurred on a particle size basis only.

Except for the presence of quartz in the

coarse clay fraction diffraction traces were similar (Fig. 5).

205

3.35

I 10.5 4.26 Co8r.e

Clay

I

I

3.22

I

5.42

I

wI\

m

Fine CI8y

m

1

30

35

Figure 3.

25

I

I

20

15

5

10

X-ray diffraction traces of clay fractions (Mg-saturated, glycerol-solvated and air-dried samples)

3.35

t Figure 4.

a0

I,

25

2o

28

IS

10

5

X-ray diffraction traces of oriented coarse clay specimens after various treatments (K-saturated specimens have less clay, hence smaller peaks, than the Mg-saturated specimen)

206

/I 4.48

1

1 .

30

I

V

25

20

IS

10

5

28

Figure 5 .

X-ray diffraction traces of coarse clay and medium+fine clays obtained by fractionation after chemical and ultrasonic treatment (Mg-saturated, air-dried samples)

Transmission electron micrographs of the medium and fine clay fractions show the presence of short fibres, mainly aggregated, and larger plate-like particles (Plates 1 and 2 ) .

Plate 1, in particular, shows the rod-like morphology of

palygorskite particles contrasted with a large flake of phyllosilicate.

The

small size of the rods is clearly indicated in Plate 2 in which the small spheres are standard polystyrene balls of 0.088 pm diameter. The rods are of various sizes and occur together in small rafts.

Individual rods or laths appear about

0

100 A across and are 10 to 15 times as long.

The palygorskite is apparently of

the short fibred variety in which the Fe content is relatively high (Zelazny and Calhoun, 1977.).

207

Plate 1 .

Transmission e l e c t r o n micrograph o f f i n e c l a y (bar represents 1 pm)

Plate 2 .

Transmission e l e c t r o n micrograph of f i n e c l a y a f t e r d i t h i o n i t e and peroxide treatments (bar represents 1 pm)

208 The large quantity of clay occurring in microaggregates indicates a strong association of palygorskite and organic matter probably through the influence of 2+

Ca

and Mg

2+

which are the dominant exchangeable cations in the Ground-water

rendzinas. The palygorskite clay had a high Surface area, 210 mz g

-1

.

(cf Singer

and Norrish 1974). Distribution and genesis of the Rendzinas containing palygorskite In an area about 5 km diameter some 8 km northeast of Millicent the clay fractions of all soils sampled were dominated by palygorskite, but further afield clays were sometimes dominated by palygorskite but aiso by other aluminosilicates, usually smectite. (Fig. 1).

Some soils contained similar quantities of the two minerals

Palygorskite was found on several of the interdune flats indicating a

similar environment on various flats even though the various ranges associated with them were formed at different times. The conditions under which palygorskite is likely to form are high pH and suitable concentrations of Mg, Si and A1 (Singer h Norrish, 1974).

Limestones are

abundant in the area and the Ground-water rendzinas invariably grade into calcareous materials at depths of less than one metre.

At several inspection

points the calcareous materials were not dolomitic, and palygorskite was not present at depth. This suggests a pedogenic origin for palygorskite, although the possibility of an aeolian source cannot be excluded. The Ground-water rendzinas and associated swamp soils are characterised by high concentrations of exchangeable Mg (Table 3 ) .

This is well illustrated by comparisons of data for

exchangeable cations of the Rendzinas and swamp soils with various adjacent soils belonging to different Soil Groups.

It is clear that the Ground-water rendzinas

have affinities with the swamp soils which represent current drainage lines, that is, before artificial drainage. The exchangeable cation ratios for the Rendzinas and Swamp soils indicate an equilibrium with interstitial waters rich in Mg. Examination of data for the chemical composition of water in both the surface unconfined aquifer and deeper aquifers shows a marked trend towards the composition of seawater, i.e more Mg and NaCl from water in the major catchment areas around Penola in both a northerly and northeasterly direction (Floegel 1972, Alderman and Skinner 1957).

In fact water in the Coorong, the present interdunal

lagoonal system which is northeast of the study area contains more Mg and NaCl than seawater and is an area where dolomite is forming, but apparently not palygorskite (Von der Borch, Lock, and Schwebel, 1975).

209

TABLE 3 .

Comparison of exchangeable cations of Ground-water rendzinas and adjacent soils (Data from Clarke, 1965, 1966) Cation exchange capacity

Ground-water rendzinas

Swamp soils Red-brown earths Terra rossas

Andos o 1

1 2 3 4 5 1 2 3 1 2 1 2 3 4 5 1

37 58 60 27 58 72 24 35 17 25 23 17 24 19 18 16

m.e. 100 g - l Ca

Mg

K

Na

20 42 43 11 38 44

9.5 6.5 11 11 12 23 10 9 3.7 4.2 1.8 2.4 3.3 3.2 2.0 1.6

1.9 4.8 5.6 2.2 1.7 1.7 1.8 0.9 0.9 2.6 1.0 0.9 1.1 1.2 0.3 0.2

0.6 0.5 0.4 4.3 0.5 5.4 4.3 0.5 0.4 0.4 0.3 0.2 0.3 0.3 0.3 0.6

9

22 7 13

19 11 19

15 15 11

Thus it appears that the interdune flats with sluggish drainage, widespread occurrence of calcareous materials and Mg rich waters produce the chemical environment for the formation of palygorskite and/or smectite.

The prolonged

seasonal flooding which accentuates the growth of grasses has also led to the accumulation of organic matter in swamps and on the Rendzina flats. It is thus not surprising to find a close association of palygorskite and organic matter in this environment The sampling programme was such that no definite conclusions can be drawn concerning the distribution of palygorskite and smectite but it seems as though the chemical environment must be close to the boundary for the stability of the two minerals. The distribution does generally correspond to the model which relates the occurrence of palygorskite to increases in Si:A1 ratios towards the sea and decreases in A1:Mg ratios which result from terrestrial desilication and marine silication processes (Zelazny and Calhoun, 1977). ACKNOWLEDGEMENT We wish to thank Mr. D.C. Lewis of the Southeast Regional Headquarters, South Australian Department of Agriculture, Struan for substantial help with the sampling programme.

210

REFERENCES Alderman, A.R. and Skinn'er, H.W. 1957. Dolomite sedimentation in the southeast of S.A. Am. J . Sci. 255: 561-567. Barnes, L.C., Olliver, J.G. and Spencer, W.G. 1978. Recce sampling of palygorskite deposits, Lake Frome. Miner. Res. Rev. No. 149, South Australian Department of Mines and Energy. Beattie, J.A. 1970. Peculiar features of soil development in parna deposits in the eastern Riverina, New South Wales. Aust. J. Soil Res. 8 : 145-156. Beattie, J.A. and Haldane, A.D. 1958. The occurrence of palygorskite and barytes in certain parna soils of the Murrimbidgee region, New South Wales. Aust. J. Sci. 20: 274-275. Blackburn, G. 1959. The soils of County Grey, South Australia. CSIRO Aust. Div. Soils, Soils and Land Use Series No.'33. Blackburn, G., Bond, R.D. and Clarke, A.R.P. 1965. Soil development associated with stranded beach ridges in southeast South Australia. CSIRO Aust. Div. Soils, Soil Publication No. 22. Caillere, S . and Henin, S. 1961. In "The X-ray identification and crystal structures of clay minerals". (G. Brown, ed). Miner. SOC., London, pp. 323-353. Callen, R. 1983. A survey of palygorskite occurrences. This volume. Clarke, A.R.P. 1965. A laboratory examination of soils of country Grey, South Australia. CSIRO Aust. Div. Rept. 71164. Clarke, A.R.P. 1966. The laboratory examination of soils from counties Macdonnell and Robe, South Australia. CSIRO Aust. Divl. Rept. 4/65. Cook, P.J., Colwell, J.B., Firman,J.B., Lindsay, J.M., Schwebel, D.A. and von der Borch, C.C. 1977. Late Cainozoic sequence of southeast of South Australia and Pleistocene sea level changes. Bureau Miner. Resources Journal 2: 81-88. Edwards, A.P. and Bremner, J.M. 1967a. Dispersion of soil particles by sonic vibration. J. Soil Sci. 18: 47-63. Edwards, A.P. and Bremner, J.M. 1967b. Microaggregates in soils. J. Soil Sci. 18: 64-73.

Emerson, W.W. 1971. Determination of the contents of clay sized particles in soils. J. Soil Sci. 22: 50-59. Floegel, H. 1972. The position of the lower Tertiary artesian aquifer within the hydrogeology and the hydrochemistry of the Gamiber embayment area (South Australia/Victoria). Ph.D. thesis Flinders Univ. Adelaide, South Australia. Hutton, J.T. and Dixon, J.C. 1981. The chemistry and mineralogy of some S.A. calcretes and associated soft carbonates and their dolomitization. J. Geol. SOC. Aust. 28: 71-79. Litchfield, W.H. 1969. Soil surfaces'and sedimentary history near the Macdonnell Ranges, N.T. CSIRO Aust. Soil. Publ. No. 25. Norrish, K. and Rogers, L.E.R. 1956. Mineralogy of some terra rossas and rendzinas of S.A. J. Soil Sci. 7: 294-301. Pickering, J.G. 1966. X-ray diffraction analysis of several soil profiles from the southeast of S.A. and Horsham (Vic). CSIRO Aust. Tech. Mem. 10166. Rogers, L.E.R., Martin, A.E. and Norrish, K. 1954. The occurrence of palygorskite near Ipswich, Queensland. Miner. Mag. 30: 534-540. Rogers, L.E.R., Quirk, J.P. and Norrish, K. 1956. Occurrence of an aluminium-sepiolitf in a soil having unusual water relationships. J. Soil Sci. 7: 177-184. Schwebel, D.A. 1978. Quaternary Stratigraphy of the southeast of South Australia. Ph.D. thesis Flinders University, Adelaide. S.A. Singer, A. and Norrish, K. 1974. Pedogenic palygorskite occurrences in Australia. Am. Miner. 59: 508-517. Taylor, R.M. and Pickering, J.G. 1962. Mineralogy of bore samples from Madigan's Gulf, Lake Eyre, South Australia. CSIRO Aust. Div. Soils. Diol. Rep. No. 5/62 (mimeo). Turchenek, L.W. and Oades, J.M. 1979. Fractionation of organo-mineral complexes by sedimentation and density techniques. Geoderma 21: 311-343. Von der Borch, C.C., Lock, D.E. and Schwebel, D.A. 1975. Groundwater formation of dolomite in the Coorong region of S.A. Geology 3: 283-285. Zelasny, L.W. and Calhoun, F.G. 1977. In "Minerals in soil environments". Eds. J.B. Dixon and S . B . Weed. Soil Sci SOC. Am. Madison, Wisconsin pp 435-470.

211

SEPIOLITE AND PALYGORSKITE IN JAPAN

N. IMAI and R. OTSUKA Department of Mineral Industry, School of Science and Engineering, Waseda University, Tokyo, 160 Japan

ABSTRACT Recent investigations on palygorskite and sepiolite from Japan are summarized in relation to their mode of occurrence and mineral genesis. Description of the Japanese palygorskites has been confined to only two specimens from the Kuzuu district, represented by "karst region" where a thick sequence of carbonate rocks crops out extensively.

These two palygorskites

occur along fissures or faults as fillings and are considered to have been formed by direct precipitation from an aqueous solution at earth-surface temperature.

The solution rich in silica and magnesium with lesser amount of alumin-

ium, resulted from the descent of meteoric water. Japanese sepiolites, on the other hand, show various modes of occurrence, and may be classified largely into four groups on the basis of their mode of occurrence: (1) sepiolite in serpentinite, ( 2 ) sepiolite associated with metallic mineral deposits, ( 3 ) sepiolite from the "karst region", and (4) sepiolite (iron-rich variety) in Tertiary sediments.

The sepiolites are con-

sidered to be of either hydrothermal or supergene origin, and to have been formed by direct crystallization from low-temperature hydrothermal solution and/or from supergene or marine water rich in silica, magnesium and other components. Palygorskite and sepiolite in Japan do not form sedimentary deposits of economical importance, and occur on a small scale.

Intensive studies of clay

mineral compositions in clay fractions of surface marine sediments in the oceans and seas in the environs of the Japanese Island Arc, have not confirmed so

far the presence of palygorskite or sepiolite.

INTRODUCTION Until the earlier half of 1 9 5 0 ' s , no mineralogical description of palygorskite and sepiolite had appeared in any scientific papers of Japan.

This may be

due to the fact that, in our country these two minerals occur only on a small scale, forming no commercially profitable deposits and having no economical

2 12

importance comparable

to

t h a t of " a t t a p u l g i t e " from Attapulgus, U . S . A .

The

f i r s t d e s c r i p t i o n of one of t h e s e two minerals i n Japan was t h a t of s e p i o l i t e from t h e Yoshikawa-mura,

Fukuoka P r e f e c t u r e , by Muraoka e t a l .

(1958).

Until

recent y e a r s , p a l y g o r s k i t e and s e p i o l i t e were regarded a s r a r e minerals i n our country.

Recently, however, t h e s e minerals have been discovered a t s e v e r a l

l o c a l i t i e s i n Japan and d e t a i l e d d e s c r i p t i o n s have been made by a number of investigators. Imai e t a l .

In t h e i r study on t h e Karasawa s e p i o l i t e from t h e KUZUU d i s t r i c t ,

(1966) p r e d i c t e d t h a t s e p i o l i t e might not be a r a r e mineral i n our

country, e s p e c i a l l y i n t h e " k a r s t r e g i o n " , and s t r e s s e d t h a t t h e Karasawa s e p i o l i t e , p r e s e n t i n l a r g e q u a n t i t i e s of t h e pure m a t e r i a l and having an i d e a l chemical composition would c o n t r i b u t e t o t h e mineralogical i n v e s t i q a t i o n of s e p i o l i t e , i n p a r t i c u l a r t o i t s dehydration behaviour on h e a t i n g .

The s t u d i e s

of t h e Karasawa s e p i o l i t e , and t h e &an0 p a l y g o r s k i t e , which was found subsequently i n t h e Kuzuu d i s t r i c t , have produced t h e numerous p u b l i c a t i o n s on t h e i r thermal and i n f r a r e d behaviour ( e . g . , Hayashi e t a l . ,

1969; Otsuka e t a l . ,

Imai e t a l . ,

1969; Otsuka e t a l . ,

1970: Nagata e t a l . ,

1968;

1973).

This paper attempts t o summarize t h e s t u d i e s on p a l y g o r s k i t e s and s e p i o l i t e s c a r r i e d o u t up t o t k p r e s e n t i n Japan, p a r t i c u l a r l y with r e s p e c t t o t h e i r mode of occurrence and mineral g e n e s i s .

PALYGORSKITE General remarks Occurrences of p a l y g o r s k i t e s have been confirmed from s e v e r a l l o c a l i t i e s i n Japan.

They have been found i n m e t a l l i c mineral d e p o s i t s and i n t h e " k a r s t

region", involving limestone caves.

Detailed mineralogical s t u d i e s on t h i s

mineral, however, have been made f o r only two m a t e r i a l s i n t h e Palaeozoic carbonate rocks of t h e Kuzuu d i s t r i c t , Tochigi P r e f e c t u r e .

This shows marked

c o n t r a s t t o t h e numerous r e c e n t p u b l i c a t i o n s on s e p i o l i t e s , which w i l l be mentioned i n t h e next s e c t i o n . P a l y g o r s k i t e from t h e KUZUU d i s t r i c t ( " k a r s t region") The Kuzuu d i s t r i c t is s i t u a t e d 80 k m n o r t h of Tokyo (Fig. 1) and occupies t h e southern margin of t h e Ashio mountains, approximately a t l a t . long. 139O36'E.

36O24'N and

In t h i s d i s t r i c t t h e rocks of t h e Chichibu Palaeozoic System

and t h e overlying Mesozoic formations crop o u t e x t e n s i v e l y .

These system and

formations have been divided i n t o t h e following t h r e e s t r a t i g r a p h i c u n i t s by t h e l i t h o t o p e and biotope; t h e Izuru Formation and t h e Nabeyama Formation (Permian), and t h e Adoyama Formation ( T r i a s s i c ) , i n ascending o r d e r .

The Nabeyama Forma-

t i o n i s a r e p r e s e n t a t i v e of t h e Permian formation i n t h e Ashio Mountains and c o n s i s t s mainly of carbonate rocks.

This carbonate sequence h a s been subdivided

i n t o t h e following t h r e e members by t h e l i t h o t o p e , i n ascending o r d e r ; t h e Lower Limestone Member, t h e Middle Dolostone Member and t h e Upper Limestone Member.

213

- 45"

SEA OF JAPAN

-40"

ff

*O

PACIFIC OCEAN

30

- 33"

a0 0 0

0

.P

130'

Fig. 1 Map of Japan, showing b o t h places and mines g i v e n i n t h e t e x t .

2 14 The lower Nabeyama Formation is the type sequence of the Nabeyama Series representing the ParafusuZina Zone.

Yabeina zone.

The upper limit of the formation reaches the

The Middle Dolostone Member, from 50 to more than 150 m thick,

represents dolomite deposits, that are excellent in both quantity of reserve and quality, and which represent one of the important sources of dolomite ores in our country. Hanezuru palygorskite.

The first occurrence of palygorskite from the Kuzuu

district was reported by Minato (1966).

The palygorskite specimen was found at

the open pit of the Hanezuru mine where .dolomite ores are now mined.

The mine

is located 18 km northwest of the KUZUU Railway Station on the T6bu Sano Line. Here, palygorskite specimens occur as thin films, 2-3 mm thick, which extend to the fresh portions as veinlets on some occasions on the weathered surfaces of blocky dolostones, belonging to the Middle Doiostone Member.

The specimen

investigated, exhibiting leather-like appearance and white in colour, consists of palygorskite and a subordinate amount of dolomite with negligible quartz. Refractive indices are; a

=

1.558, y = 1.567, y

extinction and positive elongation.

-

CI = 0.009.

It shows straight

Perfect purification of the material from

the specimens was unsuccessful and the purified material, still containing 4.22 weight percent dolomite, was analyzed chemically by normal wet method.

The structural formula for the half-unit-cell of palygorskite, calculated from the results of an analysis (after subtracting the dolomite composition, Table 1 (2)) on the basis of the positive charges of cation unit (42) is, IV VI 2+ (Si.7.asAl0.15)18. D O (All.72Feo o 7Ti0.o 3Mg2-1 O ) c3.92Cao. 2 3 0 2 1 (OH)3.58

-

(OH21 3.714-23820 where OH2 represents bound water and H20 includes hygroscopic and zeolitic waters.

This shows that the Al/Mg atomic ratio in octahedral site is about

0.82, which corresponds nearly to that of the Attapulgus palygorskite.

X-ray

powder-diffraction data forthe Hanezuru material show good agreement with those for the Attapulgus palygorskite.

Dispersions for the material gave electron

micrographs showing elongated fibres or lath-like fragments, 1-0.5 pm long, 0.025-0.055 pm wide.

Summarizing the mode of occurrence and the mineralogical

properties of the Hanezuru material, the author considered that the material might have crystallized out in cracks or fissures of dolostone by the action of low-temperature hydrothermal solutions. Egano palygorskite.

The second occurrence of palygorskite in the Kuzuu

district was confirmed from the 6gano mine by Imai (Minato et al., 1969).

The

6gano mine is located about 2 km northeast of the Kuzuu Railway Station on the Tabu Sano Line.

The specimen of the Egano palygorskite occurs on the Ruttery

base adit level as filling of the Zgano No. 10 Fault, running in the direction of N45'-60°E

with a dip of 35°-400NW.

attain about 60 m.

The vertical displacement of this fault

The foot wall of this fault is white dolostone of the

215 TABLE 1

Chemical c o m p o s i t i o n o f p a l y g o r s k i t e s

(1)

(2)*

53.64

53.81

53.75

0.60

0.21

-

8.76

10.85

10.23

3.36

0.65

1.83

0.23

-

0.26

0.03

0.01

-

9.05

9.69

9.39

2.02

1.49

2.29

0.83

-

tr.

0.79

n.d.

n.d.

10.89

11.30

12.04

(3)

0.02

0.75

9.12

8.70

10.16

100.07

96.71

99.97

( 1 ) " A t t a p u l g i t e " from A t t a p u l g u s , G e o r g i a ( B r a d l e y , 1 9 4 0 ) . ( 2 ) P a l y g o r s k i t e from t h e Hanezuru mine, Kuzuu d i s t r i c t , T o c h i g i P r e f e c t u r e (Minato, 1 9 6 6 ) . * A f t e r s u b t r a c t i n g t h e d o l o m i t e c o m p o s i t i o n . ( 3 )P a l y g o r s k i t e from t h e Zgano mine, Kuzuu d i s t r i c t , T o c h i g i P r e f e c t u r e (Minato e t a l . , 1 9 6 9 ) . Middle D o l o s t o n e Member and t h e h a n g i n g w a l l r e p r e s e n t s g r e y i s h w h i t e l i m e s t o n e o f t h e Upper Limestone Member.

The g r e y i s h w h i t e l i m e s t o n e had been b r e c c i a t e d

a l o n g t h i s f a u l t ; t h e b r e c c i a t i o n zone r a n g e s from 1 0 t o 2 0 c m i n w i d t h .

A clay

v e i n , c o n s i s t i n g p r i n c i p a l l y o f p a l y g o r s k i t e , i s developed a l o n g t h i s f a u l t plane.

I t r a n g e s from 1 t o 5 c m i n w i d t h .

The p a l y g o r s k i t e s p e c i m e n s i n One is

q u e s t i o n may b e c l a s s i f i e d i n t o two v a r i e t i e s by e x t e r n a l a p p e a r a n c e .

massive c l a y e y v a r i e t y r a n g i n g i n c o l o u r from p a l e - b r o w n i s h w h i t e t o snow w h i t e , with an e a r t h y appearance.

I n t h e p r e s e n c e o f water, it h a s a h i g h p l a s t i c i t y .

The o t h e r i s a f o l i a t e d v a r i e t y w i t h a p a l e - y e l l o w i s h brown c o l o u r , showing f o l i a t i o n parallel t o t h e f a u l t plane.

Under t h e m i c r o s c o p e , t h e m a s s i v e c l a y e y

v a r i e t y i s s e e n t o c o n s i s t m a i n l y o f f i b r o u s a g g r e g a t e s w i t h f i b r e s 0.05-0.1 l o n g , i n c l u d i n g n e g l i g i b l e amount o f c a l c i t e f r a g m e n t s . t h i n s e c t i o n s , a n d shows p o s i t i v e e l o n g a t i o n .

mm

It i s c o l o u r l e s s i n

The f o l i a t e d v a r i e t y h a s

c a t a c l a s t i c f e a t u r e s , s i n c e it c o n t a i n s numerous c r u s h e d g r a i n s o f c a l c i t e , r a n g i n g from s u b a n g u l a r t o a n g u l a r i n s h a p e , w i t h some w e l l r o u n d e d .

These

c a l c i t e p a r t i c l e s a r e s c a t t e r e d throughout t h e clayey matrix t h a t c o n s i s t s predominantly o f f i b r o u s a g g r e g a t e s o f p a l y g o r s k i t e .

The c a l c u l a t i o n o f t h e

s t r u c t u r a l f o r m u l a from t h e r e s u l t s o f a n a n a l y s i s ( T a b l e 1 ( 3 ) ) on t h e b a s i s o f

216

Fig. 2 Transmission electron micrographs of dispersed particles of (1) palygorskite from the 6gano mine, ( 2 ) sepiolite from the Karasawa mine. 21 oxygen atoms gives the following formula for a half-unit-cell of "dehydrated

palyqorskite

'I.

IV (Si7.83A10.I 7 ) cs.

00

VI

3+

2+

(All. s8Fea. IqFeo. o 3M92.04)C 3 .

8 4 0 2 ~Cao. 36

The Al/Mg atomic ratio in octahedral site is 0.77, which is somewhat lower than that of the Hanezuru palygorskite.

X-ray powder-diffraction data for the h a n o

material indicate no departure from those of palygorskite given by Bradley (1940). Dispersions of the material give electron micrographs showing laths and bundles of laths.

The laths attain about 2-3 um in length and 0 . 0 5 - 0 . 3

Um

in width (Fig. 2 (11). As will be mentioned later, Imai et al. (1966) already described the occurrence of a clay vein consisting almost entirely of well-crystallized sepiolite (alpha-sepiolite) filling a fault running through the Upper Limestone Member at the Karasawa mine, just 2 km north of the 6gano mine.

This fault is subparallel

to the Ggano No. 10 Fault, along which the 6gano palygorskite has been emplaced. Thus, it was shown that both palygorskite and sepiolite occur along the faults of the same system in the Kuzuu district. Concerning the differences in the physico-chemical environments which controlled the formation of palyqorskite and sepiolite, available information that could be based upon the phase relations in the system MgO-A1203-SiO~-H20is still insufficient.

Imai considered, however, that magnesium-rich and aluminium-

sufficient conditions in the chemical environment would contribute to the formation of palygorskite, whereas magnesium-rich and aluminium-deficient conditions would be favourable to the formation of sepiolite.

Palygorskite and

sepiolite have similar crystal structure, they are, however, somewhat different

217

in chemical compositions.

In palygorskite six-coordinated cations in octahedral

sites are magnesium and aluminium with A1

:

Mg atomic ratio from 2

:

3 to 3 : 2,

whereas in sepiolite they are mainly magnesium (Doelter, 1917). Regarding genesis of the palygorskite and sepiolite in question, Imai et al. (1966) proposed a choice from the following two hypotheses: (1) hydrothermal origin and (2) supergene origin, and they were inclined to prefer hypothesis (1) in spite of the absence of evidence for hydrothermal activity.

They considered

that, whatever the origin of these minerals, the source of magnesium, silica and other components could be attributed to carbonate rocks that are rich in magnesium, such as dolostbne and dolomitic limestone of the Nabeyama Formation (Imai et al., 1966; Minato et al., 1969).

Recently, following the results

obtained by subsequent field work in the district, Imai has inclined to prefer hypothesis (2)-supergene origin for the genesis of the two minerals.

He

suggested that they would be crystallized from low-temperature aqueous solution charged with magnesium, silica and other components produced as a result of ground water circulation within carbonate rocks. Palygorskite associated with metallic mineral deposits In Japan, sepiolites associated with metallic mineral deposits have been known from two localities as will be mentioned later.

An occurrence of paly-

gorskite, however, has been reported from only one locality: the lead-zinc deposits of the Kamioka mine.

Mountain-leather from the Yatate ore deposit of

the Waka Sen-nin mine, Iwate Prefecture, identified as palygorskite in the Sakurai Collection, was revealed to be chrysotile by X-ray and electron diffraction (mixtures of clino- and ortho-chrysotiles). Kamioka (Tochibora)palygorskite.

An occurrence of palygorskite was con-

firmed from the Tochibora ore deposit of the Kamioka mine, Gifu Prefecture by Hattori et al. (1967). Its mode of occurrence in detail, however, is not clear and its identification was made by X-ray diffraction alone.

In the Kamioka

mine, the largest producer of lead-zinc ores in Japan, ore deposits emplaced in a carbonate sequence of the Hida metamorphic belt are of typical skarn type. Judging from the geological environments of the Kamioka ore deposit, it is easily inferred that the Tochibora palygorskite is the product of the latest stage in the course of hydrothrmal lead-zinc mineralization at low temperature. Genesis of Japanese palygorskite Although studies on Japanese palygorskites are still insufficient, concerning their genesis following two origins can be reasonably assumed: (1) supergene origin and (2) hydrothermal origin.

Sakamoto et al. (1975) investigated the

phase transformation of "attapulgite" from Georgia and the Egano palygorskite under hydrothermal condition in the temperature range from 150 to 700 water vapour pressures at 250, 500 and 1000 kg/cm2.

OC

and

They showed that under

pressure of 250 kg/cm2, "attapulgite" is stable below 220

OC

and the 6gano

218 palygorskite below 275

Above these temperatures, these two materials trans-

OC.

form into trioctahedral smectite.

This experimental result suggests low temp-

rature at the time of formation even if an hydrothermal origin is proposed for the Tochibora palygorskite.

SEPIOLITE General remarks Recently occurrences of sepiolites from several localities in Japan have been reported by a number of investigators.

Their mode of occurrence is

variable in comparison with that of palygorskite as mentioned before.

The

Japanese sepiolites in question may be classified broadly into the following four groups on the basis of their modes of occurrence and physico-chemical environments of formation; (1) sepiolites in serpentinites of "serpentine belt", (2) sepiolites associated with metallic mineral deposits, ( 3 ) sepiolites from the "karst region" including those in limestone caves developed there, and (4) sepiolites in Tertiary sediments. Sepiolite in serpentinite Occurrences of sepiolites from serpentinite in "serpentine belt" of regionally metamorphosed terrain have been known in some places in our country. However, detailed studies have been confined to the Yoshikawa sepiolite, which represents the first sepiolite description in our country (Muraoka et al., 1958) and to the Oeyama sepiolites (Muchi et al., 1965; 1966). Yoshikawa sepiolite.

Muraoka et al. (1958) first described sepiolite in

serpentinite at Yoshikawa-mura, Fukuoka Prefecture (Fig. 1).

White waxy

material, occurring as narrow vein-fillings or small massive form ranging from 2 to 3 cm in width in serpentinite which plays the wallrock of the chromite

deposits, was identified as poorly-crystallized sepiolite.

under the micro-

scope, the specimen shows relict fabrics of serpentinite, (indicating it is an alteration product), and consists of aggregates of fibres.

It is colourless

in section and has straight extinction and positive elongation. indices are; a = 1.518, y = 1.528, y

-

a = 0.010.

Refractive

From the results of

chemical analysis (Table 2 ( 4 ) ) , the structural formula after the Nagy-Bradley model was calculated as, Silz.o(Mgs.oFe~.l)Cs.~H~.oO3o(OH)ln.z7.5HzO,

2+

Fe*=Fe

+Fe

3+

In its X-ray diffraction pattern the reflections are not well resolved, indicating its low crystallinity. beta-sepiolite.

The authors identified the material as

As for the genesis of the Yoshikawa sepiolite, the authors

considered that it is of supergene origin, being formed by the replacement of serpentinite by descending meteoric water which invaded the cracks of serpentinite. Eeyama sepiolite (I).

A new occurrence of poorly-crystallized sepiolite was

TABLE

2

Chemical composition of sepiolites and xylotile

55.65

53.98

45.82

49.42

49.76

50.48

52.85

52.15

tr.

0.05

0.99

1.03

0.12

5.48

0.40

2.87

1.47

1.56

0.04

8.23

4.24

2.70

9 .Q2

8.16

54.56

0.05

0.20

0.01

tr. 21.70

0.03

0.20

0.42

1.32

0.34

10.58

10.28

0.17 24.89

22.80

0.04

12.32

0.90

22.03

20.10

20.03

0.06

0.68

7.60

tr.

)O. 12 0.16

53.15

50.74

52.17

0.03

0.20

0.88

0.01

1.66

1.64

1.43

3.02

co.01

0.10

0.79

0.09

21.72

23.74

17.99

22.20

2 2..64

13.20

18.28

0.51

0.20

0.79

0.11

tr.

0.58

46.25

0.74

0.45

0.11

0.01

0.18

n.d.

1.99

0.12

0.06

0.02

0.06

0.73

2.38

0.15

8.34

8.46

9.48

9.99

13.08

9.71

9.23

9.04

9.08

11.40

11.74

8.05

9.38

11.12

11.54

9.41

18.49

14.56

11.50

7.92

12.67

9.01

8.10

9.89

8.55

8.29


0.04

100.62

100.05

99.85

0.01 100.00

97.77

100.05

100.56

100.08

100.11

99.91

99.89

100.18

98.89

(1)Theoretical composition (Erauner and Preisinger. 1956). (2)Sepiolite from Twa C r o w s , Nevada (Post, 1978). 3+ 3+ 2+ 2+ (3)Xylotile. sterzing, Tyrol (CaillZre. 1936): (silo.,sFel.os)Z12.00 (Fe2.69Fe0.0rMn0.0 1Msr.20)26.91032Ca0.05. 14)zepiolite from Yoshikawa-mura, Fukuoka Prefecture-(Muraoka et al., 1958). ( 5 ) O e Y a r M SeplOlite(1) :magnesium sepiolite from the Oeyama mine, Kyoto Prefecture (Muchi et al., 1955). (616eyama sepiolite(I1) :nickeliferous sepiolite from the b y a m mine, Kyoto Prefecture (Muchi et al., 1956). (7)Sepiolite from the Akatani mine, Niigata Prefecture (Imai et al., 1967). (8)Sepiolite from the Karasawa mine, Kuzuu district, Tochigi Prefecture (Imai et al., 1966). (9)Iron-bearing sepiolite from the Kasuqa mine, Gifu Prefecture (Shimusaka et al., 1976). (10)Sepiolite from Miyama, Gifu Prefecture (Nagata and Sakae, 1975). (11)Sepiolite from Itukaichi, Tokyo (Nagata and Sakae. 1975). 112)Iron-bearing sepiolite from Akan-ch6, Hokkaido (Hoe and Hayashi, 1975). (13)Iron-bearing sepiolite from Seikan Strait lknnel (Sakamto et al., 19RO). h,

c W

220

reported by Muchi et al. (1965) from the Geyama nickel mine, Kyoto Prefecture (Fig. 1).

The mine is located approximately at lat. 35"27'N and long. 130'05'E.

The specimen of the 6eyama sepiolite (I) was found in the boulders of serpentinite which were accumulated as talus piles on the northeastern slope of Mt. Akashidake.

Here, the lateritic soils, derived from serpentinite by

weathering,are widely destributed.

The clayey materials, formed by strong

alteration in the soil, contain a small quantity of nickel (0.2-1.5 percent weight NiO), and were mined until 1945.

The material occurs as veinlets 2-3 cm

wide, filling fissurs in massive serpentinite which is altered to form ironrich chlorite of dark greenish-black colour and is often accompanied by minor amounts of magnesite and opaline silica.

The material is white or grey in

colour and consists generally of very compact granules with waxy feeling and greasy lustre.

Through a magnifier it exhibits a mixture of felted fibres and

fine spherical grains.

under the microscope, the material is seen to consist

essentially of bundles of fibres with an extinction parallel to the fibre axis. The fibrous mineral has a refractive index of n = 1.51-1.52. granules are micro-crystalline or amorphous. granules is lower than that of the fibres. show a high content of H20 (Table 2 (5)).

(+)

The interstitial

The refractive index of these

The results of chemical analysis

as compared with that of fibrous-type sepiolite

The calculation of the structural formula on the basis of 32

oxygen atoms in the half-unit-cell of "dehydrated sepiolite" derived from the Brauner-Preisinger model gives the following result: IV VI 2+ (~i11.saAlo.0~)~1~.0o(A~o.ssFeo.loNio.13Mg7.~0)~7.760~2

Electron micrographs of the 6eyama sepiolite (I) show that the morphology of particles is variable.

Some of the micrographs show extremely fine, fibrous

hair-like shapes, while in others very irregular shape, closely similar to amorphous materials can be seen.

It is a noticeable feature that some of the

particles have an apparently flat-rounded form, with fine injections of hairlike materials.

X-ray powder-diffraction data do not deviate essentially from

sepiolite, all reflections, however, are broad and not well resolved, indicating low crystallinity.

From these mineralogical properties, the authors

considered that the specimen might represent an incipient stage of crystallization from beta-sepiolite to alpha-sepiolite.

Summarizing the mode of occurrence

and mineralogical characteristics of the Eeyama sepiolite (I) as noted above, the authors concluded that the mineral was probably formed by the reaction of serpentinite with supergene water, descending along the fissures or cracks in the rocks. zeyama sepiolite (11).

Following the first description of sepiolite from

the ceyama mine, Muchi et al. (1966) reported an occurrence of nickeliferous sepiolite from the same mine.

The light greenish clay resembling "garnierite"

in external appearance and occurring in highly weathered debris, was found in

221

the western part of the mine area, and has been identified as a nickeliferous sepiolite.

In thin section, the material is seen to consist of fibrous

fragments with straight extinction and moderate refractive index of n = 1.551.56.

The result of chemical analysis shows a higher content of H 2 0

(-)

than

that of other fibrous-type sepiolite (Table 2 (6)). The structural formula (0 =

32) from the analysis is calculated as, (Si1 1 . 9 oAl$?o

5)

c 1 1.

2t

q5

(Fe;.

0

?Nio.q iMg7. o 6 ) c 8 .

D0 0 32 ,

Fe*=Fe

tFe

3+

X-ray powder-diffraction data do not deviate significantlyfrom those of common magnesium-sepjolite from Little Cottonwood, Utah given by Brindley (1959); in its X-ray diffraction pattern, the reflections are well resolved, indicating that the crystallinity of this sepiolite is higher than that of the seyama sepiolite (I). As for the genesis of the zeyama sepiolite (II), the authors suggested it to be of supergene origin; a product of reaction between serpentinite and descending meteoric water dissolving salts. Sepiolite associated with metallic mineral deposits Sepiolites in metallic mineral deposits have been found in the Akatani and Waka Sen-nin mines so far.

The hematite deposits of these two mines are

representatives of numerous hematite deposits developed in the so-called "Green-Tuff Region" of Northeast Japan.

These two hematite deposits have long

been believed to be of contact-metasomatic origin (skarn-type deposit), having intimate genetical relation to the Cretaceous granitic rocks.

In recent years,

however, intensive studies by Imai and his colleagues have revealed that these two deposits are of hydrothermal-metasomatic origin, related genetically to Mid-Miocene acidic volcanism (plagiorhyolite) in spite of the widespread occurrence of skarns (e. g . ,

Imai, 1960; 1977).

He considered that skarn

formation and allied weak lead-zinc mineralization were related to the plutonism of Cretaceous granitic rocks, whereas the major hydrothermal iron-copper mineralization was related genetically to plagiorhyolite of Mid-Miocene time. A salient feature of these two ore deposits is the hydrothermal magnesiumenrichment of wallrocks, such as hydrothermal dolomitization of limestones and alteration of the pre-existing skarns. Akatani sepiolite.

An occurrence of well-crystallized sepiolite was reported

by Imai et al. (1967) from the Akatani mine, Niigata Prefecture (Fig. 1).

The

Akatani mine is situated about 40 km east of Niigata City at the southwestern border of the Iide Mountains, approximately at lat. 37O49'N and long. 139"29'E. Hydrothermal alteration of wallrocks is conspicuous over a wide area of the mineralized tracts.

It includes hydrothermal dolomitization of crystalline

limestones and alteration of skarns involving the transformation of clino-

pyroxene and actinolitic hornblende to tremolite and/or talc and that of wollastonite into stevensite (magnesium trioctahedral smectite) and disordered talc, part of which is hydrated.

In addition, chloritization and argillic

222

alteration (formation of dickite, kaolinite and dioctahedral smectite) in plagiorhyolite and hornfelses derived from the Palaeozoic pelitic and psammitic sediments were also recognized. The Akatani sepiolite was found in the west tunnel on the Bawari-zawa 410 m adit level.

Here, the material occurs as fillings of a fissure which cuts both

crystalline limestone and associated skarn masses, and trends in the direction of N60°W with a steep dip to the southwestwards. The sepiolite vein ranges from 2 to 5 cm in width, being weakly foliated parallel to the sharply-defined contact plane with wallrocks. parts.

The vein contains a thin layer of quartz in some

Associated with the vein is a lenticular mass of white clay consisting

predominantly of disordered talc.

The material occurs in the form of macro-

scopic light-weight and flexible fibres.

It consists of pale-greenish fibres

with silky lustre, ranging from 1 to 5 cm in length.

Small amounts of pyrite

and specular hematite are also sparsely disseminated.

Under the microscope,

the sepiolite exhibits an interlacing or random arrangement of fibrous crystals with an extinction parallel to fibre axis.

In some parts of thin sections, a

small amount of talc, which shows the fibrous aggregates interlocking with sepiolite, is also present.

Also,

small grains of quartz and dolomite are

sparsely but homogeneously distributed.

Thus, the material is characterized by

a dolomite-quartz-talc-sepiolite assemblage, arranged in the order of increasing abundance. Refractive indices are; a = 1.508, y = 1.528; y (*

-

0.001), it is optically negative and 2V over X is small.

a

= 0.020

The mineral is

colourless in thin section, but in thick section it is pleochroic with X = pale yellow, Y

.= Zi=

pale-yellowish green.

The result of chemical analysis shows a

relatively high content of manganese (Table 2 ( 7 ) ) .

From the analysis, the

following structural formula ( 0 = 3 2 ) was calculated, IV VI 3+ 2+ 2+ (si1 1.79A10.2 1 ) 1 1 2 o o ( A 1 o o 2Fe0.z 3Feo.i 6mo - 5 6M96.9

-

-

9

17.9 6 0 32

From this, the Akatani sepiolite may be specified as manganous sepiolite.

X-

ray powder-diffraction data agree with those for well-crystallized sepiolite in the literature.

A l l reflections are well resolved, indicating its high

crystallinity. Dispersions of the material give electron micrographs showing elongated fibres or laths and/or bundles of them.

Field relation of its

occurrence site, mode of occurrence and mineralogical properties indicate that the Akatani sepiolite is hypogene and of hydrothermal origin.

The authors

suggest that it was a crystallization product from hydrothermal solution charged with manganese, magnesium, silica etc., moving along the channelways created by fissuring at the latest stage of mineralization at low-temperatures. On the other hand, in the Akatani mine, there is another kind of vein material, dominantly composed of talc, filling the fissures in unaltered crystalline limestone.

The mineral assemblage of the vein material is quartz-

dolomite-talc, and no presence of sepiolite could be confirmed by microscopic

223

jbservation and X-ray diffraction (Imai and Yamazaki, 1967).

Judging from the

feature of wallrock alteratioy, magnesium-bearing mineralization that formed these sepiolite and talc veins would be contemporaneous with magnesium metasomatism repre,sentedby hydrothermal dolomitization of limestones and alterations of skarns proceeded pr.ior to ore deposition, which might correspond to early barren stage in the course of hydrothermal iron-copper mineralization. Our information is still meagre with respect to the physico-chemical environment which controls the formation of sepiolite and talc, it deserves special mention that the talc-bearihg vein is located in the environs of hematite orebodies where magnesium concentration in wallrocks is relatively high as a whole.

The sepiolite vein, in contrast, is located at the place apart from the

main orebodies where the magnesium concentration is relatively low.

The above-

mentioned statement is based upon the modes of distribution of both dolomitization zone and "altered skarn" zone.

The field relation just mentioned

strongly suggests that temperature and chemical nature of solutions have been decisive factors in the formation of these two minerals.

That is to say, talc

formation would be fed from the hydrothermal solution of relatively high temperatures and high concentration of magnesium ascending along the major channelways near the hot centre, whereas sepiolite formation would be fed from solutions of relatively low temperature characterized by the change of initial chemical composition during the circulation along the minor channelway away from the hot centre.

In case of sepiolite formation, the nature of magnesium-

bearing hot water would change to the later phase in which decrease of magnesium and increase of silica, manganese and other components might be expected. While the source of magnesium is undoubtedly deep seated, it seems probable that silica, manganese and iron were derived from the pre-existing skarn minerals rich in manganese such as manganoan ferrosalite during the process of their alteration. Waka Sen-nin sepiolite.

An occurrence of two sepiolites was confirmed by

Imai and Doi from the Waka Sen-nin mine, Iwate Prefecture (Fig. 1) in 1972. Unfortunately, because of the small quantities of these materials, detailed mineralogical studies involving chemical analyses have not been carried out. Therefore, the geological environments of the hematite deposits of this mine, together with a brief description of the materials (unpublished data, m i , 1972) will be given only.

The Waka Sen-nin mine, closed in 1976, is located

about 20 km west of Kitakami City, in the central part of the approximately at lat. 39'18'N

and long. 140°21'E.

&I Mountains,

The-widespread occurrence of

skarns in the mineralized tracts and the structural features of the hematite deposits led previous workers to the belief that they were of contactmetasomatic origin, in genetic connection with the near-by Cretaceous granitic rocks (e. g., Tsuboya, 1950).

It is a noticeable fact, however, that hydro-

thermal alteration associated with ore deposition is marked over an extensive area in the mineralized tracts.

In particular, marked'are hydrothermal

dolomitization of limestones and alteration of skarns represented by the selective conversions of clinopyroxene and actinolitic hornblende into tremolite and/or talc and smectite.

Also, deve'lopment of high-magnesian clay

and mountain-leather of serpentines in the solution cavities of dolomitized limestone is prominent (Imai et al., 1976).

These features of wallrock

alteration are quite similar to those of hematite deposits which were related to the Mid-Miocene plagiorhyolite at the :Akatani mine.

From these facts Imai

(1977) has expressed the opinion that the hematite deposits of the Waka Sen-nin mine are of hydrothermal-metasomatic origin, related genetically to the MidMiocene plagiorhyolite.

The Waka Sen-nin sepiolites may be classified into two

varieties on the basis of their mode of occurrence and mineralogical properties; well-crystallized sepiolite (sepiolite (I)) and poorly-crystallized sepiolite (sepiolite (11)). Material of sepiolite (I) shows pale greenish colour, and consists of sepiolite and antigorite in equal proportion.

It occurs as fillings

in solution cavities of dolomitized limestones on the Shimo-Tohira No. 6 adit level.

In X-ray diffraction patterns, reflections from sepiolite are well

resolved, indicating its high crystallinity, and the powder data do not show significant departures from well crystallized magnesium-sepiolite from the literature.

Dispersions of this material give electron micrographs showing

irregular plate- or lath-like fragments with rectangular outline of antigorite, 1-10 pm long, and fibrous or irregular lath-like fragments of sepiolite with maximum length of 5 Um.

In this study, phase identification of each particle

was made with the aid of selected-area electron diffraction patterns.

Specimens

of sepiolite (11) exhibit pale-brownish colour with a gel-like appearance at the occurrence site in wet condition, that readily changes into fine powder with pale-brownish colour. level.

It was found in the tunnel on the Shimo-Tohira No. 7 adit

Here, it occurs as fillings along the high-angle fissure trending N80"W.

which displays a boundary between "altered skarn" and limestones partially dolomitized.

In its X-ray diffraction pattern, the reflections are broad and

not well resolved indicating its low crystallinity. Powder data agree well with those for poorly-crystallized sepiolite in the literature.

Dispersions of the

material give electron micrographs showing fine fibres some of which have a curled hair-like appearance and other platy particles with extremely irregular outlines.

From the mode of occurrence and mineralogical properties given above,

Imai and Doi suggested that this specimen represented the incipient stage of crystallization from beta-sepiolite to alpha-sepiolite (Doi, 1972). As for the genesis of the Waka Sen-nin sepiolite, two origins of themmay be considered.

Sepiolite (I) in a mixture with antigorite is apparently hypogene

and of hydrothermal origin, whereas in case of sepiolite (II), the assumption

225 of supergene origin seems reasonable, regarding it as the product of precipitation from descending meteoric water. Sepiolite from "karst region" In Japan, there are many "karst regions" where thick carbonate sequences of Palaeozoic and Mesozoic age are exposed widely.

In these carbonate sequences,

thick formations of magnesian carbonate rocks are often

intercalated.

Sepiolites from the "karst regions" including those in limestone caves have been known to occur from a number of localities, detailed mineralogical studies, however, have been restricted to only a few specimens. Karasawa sepiolite.

An occurrence of sepiolite was reported by Imai et al.

(1966) from the Karasawa mine in the KUZUU district, Tochigi Prefecture (Fig. 1).

The Karasawa mine is located about 5 km north of the Kuzuu Railway Station on the TGbu Sano line.

Development of step faults striking nearly E-W with a dip

of 30°-450N is prominent in this mining area.

The Karasawa sepiolite occurs

as fillings along a fault running through the limestones of the Upper Limestone Member, exposed on the cliff about 200 m south of the No. 8 Stop in the open pits.

The sepiolite vein filling the fault ranges from 6 to 10 cm in width.

The contact of the vein with limestone wallrock is sharply defined.

The

material is white in colour with pinkish tint and consists almost entirely of clayey material, but on some occasions it contains lenticular nodules composed essentially of microcrystalline aggregates of quartz.

Under the microscope,

the clayey material is seen to consist principally of fibrous aggregates of sepiolite with some clusters of microcrystalline quartz.

Each fibre tends to

take a preferred orientation with respect to the fibre axis. usually 0.1-0.2 nun long. y - a = 0.017.

The fibres are

The refractive indices are; ct = 1.485, y

The calculation of the structural formula

(0 =

=

1.502,

32) from an

analysis (Table 2 ( 8 ) ) gives, IV 3+ (SilI. 79A10.2 I ) L I Z -o o (Al7f0~Feo. o iMg7.89)c7-96032Cao. 1 2 This formula indicates that the Karasawa sepiolite approximately fulfils the ideal chemical composition of magnesium-sepiolite (Table 2 (l)), with octahedral sites occupied by magnesium ions and the number of cations nearly 8.00. X-ray powder-diffraction data for the material agree well with those of wellcrystallized sepiolite; reflections are well resolved, indicating a high crystallinity.

Dispersions of the clay fraction give electron micrographs

showng single lath and bundles of laths.

The laths attain a maximum length of

about 5 um and a width of about 0.5 I.lm (Fig. 2 ( 2 ) ) .

The above mineralogical

data may indicate that the Karasawa sepiolite represents the alpha-sepiolite with ideal composition of magnesium-sepiolite.

Concerning the genesis of the

Karasawa sepiolite, two hypotheses have been postulated in a previous paper (Imai et al., 1966); ( 1 ) hydrothermal origin and (2) supergene origin.

AS

mentioned before in the preceding section of this paper, however, now the

226

authors are inclined to prefer hypothesis (21, and consider that it might be precipitated from aqueous solutions charged with mpgnesium, silica and other component, derived from meteoric water.

Probably the Karasawa sepiolite re-

presents the final stage of crystallization under low-temperature condition from beta-sepiolite which had primarily been deposited.

The associated micro-

crystalline aggregates of quartz are considered to have been deposited primarily as amorphous opaline silica. Kasuga sepiolite. An occurrence of two varieties of sepiolite, magnesiumsepiolite and iron-bearing sepiolite, was reported by Shimosaka et al. (1976) from the Kasuga mine, Gifu Prefecture (Fig. 1).

The Kasuga mine, a producer

of high-grade dolomite ores is located about 20 km north of Egaki City, approximately at lat. 35'28"

and long. 136'30'E.

The Kasuga sepiolites occur

as cavity-fillings in dolomite marble, closely associated with various minerals such as talc, sepentines, a mica clay mineral, mixed layer mineral of chloritemontmorillonite, amphibole and pyrite.

Sepiolites occur as smooth, chamois

(leather-like and flexible) aggregates of fine particles.

The white material

consists mainly of magnesium-sepiolite, whereas the brown material consists largely of iron-bearing sepiolite representing the intermediate species between magnesium-sepiolite and xylotile-iron rich variety of sepiolite (CaillSre, 1936; Table 2 (2)).

Iron-bearing sepiolite is dark brown (chocolate) in colour

on newly exposed surfaces.

The colour readily turns to brown when exposed to

air, and to dark green when immersed in a solution of vitamine C or hydroxylamine hydrochloride owing to reduction of ferric iron.

Under the microscope,

dolomite crystals are seen to be replaced by aggregates of fine quartz grains the interstices of which are filled with iron-bearing sepiolite.

It is

pleochroic with brown to yellowish brown, and its refractive indices and birefringence ( CL = 1.508, y = 1.525; y - CL = 0.017) are higher than those of magnesium-sepiolite

(

a

=

1.497, y = 1.510; y - CL = 0.013).

Calculation of the

structural formula from an analysis (Table 2 ( 9 ) ) gives a deviation in number of octahedral cations from the ideal value of 8.00 and also a considerable amount of substitution of ferric iron in the tetrahedral sites.

The authors

modified the formula so as to make a smaller deviation by converting some ferric iron into ferrous iron. The resultant structural formula ( 0 = 32) is given by, VI 2+ 2+ Si12.01 ( T i o . ~ ~ A l o . o s F e 1 . 7 5 ~ 9 6 . 0 5 ~ 0 . 0 2 ) ~ 7 - 8 6 0 ~ ~ C a 0 . 0 6 N a O . ~ ~ K 0 - 0 ~ As

for the genesis of the Kasuga sepiolites, field observations by Imai at the

Kasuga mine as well as mode of occurrence and mineral assemblage suggest a hydrothermal origin, by the action of ascending hydrothermal solution, probably resulting from the post-igneous activity of granitic intrusion.

The differences

in physico-chemical environments which controlled the formation of magnesiumsepiolite and iron-bearing sepiolite is not clear in case of the Kasuga materials.

Sepiolite in limestone caves.

Mountain-leather in the fissures of carbonate

rocks including those from limestone caves preserved in the Sakurai collections have been examined by the authors of this paper, and it has been revealed that they are mostly composed of well-crystallized sepiolite. investigation have not been published up-to-date.

The results of these

Recently, however, some

studies of sepiolites have come to appear in some papers as will be mentioned below.

An occurrence of sepiolite mountain-leather was confirmed by Honda et

al. (1971) from Rokando Limestone Cave, Iwate Prefecture.

Subsequently, two

occurrences of sepiolite mountain-leather were reported by Nagata and Sakae (1975) from limestone caves in Miyama, Gifu Prefecture and Itsukaichi, Tokyo (Fig. 1).

The Miyama sepiolite occurs as mountain leather along cracks in

carbonate rocks consisting of calcite and dolomite in limestone caves.

These

are aggregates of fibres of sepiolite, about 2 mm long, and contain small amounts of talc and chlorite.

The result of a chemical analysis (Table 2 (10))

gives the following structural formula ( 0 = 3 2 ) , 3+

3+

(Siii.aiA1~.1iFeo.oe)~12.00(M97.49Feo.37~~7.a~~~~C~0.05

From the structural formula, the results of X-ray diffraction and electron microscopy, the authors identified the Miyama sepiolite as a magnesium-sepiolite belonging to alpha-sepiolite.

The Itsukaichi sepiolite shows a similar mode of

occurrence to that of the Miyama material, and is associated with calcite, talc smectite.

The results of chemical analysis (Table 2 (11)) and X-ray diffraction

showed that the'material was magnesium-sepiolite belonging to alpha-sepiolite. As for the genesis of the Miyama and Itsukaichi sepiolites, the authors suggested a hydrothermal origin. Sepiolite in Tertiary sediments Until recent years, no occurrences of sepiolites have been known in Tertiary sediments of Japan.

Recently, iron-bearing sepiolite has been found in Tertiary

sediments in the north region of the Japanese Island Arc.

It is remarkable that

the type specimens of iron-bearing sepiolite contain also detectable quantities of alkali metals.

This suggests that the physico-chemical environments of their

formation were somewhat different from those of magnesium-sepiolite. Akan sepiolite.

An occurrence of iron-bearing sepiolite was described by

Hoe and Hayashi (1975) from the Charo Formation and the overlying Nuibetsu Formation of Oligocene age in Akan-chE, Hokkaido, North Island (Fig. 1).

The

material of the Akan sepiolite is contained in veins cutting tuffaceous sandstone of the Nuibetsu Formation.

The veins strike N6Oo-7O0W and dip 70°-

75ONE, varying in width from 15 to 150 cm, and consist of two sections with different external appearance; one is massive of dark green colour and the other is white clayey of pale green or white colour.

The white clayey material

readily turns to pale green and then dark green in colour when exposed to air for two or three hours.

Under the microscope, the specimen is seen to consist

22 8 c h i e f l y of i r r e g u l a r aggregates of s e p i o l i t e f i b r e s , 0.1-0.2

nun long.

d i s t r i b u t i o n of chalcedonic s i l i c a and p l a g i o c l a s e ,can be observed.

Sporadic In some

t h i n s e c t i o n , f a i n t r e l i c t f a b r i c s o f igneous rocks a r e recognized, which s e e m t o represent t h e t e x t u r e of p l a g i o c l a s e porph,yrite o c c u r r i n g a s boulders i n t h e No d i s t i n c t pleochroism of t h e mineral i s observed and it has

talus piles.

R e f r a c t i v e i n d i c e s a r e ; c1 = 1.525, y

p o s i t i v e elongation. 0.010.

=

1.535; y -

12 =

The r e s u l t of an a n a l y s i s (Table 2 ( 1 2 ) ) g i v e s t h e following s t r u c t u r a l

formula ( 0 = 321,

IV VI 3+ 2+ 2+ ( S i i i . ~ ~ T i o . o i A ~ o . ~ ~ ) ~(iA~~.o a. oz 6 ~ e i . 5 4 ~ ~ 0 . 3 0 ~ o . i 5 M 9 4 . 4 5 ) ~ 6 . 7 0 ~ 3 2 Cao.igNao.77KO.69 From t h e above formula and X-ray powder-diffraction d a t a t h a t i n d i c a t e high c r y s t a l l i n i t y , t h e authors considered t h a t t h e Akan m a t e r i a l r e p r e s e n t e d an intermediate s p e c i e s between magnesium-sepiolite and x y l o t i l e and corresponded t o alpha-sepiolite.

Concerning g e n e s i s of t h e Akan s e p i o l i t e , t h e authors

suggested t h a t t h e m a t e r i a l was formed by hydrothermal a c t i o n i n dykes of p l a g i o c l a s e p o r p h y r i t e which i n t r u d e d i n t o t u f f a c e o u s sandstone o f t h e Nuibetsu Formation. Seikan s e p i o l i t e .

Quite r e c e n t l y , an occurrence of iron-bearing s e p i o l i t e

was reported by Sakamoto e t a l .

(1980) from t h e Neogene T e r t i a r y p y r o c l a s t i c s

i n t h e p i l o t tunnel of Seikan Undersea Tunnel of t h e Japanese National Railway (Fig. 1 ) . The specimen was found i n t h e p i l o t t u n n e l a t t h e Hokkaido s i d e , where rocks of t h e Kun-nui Formation of Mid-Miocene age a r e widely d i s t r i b u t e d . Here, t h i s formation c o n s i s t s o f l a p i l l i t u f f , t u f f , sandy t u f f and mudstone, and i s i n t r u d e d by small dykes of b a s a l t . the No. tunnel.

The m a t e r i a l occurs a s f i l l i n g s of

11 F a u l t , l o c a t i n g a t about 5000 m from t h e Hokkaido s i d e i n t h i s p i l o t This f a u l t , s t r i k i n g approximately E-W,

dipping 90° with a width of

about 15 cm and throw of more than 100 m, r e p r e s e n t s t h e boundary between t h e t u f f member i n t h e northern s i d e and brown mudstone member i n t h e southern s i d e . The m a t e r i a l shows t h e form of s c a l y aggregates with s i l k y l u s t r e .

Its colour

i s dark green o r o l i v e on newly exposed s u r f a c e , b u t r e a d i l y t u r n s t o brown when exposed t o a i r .

Under t h e microscope, t h e specimen i s seen t o c o n s i s t

almost e n t i r e l y of f i b r o u s aggregates of s e p i o l i t e .

The mineral i s pleochroic

p a l e brown t o yellowish brown and has s t r a i g h t e x t i n c t i o n with r e s p e c t t o t h e f i b r e a x i s and p o s i t i v e elongation.

y = 1.538; y

-

a

= 0.026.

R e f r a c t i v e i n d i c e s a r e ; a = 1.512,

The r e f r a c t i v e i n d i c e s and b i r e f r i n g e n c e a r e higher

than those of magnesium-sepiolite and lower than t h o s e of x y l o t i l e .

Calculation

of t h e s t r u c t u r a l formula ( 0 = 3 2 ) from t h e chemical a n a l y s i s (Table 2 ( 1 3 ) )

shows a d e f i c i e n c y of o c t a h e d r a l c a t i o n s and a considerable amount of s u b s t i t u t i o n of f e r r i c i r o n i n t h e t e t r a h e d r a l s i t e s , a s i n t h e case of t h e Kasuga iron-bearing s e p i o l i t e .

From t h e ESCA s p e c t r a of f r e s h l y powdered and a i r

exposed m a t e r i a l s t o g e t h e r with n o n t r o n i t e , t h e authors suggested t h a t t h i s

229

iron-bearing sepiolite had formed primarily as a ferrous sepiolite and then oxidized in the air-expsed condition. basis of anion unit.

030(OH)4

IV

The modified structural formula on the

is as follows: VJ 2f

2+

( S ~ ~ I . ~ ~ T ~ O - O ~ A (~A l Oo-. iZs F~e 1)-~ 6 5~~ 0Z. 0 .z O M gO6 . i 3 ) ~ 7 . 9 6 0 3 0 ( O H ) 4

-

Cao. o 3Nao. z 5K0 o 4 The above modified formula coincides well with the theoretical formula of sepiolite with respect to the number of cations in both octahedral and tetrahedral sites.

X-ray powder-diffraction data for this material do not show

significant departures from those of alpha-sepiolite in the literature; all reflections are well resolved indicating its high crystallinity.

From the mode

of occurrence of the seikan iron-bearing sepiolite and its mineralogical properties, the authors considered that it might be crystallized from lowtemperature aqueous solution charged with magnesium, iron, silica, etc., moving along the fault under reducing condition.

The solution probably originates

from marine water, since numerous springs along the tunnel have the chemical characteristics of marine water origin (Tatematsu et al., 1982). Genesis of Japanese sepiolite As mentioned before, the Japanese sepiolites show various mode of occurrence, however, from a genetical point of view, their origins may be classified into the following two; (1) hypogene-hydrothermal origin and ( 2 ) supergene origin. Most of the sepiolites have been found in the "karst region" rich in magnesium. Occurrence of this mineral in limestone caves as mountain-leather seems not uncommon, but data on these types of occurrence are still scant.

It is

apparent from the mode of occurrence that favourable physico-chemical environments for their formation might involve extremely high MgO/A1203 ratios, the presence of sufficient silica and alkalies and reducing conditions, at earthsurface temperatures and pressures. In case of the Akatani sepiolite and the Waka Sen-nin sepiolite (I) of hydrothermal origin, field relations indicate low temperatures of formation, probably below 100

OC.

This upper limit temperature is based on the experimental results

of laboratory synthesis, where palygorskite and sepiolite did not appear under hydrothermal conditions and Mumpton and Roy (1956) concluded that they could only form below 100

OC.

Subsequently, sepiolite has been prepared synthetically

at ambient temperature by Siffert and Wey (1962).

Experimental investigation

at earth-surface conditions by Wollast et al. (1968) indicated that the formation of sepiolite would be favoured in environments of hypersalinity, especially those in which waters were silica rich.

Otsuka et al. (1968) investigated the

phase transformation of sepiolite under hydrothermal conditions, and revealed that under water vapour pressure of 250 kg/cm2 the Kuzuu sepiolite was stable below 300 'C, and above this temperature it transformed into "hydrated talc" and talc (>450 " C ) .

These results strongly suggest that temperature conditions are

230 vital factor for sepiolite-talc relations.

SUMMARY AND DISCUSSION

Palygorskite and sepiolite show diverse modes of occurrence and also various external appearances.

Economically profitable deposits of these minerals have

been found in marine, transitional marine and lacustrine sedimentary sequences, occurring interbedded with dolostone, limestone, opaline silica and phosphate throughout the world.

In the Japanese Islands, non-clastic sediments which may

be regarded as evaporites showing lacustrineor lagoonal depositionalenvironments of elevated salinity, have not been recognized in any sedimentary piles.

This might be the reason why large-scale deposits of these minerals are

absent in our country.

Thus, the mode of occurrence and mineralogical proper-

ties of the Japanese palygorskites and sepiolites indicate two possible origins; (1) hypogene-hydrothermal and (2) supergene.

The favourable physico-chemical

environments for the formation of these two minerals would be higher MgO/A1203 ratios and lower temperature under high pH and low redox potential.

Probably,

almost all of these Japanese materials would be the products of direct crystallization from low-temperature aqueous solutions derived from ascending magnesium-bearing hot water or descending meteoric water, a part of which might be brines derived from marine water. The origin of these high-magnesium clays has been much debated by a number of workers and attributed to either alteration of volcanic ash or structural transformation of smectite clays.

Recently, however, the concept of direct cry-

stallization (neo-formation) for their origin has been accepted widely (Millot, 1957; 1962; Isphording, 1973).

In the Akatani mine, high-magnesium clay

composed almost entirely of stevensite may be attributed to alteration of wollastonite skarn, whereas sepiolite occurs as fissure fillings as mentioned before. Palygorskite has already been known to occur as an important constituent of the clay fraction of certain continental-shelf and deep-sea sediments (e. g., Heezen et al., 1965; Hathaway and Sachs, 1966).

In Japan, Aoki et al. (1975)

reported clay mineral compositions for clay fractions from about 350 specimens of surface sediments collected from several seas and oceans, especially in the environs of Japanese Island Arc, however, they were unable to confirm the presence of either palygorskite or sepiolite.

REFERENCES Aoki, S., Oinuma, K. and Kobayashi, K. (1975) Study of clay minerals in recent marine sediments (in Japanese with English abstr.). In: K. Henmi (Editor), Contrib. to Clay Mineralogy, 161-166. Bradley, W. F. (1940) Structure of attapulgite. Am. Mineral., 25:405-410.

231 Brauner, K. and P r e i s i n g e r , A. (1956) S t r u k t u r und E n t s t e h u n g d e s S e p i o l i t h s . Tschennaps M i n e r a l . P e t r o g r . M i t t . , 6:120-140. B r i n d l e y , G. W. (1959) X-ray and e l e c t r o n d i f f r a c t i o n d a t a f o r s e p i o l i t e . Am. M i n e r a l . , 44:495-500. C a i l l s r e , S . (1936) Thermal s t u d i e s . B u l l . SOC. f r a n q . MinGr., 59:353-374. Doelter, C. (1917) Handbuch d e r Mineralchemie, S t e i n k o p f f , Dresden. D o i , S . (1972) Geology and o r e d e p o s i t s i n t h e Waka Sen-nin mine area, Iwate P r e f e c t u r e ( m a n u s c r i p t i n J a p a n e s e w i t h E n g l i s h abstr.). Master T h e s i s No. T7004001, G r a d u a t e Sch. S c i . and Eng., Waseda Univ., 1-89. Hathaway, J. and S a c h s , P. (1965) S e p i o l i t e and c l i n o p t i l o l i t e from t h e midAm. M i n e r a l . , 50:852-867. A t l a n t i c Rige. H a t t o r i , N . , Minato, H . and Watanabe, T. (1967) P a l y g o r s k i t e from Tochibora, 73:85. Kamioka mine (abstr. i n J a p a n e s e ) . J o u r . Geol. SOC. J a p a n . , Hayashi, H . , O t s u k a , R. and I m a i , N . (1969) I n f r a r e d s t u d y o f s e p i o l i t e and p a l y g o r s k i t e on h e a t i n g . Am. M i n e r a l . , 53:1613-1624. Heezen, B . C., N e s t e r o f f , W. D. e t S a b a t i e r , M. G . (1965) Decouverte d ' a t t a p u l g i t e d a n s l e s s 6 d i m e n t s p r o f o n d s du g o l f e d'Aden e t de l a m e r Rouge. C. R. Acad. S c i . P a r i s , 260:5819-5821. Hoe, S. G. and Hayashi, M . (1975) A new o c c u r r e n c e of f e r r i f e r o u s s e p i o l i t e from t h e Akan-cho, e a s t e r n Hokkaido, Japan ( i n J a p a n e s e w i t h E n g l i s h a b s t r . ) . J o u r . J a p a n e s e ASSOC. Miner. P e t r o l o g . Econ. G e o l . , 70:440-446. Honda, S . and Members of Caving Group o f A k i t a U n i v e r s i t y (1971) F i n d i n g o f s e p i o l i t e m o u n t a i n - l e a t h e r from l i m e s t o n e c a v e ( s h o r t comm. i n J a p a n e s e ) . J o u r . Geol. SOC. J a p a n , 77:397-398. Imai, N . (1960) G e n e s i s o f t h e h e m a t i t e d e p o s i t s i n t h e I n n e r Zone o f Northe a s t e r n Japan. J o u r . Fac. S c i . N i i g a t a Univ., S e r i e s 11, 3:205-256. I m a i , N . , O t s u k a , R . , Nakamura, T. and I n o u e , H . (1966) A new o c c u r r e n c e o f w e l l - c r y s t a l l i z e d s e p i o l i t e from t h e KUZUU d i s t r i c t , T o c h i g i P r e f e c t u r e , C e n t r a l J a p a n ( i n J a p a n e s e w i t h E n g l i s h abstr.). J o u r . Clay S c i . SOC. J a p a n , 6: 30-40. I m a i , N., O t s u k a , R. and Nakamura, T. (1967) An o c c u r r e n c e of w e l l - c r y s t a l l i z e d s e p i o l i t e from t h e A k a t a n i mine, N i i g a t a P r e f e c t u r e , N o r t h e a s t e r n Japan. J o u r . J a p a n e s e A s s o c . Miner. P e t r o l o g . Econ. G e o l . , 57:39-56. I m a i , N. and Yamazaki, S. (1967) Hydrothermal d o l o m i t e - r o c k s a s s o c i a t e d w i t h h e m a t i t e d e p o s i t s o f t h e A k a t a n i mine, N i i g a t a P r e f e c t u r e , J a p a n . Memo. Sch. S c i . and Eng., Waseda Univ., 3 1 : l l - 6 3 . Imai, N . , Otsuka, R . , Kashide, H. and H a y a s h i , H. (1969) Dehydration o f p a l y g o r s k i t e and s e p i o l i t e from t h e Kuzuu d i s t r i c t , T o c h i g i P r e f . , C e n t r a l Japan. 1n:L. H e l l e r ( E d i t o r ) , P r o c . I n t e r n a t ' l Clay Conf., Tokyo, 1:99-108. I m a i , N . , O t s u k a , R., Honda, S., I s o d a , N. and S u z u k i , S. (1976) S e r p e n t i n e s a s s o c i a t e d w i t h h y d r o t h e r m a l d o l o m i t e - r o c k a t t h e Waka Sen-nin mine, I w a t e Prefecture. J o u r . J a p a n e s e ASSOC. Miner. P e t r o l o g . Econ. G e o l . , 71:339-359. I m a i , N . (1977) G e n e s i s o f t h e i r o n - c o p p e r d e p o s i t s o f t h e Waka Sen-nin mine, I w a t e Prefecture ( i n Japanese). I n : I . Hamashima ( E d i t o r ) , S t u d i e s on t h e c o n t a c t metasomatic d e p o s i t s , B. 1-12. I s p h o r d i n g , W. C. (1973) D i s c u s s i o n o f t h e o c c u r r e n c e and o r i g i n o f s e d i m e n t a r y p a l y g o r s k i t e - s e p i o l i t e d e p o s i t s . C l a y s and C l a y M i n e r a l s , 21:391-401. M i l l o t , G. (1957) JXs c y c l e s s s d i m e n t a i r e s e t d e t r o i s modes d e s g d i m e n t a t i o n argileuse. C. R. Acad. S c i . F r . , 244:2536-2539. M i l l o t , G. (1962) C r y s t a l l i n e n e o f o r m a t i o n o f c l a y s and s i l i c a . P h y s i c a l SCi. Some r e c e n t advances i n F r a n c e and t h e U n i t e d s t a t e s . N . Y . Univ. P r e s s , 159-169. Minato, H. (1966) P a l y g o r s k i t e from Hanezuru, KUZUU, T o c h i g i P r e f e c t u r e , J a p a n ( i n J a p a n e s e w i t h E n g l i s h a b s t r . ) . J o u r . C l a y S c i . SOC. J a p a n , 6:22-28. Minato, H . , I m a i , N. and Otsuka, R. (1969) P a l y g o r s k i t e from t h e 6gano mine, Tochigi P r e f e c t u r e , C e n t r a l Japan. J o u r . J a p a n e s e Assoc. Miner. P e t r o l o g . Econ. Geol., 61:125-139. Muchi, M., Hoshino, Y. and F u r u s a t o , I. (1965) P o o r l y - c r y s t a l l i z e d s e p i o l i t e from t h e 6eyama n i c k e l mine, Kaya-cho, Yosa-gun, Kyoto P r e f e c t u r e . Jour. J a p a n e s e ASSOC. Miner. P e t r o l o g . Econ. G e o l . , 53:39-54.

232 Muchi, M., Hoshino, Y. and Furusato, I. (1966)A nickeliferous sepiolite from the Oeyama nickel mine, Kyoto Prefecture, Japan. Jour. Japanese ASSOC. Miner. Petrolog. Econ. Geol., 56:93-106. Mumpton, F. and Roy, R. (1958) New data on sepiolite and palygorskite. Clays and Clay Minerals, 5:136-143. Muraoka, H., Minato, H., Takano, Y. and Okamoto. Y. (1958) Sepiolite from Yoshikawa-mura, Fukuoka Prefecture (in Japanese). Jour. Miner. SOC. Japan, 3:381-387. Nagata, H., Shimoda, S. and Sudo, T. (1973) On dehydration of bound water of sepiolite. Clays and Clay Minerals, 22:285-293. Nagata, H. and Sakae, T. (1975) New occurrence of sepiolites from the limestone caves at Gifu and Tokyo, Japan (in Japanese with English abstr.). In: K. Henmi (Editor), Contrib. to Clay Minesalogy, 128-133. Otsuka, R., Hayashi, H. and Shimoda, S. (1968) Infrared absorption spectra of sepiolite and palygorskite. Memo. Sch. Sci. and Eng., Waseda Univ., 32:13-24. Otsuka, R., Hayashi, H. and Imai, N. (1970) Dehydration of sepiolite and palyqorskite, with special reference to the behaviour of bound water (in Japanese with English abstr.). Bull. Sci. Eng. Res. Lab., Waseda Univ., 47:56-63. Otsuka, R., Sakamoto, T. and Hara, Y. (1974) Phase transformation of sepiolite under hydrothermal conditions (in Japanese with English abstr.). Jour. Clay Sci. SOC. Japan, 14:8-19. Post, J. L. (1978) Sepiolite deposits of the Las Vegas, Nevada Area. Clays and Clay Minerals, 26:58-64. Sakamoto, T., Otsuka, R. and Takizawa, A . (1975) Phase transformation of attapulgite and sepiolite under hydrothermal conditions (in Japanese with English abstr.). In: K. Henmi (Editor), Contrib. to Clay Mineralogy, 138-144. Sakamoto, T., Suzuki, S., Tatematsu, H. and Otsuka, R. (1980) Iron-sepiolite from the Seikan Tunnel, Japan. Jour. Japanese ASSOC. Miner. Petrolog. Econ. Geol., 75:164-171. Shimosaka, K., Kawano, M. and Sudo, T. (1976) New occurrence and mineralogical properties of iron sepiolite. Clay Sci., 5:31-41. Siffert, B. and Wey, R. (1962) SynthSse d'une sgpiolite 2 tempgrature ordinaire. C. R. Acad. Sci. Fr., 254:1460-1462. Tatematsu, H., Sakamoto, T. and Otsuka, R. (1982) The correlation between exchangeable cation compositions of smectites and the quarity of ambient seepage waters from the Seikan Undersea Tunnel (1) and (2). (in Japanese) Jour. Clay Sci. SOC. Japan, 22:49-54, 22:169-174. Tsuboya, K. (1950) A classification of primary metallic ore deposits of Japan and their regional geological characteristics (in Japanese). Bull. Physiograph. Sci. Res. Inst., Univ. of Tokyo, 4:57-64, 5:16-21, 6:l-5. Wollast, R., Mackenzie, F. and Bricker, 0. (1968) Experimental precipitation and genesis of sepiolite at earth-surface conditions. Am. Mineral., 53 :1645-1661.

233

PALYGORSKITE AND SEPIOLITE DEPOSITS I N THE USSR AND THEIR USES OVCHARENKO F . D.

,

KUKOVSKY Ye. G . (+)

("Institute o f C o l l o i d Chemistry and Chemistry o f Water, Academy o f S c i e n c e s o f t h e Ukrainian SSR, Kiev. ( + ) I n s t i t u t e o f Geochemistry and P h y s i c s o f Mi n er al s, Academy o f .Sciences o f t h e Ukrainian SSR, Kiev. INTRODUCTION

S o v i e t r e s e a r c h e r s such as Fersman (1955), c a l l p a l y g o r s k i t e a Russian m i n e r a l , s i n c e b o t h mountain-skin and mountain-cork were mentioned as e a r l y as Up t o

t h e o u t s e t o f t h e 1 8 t h c e n t u r y , m o s tl y i n c on n ect i o n w i t h a s b e s t o s .

1860, when mountain-skin d e p o s i t s were p r o s pect ed i n t h e Palygorsk D i v i si o n Mine n e a r t h e Popovka R iv e r , Perm P r o v in c e , t h i s u n u su al m i n er al was assumed t o r e p r e s e n t a v a r i e t y of a s b e s t o s .

The v e r y f i r s t d e s c r i p t i o n s o f t h i s i n t e r -

woven-fiber m i n e r a l i n d i c a t e d a high alumina c o n t e n t .

The chemical composition

was used t o show t h a t t h e s e materials, named ' p a l y g o r s k i t e ' a f t e r t h e l o c a t i o n o f t h e d e p o s i t s , could be c o n s id e r e d as a new group o f m i n e r a l s .

The p e c u l i a r

p r o p e r t i e s o f t h i s aluminum/magnesium h y d r o s i l i c a t e group o f m i n e r a l s , which are s u b s t a n t i a l l y d i f f e r e n t from t h o s e o f t h e a s b e s t o s group, were e s t a b l i s h e d

by l a t e r d e s c r i p t i o n s o f similar material found n e a r t h e Volga. Up t o 1960, r e p o r t e d p a l y g o r s k i t e o c c u r r e n ces, i n t h e form o f mountain-skin and m o u n t ai n - cor k - li k e accumulations o v e r c r y s t a l l i n e rocks as well a s i n li m es t o n e and t h i n c l a y l a y e r d e p o s i t s were o f no economic v a l u e .

Such

f o r m at i o n s o f p a l y g o r s k i t e o c c u r r e n c e s a r e common i n a l l r e g i o n s o f t h e USSR. They are known from t h e c e n t r a l r e g i o n s o f t h e European p a r t o f t h e USSR n e a r t h e Volga, i n Crimea, i n T r a n s c a u c a s i a n r e g i o n s , i n C e n t r a l Asia, i n T r a n s b a i k a l r e g i o n s , i n t h e Urals and J a k u t s k ASSR. Kukovsky i n 1960 r e p o r t e d t h e p r o s p e c t i n g o f Ukrainian p a l y g o r s k i t e c l a y d e p o s i t s ; t h e s e f i r s t major d e p o s i t s i n E u r a s i a are analogous b o t h i n composit i o n and p r o p e r t i e s t o a t t a p u l g i t e i n t h e USA.

Some y e a r s l a t e r , major

p a l y g o r s k i t e d e p o s i t s were a l s o r e p o r t e d i n C e n t r a l A si a.

Recent p r o s p e c t i n g

i n d i c a t e d t h e commercial v a l u e o f some o f t h e p a l y g o r s k i t e d e p o s i t s , prompting the necessity t o generalize available geological data.

234

PALYGORSKITE AND SEPIOLITE DEPOSITS I N THE USSR Z a i n u l l i n (1977) undertook t h e f i r s t a tt e m p t t o c l a s s i f y t h e p a l y g o r s k i t e d e p o s i t s i n t h e USSR. The m a j o r i t y o f p a l y g o r s k i t e d e p o s i t s are g e n e t i c a l l y l i n k e d w i t h exogenous p r o c e s s e s : p h y s i c a l w e a th e r i n g o f c r y s t a l l i n e - r o c k s and s e d i m e n t a t i o n o f t h e a e o l i a n weat h er i n g p r o d u c t s i n a l k a l i n e environments o f i s o l a t e d sed i m en t at i o n b a s i n s . A s m a l l p a r t o f t h e p a l y g o r s k i t e o c cu r r en ces r e s u l t e d a l s o from hydrothermal p r o c e s s e s and are l i n k e d w i t h some s k a r n p o l y m et al o r e d e p o s i t s of t h e T r a n s b a i k a l , T r a n s c a u c a s ia n , and C e n t r a l Asian r e g i o n s . p a l y g o r s k i t e makes up v e i n s , p o c k e t s and c r u s t s .

I n above c a s e s ,

A l l these manifestations

are o n l y m i n e r a l o g i c a l l y s i g n i f i c a n t . P a l y g o r s k i t e m a n i f e s t a t i o n s a s s o c i a t e d w i t h c r y s t a l l i n e rock w eat h er i n g are w id el y s p r e a d o v e r t h e t e r r i t o r y o f t h e USSR.

They a r e c h i e f l y i n t h e form o f

v a s t i n t e r l a y e r s o f mountain-skin i n g r u s s o f weathered amphibole d i o r i t e n e a r Kurtsy V i l l a g e , n o t f a r from Symferopol (Crimea), i n weathered b a s a l t i c and g r a n i t e c r u s t s i n Volyn and Zhitomir D i s t r i c t ( t h e U k r ai n e) , i n t h e weathered c r u s t o f s e r i c i t e and p h l o g o p i t e s h a l e s w i t h i n t h e Kursk Magnetic Anomaly, i n t h e weathered c r u s t o f s e r p e n t i n i z e d d o l o m i te i n Kurganshinkan ( U zb ek i st an ) , and i n t h e weathered c r u s t o f s e r p e n t i n e rock i n t h e Urals.

A l l t h e s e o ccu r -

re n ces are o f l i t t l e o r no economic v a l u e . The l a r g e

group o f s e d i m e n ta r y p a l y g o r s k i t e o ccu r r en ces i s l i n k ed w i t h

P al eo zo i c l i m es t o n e and c l a y r o c k s o f t h e Russian P l a t f o r m , e s p e c i a l l y w i t h c a r b o n at e m i n er a ls i n t h e Moscow syneclise, w i t h Upper Permian rocks n e a r t h e Volga, Tatar, ASSR.

I n t h e Devonian P e r i o d , p a l y g o r s k i t e i s a s s o c i a t e d w i t h

o v e r s a l t l a y e r s ( S ta r o o b i n s k Region, B y e lo r u ssi a) e t c .

I n t h e USSR, e s p e c i a l l y

i n i t s European p a r t , t h e r e are a g r e a t many such p a l y g o r s k i t e o ccu r r en ces. O f a l l t h e p a l y g o r s k i t e assemblages i n t h e Ukraine, t h e Cherkassk b e n t o n i t e

and p a l y g o r s k i t e d e p o s i t s are o f major i n t e r e s t (Ovcharenko e t a l . , 1967) ( F i g s . 1 and 2 ) .

I n i t i a l r e s e a r c h i n d i c a t e d t h a t t h e producing t h i c k n e s s o f

the clay deposits consists of f i v e separate lithological layers. from t o p : 1 2

-

-

c a l c a r e o u s hydromicaceous m o n t m o r i l l o n i t e c l a y (up t o 8 m t h i c k ) ;

b e n t o n i t i c c l a y (up t o 8 m t h i c k ) ; 3

Fig. 3 ) ; 4

-

They are

-

p a l y g o r s k i t e c l a y (up t o 2m

,

montmorillonite/palygorskite c l a y (up t o 1.5m); and 5 - green For t h e time b e i n g t h e f i r s t

mo n t m o r i l l o n i t e hydromicaceous c l a y (up t o 2m).

l a y e r of t h e Sarmatian (Miocene) and t h e f i f t h l a y e r o f t h e Kharkovian (Oligocene) are excluded from t h e producing t h i c k n e s s . o f t h e Znd, 3 r d and 4 t h l a y e r s (Miocene). about 15 y e a r s .

S e l e c t i v e use i s made

Industry uses these deposits f o r

235

K L A J A CERKOV

Fig. 1.

Schematic map of Cherkassk palygorskite deposit region.

N

w c7

.

Fig. 2 .

Schematic s e c t i o n a l o n g l i n e 1-1 o f Cherkassk d e p o s i t .

237

G e n e t i c a l l y t h e producing t h i c k n e s s i s c o n s i d e r e d chemogenic and s e d i mentary.

The f o r m a t i o n o f t h e p a l y g o r s k i t e i s e x p l a i n e d by t h e t r a n s f o r m a t i o n

of t h e e s s e n t i a l l y c l a s t i c sediments i n i s o l a t e d l o c a l sea b a s i n , w i t h a s p e c i f i c a l k a l i n e environment (Kukovsky and Ostrovskaya, 1961).

Lomova

(1979) however s u g g e s t s t h a t p a l y g o r s k i t e was formed as a r e s u l t o f t h e decomposition of a l k a l i n e b a s a l t o i d v o l c a n o c l a s t i c materials d u r i n g t h e p r o c e s s of d i a g e n e s i s and e a r l y e p i g e n e s i s i n t h e p r e s e n c e o f t h e r m a l l y mineralized solutions. A number of p a l y g o r s k i t e assemblages o f i n d u s t r i a l v a l u e , a s s o c i a t e d with

Cretaceous and Neogene t e r r i g e n o u s d e p o s i t s were p r o s p e c t e d i n Uzbekistan (Zakirov, 1974). and hydromica.

Palygorskite i n clay deposi t s associ at es with montmorillonite G e n e t i c a l l y such m i n e r a l i z a t i o n p r o c e s s e s a r e caused by terri-

genous m a t e r i a l d e p o s i t i o n i n normal sea water o r c o n t i n e n t a l s e d i m e n t a t i o n b a s i n s t h a t c o n t a i n high s i l i c a and magnesium c o n c e n t r a t i o n s . S e p i o l i t e o c c u r r e n c e s a r e v e r y r a r e w i t h i n t h e t e r r i t o r y o f t h e USSR. As y e t nobody p r o s p e c t e d s e p i o l i t e c l a y d e p o s i t s similar t o t h e p a l y g o r s k i t e

deposits.

S e p i o l i t e accumulations o f v a r i o u s sizes are a s s o c i a t e d w i t h wind-

eroded s e r p e n t i n i t e c o r e s n e a r t h e Ufaley n i c k e l d e p o s i t s i n t h e Urals, i n Dzhezda d e p o s i t s (Karsakpay F a u l t s ) , and n e a r t h e Talnakh Mine F i e l d ( N o r i l s k group o f c o p p e r / n i c k e l d e p o s i t s ) .

Sedimentary t y p e s e p i o l i t e s may b e

found i n C a r b o n i f e r o u s d o l o m i t e d e p o s i t i o n s on t h e Russian P l a t f o r m n e a r Krasnaya Polyana and i n d o l o m i t e s i l t s i n Balkhash Lake (Rateyev, 1964). G e o l o g i c a l d a t a a n a l y s i s p e r m i t s us t o c o n s i d e r b o t h p a l y g o r s k i t e and s e p i o l i t e t o be t h e p r o d u c t s o f h i g h l y s p e c i f i c m i n e r a l i z a t i o n p r o c e s s e s . M i n e r a l o g i c a l d a t a g i v e moreover proof of t h e p r e v a i l i n g d i r e c t g e n e t i c a l a s s o c i a t i o n o f b o t h p a l y g o r s k i t e and s e p i o l i t e w i t h c h a i n and r i b b o n s i l i c a t e s . One might be l e d t o conclude t h a t both pyroxenes and amphiboles, i . e . r o c k forming s i l i c a t e s o f b a s i c and u l t r a b a s i c r o c k s , a r e p r e c u r s o r s o f b o t h p a l y g o r s k i t e and s e p i o l i t e .

C o n s i d e r i n g t h a t s o l u b l e aluminum i s n o t l i k e l y

t o b e p r e s e n t i n t h e systems f a v o r a b l e f o r p a l y g o r s k i t e c r y s t a l l i z a t i o n through s y n t h e s i s from s o l u t i o n , t r a n s f o r m a t i o n mechanisms, such as t h o s e proposed f o r t h e Cherkassk d e p o s i t s , t h a t are s e c u r e l y i s o l a t e d from p o s s i b l e hydrothermal s o u r c e s by c o n s i d e r a b l e p e r i o d s o f s e d i m e n t a t i o n and c r u s t forming (Kharkov l a y e r ; Chalk/Paleogenic w e a t h e r i n g o f c r y s t a l l i n e rock) c o n s t i t u t e a f a r more s u b s t a n t i a l b a s i s f o r approaching t h e g e n e t i c problems

of p a l y g o r s k i t e f o r m a t i o n . From t h e p o i n t of view o f c r y s t a l l o c h e m i s t r y , t h e l a y e r - r i b b o n s t r u c t u r e o f b o t h p a l y g o r s k i t e and s e p i o l i t e can be c o n s i d e r e d as m e t a s t a b l e and s h o u l d be l o g i c a l l y p l a c e d between t h e c h a i n / r i b b o n s t r u c t u r e s of pyroxenes and amphiboles and t h e l a y e r s t r u c t u r e s of s m e c t i t e s .

The t h r e e - c h a i n s e p i o l i t e

238

Fig. 3.

Electron micrograph of palygorskite particles: a.

mountain-skin palygorskite from Crimea, near Simferopol;

b.

palygorskite clay from Cherkassk deposit.

239 s t r u c t u r e i s less s t a b l e t h a n t h e two-chain p a l y g o r s k i t e s t r u c t u r e , and i s t h e r e f o r e c l o s e r t o t h e m o n tm o r il lo n i te l a y e r s t r u c t u r e , a f a c t t h a t i s reflected i n the peculiarities of s e p i o l i t e diffraction patterns.

The sub-

s t a n t i a l l y rarer s e p i o l i t e m a n i f e s t a t i o n s , a s compared w i t h p a l y g o r s k i t e o n es, may be e x p l a i n e d by t h e m e t a s t a b i l i t y o f t h e s e p i o l i t e s t r u c t u r e . PROPERTIES AND USES P h y s i c a l and chemical p r o p e r t i e s o f p a l y g o r s k i t e were d i s c u s s e d i n d e t a i l i n Ovcharenko :et a l . (1967).

Some o f t h e main s u r f a c e p r o p e r t i e s a r e :

a p o l y d i s p e r s e s t r u c t u r e , w i t h 300

8

e f f e c t i v e pore radia, 6 . 4 x 3.7

8

z e o l i t e ch an n e l s , 40-80 1 i n t e r m e d i a t e p o r e s , and about 20 8 micropores. The s p e c i f i c s u r f a c e s o f t h e i n n e r c h a n n e l s and p o r e s make up 50% o f t h e t o t a l s u r f a c e (224 m2/g), c a l c u l a t e d by low t e m p er at u r e a d s o r p t i o n o f n i t r o g e n . P a l y g o r s k i t e s u r f a c e m o d i f i c a t i o n by t h e s a l t s o f q u a t e r n a r y ammonium compourids showed t h a t o n l y o u t e r s u r f a c e s and l a r g e p o r e s t a k e p a r t i n t h e h y d r o p h o b i zat i o n p r o c e s s .

This p e c u l i a r i t y o f t h e s t r u c t u r e p er m i t s t o use

t h e m i n er al as a s e l e c t i v e s o r b e n t and s t a t i o n a r y phase i n gas chromatography. Taking i n t o account t h a t i s o - and c y c l o - p a r a f f i n a d s o r p t i o n h e a t on p al y g o r s k i t e i s somewhat lower t h a n i n t h e c a s e o f n - al k an es,

t h e m i n er al i n i t s

n a t u r a l form p r e s e n t s h i g h s e l e c t i v i t y towards t h e normal p a r a f f i n s .

Sorption

s e l e c t a n c e (and hence s e p a r a t i o n ) rises w i t h t h e m o l ecu l ar mass o f n - al k an e. The c a l c u l a t e d increment o f a d s o r p t i o n h e a t i n n - p a r a f f i n homologous series (2.1

-

2.4 Cal./mol)

exceeds t h e same f o r bo t h s i l i c a g e l s and s i l i c a - a l u m i n a

g e l s and approaches t h a t f o r z e o l i t e s .

I t p r o v es t h a t z e o l i t e channels and

micropores of t h e p a l y g o r s k i t e p a r t i c i p a t e i n gas chromatographic s e p a r a t i o n . Aromatic and o l e f i n i c hydrocarbons s e p a r a t i o n on p a l y g o r s k i t e i s hampered by h i g h energy a d s o r p t i o n c e n t e r s on i t s s u r f a c e and may b e r e a l i z e d only a f t e r ion-exchange s u r f a c e m o d if i c a ti o n by l a r g e - s i z e o r g a n i c c a t i o n s ( l i k e

t h e q u a t e r n a r y ammonium b a s e s a l t s ) .

A t t h e same time exchange r e a c t i o n s

w i t h i n o r g a n i c c a t i o n s have l i t t l e i n f l u e n c e upon t h e h y d r o p h i l i c n a t u r e . So, f o r example, K-form w e t t i n g h e a t i s o n l y 1.5% below t h a t o f Ca-form.

This f a c t i s ex p l a i n e d by t h e c r y s t a l l o c h e m i c a l s t r u c t u r e o f t h e l a y e r ribbon minerals.

I t was used as a b a s i s f o r t h e s a l t r e s i s t a n t d i s p e r s i o n s with

developed c o a g u l a t i n g / t h i x o t r o p i c s t r u c t u r e s ( K r u g l i t sk y e t a l . , 1974). M i n er al i zed p a l y g o r s k i t e s u s p e n s io n s are c h a r a c t e r i z e d by s t a b i l i t y

- 0.002 g / c 3 ) w h i le s u s p e n s io n s w i th c o n c e n t r a t i o n of 14.5% show h i g h e l a s t i c i t y , p l a s t i c i t y and real r e l a x a t i o n p e r i o d . P a l y g o r s k i t e d i s p e r s i o n s (0.001

b eh av i o r under e l e v a t e d te m p e r a t u r e and p r e s s u r e c o n d i t i o n s was s t u d i e d i n c o n n ect i o n w i t h t h e u s e o f f l u s h i n g f l u i d f o r b o t h deep and superdeep d r i l l i n g . X-ray s t r u c t u r a l a n a l y s i s of a 10% d i s p e r s i o n , f o l l o w i n g t h e hydrothermal

2 40

t r e a t m e n t ( t em p e r a t u r e - - 35OOC; p r e s s u r e

-

169 atm.; time

b e s i d e s t h e r e f l e c t i o n t y p i c a l f o r p a l y g o r s k i t e (10.59 15.6

8,

8),

-

3 h) showed,

a d i s t i n c t peak a t

c h a r a c t e r i s t i c f o r smectite.

S t a b l e co ag u l a t o r y s p a c e n e t s develop under lower c o n c e n t r a t i o n s o f t h e s o l i d p h as e, due t o t h e p r e s e n c e o f two s t r u c t u r a l l y d i f f e r e n t m i n e r a l s i n t h e dispersion.

A s a r e s u l t o f cut-down p a r t i c l e i n t e r a c t i o n energy, t h ey have a

lower modulus o f e l a s t i c i t y i n s h e a r .

Such d i s p e r s i o n s m ai n t ai n h i g h s t a b i l i t y

i n t h e p r es en ce of v a r i o u s w e ig h t in g m a t e r i a l s , p e r m i t t i n g t o u s e them i n d r i l l i n g under complicated c o n d i t i o n s , e s p e c i a l l y f b r t h e d r i l l i n g o f s a l t deposit

.

Due t o high water a d s o r p t i o n p r o p e r t i e s , p a l y g o r s k i t e i s used a s a d d i t i v e i n grouting mortar for t h e prevention o f s l a k i n g . d i s p e r s i o n s have a moderate d e n s i t y (1.5 tolerable strength.

-

Such cement

-

palygorskite

1 . 6 g / c 3 ) , good s p r e a d i n g , and

A t 150°C t h e i r s t r e n g t h i n c r e a s e s ,

G e n e t i c a l m i x tu r e s o f p a l y g o r s k i t e and m o n t m o r i l l o n i t e have a high s e l e c t i v i t y f a c t o r towards c e r t a i n components o f petroleum p r o d u c t s .

Th i s p r o -

p e r t y is used i n p u r i f y i n g b e n z o l from u n l i m i t e d hydrocarbons, as well as n a t u r a l gas from m o is t u r e and condensate.

A s compared w i t h t h e known ad so r -

b e n t s o f ' B a n a t i ' F i r m and Rumanian a c t i v i z e d s o r b e n t s , y i e l d i n g 2 . 3 g/g p u r i f i e d b en zo l , m o n t m o r i ll o n it e and p a l y g o r s k i t e g e n e t i c m i x t u r es from Cherkassk d e p o s i t s y i e l d 6 . 2 g/g b e n z o l (Ovcharenko e t a l . , 1972). Removal o f u n l i m i t e d hydrocarbons from b e n z o l , and n a t u r a l gas d e s i c c a t i o n / p u r i f i c a t i o n processes may s e r v e as examples of s u c c e s s f u l u t i l i z a t i o n o f t h e f o u r t h h o r i zo n c l a y s from Cherkassk d e p o s i t .

T r a d i t i o n a l p et r o ch em i cal

p u r i f i c a t i o n p r o c e s s e s o f hydrocarbon b e n z o l f r a c t i o n s from u n l i m i t e d a s s o c i a t e d compounds, cannot y i e l d h i g h - q u a l i t y p u r i f i e d p r o d u c t s .

By

a d s o r p t i o n - p u r i f i c a t i o n w i t h t h e h e l p o f a d s o r b en t based upon t h e f o u r t h l a y e r o f t h e Cherkassk d e p o s i t , t h e u n l i m i t e d compounds c o n t e n t was cut down t o t h e c u r r e n t s t a n d a r d s .

As a r e s u l t of p u r i f i c a t i o n , t h e bromine

number, b o t h o f reforming c a t a l y s t and b e n z o l

-

t o l u o l e x t r a c t , was c u t

down t o 0.05 g bromine/100 m l , from a bromine number p r i o r t o p u r i f i c a t i o n o f 1 . 5 and 0.8 co r r e s p o n d i n g ly .

The a c t i v i t y o f b o t h 'Banata'-made ad so r -

b e n t s u t i l i z e d abroad, and Rumanian p r o d u c t s , i s below 2 . 3 g/g (Ovcharenko

e t a l . , 1972). The n a t u r a l g a s desiccation/purification p r o c e s s removes b o t h m o i st u r e and o r g a n i c compounds, t h e c o n t e n t s o f which r each 300

-

500 mg/m3.

Mo i s t u r e and condensate f r e e gas d u r i n g t h e v er y f i r s t minutes o f p u r i f i c a t i o n

i s due t o t h e u s e o f s i n g l e - l a y e r a b s o r b e n t .

But w i t h t h e ab so r b en t r e a c h i n g

s a t u r a t i o n p o i n t , water s t a r t s t o expel condensate and i t s c o n t e n t i n t h e g as rises s h a r p l y .

241

Assuming a t w o - l a y e r composition, t h e problem can b e s o l v e d : t h e f i r s t l a y e r a b s o r b s mainly water, w h i l e t h e second a b s o r b s c o n d e n s a t e . abroad u t i l i z e mostly z e o l i t e d e s i c c a n t s .

Specialists

For t h e same p u r p o s e i n t h e USSR,

t h e f o u r t h l a y e r o f t h e Cherkassk d e p o s i t i s s u c c e s s f u l l y u t i l i z e d , u s i n g acid-activated montmorillonite f o r condensate absorption.

For b o t h removed

components, dew p o i n t i n t h e i n i t i a l p e r i o d was under minus 4OoC, w h i l e i n t h e f i n a l p e r i o d , w i t h i n 40

-

45 m i n u t e s , i t was minus 15 t o minus 2OoC.

Experimental arrangement i s : p r e s s u r e - 60 k 3 atm.; g a s speed - 1 . 2 m3/h p e r 100 g a d s o r b e n t . ( f o r condensate).

I n i t i a l dew p o i n t : + 15OC ( f o r w a t e r ) and + 10-12OC

I t i s w o r t h w h i l e n o t i n g t h a t t h e developed a d s o r b e n t

(Ovcharenko e t a l . , 1966) i n i t i a t e s d e s o r p t i o n a t 180 - 2OO0C, pressure.

c u t t i n g down

Afterwards, t h e adsorbent f u l l y r e s t o r e s i t s p r o p e r t i e s .

E x h a u s t i v e s t u d i e s of p h y s i c a l / c h e m i c a l and c o l l o i d / c h e m i c a l p r o p e r t i e s

of p a l y g o r s k i t e and i t s g e n e t i c a s s o c i a t i o n s w i t h m o n t m o r i l l o n i t e p r e p a r e d t h e way t o u s e them f o r t h e p r o d u c t i o n o f a d s o r b e n t s , c a t a l y s t s , i r o n o r e p e l l e t b i n d e r s , major components o f f l u s h i n g f l u i d s , p l u g g i n g s y s t e m a d d i t i v e s and o t h e r m a t e r i a l s i n d i f f e r e n t domains o f p r a c t i c e .

REFERENCES Fersman, A . , 1955. Magnesia S i l i c a t e s S t u d i e s . S e l e c t e d w r i t i n g s . USSR Acad. S c i . P u b l i s h e r s , 1:125-512. K r u g l i t s k y , N,N., Grankovsky, I . G . , Vagner, G . R . and Detkov, V . P . , 1974. P h y s i c a l and Chemical Mechanics o f t h e G r o u t i n g Mortar, Kiev, 'Naukova Dumka' P u b l i s h e r s , 320 pp. Kukovsky, Y . G . , 1960. P a l y s o r s k i t e c l a y s i n t h e U k r a i n e . S o v i e t Geology, 7 :117-1 19. Kukovsky, Y . G . and O s t r o v s k a y a , A . B . , 1961. F i r s t p a l y g o r s k i t e ( a t t a p u l g i t e ) d e p o s i t i n t h e USSR. P r o c e e d i n g s o f t h e All-Union M i n e r a l o g i c a l S o c i e t y , 90 :598-601. Lomova, O.S., 1979. P a l y g o r s k i t e s and S e p i o l i t e s as I n d i c a t o r s o f t h e G e o l o g i c a l S i t u a t i o n , M . , 'Nauka' P u b l i s h e r s , 180 p p . Ovcharenko, F.D., M a r t s i n , I . I . , O s t r o v s k a y a , A . B . and V a l i t s k a y a , V . M . 1966. Impact o f hydrothermal c o n d i t i o n s o f t r e a t m e n t on p h y s i c a l and chemical p r o p e r t i e s of c l a y m i n e r a l s , P r o c e e d i n g s o f t h e USSR Acad. S c i . 168:396-399 Ovcharenko, F . D . , Kukovsky, T.G., Nichiporenko, S . P . , Vdovenko, N . V . , T r e t i n n i k , V . Y . , K r u g l i t s k y , N . N . and P a n a s e v i t c h , A . A . , 1967. The C o l l o i d Chemistry o f P a l y g o r s k i t e . Daniel Davey & Co., New York, 101 pp. Ovcharenko, F . D . , M a r t s i n , 1.1. and L i t y a y e v a , Z . A . , 1972. Clay m i n e r a l s t u d i e s : Removal of u n l i m i t e d hydrocarbons from t h e a r o m a t i c c o n c e n t r a t e s . U k r a i n i a n Chemical J o u r n a l , 1 0 t h i n s t a l l m e n t , 32:1004-1009. Rateyev, M . A . , 1964. R e g u l a r i t y and Background o f t h e Clay M i n e r a l s i n Modern and A n c i e n t S e a B a s i n s . P r o c e e d i n g s of t h e USSR Acad. S c i . I n s t . Geology, 1 1 2 , 288 pp. Z a i n u l l i n , I.I., 1977. Assessment of t h e P a l y g o r s k i t e Clays i n t h e USSR. G e o l o g i c a l Survey o f Non-Metal D e p o s i t s , M. Viems, 31 p p . Z a k i r o v , M . Z . , 1974. P e t r o g r a p h i c a l t y p e s o f Uzbekistan r o c k s w i t h p a l y g o r s k i t e c o n t e n t . Uzbek SSR G e o l o g i c a l J o u r n a l , 4:21-25.

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243

OCCURRENCE OF PALYGORSKITE IN THE DECCAN TRAP FORMATION IN INDIA

M . K . HASNUDDIN SIDDIQUI Regional Research Laboratory Hyderabad, I n d i a . ABSTRACT One o f t h e w o r l d ' s l a r g e s t d e p o s i t s o f h i g h g r a d e a t t a p u l g i t e ( p a l y g o r s k i t e ) o c c u r s i n Hyderabad d i s t r i c t o f Andhra Pradesh, I n d i a .

The c l a y d e r i v e s i t s

o r i g i n from w e a t h e r i n g o f b a s i c i g n e o u s r o c k s o f t h e Deccan Trap f o r m a t i o n o f L a t e C r e t a c e o u s t o Eocene a g e .

The geology and g e n e s i s o f t h e d e p o s i t s have

been comprehensively d i s c u s s e d and d a t a on t h e i r mineralogy, based on c r y s t a l l o - c h e m i c a l c o m p o s i t i o n , d i f f e r e n t i a l t h e r m a l a n a l y s i s , x-ray d i f f r a c t i o n and e l e c t r o n microscopy are p r e s e n t e d .

The major i n d u s t r i a l uses made o f t h e

p a l y g o r s k i t e d e p o s i t s i n I n d i a and t h e newer f i n d i n g s on t h e i r p r e f e r r e d a p p l i c a t i o n are mentioned. INTRODUCTION E x t e n s i v e d e p o s i t s o f h i g h g r a d e a t t a p u l g i t e ( p a l y g o r s k i t e ) o c c u r i n Andhra Pradesh about 80 km west of Hyderabad i n t h e Vicarabad-Tandur area around t h e v i l l a g e s o f Timsanpalli-Gopalpur G i n g u r t h i (17'21':77'32'), 77'48'),

Godamguda (17'18l

(17°19':77048').

(17'21'

:77'38'),

Narsapur (17'22

M a r e p a l l i (17'21':77'32'), :77'52'),

Z a i d p a l l i (17'17'

:77'38'),

T a r i g o p a l a (17'19': :77'51')

and A l i p u r

The r e s e r v e s a t one s i n g l e s o u r c e i n t h e T i m s a n p a l l i -

M a r e p a l l i b e l t were e s t i m a t e d a t more t h a n 14 m i l l i o n t o n s .

Palygorskite

o c c u r s i n p o c k e t s a l o n g t h e margin o f t h e Deccan Trap f o r m a t i o n o f Late C r e t a c e o u s t o Eocene, as a decomposition p r o d u c t of t h e r o c k .

In t h e f o l l o w i n g ,

t h e geology and g e n e s i s of t h e c l a y a t t h e s e d e p o s i t s are b e i n g d i s c u s s e d and d e t a i l s o f t h e mineralogy and a p p l i c a t i o n s o f a n o t e d d e p o s i t a t T i m s a n p a l l i a r e given. GEOLOGY The Deccan T r a p s c o v e r an area o f about 200,000 s q u a r e miles i n Western and C e n t r a l I n d i a , p r o b a b l y c o n s t i t u t i n g t h e w o r l d ' s g r e a t e s t s p r e a d o f f i s s u r e e r u p t i o n s , w i t h t h e f l o w s o f l a v a p i l e d t o a h e i g h t o f 2,000 f t on t h e average.

The term "Trap" d e r i v e s i t s o r i g i n from Swedish "trappe" meaning

s t e p s , i n a l l u s i o n t o t h e s t e p - l i k e topography produced by s u c c e s s i o n s of h o r i z o n t a l lava flows.

The d e n u d a t i o n of t h e s e r o c k s r e s u l t e d i n b a r e

244

u n d u l a t i n g p l a i n s and p l a t e a u s o f t e n bound w i t h t e r r a c e s produced by t h e unequal w e a t h e r i n g o f a l t e r n a t i n g h a r d and s o f t l a y e r s .

The Deccan Traps a r e

very uniform i n m i n e r a l composition and are mostly b a s a l t s composed o f l a b r a d o r i t e f e l d s p a r and e n s t a t i t e - a u g i t e , ( p i g e g n i t e ) , which i s r i c h e r i n i r o n and magnesia and p o o r e r i n p o t a s h and lime t h a n normal a u g i t e . times o c c u r s .

O l i v i n e some-

T i t a n i f e r r o u s m a g n e t i t e i s an a c c e s s o r y , and i n f i n e - g r a i n e d

t y p e s t h e r e i s some r e s i d u a l g l a s s which a l t e r s t o p a l a g o n i t e (Mahadevan and Kazim, 1945).

The Trap rocks i n t h e a r e a are v e s i c u l a r t o massive i n n a t u r e

and dark g r e y t o weathered brown

i n colour.

Along t h e f r i n g e s o f t h e Deccan

Traps a r e s e e n i n t e r t r a p p e a n o u t c r o p s c o n s i s t i p g m o s t l y o f c h e r t y l i m e s t o n e s ,

marls, b r i g h t r e d e a r t h c a l l e d ' b o l e ' and p o o r l y compacted f e l d s p a t h i c sandstone.

The c h e r t y l i m e s t o n e s are found as p e b b l e s and b o u l d e r s strewn i n

the field.

On some o f t h e l i m e s t o n e areas i n t h e margin o f t h e Deccan T r a p s ,

there is a t h i n c r u s t of ferruginous clay ( t e r r a rossa), not unlike l a t e r i t e s i n appearance, produced by t h e removal o f s o l u b l e calcium and magnesium c a r b o n a t e s and t h e accumulation o f i n s o l u b l e alumina and i r o n r e s i d u e s .

The c l a y

o c c u r s beneath t h e weathered Traps and a t p l a c e s i n t e r b e d d e d w i t h c h e r t and calcareous material.

I t i s g r e y i s h w h i t e t o b u f f i n c o l o u r and when d r i e d

s t i c k s s t r o n g l y t o t h e tongue. t h e overburden from 3m t o 5m.

The bed t h i c k n e s s v a r i e s from 0.5m t o 3m and Mineralogy o f t h e c l a y r e v e a l e d t h a t i t i s a

high g r a d e p a l y g o r s k i t e ( S i d d i q u i , 1 9 6 7 ) .

There appear t o have been i n t e r v a l s

between t h e o u t p o u r i n g s o f s u c c e s s i v e l a v a s , a t t i m e s long enough f o r s h a l l o w lakes t o form on t h e i n e q u a l i t i e s o f t h e t r a p s u r f a c e .

These i n t e r t r a p p e a n

sediments d e p o s i t e d i n t h e s h a l l o w lakes s u g g e s t an a d d i t i o n a l ,

'intertrappean

l a c u s t r i n e ' occurrence o f p aly g o rs k it e i n India. METHODS

X-ray d i f f r a c t o g r a m s o f o r i e n t e d specimens was o b t a i n e d on a P h i l i p s PW 1050 d i f f r a c t o m e t e r u s i n g CuKa r a d i a t i o n and a scanning speed o f minute from 1.5'

0 t o 10'

and 1' 0 p e r minute from '5

E,

0 t o 25'

go

0 per

8.

The DTA r e c o r d was o b t a i n e d on a Leeds & Northrup DTA a p p a r a t u s , w i t h h e a t i n g r a t e o f 10°C/min.

The sample h o l d e r was o f t h e Roberts and Grimshaw

p a t t e r n embedded w i t h P t - P t l O % R h thermocouples.

Calcined alumina was used as

an i n e r t r e f e r e n c e material.

For e l e c t r o n micrography, t h e specimen was p r e p a r e d by p l a c i n g a d r o p l e t o f aqueous s u s p e n s i o n o f t h e c l a y on a t h i n formvar f i l m s u p p o r t e d on a 200mesh copper d i s c and by s u b s e q u e n t a i r d r y i n g .

I t was examined under a

P h i l i p s EM-200 e l e c t r o n microscope a t an a c c e l e r a t i n g v o l t a g e o f 100 kv.

,

245 RESULTS AND DXSCUSSION

Comprehensive s t u d i e s on t h e m i n e r a l c h a r a c t e r i z a t i o n o f a major c l a y d e p o s i t a t T i m s a n p a l l i have been c a r r i e d o u t .

The d a t a are p r e s e n t e d i n t h e

f o 1lowing : Chemical a n a l y s i s and c r y s t a l l o c h e m i c a l composition Chemical a n a l y s i s o f t h e c l a y i s g i v e n i n Table I .

The s e l e c t i v e d i s s o l u -

t i o n o f t h e c l a y i n h y d r o c h l o r i c a c i d p r o v i d e d d a t a f o r r e f i n i n g i t s chemical composition ( S i d i q u i , 1973).

The c r y s t a l l o - c h e m i c a l s t r u c t u r e o f T i m s a n p a l l i

TABLE I . Chemical composition and c a t i o n d i s t r i b u t i o n p e r u n i t c e l l of T i m s a n p a l l i p a l y g o r s k i t e on t h e b a s i s o f a c i d d i s s o l u t i o n d a t a . Per c e n t Composite clay SiO, A1203

Inter layer

53.70

1.23

Fe203

7.96

Palygorskite mono-mineral

Negligible

-

53.70 7.78 7.96

CaO

0.92 8.45

0.92

Na20

0.14

0.112

1.57

1.26

TetraS i 7.80 A 1 0.20 Octa-

1.23

MgO

L.I.

Insoluble minerals

7.78

TiQ

K2 0

Free oxides

Cations per unit cell

0.92

-

8.45

-

0,112

1.26

A1 1.130 Fe 0.870 Mg 1.830

I n t e r 1aye r Na 0 . 0 3 1 K 0.230 Ca 0 . 1 4 0

18.13

p a l y g o r s k i t e t h u s d e r i v e d was: IV

(si7. gA1O. 2)

(*'I.

3+ 13Fe0. 87Mgl,83)"

020Ca0, 14Na0. 03

The l a r g e s u b s t i t u t i o n of A 1 and F e f o r Mg i n t h e o c t a h e d r a l l a y e r i s t y p i c a l o f p a l y g o r s k i t e s r e p o r t e d so f a r .

246

Fig. 1.

a. b.

--------

X-ray diffractogram of o r i e n t e d specimen of Timsanpalli DTA record of Timsanpalli p a l y g o r s k i t e .

palygorgkite;

Fig. 2.

Electron micrograph of Timsanpalli palygorskite.

N P -4

248 X-ray examination The X-ray d i f f r a c t o g r a m ( F i g . 1-a) shows one i n t e n s e r e f l e c t i o n a t 10.37

8,

and one o f medium i n t e n s i t y a t 6 . 4 4 of palygorskite.

8

c o r r e sp o n d i n g t o 110 and 200 r e f l e c t i o n s

These are followed by o t h e r c h a r a c t e r i s t i c r e f l e c t i o n s o f t h e

same m i n er al a t d = 5.36

8

(130), 4.45

8

(040), 3 .2 3

8

(400) and 2.56

8

(440).

The a n a l y s i s does n o t r e v e a l t h e p r e s e n c e o f any i m p u r i t i e s i n t h e sample

except minute q u a n t i t i e s o r q u a r t z , as i n d i c a t e d by t h e s l i g h t i n t e n s i t y r e f l e c t i o n s a t 4.25

1 and

3.34

8.

D i f f e r e n t i a l t h er m a l a n a l y s i s The DTA r eco r d o f t h e c l a y ( F i g . 1-b) shows an i n t e n s e endothermic r e a c t i o n due t o i n i t i a l d e h y d r a t io n w i t h a maximum a t 105OC, followed by a n o t h e r o f moderate i n t e n s i t y w it h i t s peak around 28$OC which i s a t t r i b u t e d t o t h e l o s s of w a t e r co - o r d i n a t e d w i t h magnesium. e x h i b i t s its maximum a t about 450OC.

The main d eh y d r o x y l at i o n r e a c t i o n The f i n a l endothermic-exothermic peaks

appear a t 8OO0C and 830°C, r e s p e c t i v e l y .

The DTA r eco r d i s c h a r a c t e r i s t i c f o r

a palygorskite clay. E l e c t r o n micrograph The micrograph ( F i g . 2) shows f i b r e s o f p a l y g o r s k i t e i n t h e i r n a t u r a l o r i e n t a t i o n t o e x i s t i n t h e form o f s h e a t h s . about 40

8 wide.

The f i b r e s are ex t r em el y f i n e ,

They are commonly lo n g e r th an 2 microns b u t are f r e q u e n t l y

broken i n t o smaller s i z e s . S i n c e l i t t l e i s known about t h e means by which p a l y g o r s k i t e m i n er al s may be s y n t h e s i z e d , it i s r a t h e r d i f f i c u l t t o s u g g e s t any mechanism f o r t h e formation

of t h e s e c l a y s i n n a t u r e .

I t i s , however, a g e n e r a l o b s e r v a t i o n t h a t t h e

commonest o ccu r r e n c e o f t h e s e m i n e r a l s i s i n a s s o c i a t i o n w i t h c a l c a r e o u s sediments i n a s i t u a t i o n where smectite c o u ld be ex p ect ed .

Heystek and Schmidt

(1954) s u g g es t ed t h a t i n t h e T r a n s v a a l d e p o s i t (South A f r i c a ) , p a l y g o r s k i t e has been d e r i v e d from m o n tm o r il lo n i te .

Stephen (1954) d e s c r i b e d t h e o ccu r r en ce o f

p a l y g o r s k i t e from t h e S h e t l a n d Isles (England) o c c u r r i n g i n a s s o c i a t i o n w i t h mo n t m o r i l l o n i t i zed s y e n i t e ; f u r t h e r , he s u g g e s t s t h a t t h e a l t e r a t i o n o f t h e s y e n i t e rock is due t o t h e a c t i o n o f hydrothermal s o l u t i o n .

A l a r g e l y hydro-

thermal mode o f o r i g i n h a s a l s o been s u g g e s t e d by C a i l l e r e (1951) f o r p a l y g o r s k i t e o c c u r r i n g i n g r a n i t e a t T a f r a o u t , Morocco.

Many o f t h e o ccu r r en ces o f

t h i s m i n e r a l , however, are under c o n d i t i o n s which p r e c l u d e a hydrothermal mode o f f o r m at i o n .

I n sediments o f l a c u s t r i n e o r i g i n where s a l t s and car b o n at es are

l i k e l y t o occumulate, t h e dominant c l a y m in e r al components are i l l i t e , s m e c t i t e , s e p i o l i t e and p a l y g o r s k i t e .

The l a t t e r type o f c l a y m i n er al was shown by t h e

i n v e s t i g a t i o n s o f M i l l o t (1949) and G r i m (1953) t o b e p a r t i c u l a r l y p r e v a l e n t i n

249 s e d i m e n t s t h a t have accumulated i n d r y d e s e r t l a k e s .

I n A u s t r a l i a , it had

formed from t h e w e a t h e r i n g o f b a s a l t i c r o c k s (Rogers e t a l . , 1 9 5 4 ) .

This

s u g g e s t s t h a t p a l y g o r s k i t e f o r m a t i o n i n I n d i a may a l s o have o c c u r r e d by t h e w e a t h e r i n g o f t h e Ueccan Trap r o c k s which a r e m o s t l y composed o f b a s a l t s . Under c o n d i t i o n s o f a l t e r n a t i n g wet and d r y s e a s o n s , t h e v e s i c u l a r Trap r o c k s o f b a s a l t i c n a t u r e undergo an underground decomposition r e s u l t i n g i n t h e removal o f a l k a l i and a l k a l i n e e a r t h m e t a l s and s i l i c o n and r e t e n t i o n o f aluminium, magnesium and c a l c i u m , which p r o b a b l y recombine t o form p a l y g o r s k i t e . APPLICATION The p a l y g o r s k i t e c l a y s f i n d wide a p p l i c a t i o n s i n i n d u s t r y i n I n d i a e s p e c i a l l y

as a d s o r b e n t s and c l a r i f y i n g a g e n t s f o r d e c o l o r i z i n g and r e f i n i n g o f v e g e t a b l e and m i n e r a l o i l s and . f o r r e c l a m a t i o n o f used l u b r i c a t i n g o i l s .

Suitably

p r o c e s s e d c l a y s were p r o v e d t o b e u s e f u l a s c a t a l y s t s , c a t a l y s t c a r r i e r s and c a t i o n exchangers ( S i d d i q u i , 1968; CSIR News, 1971).

The u s e f u l n e s s o f t h e

d e p o s i t s i n t h e p r e p a r a t i o n of d r i l l i n g muds, a s p e s t i c i d e c a r r i e r s and molec u l a r s i e v e s h a s a l s o been comprehensively s t u d i e d ( S i d d i q u i , 1981).

The

newer and p r o b a b l y v e r y i m p o r t a n t a p p l i c a t i o n o f p a l y g o r s k i t e c l a y hence e x p l o r e d i s i n t h e p r e s e r v a t i o n o f food g r a i n s .

The s t u d i e s s o f a r have l e d t o

d e f i n i t e f i n d i n g s as t o t h e s a f e a p p l i c a t i o n of p a l y g o r s k i t e d u s t i n t h e p r e s e r v a t i o n o f s e e d s (Varma and S i d d i q u i , 1977; S i d d i q u i , 1979) s o t h a t t h e chemical p e s t i c i d e s commonly b e i n g used f o r t h i s p u r p o s e c o u l d p o s s i b l y b e dispensed with. REFERENCES

C a i l l e r e , S . , 1951. S u r l a p r e s e n c e d ' u n e p a l y g o r s k i t e a T a f r a o u t (Maroc.). Compt. Rend Acad. S c i . , F r . , 233:697-698. CSIR, New D e l h i , 1971. Development o f B l e a c h i n g E a r t h s - Work o f R R L , Hyderabad. CSIR N e w s , 2 1 : l l - 1 2 . G r i m , R . E . , 1953. Clay Mineralogy, McGraw H i l l , N e w York, 354 p p . Heystek, H . and Schmidt, E . R . , 1954. The m i n e r a l o g y of attapulgite-montmorillon i t e d e p o s i t s i n t h e Springbok F l a t s , T r a n s v a a l . T r a n s . Geol. SOC. S . A f r . , 56:99. Mahadevan, C . and Kazim, S . , 1945. Types of topography b a s e d on e r o s i o n of r o c k s . J . Hyderabad Geol. S u r v . 4 , p a r t 2 . M i l l o t , G . , 1949. R e l a t i o n s e n t r e l a c o n s t i t u t i o n e t a1 g e n e s e d e s r o c h e s s e d i m e n t a i r e s a r g i l e u s e s . Geol. Appl. P r o s p e c . Min., 2:l-352. Rogers, L . E . , M a r t i n , A . E . and N o r r i s h , K . , 1954. The o c c u r r e n c e o f p a l y g o r s k i t e n e a r I p s w i c h , Queensland. Miner. Mag., 30:534:540. Siddiqui, M.K.H., 1967. P a l y g o r s k i t e c l a y s from Andhra P r a d e s h , I n d i a . Clay Min., 7:120-123. Siddiqui, M.K.H., 1968. B l e a c h i n g E a r t h s , Pergamon Press, Oxford, 63 pp. 1973. D e t e r m i n a t i o n of c r y s t a l l o - c h e m i c a l f o r m u l a e of some Siddiqui, M.K.H., I n d i a n b e n t o n i t e s and a t t a p u l g i t e c l a y s by s e l e c t i v e d i s s o l u t i o n . Report of t h e work, I n s t i t u t e o f I n o r g a n i c Chemistry, Slovak Academy o f S c i e n c e s , B r a t i s l a v a , Czechoslovakia.

250

Siddiqui, M.K.H., 1979. P r e s e r v a t i o n o f f o o d g r a i n s u s i n g a t t a p u l g i t e c l a y . Report s u b m i t t e d t o Govt. of I n d i a , Dept. o f S c i e n c e and Technology. S i d d i q u i , M . K . H . , 1981. Clay m o l e c u l a r s i e v e s t r u c t u r e s . Symposium on Molecular S i e v e s and T h e i r A p p l i c a t i o n s . I n d i a n I n s t i t u t e o f Chemical E n g i n e e r s , New D e l h i , Nov. 13-14, A b s t r . p . 13 ( P r o c . under p u b l i c a t i o n ) . Stephen, I . , 1954. An o c c u r r e n c e o f p a l y g o r s k i t e i n t h e S h e t l a n d I s l e s . Miner. Mag., 30:471-478. Varma. B . K . and S i d d i q u i , M . K . H . , 1977. C o n t r o l of s t o r a g e p e s t s t h r o u g h i n e r t d u s t s . I n d i a n Farming, 2 7 ( 5 ) , 2 1 ( P a p e r reviewed i n Chemical Weekly, 2 3 ( 4 ) , 56 (1977).

251

SEPIOLITE CLAY DEPOSITS IN SOUTH CHINA*

ZHANG RENJUN Yichang I n s t i t u t e o f Geology and Mineral Resources, Chinese Academy o f G e o lo g i c a l S c i e n c e s A s now known from comparisons w i t h common c l a y s o r c l a y m i n er al s such a s k a o l i n i t e , s m e c t i t e and i l l i t e , s e p i o l i t e as well a s p a l y g o r s k i t e ( o r a t t a p u l g i t e ) are r a t h e r r a r e i n n a t u r e . mentioned a s f o l lo w s :

A few o c c ur r en ces i n so u t h China can be

(1) P a l y g o r s k i t e c l a y d e p o s i t s i n Miocene b a s a l t i c p y r o c l a s t i c sediments (Liuhe. J i a n g s u P r o v i n c e ) , (2) P a l y g o r s k i t i c mountain l e a t h e r a s s o c i a t e d w i t h i c e l a n d s p a r and common c a l c i t e i n c a v i t i e s o f Permian d o l o m i t i c l im est o n e (Qongxian, Sichuan P r o v i n ce) . ( 3 ) F i b r o u s s e p i o l i t e a s s o c i a t e d w i t h a g a t e , c a l c i t e e t c . i n v e s i c l e s of

o l i v i n e b a s a l t (Duan, Guangxi Zhuang Autonomous Region). (4) Marine s e p i o l i t e c l a y d e p o s i t s o f e a r l y Permian age (Jingdezhen, F u l i a n g and Leping, J i a n g x i P r o v i n c e ) . I n t h e s u b u r b s and s u r r o u n d i n g d i s t r i c t s o f Ji n g d ezh en , famous a l l over t h e world f o r h e r d e l i c a t e p o r c e l a i n s and e x c e l l e n t p o r c e l a i n t ech n i q u e, a c l a y , s o - c a l l e d Leping w h i t e e a r t h , was found s e v e r a l hundred y e a r s ago and has long been used as a f i r e c l a y f o r making s a g g e r s (Xia-bo i n Chinese) o r p r o t e c t i v e boxes i n which d e l i c a t e ceramic p i e c e s are p l aced w h i l e b e i n g baked.

The

i n v e n t i o n o f s a g g e r i n a n c i e n t China p l a y s an i m p o r t an t r o l e i n t h e development of Chinese p o r c e l a i n i n d u s t r y . I n 1947, based on f i e l d o b s e r v a t i o n s and a few d a t a on chemical a n a l y s i s , t h e Leping wh i t e e a r t h was f i r s t r e c o g n iz e d as a s e p i o l i t e c l a y o f marine o r i g i n o f e a r l y Permian a g e . and EM.

Later (1960’s) t h i s was confirmed by DTA, XRD

I t i s now c e r t a i n t h a t Leping w h it e e a r t h i s a high-magnesium,

aluminium hydrous s i l i c a t e w i t h c h a i n s t r u c t u r e . s i l i c a t h an t h e t h e o r e t i c v a l u e would i n d i c a t e .

t a l c i s a l s o an i m p o r ta n t m in e r a l c o n s t i t u e n t .

low-

I t c o n t a i n s however more In addition t o s e p i o l i t e , Whether t h e t a l c i s a s y n g e n e t i c

mi n er al o r a m i n e r a l transformed from s e p i o l i t e i s s t i l l a problem t o b e settled.

* P r es en t ed a t t h e I n t e r n a t i o n a l Clay Conference 1981.

252

I n t h e Jingdezhen-Leping a r e a , t h e lower Permian s e r i e s i s a sequence o f marine n o n - c l a s t i c sedimentary rocks, 500-600 meters t h i c k , c o n s i s t i n g mainly of d a r k grey limestone, swinestone, dolomitic limestone, c h e r t y limestone with massive c h e r t y beds a t t h e t o p .

The s e p i o l i t e c l a y occurs a s

l e n t i c l e s o r t h i n beds i n t h e c h e r t y limestone, o r sometimes i n t e r c a l a t e d with t h e l a t t e r , and o c c a s i o n a l l y contains some c h e r t o r limestone nodules. phosphate has been i d e n t i f i e d i n any horizon.

No

This s e r i e s extends over

400 km, along t h e Leping-Pingqiang subsided b a s i n , southwestward a s f a r a s t h e Liling-Pingqiang a r e a where t h e same c l a y bed crops out a g a i n . L i l i n g i n Hunan Province, i s a new p o r c e l a i n c i t y i n south China. suburbs and a d j a c e n t l o c a l i t i e s , ("Xiani",

In i t s

t h e r e a r e many occurrences of L i l i n g Xiani

Chinese f o r sagger e a r t h ) .

Not only i n i t s appearance, but a l s o i n

many o t h e r a s p e c t s such as s t r a t i g r a p h i c horizon, occurrence, chemical comp o s i t i o n and usage, it i s much a l i k e t o Leping s e p i o l i t e c l a y , while c o n t a i n i n g much more t a l c .

Thus, t h e i n t e r p r e t a t i o n f o r t h e formation of t a l c may be

considered a key p o i n t f o r t h e s e t t l e m e n t of t h e problem of c l a y g e n e s i s i n t h i s area. Since both s e p i o l i t e and p a l y g o r s k i t e a r e h i g h l y s e n s i t i v e t o e a r t h s u r f a c e c o n d i t i o n s , t h e i n c r e a s e of geotherm with depth, o r of load caused by t h e weight o f o v e r l y i n g rocks, i s l i a b l e t o g i v e r i s e t o s t r u c t u r a l t r a n s f o r mations, p a r t i c u l a r l y i n sedimentary d e p o s i t s o l d e r than Mesozoic.

Commonly,

t h e new minerals w i l l be t a l c , s a p o n i t e , s t e v e n s i t e o r o t h e r magnesium-bearing montmorillonites.

This may be a reason why pre-Mesozoic s e p i o l i t e and

p a l y g o r s k i t e c l a y d e p o s i t s a r e so r a r e . In t h e a r e a s mentioned above, t h e s e p i o l i t e c l a y d e p o s i t s a r e widely d i s t r i b u t e d and have got considerable r e s e r v e s .

For p r a c t i c a l purposes,

much research work on c l a y technology w i l l have t o be c a r r i e d o u t .

253

SEPIOLITE: PROPERTLES AND USES ALVAREZ, A . Research and Development Manager, TOLSA S A , Madrid, Spain ABSTRACT The structure and properties of sepiolite are reviewed.

Surface proper-

ties, such as porosity and sorption are detailed, as well as dehydration and thermal behaviour.

Industrial applications of sepiolite are based on: a) Sor-

btive properties; b) rheological properties; c) catalytic properties; The rheological behaviour of sepiolite suspensions, as expressed by viscosity, is shown to be related to following factors: type of medium (aqueous or organic), type and concentration of electrolyte, pH, shear-stress and pregelification. With appropriate pretreatments, sepiolite is shown to be useful in following applications: Absorbents, environmental deodorants, catalyst carriers, polyesters, asphalt coatings; paints, pharmaceutical uses, decolorizing agents, filter aids, anticaking agents, phytosanitary carriers, cigarette filters, plastisols, rubber, animal nutrition, detergents, cosmetics, agriculture (soil conditioning, fluid carriers for pregerminated seeds, seed coating; fertilizer suspensioqs) grease thickeners. YCR paper, drilling fluids. INTRODUCTION Sepiolite belongs to the clay family known as sepiolite-palygorskite. In 1913, Fersman applied the term palygorskite, to a family of fibrous hydrous

magnesium silicates forming an isomorphous series between two extreme members: an aluminium extreme called paramontmorillonite, due to its almost complete similarity to montmorillonite, differing only in its fibrous structure and a magnesium extreme called sepiolite. Sepiolite is known since a Ion? time. A s early as 1758, Cronsted described Keffekil Tartarorum, a mineral which may very well have been sepiolite. Later in 1 7 9 4 Kirwan referred to sepiolite as Myrsen and Meerschaum and, in 1801, Hauy called it Ecume de Mer.

A s far as we know Glocker was the first

to use the term sepiolite, deriving the new name from the Greek q s i a which means cuttlefish because of the resemblance of its light and porous internal shell or "bone" to sepiolite. Sepiolite has been used for hundreds of years in the manufacturing of pipes as for instance the pipes of Lemgo (I.ippe, Germany) manufactured from 1750 to 1 9 1 2 (Martin-Vivaldi,, Robertson, 1 9 7 1 ) .

The sepiolite of Vallecas,

254

along with clay from Capodimonte (Prado, 1864) was used in the ceramic paste required to make the famous porcelain manufactured in "La China" founded in 1760 by Carlos I11 of Spain until its destruction by Napoleon's troops in 18".

During this epoch, the french chemist, Joseph Louis Proust reported that the Waiorcan ceramist Bartolime Sureda, had successfully casted small fragments of Sevres porcelain which had previously been considered infusible in a crucible of quartz feldspar and sepiolite (Robertson, 1957). Sepiolite is presently used in a wide variety of fields which take advantage of the great absorption capbcity, rheological behaviour as well as catalytic action of the clay: all of these properties may be improved by various treatments.

The applications are based on following three types of

properties:1.

-

Sorptive Properties

2.

-

Rheological Properties

3.

Catalytic Properties

The sorption capacity of sepiolite renders it valuable as a bleaching and clarifying agent, filter aid, industrial absorbent and carrier of catalysts and pesticides.

The rheological properties of sepiolite render it valuable

as a thickening, suspending or thixotropic agent and its diverse applications include a seemingly limitless range of uses from the manufacture of cosmetics to that of paints and even fertilizers. Recently new uses of sepiolite as catalyst have been reported. Sepiolite is often found associated with other clays and non-clay minerals such as carbonates, quartz, feldspar and phosphates (Martin- Vivaldi and Cano-Ruiz, 1953).

The most important occurrences of sepiolite are found

in Vallecas, Spain; Ampandrandava, Madagascar; Eskichehir, Turkey; Nevada, USA; Amboseli, Tanzania; Korea and France.

The deposits available to industry,

however, are few. STRUCTURE Sepiolite may appear in two forms (Fersman, 1 9 1 3 ) :

ci

sepiolite, or para-

sepiolite, which occurs as large bundles of crystaline fibers, and B sepiolite which occurs as amorphous aggregates or small flat rounded particles.

Sepio-

lite may adopt a compact or a soft porous macroscopic aspect or, less frequently, a structure of fibrous masses, like the sepiolite found in Ampandrandava, Madagascar.

It may also be found in lumps as in Eskichehir, Turkey, in sedi-

mentary beds as in Amboseli, Tanzania or in matted plates, commonly called "mountain leather", with either an eaithy or a waxy lustre. Vallecas sepiolite appears in compact form.

The felting in one, two or three dimensions of

255

the extremely thin single crystal fibers of sepiolite leads to their aggregation into these various forms (Preisinger, 1 9 6 3 ) . Sepiolite has fibers of 0 . 2 to 2 a thickness of 50 to 100

8

in length, 100 to 300

8

in width and

(Martin Vivaldi and Robertson, 1971), with the

exception of the Ampandrandava sepiolite whose fibers may reach several milimeters or even centimeters in length. The colour of sepiolite when it occurs in compact lumps is white or creamcoloured with gFey, green, rose or even crimson tones, depending on the degree of contamination. The fibrous forms, like that of Ampandrandava, are white or light yellow. The specific gravity of sepiolite is 2 to 2.3 gr/cm3. The porous types are able to float in water which is why it has received the name of "sea foam". Mohs hardness is 2 to 2 . 5 , the mean refractive index is 1 . 5 0 and it has a value of 2E:IlZ" with a negative biaxial optical sign. After the first attempt to define the structure of sepiolite by Longchambon ( 1 9 3 7 ) ,

Nagy and Bradley ( 1 9 5 5 ) presented the first structural model which

consisted of two pyroxene chains linked to form an amphibole chain with an extra tetrahedron of silica added at regular intervals on each side, Shortly thereafter, Brauner and Preisinger ( 1 9 5 6 ) presented a model with three pyroxene chains linked to form two amphibole chains.

These two models do not differ in

the crystal size but they differ in the number of octahedral cations which are

8 in Brauner and Preisinger's model and 9 in Nagy and Bradley's. Furthermore, the number of hydroxyls in the Braunder and Preisinger's model is four instead of six and the number of molecules of zeolitic water is six instead of eight. The fibrous structure of sepiolite is, therefore, composed of talc-like ribbons with two sheets of tetrahedral silica units, linked by means of oxygen atoms to a central octahedral sheet of magnesium so that the tetrahedral sheet of silicon is continuous, but with the directions of the apical extreme of the tetrahedral sheet of silica inverted after every six tetrahedral units.

This

determines the presence of channels oriented in the longitudinal direction of the fibers.

The section of these channels, where water and other fluids can

penetrate, is 3.6 x 10.6

8

(Fig. 1 ) .

Three types of water molecules can be identified in sepiolite:

-

Absorbed water bonded by hydrogen bonds at the external surface or into the channels, in which case it is called zeolitic water.

-

Crystal water which completes the coordination of the octahedral cations at the edges of the talc-like ribbons.

-

Constitution water or hydroxyl groups.

256

b

Fig. 1 , top: Structure of sepiolite according to Brauner and Preisinger bottom:

Structure of sepiolite anhydride

257

Martin Vivaldi and Cano-Ruiz (1956) suggested that the palygorskitesepiolite minerals occupy a region of continuity between the dioctahedral and trioctahedral minerals

so

that there is a continuous series with two planar

structural extremes, and where the intermediate members have a fibrous structure.

The change in structure from lamellar to fibrous i s produced when the

number of vacancies is increased.

When the number of vacant octahedral po-

sitions is one for every nine, the structure is that of sepiolite, by increasing the number of vacancies to one for every five, we reach the structure of palygorksite, and if one cantinues to increase the number of vacancies, a lamellar mineral structure'results in which the octahedral holes can be distributed

Symmetrically.

The ideal structural formula of sepiolite according to the Nagy-Bradley model is the following: (Si12) (Mg9) 030 (OH)6

(OH2)4 6H20

And the formula according to the Brauner and Preisinger model is: (Si12) (Mg8) 030 ( O H ) 4

8H20

Most of the structural formulae that have been calculated for sepiolite indicate a small substitution of Si4+ by *I3+ or Fe3+ in the tetrahedral sheet. Furthermore, the majority of the analyses indicate that magnesium occupies 90 to 100% of the octahedral positions and that there are sufficient cations for filling of approximately 8 of these positions which would occupy all of the sites that appear on the Brauner-Preisinger model and which would leave one vacant site of the 9 positions supposed by the Nagy-Bradley model (Weaver and Pollard. 1973). Although magnesium sepiolite is the most common, other varieties have been identified. An aluminous sepiolite described by Rogers et al. (1956) has 19% of the octahedral positions filled with A13+ (Weaver and Pollard, 1973). In ferriferous sepiolite or xylotile,Fe3' of charge

can replace part of Si

4+, the deficit ?+

created being compensated by substitution of part of the Mg 3+ in the tetrahedral sheet by Fe (Caillere et al., 1948). Nickeliferous sepioso

lite or falcondoite containing 9.78% Ni02 in the octahedral sheet and sodium sepiolite or loughlinite have also been described (Caillere et al. 1982). With regard to cation exchange capacity (CEC), the data offered in the literature vary greatly.

For example, 3 to 15 meq/100 gr., (Grim, 1968), 20 -

to 45 meq/100 gr. (Weaver and Pollard, 1973), 20 to 30 meq/100 gr. (Caillere et al., 1982), 31,6 meq/100 gr. (Otsuka et al., 1973), 26 meq/100 gr. (Galan, 1979).

These differences may be due to the different crystalline compositions

of the sepiolites. The cation exchange capacity is due to the deficiency of 4+ charge caused by Si substitution with tri-valent ions that are internally

258

compensated to a great degree, and to the existence of broken bonds at the edges of the fiber which give rise to unsatisfied charges which could be balanced by adsorbed cations.

Broken bonds are possibly an important cause for

the exchange capacity of sepiolite especially in the more crystalline sepiolites (Grim, 1 9 6 8 ) . SURFACE AREA The surface area of sepiolite computed from the structural models described above, if we assumed a section.of 3.6 x 10.6

2

for the channels, is approxi-

mately 800-900 mz/gr., with 500 m2/gr. for the internal surface and 400 mz/gr. for the external surface.

(Serna and Van Scoyoc, 1 9 7 8 ) .

The surface area

available to different sorbates depends on the molecular capacity to penetrate the intra-crystalline channels.

According to Mffller and Kolterman ( 1 9 6 5 ) the

penetration capacity of the sorbates depends primarily on the size of the molecules, whereas Barrer et al. ( 1 9 5 4 ) ; Nederbragt ( 1 9 4 9 ) Martin Vivaldi et al. ( 1 9 5 8 ) , hold that only the polar molecules can penetrate into the channels. The direct relation of the available surface area to the nature of the sorbate results in the fact that the calculated surface are will vary with the used method.

For example, the surface area calculated using hexane is 330 m2/gr.

(Robertson, 1 9 5 7 ) , 6 0 m2/gr. using cetylpyridinium bromide (Greenland and Quirk, 1 9 6 4 1 , 275 m2 /gr. using pyridine (Ruiz-Hitzky et al. 1 9 8 3 ) and 276 mz /gr. when the BET method is used (Ruiz-Hitzky and Fripiat, 1 9 7 6 ) .

The fact that the

nitrogen sorption reaches a rapid equilibrium, (Barrer and Mackenzie, 1 9 5 4 ) , suggests that the nitrogen molecules do not significantly penetrate the intracrystalline channels and that the adsorption occurs on the external surfaces. The use of polar molecules allows to calculate the external and internal surface areas. Fen011 and Martin Vivaldi ( 1 9 6 8 1 , using ethylene glycol, obtained a total value of 470 mZ/gr. with an external surface area of 214 m2/gr. The studies made regarding the evolution of the nitrogen surface, using the BET method as a function of outgassing temperature (Barrer et al., 1 9 5 4 ; Dandy and Nadiye-Tabbiruka, 1 9 7 5 ; Fernandez-Alvarez, 1 9 7 0 , 1 9 7 8 ) , illustrate that the surface area increases as the temperature is increased and as the adsorbed and zeolitic water are removed, increasing the number of free positions accessible to the nitrogen molecules, up to a maximum of 250 to 360 m2/gr. At temperatures above 3OO0C, a sharp decrease in the accessible surface area occurs, owing to folding of the crystal (Preisinger, 1 9 5 9 ) .

The surface area

and the temperature at which the transition occurs depend on the size distribution of the particles and on the crystalline imperfections. Thus, the surface area of Ampandrandava sepiolite is 72 m2/gr., considerably less than the normal values found in microcrystalline sepiolite.

259

POROSITY Analysis of the data on nitrogen sorption, using the MP method (Mikhails, et al., 1968) allows the determination of the surface area of micropores whose width

is less than 16 to 20

8.

The Pierce method (1953), gives

area of pores whose radius is more than 15

2

us

the surface

("meso" and macro-pores).

Appli-

cation of both these methods to the surface area of the Vallecas sepiolite, shows that before folding occurs, micropores compose 60 to 70% of the surface area which disappear when the crystalline folding occurs at temperatures above 3OOOC. causing.a sharp decrease of the surface area.

I f we suppose that the

intra-crystalline channels are not accessible to the nitrogen molecules (Barrer and Mackenzie, 1954; Serna and Van Scoyoc, 1978) it appears that the crystalline folding profoundly reduces the roughness of the external surface. The surface area of sepiolite as well as its porosity can be modified by acid or thermal treatments (Dandy and Nadiye-Tabbiruka, 1975; Rodriguez-Reinoso et al., 1981; Jimenez-Lopez et al., 1978; Fernandez-Alvarez, 1970, 1972, 1978). As noted before, heating the sepiolite at temperatures of 100 to 150°C will increase the specific BET surface, removing the adsorbed or zeolitic water; heating at temperatures above 300°C will cause a sharp decrease of the surface area as well as the reduction of the number of pores whose diameter is less than 10

(Fernandez-Alvarez, 1970).

The surface area of sepiolite decreases

above 500°C which is attributed to sintering as well as

a more close packing

of the fibers, reducing the volume and mean radius of pores. The surface area

of sepiolite can be increased by acid treatment with HC1 in concentration of 5 % (Fernandez-Alvarez, 1972) which is attributed to changes in the surface

texture of sepiolite decreasing the number of pores with a radius below 10 and increasing the percentage o f pores with a radius between 10 and 50

8.

8

The

acid treatment increasesthe cross section of the intracrystalline channels making the entrance of sorbate molecules more easy.

At the same time the acid

treatment increases the thermal stability of sepiolite. Treatment with HN03 in concentration of 1N or less (Jimenez-Lopez et al., 1978) and heating to 2OO"C,

increases the number of pores, without appreciably

altering size distribution. Heating at higher temperatures will cause the pores to collapse and the higher the temperature of the thermal treatment, the more intense will be the collapse. DEHYDRATION AND H I G H TEMPERATURE PHASES The differential thermal analysis (DTA) curve shows a first large endothermic peak at 150°C with a slight peak at about 200'C.

At approximately 300

or 350°C a small endothermic peak appears, followed by a wider one at 450°C. At 750°C or 800°C a rather sharp peak occurs, followed by an exothermic peak

260

1L

.-

12

--

DTA

-

1W

Fig. 2.

200

300

LOO

YM

600

700

8bO

900

1000

TG

'c

Differential thermal and thermogravimetric analysis of sepiolite of Vallecas (Spain)

261 (Caillere and Henin, 1957)(Fig. 2 ) . The thermogravimetric analysis curve (TG) shows that the first weight loss, of 11% occurs at 200°C; between 200 and 350°C a weight l o s s of 2.8% can be observed and between 350 and 600°C the weight loss is of 3.0%.

At tempera-

tures above 6OO0C, the weight l o s s is 2.4% (Martin-Vivaldi and Fenoll P., 1970; Caillere and Henin, 1957). ENDOTHERMIC PEAK

<

200°C

to

400

to 750 to

350°C 600°C 800°C

800 to

850°C

250

WEIGHT LOSS ( % )

1 1 .o 2.8 3 .O 2.4

---

The 11% weight l o s s observed at 200"C, is attributed to the loss of water physically bonded to the sepiolite, adsorbed on the external surface and in the structural channels, that is the hygroscopic and zeolitic water, and therefore, the first weight loss will depend on the relative humidity. At approximately 3OO0C, another endothermic peak is reached and a weight l o s s of 2.8% attributed to the l o s s of two of the four crystallization water

molecules which are more weakly bonded, occurs (Serna, et al., 1975). observed at 300°C is an important structural change.

Also

The sepiolite is folded

by rotation of the structural blocks on the axis which passes through the Si-0-Si edge bonds which join the fiber units.

These approach the structural

bonds, allowing the magnesium ions to complete their coordination with the oxygen molecules of the neighbouring surface, giving rise to what is known as sepiolite anhydride (Preisinger, 1959, 1961; Martin Vivaldi, et al., 1958). The third peak, observed at 400 to 600°C and showing a 3.0% weight loss, is due to the elimination of the two other, more strongly bonded crystallization water molecules.

This water loss doesn't produce any apparent structural

changes. While the sepiolite anhydride produced at 300°C can be re-hydrated, recovering its original structure, the sepiolite anhydride obtained at 500°C is irreversible even under hydrothermal conditions (Fernandez-Alvarez, 1970; Nagata, et al., 1974). At 700°C a transient amorphous phase is formed, (Caillere, 1936), and at 800°C a sharp endothermic peak appears with a weight loss of 2.4% attributed to the loss of constitution water or hydroxyl groups.

Immediately afterwards

an exothermic peak occurs, attributed tothe development of a magnesium silicate phase.

This phase possibly represents the crystallization of enstatite, which

develops slowly to a maximum at about 1,350"C (Grim, 1968).

Above this tempe-

rature B-cristobalite is formed, this phase lasting until at least 1,500"C.

262

The material finally smelts at 1,550"C. SORPTION ACTIVE CENTERS Three types of active centers of absorption can be distinguished on the sepiolite surface (Serratosa, 1978).

1.

Oxygen atoms in the tetrahedral sheet of silica. Owing to the low isomorphous substitution grade present in the tetrahedral sheet of these minerals, the qxygen atoms are weak donors in electrons and their interaction with the sorbedspecies will therefore be weak.

2.

Water molecules coordinated with magnesium ions at the edges, which can form hydrogen bonds with the sorbed-species.

3.

Si-OH groups, originating from the breakage of Si-0-Si bonds o n the external surface of the tetrahedral sheet, which compensate the residual charge, by accepting a molecule.

or a hydroxyl

These groups are situated at intervals of 5

2

all along

the axis of the fiber and their abundance depends o n the dimensions of the fibers and the imperfections of the crystal.

These SiOH groups

can interact with adsorbed molecules on the external surface of the sepiolite and they are capable of forming covalent bonds with certain organic reagents. PROPERTIES The characteristic structure of sepiolite provides it with three types of basic properties that make it very useful in a wide range of applications. A s noted above, sepiolite possesses a great surface area with zeolitic

channels throughout the structure and pores where a large quantity of water or polar substances, including those of low polarity, can be adsorbed. The great sorptive capacity of sepiolite is often used for the production of absorbents, in the manufacture of pesticide or catalyst carriers, deodori-

zing agents, etc.

The great water retention capacity of sepiolite also accounts

for its plastic properties.

Sepiolite particles have anisometric, needle-like

structures, and occur agglomerated, forming bundles.

When these bundles are

dispersed in water or other polar solvents, the needle-like fibers are disagglomerated giving rise to a randomly intermeshed network of fibers of great volume which entraps the solvent. This results in suspensions of high viscosity and with rheological properties which depend on the concentration, the agitation employed, the pH and other factos.

These properties naturally make sepiolite

extremely useful as a suspension and thixotropic agent, and as a thickener.

263

As already mentioned, the active centers which exist on the surface of sepiolite, besides playing a large part in processes of sorption, can also be useful in certain catalytic reactions.

Sepiolite acts as a catalyst, for

example, in the conversion of ethanol to ethylene (Dandy, 1982) or may be used to break lactonic rings in the colour developing reactions in non-carbon required paper.

(TOLSA RESEARCH REPORT, 15-83).

Nevertheless, sepiolite has a very high chemical inertia. Its suspensions are affected very little by electrolytes, and its structure is not easily attacked by acids.' Owing to its chemical inertia, it can act as a carrier for pesticide or as an excipient for pharmaceuticals without altering the active substances themselves. Sorptive properties In its natural form, sepiolite is highly adsorbent and can retain up to

200 to 250% of its own weight in water.

The sorptive capacity of sepiolite di-

minishes when it is heated to above 300OC. (Migeon, 19361, due to structural changes that occur at that temperature and to the destruction of its porosity. Zeolitic water is found to be bonded by hydrogen bonds to the water coordinated to the magnesium ions at the edges of the structure (Prost, 1 9 7 5 ) .

These co-

ordination and zeolitic water molecules can be substituted by small molecules of high polarity.

The short chain primary alcohols for example, can penetrate

considerably within the channels, substituting the zeolitic and even the coordination water molecules (Fenoll and Martin Vivaldi, 1 9 7 0 ) .

The alcohols

of longer chain length can also substitute the zeolitic and coordination water molecules, but only in the open channels of the external surface. Sepiolite can also adsorb non-polar organic compounds, but it appears that this adsorption is limited to the external surface and depends on the size and shape of the sorbate molecules.

Studies of the free energy and enthropy changes

for the adsorption of linear and branched chain paraffins (Barrer, et al., 1954; Serna and Fernandez-Alvarez, 1 9 7 5 ) ,

suggest

that the molecules fit into the

open channels at the external surfaces. Rheological behaviour of sepiolite Although sepiclite is able to give stable suspensions of high viscosity at relatively low concentration, very few studies on its rheological behaviour have been carried out. The needle-shaped particles of sepiolite, as seen under an electron microscope, appear agglomerated, forming large bundles of fibers similar to brush heaps or haystacks.

These bundles are easily dispersed in water or other sol-

264

vents of high or medium polarity forming a random lattice of fibers that entraps the liquid. These suspensions of sepiolite have a Non-Newtonian behaviour that depends on many factors such as concentration of sepiolite, shear-stress, pH, etc., (Tolsa Research Report, 23-82). Sepiolite may form stable suspensions in non-polar solvents, but it is necessary to modify previously the hydrophilic surface of sepiolite with a surface active agent. Aqueous medium The rheological behaviour of sepiolite in high polarity media is related to the influence of factors such as:

-

Concentration

-

Concentration of sepiolite

-

Shear-stress

'

PH Pre-gel Electrolytes

The viscosity of sepiolite suspensions in water increases

markedly as the concentration of sepiolite increases as may be seen in the following table: PERCENTAGE OF SEPIOLITE

BROOKFIELD VISCOSITY

BY WEIGHT 2

AT 5 RPM (cps) 1,000

4

4,200

6

16,000

8

24,000

10

40,000

Treatment included stirring of the sepiolite suspensions at 8,000 rpm for 10 minutes. Shear-stress

-

Shear-stress affects the development of viscosity and the

rheological behaviour of the sepiolite gels. Shear is necessary to disagglomerate the fibers, and viscosity increases as the shear rate increases. The same occurs when shearing time is increased at a constant shear rate.

265

TABLE 1.

Development of viscosity of sepiolite suspensions

SHEAR RATE

TIME OF SHEARING

BROOKFIELD VISCOSITY at 5 rpm (cps)

(rpm)

(minutes

500

10

840

20

1,480

5

2,280

400

5

1,000

2,000

10

3,400

20

3,800

5

4,000

10

4,200

20

4,400

The conditions under which the sepiolite suspensionsare prepared, also influence the rheological behaviour of the suspension.

Under low shear stress

conditions the behaviour of the gel is rheopectic, but this behaviour reverts to

thixotropic when the shear stress is increased.

pH. - The viscosities of sepiolite suspensions remain relatively unaffected over a wide range of pH below 8 . The optimum pH, however, is 8 to 8.5, which is the pH at which sepiolite buffers the aqueous medium.

This buffering chara-

cteristic of sepiolite may be partly due to the leaching of Mg ions from the octahedral sheet of the sepiolite structure. At above pH 9 the viscosity decreases sharply and the rheological behaviour becomes Newtonian. Below pH 4 the crystalline structure of the clay begins to disintegrate and the stability and viscosity of sepiolite suspensions slowly disappear. Pregel. -

The possibility of improving the rheological properties of sepiolite

by first forming a pregel in part of the water have been studied, and the results have shown that the same viscosity results in the pregelified samples as in those obtained without forming pregel (Tolsa Research Report, 51-81). PERCENTAGE OF SEPIOLITE

BROOKFIELD VISCOSITY at 5 rpm (cps)

2% pregelified

4,600

2% not pregelified

4,600

8% pregelified

23,600

8% not pregelified

24,000

266

The formation of a pregel is therefore not advantageous.

Electrolytes.

-

Studies carried out on the effect of concentration and nature

of electrolytes on the rheological properties of sepiolite dispersions (Love11 and Rand, 1983) have shown that at pH 9 electrolytes have a very small effect on sepiolite suspensions, which may be a consequence of the probable isoelectric point of the edges at this pH.

At high pH, electrolytes flocculate the sepio-

lite suspensions and the rheological behaviour becomes pseudoplastic. Organic media The surface of sepiolite is hydrophylic due to the presence of a large number of "silanol" groups.

The hydrophylic character of the surface can be

modified by the adsorption of surface active agents, in order to make it compatible with slightly or non polar media.

The sorption isotherms of the cati-

onic surface-active agents, like the quaternary ammonium salts (specifically an alkyl benzyl dimethyl ammonium chloride) show that two distinct stages exist in the adsorption process.

In the first stage, the surfactant molecules are

adsorbed by a process of cation exchange, in quantities of approximately 10 meq/ 100 gr. of sepiolite, on the external surface; quantities of up to 35 meq/100 gr.

will continue to be adsorbed by a cooperative sorption process.

The coating of

sepiolite surfaces with these organic molecules will result in an organophilic sepiolite capable of forming stable suspensions in solvents with a low polarity, including aromatic solvents (Tolsa Research Report, 26-83). While it can be assumed that it is the presence of Van der Waals forces between the chains of the surfactant which modifies the surface, the gelification mechanism in non polar solvents is not yet clear. The relative reactivity of silanol groups may be used to obtain organic

derivatives of sepiolites by reaction with organic reagents which can form Si-0-C or Si-0-Si bonds. USES Absorbent capacity Sepiolite sorptive capacity is greater than that of any other clay. This, along with its mechanical resistance, which prevents disaggregation even in a satured state, permits its use in granular forms as an absorbent of water or

oil.

267

TABLE 2.

Absorption p r o p e r t i e s of S e p i o l i t e

GRANULARS ABSORBENTS GRANULOMETRY (ASTM)

6/15

6 I30

15 I30

30160

BULK DENSITY ( g / l )

450-500

450-570

530-570

550-600

WATER ABSORPTION (FORD TEST)

80- 90

95-105

105-1 15

110-12'0

O I L ABSORPTION (FORD TEST)

65- 70

75- 8 0

80 -90

90-100

SAE 10 O I L ABSORPTION (WESTINGHOUSE TEST)

60- 65

70- 75

75- 85

85- 95

SAE 20 O I L ABSORPTION (WESTINGHOUSE TEST)

55- 60

65- 70

70

-

80- 90

--

3.5-4.0

--

12+-3

12+-3

SHELL I N D E X , KG/CMZ

MOISTURE ( X )

12+-3

80

---12+-3

(Tolsa Technical Data Sheet, 23-82). S e p i o l i t e a l s o has a high c a p a c i t y t o absorb humidity and organic vapors. Although i t s i n i t i a l absorbent r a t e is l e s s than t h a t of s i l i c a g e l o r a c t i v a t e d alumina i t can absorb such organic l i q u i d s a s hesan, benzene, and methyl alcohol with a considerably g r e a t e r c a p a c i t y (Robertson, 1957). BENZENE

VAPOUR

TIME

H E M E VAPOUR

HOURS

Sep. Si02 A 1 2 0 3

Sep.

SiOz

A1203

3

11.0 18.5 12.0

---

---

24

27.6 26.4 23.1

40.9

120

27.3 27.3 24.6

480

45.6 27.3 25.4

METHYL ALCOHOL Sep.

Si02 A1203

___-

16.4

22.9

10.7

28.9

25.0

26.5

30.4

23.8

58.6

30.1

28.7

33.6

31.5

25.7

60.7

31.7

31.3

45.2

31.9

27.0

S e p i o l i t e can be used as an absorbent i n i t s n a t u r a l form, o r a c t i v a t e d by h e a t i n g between 200 and 300"C, which removes t h e hygroscopic and z e o l i t i c water without reducing appreciably i t s s u r f a c e a r e a and i n c r e a s i n g i t s s o r p t i v e properties. Environment deodorant S e p i o l i t e has a high c a p a c i t y t o absorb molecules r e s p o r x i b l e f o r foul

268

odours, as sorption studies have shown. The sorption curves of 1.4 diaminobutanes fputrescine), 1.5 diaminopentane (cadaverine), both responsible for the foul odour of putrescent flesh, fndole and butanal, involved in the foul odour of faeces, on sepiolite, palygorskite, and synthetic tobermorite show that in all cases, sepiolite was the most rapid and effective sorbent. The rate of sorption of 1.4 diaminobutane and 1.5 diaminopentane is particularly rapid.

These molecules and those that have ammonium groups or various nitro-

gens in their structural composition may react with the Bdnsted and Lewis sepiolite acid centers. p e butanal, which is absorbed in a lesser quantity than the amines, may possibly be absorbed forming hydrogen bonds with the i>C=O groups (Tolsa Research Report 33-82). The great capacity of sepiolite to reduce the environmental concentration of gaseous NH3 from an initial concentration of 100 ppm to 18 ppm at a rate of 40 gr. of sepiolite/m3, has also been proved (Tolsa Research Report, 28-81). For this reason, sepiolite is suitable for the control of NH3 levels in intensive animal farms where, as studies using rabbits and other animals, have shown, ammonia is a risk factor. Catalvst carrier The great majority of catalysts used in industry are impregnated on a support with a good mechanical and thermal stability and with a large surface area.

Sepiolite in its natural form conforms to these specifications, having

a good mechanical and thermal resistance, as well as a large surface area (350 to 400 mz/gr.) that can be varied by the use of acid and thermal treatments. The catalyst can be impregnanted on the surface and can also substitute part of the magnesium cations in the octahedral sheet of the structure of sepiolite by treatments with a salt of the metal at pH 7 (Oguchi, 1978). Sepiolite can be used in supporting Zn, Cu, Mo, W, Fe, Co and Ni, among other compounds, in demetallization and deasphalting processes as well as hydrodesulfuration or hydro-cracking (Ioka, 1977a). Sepiolite can support Ni, Co or Cu and a fluoride of an alkali or alkaline earth metal during the hydrogenation of unsaturated C=C unions in olefins or aromatic compounds (Miyata and Sato, 1973). Supporting a metal of the group Co, Ni, Fe, Zn, Cu or other metals belonging to the lanthanoid series, and another of the group Mo, W, V, Ni, Co and Cu, it can be used for hydrogenation, desulfuration, denitrogenation or demetallization processes (Ioka, 1977b).

As a support of Mn, or of Mn and of Cu or Zn conjunctively, it can be used in the production of butadiene from ethanol (Kitayama and Wada, 1980). Sepiolite

269

is used also to obtain hydrocarbons from methanol as a support to A1 and Mg

-

(Kitayama and Wada, 1 9 8 1 ) . , Other applications are: in the hydrogenization of gasolines obtained by cracking, containing,unsaturatedor aromatic hydrocarbons where sepiolite is a carrier for Ni (Carrpthersm Lawrence, 19651, for the hydrogenation of an alkadiene in a monoolefiq (Bourne Holmes, 1 9 6 3 ) , in the isomerization of olefins (Howman, 1 9 6 4 ) ; and finally, sepiolite acts as a carrier for Ni or Co in hydrocatalytic cracking of n-alkanes containing 10 or more carbon atoms (Globe and Fletcher, 1964)': Polyesters Sepiolite can be ,used in liquid polyester resins as a thickening and thyxotropic agent, preventing pigments settling, and sagging of the polyester resins after application. In order to use sepiolite in these organic media it is necessary to make the hydrophilic surfaces of sepiolite compatible with the polyester, modifying

it with a surface active agent which will not interfere with the activators and catalysts used in the polymerization of the resin. The following illustrates the viscosity of sepiolite modified with a quaternary ammonium salt in Estratil A1-100, and its thixotropic index (Tolsa Research Report, 37-83). TABLE 3. Viscosity and thixotropic index of modified sepiolite MODIFIED SEPIOLITE

BROOKFIELD

BROOKFIELD VISCOSITY

THIXOTROPIC INDEX

z

(rpm)

(cps)

2.5 rpmI20 rpm

0.5

2.5

20 1 .o

2.5 20

2.0

2.5 20

3.0

2.5 20

1,600

1.23

1,300 2,400

1.57

1,525 9,400

2.87

3,275 16,000 5,450

2.94

270

Asphalt coatings Asphalt coatings that are employed in roof or underbody coatings, basically contain two components: asphalt cutback, which can have a solid matter content from 50 to 70% and consists of the heaviest crude oil fraction, and asbestos. Asphalt is frequently employed due to its low cost in the sealing of voids and cracks.

In order to achieve an adequate consistency asbestos is used, which

also provides reinforcement of the film and valuable insulation. However due to the possibility of health dangers resulting from the use of asbestos, there is a tendency to use other products. A suitable substitute for asbestos is sepiolite, because of its harmlessness. Moreover, sepiolite, owing to its thickening and thixotropic characteristics, improves the handling of the finished product, allowing its use in sprays, which is difficult when asbestos is used. Paints Paints are basically systems consisting of a medium such as water, oil or latex (or various other organic chemicals) in which a series of solid products called pigments are suspended and whose function is to provide colour and certain film properties such as hiding power, film strength and resistance to weathering. Organic additives such as cellulose and inorganic additives such as clays, whose function is to impart certain rheological properties to the paint, can also be added.

Sepiolite can be included among these additives, because it

acts as a suspending agent and prevents pigment settling during storage.

Sepio-

lite acts as a thickening agent as well, providing the suitable viscosity, and as a thixotropic agent, providing easy application for its use with brush, rollers or air or airless spray equipments, and it provides hiding at all pigment volumes concentrations, good gloss, good stain removal and scrub resistance, antisag and leveling properties, and good heat stability. Regarding the organic additives, sepiolite has the advantage of not acting as a substratum for the growth of fungi, and its viscosity is not modified by hard water or temperature. Studies of the behaviour of sepiolite in comparison with commercial american attapulgites using acrylic and polyvinyl acetate latex paints show that similar results are obtained using only half the concentration of sepiolite (Tolsa Research Report, 29-83). Sepiolite can also be used as a thickening and thixotropic agent in paints with an 0rgani.c carrier, after modification of its surface with surface active agents. Pharmaceutical uses Sepiolite can be used as a pharmaceutical excipient thanks to its large active area, on which the active product can be retained. Degradation of the active products in different clays is produced by oxidative reactions catalyzed

271

by adsorbed iron at the clay surface as well as structural ferric iron near the clay surface or by acid hydrolysis processes whereby the surface of the clay serves to concentrate the active product by sorption of protons and by cation exchange. The low exchange capacity, as well as the low content of surface ferric iron of sepiolite, allow its use as pharmaceutical excipient for drugs which undergo oxidative degradation.

In the same way, the favourable sorbent characteristics of sepiolite can be applied to its use as gastrointestinal adsorbent of toxines, bacteria and liquid in the treatment of diarrhoea1 processes. The gel-forming property of sepiolite also allow its use in the protection of intestinal mucous membranes, coating the intestinal walls and stomach. Furthermore, its capaiity to control pH, as shown in comparative studies of mixtures of sepiolite and MgO, and mixtures with A1 (OH) and tri-silicates 3

magnesium, allow its use as an antiacid product in the treatment of gastric acidity (Tolsa, Research Report, 39-82). Decolorizing agent Clays are used widely in the decolorization of paraffin, greases and mineral and vegetable oils. The distinct processes of decolorization are: retention during filtration or percolation of coloured particles; absorption of coloured substances; and the catalytic conversion of coloured compounds in to noncoloured or easily absorbable compounds. Sepiolite is used as deodorizer, dehydrant, neutralizer and decolorant in contact processes, where the oil is treated with sepiolite, and later filtered or in percolation processes in which the oil is passed through a 10/60 mesh sepiolite granule. A decolorizing clay with a high decolorant capacity should naturally have a low retention of oils and very good filtration characteristics. Chambers (1959) has pointed out the excellent decolorizing characteristics of sepiolite, also noting that the addition of small quantities of sepiolite, to normal bleaching earths will improve filtration characteristics. Dandy (1967) has shown that sepiolite has a high bleaching activity on cotton seed oil, and that this activity is lowered upon pre-heating the sepiolite from 100 to 50OOC. This suggests that micropores play an important role in the absorption of coloured compounds. The fact that sepiolite has a greater decolorant activity with respect to

. mineral than to vegetable oils confirms that porosity plays an important role in the decoloration process. The coloured compounds in vegetable oils are commonly molecules of considerable size such as chlorophyll, carotenes and xanthophylls which cannot penetrate into the channels and pores of sepiolite.

272 On the other hand, the coloured compounds in mineral oils are simple molecules,

generally naphthenic derivatives, which can penetrate into sepiolite pores (Chambers, 1959). The favourable bleaching capacity of sepiolite can be attributed to its high surface area and to the existence of sorption and chemisorption processes. With regard to work conditions, these will depend on the type of oil, although 1 to 2% of sepiolite is often used.

The work temperature is 9O-llO0C, given

that high temperatures lower the viscosity of the oil and activate the chemisorption processes.

In contact processes, 35 to 40 minutes is the common time

(Tolsa Technical Data Sheet, 1 2 - 8 0 ) . Filter aid The specific needle-like form of sepiolite particles may make it very useful as a filter aid because they give rise to open-random-network structures which make the filter cake more porous and, as a result, increase filtration rate. The capacity of sepiolite to aid filtration can be utilized along with its sorpcitive properties for the decolorization of oils and as a clarifying agent in processes such as glucose-production (Chambers, 1959). Anticaking Because of its large specific surface area on which sorption and semisorption processes take place, sepiolite can retain various kinds of liquids in elevated proportions while also acting as an anticaking and free flow agent controlling the humidity of the mixture, or coating the surface of the product to be fluidified (Tolsa Research Report, 1 4 - 8 2 ) . Phytosanitary carrier Most pesticides are chemical substances with high activity levels that must be applied in small quantities to large areas. For this reason, they need carriers or diluents in solid or liquid form. Using granular substances a s diluents or carriers provides a better handling of the product, which can be better spread even during wind conditions.

Sepiolite can be applied simultaneously with

cultivation, seeding or fertilizers operations, slowly releasing the toxic chemical, over a longer period of time.

One of the most important characteristics

required for a pesticide support is that it must guarantee the stability of the chemical.

Generally, pesticide deactivization processes are attributed to

face catalytic activity of the carrier being used. ved highly acid sites on the surface.

SUP

In this activity are invol-

The pka determined in natural sepiolite

obtained by Beneri technique Estrada and Espinosa de les Monteros, 1969).

is of 3 . 2 0 to 1.52 (Alvarez Since surface acidity loses its

deactivating effect for formulation when the pka reaches values close to 4 ,

273

sepiolite surfaces are then slightly acid and exert only low activity in the presence of the pesticide.

Another important factor for stability is CEC and

the type of the exchanged cations. ?he common exchange cations in sepiolite (Na, K, Mg and Ca) have a very low deactivating activity. Studies carried out regarding the decomposition of Endrin DDT, Malathion, Lindane and Sevin, have shown that only Endrin and Malathion are unstable in the presence of sepiolite. Even

so,

their half-time decomposition is very slow

(Alvarez Estrada and Espinosa de 1 0 s Monteros, 1970). t1/2

decomposition in days

SEPIOLITE +

25OC

40°C

60°C

80°C

25% ENDRIN

1.774

268

30

4 .O

SEPOLITE +

50°C

70°C

90°C

25% MALATHION

70

20.2 hours 160 minutes

It is important to note, however, that if the toxicant is very sensitive and can be deactivated to pka

- 4, the surface acidity of the sepiolite can

be eliminated with urea, ethylene glycol or hexamethylene tetraamine. Another important Characteristic of the carrier must be its capacity to maintain free flow after the pesticide has been absorbed. Again, owing to its high surface area, sepiolite can absorb liquid or solid toxicals of low melting point without losing its free flow, actually providing higher flowbility even after 45% malathion had been absorbed.

(Tolsa Technical Data Sheet, 16-80).

Another useful characteristic of sepiolite is the easy release of active chemicals in the presence of water as shown in retention studies u s i n g 2-4-dichlorophenoxyacetic acid (Lopez Gonzalez et al., 1974).

In addition, sepiolite has its own insecticide properties as studies on "Musca domestica" and "Tribolium Castaneum" have shown.

This effect is attributed

to the abrasive action on the cuticulae of the insect supplemented by the absorption of its lipoids and of water in the epiticule, causing rapid death of the insect. Cigarette filters Tobacco smoke consists of a large number of droplets 0.1 to 1 that are suspended on a gaseous phase.

J.I

in diameter,

The gaseous phase is composed of gases

such as carbon dioxide and carbon monoxide, products of the distillation of paraffin waxes, terpenes, aromatic substances, and pyrolisis products from polypeptides and polysaccharides.

Cigarette filters can act in a mechanical way,

274

as for examples cellullose acetate filters that retain the droplets of the smoke without affecting the gaseous substances. Another type of filter uses substances such as activated carbon, which allow the unselective sorption of the gaseous substances of the smoke, due to their large sorptive surface areas (Artho

et al., 1 9 7 2 ) .

Studies done on the sorption of gaseous components in cigarette

smoke using sepiolite and activated carbon (Esp. Pat. 352013) show that sepiolite not only activates a very thorough sorption of the gases found in cigarette smoke, but that this sorption i s selective.

That is, the polar gaseous compounds

such as nitriles, acetone,.acrolein and others, which are endangering health are preferentially adsorbed. On the other hand sepiolite adsorbs to a lesser degree the less polar compounds such as aromatic substances methylfuran, dimethylfuran or limonene, for example, which greatly enhance the flavour of tobacco. Plastisols Plastisols are dispersions of fine PVC (polyvinyl chloride) particles in one or various plasticizers which can also carry pigments, fillers and stabilizers, etc.

A plasticizer is selected according to the functional properties re-

quired in the finished product.

The use of paraffin or chlorinated diphenyls,

for example, will retard flammability and the use of dioctyl phtalate and chlorinated paraffins improve the electrical and mechanical properties.

Plasti-

sols can be applied through dip application, or by spray and other means. plasticizers are cured by heating at temperatures up to 160 to 180°C.

The

Under

higher temperatures than these, the PVC particles swell up to a point where all the plasticizer is absorbed.

If one continues to increase the temperature the

PVC dissolves in the plasticizer until it forms a homogeneous phase.

If the

temperature is decreased, a solid, homogeneous product results which is resistant and flexible thus providing a product that may be used in a variety of applications, from underbody coatings to a wide range of uses in the toy industry. In order to obtain a stable, homogeneous paste with thyxotropic properties and suitable for application by spray without dripping, sepiolite modified with surface active agents can be used, giving comparable results to other thyxotropic agents such as organophilic bentonites and pyrogenic silicas. These results were .obtained in studies on the rheological behaviour of suspensions of Organophilic Bentonite, Sepiolite and Pyrogenic silica in a typical plasticizer

such as DDP (Tolsa Research Report, 11-82).

275

TABLE 4.

R h e o l o g i c a l b e h a v i o u r of s e p i o l i t e compared t o t h a t of o t h e r thixotropic agents

PVC MIRWL P-207 DDP

Epoxized soybean o i l

100

100

100

100

100

100

75

75

75

75

75

75

5

5

5

5

5

5

3

3

-

-

-

-

-

5

5

Nuostabe V-1788

3

3

3

American A t t a p u l g i t e

-

5

-

-

Organophil i c Benton it e

-

5

-

Pyrogenic S i l i c a

-

-

-

2.5

-

S e p i o l it e

3

Monazoline 0 C h l o r i d e Salt

Methyl Alcohol BROOKFIELD VISCOSITY 2.5 rpm

4000

165000

16800

62000

168000

120000

20 rpm

3900

67000

9600

48000

90000

45000

1.02

2.46

1.87

2.67

THIXOTROPIC

*

INDEX*

1.75

1.29

V i s c o s i t y a t 2.5 rpm

V i s c o s i t y a t 20 rpm

Rubber The f i l l e r s used i n r u b b e r can b e c l a s s i f i e d a c c o r d i n g t o t h e i r o r g a n i c o r inorganic composition.

P r e s e n t l y two t y p e s of i n o r g a n i c f i l l e r s a r e used:

chemical p r e c i p i t a t i o n p r o d u c t s such as p r e c i p i t a t e d s i l i c a and micronized o r moltured n a t u r a l p r o d u c t s , among which s e p i o l i t e i s i n c l u d e d . a l s o b e c l a s s i f i e d as r e - i n f o r c i n g ,

The f i l l e r s , can

s e m i - r e i n f o r c i n g and d i l u e n t s .

Due t o i t s

g r e a t s u r f a c e a r e a and t h e e x i s t e n c e of s i l o x a n and s i l a n o l groups which can develop a c e r t a i n a c t i v i t y i n t h e p r e s e n c e of e l a s t o m e r s , s e p i o l i t e can f u n c t i o n a s a semi-reinforcing f i l l e r .

However, t h e s e groups c a n a l s o a b s o r b p o l a r pro-

d u c t s such a s a c c e l e r a t o r s and t h i s n e c e s s i t a t e s t h e u s e of a c t i v a t o r s such a s t r i e t h y l a m i n e o r p o l y e t h y l e n e g l y c o l whose s o r p t i o n e n e r g y i s g r e a t e r than t h a t of t h e a c c e l e r a n t . S t u d i e s on t h e b e h a v i o u r of s e p i o l i t e a s a f i l l e r i n SBR ( S t y r e n e , Butadiene Rubber), NR ( N a t u r a l Rubber), CR ( C h l o r o p r e n e ) , NBR ( N i t r i l i c Butadiene Rubber) and EPDM ( E t h y l e n e P r o p i e n e Diene Monomer) r e c i p e s i n comparison t o t h e commer-

276

TABLE 5.

Properties of sepiolite as a f i l l e r . PRECIPITATED SEPIOLITE

S M R 5 cv SEPIOLITE ULTRASIL VN-3 HEXAFIL N-762 CIRCOSOL 4240 TEA ZINC OXIDE STEARIC ACID SANTOWHITE 54 SULPHUR MBTS DPG

100 61

-

2 6 5 1 1 2.5 1.5 0.8

SILICA

KAOLIN

100 61

100

-

2 6 5 1 1 2.5 1.5 0.8

-

72 2 6 5 1 1

2.5 1.5 0.8

CARBON BLACK 100

-

50 2

-

5 1 1 2.5 1.5 0.8

MOONEY AT 121 C' Minimum viscosity

46

100

28

30

RHEOMETER AT 140'C 2'0"

T 2- minutes

minutes

1'42"

1'18"

4'30"

11

12

12

6

TmaxLbxinch

52

73

37

44

1 Lbxinch

42

51

32

40

78 57 46 1.8 21.6 420 7.6 17.0

90 55 34 1.7 24.7 630 2.7 7.3

64 72 39 0.5 23.1 510 3.0 6.2

64 83 21 0.5 22.0 440 2.9 11.5

90

93

90

60

76

71

56

43

tgO

PHYSICAL-MECHANICAL PROPERTIES Hardness (Shore A) Resilience (%) Compression set (22h/70°C) Smooth tear, K g / m Tensile strength, Mpa Elongation at break X 100% Modulus, ME'a 300% Modulus, MPa AGEING (5 days185 "C) Aged tensile, % ret. AGEING (10 days185'C) Aged tensile, Z ret.

TOLSA TECHNICAL DATA SHEET 16-82

277 cia1 kaolins (Gonzalez Hernandez, L., et al., 1977) show that the TEA/sepiolite mixtures used in SBR rubber result in higher modules, tensile strength, hardness and tear resistance and better ageing behaviour. In nitrilic rubber (NBR), EPDM and CR, Sepiolite improves all of these properties except the elongation at break and resilience. Sepiolite, then, together with a cheap activator, is extremely useful in producing vulcanized rubber with better mechanical properties than can be obtained with similar fillers. (Tolsa Research Report, 9-83). I n general, it 'produces an increase in the reinforcing power with respect

to kaolin in the values of the modules, tear resistence and abrasion loss. increase of the crosslinking density decreases the elongation at break.

The

It has

also been observed that sepiolite improves the ageing behaviour. The compatibility of the inorganic surface of sepiolite with the organic matrix of the polymer by bondin:, bifunctional compounds such as silanes or titanates to the silanol groups on the sepiolite surface, allows the use of sepiolite as a reinforcing filler. The addition of y - m e r c a p t o p r o p y l t r i m e t h o x y s i l a n e to sepiolite in SBR, NR, NBR, EPDM and CR recipes (Gonzalez Hernandez et al., 1977) allows to obtain better properties than using other fillers such as precipitated silica. Animal nutrition Thanks to its characteristic sorptive properties, free flow, anticaking and to its chemical inertia and atoxicity, sepiolite in its various granular forms may be used in the field of animal nutrition (Alvarez and Perez Castella,

1982).

Outstanding in this type of use are the following applications:

-

growth promoters

-

component of h i d e concentrates supplements

-

binder of feed

-

stimulation of production

carrier for supplements

Growth promoters Experimental tests carried out on the effect produced by sepiolite in cattle and poultry feed show that sepiolite in concentrations from 0.5% to 3% improves the feed efficiency up to approximately 7% in pigs and up to 10% in broilers and rabbits.

Increases of 6-7% in rabbit1 weight were also noticed.

The use of sepiolite as binder of feed provides a better feed efficiency than that obtained with other binder such as lignosulphonate. This feed efficiency improvement could be a consequence of the digestibility increase of the protein

278 produced by a slower flow of feed through the intestinc duc to the formation of a gel.

Sepiolite, due to its sorptive properties, may control the ammonium

levels, thus preventing intoxications or chronic diseases caused by ammonia. In the same way sepiolite can control diarrhoea produced by toxines or specific amines, thanks to its m o n i a and amines absorption, the foul odaur of faeces diminishing as well. Carrier of supplements Addition of vitamins, minerals, antibiotics, etc.. to feed is a widely used technique. l'he problem which the manufacturer faces is to make the microingredients dosificable. Sepiolite used in a particle size 60 to 120 mesh (ASTM) qualifies as a carrier with a good homogenization of the micro-ingredients.

A

series of factors such as dustiness, bulk density, size, shape, surface and electrostatic charge of sepiolite are essential in order to avoid the aggregation of the components. Other characteristics not less important than the former are the chemical compatibilitywith the zicro-ingredients. Since sepiolite is not too hygroscopic, nor does it produce extreme pH in the presence of water, it ensures the stability of the components. A series of physiological and veterinary tests carried out to determine the effect of sepiolite on intestinal absorption of vitamins and minerals show that sepiolite is chemically inert in relation to microingredients, without affecting their intestinal absorption. The free flow and anticaking properties of sepiolite facilitate the packing, transport and storage of the product. Binder of feed From studies carried out with sepiolite, bentonite, lignosulphonate and other binders it has been concluded that sepiolite behaves better as a binder than the other products.

It may be used to pelletise fish, poultry, lamb feeds

and for all general kinds of feed, from very fatty ones like those used for pigs to very fibrous ones used for rabbits. The pellets obtained with sepiolite give a durability of 95%. The fluid action of the clay permits the use of lower temperature and force than those used with other binders.

This factor is very important considering the possible

hydrolysis of vitamins, proteins, etc... at-high temperatures. This constitutes an appreciable saving of energy during the fabrication process. Detergents The use of clays in detergent and cleaning compounds has been investigated in recent years and clays with a high exchange capacity are being used as softeners of hard-water, exchanging Ca and Mg ions in water for their own cations.

279

Clays with a low exchange capacity are used as free flow agents, and clays modified with non-ionic surface active agents may also be used as fabric softeners. By 1942, Fleury-Larsenneau and Andre had already established that the substitution of up to 30% of fatty acids by sepiolite improved the efficiency of soaps in washing tests. The data obtained show that sepiolite has more detergent action than montmorillonite or kaolinite. Recent studies carried out using sepiolite, and sepiolite modified with certain organic compounds, in detergent compositions (Tolsa Research Report, 3-83) have shown that sepiolite not only improves the quality of cleaning and

removal of stains but also improves the final whiteness by up to 1 to 2 units on a scale of 0 - 4 (Tolsa Research Report, 1 8 - 8 3 ) .

This effect may be due to the

sorptive characteristics of sepiolite that may act keeping the dirt in suspension. Thanks to these sorptive properties, sepiolite may also absorb bacteria and to a lesser degree fungae present in the cloth or in the washing water (Tolsa Research Report, 21-83). TABLE 6 .

Properties of sepiolite used in detergents EXPERIMENTALLY CONTAMINATED WATER (cell/ml)

WATER TREATED PERCENTAGE OF WITH 2% SEPIODECREASE LITE AT 1 5 ° C 2h (cell/ml) (X)

Total mesophile 656000

193000

70.58

aerobian bacteria

280

40

85.71

Fungus

134

67

49.81 91.54

aerobian bacteria Sporuled mesophile

Enterobacteria

1 100000

93000

Pseudomona

4600GOO

930000

79.78

4300

1500

65.12

Streptococcus Sulfite reducing Clostridium spores

9500

2500

73.63

E. Coli

268000

11000

95.90

Micrococcus

495000

105000

B. Cereus

600000

---

78.78 100

Finally the rheological properties of sepiolite also allow its use as suspending agent in liquid detergent compositions.

280

Cosmetics Sepiolite may be used in cosmetic products as a thickening and thixotropic agent, providing a suitable viscosity to pastes and creams.

Sepiolite can also be

used as a pigment suspension agent and thanks to its sorptive properties is even able to function in some instances as an active absorbant substance of grease and bacteria. Among other advantages, it is not necessary to pregelify sepiolite in order to develop its suitable rheological properties and the viscosity of its suspensions increases with increasing temperatures of the aqueous phase, which is useful in the preparation of the cosmetics. Additives such as propylene-glycol, sorbitol, glycerol or ethyl alcohol may be used to impart humectant and preservative properties, without affecting the viscosity of suspensions of sepiolite. Among the many products in which sepiolite may be used are (Tolsa Research Report, 22-82, 41-83,

-

Tolsa Technical Data Sheet 3 0 - 8 3 ) :

Fluid emulsions: increasing consistency when sepiolite is added to the aqueous phase.

- Masks: used as an active substance in the treatment of greasy skin and acne.

-

Tooth paste:

sepiolite provides adequate consistency and acts as a bacterial

absorbent besides substituting part of the abrasive compounds.

-

Cream make-up:

sepiolite acts as a suspending agent allowing a better pigment

distribution in the oil phase.

-

Dry shampoo:

sepiolite absorbs oil and dirt.

Agriculture Recent studies suggest that sepiolite may be used in the field of agriculture, taking advantage of its sorptive properties and its ability of forming stable suspensions. For example, it may be used in:

2.

-

3.

-

Seed coating

4.

-

Fertilizer suspensions

1.

Soil conditioning Fluid carrier for pregerminated seeds

Soil conditioning Soils must have good aeration which depends on the macroporosity of the earth.

It also must be able to retain water, ions, nutrients, fertilizers, etc.

This ability is also directly related to the macroporosity of the particles which compose the soil. With suitable granulometry such as 6 / 1 5 , 3 0 / 6 0 mesh ASTM sepiolite can be easily homogenized with soil and may provide the soil with the required porosity,

281

improving drainage and aeration. The existence of high macroporosity in sepiolite allows it to retain great quantities of water and nutrients which can be supplied to the plant.

The calcination of sepiolite can improve its mechanical resistance

to disintegration in water or under pressure and improve its sorptive capacity. Fluid carrier for pregerminated seeds The classic systemsof seeding in which the seeds are introduced in furrows and germinated in the same soil produce a low yield of about 4 0 % . In the seeding by fluid systems the seeds are pregerminated in tanks with a suitable nutrient medium at adequate temperature.

Then, the pregerminated

seeds are applied in furrows, suspended, in the aqueous medium.

This technique

allows an increase of up to 8% of the yield. This type of seeding demands a suspending agent in order to keep the seed suspended in the aqueous medium.

In concentrations of 4 to 5%, sepiolite pro-

duces stable suspensions for the duration of the required time in order for the radicule of the seed to be inserted in the ground.

Furthermore the water in

sepiolite suspensions, is easily available t o the radicule as indicated by the low psychrometric potential values of the sepiolite gels (Tolsa Research Report, I

32-83).

This particular method of seeding also permits the addition of nutrients, fertilizers or pesticides which are gradually administered to the plant. Seed coating Another seeding system that may improve yields is seed incapsulation, which allows the incorporation of pesticides and fertilizers within the capsule itself. Micronized sepiolite, up to a particle size of 5 pm can be used In the coating of the seed.

The coating disintegrates on water contact, freeing the seed, which

can then use the compounds incorporated in the capsule (Tolsa Research Report, 48/82).

Fertilizer suspensions Fertilizers in suspension have an advantage over fertilizer solutions since the concentrations of the nitrogenous compounds, as well as the phosphorous or potassium compounds, are not restricted by their solubility, These fertilizers need a suspending agent that will keep insoluble products in suspension. The rheological properties of sepiolite and its viscosity at low values of pH provide these necessary requirements for fertilizer suspensions (Tolsa Research Report, 3 2 - 8 1 ) .

282

Grease thickener S e p i o l i t e mod_ified with a s u r f a c e

a c t i v e agent required t o make i t s s u r f a c e

hydrophobic can be dispersed well i n mineral o i l s i n o r d e r t o o b t a i n l u b r i c a n t greases of high v i s c o s i t y .

S e p i o l i t e modified with an a l k y l d i m e t h y l b e n z y l a m o n i u m

c h l o r i d e can be dispersed a t 15% i n d i i s o o c t y l Adipate, S i l i c o n e 500 and a mixt u r e of mineral o i l w i t h polybutene a t 50% r e s u l t i n g i n greases of high v i s c o s i t y (Tolsa Research Report, 4 3 - 8 2 ) .

BROOKFIELD VISCOSITY

SOLVENT

AT 5 Diisooctyl a d i p a t e

rpm (cps)

1,120.000

Mineral o i l with p o l i butene (50%)

520 .OOO

10% suspensions of organophilic s e p i o l i t e

No carbon required (NCR) paper

NCR papers produce copies without having t o use carbon paper.

f a s t and good q u a l i t y p r i n t i n g without high p r e s s u r e . of two o r t h r e e s h e e t s . sheet a r e required.

They o f f e r

Such paper may c o n s i s t

In t h e f i r s t c a s e , a CB t r a n s f e r s h e e t and a CF r e c e i v i n g

In the l a t t e r case, a t h i r d transfer-receiving sheet i s

coated on i t s back s i d e with microcapsules which enclose a c o l o u r l e s s intermediate dyestuff such a s CVL ( c r y s t a l v i o l e t c a r b i n o l ) o r a blue BLMB (n-Benzoylleucomethylene).

The CF r e c e i v i n g s h e e t has a c o a t of developing pigments which can be

organic such a s phenolic r e s i n s , o r inorganic such a s c l a y s .

During t h e p r i n t i n g

process, upon p r e s s u r i z i n g t h e CB l a y e r , t h e microcapsules a r e broken.

The dye

precursor i s then r e l e a s e d onto t h e r e c e i v i n g f a c e of t h e CB s h e e t where t h e e l e c t r o n donor-acceptor r e a c t i o n s occur on t h e developer. transformed i n t o a coloured molecule.

Thus t h e precursor i s

I n t h e case of CVL, f o r example, t h e

lactone s t r u c t u r e i s broken, r e a c t i n g w i t h an a c i d c e n t e r which forms a t r i phenylmethyl c a r b a c a t i o n , s t a b i l i z e d by mesomerism, of an i n t e n s e b l u e colour. In t h e BLMB c a s e , on t h e o t h e r hand, h y d r o l y s i s of t h e amide i s produced.

Later,

an oxidation r e a c t i o n occurs which produces methylene blue. S e p i o l i t e can be used a s a developer thanks t o i t s Lewis a c i d c e n t e r s a r i s i n g from t h e s u b s t i t u t i o n of S i atoms i n t h e t e t r a h e d r a l s h e e t by t r i v a l e n t atoms. The abundant s i l a n o l groups on t h e s e p i o l i t e s u r f a c e a r e BrHnsted-Lowry a c i d c e n t e r s which a l s o may act in t h e r e a c t i o n .

The l a r g e s u r f a c e of s e p i o l i t e

allows t h a t , a f t e r colour development, t h e c o l o r a n t molecule remains absorbed

on t h e s e p i o l i t e s u r f a c e f i x i n g and guaranteeing permanent c o l o u r (Tolsa Research Report, 15-83).

283

~ e s i d e sb e i n g a c a t a l y s t c a r r i e r , s e p i o l i t e i t s e l f h a s a l s o c e r t a i n c a t a l y tic activities.

T h i s h a s been shown i n s t u d i e s i n which e t h y l e n e had been ob-

t a i n e d from e t h a n o l , w i t h s e p i o l i t e s e r v i n g a s a c a t a l y s t (Dandy, 1 9 8 2 ) . Drilling fluids I n d r i l l i n g o p e r a t i o n s by t h e r o t a r y method a f l u i d is c i r c u l a t e d c o n t i n u o u s l y i n o r d e r t o e l i m i n a t e c u t t i n g s produced i n t h e d r i l l i n g .

The d r i l l i n g f l u i d

i s pumped down from a mud t a n k o r p i t through t h e hollow d r i l l stem and emerges through small o r i f i c e s i n t h e b i t a t t h e bottom of t h e h o l e .

It t h e n r i s e s up-

ward through t h e a n n u l a r s p a c e s i t u a t e d between t h e walls of t h e h o l e and t h e d r i l l stem f o r c i n g t h e d r i l l c u t t i n g s o u t . On t h e s u r f a c e t h e mud i s c l e a n e d of c u t t i n g s by t h e u s e of a s i e v e o r by a l l o w i n g t h e c u t t i n g s t o s e t t l e i n t o t h e mud p i t . function:

1)

The d r i l l i n g mud h a s a t r i p l e

t o remove t h e c u t t i n g s produced d u r i n g d r i l l i n g ,

and c o o l t h e d r i l l p i p e , and 3 )

t o lubricate

2)

t o form a n impervious c o a t i n g on t h e w a l l of

t h e d r i l l e d h o l e i n o r d e r t o p r e v e n t w a t e r p e n e t r a t i o n from t h e d r i l l i n g f l u i d i n t o t h e formations.

T h i s c o a t i n g must be t h i n s o t h a t i t does n o t i n t e r f e r e

with t h e d r i l l i n g operation. The d r i l l i n g mud must h a v e c e r t a i n r h e o l o g i c a l p r o p e r t i e s .

I t must b e t h i -

x o t r o p i c w i t h c e r t a i n g e l s t r e n g t h when t h e mud i s n o t i n motion i n o r d e r t o avoid s e t t l i n g of t h e d r i l l c u t t i n g s when pumping of t h e d r i l l f l u i d ceases temporarily.

I t must a l s o be e a s i l y pumpable.

I t s p r o p e r t i e s f u r t h e r m o r e , must

be s t a b l e and change l i t t l e d u r i n g t h e p r o c e s s under t h e h i g h t e m p e r a t u r e s produced d u r i n g t h e deep d r i l l i n g s and i t s h o u l d be

l i t t l e a f f e c t e d by l a r g e

v a r i a t i o n s i n t h e c o n c e n t r a t i o n s of e l e c t r o l y t e s e n c o u n t e r e d i n t h e d r i l l i n g process.

Clay s u s p e n s i o n s a r e used a s d r i l l i n g f l u i d s (Grim, 1 9 6 2 ) .

Sepiolite

h a s d e f i n i t e a d v a n t a g e s o v e r o t h e r c l a y s such a s b e n t o n i t e i n s a l i n e w a t e r d r i l l i n g f l u i d s e s s e n t i a l l y due t o i t s minimal s e n s i t i v i t y t o t h e p r e s e n c e o f e l e c t r o l y t e s (Chambers, 1 9 5 9 ) .

S e p i o l i t e h a s a mud y i e l d of more t h a n 150 b b l s /

t o n . i n s a t u r a t e d s a l t water ( T o l s a T e c h n i c a l Data S h e e t , 10-81).

The u s e of

a d d i t i v e s such as magnesium o x i d e , copolymers of m a l e i c a n h y d r i d e w i t h e t h y l e n e improve t h e water r e t e n t i o n p r o p e r t i e s of s e p i o l i t e .

284

REFERENCES Alvarez Berengue?, A. and Perez Castells, R,, 1 9 8 3 . Sepiolite in the field of animal nutrition. Fifth "Industrial Minerals", International Congress, pp. 37-45. Alvarez Estrada, D. and Espinosa de lss Monteros, J., 1 9 6 9 . Agroquimica y Technologia de 10s Alimentos, Vol. 9 , No. 4 , pp. 5 0 2 . Alvarez Estrada, D. and Espinosa de 10s Monteros, J., 1 9 7 0 . Agroquimica y Technologia de 10s Alimentos, Vol. 1 0 , No. 1 , pp. 1 4 3 . Artho, A., Bonnet, J . , Koch, R. and Plantefeve., 1 9 7 2 . Retention of cigarette smoke components and influence of tobacco type and filtering material. Corresta Smoke Study Group Meeting, Williamsburg, October 2 7 , 1 9 7 2 . Barrer, B.M. and Mackenzie, N., 1 9 5 4 . Sorption by attapulgite I. Availability of intracrystalline channels'. J . Phys. Chem., 5 8 : 5 6 0 - 5 6 7 . Barrer, R.M., Mackenzie, N. and Macleod, D.M., 1 9 5 4 . Sorption by attapulgite 11. Selectivity shown by attapulgite, sepiolite and montmorillonite for n-paraffins. J. Phys. Chem., 5 8 : 5 6 8 - 5 7 2 Bourne and Holmes, 1 9 6 3 . Bel. Pat. 621204. Brauner, K. and Preisinger, A., 1 9 5 6 . Struktur und Entstehung des Sepioliths. Tschermarks Min. Petr. Mitt.,! 6 : 1 2 0 - 1 4 0 . Caillere, S. and Henin, S . , 1 9 5 7 . Sepiolite and palygorskite minerals. In: K.C. Mackenzie (Editor). The Differential Thermal Investigation of Clays, Mineralogical SOC. London, pp. 231-247. Caillere, S . , 1 9 3 6 . Thermal studies. Bull. SOC. Franc. Miner., 5 9 : 3 5 3 - 3 7 4 . Caillere, S . , Henin, S. and Meriaux, S . , 1 9 4 8 . "Xylotile" C.R. Hebd. S. Acad. Sci., Paris, 2 2 7 : 8 5 5 - 8 5 6 . Caillere, S. and Henin, S . , 1 9 6 1 . Sepiolite. In: G . Brown (Editor), The X-Ray Identifications and Crystal Structure of Clay Minerals, Mineralogical SOC. London, pp. 325-342. Caillere, S . , Henin, S. and Rautureau, M., 1 9 8 2 . Mineralogie des Argiles. 2. ClassiIication et Nomenclature Masson, Paris, 189 pp. Carrothersm Lawrence, 1 9 6 5 . Bel. Pat. 6 5 9 6 7 9 . Chambers, C.P.C., 1 9 5 9 . Some industrial applications of the clay mineral sepiolite. Silicates Inds., April, pp. 181-189. Cronsted, A., 1758. In: J.D. Dana (Editor), A System of Mineralogy, 6th edition, 1 9 8 2 , John Wiley and Sons, N.U. 696 pp. Dandy, A.J., 1 9 6 7 . The bleaching of cottonseed oil by sepiolite. East African Agricultural and Forestry Journal, 3 2 : 2 5 6 - 2 6 4 . Dandy, A.J., 1 9 6 8 . Sorption of vapors by sepiolite. J. Phys. Chem., 7 2 : 3 3 4 - 3 3 9 . Dandy, A.J., 1 9 7 1 . Zeolitic water content and adsorption capacity for ammonia of microporous sepiolite. J. Chem. SOC. A, 2383-2387. Dandy, A.J. and Nadiye-Tabbiruka, M.S., 1 9 7 5 . The effect of heating in vacuo on the microporosity of sepiolite. Clays and Clay Minerals, 7 3 : 4 2 8 - 4 3 0 . Dandy, A.J., 1 9 8 2 . Surface properties of sepiolite from Amboseli, Tanzania and its catalytic activity for ethanol decomposition. Clays and Clay Minerals, 3 0 : 3 4 7 - 3 5 2 . Fenoll, P . and Martin Vivaldi, J.L., 1 9 6 8 . Contribucion a1 estudio de la Sepiolita. IV. Superficie especifica de 10s cristales. Anales de Quimica 6 4 : 7 7 - 8 2 . Fernandez Alvarez, T., 1 9 7 0 . Superficie especifica y estructura de poro de la Sepiolita calentada a diferentes temperaturas. Proc. Reunion HispanoBelga Min. Arcillas. C.S.T.C. Madrid, pp. 202-209. Fernandez Alvarez, T. 1 9 7 0 . Variacion de la superficie especifica precalentada a diferentes temperaturas. Bol. SOC. Esp. Ceram. 9 : 3 7 7 - 3 9 4 . Fernandez Alvarez, T., 1972. Activacion de la Sepiolita con acido clorhidrico. Bol. SOC. Esp. Ceram. Vidr., 1 1 : 3 6 5 - 3 7 4 . Fernandez Alvarez, T., 1 9 7 8 . Efecto de deshidratacion sobre las propiedades adsorbentes de la palygorskita y Sepiolita. Clay Minerals 1 3 : 3 2 5 - 3 3 5 . Fernandex Hernandez, M.N. and Ruiz-Hitzky, E., 1 9 7 9 . Interaccion de isocianatos con Sepiolita. Clay Minerals, 1 4 : 2 9 5 .

285

Fersman, A.G., 1913. Research on magnesium silicates. Zap. Imp. Akad. Nauk., 32 : 32 1-430. Fleury-Larsenneau, A. and Andre, M., 1942. Etude du Pouvoir de Savon Charges. Chin. et Ind., 47:333-350. Galan, E., 1979. The fibrous clay minerals in Spain. Eighth Conference on Clay Mineralogy and Petrology, pp. 239-249. Grim, R.E., 1968. Clay Mineralogy, McGraw-Hill, N.U. 596 pp. Glocker, E.F., 1847. Synopsis, Halle, p. 190. In: A System o€ Mineralogy by J.D. Dana, 5th Edition, 1968, Trffbner and Co., London, p. 456. Globe and Fletcher, 1964. Fr. Demande 1385174. Gonzalez Hernandez, L., Ibarra Rueda, L. and Roy0 Mzrtinez. J., 1977. Sepiolita Nueva Carga Inorganica de Procedencia Nactional para Mezclas de Caucho. I Congress0 de Quimica del Automovil. Barcelona, 1977. Greenland, D.J. and Quirk, J.P., 1964. Determination of the total specific surface areas of soils by adsorption of Cetyl pyridinium bromide. J . Soil Sci., 15:178-191. HaUy, R.J., 1801. Traite de Mineralogie. Paris, Vol. 4, p. 443. Howman, 1964, Belg. ?at. 634702. Ioka, 1977a. J?N Kokai Tokkio Sho 54-37105. Ioka, 1977b. JPN Kokai Tokkio Sho 52-92891. Jimenez Lopez, A., Lopez Gonzalez, J.D., Ramirez-Saenz, A., Rodriguez-Reinoso, F., Valenzuela-Calahorro, C. and Zurita-Herrera, L., 1978. Evolution of surface area in a sepiolite as a function of acid and heat treatments. Clay Minerals. 13: 375-386. Kirwan, R., 1794. Elements of Yineralogy and Edition. Elmsly, London, Vol. 1, pp. 144-145. Kitayama and Wada, 1980. JPN Icokai Tokkio Sho 57-102822. Kitayama and Wada, 1981. JPN Kokai Tokbio Sho 57-169429. Longchambon, H., 1937. X-ray diagram. C.R. Acad. Sci. Paris, 204:55-58. Lopez Gonzalez, A., Ramirez-Saenz, F., Rodriguez Reinoso, C., Valenzuela Calahorro, and L. Zurita Herrera, 1981. Activation de una sepiolita con disoluciones diluidas de NO H y posteriores tratamientos termicos: 3 1 . Estudio d e la superficie especifica. Clay Minerals, 16:103-113. Lovell, M.J. and Rand, B., 1983. The rheological behaviour of sepiolite suspensions. Report of the Department of Ceramics, Glasses and Polymers. The University of Sheffield, Sheffield, U.K. Martin Vivaldi, J.L., and Cano-Ruiz, J . , 1953. Contribucion a1 estudio de la Sepiolite. I. Caracterizaction y propiedades de Sepiolitas espanolas. Anal. Edaf. Fisiol. Veg., 12:827-855. Martin Vivaldi, J.L. and Cano-Ruiz, J., 1956. Contribution t o the study of sepiolite. 11. Some considerations regarding the mineralogical formulae. Clay Miner., 4:173-176. Martin Vivaldi, J.L., Can0 Ruiz, J . and Martin Vivaldi, V.. 1958. Paper presented at IX Reunion Bienal de la R . S . E . de Fisica y Quimica. Yartin Vivaldi, J.L., and Fenoll, P., 1970. Palygorskite and sepiolites (Hormites). Ch. 2 0 . In: R.C. Mackenzie (Editor), Differential Thermal Analysis, Academic Press Inc., London, Vol. I.pp. 553-573. Martin Vivaldi, J.L. and Robertson, R.H.S., 1971. Palygorskite and sepiolite (The Hormites). In: J.A. Gard (Editor), Electron Optical Investigation of Clays. Mineralogical Society, London, pp. 255-276. Migeon, G., 1936. Contribution a l'etude de la definition des sepiolites. Bull. SOC. Fr. Min., 59:6-134. Michails, R. Sh., Braunauer, S. and Bodor, E.E., 1968. Investigations of a complete pore structure analysis. I. Analysis of micropores. J. Colloid Interface Sci., 26:45-53. Miyata and Sato, 1973. JPN Kokai Tokkio Sho 48-23266. Mffller, K.P. and Kolterman, M., 1965. Gas adsorption and structure of sepiolite Mg ( H 0 ) (OH)4 - [Si 0 1 H 0. Z. Anorg. Allgem. Chem., 341:36-40. 8 2 4 12 30 n 2 Nagata, M., Shimoda, S . and Sudo, T., 1974. Or dehydration of bound water of sepiolite. Clays and Clay Minerals, 22:285-293.

286

Nagy, B. and Bradley, W.F., 1955. The structural scheme of sepiolite. Am. Miner., 40: 8-85-892. Nederbragt, G.W., 1949. Adsorption of neutral molecules. Clay Min. Bull., 1 :72-75. Oguchi, Y., 1978. JPN Kokai Tokkio Sho 54-37105, Otsuka, R., Mariko, T. and Sakamoto, T., 1973. Mineralogische Eigenschaften von Meershaum von Eskisehir, Turkei. Memoirs of the School of Sciences and Engineering, Wasseda Univ., 37:43-52. Pierce, C., 1953. Computation of pore sizes from physical adsorption data. J. Phys. Chem., 57:149-152. Prado, F., 1864. Description Fisiografica y Geologica de la provincia de Madrid. Junta General de Estadistica. Impranta Nactional, Madrid, p. 148. Preisinger, A., 1959. X-Ray study of the structures of sepiolite. Clay and Clay Minerals, 6:61-67. Preisinger, A., 1963. Sepiolite and related compounds: its stability and application. Tenth National Conference on Clays and Clay Minerals, pp. 365-371. Prost, R., 1975. Etude de l’hydratation des argiles, interactions eaumineral et mecanisme de la retention de l’eau. These, Universite de Paris VI. Robertson, R.A.S., 1957. Sepiolite: a versatile raw material. Chem. Ind. (N.Y.), 1492-1495. Rodriguez Reinoso, F., Ramirez-Saenz, A., Lopez-Gonzalez, J.D., ValenzuelaCalhorro, C. and Zurita-Herrera, L . , 1981. Activation of a sepiolite with dilute solutions of HN03 and subsequent heat treatments. 111. Development of porosity. Clay Minerals 16:315-323. Rogers, L.E., Quirk, J.P. and Norrish, K., 1956. Aluminium sepiolite. J. Soil Sci., 7:177-183. Ruiz-Hitzky, E. and Fripiat, J.J., 1976. Organomineral derivatives obtained by reacting organochlorosilanes with the surface of silicates in organic solvents. These, Universite de Louvain. Ruiz-Hitzky, E., Casal, B. and Serratosa, J.M., 1983. Sorption of pyridine and palygorskite, Fifth Meeting of the European Clay Groups, Prague, 1983. Serna, C . and Fernandez-Alvarez, T., 1975. Adsorcion de hidrocarburos en Sepiolite. 11. Propiedades de superficie. An. Quim., 71:371-376. Serna, C., Ahlrichs, J . L . , and Serratosa, J.M., 1975. Folding in sepiolite crystals. Clays and Clay Minerals, 23:452-457. Serna, C. and Van Scoyoc, G.E., 1978. Infrared study of sepiolite and palygorskite surfaces. Proc. 1978 Int. Clay Conf. Oxford, Elsevier, p. 197-206. Serratosa, J.M., 1978. Surface properties of fibrous clay minerals (palygorskite and seuiolite). Proc. 1979 Int. Clay Conf., Oxofrd. Elsevier, pp. 99-109. Tolsa Research Report, 28-81. “Absorcion de NH por Sepiolita. 3 Tolsa Research Report, 32-81. Sepiolita en suspensiones fertilizantes 11. Tolsa Research Report, 11-82. Sepiolita en Plastisoles. Sepiolita como fluidificante. Tolsa Research Report, 14-81. Tolsa Research Report, 15-83. Arcillassen papel NCR 11. Tolsa Research Report, 22-82. Sepiolita en fonnulaciones cosmeticas. Tolsa Research Report, 23-82. CompartamienLo Reologico de suspensiones de Sepiolita I. Tolsa Research Report, 33-82. Poder Deodorante de la Sepiolita. Tolsa Research Report, 39-82. Sepiolita en formulaciones de antiacidos. Tolsa Research Report, 42-82. Sepiolita en Agricultura. Tolsa Research Report, 43-82. Sepiolita modificada como espesante de grasas I. Tolsa Research Report, 3-83. Eodificacion de sepiolita para formulaciones detergents. Tolsa Research Report, 9-83. Sepiolita como carga semirreforzante en Cauchos. Tolsa Research Report, 18-83. Sepiolita en Detergentes. Tolsa Research Report, 21-83. Absorcion de bacterias por sepiolita.

287 Obtencion de sepiolita organofilica I. Sepiolita en pinturas. Suspensiones de sepiolita como soporte de semillas pregerminadas. Tolsa Research Report, 34-83. Sepiolita en recubrimientos asfalticos. Tolsa Research Report, 41-83. Sepiolita en formulaciones cosmeticas 11. Tolsa Technical Data Sheet, 12-80. Sepiolita como decolorante de aceites. Tolsa Technical Data Sheet, 16-80. Sepiolita como sorporte de pesticidas. Tolsa Technical Data Sheet, 10-81. Sepiolita coloidal. Tolsa Technical Data Sheet, 16-82. Sepiolita en formulacion de Caucho Natural. Tolsa Technical Data Sheet, 23-82. Propiedades absorbentes de granulres de sepiolita. Tolsa Technical Data Sheet, 30-83. Gelcos-10 G. Weaver, C.E. and Pollard, L.L., 1973. The Chemistry of Clay Minerals. Elsevier. Amsterdam, 213 pp. Tolsa Research Report, 26-83. Tolsa Research Report, 29-83. Tolsa Research Report, 32-83.

This Page Intentionally Left Blank

2 89

APPENDIX I & I1

C o m p i l e d b y R.A.

Callen,

D e p a r t m e n t of Mines a n d E n e r g y ,

APPENDIX I

-

D e t a i l s of

land occurrences.

APPENDIX I1

1.1-3:

-

South A u s t r a l i a .

D e t a i l s of D e e p S e a D r i l l i n q P r o j e c t o c c u r r e n c e s ,

B,ibliography.

1.4:

290 APPENDIX I

-

1.1 PALYGORSKITE REFERENCES - OCEANS S t u d i e s on DSDP c o r e s i n order of s i t e number See appendix 11.1 f o r f u l l r e f e r e n c e .

-

Leg

Sites

Author

1

1&3

Gorbunova, Z.N.

2

701 5 8,9.12.

Gorbunova, Z.N. 1979 Kassovskaya, e t a 1 1975

9 10 12 128 12B,

Gorbunova, Z.N. 1972 Chamley, e t a 1 1977 C a l v e r t , S.E. 1971 Lomova, O.S. 1975 Rex, R.W. 1970

12C

1979

15-1 7 20 & 21

Gorbunova, Robert, C.

4

26, 29,

Chamley e t a 1 1977 Rex & Murray 1970

6

46-52

Gorbunova, Z.N.

1972

9

79

Chamley, e t a l .

1977

10

85-89, 92

11

98, 99A, 105 105 105-110

12

116-1 17

13

124, 125A, 125 125-1 34

14

131-138 135-1 38 135-142, 139-1 4 4

3

28 29B

102 104-106

Z e m m e l s , e t a 1 1972 Chamley, n. 1979 Chamley 6 Robert 1979 Hathaway L Schlee 1968 Gorbunova, Z.N.

157, 157A, 163A

17

164 164, 165A, 169-1 71

1979

Chamley, e t a 1 1978 Chamley, n. 1975 Z e m m e l s L Cook 1973 Chamley. H. 1975 HSU e t a 1 1973

132-134

Lomova, O.S. 1975 Berger & von Rad 1972 Gorbunova, Z.N. 1979 Pow-Foong & Rex 1972 von Rad & Rosch 1972

144

16

1979

1981

Cook L Zemmels 1973 Chamley e t a1 1977

93-97

100,

Z.N.

161,

161A,

166,

167,

163

Zemmels,

I. 1973

Couture, R.A. 1977 Z e m m e l s L Cook 1973

29 1

20

196 196,

C o u t u r e , R.A. 1977 Matti e t a 1 1973

198A

Matti, e t a1 1 9 7 4 C o o k , P . J . 1977 V a l l i e r L Kidd 1977

22

211-213, 211-218 211-218

23

21 9-224 219-230 219-230 219-230 21 1-223

24

23 1 238' 231-238

-

M a t t i e t a1 1972 V a l l i e r & K i d d 1977

25

239-245 2 39- 245

M a t t i e t a 1 1974 V a l l i e r L Kidd 1977

26

246-255 250-253,256 253-255

V a l l i e r L Kidd 1977 C o o k e t a 1 1972 C o o k , P . J . 1977

27

256-263 256-263 259-262

C o o k , P . J . 1977 V a l l i e r L Kidd 1977 C o o k e t a 1 1972

28

26 4 264 264,

Cook, P . J . 1977 V a l l i e r L Kidd 1977 C o o k e t a1 1975

215 L 216

266,

V a l l i e r & Kidd 1977 H e e z a n e t a1 1965 M a t t i e t a 1 1974 S t o f f e r s L Ross 1974 Weser 1974

272

29

282

C o o k e t a 1 1974

30

288A L 289

Z e m m e l s e t a 1 1975

31

302

C o o k e t a1 1973

32

305,

33

316 L 317A

C o o k & Z e m m e l s 1976

34L34A

319A

F l o o d 1978

35

323

Z e m m e l s L C o o k 1976

37

332-334

Zemmels,

38

343

W h i t e , S.M.

39

356 L 357

R o b e r t , C.

40

354-364

C h a m l e y L R o b e r t 1979

41

366-370

Melieres, F. 1978

42L42A

372, 374-376 374-376

Chamley,

44

390

C h a m l e y L R o b e r t 1979

310,

311 L 313

Zemmels L C o o k 1975

H a r r o l d L C o o k 1974 1976 1981

e t a 1 1978 Melieres e t a1 1978

29 2 395

47

398, 400 399-402 397 398

Chamley Cassat, Chamley Chamley

398

Latouche. C.

1979

48

403- 406

L a t o u c h e , C.

1979

50

415-416

Chamley e t a1 1980

51-53

417A, D, 418A, B

Mann

~

47A 47B

54

&

396

Timofeev, e t a1 1976

45

&

&

R o b e r t 1979 1979 & Giroud d'Argoud 1979 e t a1 1979 &

G.

M u l l e r 1977 e t a 1 1979

Skornyakova,

58

58

442, 444

Chamley, H. 1980

60

458, 459, 460

D e s p r a i r i e s , A. 1982

61

462

Kurnosov, V.B.

1982; N a t l a n d

&

&

Mahoney

Shevchenko, A.Y.

1982.

Others

Subj ects

Authors

M i d - A t l a n t i c Ridge

Hathaway, J . C .

A t l a n t i c d e e p sea s e d i m e n t s

B o n a t t i , E. & J o e n s u u , 0. 1968

1 1 b o r e s o f f coast of Morocco. N o r t h e r n I n d i a n Ocean.

Chamley, H. & M i l l o t , G. 1970; Goldberg, E.D. & G r i f f i n , J . W .

Miocene d i a t o m i t e , S a n t a Cruz Basin ( C a l i f o r n i a ) .

F l e i s c h e r , P.

Western I n d i a n Ocean.

Venkatarathnam K o l l a e t a 1 1976

Off A l g e r i a (Gulf of Arzew)

F r o g e t , C. & Chamley, H. 1977

Deep-sea P a c i f i c

Church, T.M.

&

Book on p a l y g o r s k i t e s of t h e world, e s p e c i a l l y Russia.

Lomova, O.S.

1979

O f f Algeria (Gulf of Arzew)

F r o g e t , C. 1980

K u w a i t Bay and Arabian Gulf ( G u l f of P e r s i a )

K h a l a f , F.T. e t a1 1982, S e i b o l d , E. e t a1 1973,

C a s p i a n Sea

T u r o v s k i i , D.S.

6 S a c h s , P.L.

1965

1972

Velde,

B.

1979

e t a1 1981.

1970

293

-

1.2 PALYGORSKITES TOTAL AND AVERAGE % I N DSDP CORES ( L e g s 1 - 5 8 ) A s recorded i n I n i t . Rep. Deep Sea D r i l l i n g P r o j .

HOl.

L.Plei. E.Plei. Plei. Qu Plio/Plei. L. P l i o . E-L. P l i o . E. P l i o . Plio. L. Mio. M-L. Mio. M. M i o .

.

E. M i O . Miocene L. M i o - P l e i . L. O l i g . M. O l i g . E. O l i g . Oligocene L. Eo. M. EO. E. Eo. Eocene L. P a l . - E . EO. L. P a l . E. P a l . Paleocene Maast. Camp-Mads t. Camp. Sant./Camp 1 Sant. ) Cont./Sant ) Con. )

nr

.

Cen. & Cen/Tur L a t e K. Alb. 1 Alb-Cen. Aptian-Alb ) Aptian 1 Bar-Aptian Early K Valang-Ti t h . Oxfordian L a t e Jurassic

11.8 25.1 21 .8 21.2 30.0 23.4 20.6 25.5 24.7 26.2 17.0 31.6 29.0 26.8 27.0 30 35.8 20.4

8.2 13.5 16.7 16.4 20.7 18.3 15.6. 18.2 17.6 19.3 11.4 22.2 21.7 19.6 17 23.4 18.0 24.4

46.5 25.8 51.4

31 .O 15.8 26.9

32.1 23.2 31.5

9.6 9.50 14.8

27.5 22.6 39.9 25.8

18.7 19.1 16.7 11.8

17

36.3

22.8

104 447

2 20

22.3

24.0

343 43) 175

8 28 1 6

42.9 40.8) 29.2

23.8 (12.9)* 14.7

9

2

32 60 247

2 2 7

200 326 2828 3289 720 2879 642 1300 5183 2068 289 885 755 4202 2210 120 1648 265 21 23 791 748 874 261 0 28 9 441 189 1110 49 5 181 2075 129

17 13 130 155 24 123 21 51 210 79 17 28 26 157 82 4 46 13 68 17 29 17 67 9 19 6 44 18 8 52 5

61 7

2 holes only

N e a r l y all 1 h o l e

Mostly 2 h o l e s

M o s t l y 1 hole

50% from 1 hole

E s t i m a t e d from summary log r e s u l t s ; i n d i v i d u a l samples n o t l i s t e d .

29 4 Data from "unoriented" samples

5 16 3 12 30

Miocene-Pliocene Miocene E. Miocene Oligocene L. Eocene M.

M.

M. Eocene M-E. Eocene

E. Eocene L. P a l - E. Eocene E. Paleocene Maastrichtian Camp-Maas t. Campanian Coniacean/Sant. Turonian Cenomanian-Alb. & Albian Aptian-Alb. L Aptian Bar. - Aptian

,'

95 1 46

75 7 1

1

5 1 3 3 13 1 10 1 1 1

1 1

1 2 4 6 58

1 2 6

79

7

7

1

295

1 . 3 PALYGORSKITE IN DSDP CORES m , % t o n e a r e s t whole number.

Site

12

12B

%

Depth

a5 97 104 114 162 113 119 161 161 162 162 215 215 215 215

Present I

Eoc. L. Eoc

L.Plei.

257-264 500-505 551-553

19 14 24

L.Plio. L.Pal E.Pal

a7

649-650

12

M.Mio.

88

51-59 99-104 104-1 oa 128-136

a ia

E. P l e i .

a9

93 94

95

396 400 416-425

23 24 9

E.

425 434

22 26

E. Sant.

94-98 135-138

24 10

Olig. Eoc.

167-175 207-211 217-218 223-224 232-234 240-241 273-275 312 34 9

10 14 11 7 16 9 56 24 31

I,

9 9A

0.4-7 15-21

12 9

Plio/Plei.

100

204-210

17

Val angTith.

206 241 248 259 2 60 262 267 268 277 277-279 287-291 312-313

15 24 3 4 41 63

94 I, 91 P73,S5 24 4 ~ 3 8 , s ~ s4 pza,s3i 2 5 3 3 12 3

86

Age

98

19-28 48-52 99-108 189-190 210-212 292

a5

10 17

,I

#

11

Depths t o n e a r e s t

%

Site

P1 i o . ,I

70

OATA BASE, < 2 u , o r i e n t e d .

Age

4

ao

-

..

L.P1 i o . I,

E.P1 i o .

Depth

Camp.

L. San t I

Pal. ((

Sant-Camp. I,

0

L.Jur.

48

64 9 19 33 27

Oxf. It

Oxf-Call

0-3 51 220-22a?

9 5 20

L.Plei. M.Plei. E.Plio.

102

512-513

60

E.Plio.

0 1

13 19

L.Plei.

104

M.Mio.

11 10 62 75

L.Eoc. M. Eoc.

10 8 30

417-418 499-500 503-504 572

306-312 402 616

332-340 363-364 378-379 391

38 16 13 26

,I

I,

I

I1

106

340-343

10

E.Plei.

E.Eoc.

125

2-6 19 24 27 29-34 39

27 33 49 41 40 44

Plei.

M.Eoc. L. Pal E.Pal. ,I

.

.

E.Plei. I,

L.P1 i o .

.

296 I,

139 40 46 47 52 53 60-62 60-62 67 79 89

51 55 39 18 60 37 64 36 49 41 14

36-43 76 78-79 105

16 18 14 6

Plei E. P1e i

127

21 435

9 47

L.Plei. E.Plio.

129A,B

39 40 40 80 94

41 65 8 40 5

? M.Mio.

126

130

131

132

I, I,

,# II 0,

I,

E. P1i o . L.Mio. 0,

I

..

,a

135

L.L.Mio. L.M.L.L.Mi 0.

95 0 15 16 18 50 53 53 78 79 80 150 411 413-417

16 12 29 16 9 36 20 8 6 20 33 11 78

33 49 49 208 210 264

8 26 10 13 6 16

Quat.

0.15 2 15 19 29

16 6 21 9 12 10 17 8 9 10 11

L.Plei.

136

,I

137

I1

Plei. II I,

II I,

L.Plio. ,I I1 II

l8 22 19 16 16 26 33 22 30 19

249 289 318-321

15 12 9

261 336 433

35 14 9 6

7 29

: E.Plio. I, 1

,I I, ,I

L.L.Mio.

,, ,I II

I,

L.Plio. E.P1 i o . 1,

12 M.Mio. 65P,14S E.Eoc. L.Camp-. 38 E. Maa s t .

I,

33

74-80 82- 86 96 100-107

134

110 118-121 127-135 155-162 165 166 174 176 176 181 182 183 208 209 215 223

434 565 565 565 565 686

14 12 34 36 41 27

131-138 217-224 237-240 245-248

23 28 20 54

254 263

52 24

263 281 289

9 98 32

53-57 59 100 136 137 139-143 166 167 167 218

19 13 97 61 46 60 40 29 32 39

219 265 274 284 285-287

36 6 4 8 6

I,

Cret. 1

11

Apt ian E.Plio. E-M.Mio. E.Mio. L. 01 i g . E. Mio. ? ConnSant 1

.

E.Cen. I,

Tert. II

Tert/Cret. ,I II II

Maast. #I

11

?Turon/Ca

?L. 11 Cen. ,I

,I

297

12 5 12 5 6 9 7

302 303 303 306 343 349 377 138

111 111 112-115 117 118 184 333 428 429 429 429

139

140&140A

141

:

2 19 11 6 8 96 19 24 15 17 3

142

529 531 576-579 164

15 11 5 6

214

14

215 215 216 217 296

23 35 12 26 20

324

15

327

20

12 24 24 28

19 14 14 17

Holo. L.Plei.

158

143 289

16 21

L.Mio. M.Mio.

159

6 10 2 3 4 7 7 9 43 44 49 53 54 55 56 57 57 58 59 60 61 62 62 64 64 66 67 68 69 70 72 73 74 80 83

16

Quat L.Mio. E.Mio.

144 E.Cen. L. A1 b i anE.Cen. E.Olig. I,

I

? Camp. Cen. 157&157A Cam.

115 228 230 3 54

7 12 27 9

M.Plio. E.P1 i o .

?

151 237 239 240 243 313 369

14 15 7 17 14 32 56 61

L. P1 i o . M-L.Mio. M.Eoc.

432 513 588

90 80 4

648

15

6,

M-L.Mi

L.CampE. Maa st. L.Cen-. E.Tur. I, 0

L.AptE.Cen. L.AptAlb.

,,

I, I,

M.Mio.

I,

8

M or E.Eoc. ?Pal /Eoc. L. C r e t ?E. Pal. Maast.

7-13 15-22 24-31 34-41 42-49 51 51 51 60-67 80

16 23 14 24 24 P29,S6 P 3 2, S 11 P40,S27 22 29

E.Plei. L.Plio.

82 86 102 192 193 197 287

33 36 P65,S14 75 19 24 31


L.E.Plio. M-E. P1 i o . I'

" " 0

EL.M.Pl i o . ,I I'

? ? ? ?

161

I1 21 11 19 33 14 17 16 14 31 48 42 46 28 44 32 48 51 40 58 54 54 45 61 39 28 51 25 30 30 25 54 41 49

0.

I

.

L.0lig. ,I

298

163&163A 162 174 177 180 184 187 188 190 193 197 199 202 204 210 212 216 221 225 228 231 237 240 2 42 264 271

164

165A

166

85-89 91 113-114 116 118 150 159 160 170 179 188 207 216 253

31 48 42 46 28 44 32 48 51 40 58 54 54 45 61 39 28 51 25 30 30 25 55 41 49

38 24 59 65 60 67 60 59 54 20 60 58 67 18

E. Maas t I, I,

I,

11

230 253

63 32

I1

167

697 808

8 40

M.Maast. E.Camp.

169

108 193 193

27 47 57

Camp. Tur.

7

12

108 113

57 39

L.01 igE.Mio. M-E. Camp.

2 27 28 30 33) same 33)sampl e 35 35 35 36 46 49 52 55 57 59 59 63 66 68 68 68 69 70 77 77 89 89 105 113 113 113 121 122 130 226

12 38 24 18 27 57 39 59 65 60 69 60 54 20 60 57 57 60 67 57 70 66 19 63 18 32 20 9 33 13 17 16 29 6 13 18

Plei M.Mio.

104 105 107 108 108

44 62 49 30 14

Camp.

93

25 35

L.Cret.

.

L. Camp. I1 I,

,, ,I I,

170

,I I, I1 I,

171

I I I, ,I

I1 I, I,

E-L.Camp. boundary Camp. ? Con.Sant. I,

11 I, I I

Cen ./Tur. 0,

? ? ?

30 291

18 20

L.0lig. L.CampE.Maast.

2 92 344 371 371 3 72 397 399 427

9 33 13 17 16 29 6 13

,I

222

57

224 225

70 65

L.Camp. Camp. $1 ,I

L.Cret. 4

196

? L.AlbCen. I

I

198A

II

I1

.

I 41

,I dl I

8

E.Mio. I I, I,

? ? ? ? L.0lig. I, ,I

I,

1,

E.Olig.

,, I1 ,I 4

,a

M.Eoc. E Maa s t .

.

,I

,I 1

,I

11

299

200/201?

211

97 110

42 20

117 122 123 125

42 42 60 10

E.Camp.

29 29 30 32 32 33 33 33 34 36 37 38 38

25 35 42 44 62 49 30 12 20 42 42 60 10

L.Mio.

398 409

15 64

? L. Camp-. E .Maa st. E-M.Camp.

419 420 428 212

213

215

216

219

31 59 63

Camp. I

220

28 102

14 32

E.Plio. L.0lig.

221 222

149 23 23 24 26 30 36 37 38 45 52 53 88 89 95 97 103 105 121 125 126 128 128 131 147 148 148 149 152 155

25 44 88 86 6 13 11 31 30 57 28 6 18 92 56 22 33 22 15 38

Mio/Plio. Plei

I,

,,

I

I ,I

8,

I,

173 289 320 412 483 484 484 489 497 507 5 08

6 18 22 7 7 21 20 38 52 52 53

E. -M.Mi 0.

84 100

6 13

L.Mio ?E. EOCM.Mio. ?M. M i 0. E.Eoc. L.Pal.

? L-M. EOC. ? L.Cret. 223

? ? ? ?

117 125 145

11 30 57

74 76 77

44 88 88

E.Eoc.

121 293 311 346

31 92 56 22

M.Mio. Pal.

69 135

14 37

L.Mio. E.Mio.

I,

L. Maa s t . 224

6,

I,

I1 0,

II

I

,I

L.Plio. I, ,I

8

7

I

31 47 63

I,

7

t

21 20 38 48 53

364 39 40 367 ) 367 ) 48 367 ) 0.5m 40 367 ) 367 ) 40 367 ) 31 3 70 46 370 27 371 25 386 44 413 11 488 47 488 65 489 65 496 24 497 17 525 12 7 593 611 17 96 699 7 56 783

.

I8

40 18 8 4

,I

,I ,I 6,

E.Plei. L.Mio. 43

,, 8 I I,

0

M.Mio. E.Mio. I, I,

L.Olig. I1

M.O1 i g . M.Eoc. L.Mio. E.O1 i g . M-L. EOC. M.Eoc.

300

785 786 225

12 23

I1

22 26 27 40 58 66 85 88 90 91 96 115 162

22 29 40 17 29 18 35 40 33 37 4 22 13

28 48 92 116 134 142 162

50 14 8 30 10 18 8

37 161 222 278

14 15 16 6

?

229A

22

22

?Quat.

230

4

10

?Quat.

231

3 19 278 397 566

41 43 39 52 64

Plei.

219 242 284

44 40 29

1 1 1 7 7 8 8 9 9 10 11 12 15 15 16 18

53 10 8 22 22 22 40 50 14 39 14 17 14 14 28 29

227

228

232A

232

20 21 26 27 28 28 28 29 29 31 31 35 35 41 41 43 49 49 49 50 70 85 107 112 112 112 112 112 112 113 113 113 118 126 126 149 149 149 151 151 158 160 181 186 213 230 239 239 240 301

E.Eoc. L.Plei. E.Plei. I

,I

L.Plio. II

0,

,I

I1

’

E.P1 io. I,

L.Pl i o . 8

E.Plio. I,

II ,I

L.Plei. L.P1 i o . ,I

I,

L.Mio. ,I

M.Mio. E.Pl io. I, L.Mio.

234

18 14 35 40 8 34 37 4 40 32 13 22 30 37 10 18 5 13 5 3 16 6 50 40 48 43 39 40 31 46 27 25 44 11 47 47 65 65 24 17 60 12 7 17 18 8 4 12 23 6

2

33

5 85 241

29 24 9

L.Plio. I,

P1 io-. L.Mio. ,I

E.Mio. L.01 ig.

or

earlier 235

2

28

P1 e i

.

301

30 38 23 41 35 44 52 16 29 53 18

32 70 75 75 75 75 93 221 269 269 270

,I

27 16

Plei. L.P1 i o .

159 163 2 18 264 303

6 13 10 41 43

? ? L.0lig. L.Eoc. E.Pal.

4 74 76 80 161

16 15 15 14 15

Quat. ?Plio. P1 i o .

240A

169

12

L.Mio.

242

0

78 33 28 41 29 63 43 I9 30 15 21 26 15 74 23 35 52 15 24 70 50 12 5

Plei.

238 239

240

5 56

1 1 1 2 3 6 I

10 13 14 21 21 21 23 23 23 24 26 29 33 33 34

,'

8 166 321 27 59 78 97 102

19 63 33 6 20 39 57 62

? E.Eoc. L.Pal. ? L.Eoc.

258 259 286 289 303 3 04

37 46 61 12 22 8

L. Camp.

58 646 664 684 702 713 720

7 17 23 5 30 29

? ? ? Con. ? ?

251A

453

40

L.Mio.

2 52

1

18

?L .Mi 0Plei.

,

Plei. P1 i o .

18 19 38 39 44 77 109

0.

,I

18 18 19 13 20 18 14

236

9 18 61 22 60 20 62 44 4 9 40 21 29 29 18 39 29 9 52 36 20 64 19 15 9 11 14 9 10 26 45

,I

P1 i o / M i L.Mio.

I, I,

L. Mio. 8,

Mio.

245

I

I,

249 P1 i o / P l e i I, 4,

I, I, 0,

250A

I0

8, I,

I1 I, I,

I I,

,I

4

41 41 44 45 48 52 56 67 67 73 74 81 82 82 82 85 86 93 121 137 151 173 237 311 410 480 559 602 609 654 675

L. P1 i o .

33

I

,a I0

L.Plio. E/L.P1 i o . ,I I,

I

I,

I,

E.Plio. L.Mio. I

a

M.Mio. E.Mio. L.01 i g . M.Olig. 8,

L.L. Eoc. ?E.L.Eoc.

M/L. Eoc M.Eoc.

.

11

?

E.Cret. @at.

.

302

1 1 2 3 3 5 8 15 16 18 22 23 23 24 24 29 31 33 37 42 44 46 49 49 50 51 51 65 67 72 79 79 80 87 88 90 91 92 92 93 95 96 98 98 110 111 111 116 120 122 124 125 127 146 148 162 170 177 178 179

16 16 14 19 21 54 6 29 28 33 23 15 15 39 10 57 62 34 24 36 33 20 6 15 13 63 6 15 10 19 37 46 41 61 12 12 19 43 22 18 15 28 33 23 54 59 54 21 55 87 38 9 39 11 27 25 14 12 21 20

184 186 191 199 206 229 255

9 10 35 26 45 22 23

1 9 12 17 21 24 27 28 29 30 33 35 38 41 44 47 53 56 59 61 62 94 111

44 23 14 16 40 19 10 12 13 15 11 7 18 12 11 11 50 23 32 29 11 7 21

32 47 49 50 52

6 12 10 14 41

E.Mio.

458 53 5 536 579 610

9 36 12 25 68

64 9 7 62 762 7 62

79 15 8 10

E.Olig. L. Pal E.Pal. M.Maast. ?E.M. Maast Camp.

289

1138 1194 1231 1232 1234 1260

355 43 77 74 37 55

3 02

140 163 163 177

9 36 12 25

,I 6, ,I ,I

I,

II

272

,I

It

I, I,

I,

I I ,I

I1

00 ,I

I1

I1 II

282

00

I,

,I ,I

,,

288A

I,

I1 1,

,I I,

,I

, I

,I

? E.P1 i o .

L.Mio. I, ,I

I 1,

M-L .Mio. 0,

I,

I

a I, I, 0,

00

.

.

Con. I

I,

I

I

I, I1

I, I,

,I ,I

E.Pal. E Maas t . L.Camp. Apt-Camp. Apt.

.

L.Mio. ,I 0,

,I

303

186 198 232)same 232)Sample 232 262 347 364 375 375 376 3 84

68 79 15 8 10 8 355 43 77 74 37 55

50 51 52

7 7 46

M.Mio.

57 61 67 80 89 94 137 142 145 156 184

14 7 13 24 11 20 17 5 6 16 14

L.01 i g .

212 552

15 5

608 618

4 15

69 79 89

20

118

11

334

21

31 1

13

7

313

235

21

305

310

31 8

7 7 46 14 7 13 31 20 8 11 20 11 17 5 6 16 14 15 21 8 21 11 5 4 15

69 71 79 88 98 101 103 104

1

1 9 5 7 14 19 26

332B

141

1

333

0 0 0 18 19 25 79 154 157 160 169 172 173 174 178 184 186 189 203 205 214

7 4s 5 7 3 7 6 21 21 25 1 1 1 10 67 2 2 4 2 69 70

334

134

4

I,

L.OligE.Mio. I( I

L. Eoc. M.Eoc. E. Eoc. L .Maast. I,

M-Maast. L. CampE.Maast. L.Camp. E.Apt-. Barr.

332A

I,

Apt-Haut. L.Mio. M.Mio. M.Mio-. E.Olig. E.Camp-. E.Maast. E .Camp-. L.A1 b. P l i o or younger EM. Maast

306 400

8 11

515 515

? ?

L.Pal.

317A

585

?

M.Camp.

323

4

7

L.P1 i o .

316

15 16 16 17 19 20 21 24 27)same 27)sample 29 36 42 43 44 47 56 65 72 93 102 122 168 185 188

. .

.

E.Maast. L. Camp-. E .Ma a st. I1

Plei. L. P1 i o . ,I

I, I, I,

?L.P1 i o .

L.Mio.

304

335

343

366

367

368

138 149 183 237 243

2 2 10 3 7

89 91 92 132 221

1 2 2 9 4

2 7 8 10 11 16

8 11 5 3 6 11

596 616 649 658 683 693 702

1 4 2 1 1 1 1

306 306 351 351 372 373 392

8P, 18s lP,lS 10P,4S 17P, 3s 13P 17P,llS 36P,39S

620 638 6 50

7P 4P 2P

274 279 289

1 4P,lS 28P, 3s

315 326 330 371 386

30P, 3s 63 69 20 27

395 408 431 441 468 517 538

42 59 63 66P ,4S 43P. 5s 52P; 10s 33~,34S

564 5 73 585

52P 32s 55PY35S 7P, 3s

,I I 40

,I I,

L.Plio. a I,

5 93 602 612 620 630

47P,37S 27P,8S 29P ,6S 33P, 85 28P,18S

640 651 727

l l P y 1 6 S 'I 6P, 7s " 2 L.Cret?Pal.

E.Plio. 0,

Plei I,

.

,I

,

369

0,

I,

M.-E.EOC.

E.Eoc. I'

,I I1 I,

L.Eoc. I,

M.Eoc. I,

E.Eoc. ,I

L.Pal-. E.Eoc. L. Cret E.Tur.

.

I,

E.Mio. I,

?M.EOc-. E.Mio. I1 ,I I,

?M.Eoc. L.E.LM Eoc. E.Eoc. I, I, I, ,I

'I

L.Pal-. E.Eoc. "

'I

370

" 'I

" 'I

L.Cret-. L. Pal

.

727 7 54 803 84 1

7

I,

6 7 5

L.Cret.

84 102 102 350 357 378 398

1 2 2 2 1 1 1

406 418 424 435 447 453

2 4 2 23 2 2

463 473 483

14 3 14

105

5

2 08

209 220 325 325 428 466 484 485? 5 04 541 551 552 552 569 592 608 618 655 675

10 1 3 3 3 6 2 8 5 6 7 2 l P , 1s 1 16 11 29P,7S 8P,lS 5P,2S 6

684 696 753

12 13 9

I

Camp-Con. M.Mio. ,I

L.Eoc. M.Eoc. Maast. L Camp-. E. Maast Camp. Con-Sant Alb. A1 b.

.

L. Apt-. E.Alb. II It ,I

M.Mi 0 - . P1 i o . M.Mio. I,

E.Mio. 01 i g . 0,

II

M. Eoc. ,I I,

,I 4,

II

I,

I, I,

E.Eoc. "

E.Pal. L.A1 b-. E.Cen. I, I

?Alb.

. .

305

29

2 9B

241

L. Apt

771

28

810 828 838

10 8 7

877 884

5 5

138 139 193 195 198 200 202 203 20 7 210

23s 25s 42s 40s 36s 34s 34s 24s 25s 31s

M.Eoc.

219 220 221

23s 28s 32s

M.Eoc.

10 18 48 59 72 137 145 151 212 237 296 297 31 1 323 380 410 480

7 4 6 5 5 36 5 20 6 19 9 13 15 10 22 9 11

Quat.

484 531 559

4 25 14

581 5 85 602

19 17 9

609 627 654 675 750 837 978

10 7 26 45 12 10 4

979 980

6 8

E.Alb.

.-

,I I,

Barr-. E.Apt. Barr.

248

" "

981 982 983 1068 1070 1071 1169 1170 1170

8 5 6 5 9 15 26 10 14

4 121 315

16 24 43

361 363 363 393 399 408

54 59 54 55 87 50

416

39

Depth (in) 620-725

Tr,P

" " " " " "

"

Tur. M.Cen. ,I

? ?

.

Plei L.Plio. L. E. EOC-. E.Mio. L.E. Eoc. ,I

E.Eoc. Pal o r E. Eoc.

"

398

E.Plei.

680-725 725-730

L.Plio. I

730-750

L.Mio.

.Pal.

M.Mio.

770 780-810

I, I,

1000-1045 E. -M.Mi 0.

E.Mio. ?M.Eoc-. ?L.O1 i g . E. -M. EoC. E.Eoc. ?Pal ?E.Eoc. ?Pal.

-.

8

?CampPal. I

Con-Camp.

,

6,

I, ,I

M.CenTur. I,

1065-1190

Tr,S. Ave.l5%P, 15%S-(up t o 25%) S only,@

"

25X, Ave. 15% S only. " P only, L.Maast. 0-15% -E.Pal P 0-15% L.L.Alb.L.M. Alb. P 0-30% " Ave, 10%.

459

Approx. 549111 5-17%P.

460

Approx.57m

462

L.Pa1.E.Eoc.

?M.Eocene

60-75%P. L.Eocene 15- 20% Cen. t o i n (2 p E. Sant. fraction

1.4 PALYGORSKITES: LAND DEPOSITS ( M o s t l y sedimentary d e p o s i t s

-

w

v e i n s and most s o i l s excluded)

L o c a t i o n , Basin and Reference Number

Age

Associated Rocks

Parana Basin, B r a z i l 65

E. Pal eocene (Dani an)

Mg-limestone, f i n e sandstone, basalt

Freshwater, lacustrine

Yucatan P e n i n s u l a 5, 38

E. Eocene

Dolomite, caliche, c l a y 1 imestone

Marine 1agoon

Cuba 19

Cretaceous

Serpentinite, sapon it e , christobal i t e , talc.

?hydrothermal

Pure v e i n s

S

Negev, I s r a e l

E-L. Pal eocene

Marl, chalk, f l i n t , phosphate ( i n overlying rocks) z e o l i t e , opal, b a r i t e , c e l e s t i t e , gypsum

Marine

20-40%, 60-80% i n c l a y fraction

P,S

1

Environment

Concentration and e x t e n t

0 p.

Disseminated i n sandstone, r a r e l y pure ?180 000 km2

P/S

P,S

P

P

Jordon Valley, I s r a e l 75

E-M.Eocene

C e n t r a l Turkey

01 igoceneL.Miocene

Gypsum? l i m e s t o n e c e l e s t 1t e

Marine

9600 km2

4, Dl6 S y r i a . 80

P1 iocene

Clayey and sandy

Lacustrine

?

p,

S y r i a (NE). 80.

U. Miocene

C1 ayey and sandy

L a c u s t r i ne

?

P

Marine

Weathering from T e r t i a r y rocks

South A r a b i a ( c e n t r a l ) l C , D11

Te r t ia r y

Saudi A r a b i a 73

MioceneP1 iocene

L ime s t one gravel

?a1 1u v i a1

Extensive 6-30s

P

Nevada-Texas High P l a i n , Death V a l l e y U.S.A. 37, 39A, 43A, 248, 07, DlOC

P1 iocenePleistocene

C a l i c h e cap, i n a l l u v i u m and s o i l s on these rocks. Do1omi t e chert, volcanic ash.

Lac u s t r ine and s o i l s

Some pure sepiolit'e i n playas

P,S

South C a r o l i n a , Georgia, F l o r i d a , Georgia S h e l f U.S.A. 58, 74A

L. 01 igocene t o E.M. Miocene

Clay, l i m e s t o n e protodolomite

Transgressive brackish ; t i d a l lagoon.

1-5 m puse, 3-4000km

P,S

Green R i v e r , U.S.A. 67 9

E.-M.Eocene

O i l shale, d o l o Alkaline m i t e , marl, c l a y , lake Na- r i c h e v a p o r i t e s .

10,000 km2

S

Central Portugal, around L i s b o n 10,

Pal aeogene probably Eocene

M a r l , c l a y sand congl omerate, limestone, dolomite, s i l i c i fied. Basalt.

?Marine

E.Galice, 30

Miocene 01 igocene

Marl, l i g n i t e

?Marine

Spain

L e b r i j a , Spain 18

U.

Caceres, Spain 16A

Miocene

Pliocene

P

500 km2

s,p

5-10% Limestone, c l a y , Chert ( w i t h S)

Brackish lacustrine

P:0.3-3m o f 35-37% P,S S:15m. 100%

Marl, dolomite

Lacustrine

2-5.5111, 80% 200km' P,S b4

0 U

-

Zomora, Spain 7 2A

Te rt ia r y Quat e r na ry

Oeuro, Spain

See Legeuy e t al.,

Aqu it a i ne ( L o i r e A t l a n t i c a ) France 27, 59

M.Eocene t o L. 01 igocene

Cambon & S a f f r e Basins, B r i t t a n y , France. 15

L a t e Eocene t o Pliocene

Pechelbronne Basin & Mullhouse Basin, France 60

L a t e Eocene to E.O1 igocene

LanguedocMormoiron Basin, Gard B a s i n (France) 70, 28

L.Cretaceous Limestone t o E. Paleocene, do1 omi t e , E.Eocene l i g n i t e , gypsum, marl, a l g a l mats, vertebrates.

Lacustrine fluvial

L.M.Eocene

Dolomite, m a r l , sandy c l a y , g r i t t y 1 imestone.

Marine lagoon

Fluviolacustrine, subtropical & d r y seasons.

P a r i s Basin (France) 13A7 43, 70A

E.O1 igocene

P

t h i s volume

Limestone

Marine?

Pure beds

I1

Petrol iferous dolomite, clay, limestone, evapor it e s (anhydrite).

Provens (France) Vaix en Provens Basin 61

L. Eocene t o M. O l i g o cene

Gypsum, l i g n i t e marl

Durance b a s i n , Bresse, France. 61

L.Oligocene

Gypsum, l i g n i t e marl

Marginal m a r l ne , very t r o p i c a l

.

200 km2, pure and disseminated

P

s

S

w 0 m

LeLocl e ( S w i t z e r l a n d ) 33, 26

L.E. t o E.M. Miocene

Cel e s t i t e , v o l c a n i c ash, do1 omi t e , f i n e sand, c l a y redbeds.

Freshwater l a k e s , streams savannah

100 km2

P

Malvern, England (midlands) 16, 24, 40

Late Triassic

Marl, dolomite in joints e x t e n d i n g from base T r i a s s i c i n t o Devonian dolerite, etc. Redbeds, 1a t e r i t i c s o i l , red marl, i n sediments.

She1 f seas, gypsum lakes

Extensive Up t o 40% 10 m th.ick

S

Northwest S c o t l a n d 62

Devonian

Cal C r e t e , weathering h o r i z o n . Red sandstone

Arid, saline 1 akes?

P

Poland 020, D l O A

Te rt ia ryQuat e r n a ry b ou nda ry

Weathered basalt

?Ancient s o i 1s

P

R i v e r Onega Basin (Russia) near F i n l a n d 11

Carboni f e rous

Ca 1 careous redbeds, 1 imestone d o l o m i t e , marl, clay, sandstone, basic volcanics bauxite.

Nearshore marine f a n depo s i t s

60-70% o f c l aystone

P

Fergana Basin (Uzbekhistan, K h i r g i z h s t a n , Russia)

Neocomi anAptian, A1 b i an, Cenomanian,

Beneath do1 omi t e , o v e r c l a y sandstone. Gypsum i n

Arid, 1agoons & alkaline lakes w i t h

60-80% i n clay fraction o f 10m t h i c k clay, i n

P

G1

0 W

11, 48, 64, 18A, 79, 82 I

Tu r on ian t o Dani an. Palaeogene, Neogene

Cenomanian; commonest i n coarse c l a s t i c s as cement.

marine in f l uence calcretes (P1 iocene)

Cretaceous (16% t o t a l )

Cherkassk D e p o s i t (U k r a ine) 12,

E. Miocene

Clay, sand, some l i m e s t o n e bauxite, amphibolite.

Marine, s h a l l ow water, t r a n s g r e s s ve.

S i m i 1a r t o Georgia, U.S.A.

P

Moscow Synecl ise (Russia) & Russian P l a t f o r m . 71, 64, 47, 14

M-L, Carbonif e r o u s

Basalt, kaol i n i t e , bauxite

Margins o f deeply weathered highs, sha 1 ow marine.

Novilsk, Kureika R i v e r , N. S i b e r i a n P l a t f o r m (Russia) 64, 14

L. Devonian E. C a r b o n i f e rous ( T o u r n a s i on) A1 so m i d d l e t o upper Carboniferous

Limestone ( r a r e ) Coal, c l a y , sandstone, "a1 e u r i t e " , marl, vertebrates, dolomite, basalt intrusions.

Marine, tropical , low swamp vegetation. Epi c o n t in e n t a l sea s a l i n e lagoon. Diagenetic, ?hydrothermal.

Concretions i n 40 m t h i c k unit. Extensive.

P,S

Rybin Basin, I r k u t s k Amphitheatre, Olekmin, Lena R i v e r (S. S i b e r i a P l a t f o r m ) 14, 41 (Cambrian), 64

Late Cambrian and M. Carboniferous

Do1omi t e , fl u o r i te, anhydri t e , clay, carbonate primary dolomite

F l a t land, shallow m a r i ne , w i t h islands. M a r g i n a l marine red-beds. S a l i n e 1 agoon.

1-1.5 km extent + many others

Western Armenia (Russia) 36,

P1 iocene

Transitional t o evapori tes, explosive vol c a n i c s , opal , flRAPg6bree.c a l Ci te

?Non marine, lakes.

100 km2 6-30 m t h i c k

P

Caspian Sea 46.

P1 ioceneRecent

Clay, sand

Large S a l t Lake o f oceanic o r i g i n .

P

Mangyshlak P e n i n s u l a , Khazhakstan (Russia) 69,

E. 01 igocene

Sand, s i l t , c l a y manganese do1 omi t e

Beach and s h a l l ow marine

P

Kura Basin, Azerbaijan (Russia) 56,

01 igo-Miocene & P1 i o - P l e i s tocene

Mol asseclay, siltstone, sandstone, g r i t , carbonate, conglomerate

Weak a1 k a l i n e basin w i t h ferromagnesium m i n e r a l s i n source area. A r i d climate. Marine t o non-marine.

Disseminated i n clay. Very t n i c k sequence.

P

Donets Basin, Russia

M. Carboniferous

Karstic solution holes i n a n k e r i t i zed limestone, over coal seam. Calcrete.

Weathering?

Very extensive

P

P r ipya t Depress ion , Russia (Southern White Russia) 81

L. Devonian

Shale, e v a p o r i t e s (gypsum), do1 om1 t e , v o l canics. O i l shale.

Arid Extensive ?Non-mari ne. Lagoonal -marine Normal t o a1 k a l i n e

P

Gao Basin, Maland N i g e r , E. Soudan 50, 44, 32,

M.

Do1omi t e , c l a y , phosphate vertebrates, laterite, gypsum

Marine (marginal )

4000 km2 i n t h i n pure beds.

P

Tufa 1imestone

Spring deposits

Small

S

77,

Nam ib ia ( Southwest A f r ica )

Eocene

Modern-Qu

w c.

Senegal B a s i n 50,34

PaleoceneE. Eocene

Chalk, sandstone, marl, phosphate, glauconit e

Marine s h e l f

Rich

p,s

Gabon/Congo 32,17

MaastrichtianE. Eocene

Laterite, phosphate

Marine s h a f t

150km narrow c o a s t a l region.

P

Togo/Da homey 57

Eocene

G1auconi t e , sandstone, clay

Marine s h e l f

Ambosel i Basin Kenya 76, 63

E. Q u a t e r n a r y

Interfingers w i t h basalts & coarse c l a s t i c s . Dolomite, c l a y , (aeol i a n ) c a l Crete, gaylussite.

Lake

200 kmZ, 60 m t h i c k

N i g e r i a - N i g e r Basin

PaleoceneEocene

Blue shale, CG sandstone

?Nan marine (lacustrine)

?

M e t l a o u i Basin, T u n i s i a 55

L. Paleocene

Phosphate

Marine

Taguenout-Haguerat Basin i n NE M a l i N i g e r , 7, 44

Cretaceous

Laterit e

Tropical, m a r g i n a l marine

?

Morocco (Oul ad-Abdoun Basin, Khouribga Basin) 20, 18C

M a a s t r i c h t i an t o E. Eocene

Marl , do1 orni t e , phosphate

Marine

10 000 km2

Morocco (High & Mid A t l a s ) 188, 6A

Triassic

Clay sand, carbonates, evapori tes, vol canics

Arid, Marine

% o f the

P,S

The h i g h e s t Triassic deposits

S

T u n i s i a (Metlaoui Basin) 55

Paleocene t o L. Eocene

Phosphates

Arid, marine

Large

P

Ta r k a r o o 1 00 Bas in South A u s t r a l i a 8 , 3,

Miocene P1 i o c e n e

Interbedded w i t h and beneath dolomite, i n fine clastics. High strontium. Vertebrates

Non m a r i n e 1 a c u s t r i ne, Time o f max. marine transgression. F r e s h t o a1 k a l i n e . Savannah, l a k e s . semi a r i d , ( a 1t e r n a t i n g v e r y d r y and wet?)

50-80% clay fraction; some p u r e beds, up t o 2 m thick.

P

Ipswich Basin, Queens1and

L.

As above, b a s a l t , o i l shale.

Freshwater

T h i n beds

S,P

Lake E y r e B a s i n , South A u s t r a l i a 6, 21, 68, P i r i e - T o r r e n s Basin South A u s t r a l i a . 22 Eucla Basinbordering channels (S. A u s t r a l i a , Western A u s t r a l i a ) 42

As f o r T a r k a r o o l o o Basin.

60 000 km2

P

As f o r T a r k a r o o l o o B a s i n

5 000 km2

P

P o l d a Trough, E y r e Pen., S. Aust. ( p e r s . comm. R. F l i n t , SADME) Mysore, "Deccan Traps" ( I n d i a ) 10, 4A, 45, 57

Eocene

?L. Miocene o r P1 iocene

Clay, d o l o m i t e

Non-ma r i n e i n ancient river valleys.

Low t o h i g h

s, p

?L. Miocene o r

Clay, d o l o m i t e

?Non-mari n e

?

S

Calcareous and c h e r t y rocks i n t e r bedded w i t h basal t s .

?Weathering horizons, a r i d lakes.

Extensive and t h i c k

P

P1 i o c e n e

L. C r e t a c e o u s t o Paleocene

w c w

China ( J i a n g s u ) (Zhang , t h i s vol ume )

.

I,

'I

(Guangxi Zhuang)

'I

( J iangxi )

?

Miocene

Basal t i c py roc1a s t ics

( S i chuan) Permi an

Do1 omi ti c/ 1 imestone ?Hydrothermal

? Permi an

S

Olivine basalt Cherty limestone, do1 omi t i c limestone, limestone.

Marine

Se e r a 1 thousand km

I

S

315

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322

11.2 CONTINENTS Wherever p o s s i b l e t h e most r e c e n t comprehensive r e p o r t on a s i n g l e b a s i n g i v i n g d a t a on s p e c i f i c age and l o c a l i t y has been i n c l u d e d .

Otherwise,

m u l t i p l e r e f e r e n c e s a r e given.

1c.

See 01A.

1A.

See 131.

1B

See D2.

10.

Aneesuddin, M.,

1971:

The c l a y m i n e r a l p a l y g o r s k i t e .

J. Miner. Met.

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Nathan, Y and S t a r i n s k y , A,,

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Azhgirevich,

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I z v . Akad. Nauk b e l o r u s s . S.S.R.

(Minsk.),

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See D2A.

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Kaimakov, A.K., 1978.

Kirichenko,

I.V.,

Savushkina, M.A.,

and Yesipova, G.A.

U k e n i t i s e p i o l i t v i z h b e s t r y a k a k h Aleshinskogo skarnovo-

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Sedimentol.,

30: 11-32.

337

AUTHOR INDEX

Alvarez, A . ,

253

Blackmon, P . D . , Callen, R.,

Mackenzie, R . C . , 137

I

177

M a r t i n de V i d a l e s , J . , 149

177

Mashhady, A . S . ,

Casas, J . , 149

Oades, J . M . ,

Castillo, A.,

Otsuka, R . ,

87

199

211

Dixon, J.B., 181

Ovcharenko, F.D.,

Esteoule-Choux, J . , 75

Post, J . L . ,

87

Galan, E . ,

Shadfan, H . ,

Hasnuddin S i d d i q u i , 243

Singer, A . ,

187 169

Hay, R . L . ,

125

Starkey, H.C.,

Hodge, T . ,

199

Stoessel, R.K.,

Imai, N.,

211

Janke, N . C . ,

59

159

Kukovsky, Y . G . , Leguey, S.,

137 125

Turchenek, L.W.,

Isphording, W.C.,

149

233

233

159

Weaver, C . E . ,

39

Wilson, M . J . ,

177

Zhang Renjun, 251

199

This Page Intentionally Left Blank

339

SUBJECT INDEX

Africa, 5,6,7,12,14,19,22,23,56,57,169 Agate,

173 75,78

A1-Mg antagonism,

__ ,

deposits,

-, River,

smectite relations, 183 184

micrographs,

182

75

Armorican Massif palygorskite,

Amboseli Basin, Kenya,

--- , origin,

126

126

__ , geological

--- ,

setting,

-- , geochemistry,

126

micrographs,

79,80,81,83

--- , TEM

micrographs,

79,80,81,83

X-ray diffraction, 83

Asbestos,

125

78

--- , SEM --- ,

130

Amboseli sepiolite,

233

__ , stability relations, 130 -- , reaction kinetics, 131

Asia,

-- , water

chemistry,

Australia, 3,6,7,10,13,19,26,30,

America,

5,23,59.169

Analcime,

127

Andesite,

59

Antigorite,

130

31,133,170,171,173,169,199

-, palygorskite in soils,

200

172

Austria, Barium,

7

Barite,

153

224

Appalachicola Embayment, 40 Aptian-Albian,

13,23,29

159

-- , characteristics,

161

-- , I R

--- , compositional formation,

Ballarat sepiolite,

-- , chemical

6

Arabian Peninsula palygorskite,

--- ,

5,19,233

53

Apatite.

Arabia,

170

Atriplex,

71,226,237

Amphibole,

180

178,179

Armorican Massif,

134,135

137,145

__ , map,

soils,

--- , X-ray diffraction,

126,131

Amargosa Desert,

soil clays,

--- ,

--- , TEM

52

Altamaha River,

178

location map,

--- , mineralogy

251

Algeria,

--- ,

diagram,

183

183

178

analysis,

spectra,

155

163,164

__ , location map, 160 -- , origin, 161,164 __ ,

thermal characteListics, 163

340

-- , X-ray

162

diffraction,

Basalt, 8,25,26,27,30,31,126,185, 188,228,234,244,249

Basaltic glass, Basin, Bauer,

4,6,7,8,30,169,171

Calcrete,

1,29,138,244

-, dome,

133,134

Caliche,

127,133,134,169,171 126,137

California,

-, Inyo

19

County, 137,159

-, Bauru,

19

-, Panamount

-, Duero,

89

Cambrian,

-, Ebro, -,

89

-, Tajo,

-, Tertiary, Spain,

75 88,89,90

87,97,125,132,133,149,153,161,

76

170,192,211,212,225,234

4,29

Benfica palygorskite,

7,12,25,39,71,75,78,83

Carbonate,

Carolina,

Belize, 59,65

Bentonite,

1,12,27,31

Carbon,

-, Tertiary, France,

Beidellite,

19,24,29,30,31,32

Campeche, 65

91

Basse Loire,

39

Cataclastic, 215 116

Cement

-, calcareous,

111,234

Biotite, 41,42,47

-, clay,

Blake Plateau, 39

-, siliceous,

Boehmite, 59,61,65

Chabazite,

Bohu-Robien palygorskite, 76

Chalk,

Bole,

244

Brazil,

159

31,161

Campanian,

Paris, 19

Valley,

149,153,155

149 149,153,154

138

8

Chalkedony, 151,154,228

19

Champoten River, 61

Breccia, 125,128,130,133,135

Chemical composition

Byelorussia, 234

-- , Ballarat

Cainozoic, 6,12,31,57 Calcareous ooze, 8,9 Calcite, 25,51,53,75,78,84,105, 112,127,135,143,153,154,155,161,171, 172,173,181,202,215,251

108,

sepiolite,

165

__ , La Camalia mine, 50 __ , Lake Tecopa sepiolite, 142 __ , Indian Deccan palygorskite, 245 __ , Japanese palygorskite, 215 __ , Japanese sepiolite, 219

-- , Jordan Valley

clays,

196

34 1

-- , S.E.

United States palygorskite.

__ , Sinya -- ,

49

129

Beds,

Clinoptilolite, 56,138,140,145 Clinopyroxene, 221

South Australian palygorskite, 204

-- , Torrejon

palygorskite,

-- , Vallecas

sepiolite, 98

-, palygorskite,

109

-- , Yucatan

clays,

_-, Yucatan

palygorskite, 69

Coniacean, 29,30

61,63

Conglomerate, 87, 116,149,155 19

Congo,

Cherkassk bentonite, 234

Coorong,

Cherkassk palygorskite, 234

Continental drift,

-- ,

cross-section,

Corrensite, 55,56

-_,

location map,

-- , origin,

__ , TEM

161

Coating, sepiolite,

236 235

7,30,208 39

Cretaceous, 1,7,13,19,22,24,26,30,

237

31,39,56,59,226,149,187,188,221,

micrographs,

238

223,237,243

Chert, 7,87,97,99,103,113,161,244,252

Crimea, 234

Chiaparas Laramide, 5 9

Cristobalite,

China, South, 251

39,41,53,108,115,

151,154,155

Chinese (south) sepiolite, 251

Cross-sections, lithological,

-- , Jungdezhen,

--_, Cherkassk palygorskite, 236

251

-- , Leping,

252

--_, Duero Basin, 102

-- ,

252

--_, Lake Tecopa, 139

Liling,

--_, Lebrija palygorskite,

Chinese porcelain industry, 251 Chlorite, 59,61,63,66,87,107,114,

115,

143,160,181,220,227

Chromite deposits, Climate,

-,

--- , Sinya dome,

218

134

--- , South Australian

arid, 8,9,26,27,30,31,87,118

subtropical, 57,84

-, palygorskite

formation, 57,58,

palygorskite

207

-, semi-arid, 1,26,31,87,118 -, mediterranean, 1,5,8,26,30

119

U.S. palygorskite, 41,43,

46

75

-, tropical,

--- , SE

104

65,

___ , Tajo Basin, 92,94,96, 113 ___ , Torrejon palygorskite, 117 ___ , Vicalvaro sepiolite, 97 -_-, Yunclillos palygorskite, 99

342

--- , evolution,

19

Deccan Traps,

154,156

Deccan Trap Formation, 2 4 3

___ , evolution diagram,

Deccan Trap palygorskite, 2/13

__, feldspathic

-, Timsanpalli

___ , location map, 1 5 0 --- , Madrona formation, 149 __, optical micrographs, 152

palygorskite, 2 4 3

--- ,chemical composition, --- , formation,

248

--- , TEM micrographs, --- , thermal analysis, --- , uses, 248 --- , X-ray

245

247

Dessication features, 48

sands, 153

___ , sandstone, paraconglomerate,

246

diffraction, 246

155

153

-_-, siliceous white

sands, 151

Dune systems, ZOO Duricrust , 173

Devon, 1 , 1 2 , 2 7 , 3 1 , 2 3 4 102

Ebro Basin, Diatom, diatomite, 4 1 , 4 3 , 5 4 , 5 6 ,

Egypt, 7 , 172 103,118,145

Enstatite, 2 4 4 Dickite, 222 Environment, conditions Diopside, 159,161 Diorite, 234

-, anoxic, -,

30

brackish, 8 , 1 9 , 3 1 , 3 9 , 4 2 , 4 9 , 5 6 , 8 4 ,

Distribution palygorskite, temporal, 118 1,39,56

Dolomite, 7 , 2 , 1 9 , 2 5 , 3 0 , 3 9 , 4 2 , 4 5 , 4 7 , 48,49,51,53

56,59,66,67,69,75,78,

8 4 , 101,102 107,108,112,115,125, 127,128,132

+35,143,144,148,155,

214,222,227,234.

Dolomitization gradient, 53

-,

clastic, 4 , 7 , 7 0

-,

continental, 8 7 , 1 1 2 , 1 4 9

__ , epicontinental, 1 , 1 0 , 1 9 __ , estuarine, 42 -_, evaporitic, 4 , 7 , 1 9 , 2 7 , 3 1 , 5 6 -- , hypersaline, 56,161

-- , lacustrine, 4 , 1 9 , 2 4 , 3 1 , 7 5 , 7 7 , 8 7 ,

Dolostone, 214,215,217,230 1 1 2 , 118,161

Doming, 133 DSDP,

-- , lagoon,

lagoonal, 2 8 , 4 4 , 4 7 , 4 8 ,

1-37

49,51,59,65,71,75,112,230

Duero Basin, 89,101 Duero Basin palygorskite, 1 0 1 , 1 4 9

-- , littoral,

__ , marine,

76

2,56,75,76,118

343

-- , metamorphic, -- ,

4,12

pedogenic, edaphic, 4 , 2 5 , 3 1 , 5 9 , 6 1 ,

151

Florida, 4 , 7 , 3 9 , 4 3 , 4 4 , 8 4 Fluorine, 165 Fluviatile sediments, 49,184

-- , perimarine,

4,7,8,9,14,23,31,39,

56.75 , a 7

Fossils, 4 8

-- , phreatic, --, playa,

Foliation, 215

25

France, 19

4,7,30,126,135,159

-- , pyroclastic,

4

-,

Basse Loire, 76

-, Bay

o f St. Brieue,

-- ,

saline, 7 , 4 3 , 5 9 , 7 5 , 1 4 3

-, Campbon, 7 5 , 7 8

-- ,

schizohaline, 3 9 , & 9 , 5 6

-, Campeche, 6 5

-- ,

shelf, 7 , 8 , 2 4 , 3 0 , 7 0

-, Langon,

-- ,

tidal,

39,44

75,78,83

-, Loutechel, 7 5 , 8 3

1,7,19,23,25,26,27,32,70,75,

Eocene, 102,243

-, Paris

Basin, 29

-, Point Noire, 19

Equator, 2 , 9 , 1 2 , 2 2 , 3 1

-, Quessoy, 7 7 , 8 3

Erionite, 138

-, St. Seglin, 7 5 , 7 8 , 8 3

Escarcega, 6 5

Franclandite, 2

Etzna, Europe,

76

69

Fullers Earth, 2

12,19,56,169

Evaporite, 5 9 , 1 6 0

Gaylussite,

Experimental synthesis

Georgia,

-- , palygorskite,

Gibraltar,

115

127

4,7,39,43,84 14,57

Glass shards, 71 Falcondite, 2

Glauconite, 5 6

Fault, 2 1 4 , 2 1 5 , 2 1 6 , 2 2 5 , 2 2 8

Gneiss,

Feccal pellets, 5 6

Goethite, 107

Feldspar, 53,97,107,108,112,114,115,

Granite, 8 3 , 9 6 , 1 0 5 , 1 4 9 , 1 5 3 , 1 5 4 ,

127,140,143,153,173,181,184

153,154,179

185,221,223,234 I

Fergana Trough, Fissuring,

19

222,227

Guatemala, 5 9 , 6 5 Guadalquivir Basin, 1 0 3

344 71

Gulf Coast,

Japan,

Gulf of Mexico, 7,14,19,39 Gypsum,

7,101,103,112,161,171,173,187,

-, Fukuoka,

212

-, GreenTuff

Region,

-, Kuzu,

188,192,194,197

221

159,211,212

Japanese sepiolite, palygorskite, Halite,

161 21 1

Hematite,

221,222,223,224

Holocene,

7,8,23,30

--_, location map,

213

Japanese palygorskite, 212 173,221

Hornblende,

Hornfels, 222 Hydromica, 234,237 Hydrothermal alteration, 221 Hydrothermal dolomitization, 221,223, 224

Iceland spar, 251

__ , chemical composition, -- , genesis, 217 -- , Hanezuru, 215 -- , Kamioka, 217 -- , Kuzuu, 212 -- , Ogano, 212,214 -- , TEM micrographs, 216

215

97 ,105,107

108,

Japanese sepiolite, 218

115,116,118,127,127,

38,140,149

151,

-- , hydrothermal experiments, 217,

154,156,160,169,184,

91,248

Illite, 47,75,77,84,87

-, formation,

229

-- , genesis,

78

Ilmenite, 65

229

Japanese sepiolite in serpentinite,

India, 10,19,26

218

Indigo, 6 8

--- , chemical composition, 219 --- , Oeyama sepiolite I, 218

Infra-red spectra

--- , Oeyama

Indian palygorskite, 243

-- , Ballarat

sepiolite,

163,164

Interdunal flats, 199,200,202,208,209

--- , Yoshikawa,

171,173

225

Iraq,

171,173

--- , in

-

copper mineralization,

Israel, 22,172,187

223

218

Japanese sepiolite from "Karst",

Iran,

Iron

sepiolite 11, 220

limestone caves, 227,229

--- , Karasawa, -__, Kasuga,

212,225

226

345

Japanese sepiolite in metallic deposits, 22 1

La Camelia palygorskite, 44,46

--- , Atakani,

____ , Waka ____ ,

221

Lacustrine deposits, sediments,

Sen-niu, 223

188-1 96,199,230

sepiolite I and IT, 224

Japanese sepiolite in Tertiary sediments,

-___ , &an,

Lake Tecopa sepiolite,

--- , formation,

228

--- , geology,

187

__ , geological map, __ , soils, 193

189

Jordan Valley palygorskite,

--- , chemical

composition,

_-_, mineralogy, --- , origin,

142

140

143

137

___ , stratigraphic section, ___ , X-ray diffraction, 141

171,173

Jordan Valley,

137

composition,

--- , description,

227

____ , Seikon,

161

Lake Panamint,

--- , chemical

227

Jordan,

Labradorite, 244

139

Laterite, 184,244 187 196

191

-,

landscape, 83

-, weathering,

54

Lead-zinc mineralization, 217

196

Lebanon, 22,172

___ , TEM micrographs, 195 --- , X-ray diffraction, 192,194 Jurassic,

13,19,25,31,32,187,188

Kalahari,

172

Lebrija palygorskite-sepiolite, 103

--- , genesis,

118

___ , location map,

104

Lenses, palygorskite, sepiolite, Kaolinite,

41,43,56,59,61,6~,64,65,77, 53

107,108,149,151,154,155,172,191,196

Leping White Earth, 251 203,222

Limestone, 7,25,59,61,64,69,71,75, Karst, 39,211,229 103,105,149,153,159,188,215,216,

Kenya ,125 221,222,224,225,227,230,244,252.

Kerolite, 125,127,128,130,134

-, stability v. sepiolite,

-, dolomitic,

161,172,174,179,187,

130,131,132, 202,208,217

135

Lisan marl, Kilimanjaro,

188

125,126,133

Loughlinite, 2

346

Maastrichtian, Madagaskar,

19,30

Meerschaum, 2 , 1 2 5 , 1 2 7 , 1 2 8 , 1 3 0 , 1 3 3

3

Mesozoic, 1 2 , 5 5 , 5 6 , 7 3 , 2 1 2 , 2 2 5

87

Madrid,

Messinian salinity event, 8 , 1 9 , 2 2 100

Magan sepiolite,

Metamorphics, 5 9

Magnesite, 220

Mexico, 5 9

Magnesium metasomatism,

223

Mica, 47,49,107,143,153,172,182,

65,244

Magnetite,

184,191,226

-, Cherkassk palygorskite,

-, Duero

Basin,

234

Eckert projection,

-,

Iberian Tertiary Basins, 8 9

-, Japanese -, Jordan

-,

2

palygorskite, sepiolite, 213

Valley, geology,

189

Kenya, Amboseli Basin, 126

-, Lake

Tecopa, 1 3 8

-, Lebrija -, Massif

Trench, 1 2 , 1 9

Armorican palygorskite, 76

-, Mercator projection, 2,10,22

-, paleogeographic, 40 -, Polar

projection, 2

-, Reconstructions,

53,54,57,70

lower, 4 2 , 4 3 , 4 4

Mixed layer clays, 6 3 , 6 9 , 7 2 , 1 0 7 , 154,172,191,226

Mojave desert, 137 Montmorillonite, 2 9 , 3 1 , 3 9 , 4 3 , 4 7 , 48,49,50,51,56,72,138,145,160,

deposits, 104

-, Marianas

40,41,221,224,228,234,251

-, middle,

150

-,

-,

13,19,23,24,26,30,32,39,

Miocene,

%PS

3

234,237 12,172

Morocco,

Mounds, domes,

125

Mountain leather, 9 4 , 1 0 1 , 2 2 7 , 2 2 9 , 251

-, skin,

233

-, cork,

233

-, S.E.

South Austrblia, 201

Mudcracks,

-, Tajo

Basin, 90

Mudstone, 137,138,140,143,228

-, Torrejon

Basin, 106

-,Yucatan,

60

-, Yucatan, geology,

Muscovite,

48,49

116

Near East, 169 68

Neogene, 1,8,9,23,27,31,65,103,188, Marble, dolomitic, 226 237

Marls, 87,111,149,187,244 Nevada, Maya Blue,

67

159

347

-, Amargosa desert,

126,131

-, deposits, 134,135 -, River, 137,145 172

New Mexico, New Zealand,

Palaeozoic, 31,56,212,225,234

-, Chichiby System, Palagonite, 244

Palygorskite in calcretes, caliches, 17 1

3,25

Nickel, 220

coating, 199

-, deposits, Nontronite,

212

237

crusts, 234

228

disintegration, 169,171 environment, 169

Ocala Uplift, High, 4 0 , 4 2 , 5 3 "Event " , 1 1 7 Ocean fibers, 4 8 , 5 1 , 1 4 0 , 1 5 3 , 1 8 5 , 1 8 7 ,

-, Atlantic, 3 , 6 , 8 , 1 3 , 1 4 , 1 9 , 2 3 , 3 9 , 4 0 , 4 2 ,

191 ,194,196,206,248 43,57,58

films, 214,215

-, Indian,

3,6,8,9,14,19,27

-, Pacific,

4,8,12,13,19,27,29,30,31

fissure filling, 211,222,223 Palygorskite formation by

Oligocene, 1,19,22,25,26,30,32,41,57,

-- , crystallization, 1 , 5 9 , 6 9 , 1 1 4 , 75,116,227,234

-, Tampa

21 7

Formation, 3 9 , 4 0

Olivine, 244

-- , epigenesis, 48

-- , mineralization, 237

Opal, opaline, 3 9 , 4 1 , 4 8 , 5 3 , 5 7 , 1 2 7 , 1 4 9 ,

-- , precipitation,

75,84,87,115,

151,154,220,226,230 137,144,145,173,211

Ore, 2 , 2 1 7 , 2 2 3 , 2 2 4 , 2 3 4 Organic matter, 1 9 9 , 2 0 8 , 2 0 9 Ostracode beds,

-- , slumping,

1,6,7,9,30,31

-- , turbidity

current, 1 , 6 , 1 4 , 3 0 ,

145 31

Oversalt layer, 234 Oxygen isotope, 29

-- , weathering -- , windblown

of basalt, 249

dust, 1 , 6 , 9 , 2 9 , 3 0 , 3 1

Paleocene, 2 4 , 7 8 , 8 3

Palygorskite, intertrappean, 244

Palaeoclimate, 2 , 3

-,I

Palaeocontinental, 8

Palygorskite origin

Palaeornagnetic, 2

-- , alteration

Palaeosols, 169,171

morphology, 199,206

166,172

1,2,50,69,78,159,

~

348

-- ,

authigenesis,

Persian Gulf, 78

-- , detrital, 4 , 5 3 -- , diagenesis,

pH 3,51 ,54,55,56,87,113,114,115,

8 7 117,i 18,149,151,

154,155

115,132,143,145,154,161,170

Phanerozoic, 56

-- , hydrothermal 29,30,31,56,2

1,2,4,12,25,26,27, 4,234

Phillipsite, 138 Phosphate, 7,12,19,39,41 , 5 3 , 5 6 , 6 7 ,

-- , neoformation 3 , 4 , 5 , 1 4 , 3 0 , 7 8 , 1 1 7 , 149,155,177

230

Pilolite, 2

-- , orthochemical,

--, pedogenic,

39

Plagioclase, 71

169,172,197,199,208

--, replacement,51,55

-- , transformation, 3,1

Plagiorhyolite, 224 Pleistocene, 1 ,7,22,125,127,134,137,

4,ll-,116,118,

237

139,159,199

Pliocene, 1,10,19,22,23,30.103,104,

Palygorskite refractive indices, 214-228

134,161

Palygorskite in soils, 70

Porphyrite plagioclase, 228

Palygorskite stability, 54,55,169,172

Precambrian, 126,132

-, surface properties,

-, basement,

239

178,179

-, synthesis, 115

Pyrite, 107,114,226

-, textural transitions, 171

Pyroclastic, 59,69,71 ,228,251

-.

table of occurrences, 176

Palygorskite uses

-- , Torrejon, --, USSR,

Pyrophyllite, 107 Pyroxene, 71,237

109

Quartz, 39,48,65,70,71,83,97,105, 240

-- , Vallecas,

107,112,115,130,143,149,150,153, 98, 253 154,155,173,184,203,204,214,222,

Palygorskite veins, 234 225,226

Pelagic o o z e , 22 Quaternary, 23,104,187,188,200,202 Pennsylvanian age, 59 Quintana Roo, 65 Perm, 1,12,32,234 Permian Izaru Formation, 2 2

Rana, 105,107,116

- ,,Nabeyama

Rus s ia , 2,4,12,27,3 1

Format ion, 2 1 2 214

-, limestone,

252

Russian platform, 234

349

Rubefaction, 1 1

Sepiolite fibers, 214,216,220,224, 225,228

Sabkha, 7,170,

73,183

Sepiolite formation by, Sacalum, 67,69 Sand, 43-49,

-, mounds, -, dunes,

-- , crystallization, 211,225,228,230

149-153

-- , hydrothermal

solutions, 211,217,

125 220,224,225,227,229,230

31

-- , precipitation, 225

Sandstone, 87,116,149,153,155,179,188,

-- , supergene

processes, 211,217,

227,228,244 220,222,229

San Martin de Pusa palygorskite, 100,116 Sepiolite in Japanese Tertiary Santonian, 30 deposits, 211 Saponite. 100,107,112,115,116,118,142, 154,155,161,166,183,252

-___ , in karst regions, 211,212,229 -___ , in metallic mineral deposits,

Saudi Arabia, 170,172,173 21 1

Savannah River, 40,43

-___ , in

serpentinite, 211

Scanning electron micrographs, 48

___ , Massif

Sepiolite in limestone, 252 Armorican palygorskite, 79-83 Sepiolite-Mg, 226,227,228

Schist, 83, 79

-, nickeliferous,

221

Sea

-, epeiric, 7,30

-,

-,

porosity, 259

-,

refractive indices, 214,218,220,

inland, 1

-, Mediterranean, -, Red,

221,222,225,226,228 8,13,19,27

Sepiolite, rheological behaviour, 27

-, shallow,

263,264,265 1,44,48,75,84

-, sorbtive

properties, 263,266,267

Sepiolite alpha, 220,224,225,227,228,229

-, beta,

-, structure, 220,224,225

-, cation

exchange capacity, 257

-, cavity

filling, 226

-, coating,

-, surface area, 258 -, u s e s , 253 Sewanee River, 42

161

-, composition, -, Fe,

254,255,256,257

Serpentinite, 25,130,218,220,222, 257 224,234

226,227,228

Shatsky Rise, 8,28

350

Shrinkage cracks, 153

-- , distribution, genesis, 208 -- , location, 200 -- , map, SE South Australia, 201

Siberia, 12

-_, TEM micrographs, 206,207

Silicrete, 173

-_, X-ray

Sinya Beds, 125,127

-,

Salorthid, 179

-,

swamp, 208,209

Shale, 188.234 Shell, 43,47.51,52,53

-- , chemical composition, -- , cross-section, 134 -- , exposure photo,

129

-, Torrifluvent ,

'

128

Spanish Tertiary Basins, 88,89,90,

-- , dome, 125,127,133

111

--- , palygorskite formation models,

Skarn, 217,221,222,223,224,234 Slate, 107,108,110.114.115

119,120

---, palygorskite genesis,

Slaty basement, 87,114,115 Srnectite, 3,29,39,50,59,63,65,75,77, 80,83,84,87,149,171,172,181

,191,194,

196,199,208,209,218,222,230,248

Soil, 1 , 3 , 4 , 6 , 7 , 8 , 1 2 , 3 0 , 3 1 , 3 9 , 4 3 , 4 4 , 4 7 , 40,6 1,62,70

-, -,

78,

---,palygorskite

87

types

Sponge spicules, 53,54 Stevensite, 50,97,112,129,132-135, 221,230,252

Swamp, 7 7 colluvial, 187

arid, semi-arid, 3,151,154,169,177

-, Holocene,

170,179

South Yemen, 177

-- , origin, 132

-, alluvial,

diffraction, 205,206

170

Swinestone, 252 Switzerland, 25 Syria, 187

lateritic, 220

-, Natrixeralf,

Talc, 59,61,63,66,125,130,131,221-229, 170 25 1-252

-, Reg,

170

Tanzania, 127 Soil rendzina, Dalygorskite, 199

__ , chemical

analysis, 204

-- , clay mineralogy,

203

__ , cross-section, 202 -- , description, 203,204,209

Tatar ASSR, 234 Tajo Basin, 91

-- , clay

mineral genesis, 112

-- , eastern

sub-basin, 100

-- , evaporitic facies, 94

35 1

detrital facies, 93

Tuff, 137 ,138,143,228

geological setting, 91 Urals, 234 lithology, 91

USA, 4,39,233 lithostratigraphic correlation, 94 Ukrainian palygorskite, 233 transition facies, 93 Uses, sepiolite, 253 Tertiary, 3 0 , 3 9 . 7 1 , 7 5 , 8 4 , 1 4 9 , 1 8 7 , 1 8 8 , 2 0 2 ,

__ , animal nutriton, 277 -- , anticaking agent, 272

227,228

Tethyan, 19,57

_-, asphalt coating, 270

Texas, 169,172

-- , catalyst

carriers, 268

Thenardite, 161

--, cigarette filters, 273 Thermogravimetry

-- , cosmetics, 280 -- , deodorizing agent,

-, Ballarat sepiolite, 103

271

Tokyo, 212

-- , detergents, 278,279

Toledo, 87

-- , drilling

Tierra del Vino, 103,105

-- ,

fluids, 283

fertilizer suspensions, 281

Torrejon Basin, 105

-- , clay mineral -- , geologic -- .

-- , filteraid, genesis, 114

-- , grease

272

thickener, 282

setting, 105

_-, NCR

paper, 282

lithology, 105

-- , mineralogy. -- , palygorskite

-- , paints,

--,pharmaceuticals, 270 formation, 117

-- , phytosanitary

Transmission electron micrographs, 257

--_,

Arabian peninsula palykorskite, 184

--_, Lake

Tecopa sepiolite, 140

--_, Massif

--_, Rendzina palygorskite, 206,207 --- , Timsanpalli, India, palygorskite,

carrier, 272

-- , plastisols, 274

-- , polyester, 269 -- , rubber

Armorican palygorskite, 79-83

--- , Vallecas

270

107

-- , seed -- ,

filler, 275,276

carrier, 281

soil conditioner, 280

247

Uses, Torrejon palygorskite, 109 sepiolite, 99

-, SSSR

palygorskite, 240

Tremolite, 161,221,224

-, Vallecas

palygorskite, 98

Turbidte, 7,8,22,27,29,30 Uzbekistan, 234 Trias, 1,12,13,23,26,32,57,212

352

Vallecas, 87

Yucatan, Mexico, 177

Vallecas-Vicalvaro sepiolite, 97

-- , location map,

--- , chemical analysis, 98

Yucatan pedogenic clays,

--- , properties

--- , chemistry, mineralogy,

and uses, 98

--- , TEM micrographs,

60

61

--- , origin, 62

99

Vein, 1,25,26,31,127

Yucatan detrital clays, 65

Veinlet, 214-227

--- , origin, 65

Venezuela, 25

Yucatan primary clays, 6 6

'

Vermiculite, 177

--- ,

Volcanic ash, 31,63,66,69,70,71,137,138,

--- , location map, 6 8

chemistry and mineralogy, 6 9

--- , origin, 6 9

143,145,230

Volcanism, 30

--- , palygorskite-sepiolite, 67

Volcanic sediments, 1,29

--- , talc

Volcanoclastic, 4

Yunclillos sepiolite, 99

and chlorite, 66

-- , cross-section,

99

Wadi-ar-Rimah, 177 Wall rock alteration, 223.223

Zeolite, 39,137,138,143,145

Wollastonite, 221,230 X-ray diffraction

-- , Arabian

peninsula palygorskite, 182

-- , Armorican Massif palygorskite, 83 -- , Ballarat sepiolite, 162 -- ,

Jordan Valley clays, 194

-- , Lake Tecopa sepiolite, 140 -- , Rendzina palygorskite, 205,206 -- , Tajo Basin clay, 95 -- , Timsanpalli,

India palygorskite, 246

-- , Torrejon Basin clay, 110 -- , Yucatan pedogenic clays,

-- , Yucatan

62

residual soils, 6 4

Xylotile, 219,226,228