Deep-water sandstones, Brushy Canyon Formation, West Texas (AAPG Course Notes 40)

AMERICAN ASSOCIATION OF PETROLEUM GEOLOGISTS CONTINUING EDUCATION COURSE NOTE SERIES #40

Field Guide For AAPG Hedberg Field Research Conference - April 15-20,1999

Deep-Water Sandstones, Brushy Canyon Formation, West Texas

R.T. Beaubouef, C. Rossen, F.B. Zelt, M.D. Sullivan, D.C. Mohrig, G D.C. Jennette Exxon Production Research Co. with significant contributions from J.A. Bellian, S.J.Friedman, R.W. Lovell, D.S. Shannon and the rest of the EPRCo. Deep-Water Reservoirs Group

Field Guide For AAPG Hedberg Field Research Conference:

DEEP-WATER SANDSTONES, BRUSHY CANYON FORMATION, WEST TEXAS

Published by the Education Department of The American Association of Petroleum Geologists Copyright O 1999 by The American Association of Petroleum Geologists All Rights Reserved Printed in the U.S.A.

ISBN: 0-89181-189-3

April 15-20, 1999

AAPG grants permission for a single photocopy of an item from this publication for personal use. Authorization for additional copies of items from this publication for personal or internal use is granted by AAPG provided that the base fee of $3.50 per copy and $.50 per page is paid directly to the Copyright Clearance Center, 222 Rosewood Drive, Danvers, Massachusetts, 01923 (Phone: (978) 750-8400). Fees are subject to change. Any form of electronic or digital scanning or other digital transformation of portions of this publication into computer-readable and/or transmittable form for personal or corporate use requires special permission from, and is subject to fee charges by, the AAPG.

R.T. Beaubouef, C. Rossen, F.B. Zelt, M.D. Sullivan, D.C. Mohrig, and D.C. Jennette

Cover: Panoramic photograph of the western escarpment of the Guadalupe Mountains showing the northern 10 krn of the Brushy Canyon outcrop belt at the northwest margin of the Delaware Basin. The basin margin area is to the left in this view, and the basin center is toward the right. In this setting, the Brushy Canyon Formation is an onlapping wedge comprised of siltstone dominated slope facies with large, sandstone filled submarine canyons and slope channels. These channel complexes are oriented southeasterly and represent former point sources of siliciclastic sediment delivered to the Delaware Basin.

Exxon Production Research Company with significant contributions from J.S. Bellian, S.J. Friedman, R.W. Lovell, D.S. Shannon, and the rest of the EPRCo. Deep-Water Reservoirs Group

THE AMERICAN ASSOCIATION OF PETROLEUM GEOLOGISTS (AAPG) DOES NOT ENDORSE OR RECOMMEND ANY PRODUCTS OR SERVICES THAT MAY BE CITED, USED OR DISCUSSED IN AAPG PUBLICATIONS OR IN PRESENTATIONS AT EVENTS ASSOCIATED WITH THE AAPG.

AAPG Continuing Education Course Note Series #40 This and other AAPG publication are available from:

Published by The American Association of Petroleum Geologists lhlsa, Oklahoma, U.S.A. Printed in the U.S.A.

The AAPG Bookstore P 0 Box 979 Tulsa OK 74101-0979 Phone: (918) 584-2555 or (800) 364-AAPG (USA) Fax: (918) 560-2652 or (800) 898-2274 (USA) www.aapg.org

Geological Society Publishing House Unit 7, Brassmill Enterprise Centre Brassmill Lane, Bath, U.K. Phone: +44 1225 445 046 Fax: +44 1225 442 836 www.geolsoc.org.uk

Australian Mineral Foundation AMF Bookshop 63 Conyngham Street Glenside, South Australia 5065 Australia Phone: +61 8 8379 0444 Fax: +61 8 8379 4634 www.amf.com.au/amf

Affiliated East-West Press Private Ltd G-1/16 Ansari Road Darya Ganj New Delhi 110 002 India Phone: +9l 11 327 9113 Fax: +91 11 326 0538 E-mail: [email protected]

Table of Contents Pages

..

Introduction and Overview ................................................................................................................................................................................................................................... 11-12 Outcrop Localities ............................................................................................................................................................................................................................................ .1.1.5.3 Slope systems 1 .1. 1.7 Upper slope canyons and channel complexes ............................................................................................................................................................................ 2 1.2.3 Middle slope channel complexes ................................................................................................................................................................................................

..3.1. 3.9 Base of slope channel complexes................................................................................................................................................................................................ Basin floor systems 4.1.4.8 4 . Basin floor channel complexes ..................................................................................................................................................................................................... Proximal basin floor fan ............................................................................................................................................................................................................... .4.2.4.4 Medial basin floor fan ................................................................................................................................................................................................................... 4.5.4.8 Basin floor sheet complexes .......................................................................................................................................................................................................... 5.1.5.3 Extended Bibliography pages ......................................................................................................................................................................................................................... ..6.1. 6.2

-

Introduction

Reaional Bas

Exceptional oblique-dip exposures of submarine fan complexes of the Brushy Canyon Fm. allow reconstruction of channel geometries and reservoir architecture from the slope to the basin floor. The Brushy Canyon conslsts of 1,500 ft. of basinally restricted sandstones and siltstones that onlap older carbonate slope deposits at the NW margin of the Delaware Basin. This succession represents a lowstand qequence set comprised of lugher frequency sequences that were deposited in the basin during subaerial exposure and bypass of the adjacent carbonate shelf. Progradational sequence stacking patterns reflect changing position and character of the slope as it evolved from a relict, carbonate margin, to a constructional, siltstone-dominated slope. Lowstand fan systems tracts consist of sharp-based, laterally extensive, sand-prone basin floor deposits and large, sand-filled channels encased in siltstones on the slope. The abandonment phase of each sequence (lowstand wedge-transgressive systems tract) consists of basinward-thinning siltstones that drape the basin floor fans. The slope-tobasin distnbution of lithofacies is attributed to a three stage cycle of: 1) erosion, mass wasting, and sand bypass on the slope with concurrent deposition from sand-rich flows on the basin floor, 2) progressive backfilling of feeder channels with variable fill during waning stages of deposition, and 3) cessation of sand delivery to the basin and deposition of laterally-extensive siltstone wedges. Paleocurrents and channel distributions indicate SE-E sediment transport from the NW basin margin via closely spaced point sources.

Slope-to-basin variations in channel sue, geometry and fill are related to variations in the degree of bypass associated with channels and the timing of channel backfill. On the slope, major feeder channels are deeply incised into thick laminated siltstones, have simple margins, and are vertically stacked due to proximity of fixed point sources. The channel fills are highly variable in character, reflecting deposition from both lower and higherenergy flows during late-stage backfilling. At the toe of slope, sandstones occur in nested, multi-story channel complexes not confined by single, master erosion surfaces. Channel bases are commonly marked by lenticular, coarse-grained lags deposited from high-energy bypassing flows. Channel fills are complex, and indicate repeated episodes of erosion, bypass, and hackfii, with thick-bedded sandstones concentrated in channel axes and thin-bedded sandstones and siltstones preferentially preserved along channel margins. In down-fan, more aggradational settings, lags are absent. Channels are smaller, less complex, and simply filled with thick-bedded amalgamated sandstones. These channels are relatively short-lived features that were rapidly plugged by high-energy flows. In distal, predominantly nonchannelized areas of the basin floor, sandstones form laterally extensive sheets that are broadly lenticular as a result of minor erosion, depositional mounding, and compensational stacking patterns.

Depositional Setting Deep-water sandstones and siltstones of the Brushy Canyon Formation were deposited in the Delaware Basin of the Permian Basin Complex (West Texas and New Mexico) during early Guadalupian (Permian) time. During the Guadalupian, the deep-water portion of the basin (light gray area) had water depths on the order of 400-600 m (King, 1948) and was surrounded by extensive shallow-water shelves (dark blue areas) of the Northwest Shelf (north), Diablo Platform (west) and Central Basin Platform (east).

Basin Tectonics Development of the Permian Basin Complex was initiated in Mississippian to Early Pennsylvanian time in a foreland basin setting located to the north of the Marathon Fold Belt. Loading and convergence resulted in uplift of shelfal areas along high-angle reverse faults and subsidence in the basin. Thrust-loading in the Marathon Fold Belt peaked in the Late Pennsylvanian to Early Permian (early Wolfcamp) and was followed by isostatic adjustment that produced a wide-spread angular unconformity (mid Wolfcamp unconformity) along the basin margin (Ross, 1986). This unconformity locally cuts down into the Pre-Cambrian (King, 1965). Following the mid-Wolfcamp unconformity (Late Wolfcampian, Leonardian and Guadalupian time), the basin was characterized by tectonically stable shelf margins and gradually decreasing subsidence rates (from 3.7 cm/k.y. in the Wolfcampian to 0.8 cm/k.y. in the Guadalupian, Ye and Kerans, 1996).

Settina

-

I - - - - 5N Permian Paleolatitude modified from Wright, 1962; Fitchen, 1997 Figure 1. Basin setting and outcrop belt of the Brushy Canyon Formation, early Guadalupian (Permian).

II

I

Primary Measured Sections +

Paleocurrent Orientation Major Depositional Axis

ECS - El Capitan South GC - Guadalupe Canyon BM - Brushy Mesa PCC - Plane Crash Canyon PC - Popo Channel DM - Delaware Mountain CC - Colleen Canyon

Figure 2b. Paleogeographlc Interpretation of Brushy Canyon Outcrop Belt (Modified From: Zelt and Rossen, 1995)

[

atp-

wens Pear and m e spmng ~ormatNonr and LBonsidian mc*r undMde6

Figure 2a. Geologic map of West Texas and Brushy Canyon outcrop belt. From: Geologic Atlas of Texas: Van Horn-El Paso Sheet, 1967. Texas Bureau of Economic Geology

Figure 2% As shown on an insert from a geologic map of West Texas, the Brushy Canyon Fm. is exposed along the western escarpments of the Guadalupe and Delaware Mountains. These mountain ranges form a single structural block that was tilted gently eastward (3-10 degrees) and uplifted relative to the Salt Flat Graben located to the east, as a result of Late Cenozoic basin and range normal-faulting along NNW-trending normal faults (King, 1948). The northern limit of the Brushy Canyon occurs in the southern Guadalupe Mountains and marks the pinchout of the Brushy Canyon against the northwestern basin margin. The southern outcrop limit is structurally controlled. In the graben boundary zone, the outcrop belt is locally offset by NNWtrending normal faults with offsets of tens to several hundred meters. Structural complexity locally hampers lateral correlation of stratigraphic units in the northern Delaware Mountains (Guadalupe Pass area) and in the Delaware Mountains southeast of Bitterwell Mountain. Field analysis by Exxon has been concentrated in the northern 35 lan of the outcrop belt (Guadalupe Mountains National Park and 6 Bar Ranch areas).

Firmre 2b. The Brushv Canvon outcrov belt is intemreted torepresent an oblique-transkt from thk slope to baiin floor at the NW margin of the Delaware Basin. Paleocurrent indicators and channel distributions along the outcrop belt indicate siliciclastic sediment supply from the NW-W, via numerous closely-spaced (1-2 km)point sources. In the northern part of the outcrop belt (southern Guadalupe and northern Delaware mountains) the dominant direction of sediment transport is toward the SE (basinward and approximately normal to the interpreted trends of Leonardian-early Guadalupian carbonate shelf margins in this part of the basin). In the central part of the outcrop belt (central Delaware Mountains), paleocurrent indicate sediment transport to the E-SE. This variability is interpreted to reflect sediment input from both the northwest and western margins of the basin. As a result of variable flow directions, the NW-trending Brushy Canyon outcrop belt provides an oblique, dip-oriented profile into the basin in the north, and a more oblique, strike-oriented profile to the south.

Shelf-Basin Relationships Showing Position of 3rd-Order Senll~nceBoundaries oc ) Rustler - salad01

a

I 0

5km

1Okm

Delaware Mountains Figure 3. This figure illustrates a summary of the sequence stratigraphic framework for Upper Leonardian-Guadalupian strata of the Northwest Permian Basin A sequence stratigraphic framework has been developed for the Permian Basin strata based on the work of Silver and Todd (1969), Meissner (1972), Sarg and Lehmann (1986), Kerans and others (1992), Kerans and Fitchen (1995). In this diagram major, 3rd order sequence boundaries (composite sequence boundaries) are shown in red. Basinally-restricted deep-water siliciclastics (LST) were deposited during lowstands of relative sea level (LST) when shelfal areas were subaerially-exposed. Thin, laterally extensive sandstones on the shelf are interpreted as early

TST deposits. These sandstones typically overlie subaerial exposure sufaces, and are gradational upwards into overlying carbonate shelf deposits. TST and HST are dominated by shelf and shelf-margin carbonates that exhibit, respectively, retrogradational, and aggradational to progradationa1 vertical stacking patterns. Overall sequence stacking patterns of 3rd order sequences suggest that sequences contained within the Delaware Mountain Group formed within a 2nd order cycle composed of LST, TST, and HST dominated sequence sets. Within this second order cycle, the

carbonate highstand systems show an evolution from lowangle carbonate banks in the Early-Middle Guadalupian, to high angle reef margins in the Middle-Late Guadalupian (Kerans and Fitchen, 1996). The Brushy Canyon Formation and overlying Cheny Canyon Sandstone Tongue are interpreted, respectively, as the LSF and LSW systems tract for the basal Guadalupian third order (composite) sequence. The Brushy Canyon consists of up to 360 m of basinally-restricted sandstones and siltstones deposited in basin-floor and slope settings. At the basin margin, the

Brushy Canyon thins to pinchout by onlap onto a basinward-sloping submarine erosion surface (Harms and Pray, 1974) interpreted as a sequence boundary. Farther updip, in a shelf top setting, the base Brushy Canyon sequence boundary is correlated to a karsted subaerial exposure surface at the top of the Lower San Andres carbonate bank (Kerans and Fitchen, 1995). The transgressive-highstand systems tract for this sequence is represented by mixed clastic-carbonate, aggradational to progradational clinoforms of the Upper San Andres Formation.

NW+

GUADALUPE MTS. SHELF

SLOPE

SFN

SE

BASIN FLOOR

Figure 5 SC

-

DELAWARE MTS.

-30 Miles

EC

-Fig

6.t

GC

4t h Order

3rd Order

1 Upper B.C.

Middle B.C. Lower B. Upper Cutoff ~ i i eCutoff r Bone Spring Limestone

I

1 -I

LEGEND Lowstand Sandstones (deep water) &channels

-

Sheets Conglomerates

Lowstand Slope Siltstones

Carbonates

Lowstand Wedge Slope Siltstones Condensed Intervals

SSB Sequence Set Boundary SB

&

Sequence Boundary Slumped Zone

Sheit Sequence Stratigraphy from Korans and Fitchon, 19%

Figure 4. Schematic geologic cross section of the Brushy Canyon Fm. from the Guadalupe to Delaware Mountains illustrating the onlapping wedge-shaped geometry, the slope to basin floor variations in lithofacies and internal stratigraphy. Also shown are the general locations of photographs shown in figures 5 and 6. Basinally-restricted, deep-water sandstones and siltstones of the Brushy Canyon Fm. are Early Guadalupian in age, and are interpreted as a third order, lowstand sequence set that was deposited in the Delaware Basin during subaerial exposure and bypass of the adjacent, carbonate shelf. On the slope and basin floor, the base of the Brushy Canyon Fm. is a basinward-sloping submarine erosion surface that truncates older (Leonardian-early Guadalupian) carbonate rocks of shelf margin and slope facies. This surface is cor-

related updip on the shelf to a subaerial exposure surface developed at the top of the Lower San Andres carbonate bank margin (Keraus and Fitchen, 1995). In basin floor areas, the Brushy Canyon can he subdivided into three, laterally persistent sand-prone units separated by thinner, laterally persistent siltstones which are interpreted as high frequency (4th order) sequences (informal lower, middle, upper Brushy Canyon members). The lowstand

fan systems tract (LSF) of each sequence consists of sharpbased, laterally-persistent, sandstones on the basin floor, and of large, sand-tilled channels encased in siltstones on the slope. The abandonment phase of each lowstand systems tract (lowstand wedge-transgressive systems tract) consists of basinward-thinning siltstones that drape the basin floor fans. Basin floor deposits are best represented in the lower Brushy Canyon member, whereas the transition from slope to basin floor is best expressed in the upper

Brushy Canyon member. The overall progradational stacking pattern of Brushy Canyon high frequency sequences suggests evolution of the slope from a relict, carbonate slope that was primarily a site of sediment bypass in early Brushy Canyon time, to a more constructional, siltstonedominated slope in late Brushy Canyon time.

DELAWARE MTS.

1

Figure 5. Oblique aerial view to NW showing slope to basin floor transition in Brushy Canyon outcrops of the Guadalupe and Delaware mountains.

This photo provides a vlew toward the basin margin from the palm basin-floor. The base of the Brushy Canyon (heavy red line) consists of a basin margin submarine erosion surface and correlative conformity on the basin floor that is interpreted as a LST sequence set boundary (SSB). The blue line, near the top of the Delaware Mountains, marks the approximate position of the Brushy Canyon "genetic top" (CSM Top Brushy Canyon) of Gardner and Sonnenfeld (1996). In the basin margin area (Guadalupe Mountains), the Brushy Canyon is dominantly composed

of laminated siltstones that are interpreted as slope deposits. In the Delaware Mountains (right) the Brushy Canyon is dominated by 3 laterally-extensive sandstone packages (informal Lower, Middle and Upper Brushy Canyon members) that are interpreted as basin floor deposits (4th order LSF). Thinning of the Brushy Canyon toward the basin margin (from 370 m on the right side of the photo to 100 m on the left side) occurs by progressive onlap onto the basal SSB, and the Brushy pinches out entirely a few km to the north of the area shown in this

photo. The 4th order LST intervah can be further subdxvided into higher order units as is evident within the Lower Member in this photo. Four or five resistive sandstone bodies capped by sandstone-poor intemals can be traced for several kilometers from south to north. Although not obvious from this view, the Upper Member can be subdivided into a similar number of 5th order units. Tracing higher order units in the Middle Member is more difficult because of a lack of prominent, laterally extensive siltstone intemals and a high degree of amalgamation of sandstone

units. Based on our correlations, the Lower Brushy Member onlaps the SSB (or facies changes into slope siltstones) in the area below El Capitan. The top of the Middle Member extends farther updip and is correlated into Bone Canyon of the western escarpment, Guadalupe Mountains. The hulk of the Brushy Canyon Fm. present on the Western Escarpment is interpreted to be stratigraphically equivalent to the Upper Brushy Member of the Delaware Mountains.

I Basin-Floor Expression of Brushy

ary (SB), 4th Order rface, 3rd Order urface, 4th Order -mi

Figure 6. Stratigraphic succession of Brushy Canyon in basin-floor position (view to NE from Lookout Knob) Stratigraphic Hierarchy: On the basin floor, the base Brushy Canyon sequence set boundary is a relatively conformable surface underlain by the Pipeline Shale and Upper Cutoff Formation. The Lower, Middle and Upper Brushy Canyon Members, interpreted as 4th order sequences within the Brushy, form three distinctive, topographic mesa or benches that are laterally persistent across the outcrop belt. Each member contains a lower sandprone unit (100-150 m thick) interpreted as a LSF that is capped by a thinner (up to 15 m thick) laterally extensive siltstone internal (interpreted as a LSW). The "40 ft. Siltstone" that separates the Middle and Upper Brushy Canyon Members can be traced with confidence from this

area to Guadalupe Canyon, located some 20 k m to the north. The 4th order LST intervals can be further divided into higher order units that are important for local correlation and potentially for analysis of vertical stacking patterns. Higher order units are most apparent within the Lower Member which can be subdivided into five laterally persistent sandstone ledges that can be traced for several kilometers laterally. Although not obvious from this view, the Upper Member can be subdivided into a similar number of units. Higher order subdivision of the the Middle Member is more d i i c u l t due to the high degree of channelization and local lack of laterally persistent siltstones.

Vertical Stacking Patterns: In this position, the three Brushy Canyon Members show a distinct vertical progression in sand body geometry, channel abundance, and channel geometry. The Lower Brushy Member is dominated by sheet-like, tabular sandstone bodies or packets, that locally contain small-scale sand-filled channels with simple erosional margins. In the Middle Brushy Member, simple sand-filled channels are larger and more abundant.

Although not well exposed in this view, the Upper Member is characterized by very large, deeply incised, multi-story channel complexes with amalgamated sandstone fills up to 1 km wide (e.g. Buena Vista locality indicated on photo). These channel complexes are quite complex and record multiple episodes of channel cutting, bypass and back-filling. The Brushy Canyon stratigraphic hierarchy and vertical stacking patterns are reviewed schematically in figure 7.

Zelt &

King (1948)

Rossen(1995)

t SEQUENCE STRATIGRAPHY 8 SaLa,SQ ??g 4e m,

pk

HIGHER ORDER SURFACES, DEPOSITS

o

iRRY CANY :ORMAT

Channel Fill Assemblages

\ ,

BRUSHY CANYON Beds I Bedsets

Y

I

I

PlPLELlNE SHALE

?

V A

Abandonment, Drape Surfaces I Intervals Erosional Surfaces, Sequence Boundaries

* the number and stratigraphic position of 5th order packages shown is only a schematic and not meant to depict the actual internal stratigraphy of any LSW TST (Lowstand Wedge, Lowstand Sytems Tract member of the Brushy Canyon Formation and Transaressive Svstems Tracts undifferentiated)

LSF I LST (Lowstand Fan, Lowstand Sytems Tract)

-

-

Figure 7. This diagram relates the lithostratigraphy and sequence stratigraphy of the lower Delaware Mountain Group, emphasizing a hierarchy of bounding surfaces and schematically depicts the large scale, apparently progradational stacking patterns discussed on previous pages. Stratigraphic Subdivisions of the Brushy Canyon Formation. The Brushy Canyon Fm. represents a 3rd order LST sequence set that is bound above and below by major unconformities or their correlative conformities, and can be correlated throughout the Delaware Basin. In the outcrop belt, this sequence set consists of three 4th order stratigraphic packages that are bound by sharp, locally erosional contacts and can be correlated throughout most of the Delaware Mountains and a portion of the Guadalupe Mountains (30-40 km). Surfaces of abandonment separate LST fan (LSF) dominated intervals from LST wedge (LSW) - TST dominated intervals. The sandstone-rich por-

tions of these units contain a number of 5th order units that are also bound by erosional surfaces, contain internal abandonment surfaces, and can be correlated for distances up to 20 km within the outcrop belt. The 5th order packages are built of higher order depositional units that include channel fill assemblages, bed sets and beds that generally do not have long correlation lengths, but can be subdivided in the same manner.

3rd Order Stacking Patterns. The stacking patterns, lithofacies and channel types are distinct between the LSF intervals of the 4th order units and the diagram depicts the large scale, apparently progradational stacking of 4th order units seen in the Delaware Mountains. In general, the Lower Brushy Canyon is dominated by sheet-like, tabular sandstone bodies. Channels occur within extensive sandstone "packets" and are often genetically associated with adjacent sandstone sheets. Channel types and lithofacies are consistent with medial-outer fan depositional environments. The Middle Member is seen as primarily a mix of laterally extensive sandstones and relatively large channels filled with massive sandstones. The channels have relatively simple, erosional margins and genetic associations between channel and inter-channel strata are not obvious.

In general, the channel types and lithofacies are consistent with proximal-medial fan depositional environments. By contrast, the Upper Member is characterized by very large, deeply incised, multi-story channel complexes up to lkm wide separated mainly by unrelated, inter-channel strata. The fill of these complexes record multiple episodes of channel cutting and filling and evidence for prolonged periods of bypass. The channel types and lithofacies are consistent with middle-lower slope depositional environments. These stacking patterns may indicate: a) changes in the orientation or position of depositional axes of systems through time, b) progradation of systems through time, c) a change in the style and character of depositional systems through time, or d) some combination of these processes.

Down-Slope Trends in the Erosion, Transmission and Deposition of S1 mt ' Ti ' idity Currents

'hrbidites, > 90 % of the Brushy Canyon Fm. Bedload Deposits Median grain size: > Coarse Sand

Stratification: 1. plane parallel beds and laminae;

2. tabular cross beddmg; 3. trough cross beddmg; 4. isolated (starved) bedfonns.

Key Points: These deposits are defined here to primarily consist of particles that travelled as bedload some minimum distance before deposition that was at least equal to the thickness of the transporting turbidity current. Since maximum bedload velocities are only about 114 of the average current velocity, with time this coarser-grained material separates from the suspended sediment and the current itself. These relatively thin deposits, interpreted as lags, are up dip equivalents to thicker sandstones that were deposited from suspension from relatively longlived turbidity currents.

Suspension Deposits Median grain size: < Medium Sand Shurtfication: 1. structureless beds (may be graded); 2. climbing dune stratification (trough cross bedding); 3. ripple stratification; 4. plane parallel laminae.

Key Points: Sandy turbidites. Climbing dunes and ripples document the movement of sediment as bedload after it has settled out of a turbidity current from suspension. These deposits are still considered suspension deposits because the distance the sediment moves as bedload is very small relative to its length of transport as suspended load. The

supercritical climb of both types of bedforms constrains the bedload-transport distance to less than one bedform length, a distance of less than 3 m. Many of the fusulinids within the sandy turbidites can be interpreted to have been moved into sites of deposition as bedload. The intermingling of this bedload with the suspended load requires that it travelled to the site with approximately the same velocity. This suggests that the fusulinids fell out of suspension a relatively short distance up dip from the site. Otherwise, the slower moving bedload would not arrive at the site of deposition until after most of the sand bed had already accumulated.

L

"

-.

INITIATION OF TURBIDITY CURREh BY FAILURE OR UNDERFLOW

I

FLOW DECELERATION LEADS TO CURRENTS THAT ARE "OVERCHARGED" WlTH SUSPENDED SEDIMENT, DRMNG FLOWS CONTINUE TO DECELERATE DUE DEPOSITION TO DROPS IN THEIR EXCESS DENSITY THAT ARE PARTIALLY ASSOCIATED WlTH THE DEPOSITION OF PREVIOUSLY SUSPENDED SEDIMENT

Silty turbidites. Progradation of the submarine slope to the Delaware Basin throughout deposition of the Brushy Canyon Fm. is primarily the result of the deposition of thick, wedge-shaped packages of silty turbidites. These thin-bedded turbidites came from slow-moving currents that began depositing sediment at the time of their initiation. These currents are different than those that accelerated down some portion of the slope, cutting channels and transporting sand all the way to the basin floor.

Debrites < 5 % of the Brushy Canyon hm. Fabrics of these deposits range from frameworks of gravel with sand-filled pore spaces to sandstones with a small number of out-sized clasts. Pebbles, cobbles and boulders in these deposits are either limestones from underlying formations or intraformational rip-up clasts.

Hemipela ites, < 5 % of the Brushy Canyon m.

8

These mudstones are made up of particles from either a hypopycnal plume or a wind-blown source. The deposits are typically enriched in total organic carbon. Centimeter-thick volcanic ashes are present.

1

DEPOSIT TENDENCY:

Erosion by Head of Current

+

-

-

Erosion (L Deposrt~on by Body of Current

+

,

Bypass 8 Deposition b Tail of Zurrent

+-

.

Figure 8b. Sediment is constantly being exchanged between the bed and an overriding turbidity current so any modification of the surface by the current is always equal to the sum of a depositional and erosional component. A turbidity current can be divided into three parts, a head, a body and a tail. Differences in properties of the flow from the head to the tail of a current set the patterns of erosion and deposition associated with its passage over any particular point on the bed. The heads of turbidity currents always have a tendency to erode the substrate, because the arrival of the head is always associated with an acceleration. The bodies of turbidity currents carry most of the suspended sediment in the flow. Therefore, conditions in the body determine whether at a point the current primarily is eroding the bed, depositing sediment on the bed, or carrying it further down dip. If sediment carried in the body is bypassing a section of

the bed, the only possible suspension deposit at that point would come from the tail. Packages of thinly bedded, relatively fine-grained turbidites can be seen directly on top of many significant erosional surfaces. These deposits can be interpreted either as sedimentation associated with a relative shutdown of the sediment delivery system or as the deposits of the tails of bypassing turbidity currents. The two interpretations forecast a very different location for the time-equivalent sands. In the shut-down scenario any sand is expected to be trapped up dip of these positions, while in the case of bypass, sand is expected further out into the basin.

Generic Turbidite Profile --. I---

: I:: 11::

Complete Sediment BypaswTransmission: with no additional erosion

Ineamplete Sediment Bypass, Type 1:Thin, lenticular, coarse-grained beds, interpreted as lags of bedload material.

Incomplete Sediment Bypass, Type 2: Thin, onlapping, fine-grained beds, interpreted as deposits of turbidity-current tails.

111

'

I-----

I

I

IV

Relative Downslope Distance Figure 9b. A channel complex records a history of cutting and filling associated with a succession of turbidity currents. The changes through time observed in any vertical section through a channel complex are the consequence of spatial changes in the position of that channel cross-section relative to the runout of the characteristic turbidity current. During Phase I this turbidity current is eroding the substrate in this position and depositing all of its sediment load further down dip. During Phase 11, this channel cross-section is located where currents are just beginning to deposit sediment. During Phase III the cross-section and the "sweet spot" of turbidity-current deposition are coincident. During Phase N the cross-section is located down dip of almost all turhidity current deposition.

Deposition of thielS, laterally persistent beds that d a p the margins ofthe heerosional containec Variable degrees of emdon can be associated with the bases of these beds.

4-

siltstone --+ drape

Substantial reduction in the quantity and caliber of the sediment moving down a channel associated with change in updip conditions (e.g., relative sea-level rise or channel avulsion).

Figure 9a. Conceptual model for construction of a channel complex.

Approximate envelopes for each of these phases are drawn above on the profile for the generic turbidite. Changes through time in the character of the runout of the effective turhidity current are primarily controlled by variation in the amount of sediment available, in the caliber of this sediment and in the long profile of the system.

1

Slope to Basin Variations in Channel and Sandbody Archib--b. .re, Brushy Canyon Formatin-, Delaware Basin Shelf n

Basin Floor

=\

Figure 10. Schematic illustration of slope to basin transect planned for conference. Slope to basin variations in channel size, geometry and fill are interpreted primarily to be related to systematic, down-fan changes in the degree of erosion, the degree of sediment bypass, and the timing of channel filling.

Day 3

Day 4 Proximal Basin Floor ,,-:-..res 4.2-4.4'

1

~:!s*&*e:~y~&;

Day 4"4g+@s$$ &&&* Medial Basin Floo (Figures 4.F * 8)

Distal Basin Floor (Figures 5.1-5.3)

Submarine canyons consist of erosional features, up to 100 m deep and 1 km wide, incised into older shelf margin carbonates. Fills are locally conglomeratic and predominantly composed of amalgamated, channelized, thick-hedded sandstones. On the middle to lower slope, 10-50 m deep, vertically-stacked slope channels are incised into thick, basinward-thinning wedges of laminated siltstones. These channels are characterized by simple to compound channel margins, and by variable fills that range from thick-bedded, amalgamated sandstones, to thin-bedded, non-amalgamated sandstones. Channel fill variability is attributed to long histories of sediment bypass followed by relatively late-stage filling compared to channels on the basin floor. Vertically-stacking of channels is locally controlled by slump-scar topography and reflects p r o x i ~ t yto up-dip feeder canyons.

At the toe-of-slope, the decrease in depositional gradient leads to development of broad, multi-story channel complexes that are not confined by master erosion surfaces. Major channel surfaces are marked by lenticular, coarsegrained lag deposits that were deposited by bedload deposition from by-passing, high-concentration flows. Axes of channels are dominated by amalgamated, thick-bedded turbidites, whereas thin-bedded sandstones and siltstones are preferentially preserved along the channel margins. Multiple erosion surfaces separate the channel axis facies from the thin-bedded channel margins. Complex patterns of channel fill record overall channel aggradation through repeated episodes of erosion, sediment bypass and channel filling.

On the basin floor, channels are less deeply incised, and typically have simple margins. Coarse-grained lag deposits are less common, and channels typically stack in compensational, or laterally-offset stacking patterns. In proximal basin floor areas, channels are moderate in size and are typically filled from axis to margin by thick-bedded, amalgamated turbidites. These channels are interpreted as relatively short-lived features plugged by rapid deposition from high-concentration flows. In medial basin floor areas, channels are less incised and channel fills consist of highly aggradational successions of massive or dune cross-stratified sandstones. At the transition from confined to unconfined portions of the fan, channels consist of vertically-stacked, low-relief erosion surfaces that pass laterally (away from the channel axis) into medium- to thickbedded, amalgamated to non-amalgamated, massive sandstones that form laterally extensive, but broadly lenticular sheets.

The distal basin floor is predominantly composed of laterally-extensive sandstone sheets composed of medium- to thick-bedded, amalgamated to non-amalgamated massive turbidites. Beds are typically broadly lenticular and stack compensationally. Channels exhibiting obvious erosional confinement are rare and axes of deposition in this setting are represented by zones of vertically-stacked, amalgamated thick-bedded turbidites that are flanked laterally by medium-bedded, semi-amalgamated turbidites. These features reflect rapid suspension deposition in an unconfined setting from predominantly high-concentration flows.

ieneralized Three Stage Evolution of Lowstand Systems Tracts, Brushy Can--- n Formation I. MAIN PHASE LOWSTAND FAN

I

II. LATE-STAGE LOWSTAND FAN

TIME INCREASING

Figure 11. Interpreted evolution of Brushy Canyon lowstand systems during 4th order lowstand of relative sea level. An understanding of the relative timing of sand-prone deposition on the basin floor versus slope during a cycle of sea level change explains many of the variations from slope to basin floor in channel architecture that were described in the previous figure. During Time I (Main Phase of Lowstand Fan), falling base level and a lack of accommodation on the shelf result in high rates of sediment supply to the basin floor via suhmarine canyons. Slope channels are primarily zones of bypass and the basin floor is the main site of deposition for high-energy, high-concentration, sediment gravity flows. As a result of rapid fan aggradation, the time duration between channel cutting on the basin floor and channel filling is interpreted to be relatively short. Short phases of

channel bypass followed by back-filling from high concentration flows result in a predominance on the basin floor of shallowly incised channels that are simply filled with thickbedded, amalgamated turbidites. During T i e II (Late Stage of Lowstand Fan), a slow relative sea level rise results in increased accommodation on the upper slope and outer shelf. Sediment flux to the basin floor is reduced and deposition is focused in slope

channels that previously served as bypass corridors to the basin. Channel fills may reflect deposition from a variety of flow types (both high and low concentration flows) depending on the "caliber" or importance of the point source as a sediment contributor, and the character of flows delivered to the slope at the time of back-filling. During T i e 111(Lowstand Wedge), higher rates of relative sea level rise and increased accommodation on the

shelf result in cessation of sand delivery to the basin and abandonment of both lowstand fan and slope channel systems. Deposition at the basin margin from dilute, low-density tubidity currents results in development of thick wedges of laminated siltstone that thin basinward. This stage represents the constmction, or out-building of the slope during Bmshy Canyon time. Thin, organic-rich siltstones containing volcanic ashheds represent deposition during times of condensed sedimentation.

Comparison of Interpreted Paleogeography for Lower and Upper Brushy Canyon Members -

Schematic Paleogeographic Map Lower Brushy Canyon Formation

~

Schematic Paleogeographic Map Upper Brushy Canyon Formation

PROXIMAL CHANNELIZED FA BRUSHY MESA (EM)

CHANNELTO SHEET TRANSITION: COLLEEN CANYON (CC)

I

SHEET COMPLEXES: CORDONIZ CANYON ma

S C u E t

,

APPROXIMATE LOCATION OF OUTCROP-'I

Figure 12. Comparison of interpreted paleogeography for Lower and Upper Members of the Brushy Canyon Formation illustrating the progradation of depostional systems. For each member the positions of slope and basin floor environments are interpreted to have shifted progressively basinward through time. The approximate locations of the outcrop belts are shown as red dashed lines. The position of the paleo-slope is interpreted to have progressively built basinward during deposition of the Brushy Canyon sequence set. The position of the slope for the Lower Brushy Canyon Member was inherited from the relict CutoffBone Springs carbonate slope seen in the Guadalupe and Diablo Mountains. During the remainder of Brushy Canyon deposition the slope was "constructional" and dominated by basinward tapering, siltstone wedges.

The siltstone slope facies that dominates the basin margin area extends further southward into the Delaware Mountains for the upper Brushy member than for that of the middle member reflecting this overall slope progradation. Additionally, the stacking patterns, lithofacies and channel types are distinct between the sandstone-rich, LSF intervals of the 4th order units seen in the Delaware Mountains. In general, the Lower Brushy Canyon is domi-

nated by channel types and lithofacies consistent with medial-outer fan depositional environments. The middle member is dominated by channel types and lithofacies consistent with proximal-medial fan depositional environments. By contrast, channel types and lithofacies within the upper member are consistent with middle-lower slope depositional environments. Based on these observations general paleogeographic maps have been drawn for the upper and

lower members of the Brushy Canyon Formation and are shown above. However, the limited depositional dip perspective of the outcrop belt, and a lack of understanding of how and where these 4th order LST terminate within the basin hampers the interpretation of the stacking patterns.

Figure 1.1. Topographic map showing an approximate outline of the Brushy Canyon outcrop belt, and locations of sites that will be visited on this trip. Upper Brushy Canyon sites are shown in green, Lower Brushy Canyon sites are shown in orange. Also shown are general paleocurrent directions and the approximate position of the toe-of-slope for each member of the Brushy Canyon Formation.

0jubmarine Canyon North Shumar

mlles

i5 North

Paleageography This palwgwgraphic reconstruction for the Upper Brushy Canyon shows that the noahem 20 lan of the outcrop belt was deposited in a slope to roe-of-slope setring. This slope was approximately 15 km wide, and had basin-ward dips of 2 degrees (assuming water dept!s of 4.50-600 m). Much of the slope was siltstone-prom and composed of thick basinward-thinning wedges of laminated siltstones interpreted as the deposits of dilute, fine-grainedturbidity currents*

Sediment Transport Sands were transported across this cofistructionalsiltstone slope, from the NW basin m a i n towards the SE-E, via numerous closely-spaced point sources or sediment transport pathways The outcrop belt intersects these point sources in up-dip positions to the n a t h and progressively mare down-dip positians to the south.

Charmel Architecture Thee main archtectural styles are recognized from up-dip to down-dip positions along these sediment transport pathways: 1) Upper slope areas are characterized by submarine canyons, incised into older, shelf-margin carbonates. These canyons are filled with a mix of siltstones, and large, sand-filled channels. The canyons typiedly broaden, and shallow out down-slope into more aggradational slope ssttings. 2) Middle to lower slope areas, down-dip of canyons, are characterized by sand-filled slope channels incised into thick laminated siltstones. These slope channels are typically vertically-stacked due to the focusing effect of up-dip feeder canyons. 3) In toeof-slope areas, the decrease in gradient and loss of channel confine-

ment results in a transition from vertically-stacked slope channels, to bmad, nested multi-story channel complexes. These toe-of-slope channel complexes contain common caarse-grained lags and exhibit complex fill patterns that indicate repeated episbdes of erosion, sedimedt bypass, and channel back-filling.

Figure 1.2. Schematic paleogeographic map of Upper Brushy Canyon Formation. This paleogeographic map highlights the main slope environments (submarine canyons, slope channel complexes, and toe-of-slope channel complexes) that will be the focus of the first three days of the field conference. Day 1 will focus on submarine canyon fills and slope channel complexes in middle to upper slope settings. Day 2 (Guadalupe Canyon) will focus on vertically-stacked, slope channel complexes deposited in a middle slope environment. Day 3 (Buena Vista) will be spent investigating characteristics of channel complexes deposited in lower slope (toe-of-slope) environments.

Day I . Basin Margin Onlap Area: Su -

-

Figure 1.3. Panoramic photograph and sketch of western escarpment, Guadalupe Mountains showing the northern 10 km of Brushy Canyon outcrop belt in the most proximal area near the NW margin of Delaware Basin. Detailed photographs of the area shown on following pages are referenced with white circles. A geologic map of the area is shown on the next page. The Brushy Canyon Sequence Set Boundary In the basin margin area, the Brushy Canyon thins towaru the north (from 400 m beneath El Capitan to ultimate pinchout just north of Sbumard Peak) by onlap onto a relict carbonate shelf margin complex of Leonardian-Early Guadalupian age (Victoria Peak, Bone Spring and Cutoff formations). The onlap surface is a basinward-sloping

Depositional Setting submarine erosion surface, that is correlative on the shelt with a karsted, subaerial exposure surface. To the south, in basin floor areas, it is a sharp, but relatively conformable contact with the Pipeline Shale.

In this area, the Brushy Canyon is largely siltstone-prone, reflecting deposition in a slope setting. Sandstones are confined within large erosional channels (10-50 m deep) that are vertically-stacked to form laterally distinct "fairways" or point sources into the basin. On the upper slope, these sand-filled channels are confined within submarine canyons up to 1 km in width that are incised into

the Victoria Peak carbonate bank. Downdip, on the middle to lower slope, these canyons open up and feed sand-

stone-filled slope channels that are incised into thick laminated siltstones. The vertical stacking of these slope channels reflects the focusing effect of the updip feeder canyons.

Geologic Map of the Bone Springs Area of the Western Escarpment of the Guadalupe ~ o u n t a i n s Modified from King (19i8)with information from Rossen (1 985),Harris (1 982),Franseen (1 989), Fitchen and Kerans (1995), Gardner et al. (1W6), Rossen et al. (1998)

4

0

0

El Capitan X 8078 Guadalupe , Peak

0

North

1000

2000

1 . . . . . . . . . 1 . . . . . . . . . I

Bell Canyon Formation

A

Brushy Canyon S

base

U.Cutoff SI

South Wells Member

base

Lower Victorio Peak Fm.

U.Vic.Pk. SI

youngest -

Figure 1.4. Geologic Map of the West Face of the Guadalupe Mountains adapted from King (1948) emphasizing stratigraphy of Brushy Canyon Formation upper slope systems.

--

4

I

-

LZ'

oldest

Shumard Canyon System El Capitan North System El Capitan South System Bone Canyon System

Paleo-current lndlcators Rossen et al. 1998

-----

3rd Order Sequence Boundary 3rd Order Sequence Boundary Approx~mate CSM Brushy Canyon Genetlc Top Approx~mate

Brushy Canyon Formation Siltstones (-org. rich] Sandstones, Conglomerates

Figure 1.5a. Basal, conglomeratic fill of the "Bone" paleo submarine canyon, Lower-Middle (?) Brushy Canyon Fm., Bone Canyon, Guadalupe Mountains. The "Bone" submarine canyon is approximately 75 m deep and 650900 m wide (see Fiaure 1.4). and is cut into the underlvina Cutoff and Bone S~rinaformations. The canvon trends SE and is exposed ii'an interpreted slope posiion: The basal 25 m of'canyon fill consists i f &&ateclast conglomerates (0.5-7.5 m thick) and interbedded, thinner, stratified sandstones. The conglomerates contain pebble to boulder-sized clasts (up to 4 m in length) and are interpreted as debris-flow deposits. Clasts within the conglomerates were locally derived from carbonate shelf-margin and slope deposits of the underlying Cutoff, Victorio Peak and Bone Spring formations.

Base of Brushy Canyon Cufoff Fm.

-

Conglomerate Limestone turbidites Siltstone

Figure 1.5~.Measured section of basal 75m of Bmshy Canyon Fm. that fills the "Bone" submarine canyon (from Rossen, 1985). Fill of the "Bone" submarine canyon is variable, and is subdivided into 3 channel fill associations (units 1-3) originally mapped by King in 1948 (see Figure 1.4). The overall variability of canyon fill is interpreted to reflect variable flow types during late-stage canyon filling.

Unit 2 has a channelized base and consists of medium to thick-bedded, sandy, peloidal-skeletal grainstones that commonly exhibit Bouma turbidite subdivisions (i.e., graded Ta, Tab, and Tbc beds). This unit reflects basinward transport of carbonate material derived from contemporaneous, shallow-marine environments existing at the heads of canyons.

Unit 1 consists of carbonate-clast con.domerates and interbedded sandstones. Successive conglomerateinits exhibit an overall thinning and fining-upward stacking pattern. Sedimentary structures in intervening sandstone units (upper plane-bed laminations, planar cross-bedding, small-scale channelization, and thin-bedded classical turbidites) suggest deposition by both high-concentration, and lowconcentration turbidity currents.

Unit 3 consists of channelized, medium- to thick-bedded, massive sandstones (interpreted channel axis facies) that interfinger laterally with thick intervals of rippled sandstones (interpreted channel margin facies).

Figure 1.5b. Cabonate clast conglomerates, basal Brushy Canyon, Bone Canyon. The Brushy Canyon conglomerates in Bone Canyon consist of framework-supported pebble to boulder-sizedclasts in a matrix of very fine-grained, silty sandstone. The conglomerates are interpreted as debrites based on: 1) chaotic clast orientations or weak alignment of clasts parallel to bedding, 2) massive ungraded character, 3) overall non-erosional basal contacts, and 4) local protrusion of clasts above the tops of beds. The conglomerates reflect successive failures of the lithified carbonate basin margin that represent headward erosion of the "Bone" submarine canyon. As shown on Figure 1.4, the NE canyon margin occurs 300 m (1000 ft) to the north of Bone Canyon where the entire, 75 m thick, basal Bmshy Canyon succession pinches out by onlap (sidelap) onto the base Brushy Canyon sequence boundary. The SW canyon margin is not as well defined; however, thickness patterns suggest that the canyon margin occurs just SW of Bone Canyon. In a SE direction (toward the basin), the breakup of the amalgamated Bone Canyon channel fills (units #1-3) into channelized lenses, separated by siltstones, is interpreted to reflect broadening and shallowing of the Bone submarine canyon, and deposition in an increasingly aggradational slope environment.

Upper Slope Submarine Canyon and Middle Slope Channel Systems Upper Brushv Canvan. Shirttail to Shumard Canvons Fiaure 1.6a. "Shumard" submarine canvon. Shirttail Canvon

shelf-margin carbonates of the Cutoff and Victorio Peak formations. The NE canyon margin defines the northern (up-dip) extent of the Brushy Canyon outcrop belt (Brushy Canyon "pinchout"). The lower 213 of the canyon fill consists of channelized, amalgamated, thick-bedded sandstones. Siltstones (forming recessive slopes) are locally preserved along the canyon margins. The upper 113 of the canyon fill consists of siltstones and small, sand-filled channels containing abundant carbonate

canyon. As the ~ h u m i r dpaleo-canion is tracked downdip, the canyon broadens and opens up. Amalgamated, channelized sandstones of the canyon axis become less amalgamated and separate to form the vertically-stacked sand-filled slope channels exposed in present-day Shumard Canyon. In this obliquedip view, the channels are 10-50 m deep and are incised into laminated siltstones. The sandstone fills of successively younger channels are thicker-bedded, more amalgamated, and

more clast rich. This stacking pattern may be local to this feeder since similar vertical variations are not well developed in other stacked slope channel complexes of similar age.

Figure 1 . 6 ~ .Marginal, oblique dip-view of lower slope channel, Shumard Canyon. The fill at the margin of this channel consists of a thick (25 m) suc-

cession of thin-bedded, planar and ripple-laminated sandstones (Bouma Tb & Tc turbidites) and interbedded siltstones. Toward the channel axis, thin-bedded low-concentration turbidites are replaced by increasing proportions of thicker-bedded, Ta sandstones. Note the channel base is a simple erosion surface incised into laminated siltstones.

Figure 1.7. Upper Brushy Canyon slope siltstones of the El Capitan south area. This area is representative of the Brushy Canyon "constructional" slope environments. An approximately 300m thick interval of alternating light and dark colored siltstone is capped by a thick, channelized sandstone body.

1.7a. Photograph showing thick slope siltstones that are characteristic of areas located between slope channel fairways. Siltstones are composed of two main lithofacies: 1) light gray, medium to coarse-grained, laminated siltstones (1.7h) and 2) dark gray, fine-grained, organic-rich siltstones (1.7~).High-relief erosion surfaces, cut into siltstones and draped by laminated siltstones (see arrows), are common in some slope areas. Some of these surfaces are interpreted as evacuated slump scars. 1.7b. Example of light gray, laminated siltstones. Mm-scale, graded laminations are interpreted as deposits of dilute, fine-grained turbidity currents. 1.7~.Example of dark-gray, organic-rich siltstones which serve as excellent marker horizons within the Brushy Canyon Fm. These siltstones have up to 2% TOC (marine algal kerogen type) and are interpreted as relatively condensed, hemipelagic deposits.

Figure 1.7a. Example from El Capitan area of thick slope siltstones that are characteristic of areas located between slope channel fairways.

Figure 1.7b. Example of light gray, laminated siltstones. r i c h wl I Figure 1.7~.Example of dark-@ay,~ ~ ~ ~ n i c -siltstorl.=~ serve as excellent marker horizons within the Brushy Canyon Fm.

PALEOFLOW OUTSIDE NORTHERN CHANNEL MARGIN RIPPLE MARKS IN THIN-BEDDED NRBIDITES IN OVERBANK NORTH OF CHANNEL INDICATE FLOW OBLIQUELY TOWARD CHANNEL

MEAN = 112

area explained in more detail on next page

CHANNEL MARGIN STRIKE MEASUREMENT

FLOW TOWARD CHANNEL AXIS

l 3 PALEOFLOW ALONG SOUTHERN CHANNEL MARGIN

PALEOFLOW OUTSIDE SOUTHERN CHANNEL MARGIN RIPPLE MARKS IN THlh-BEDDED TLRBlDlTES SOLTH OF ChANNE. INDICATE FLOW AWAY FROM CHANNEL

CHANNEL TREND

PALEOFLOW ALONG NORTHERN CHANNEL MARGIN RIPPLE MARKS IN THIN-BEDDED TURBlDlTES INDICATE

MEAN = 139

RIPPLE MARC3 Ih Th h-BEDDED TJRBlDlTES NDICATE FLOW OBLIQUELY AWAY FROM CHANNEL AXIS

...

111

Figure 2.1. Panoramic photograph, Upper Brushy Canyon Frn, Guadalupe Canyon area. The photograph shows approximately 150 m (500 ft) of section. The outcrop is oriented perpendicular to channel margins which trend E-SE.Paleocurrent measurements are from the 100 ft. channel near the top of the section Key features visible in this outcrop include: 1) Vertically-stacked sand-prone channel fills encased in siltstones: Sandstone channel fills #1-5 (oldest to youngest) are contained within master erosion surfaces (red lines) that are incised into siltstones and thin-bedded turbidites. The master erosion surfaces typically occur 1 to several meters below the base of the onlapping sandstone fill. This relationship is documented in more detail on the following page.

2) Large, channel-form erosion surfaces incised into sandstones and are overlain by thick, siltstone-prone intervals. Sandstone channel fills #2 and #3 are truncated by highrelief, channel-form erosion surfaces that are filled with draping and/or onlapping siltstones and thin-bedded sand-

stones. The thin-bedded, fine-grained channel fills may represent deposition from the "tails" of bypassing flows, or more likely reflect an episode of abandonment after channel erosion.

3) Channel dimensions: Large, channel-form erosion surfaces are 15-30 m deep, and up to 500 m wide. The most completely exposed channel has a widwdepth ratio of 16.

4) Sandstone channel fills: Channel fill styles are variable (see next page). Dominant fill types consist of non-amalgamated, medium- to thick-bedded, internally massive sandstones with planar, non-erosional to moderately erosional bases. Sandstones are typically laterally extensive across channels, but thin gradually towards channel margins. Channel margins are typically overlain by "drapes" up to

several meters thick, of inclined, thin-bedded classical turbidites and siltstones that mantle and gradually onlap the basal erosion surfaces. A crude, thickening-upward bedding trend is observed in channel #4 (the 100' channel). This bedding trend may reflect decreasing capacity of flows to transmit sediment farther basinward as channel infilling progressed. 5) Evidence for slumping: The dark-gray, organic-rich siltstone (lower right of pan) has an irregular, antiformal geometry and drapes an erosion surface that is located within the underlying light-colored laminated siltstones. This erosion surface has at least 10 m of erosional relief, and is interpreted (based on its irregular geometry) as an evacuated slump scar. Topographic lows on this basal, slump-related erosion surface at least partially controlled

the location of overlying sand-filled channels. Additionally, contorted bedding near the base of some channel fills suggests local slumping was associated with channel initiation. 6) Overall vertical stacking patterns: Sandstone Channel Fills # 1-5 are vertically-stacked, reflecting either up-dip point-source control, or influence of pre-existing topographic features such as the slump-related erosion surface at the base of the section. Lower channel fills are only partially preserved, due to intercutting of master erosion surfaces, but become more completely preserved upwards. These relationships suggest increasingly aggradational conditions of deposition at this locality during Upper Brushy Canyon time.

Figure 2.2a Channel Fill Types High nerg Fill

1 PALEOCURRENT

Erosional Fill Example: Fusulinid-rich sanstones, upper half Sandstone Channel 3

INDICATORS FOR CHANNEL 2 CHANNEL TREND

Moderately erosional, onlapping fill with complex channel margins Example: Sandstone Channel 4(SE margin) PALEOFLOW ALONG CHANNEL MARGIN

Onlapping fill with facies changes toward margins and development of channel margin drapes Examples: Sandstone Channels 2, 3 and 4

1 Low Energy Fill

B4 N.31

I

MEAN = 134

PALEOFLOW OUTSIDE CHANNEL

"Passive"(nonerosional) onlapping fill Example: Sandstone Channel 1 (right side of siltstone "antiform")

Figure 2.2e. Detailed view of onlapping sandstone aeometries and development of thinbedded d r a b along channel-margin of Sandstone Channel 2.

Figure 2.2b Complex Channel Margin, SE margin of Sandstone Channel 4. The channel margin is characterized by stacked erosion surfaces and erosional remnants of small-scale sandstone channel fills. These geometries indicate a complex history of repeated erosion and at least minor backfilling early in the channel's history, before later, more aggradational, back-filling by laterally-extensive, onlapping sandstones.

Figure 2.2~. Non-amalgamated, onlapping sandstone fill at axis of Sandstone Channel 2. This style of channel fill is common to all the Guadalupe Canyon slope channels. Sandstone beds are medium- to thick-bedded and internally massive. Sandstones typically thin towards channel margins into very thin sandstone beds, which are interbedded with thin siltstones and form composite "drapes" along channel margins (see Photo 2).

Figure 2.2d. Margin of Sandstone Channel 2 showing progressive thinning of non-amalgamated channel-filling sandstones towards channel margin. The master channel erosion surface is separated from the base of the onlapping sandstones by a thin recessive zone of inclined, thin-bedded sandstones and siltstones which mantle the channel margin. Dip angles within the "drapes" typically flatten upwards. Arrows show lateral thinning of channel-filling sandstones into thin sandstone beds or laminae which form part of this composite drape.

Arrows mark lateral thinning of sandstone beds into zone of inclined, thin-bedded sandstones and siltstones forming channel-margin "drape". Master erosion surface is present below base of photo. Onlapping sandstone geometries at channel margins result in local thickeningupward bed thickness trends.

Slope

Depositional Interpretation Figure 2.3 Summary of Middle Slope Channel Complexes

Channel Characteristics Channel Geometries: Large (up to 45 m deep), low aspect ratio sand-filled channels confined by master erosion surfaces incised into slope siltstones. Bypass Indicators: Siltstone-draped erosion surfaces are common and coarsegrained lags are locally present. Thin intervals containing internal erosion surfaces, very thin lenticular sandstones and "starved"ripples occur near the base of some channel complexes and may represent the record of protracted bypass through the channel. Channel F i l l s : In this setting, large-scale erosion surfaces are commonly overlain by thin-bedded sandstones and siltstones. These

thin-bedded fme-grained intervals may fill entire channels, or form the initial fill in otherwise sandstone-dominated channel fills. Sandstone channel fills are variable in style, but are dominantly composed of non-amalgamated, medium- to thick- bedded massive sandstones that are laterally extensive from channel axis to channel margin, and which thin abruptly at channel margins into composite "drapes" composed of interbedded, thin sandstones and siltstones.

Stacking Patterns: Vertical to slightly offset channel stacking patterns are common and indicate focusing of flow by nearby upperslope canyons. Evidence for slump-related features indicate that pre-existing topography may be an additional con trol on channel locations and stacking.

The section at Guadalupe Canyon is dominated by a set of vertically-stacked channel complexes. These complexes are interpreted to have been situated on the mid-slope and to represent "feeder"channe1s into the basin. The middle slope setting for these channels is based on: 1) their geographic and stratigraphic position, 2) their relatively large size, 3) the presence of thick intervals of slope-building laminated siltstones, 4) common slumps within the siltstones suggesting relatively high gradients, and 5) a vertcal stacking of channels suggesting deposition not too far downdip of a fixed point-source.

most of the Guadalupe Canyon channels. The non-erosional character of these sandstone beds, together with a characteristic facies change at their margins from massive beds to thin-bedded, low-density turbidites, suggests emplacement by relatively slow-moving flows in a strongly depositional mode. These flows were quite different from those that cut the erosional channel containers. The lower energy style of fill is potentially associated with late-stage backfilling of the slope channels during times of relative sealevel rise when the sediment flux to the slope was greatly reduced.

The Guadalupe Canyon slope channels are interpreted to have had long periods of sediment bypass prior to their filling. During these intervals, each channel served as a transport conduit into the basin. Key features suggesting significant sediment bypass include: 1) the large size of the master erosion surfaces, 2) evidence for repeated cutting and filling in the basal, axial portions of some channel fills, and 3) local coarse-grained lags.

In general, Brushy Canyon slope channels exhibit greater variability in fill styles than do Brushy Canyon channels on the basin floor. This variab'ility is attributed to the tendency for slope channels to be filled by flows over a greater interval of time and later in the relative sea level cycle than associated basin floor channels. Differences in fill styles between slope channel complexes fed by different point sources reflect variations in the "caliber" or importance of the point source as a sediment contributor, and variations in the character of flows delivered to the slope at the time of back-filling.

A significant hiatus between channel cutting and channel filling is also suggested by the character of the laterallyextensive, non-amalgamated, massive sandstones that fill

Figure 3.la

PALEOCURRENT INDICATORS

PALEOCURRENT INDICATORS

PALEOFLOW ACROSS CHANNEL MARGIN

PALEOFLOW ACROSS CHANNEL MARGIN

MEAN = 28

RIPPLE MARKS IN THIN-BEDDED NRBlDlTES ALONG NORTHWESTERN MARGINS OF CHANNELS INDICATE FLOW AWAY FROM AND TOWARD CHANNEL AXlS

CHANNEL TREND CHANNEL MARGIN STRIKE MEASUREMENTS

1

RIPPLE MARKS INTHIN-BEDDED

TURBlOlTES ALONG NORTHWESTERN MARGINS OF CHANNELS INDICATE FLOW AWAY FROM AND TOWARD CHANNEL AXIS

/

CHANNEL TREND

MEAN = 320

Figure 3.1b

% N=ll

PALEOCURRENT INDICATORS CHANNEL TREND

I

I

CHANNEL MARGIN STRIKE MEASUREMENTS

MEAN =SO

N.12

PALEOFLOW ACROSS CHANNEL MARGIN

CHANNEL MARGIN STRIKE MEASUREMENTS

RIPPLE MARKS IN DRAPES ALONG SOUTHERN MARGIN OF CHANNEL INDICATES FLOW SLIGHTLY OBLIQUE TO CHANNEL TREND

I

1

Figure 3 . 1 ~

Figure 3.1d

Figure 3.1. Overview of Delaware Mountain and Buena Vista outcrop localities(Upper Brushy Canyon Frn.). 3.la. T h i s photo s h o w s a l a t e r a l l y extensive, s a n d - p r o n e channel c o m p l e x in the U p p e r B r u s h y Canyon m e m b e r that i s i n t e r p r e t e d as a major feeder c h a n n e l complex d e p o s i t e d in a l o w e r s l o p e (toe-of-slope) setting. T h e channel cam-

plex i s 80 m thick. The a x i s o f t h e c h a n n e l complex i s c h a r a c t e r i z e d by thick, a m a l g a m a t e d sandstones. T o w a r d s t h e m a r g i n s of the c o m p l e x , these amalgamated sandstones b e c o m e l e s s amalgamated, a n d separate into l a t e r a l l y per-

sistent s a n d s t o n e l e d g e s that a r e separated by recessivew e a t h e r i n g s i l t s t o n e intervals. T h e outcrop belt i s a p p r o x i r n a t e l y 1 km long and o r i e n t e d a t a highly o b l i q u e a n g l e to the SE-E trend of c h a n n e l s within t h e c o m p l e x . 3.1

3.lb,c,d. P a l e o c u r r e n t m e a s u r e m e n t s for l o c a t i o n s r e f e r e n c e d in F i g u r e 3.la.

EPR Co. Buena Vista #I

EPR Co. Buena Vista #2

Figure 3.2 Photograph c,f Buena Vista locality within the Upper Brushy Canyon Member an1d the locations of the Buena Vista # and l #2 researc:h boreholes. This outcrop contains two 5th order stratigraphic units interpreted as lower slope channel complexes separated by a laterally extensive siltstone bed ("marker bed"; see following pages). The base of the Upper Member is interpreted as a sequence boundary (4th order) and abruptly overlies a prominent, laterally extensive siltstone interval known as the 40 foot siltstone (Zelt and Rossen, 1995). The 40' siltstone is included within the Middle Brushy

Canyon Member and is interpreted to represent a 4th order lowstand wedge (LSW). From this view the highly channelized internal character of the complexes is evident. Major erosion surfaces within the complex are highlighted in red, secondary erosion surfaces are highlighted by thick black lines, and interpreted abandonment surfaces (overlain by laminated siltstones) are marked in blue. Major erosion surfaces within the channel

complex typically have 10-15 m (30-50 ft) of erosional relief. Erosion surfaces associated with the southern margin of the upper complex (upper right-hand side of photo) exhibit 50-60 feet of incision along a complex, inclined zone. Major erosion surfaces within the channel complex are typically overlain by lenticular, coarse-grained sandstones (resistive, rusty brown beds on pan) that are interpreted as lags deposited hactively from high-velocity, bypassing flows. Secondary erosion surfaces within the complex have ero-

sional relief of 5-10 m and may stack vertically within the confines of major erosion surfaces. These secondary erosion surfaces are filled with thick-bedded, amalgamated sandstones and typically lack lags. The complexly intercutting character of major and minor erosion surfaces suggests a protracted evolution including repeated episodes of downcutting, sediment bypass, channel backfill and abandonment.

PALEOCURRENT INDICATORS CHANNEL TREND MEAN = 60

CHANNEL MARGIN STRIKE MEASUREMENTS

1

1

PALEOFLOW WITHIN CHANNEL PARTING LINEATIONS IN LAMINATED TURBIDITES NEAR AXIS OF CHANNEL INDICATE FLOW PAPALLEL TO CHANNEL

PALEOFLOW OUTSIDE CHANNEL RIPPLE MARKS IN CHANNEL-MARGINAREA A N 0 IN OVERBANK ADJACENT TO CHANNEL

N=41

INDICATES FLOW AWAY FROM CHANNEL

mun= 149 Figure 3.3b Figure 3.3a

oase or are tractively-

I

~ermearneter~ h a n n e c~ h & edeposits of low concentration turbidity currents have been interpreted both as: 1) bypass facies deposited from the dilute :lasts. Numerous Internal scour tails o f bypassing flows, and 2) low?ssuggest that these sands repenergy back-filling facies that are preferthe thin tractive deposits of multientially p r e s e ~ e dalong the channel gh-energy, bypassing flows. margin. Figure 3.3. Lithofacies and stratal geometries preserved along Permeameter Channel margin, Buena Vista, Upper Brushy Canyon Formation.

3.3a. This figure shows the margin of the "Permeameter" channel which occurs along the SE flank of the Buena Vista channel complex (see Figure 3.2). 3.3b. Paleocurrent measurements taken along the southern margin of Permeameter Channel. The Permeameter Channel illustrates a vertical progression of fill types, and facies variations from channel axis to margin, that are characteristic of many other channels within the Buena Vista channel complex. The "Permeameter" fill succession consists of:

1) Erosion of basal erosion surface.

2) Lenticular, coarse-grained, traction-laminated sandstones along margin of channel(Fig. 3.3~). 3) Thin-bedded, low concentration turbidites that drape the channel margin. These thin-bedded turbidites may be complexly interleaved with small-scale erosion surfaces and lenticular coarse-grained sandstones, or may occur as evenly bedded units that thicken toward channel axes(Fig. 3.3d,e).

4) Thin-bedded channel margin turbidites are typically removed toward the channel axis by younger erosional surfaces that are typically infilled with thick-bedded, amalgamated sandstones.

5) Repetition of 3) and 4) may produce a complex, interfingering pattern between thick-bedded, amalgamated channel-filling sandstones in the channel axis, and thinbedded turbidites at the channel margin.

internal scour surfaces and lenticular, coarse-grained lags.

6) Abandonment, or erosional incision and repetition of the cycle. This fill succession is interpreted to represent an overall cycle of: 1) erosion, 2) predominant sediment bypass, and 3) depositional back-filling of erosional relief. The more complex stratal relationships within the Permeameter Channel indicate that the channel fill stages represent numerous cutting, bypassing and back-filling events.

South

Laminated Siltstone

IThii-bedded Sandstones Thin-bedded Sandstones

- - -

R DEN RES

-

T g ofoutcrop

PI' w-

l ~ a r k e Bed r (Zelt & R-n,

-I

1995)

-approx. 100 feet I Figure 3.4. This diagram shows the uppermost Brushy Canyon Formation at the Buena Vista locality. Also shown are the locations of research boreholes drilled in 1998 (the actual location of Buena Vista #2 is slightly north of this area). See figures on previous and following pages for additional information. Only the logs for the interval above the marker bed are shown. Figure 3.4b

This figure emphasizes the relationships between the axis and southern margin of a large, erosionally-confined channel complex that occurs above the "marker bed" and that is interpreted to have formed in a toe-of slope depositional environment. The "marker bed" is an organic-rich siltstone (0.6 m thick) that contains ashbeds and that can easily be correlated on photo pans and measured sections for over 15 km to the northern limit of the Delaware Mountains. The "marker bed" is interpreted as a condensed interval that

marked widespread abandonment of submarine fan systems during Upper Brushy Canyon time. The marker bed is truncated immediately south of the Buena Vista #1 well by an erosional surface at the base of a younger channel system (interval A on sketch). Channel system A is overlain in the south by a succession of medium-bedded sandstones and interbedded siltstones (interval B) that represents another channel system located to the south. Intervals A and B are progressively truncated northward of Buena Vista

#1, and are ultimately completely removed by erosion at the base of the channel complex in interval C. The base and southern margin of the complex are bounded by composite erosion surfaces composed of numerous discordant surfaces. The minimum depth of erosional relief is estimated at 120 feet. The southern margin of the complex is a steep, recessive-weathering zone composed of onlapping thin-bedded turbidites, draping siltstones, and thin lag deposits. Numerous channel margin remnants exist within

this zone, indicating multiple cycles of erosion and deposition and a highly protracted initial phase of evolution. In the axis of the channel complex, the channel base is overlain by a thick lag complex. Overlying the lag complex is a thick package of thick-bedded, massive and amalgamated sandstones that represent the axial fill of the complex. These sandstones exhibit crude horizontal stratification, onlap abruptly along the southern channel margin and represent a rapid, highly aggradational ("plugging") style of fill.

EPR Co. Buena Vista #I Up er Brushy Member Brus y Canyon Formation Six Bar Ranch, West Texas

R

RES (SO)

I.5O Ta, Td

Ta, Td

al

Ta

m

I

I' Td,Te

O.B.

Figure 3.5. Core Summary Plot

The EPR Co. Buena Vista #1 well penetrates the upper member and the top of the middle member of the Brushy Canyon Formation. The Buena Vista outcrop is oriented slightly oblique to the paleo-flow direction (see Fig. 3.4), therefore provides a depositional strike perspective. At Buena Vista, the upper member is interpreted as lower slope deposits and characterized by deeply incised channels. This core summary-plot illustrates the relationship between well-log patterns, core lithofacies associations and environments of deposition. Dominating the cored interval is approximately 240 feet of stacked channel-axis and channelmargin deposits for the upper confined channel complex (UBC-2) and predominantly channel-axis deposits for the lower confined channel complex (UBC-1). Channel-axis deposits are dominated by highly amalgamated, normally graded, massive to cross-stratified sandstones deposited primarily by high-concentration turbidity currents. In these channels the highly erosional basal surfaces are commonly overlain by lenticular units of rip-up clast conglomerates or fusulinid-rich sandstones. Channel-margin deposits are dominated by onlapping, erosionally bounded, thin-bedded, lowconcentration turbidites and inter-bedded thin, lenticular coarse-grained sandstones.

TR, Ta

Ta Ta, TR Ta

I

ash bed.---

I

Middle Brushy Canyon FM Upper Brushy Canyon UBC-1 Canyon 0Upper Brushy UBC-2

80' siltstone

,' p

t T

M.D. Sullivan 6 S.J. Fri

TR =Traction deposit Ta = massive sst. Tb = planar-stratifiedsst. Tc = current ripple dominated sst. Td = planar-stratifiedshaly sst. Te = planar-stratifiedto massive mdst.

C.A. = Channel Axis deposit C. M. = Channel Margin O.B. = Overbank deposit C.C.C.= Confined Channel Com~lex

a = bioturbation M = massive bedding = ash bed 41 = current ripples a = contorted beds a:. = fusulinids .2-= trough cross-beds --= water escape structures

EPR Co. Buena Vista #2

r:

Up er Brushy Member Brus y Canyon Formation Six Bar Ranch, West Texas

Figure 3.6. Core Summary Plot

'd, Te

rc, TC -

Te

The EPR Co. Buena Vkta #2 well penetrates the upper member of the Bmshy Canyon Formation. The Buena Vista outcrop is oriented slightly oblique to the paleo-flow direction (see Fig. 3.4), therefore provides a depositional strike perspective. At Buena Vkta the upper member is interpreted as lower slope deposits and characterized by deeply incised channels. This core summary-plot illustrates the relationship between well-log patterns, core lithofacies associations and environments of deposition. Dominating the cored interval is approximately 250 feet of stacked channel-axis deposits for the upper confined channel complex (UBC-2) and a mixture of channel-margin and channel-axis deposits for the lower confined channel complex (UBC-I). Channel-axis deposits are dominated by highly amalgamated, normally graded, massive to cross-stratified sandstones deposited primarily by high-concentration turbidites. In these channels the highly erosional basal surfaces are commonly overlain by lenticular units of rip-up clast conglomerates or fusulinid-rich sandstones. Channel-margin deposits are dominated by onlapping, erosionally hounded, thin-bedded, low-concentration turbidites and inter-bedded thin, lenticular coarse-grained sandstones.

Middle Brushy ~ a n v o nFM Upper Brushy Canyon UBC-l

[7 Upper;!E;rr

C.A. = Channel Axis deposil C. M. = Channel Marain 0.6. = Overbank deposit C.C.C.= Confined Channel Complex

-

Canyon

a = bioturbation TR =Traction deposit Ta = massive sst. Tb = ~lanar-stratifiedsst. Tc = current ripple dominated sst. Td = planar-stratified shaly sst. Te = planar-stratified to massive mudstone.

M massive bedding .... = ash bed = current ripples =

. .

.

-I

" == fusulinids beds

a= trough

-

cross-beds

-= water escape

structures

'

& o,'& '

Brus

EPRCo. Buena ." Vista #2

EPR Co. Buena Vista #I Approximate Area of

Siltstones

Pebbly Sandstones (Lags)

Thick-bedded Sandstones (Channel Axis)

Thin-bedded Sandstones (Channel Margin)

Figure 3.7. This diagram illustrates the calibration of the Buena Vista well logs to the outcrop and the bedding correlations between the two borehole locations. Refer to previous pages for locations of the Buena Vista #I and #2 sites and additional information. For purposes of illustration, facies associations have been simplified as follows; siltstone (abandonment intervals), pebbly sandstones (channel lags), thick-bedded sandstones (channel axis facies), and thin-bedded sandstones (channel margin facies). The Upper Brushy Canyon Member at Buena Vista can be subdivided into two 5th order units (UBC-1, UBC-2) and several 6th order units. The 5th order units are interpreted as lower slope, or toe-of-slope

channel complexes while the 6th order units represent stories within the fill of the complexes. UBC-1 is characterized by numerous, relatively shallow, nested channels. These channels have margins that generally stack in the vicinity of the Buena Vista #2 location, and axes that preferentially stack in the vicinity of the Buena Vista #1 location. By contrast, the UBC-2 complex

represents a highly amalgamated, deeply incised system with its southernly margin located at the site of Buena Vista #1, and its axis at BuenaVista #2. Although the axial fill of the UBC-2 complex consists of amalgamated channel sandstones that simply onlap the base UBC-2.3 surface to the south, the margin of the complex is quite complicated and records a protracted history of multiple episodes of erosion, bypass and deposition. A more detailed study of

the southern channel complex margin is indicated on the upper right-hand side of the diagram and shown on the following page. This diagram illustrates the difficulty of accurately correlating well logs for closely spaced wells within this depositional setting. This work was accomplished as part of the Exxon Exploration Co. Deep-Water Internship Program in collaboration with the Exxon Production Research Co. Deep-Water Reservoirs Group.

30ft (vert)

I

-

30ft (horiz)

I Sandstone:Truncated MarginWedges

Massive to Bedded Sandstone

L

rn

'Pinstripe' lithofacies: Dipping Siltstone and Ripple-Laminated Sandstone

.

410 ft

Coarse Lag: Sandstone, Clasts, Fusinlllds

Thin-bedded SandstoneISiltstone Slltstone: Abandonmenfflnterchannel

-

Eroslonal Surface

Jennene, Beaubouef (EPR). Jensen, Brami, Wilson, Ardili, Tate, Keidell. Fergusan(EEC)

Figure 3.8. This diagram illustrates the complex stratigraphic relationships along the southern margin of the upper channel complex at the Buena Vista outcrop locality. See Fig. 3.7 for location of sections. The Buena Vista #1 well log and core project into the line of section in the vicinity of measured section IN. The lithofacies designations used in this diagram are slightly different than those of previous pages, and consist of: massive to bedded sandstones (channel axis facies), "pinstripe" facies (inclined thin-bedded siltstones and sandstones within the channel margin), sandstone (erosionally truncated wedges of medium-bedded sandstone within the margin), coarse lag (pebbly sandstones within the margin), thin-bedded sandstone and siltstone, siltstone (abandonment facies). Prominent erosional surfaces are shown in green. Datum 1, the "marker bed", is truncated to the

south. Datum 2 is an abandonment surface that is truncated to the north. The channel margin zone is a steeply dipping lens that contains a variety of lithofacies and numerous internal surfaces. Note that the prominent erosional surfaces that bound the lens dip at a high angle relative to internal bedding. These surfaces are correlated to the base UBC-2.3 surface in Buena Vista #2 (previous page) and intersect in the northem part of the section. Hence, the strata contained within the

margin do not extend into the axis of the complex. The channel margin zone includes several horizons of channel lags and truncated channel margin wedges that thin, change facies and onlap smaller scale channel margins within the lens. These relationships indicate a protracted evolution that included repeated cycles of erosion, bypass, and channel filling followed by resumed erosion. Significant thickness of channel fill must have existed prior to each erosional episode, and erosional down-cutting occurred to similar stratigraphic levels in each erosional episode. By contrast,

the final filling of the complex was accomplished by deposition of horizontally-bedded, massive sandstones that simply onlap the upper surface of the channel margin lens without appreciable facies changes toward the margin. In general these relationships indicate; a) an early phase of alternating bypass and channel filling and, b) a late phase of channel back-filling or "plugging". This work was accomplished as part of the Exxon Exploration Co. Deep-Water Internship Program in collaboration with the Exxon Production Research Co. Deep-Water Reservoirs Group.

Bash Floor

Figure 3.9. Summary of Toe-of-Slope Channel Complexes

Channel Characteristics

Channel Fills:

Channel Geometry:

- Thick-bedded, amal

relief (5-15 m) erosional channels with simple to complex margins.

ting) and characterized by laterally-offset channel stacking patterns.

:hannel fills are common, particularly within fills of secondary(minor) channels.

Depositional Interpretation

Margins of major erosion surfaces are commonly overlain or "draped" by inclined wedges of thin-bedded sandstones and siltstones containing common internal erosion surfaces.

The absence of thick slope siltstone intervals and the transition from vertical channel stacking patterns (observed in slope areas) to laterally-offset channel stacking patterns suggest deposition in a less confined, lower slope setting.

- Moderate

Bypass Indicators: -

-

Lenticular, coarse-grained lags are common along the base of major erosion surfaces. Siltstone-draped scours are present, but not common.

-

Associated Facies and Channel Stacking Patterns: Channels are typically incised into other channel-fill sandstones (not into slope siltstones as in the slope channel set-

The abundance of coarse-grained lags at this locality is attributed to loss of gradient at the toe-of-slope. Lags are less abundant in areas located depositionally updip and downdip from this locality.

Low-density turbidites preserved in thin-bedded channel margin drapes above lagged erosion surfaces are welldeveloped in this depositional setting. This facies may represent either: 1) a bypass facies deposited from the dilute tails of bypassing high-energy turbidity currents, or 2) lowenergy back-filling facies. Complexly intercutting erosion surfaces, and cyclic fill styles suggest low rates of aggradation, and repeated episodes of erosion, bypass into the basin, and back filling by high energy flows.

Figure 4.1. A paleogeographic reconstruction for the Lower Brushy Canyon (map to right) shows that Lower Brushy Canyon sandstones were deposited on the basin floor, in E-SE trending submarine fan complexes.

The submarine fan complexes are interpreted to consist of down-fan bifurcating channel networks which feed unconfined sheet complexes in the outer reaches of the system. Lower Brushy slope deposits are poorly preserved in outcrop, therefore the depiction of the slope is schematic. The Lower Brushy Canyon fans are interpreted to pinchout updip onto the toe-of-slope in the area located just south of the Guadalupe Mountains. The Lower Brushy slope may have largely consisted of relict carbonate slope deposits.

t

APPROXIMATE LOCATION

Within the basin-floor fans, four main depositional environments are recognized:

1) Proximal Channelized Fan: Relatively large channels are incised into pre-existing channel and inter-channel strata. These channels exhibit simple erosional bases. Channel fills, consisting of amalgamated, thick-bedded sandstones, suggest rapid, back-filling by high-energy flows. Lags and siltstone-draped erosion surfaces are rare.

2) Medial Channelized Fan: Channels of moderate-scale are common and occur in association with tabular (broadly channelized to sheet-like) sandstones and interbedded siltstones. Compared to proximal fan channels, medial fan channels are characterized by simple channel margins and amalgamated channel fills, but have greater widthldepth ratios and are arranged in laterally offset stacking patterns.

3) Channel to Sheet lkansitions: Broad shallow channels show a distinct, genetic association with laterally adjacent tabular sandstones. Channel margins are characterized by multiple low-relief erosional surfaces that pass laterally from the amalgamated channel axes into relatively conformable medium- to thick-bedded interchamel sandstones. Although the tabular, sandstones appear sheet-like, individual beds are typically lenticular, and exhibit compensatory vertical stacking patterns.

4) Sheet Complexes: This environment is characterized by laterally extensive, amalgamated to non-amalgamated, medium- to thick-bedded sandstones that form compensationally-stacked bedsets. Channels are generally absent. Erosional scours, if present, are broad and shallow, and typically have less than 1 m relief.

1 Figure 4.2a

Figure 4.2. Proximal Basin Floor: Popo Channels, Middle Brushy Canyon Formation.

4.2a. Oblique depositional strike perspective of proximal fan channels of the middle member of the Brushy Canyon Formation

Dominating this exposure are laterally offset, erosionally based, narrow (low aspect ratio) channels and interchannel sheets. In contrast to the deeply incised slope channels of the upper member, these channels exhibit simple erosional bases, are much less incised and have higher width to thickness (aspect) ratios. Some erosional surfaces associated with the channel bases are overlain by coarse lags.

Channels tend to be filled from axes to margins by fine grained amalgamated, thick-bedded cross-stratified sandstones exhibiting aggradational bed forms. These features suggest deposition from long-lived currents and relatively high sedimentation rates. Significant facies changes from axis to margin are not observed and the sandstones abruptly terminate by onlap along channel margins. Genetic associations between channel and interchannel strata are not obvious. The interchannel strata are comprised of nonamalgamated thin- to thick-bedded laminated to massive sandstones and interbedded siltstones. These features are

cited as evidence for a channel evolution that includes: a) an early phase of bypass and deposition from only the bedload portions of through going flows followed by b) a very rapid, aggradational ("plugging") style of fill, followed by c) a lateral shift in the axes of deposition.

4.2b. Example of cross-stratified, fine-grained sandstone characteristic of channel axis deposition. This stratification was produced by a train of bedforms (e.g., dunes) migrating down the channel during sustained turbidity-current flow. Aggradation of the channel bottom due to the rain of

suspended sediment out of such a turbidity current was typically high enough to bury and preserve the stoss sides to many of the bedforms. These supercritically climbing bedforms indicate that the filling of the channels was primarily associated with spatial, not temporal, deceleration of the currents. Estimates for the durations of these currents, as well as for their velocities at the sites of deposition, can be constrained through analysis of bedform geomeby (height, length, and plan-form), bedform climb angle, and grain size.

Large erc

~ a channel l on bas n s l fan

q r ~ ~ bhRcw

I

CHANNEL TRENDS UPPERCHANNEL

I

CHANNEL MARGIN STRIKE MEASUREMENTS

LOWER CHANNEL

Figure 4 . 3 ~ .Proximal-margin

Figure 4.3b. Channel-axis Figure 4.3. Proximal Basin Floor: Brushy Mesa, Lower Brushy Canyon Formation. 4.3a. Oblique depositional strike perspective of proximal fan channels of the lower member. Dominating this exposure are laterally offset, erosional based, narrow (low aspect ratio) channels and interchannel sheets. Channels tend to be filled from axes to margins by amalgamated, thick-bedded sandstones suggesting rapid filling of chan-

nels by high-concentration turbidity flows. The interchannel strata are comprised of non-amalgamated thin- to thickbedded massive sandstones and interbedded siltstones. 4.3b. Channel-axis deposits are dominated by thick-bedded, high-concentration turbidites characterized by fine- to medium-grained, massive sandstones. The channel fill is

characterized by repetitive sandstones that are fusilinid-rich at their base and grade upward into massive sandstone. 4.3~.Channel-margins are also dominated by highly amalgamated massive sandstones. Note the simple onlap of thick-bedded massive sandstones onto the margin of the channel. Onlapping siltstones are locally preserved along

the margin and may be related a) to an early phase of transmission prior to channel plugging orb) temporary abandonment of the channel following initial erosion. 4.3d. Paleocurrent measurements for the proximal fan channels at Brushy Mesa.

al Bas

\

Shelf

Figure 4.4. Summary of Proximal Basin Floor Channel Complexes Channel Characteristics Channel Geometry: Laterally offset, erosional based (5-20 m thick), narrow (75-230 m), low aspect ratio channels that tend to be both vertical and laterally amalgamated to produce very continuous composite sandbodies separated by interchannel sheet sandstones. Channel Fill: Channels tend to be filled from axes to margins by amalgamated, thick-bedded massive sandstones suggesting rapid

filling of channels by high-concentration turbidite flows. Often, cross-stratification is observed, which suggests sustained flow and high depositional rates within channels. In some cases, channel fill shows a decrease in amalgamation toward the margins, but significant facies changes toward margins are rare.

Interchannel Association: Interchannel strata associated with these channels consist of non-amalgamated thin- to thick-bedded massive to current ripple laminated sandstones and interbedded siltstones. Genetic associations between interchannel and channel fill strata are not obvious.

Bypass Indicators: Although coarse lags are observed in some outcrops, their proportions are low relative to middle and lower slope channels. In general, the evidence for bypass is represented only by an erosional surface.

Depositional Interpretation These channel complexes are interpreted to have formed in a proximal basin floor setting. This interpretation is based on: a) the absence of associated thick slope siltstone intervals, b) laterally-offset, weakly incised channels rather than ver-

tically stacked, deeply incised channels like those observed in the slope, c) simple, rather than complex channel margins, d) highly amalgamated sandstone channel fills, and e) lower proportions of bypass indicators compared to lower slope channels.

Colken Canyon, Lower Brushy Canyon Formetion . .

--

(

TREND OF CHANNEL

Figure 4.5a

.

Figure 4.5b. Axis to margin transition. Figure 4 . 5 ~ . Sheet complexes aajacenr ro cnannel complex.

-channelized Figure 4.5. Medial Fan: Colleen Canyon, Lower Brushy Canyon Formation. These outcrops are interpreted to represent the transition between channelized and non areas of the basin floor and are described as distributary channel complexes. 45a. Depositional strike perspective of a broad (350 m), relatively shallow (20 m) channel with extremely continuous sheet-like margins that can be traced laterally for several thousand feet. Surfaces from within the channel-axis can be traced into the adjacent beds indicating a genetic relationship between the channel and the sheet-like margins. Channel-axes are comprised of thick-bedded, commonly cross-stratified amalgamated sandstones that are replaced toward the channel margins by progressively thin-

ner-bedded, less amalgamated sandstones. The channel margin is formed by several, vertically stacked erosional surfaces that exhibit up to 9 m of relief. The degree of erosion decreases substantially into the adjacent sheet-like sandstone "packages". Sandstones within these continuous "packages" are generally massive internally and interpreted to have been deposited rapidly from suspension. Loaded bedding contacts, flame structures and evidence for dewatering are abundant and indicate high rates of deposition.

Although the sandstone "packages" are highly continuous, lenticular and compensational bedding styles and small scale scour surfaces are common within them. Also shown are paleocurrent indicators for the channel and adjacent strata.

4.5b. Enlarged view of main channel showing transition from channel axis, amalgamated sandstones to channel margin, semi-amalgamated sheets. 4 3 . View looking east

Figure 4.5e. Cross-stratified sandstones in channel axis.

showing the thick-bedded character and overall high continuity of channel margin sandstones lateral to the axis of the channel complex. 45d. Thick succession of amalgamated, trough cross-bedded sandstones in the axis of the channel complex. 4.5e. Example of trough cross-bedded sandstones characteristic of axial channel fill. These bedforms suggest long-lived currents and high sedimentation rates.

Figure 4.6. Colleen Canyon, Lower Brushy Canyon Formation: Outcrop to Well-Log Calibration. These photos show the Colleen Canyon area as viewed from SSE. 4.6a. This outcrop is contained in the down-thrown fault block east of the ranch road and is a southern view of the same channel complex illustrated on the previous page. Also shown is the location of the EPR Co. Colleen Canyon #1 research borehole drilled in 1998. In this perspective, almost the entire thickness of the lower member (4th order sequence) can be seen. The basal Brushy Canyon Formation rests sharply above an approximately 50m thick

interval of Pipeline Shale. The Brushy CanyonPipeline Shale contact is the base of the Brushy Canyon lowstand sequence set (3rd order SB). Based on the presence of a highly condensed interval at the base of the "middle reces. sive" observed in core (see following page), the lower member can be subdivided into two sandstone-rich 5th order units. Lateral equivalents to the channel complex seen on the previous page occur in the upper half of the

lower unit. These packages can be further subdivided into several thinner, but highly continuous sandstone "packets" (6th order?).

4.6b. Enlarged view of the site of the Colleen Canyon #1 borehole site with well logs tied to the outcrop. Note that the continuous channel margin deposits exhibit internal regions of greater and lesser degrees of amalgamation,

which allows them to he divided into sheet-axis and sheetmargin associations, respectively. The sheet-axis deposits are dominated by amalgamated, normally graded to massive, fine-grained sandstones with or without internal erosion surfaces. Sheet-margin deposits are dominated by non-amalgamated, fine-grained sandstones.

EPR Co. Colleen Canyon #1 Lower Brushy Member Brushy Canyon Formation Six Bar Ranch. West Texas

:igure4.7. Core Summary Plot

Ta

Ta Tc Td I, c-d

Ta -

Td Ta Td Ta

m Ta

h e EPR Co. Colleen Canyon #1 well penetrates the lower iember of the Brushy Canyon Formation and the basal :rushy Canyon Formation sequence boundary. The Colleen :anyon outcrop is oriented slightly oblique to the paleo-flow irection (see Fig. 4.5a), therefore provides a depositional trike perspective. In the Colleen Canyon area, the lower lember is interpreted as medial fan deposits representing the ansition between channelized and non-channelized regions f the basin floor. his core summary-plot illustrates the relationship between $ell-logpatterns, core lithofacies associations and environlents of deposition. Dominating the cored interval is pproximately 230 feet of stacked sheet-axis and hannellsheet-margin deposits. The well is located in a marinal position relative to the main channel-axis and comrised of extremely continuous "packets" of semi- to nonmalgamated, massive to cross-stratified sandstones. Sheetxis deposits are dominated by amalgamated sandstones and ~eet-marginsare dominated by non-amalgamated sand:ones. In both sheet axis and sheet margin deposits, sedilentary structures suggest rapid deposition from suspension y high concentration turbidity currents.

Ta

b,Tc Ta Ta

Lower Brushy Canyon

Ih Ta

C.A. = Channel Axis deposil C. M. = Channel Margin O.B. = Overbank d e ~ o s i t C.C.C.= Confined Channel Complex

-

Td M.D.

TR = Traction deposit Ta = massive sst. Tb = planar-stratified sst. Tc = current ripple dominated sst. Td = planar-stratified shaly sst. Te = planar-stratified to massive mudstone.

a = bioturbation M massive bedding .... = ash bed -' current ripples = =

a = contorted beds = fusulinids &=trough cross-beds --=water escape structures

Shelf Slope

V

Figure 4.8. Summary of Medial Basin Floor Channel Complexes

Channel Characteristics C h a ~ e Geometry: l

Depositional Interpretation Associated Facies:

Channel Fill:

These channel complexes are interpreted to have formed in a media] basin floor setting characterized by a distributive depositional environment. The prominent channel complex in colleen canyon is interpreted as a major trunk channel smaller channels and sheet axes are interpreted as dis. tributary channels within a distributary channel complex. This interpretation is based on:

sandstones

a) low relief and broad width of channel complexes,

Broad, shallow channel complex characterized by vertically-stacked, low-relief (< 10 m) erosion surfaces that pass laterally into relatively conformable, interchannel areas that exhibit only minor channelization.

Channel complex is incised into laterally extensive, tabular sandstone "packets" containing lenticular, locally erosive, loaded or dewatered generally massive sandstones.

- Axis of complex: amalgamated, trough cross-laminated - Flank of complex: non-amalgamated, medium to thickbedded, tabular sandstones that are often internally structureless

b) the continuity of beds from channel axis to channel flank.

c) evidence for rapid deposition from suspension in the absence of confinement in the channel flank areas, and d) evidence for minor focusing of flows within a relatively unconfined setting outside the main channel axis.

Dominating the Lower Brushy Canyon Formation in this portion of the outcrop belt are sharp based, generally non-amalgamated turbidite sheet complexes.

Figure 3.1. uurer ran: Cordoniz Canyon, Lower Brushy Car.,

. -..nation.

5.la. This photograph illustrates the "packaging", stacking patterns, and bedding styles of sandstone sheet complexes. These sheet complexes consist of approximately 5m thick, laterally extensive "packets" of medium- to thick-bedded, massive sandstones with interbedded low concentration turbidites and siltstones. The thicker, massive sandstones are interpreted to have been deposited ravidlv - .from suspension by high concentration turbidity currents in an outer fan environment and represent the dominant facies type. Although the sandstone "packages" are highly continuous, lenticular and compensatory sandstone bedding styles and small scale scour surfaces are locally present. Loaded bedding contacts, flame structures and evidence for dewatering are abundant and indicate high rates of deposition. The bases of these sheet complexes are relatively sharp but tend to be nonerosional. They are either overlain by thinner siltstone dominated intervals or, where amalgamated, the base of a younger sandstone "packet". In the lower portion of the photograph the complexes appear to be compensationally stacked or laterally offset and are interbedded with siltstone intervals. In the middle to upper portions,

the complexes are thicker, more amrugamated and appear to be stacked in an aggradational fashion. Rather than reflecting overall progradation or outbuilding of fan systems, these vertical stacking patterns likely reflect lateral switching of depositional axes of systems through time.

5.lb This photograph shows a close-up view of complex bedding geometries within the lower member. Near the base of the outcrop a sandstone "packet" is observed to thin over an underlying "packet" that is seen to thin in the ouoosite direction. Like many of the sheet complexes, the "packet" thinning to the left exhibits an upward thickening bedding trend. This is due to successively younger beds pinching out progressively further to the left indicating a depositional response to underlying topography. The sandstone beds show an inter-fingering relationship with the adjacent siltstone interval rather than onlapping a single surface, and beds and laminae of the adjacent siltstone interval can be traced into the sandstone "packet". This suggests that many of the siltstone prone intervals interbedded with these deposits may be marginal or off-axis facies and not actual abandonment intervals, and underscores the difficulty in performing stacking pattern analyses at this scale. A A

..

0

,

3"; d

.

.

.,

Sheet Complex Axis

Figure 5.2. Amalgamated Sheet Complex (sheet axis): Cordoniz Canyon.

This is a depositional strike view of a sheet complex showing a lateral progression of increasing bedding amalgamation toward an axis (sheet axis). In many respects, the architecture of these layered sandbodies is very similar to the localized zones of amalgamation within the channel

margin sheets at Colleen Canyon. This complex shows similar axis to margin transitions in the degree of amalgamation; the sheet axis is dominated by amalgamated, normally graded, massive, fine-grained sandstones and the sheet-margin deposits are dominated by non-amalgamated,

massive, fme-grained sandstones. Finer grained interbeds present in the non-amalgamated margins are progressively removed by small scale erosion toward the axis. Complexes such as these are viewed as intermediate between the main channel complex at Colleen Canyon and

the layered sheet complexes seen on the previous page. They represent deposition within a transitional environment between confined and unconfined settings.

Figure 5.3. Summary of Outer Basin Floor Fan

Sheet Complex Characteristics Sandbody Geometry: Sharp based, extremely continuous, 5-7 m layered sandstone "packets" that are either compensationally stacked, laterally offset from one another, or stacked aggradationally. Internal Characteristics: Sheet complexes are dominated by medium- to thick-bedded, massive sandstones interbedded with minor low concentration turbidites and siltstones. Lenticular and compensatory internal sandstone bedding styles are common

and small scale scour surfaces are locally present. Loaded bedding contacts, flame structures and evidence for dewatering are common and indicate high rates of deposition. Sheet complexes also tend to display an aggradational to weakly developed thickening-upward organization. Based on the degree of vertical amalgamation, complexes are suhdivided into sheet axes and sheet margins and characterized as follows: Sheet axis: highly amalgamated, medium- to thick-bedded, massive, fine-grained sandstones; Sheet margin: thinner-bedded, non-amalgamated, massive, finegrained sandstones with interbedded siltstones.

Associated Facies: Thin siltstone intervals with minor, thin-bedded sandstones occur adjacent to and interbedded with sandstone dominated sheet complexes. In some cases these appear to be an offaxis or lateral facies association to the sandstone complexes.

Depositional Interpretation These sheet complexes are interpreted to have formed in an outer basin floor fan setting, but within a distributive depositional environment. The general lack of erosion and the extreme continuity of layered sandstone "packets" contain-

ing massive sandstones suggests suspension deposition in a relatively unconfined setting. However, the sheet axes or localized zones of amalgamation indicate focusing of flow and an association with nearby channels. The compensational stacking of sandstone "packets" indicates rapid changes in the position of depositional axes (e.g. lobe switching).

Acknowledgments The authors wish to thank Mr. Tony Kunitz for allowing geologic field studies to be conducted on the 6 Bar Ranch. A heartfelt thank you goes to Mike and Anne Capron. Their hospitality has always made us feel at home on the 6 Bar Ranch, and much of our work would not have been possible without their help. The cooperation of the U.S. National Park Scrvice is also acknowledged. The authors extend their thanks to Exxon Production Research Co. for allowing the release of this guidebook. In particular, we would like to thank C. R Jones, R. E. Hill, S. A. Reeckmann, S. M. Utskot, and W. T. Drennen 111. Without their cooperation, support, and guidance this guidebook and the field research conference would not have been possible. Many Exxon geoscientists have contributed to our understanding of the Brushy Canyon Formation during field excursions and training courses over the years. Their perspectives, insights and contributions to this work are respectfully acknowledged. The efforts of the members of the 1998 Deep-water Internship Program are gratefully acknowledged.

Extended Bibliography for Brushy Canyon Formation Armentrout, J.M., Peters, K.E., Sageman, B.B., Murphy, A.E. and Gardner, M.H., 1998, Stratigraphic Hierarchy of Organic Carbon-rich Siltstones in Deep-water Facies, Brushy Canyon Formation, (Guadalupian), Delaware Basin, Texas (abstr.); in AAPG International Meeting, Rio de Janeiro, Brazil, Extended Abstracts Volume, Mello, M.R. and Tilmaz, P.O. eds., p. 622-623. Beaubouef, R.T. and Rossen, C., 1999, Reconstructing Slope to Basin Floor Depositional Systems from Outcrop and Subsurface Data Sets; Examples of Sand-rich, Canyonfed Submarine Fan Complexes (abstr.), in AAPG Annual Convention, San Antonio, TX, Program with Abstracts, p. A10. Berg, R.R, 1979, Reservoir Sandstones of the Delaware Mountain Group, Southeast New Mexico; Guadalupian Delaware Mountain Group of West Texas and Southeast New Mexico, Permian Basin Section-Society of Economic Paleontologists and Mineralogists Publication, in Sullivan, N. M. ed., 79-18, p. 75-79. Bozanich, R.G., 1979, The Bell Canyon and Cherry Canyon Formations, Eastern Delaware Basin, Texas; in Guadalupian Delaware Mountain Group of West Texas and Southeast New Mexico, Permian Basin Section-Society of Economic Paleontologists and Mineralogists Publication, Sullivan, N. M. ed., 79-18, p. 121-141. Broadhead, R.F. and Luo, F., 1996, Oil and Gas Resources in the Delaware Mountain Group at the WIPP Site, Eddy County, New Mexico; in The Brushy Canyon Play in Outcrop and Subsurface, Permian Basin Section-Society of

Economic Paleontologists and Mineralogists Publication, DeMis, W.D. and Cole, A.G. eds., 96-38, p. 119-130.

Harms, J.C., 1968, Permian Deep-water Sedimentation by Non-turbid Currents, Guadalupe Mountains, Texas, Geological Society of America Special Paper 121, p. 127.

Fekete, T.E., 1986, The Sedimentology and Stratigraphy of the Grayburg Formation and Its Associated Erosion Surface along the High Western Escarpment of the Guadalupe Mountains, Texas; unpublished M.S. thesis, University of Wisconsin-Madison, 174 p.

Harms, J.C., 1974, Brushy Canyon Formation, Texas: A Deep-water Density Current Deposit, Geological Society of America Bulletin, 85, 1763-1784.

Franseen, E.K., 1985, Sedimentology of the Grayburg and Queen Formations (Guadalupian), and the Shelf Margin Erosion Surface, Western Escarpment, Guadalupe Mountains, West Texas; unpublished M.S. Thesis, University of Wisconsin-Madison, 189 p. Franseen, E.K., Fekete, T.E. and Pray, L.C., 1989, Evolution and Destruction of a Carbonate Bank at the Shelf Margin: Grayburg Formation (Permian), Western Escarpment, Guadalupe Mountains, Texas; in Controls on Carbonate Platform and Basin Development, Society of Economic Paleontologists and Mineralogists Special Publication, Crevello, P.D., Wilson, J.L., Sarg, J.F. and Read, J.F. eds., 44, p. 289-304. Fischer, A.G. and Sarnthein, M., 1988, Airborne Silts and Dune Derived Sands in the Permian of the Delaware Basin, Journal of Sedimentary Petrology, 58, p. 637-643. Gardner, M.H., 1992, Sequence Stratigraphy and Eolian Derived Turbidites: Patterns of Deep-water Sedimentation along an Arid Carbonate Platform, Permian (Guadalupian) Delaware Mountain Group, West Texas; in Permian Basin Exploration and Production Strategies: Applications of Sequence Stratigraphic and Reservoir Chararacterization Concepts: West Texas Geologic Society Publication, Murk, D.H. and Currans, B.C. eds., 92-9 1, p. 7- 12. Gardner, M.H., 1999, The Permian Brushy Canyon Formation Submarine Fan Complex of West Texas: Implications to Sequence Stratigraphic Models for Deepwater Clastics (abstr.), in AAPG Annual Convention, San Antonio, TX., Program with Abstracts, p. A45. Gardner, M.H. and Sonnenfeld, M.D., 1996, Recognition Criteria for Establishing a High Resolution Sequence Stratigraphic Framework for High Net-to-Gross Slope Sandstones, Permian Brushy Canyon Fm., TX (abstr.), in AAPG Annual Meeting, San Diego, CA., Program with Abstracts, p. A50. Gardner, M.H. and Sonnenfeld, M.D., 1996, Stratigraphic Changes in Facies Architecture of the Permian Brushy Canyon Formation in Guadalupe Mountains National Park, West Texas; in The Brushy Canyon play in outcrop and subsurface, Permian Basin Section-Society of Economic Paleontologists and Mineralogists Publication, DeMis, W.D. and Cole, A.G. eds., 96-38, p. 17-40.

Harms, J. C. and Pray, L. C., 1974, Erosion and Deposition along the Mid-Permian Intracratonic Basin Margin, Guadalupe Mountains, Texas; in Modern and Ancient Geosynclinal Sedimentation, Society of Economic Paleontologists and Mineralogists Special Publication, Dott, R. H. Jr. and Shaver, R. H. eds., 19, p. 37. Harms, J.C. and Williamson, 1988, rushy Canyon Formation, Texas: A Deep-water Density Current Deposit, Geologic Society of America Bulletin, 72, p. 287-3 17. Harms, J.C. and Brady, M.J., 1996, Deposition of the Brushy Canyon Formation: 30 years of Conflicting Hypotheses; in The Brushy Canyon Play in Outcrop and Subsurface, Permian Basin Section-Society of Economic Paleontologists and Mineralogists Publication, DeMis, W.D. and Cole, A.G. eds., 96-38, p. 51-61. Harris, M. T., 1982, Sedimentology of the Cutoff Formation (Permian), Western Guadalupe Mountains, West Texas and New Mexico; M.S. Thesis, University of Wisconsin-Madison, 186 p. Hills, J.M., 1942, Rhythm of the Permian Seas-A Paleogeographic Study, American Association of Petroleum Geologists Bulletin, 26, p. 217-255. Hull, J.P.D., 1957, Petrogenesis of Permian Delaware Mountain Sandstone, Texas and New Mexico, American Association of Petroleum Geologists Bulletin, 41, p. 278-307. Jacka, A.D., Beck, R.H., St. Germain, L.C., and Harrison, 1968, Permian Deep-sea Fans of the Delaware Mountain Group (Guadalupian), Delaware Basin; in Guadalupian facies, Apache Mountains area, West Texas, Permian Basin Section-Society of Economic Paleontologists and Mineralogists Publication, Silver, B. ed., 68-1 1, p. 49-90. Jacka, A.D., 1979, Deposition and Entrapment of Hydrocarbons in Bell Canyon and Cherry Canyon Deepsea Fans of the Delaware Basin; in Guadalupian Delaware Mountain Group of West Texas and southeast New Mexico, Permian Basin Section-Society of Economic Paleontologists and Mineralogists Publication, Sullivan, N. M. ed., 79-18, p. 104-120. Kane, T.V., 1992, Sequence Stratigraphy Improves Definition of Reservoir Architecture at Avalon (Delaware)

Field, Eddy County, New Mexico; in Permian Basin Exploration and Production Strategies: Applications of Sequence Stratigraphic and Reservoir Chararacterization Concepts, West Texas Geologic Society Publication, Murk, D.H., and Currans, B.C. eds., 92-91, p. 12-18. Kerans, C., Fitchen, W.M., Gardner, M.H., Sonnenfeld, M.D., Tinker, S.W. and Wardlaw, B.R., 1992, Styles of Sequence Development within Uppermost Leonardian through Guadalupian Strata of the Guadalupe Mountains, Texas and New Mexico; in Permian Basin Exploration and Production Strategies: Applications of Sequence Stratigraphic and Reservoir Characterization Concepts, West Texas Geologic Society Publication, Murk, D.H. and Currans, B.C. eds, 92-91, p. 1-6. Kerans, C. and Fitchen, W.M., 1995, Sequence Hierarchy and Facies Architecture of a Carbonate-ramp System: San Andres Formation of the Algerita Escarpment and Western Guadalupe Mountains, West Texas and New Mexico, The University of Texas Bureau of Economic Geology Report of Investigation 235, 86 p. Kerans, C. and Fitchen, W.M., 1996, Stratigraphic Constraints on the Origins of the Brushy Canyon Sandstones; in The Brushy Canyon Play in Outcrop and Subsurface, Permian Basin Section-Society of Economic Paleontologists and Mineralogists Publication, DeMis, W.D. and Cole, A.G. eds., 96-38, p. 61-69. King, P. B., 1942, Permian of West Texas and Southeast New Mexico, American Association of Petroleum Geologists Bulletin, 26, 535-763. King, P. B., 1948, Geology of the Southern Guadalupe Mountains, Texas. U. S. Geological Survey Professional Paper, 215, 183 p. King, P.B., 1965, Geology of the Sierra Diablo Region, Texas, U.S. Geologic Survey Professional Paper, 480, 185 p. Meissner, F.F., 1972, Cyclic Sedimentation in Middle Permian Strata of the Permian Basin; in Cyclic Sedimentation in the Permian Basin, West Texas Geological Society Publication, 72-60, p. 203-232. New, M., 1988, Sedimentology of the Cherry Canyon Tongue (Cherry Canyon Formation, Permian), Western Guadalupe Mountains, Texas and New Mexico; M.S. Thesis, University of Wisconsin-Madison, 285 p. Newell, N.D., Rigby, J.K., Fischer, A.G., Whiteman, A.J., Hickox, J.E. and Bradley, J.S., 1953, The Permian Reef Complex of the Guadalupe Mountains Region, Texas and . New Mexico, W.H. Freeman Co., San Francisco, 236 p.

Payne, M.W., 1976, Basinal Sandstone Facies, Delaware Basin, West Texas and Southeast New Mexico, American Association of Petroleum Geologists Bulletin, 60, p. 571-527. Ross, C. A., 1986, Paleozoic Evolution of Southern Margin of Permian Basin: Geological Society of America Bulletin, v. 97, p. 536-554. Ross, C. A. and Ross, J. R., 1985, Paleozoic Tectonics and Sedimentation in West Texas, Southern New Mexico, and Southern Arizona; in Structure and Tectonics of TransPecos, Texas: West Texas Geological Society Publication, Dickerson, P. W. and Muehlberger, W. R. eds., 85-81, p. 221-230. Rossen, C., 1985, Sedimentology of the Brushy Canyon Formation (Permian, Early Guadalupian) in the Onlap Area, Guadalupe Mountains, West Texas; M.S. Thesis, University of Wisconsin-Madison, 3 14 p. Rossen, C. and Sarg, J.F., 1988, Sedimentology and Regional Correlation of a Basinally Restricted Deep-water Wedge: Brushy Canyon-Cherry Canyon Tongue (Lower Guadalupian), Delaware Basin; in Guadalupe Mountains Revisited-Texas and New Mexico, West Texas Geological Society Publication, Reid, S.T., Bass, R.O. and Welch, P. eds., 88-84, p. 127-132. Rossen, C., Beaubouef, R.T. and Zelt, F.B., 1998, Slope to Basin Variations in Channel Geometry and Reservoir Architecture, Brushy Canyon Formation, Permian, West Texas (abstr.); in AAPG International Meeting, Rio de

Janeiro, Brazil, Extended Abstracts Volume, Mello, M.R., and Tilmaz, P.O. eds., p. 412.

AAPG Annual Meeting, San Diego, CA., Program with Abstracts, p. A50.

Ruggerio, R.W., 1985, Depositional History and Performance of a Bell Canyon Sandstone Reservoir, FordGeraldine Field, West Texas; unpublished M.S. Thesis, University of Texas, 242 p.

Silver, B. A. and Todd, R. G. 1969, Permian Cyclic Strata, Northern Midland and Delaware Basins, West Texas and Southeastern New Mexico, American Association of Petroleum Geologists Bulletin, 53, p. 2223-2225.

Sageman, B.B., Gardner, M.H., Armentrout, J.M. and Murphy, A.E., 1998, Stratigraphic Hierarchy of Organic Carbon-rich Siltstones in Deep-water Facies, Brushy Canyon Formation (Guadalupian), Delaware Basin, West Texas, Geology, 26, p. 451-454.

Wegner, M., Bohacs, K.M., Simo, J.A., Carroll, A.R. and Pevear, D., 1998, Siltstone Facies of the Upper Brushy Canyon and Lower Cherry Canyon Formations (Guadalupian), Delaware Basin, West Texas: Depositional Processes and Stratigraphic Distribution; in The Search Continues into the 21st Century: West Texas Geological Society, Publication, DeMis, W. D. and Nelis, M. K. eds., 98-105, p. 59-65.

Sarg, J. F. and Lehmann, P. J., 1986, Lower Middle Guadalupian Facies and Stratigraphy, San AndresIGrayburg Formations, Permian Basin, Guadalupe Mountains, New Mexico; in Lower and Middle Guadalupian Facies, Stratigraphy and Reservoir Geometries, San AndresIGrayburg Formations, Guadalupe Mountains, New Mexico and Texas, Permian Basin Section Society of Economic Paleontologists and Mineralogists Publication, Moore, G.E., and Welde, G.L. eds., 86-25, p. 1-5. Sarg, J. F., Rossen C., Lehmann, P. J. and Pray, L. C. eds., 1988, Geologic Guide to the Western Escarpment, Guadalupe Mountains, Texas. Permian Basin Section, Society of Economic Paleontologists and Mineralogists Publication, 88-30, 60 p. Sonnenfeld, M.D. and Gardner, M.H. 1996, Slope Discordance Cycles-Key to Erecting a Stratigraphic Hierarchy in Slope Systems: Middle Permian Brushy Canyon Formation, Guadalupe Mountains, TX (abstr.), in

Williamson, C.R., 1977, Deep-sea Channels of the Bell Canyon Formation (Guadalupian), Delaware Basin TexasNew Mexico; in Upper Guadalupian Facies, Permian Reef Complex, Guadalupe Mountains, Permian Basin Section, Society of Economic Paleontologists and Mineralogists Publication, Hilleman, M.E. and Mazullo, S.J. eds, 77-16, p. 49-64. Williamson, C.R., 1979, Deep-sea Sedimentation and Stratigraphic Traps, Bell Canyon Formation (Permian), Delaware Basin; in Guadalupian Delaware Mountain Group of West Texas and Southeast New Mexico, Permian Basin Section-Society of Economic Paleontologists and Mineralogists Publication, Sullivan, N. M. ed., 79-18, p. 39-74.

Williamson, C.R., 1980, Sedimentology of the Guadalupian Deep-water Clastic Facies, Delaware Basin, New Mexico and West Texas, New Mexico Geological Society Guidebook, 3 1st Field Conference, p. 195-204. Ye, Q. and Kerans, C., 1996, Reconstructing Permian Eustacy from 2-D Backstripping and Its Use in Forward Models; in The Brushy Canyon Play in Outcrop and Subsurface, Permian Basin Section-Society of Economic Paleontologists and Mineralogists Publication, DeMis, W.D. and Cole, A.G. eds., 96-38, p. 69-74. Zelt, F.B. and Rossen, C., 1993, Stratal Architecture of Deep-water Channels and Levees, Brushy Canyon Formation (Permian), West Texas (abstr.), in AAPG Annual Meeting, New Orleans, LA, Program with Abstracts, p. 205-206. Zelt, F.B., Rossen, C., and DeVries, M.B., 1994, Deepwater Depositional Environments of the Brushy Canyon Formation (Permian), Texas: Recognition Criteria and Stratal Architecture; in Submarine Fans and Turbidite Systems, Sequence Stratigraphy, Reservoir Architecture and Production Characteristics Gulf of Mexico and International, Proc. GCSEPM 15th Res. Conf., Weimer, P., Bouma, A.H. and Perkins, B.F. eds., p. 439-440. Zelt, F.B. and Rossen, C., 1995, Geometry and Continuity of Deep-water Sandstones and Siltstones, Brushy Canyon Formation (Permian), Delaware Mountains, Texas; in Atlas of Deep-water Environments-Architectural Style in Turbidite Systems, Pickering, K.T., Hiscott, R.N., Kenyon, N.H., Ricci Lucchi, F. and Smith, F. eds., Chapman and Hall, p. 176-183.

ISBN 0-89181-189-3