Composition, Clay Mineralogy, and Diagenesis 

of the Simpson Group (Middle Ordovician), 

Grady County, Oklahoma

U.S. GEOLOGICAL SURVEY BULLETIN 1866-H
AVAILABILITY OF BOOKS AND MAPS OF THE U.S. GEOLOGICAL SURVEY

Instructions on ordering publications of the U.S. Geological Survey, along with the last offerings, are given in the 

current-year issues of the monthly catalog "New Publications of the U.S. Geological Survey." Prices of available U.S. Geological 

Survey publications released prior to the current year are listed in the most recent annual "Price and Availability List." Publications 

that are listed in various U.S. Geological Survey catalogs (see back inside cover) but not listed in the most recent annual "Price 

and Availability List" are no longer available.

Prices of reports released to the open files are given in the listing "U.S. Geological Survey Open-File Reports." updated 

monthly, which is for sale in microfiche from the U.S. Geological Survey, Books and Open-File Reports Section. Federal Center. 

Box 25425, Denver. CO 80225. Reports released through the NTIS may be obtained by writing to the National Technical 

Information Service, U.S. Department of Commerce, Springfield, VA 22161; please include NTIS report number with inquiry.

Order U.S. Geological Survey publications by mail or over the counter from the offices given below.

BY MAIL 

Books

Professional Papers, Bulletins, Water-Supply Papers, 

Techniques of Water-Resources Investigations, Circulars, publications of general interest (such as leaflets, pamphlets, booklets), single copies of periodicals (Earthquakes & Volcanoes, 

Preliminary Determination of Epicenters), and some miscellaneous reports, including some of the foregoing series that have 

gone out of print at the Superintendent of Documents, are 

obtainable by mail from

U.S. Geological Survey, Books and Open-File Reports Section

Federal Center, Box 25425

Denver, CO 80225

Subscriptions to periodicals (Earthquakes & Volcanoes 

and Preliminary Determination of Epicenters) can be obtained 

ONLY from

Superintendent of Documents

U.S. Government Printing Office

Washington, DC 20402

(Check or money order must be payable to Superintendent 

of Documents.)

Maps

For maps, address mail orders to

U.S. Geological Survey, Map Distribution

Federal Center, Box 25286

Denver, CO 80225

Residents of Alaska may order maps from

U.S. Geological Survey, Map Distribution

New Federal Building - Box 12 

101 Twelfth Ave., Fairbanks, AK 99701

OVER THE COUNTER

Books

Books of the U.S. Geological Survey are available over 

the counter at the following U.S. Geological Survey offices, all 

of which are authorized agents of the Superintendent of Documents:

 ANCHORAGE, Alaska-4230 University Dr., Rm. 10]

 ANCHORAGE, Alaska-605 West 4th Ave.. Rm. G-84

 DENVER, Colorado-Federal Bldg., Rm. 169. 1961 Stout 

St.

 LOS ANGELES, California-Federal Bldg., Rm. 7638, 

300 North Los Angeles St.

 MENLO PARK, California-Bldg. 3, Rm. 3128, 345 Middlefield Rd.

 RESTON, Virginia National Center. Rm. IC402. 12201 

Sunrise Valley Dr.

 SALT LAKE CITY, Utah-Federal Bldg., Rm. 8105. 125 

South State St.

 SAN FRANCISCO, California-Customhouse. Rm. 504. 

555 Battery St.

 SPOKANE, Washington-U.S. Courthouse. Rm. 678, West 

920 Riverside Ave.

 WASHINGTON, DC U.S. Department of the Interior 

Bldg.. Rm. 2650, 1849 C St., NW.

Maps

Maps may be purchased over the counter at the U.S. 

Geological Survey offices where books are sold (all addresses in 

above list) and at the following U.S. Geological Survey offices:

 ROLLA, Missouri 1400 Independence Rd.

 FAIRBANKS, Alaska-New Federal Bldg.. 101 Twelfth 

Ave.
Chapter H

Composition, Clay Mineralogy, and Diagenesis 

of the Simpson Group (Middle Ordovician), 

Grady County, Oklahoma

By RICHARD M. POLLASTRO

A multidisciplinary approach to research studies of sedimentary 

rocks and their constituents and the evolution of sedimentary 

basins, both ancient and modern

U.S. GEOLOGICAL SURVEY BULLETIN 1866 

EVOLUTION OF SEDIMENTARY BASINS ANADARKO BASIN
U.S. DEPARTMENT OF THE INTERIOR 

MANUEL LUJAN, JR., Secretary

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director

Any use of trade, product, or firm names in this publication is for descriptive 

purposes only and does not imply endorsement by the U.S. Government.

UNITED STATES GOVERNMENT PRINTING OFFICE: 1991

For sale by the

Books and Open-File Reports Section

U.S. Geological Survey

Federal Center

Box 25425

Denver, CO 80225

Library of Congress Cataloging-in-Publication Data

Pollastro, Richard M.

Composition, clay mineralogy, and diagenesis of the Simpson Group (Middle 

Ordovician), Grady County, Oklahoma/ by Richard M. Pollastro.

p. cm. (Evolution of sedimentary basins Anadarko basin ; ch. H) 

(U.S. Geological Survey bulletin ; 1866H)

Includes bibliographical references, (p. ).

Supt. of Docs, no.: I 19.3:1866H

1. Sandstone Anadarko Basin. 2. Geology, Stratigraphic Ordovician. 

3. Geology Anadarko Basin. 4. Geology Oklahoma Grady County. 

I. Title. II. Series. III. Series: U.S. Geological Survey bulletin ; 1866H. 

QE75.B9 no. 1866-H 

[QE471.15.S25]

557.3 s dc20 91-2699 

[552'.5] CIP
CONTENTS

Abstract HI

Introduction HI

Geologic setting and stratigraphy H2

Methodology H3

Results and discussion H3

Whole-rock mineralogy H3 

Sandstone petrology H7

Composition and porosity H7 

Diagenesis H8 

Clay mineralogy H9

Clay diagenesis Hll

Formation of dolomite and ankerite cements HIS 

Summary HIS 

References cited H16

FIGURES

1. Map showing sedimentary rock thickness in greater Anadarko basin and location 

of Sunray DX, Parker No. 1, Mazur well, Grady County, Oklahoma H2

2. Chart showing stratigraphy of rocks of the Simpson Group and cored intervals 

studied in the Mazur well H3

3. Ternary diagram showing mineral composition and lithology for samples of the 

Simpson Group from the Mazur well H4

4. Partial ternary diagram showing composition of sandstones of the Simpson

Group from the Mazur well determined using point-count analysis H8 

5-6. Thin section photomicrographs of rocks of the Simpson Group from the Mazur 

well:

5. Sandstones from the Tulip Creek and Oil Creek Formations H10

6. Quartzarenites from the Tulip Creek and Bromide Formations Hll

7. Diagram showing paragenetic sequence for sandstones of the Simpson Group in 

the Mazur well H12

8. Scanning electron micrographs of sandstones of the Simpson Group from the 

Mazur well H12

9. Thin section photomicrographs of sandstones of the Simpson Group from the 

Mazur well H13

10. Scanning electron micrographs of sandstones of the Simpson Group from the 

Mazur well H13

11. Thin section photomicrographs of sandstones of the Simpson Group from the 

Mazur well H14

12. Typical X-ray powder diffraction profiles of rocks of the Simpson Group from 

the Mazur well HIS

13. Scanning electron micrographs showing morphology of rocks of the Simpson 

Group from the Mazur well H16

14. Diagramatic interpretation and thin section photomicrograph showing formation 

of authigenic dolomite and ankerite in deeply buried rocks of the Simpson 

Group from the Mazur well H17

Contents III
TABLES

1. Mineralogical data from X-ray powder diffraction for samples from the Mazur 

well H5

2. Range and mean whole-rock mineralogic composition for 36 samples of shale and 

50 samples of sandstone from the Mazur well H7

3. Comparison of average mineralogic composition of Simpson Group shale from the 

Mazur well and typical shale ana bentonite H8

4. Point-count compositional analysis of 32 thin sections of sandstone from the 

Mazur well H9

5. Average clay-mineral composition and range for 62 samples of shale and 

carbonate rocks and 50 samples of sandstone from the Simpson Group in the 

Mazur well H10

IV Contents
EVOLUTION OF SEDIMENTARY BASINS ANADARKO BASIN

Composition, Clay Mineralogy, and Diagenesis of the 

Simpson Group (Middle Ordovician), 

Grady County, Oklahoma

By Richard M. Pollastro

Abstract

Mineralogic and petrologic analyses were performed on 

more than 110 core samples of the Middle Ordovician Simpson Group in the Sunray DX, Parker No. 1, Mazur well, Grady 

County, Oklahoma. Core was recovered from present depths 

in the Anadarko basin of about 1 5,900-1 7,200 ft and includes 

(in descending order) all or parts of the Bromide, Tulip Creek, 

McLish, Oil Creek, and Joins Formations of the Simpson 

Group.

The whole-rock mineral composition of the samples is 

mainly related to varying lithology and degree of carbonate 

cementation. Most shale is clay rich and quartz poor, 

averaging about 85 percent clay minerals, 7 percent quartz, 

and 3 percent feldspar, by weight, as determined using X-ray 

powder diffraction. The high clay/quartz ratios suggest that 

much of the shale may have formed from either reworked, 

altered volcanic ash or that silica was expelled from shale by 

diagenetic processes during burial. Most sandstone is quartzarenite and some subfeldspathic arenite; quartz graywacke is 

also present. Little late silica cement is found in adjacent 

sandstones; however, early quartz overgrowth cement is 

ubiquitous in most sandstones. Excess silica from the alteration 

of glass to clay or expelled from shale during diagenesis and 

then transported updip in solution may have been a source for 

early silica cement in shallower sandstones.

Discrete illite and interstratified illite/smectite having low 

(<15 percent) expandability (R>1) are the main clay minerals. 

Iron-rich, authigenic chlorite cement is locally concentrated in 

some sandstones. Illite and illite/smectite commonly make up 

more than 90 relative weight percent of the clay minerals in 

sandstone and more than 95 relative weight percent of those in 

shale and carbonate rocks.

Manuscript approved for publication November 5, 1990.

Scanning electron microscopy reveals that much of the 

illite is diagenetic and is present as tabular fibers in pores or as 

pseudomorphic intergrowths after smectite. Illite is also 

present as overgrowths evident as sericitic cement in thin 

section examination. Most chlorite in sandstones is authigenic 

and is present as pore-lining cement or as pseudomorphic 

replacement after kaolinite. A clay-mineral assemblage consisting of illite, ordered illite/smectite (R>1), and chlorite and 

without smectite and kaolinite suggests that burial temperatures exceeded 150 °C. This interpretation is supported by 

burial- and thermal-history reconstructions for the Mazur well.

Carbonate cements are abundant throughout the entire 

Simpson sequence. Early iron-poor calcite cement is commonly replaced by iron-rich calcite, dolomite, or ankerite. 

Rhombic dolomite in sandstone and in carbonate rocks 

commonly has overgrowths of ferroan dolomite or ankerite. 

Cementation and (or) replacement by ankerite is later than 

calcite or iron-free dolomite and is generally less selective. 

Dolomite and ankerite cements commonly replace detrital 

clay and calcite. Spatial and textural relations suggest that the 

conversion of smectite to illite contributed, in part, to the 

formation of dolomite and ankerite cements.

Secondary porosity, formed mainly from the dissolution 

of intergranular carbonate cements, is best developed in 

sandstones from the Oil Creek and Tulip Creek Formations. 

Maximum porosity measured from point-count analysis is 11 

percent.

INTRODUCTION

An understanding of diagenesis is critical to any study 

in sedimentary basin analysis or petroleum geology. In 

particular, studies that relate effects of diagenesis to the 

quality of petroleum reservoir rocks and the maturity of 

potential source rocks are most critical (Scholle and 

Schluger, 1979; McDonald and Surdam, 1984; Gautier,

Middle Ordovician Simpson Group, Oklahoma H1
1986; Naeser and McCulloh, 1989; Surdam and others, 

1989).

Although commonly incomplete, a physical and 

chemical record of depositional and diagenetic conditions 

can be interpreted from mineralogic and petrologic studies 

of buried sedimentary rocks. The initial mineralogy and 

petrology of a potential reservoir rock have a strong 

influence on its reaction to postdepositional conditions. 

Therefore, a good understanding of the original detrital 

components allows a much better perspective for studying 

diagenesis. Numerous case history studies illustrate that 

potential reservoir rocks that have been deeply buried 

commonly have undergone several cementation and 

dissolution events. For example, petrographic data reported 

here and in Weber (1987) and Pitman and Burruss (1989) 

classify a large number of sandstones from the Simpson 

Group in the Mazur well as quartzarenite having a detrital 

framework composition of more than 95 volume percent 

quartz. Bulk compositions of these same sandstones, 

however, show that they contain as much as 45 volume 

percent authigenic constituents. Other studies refer to some 

of the sandstones as diagenetic quartzarenites in which 

detrital compositions have been modified extensively by 

diagenesis (McBride, 1987).

Clay minerals can also provide information on the 

geologic framework and diagenetic history of sedimentary 

rocks and basins. They are used as compositional, directional, and distance indicators relative to source terrains 

(Carson and Arcaro, 1983) and as environmental indicators 

of conditions during deposition and subsequent burial 

(Weaver, 1979; Hower, 1981). In some cases, systematic 

changes in clay minerals with progressive burial depth in a 

sedimentary basin can be used to predict the thermal history 

of the basin and, in many cases, provide information on the 

thermal maturity of source beds (Hoffman and Hower, 

1979; Weaver, 1979; Burtner and Warner, 1986; Pollastro 

and Barker, 1986; Pollastro and Scholle, 1986; Schoonmaker and others, 1986; Scotchman, 1987; Pollastro and 

Schmoker, 1989).

This report describes the mineralogic and petrologic 

composition and diagenesis of deeply buried rocks of the 

Simpson Group sampled from core in the Anadarko basin, 

Oklahoma. It presents data and interpretations to supplement those reported previously by Pollastro (1989a). 

Although samples of all rock types within the Simpson 

Group were analyzed for mineral composition, this report 

focuses on the petrography and diagenesis of sandstone and 

shale, in particular the nature, occurrence, and origin of clay 

minerals in these rocks.

Acknowledgments. I would like to thank Chris 

Schenk and Paula Hansley for their critical reviews and 

Judy Stoeser for editing of the manuscript. Their comments 

and suggestions greatly improved the final publication.

GEOLOGIC SETTING AND STRATIGRAPHY

The Anadarko basin of western Oklahoma, southwestern Kansas, and the northern part of the Texas Panhandle is one of the deepest Paleozoic basins in North 

America (fig. 1). In its deepest part sedimentary rocks are 

about 40,000 ft thick. The Anadarko basin contains 

numerous hydrocarbon-bearing intervals in both clastic and 

carbonate rocks. Thick, organic-rich shales of Devonian to 

Early Mississippian and Pennsylvanian age are the primary 

hydrocarbon source rocks for these reservoirs (Alder, 1971).

The Anadarko basin is markedly asymmetrical; its 

steep limb and axis are adjacent to, and parallel with, the 

northwest-trending Amarillo-Wichita uplift that borders the 

basin to the south; relatively stable shelf areas are to the 

north. The principal tectonic elements of the basin were 

formed during the Wichita orogeny from the late Morrowan 

through early Desmoinesian (Rascoe and Adler, 1983). As a 

result of concurrent growth and erosion of the AmarilloWichita Mountains from the Early Pennsylvanian to the 

Early Permian, pre-Pennsylvanian rocks were eroded and 

the sediments deposited in the basin as a terrigenous clastic 

wedge. The Arbuckle Mountains to the southeast were not 

formed until the Late Pennsylvanian. The thermal history of 

the Anadarko basin has been described in detail by 

Schmoker (1986).

The Simpson Group consists of five formations, as 

first proposed by Decker and Merritt (1931), and includes 

all rocks from the top of the Arbuckle Group to the base of 

the Viola Limestone (fig. 2). The five formations, in 

ascending stratigraphic order, are the Joins, Oil Creek, 

McLish, Tulip Creek, and Bromide. The Simpson Group is 

made up of sandstones, shales, and carbonate rocks, most of 

which were deposited in relatively shallow marine

Figure 1 . Sedimentary rock thickness in the greater Anadarko 

basin and location of Sunray DX, Parker No. 1, Mazur well, 

Grady County, Oklahoma (sec. 1, T. 3 N., R. 5 W.). Thickness 

contours are in feet. Heavy solid lines are faults.

H2 Evolution of Sedimentary Basins Anadarko Basin
2 

<

o

O

Q

oc 

O

Z>

O 

DC 

O

2 

0

SIMPS

i i i i i

, , ! , , ' , I {

=&iS?.z_^ 

::::::::o:::::::::::::::: : ::::::?)

 ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ; ' '

' ' -i. .i- ! '_'

 i i i i i 

1 . ' i ' ' ' i I , I ,

1 1 ' 1 ' 1 '1 

1 1 1 1 1 1 1 1

VIOLA LIMESTONE

BROMIDE FORMATION

TULIP CREEK FORMATION

McLISH FORMATION

 )

OIL CREEK FORMATION

JOINS FORMATION 

: ARBUCKLE GROUP (part)

Figure 2. Stratigraphy of rocks of the Simpson Group and 

cored intervals studied in the Mazur well. Modified from 

Johnson and others (1984).

environments (Longman, 1976; Lewis, 1982). Regional 

paleogeography and detailed lithofacies maps of the Simpson Group have been published by Schramm (1964).

METHODOLOGY

Approximately 110 samples of sandstone, shale, and 

carbonate were obtained from core of the Sunray DX, 

Parker No. 1, Mazur well, Grady County, Oklahoma (sec. 1, 

T. 3 N., R. 5 W.) (fig. 1). The cored intervals were 

recovered between present depths of about 15,900 and 

17,200 ft and include parts or all of each of the five 

formations of the Simpson Group (fig. 2).

Plugs, 1 in. in diameter, were taken from all rock 

types represented in the core. Half of each plug was 

prepared for X-ray powder diffraction (XRD) analysis; the 

other half was used for thin section analysis and scanning 

electron microscopy (SEM).

Samples for XRD were washed and scrubbed to 

remove surficial contaminants, dried, and then ground to 

<35 mesh. Each sample was then split using a Jones splitter 

into two portions for (1) whole-rock XRD and (2) carbonate 

dissolution and clay-mineral analysis. Carbonate was 

dissolved in IN HC1 and the residue filtered and washed 

immediately after effervescence stopped so as to minimize 

solution of noncarbonate minerals (Pollastro, 1977). The 

insoluble residue was dried overnight at 65 °C. The weight 

percent of the residue and (or) carbonate was then determined. A small part of the residue was spot-checked for 

undissolved carbonate using 6N HC1. For this study, 

carbonate rocks are defined as those containing 50 percent, 

by weight, or more carbonate minerals. Similarly, quartz 

sandstones are defined by XRD analysis as those containing 

50 percent or more quartz, and shale as those containing 50 

percent or more clay minerals.

Qualitative and semiquantitative estimates of the 

minerals in whole-rock samples were made using XRD 

analysis of randomly oriented powders that were ground to 

a maximum grain size of 44 j^m (<325 mesh) and packed 

from the back side into aluminum specimen holders. A fine 

random texture was imparted onto the surface to be 

irradiated in order to further disrupt any preferred orientation created while mounting the sample (see Schultz, 

1978). Semiquantitative weight percent values for total clay 

(phyllosilicates) and other minerals or mineral groups were 

calculated by comparison with several prepared mixtures of 

minerals having similar XRD characteristics using the 

procedures outlined by Schultz (1964) and Hoffman (1976) 

and modified by Pollastro (1985). The semiquantitative 

relative weight percent values calculated for total carbonate 

minerals by XRD were then compared with those determined using chemical dissolution.

Oriented clay aggregates of the <2-j.im and <0.25-j^m 

(equivalent spherical diameter) fractions were prepared 

using a modified filter-membrane-peel technique (Pollastro, 

1982) similar to that described by Drever (1973). Semiquantitative XRD analysis of the clay-sized fractions were made 

using the method of Schultz (1964) as modified by Pollastro 

(1985). Composition and ordering of interstratified illite/ 

smectite (I/S) clay was determined on oriented, ethylene 

glycol-saturated specimens of both the <2-j^m and <0.25- 

[im fractions using the methods of Reynolds and Hower 

(1970) and Reynolds (1980).

Thin sections were impregnated with blue epoxy to 

aid in recognizing porosity. Each section was then stained 

with potassium ferrocyanide and alizarin red for identification of carbonate phases (Dickson, 1966) and with 

potassium cobaltnitrite to distinguish potassium feldspar 

from plagioclase. Sandstone compositions were determined 

for thin sections based on a minimum of 300 counts and 

using the classification scheme of Pettijohn and others 

(1973) with some modification.

SEM and energy-dispersive chemical analyses were 

performed on samples of freshly fractured rock chips. Each 

sample was mounted on aluminum stubs, air dusted, and 

coated with about 100 angstroms of a gold-palladium 

mixture.

RESULTS AND DISCUSSION

Whole-Rock Mineralogy

The whole-rock compositions, as determined using 

XRD, for all samples are given in table 1. For simplification, the data are summarized in the ternary diagram 

of figure 3. The three end members of figure 3 quartz, 

total clay, and total carbonate represent the three major 

mineral groups in the rocks studied and, in this report,

Middle Ordovician Simpson Group, Oklahoma H3
CLAY

EXPLANATION

A Quartz sandstone

 Shale

 Carbonate 

n Mixed

-\50

CARBONATE

Figure 3. Ternary diagram showing mineral composition and 

lithology for samples of the Simpson Croup from the Mazur 

well. Data in weight percent of bulk rock determined using 

X-ray powder diffraction (XRD) analysis.

generally represent the pure end-member rock types quartz 

sandstone, shale, and carbonate rocks, respectively. Mineralogic compositions of Simpson Group rocks from the 

Mazur well are diverse and vary from almost pure endmember to mixed compositions.

Shale, as defined here using mineralogy, is composed 

predominantly (>50 percent by weight) of clay minerals 

(phyllosilicates). Table 2 lists the average and range in 

composition for shale and sandstone of the Simpson Group 

from the Mazur well. As shown in the data of table 2 and 

illustrated in figure 3, the three main components of rocks in 

the Mazur well are quartz, clay, and carbonate. Shale in the 

well is unusually clay rich and quartz poor relative to data 

reported elsewhere for shale. In particular, shales from the 

Bromide, Tulip Creek, and upper part of the McLish, to a 

present depth of 16,400 ft (interval 1 in table 2), have a 

mean composition of 84 percent clay and 7 percent quartz, 

by weight, as determined using XRD (table 1). Below this 

depth (interval 2), however, the Simpson Group shales 

contain more quartz and carbonate and have a mean 

composition of 62 percent clay, 15 percent quartz, and 13 

percent carbonate. In both intervals feldspar and pyrite 

make up the remaining portion.

No good mineralogic data were found in the literature 

for other shallow-buried Paleozoic shales in the Anadarko 

basin for comparison. Therefore, the Mazur well shale data 

are compared to the mineralogic data of Hosterman and 

Whitlow (1983) for Devonian shales and bentonites of the 

Appalachian basin and to data of Schultz ard others (1980) 

for Upper Cretaceous shales and bentonites of the Northern 

Great Plains (table 3). The data from Hosterman and 

Whitlow (1983) are from drill core and cuttings of Devonian shales, some of which have undergone significant 

burial diagenesis as evidenced by illite crystallinity and 

conodont color alteration indices. The data of Schultz and 

others (1980) from the Pierre Shale mainly represent

outcrop samples that have not been significantly modified 

by burial diagenesis; some samples, however, have been 

altered by local thermal events. Also, these Upper 

Cretaceous shales were derived mainly from freshly altered 

volcanic debris (Schultz and others, 1980). In contrast, a 

shale mostly derived from reworked older detritus typically 

contains more quartz and fewer clay minerals.

The high clay and low quartz values for shales of the 

Simpson Group suggest that these shales were either 

primarily derived from altered volcanic debris (mainly 

glass), similar to the marine shale and bentonite of the Pierre 

Shale, or that the composition of the shales was modified by 

burial; that is, a significant amount of silica was removed 

from the shales by diagenetic processes. Similar high 

clay/quartz ratios are characteristic of bentonites, potassium 

bentonites, or tonsteins (Schultz and others, 1980; Pollastro, 

1981; Hosterman and Whitlow, 1983; Pollastro and Martinez, 1-985; Pollastro and Pillmore, 1987). In addition, 

pyrite is common in shales of the Simpson from this study 

and may account for as much as 20 weight percent of the 

whole-rock samples (table 1). Pyrite formation has been 

related to rocks derived from volcanic material (Schultz and 

others, 1980; Pollastro, 1981; Pollastro and Scholle, 1986).

No discrete volcanic ash layers were found in the 

Mazur core. Although there is no direct evidence that 

mineral assemblages of most or all of the shales of the 

Simpson were mostly products of altered volcanic debris, 

the Middle Ordovician of North America was a time of 

extensive explosive volcanic activity (Samson and others, 

1989; Weaver, 1989) that presumably was related to Taconian orogenic activity. In eastern North America, at least 19 

separate ash beds (a few centimeters to 4 m thick) have been 

identified in Middle Ordovician carbonate rocks (Weaver, 

1989). Weaver (1989) stated that no discrete ash beds 

appear to have been preserved in the south-central region of 

North America; however, Middle Ordovician shales and 

limestones of Oklahoma and west Texas have a high I/S 

content. Weaver (fig. 9-1), using a compilation of clay 

mineral data for North American shales, showed that the 

amount of smectitic and chloride clay minerals significantly 

increased during the Ordovician. He interpreted these 

minerals as volcanic in origin.

The present mineralogy of the Simpson shales may 

have been modified to some extent by burial diagenetic 

processes; that is, silica was removed from the shales during 

deep burial reactions. This interpretation, however, presents 

a problem of balancing the silica budget in the adjacent 

sandstones or other rock types analyzed because there is no 

petrographic evidence for extensive late silica cementation 

in adjacent sandstones. The silica budget has also been 

addressed by Boles and Franks (1979), Houseknecht (1988), 

and others. Silica expelled from shales during deep burial 

diagenesis and transported updip in solution may have 

provided a source for much earlier silica cement in 

sandstones at shallower depths. The silica in shales could

H4 Evolution of Sedimentary Basins Anadarko Basin
Table 1 . Mineralogical data from X-ray powder diffraction for samples from the Mazur well

[In relative weight percent Samples designated by depth from surface in feet and inches; number before decimal point indicates feet and after 

indicates inches. Asterisk (*) after sample designation indicates a shale sample. Bromide 1 and Bromide 2 are upper and lower units, respectively, 

of Bromide Formation and'indicative of separate depositional cycles (Flores and Keighin, 1986). Sol carb, acid-soluble carbonate; Cal, calcite; 

Dol/Ank, dolomite and (or) ankerite; Flag, plagioclase; K-spar, potassium feldspar, I/S, illite/smectite; Kaol, kaolinite; Oil, chlorite; P, pyrite; F, 

fluorapatite; tr, trace; leaders (--), none detected; nd, not determined]

Whole-rock mineraloev

Sample 

designation

15917.3*

15923.3

15928.9

15935.9*

15947 A *J S ~ / 9S

15954.2

15954.6*

15956.10

15959.6

15966.1

15966.4*

15978.5

15986.9

15955.7

16004.0*

16016.2

16030.5*

16032.2

16038.6*

16042.0

16053.4

16067.10

16083.7

16097/98*

16109*

16112.3

16225.2

16225.4*

16230.6

16240.4

16251.0

16263.1

16273.4

16289.9

16297.5

16302.11

16316.9

16318.3*

16327.9

16328.4*

16328.11

16338.8

16354.2

16358.4*

16363.10

16364.5*

Formation

Bromide 1 ....

Bromide 1 . . . .

Bromide 1 . . . .

Bromide 1

Bromide 1 . , . .

Bromide 1 . . . .

Bromide 1 , , . .

Bromide 1 . . . .

Bromide 1 . . . .

Bromide 1 . . . .

Bromide 1

Bromide 1 . . . .

Bromide 1 . . . .

Bromide 1 ....

Bromide 1

Bromide 1 . . . .

Bromide 1 , Bromide 1 . . . .

Bromide 1

Bromide 2

Bromide 2 ....

Bromide 2

Bromide 2 ....

Bromide 2 , Bromide 2

Bromide 2 ....

Tulip Creek..

Tulip Creek..

Tulip Creek..

Tulip Creek..

Tulip Creek...

Tulip CreekTulip Creek..

Tulip Creek...

Tulip CreekTulip Creek...

Tulip Creek...

Tulip Creek...

Tulip Creek...

Tulip Creek..,

Tulip Creek...

Tulip Creek...

Tulip Creek..,

Tulip Creek..,

Tulip Creek..,

Tulip Creek..,

Sol 

carb

.13

.50

.19

24

54

.63

4

.24

.48

.18

2

.39

...9

.30

.36

.20

7

.16

4

.17

6

.71

....tr

....tr

.20

....tr

....7

.12

.18

.45

.85

.10

.76

....-

.55

.17

....9

....--

...A

....-

Clay

75

19

32

67

i i ao

28

80

14

13

34

86

31

5

13

84

5

89

10

92

2

8

18

35

83

88

14

4

86

15

14

7

13

13

11

20

21

6

82

58

10

16

14

80

4

86

Quartz

8

41

47

8

26

14

9

56

28

47

8

32

85

48

11

55

7

68

3

84

76

78

43

10

8

11

96

4

85

84

70

87

79

74

60

33

9

2

19

2

34

67

74

16

91

6

Cal

15

38

15

13

36

40

1

23

44

9

14

1

30

__

..

_

_

_

__

12

_

~

8

16

28

2

2

1

-

--

-

Dol/Ank

3

10

5

8

15

16

9

5

4

9

21

9

9

__

38

20

14

8

4

18

3

61

_

~

tr

tr

23

~

-

15

2

18

82

80

-

56

17

10

4

1

Plag

__

1

_

7

--

_

__

_

2

_

_

__

1

_

~

~

-

-

1

~

~

-

~

-

-

~

-

K-spar

3

2

3

4

3

~

5

1

5

3

3

_

_

3

3

2

_

5

tr

tr

tr

-

2

tr

_

4

-

-

tr

-

2

3

~

Other

3-P

2-P

1-P

2-P

2-P

1-P

4-P

2-P

1-P

1-P

1-P

__

2-P

1-P

1-P

2-P

_

_

1-P

-

_

5-P

--

-

~

-

_

4-P.8-F

-

12-P.28-F

-

--

1-P

-

<2-|jm clav mineraloev

Illite

49

31

27

33

41

40

39

33

32

51

46

42

51

28

45

47

44

28

63

10

50

40

43

31

65

34

36

63

56

49

46

41

49

83

58

61

78

58

79

56

80

75

52

84

35

76

l/s

49

66

62

62

52

56

54

59

63

44

48

53

34

41

45

44

46

37

25

12

43

58

50

57

27

59

3

29

2

13

10

30

44

17

31

37

21

41

21

44

20

25

30

13

35

22

Kaol

1

3

__

4

-

3

_

5

7

4

7

4

_.

-

-

-

-

-

-

-

-

-

~

--

-

-

-

-

-

Chl

1

3

10

3

6

4

4

8

5

5

3

5

15

31

11

9

5

35

5

78

7

2

3

5

4

6

61

7

42

39

44

29

7

~

11

2

1

1

~

~

-

-

18

2

29

2

have been removed by organic fluids generated during the 

maturation of kerogen because these acidic pore fluids 

precede the migration of hydrocarbons (MacGowan and

Surdam, 1988). Houseknecht (1988) suggested that silica 

for early quartz overgrowths may have been transported in 

solution from deeper sandstones of the Bromide and other

Middle Ordovician Simpson Group, Oklahoma H5
Table 1 . Continued

Whole-rock mineralogy

Sample 

designation

16366.6* 

16370.11 

16382.9 

16386.0* 

16396.7 

16402.0* 

16403.3 

16408.2 

16409.3* 

16418.11

16428.9 

16433.0* 

16441.2* 

16443.7 

16445.5* 

16453.0 

16458.3 

16464.10 

16472.8* 

16478.0*

16476.8 

16487.7 

16496,6 

16505.7 

16515.4 

16525.2 

16534.9 

16544.3

16551.10 

16553.5 

16554.0* 

16566.8 

16578.5 

16579.9 

16588.10 

16597.3 

16606.10 

16616.8

16624.6 

16626.8* 

16635.11 

16637.0* 

16640.0* 

16648.7 

17056.5* 

17057.4* 

17058.10 

17067.3

Formation

McLish....

McLish....

McLish....

McLish....

McLish....

McLish....

McLish....

McLish....

McLish....

McLish....

McLish....

McLish....

McLish....

McLish....

McLish....

McLish....

McLish....

McLish....

McLish....

McLish....

McLish....

McLish....,

McLish....,

McLish....

McLish....

McLish....

Oil Creek..

Oil Creek..

Oil Creek..

Oil Creek . .

Oil Creek . .

Oil Creek..

Oil Creek..

Oil Creek..

Oil Creek..

Oil Creek..

Oil Creek..

Oil Creek..

Oil Creek..

Oil Creek . . 

Oil Creek..

Oil Creek..

Oil Creek . . 

Oil Creek..

Oil Creek.. 

Oil Creek..

Sol 

carb

.....12

.....62

.......5

.....26

.....52

.....17

.....10

.......3

.......2

.....39

.....14

.....21

.....92

.....49

.......4

.....39

.....55

.....98

.....90

.....99

95

.....70

.....31

....55

....99

......5

....80

....54

....15

....34

....36

....52

......9

......tr

....18

....12 

..... .tr

......2

....13 

......6

....26 

....79

Clay

87 

10 

31 

81 

6 

86 

10 

32 

86 

13

13 

55 

72 

31 

50 

23 

5 

11 

62 

73

16 

33

6 

19

23

34 

tr 

77 

10

41 

14 

12 

12 

11

43 

70 

18 

72 

78 

7 

55 

76 

18 

19

Quartz

2 

78 

8 

7 

89 

5 

61 

9 

6 

68

60 

30 

14 

22 

29 

32 

1 

36 

3 

9

33 

10 

2 

5 

1 

2 

11 

36

6 

tr 

9 

15 

26 

33 

49 

46 

33 

70

55 

7 

61 

9 

12 

90 

24 

15 

50 

7

Cal

1 

31

2 

15 

36

5 

11

1 

34 

12 

25 

81 

23

2

30 

35 

97 

86 

84 

70 

39 

15

46 

95 

2 

72 

46 

8 

31 

25

3 

11 

2 

16 

70

Dol/Ank

1 

12 

30

5

14 

16

12

5 

3 

2 

5 

3 

5 

13 

30

2

13 

15 

1 

6 

15 

22 

28 

16

9 

4 

5 

3 

11 

8 

6 

17 

55 

11

tr

21 

10 

2

3 

2 

15 

2

Flag

2

2

2 

2

1

2 

7

3 

2

3 

3

2 

1

8

2 

1

K-spar

5

5 

5

5 

4 

2

10 

10 

7 

4 

2 

8

26 

9

2 

4

3

3 

8

2 

5

9 

9

2

5 

5

2 

3

Other

2-P

1-P 

2-P

2-P

2-P 

2-P 

2-P 

1-P

5-P 

3-P

3-P

2-P 

2-P

1-P

20-P

4-P 

3-P

3-P 

3-P

2-P

<2-u,m clay mineralogy

Illite

77 

88 

49 

71 

16 

86 

59 

58 

83 

59

65 

63 

61 

52 

69 

54 

63 

92 

70 

60

66 

61 

31 

50 

47 

29 

57 

54

48 

24 

80 

69 

nd 

53 

33 

70 

56 

87

52 

76 

42 

78 

80 

77 

59 

59 

39 

18

1/5

22 

12 

42 

29 

2 

12 

13 

37 

16 

28

25 

29 

38 

40 

28 

36 

33 

8 

30 

37

25 

35 

63 

48 

47 

69 

40 

38

51 

69 

20 

31 

nd 

41 

67 

30 

44 

12

36 

18 

31 

19 

17 

17 

36 

37 

53 

78

Kaol Chl

2 

9

82 

2 

29 

4 

2 

13

10 

8 

2 

7 

3 

10 

3

3

9 

4 

6 

3 

6

3 

8

1 

7

nd nd 

3

2

11 

5

27

4

3 

5 

5 

4 

8 

4

formations; he proposed, however, that the silica was 

derived from pressure solution of quartz grains.

Early quartz cement is pervasive in most sandstones 

of the Simpson of this study. Increased volcanic activity 

during the Middle Ordovician favored early quartz cementation because silica is released during the relatively rapid

alteration of volcanic glass to clay, and both mineralogic 

and diagenetic evidence from the shale samples in the 

Mazur core favored some increased volcanic activity during 

Simpson deposition. This interpretation differs from that 

reported earlier by Pollastro (1989a). It is likely that both 

volcanic source material and diagenetic reactions involving

H6 Evolution of Sedimentary Basins Anadarko Basin
Table 1. Continued

Whole-rock mineralogy

Sample 

designation

17076.8 

17083.1* 

17086.3 

17099.2 

17106.7 

17115.0 

17115.8 

17116.2 

17130.3 

17136.3

17147.1 

17159.11 

17172.7

17182.10 

17184.6* 

17184.9 

17190.10 

17217.5

Formation

Oil Creek..

Oil Creek..

Oil Creek..

Oil Creek..

Oil Creek..

Oil Creek..

Oil Creek..

Oil Creek . .

Oil Creek..

Oil Creek..,

Oil Creek..,

Oil Creek...

Oil Creek..,

Joins .......

Joins .......

Joins .......

Joins.......

Joins .......

Sol 

carb

....79

....25

....73

....54

....82

....67

....37

....49

....10

......7

....20

...... tr

,.....tr

....20

....14

....22

....76

....44

Clay

18 

52 

17 

10 

4 

28 

38 

5 

5 

8

4 

5 

8

8 

55 

5 

22 

41

Quartz

52 

15 

11 

32 

13 

7 

18 

42 

83 

82

75 

93 

82

72 

23 

71 

5 

10

Cal

15 

8 

53 

44 

71 

32 

6 

27 

1

2

6

23 

4 

25

Dol/Ank

10 

17 

17 

11 

14 

27 

30 

24 

11 

10

21

20 

9 

1 

67 

17

Flag

2 

2

2 

1

K-spar

2 

3

4 

3

4

2 

3

Other

3-P 

4-P

2-P 

2-P

3-P 

3-P

<2-\im clay mineralogy

Illitc

49 

50 

39 

46 

48 

64 

73 

65 

69 

nd

84 

73 

77

88 

68 

nd 

48 

52

I/S

42 

49 

53 

51 

50 

34 

26 

35 

31 

nd

16 

27 

23

12 

31 

nd 

50 

46

Kaol Chl

9 

2 

9 

4 

3 

2 

1

nd nd

1

nd nd 

2 

2

Table 2. Range and mean whole-rock mineralogic 

composition for 36 samples of shale and 50 samples of 

sandstone from the Mazur well

[Determined using X-ray powder diffraction in weight percent of 

whole rock. Shale interval 1 refers to Bromide, Tulip Creek, and 

upper part of McLish Formations to core depth of 16,400 ft, interval 

2 includes Simpson Group shales between 16,400 and 17,400 ft]

Shale 

Interval 1 Interval 2 

Range Mean Range Mean

Quartz ......

Clay........

Carbonate. 

Feldspar.... 

Pyrite.......

..2-11

..58-92

...0-21 

...0-7 

...0-14

7 

84 

3 

4 

3

3-33 

41-78 

0-42 

0-27 

1-20

15 

62 

13 

6 

4

Sandstone 

Range Mean

50-96 

2-35 

0-48 

0-15 

0-3

66

14 

18 

2 

<1

transportation of silica may have produced the present 

mineralogy of shales of the Simpson Group from the Mazur 

well.

The whole-rock XRD mineralogical compositions of 

50 sandstone samples from the Simpson Group in the Mazur 

well are also summarized in table 1. Sandstones average 66 

percent quartz, by weight; some sandstones from the Oil 

Creek and Tulip Creek Formations contain as much as 96 

percent quartz. All sandstone samples, other than a few 

almost pure ones, contain appreciable clay and carbonate 

minerals, averaging 14 and 18 weight percent, respectively. 

Feldspar content is about 2 weight percent and pyrite less 

than 1 percent. The whole-rock XRD data are in close 

agreement with thin section point counts of this report (see 

following section) and with data for the McLish Formation 

reported by Weber (1987).

Sandstone Petrology

Composition and Porosity

Point-count analysis for 32 sandstone samples is 

summarized in table 4; framework compositions are plotted 

on the quartz feldspar rock fragments ternary diagram of 

figure 4. Most sandstones are quartzarenite; some subfeldspathic arenites are in the Tulip Creek and Mclish Formations and one sandstone from the Tulip Creek Formation is 

a sublithic arenite. Sandstones are composed mainly of 

detrital monocrystalline quartz grains (fig. 5A) and generally less than 5 percent feldspar, most of which is 

potassium feldspar (fig. 5B). Three sandstones, two from 

the Oil Creek and one from the Bromide, are graywackes 

(fig. 5C).

Lithic framework grains are principally shale clasts 

that are sometimes partly dissolved (fig. 5D). Carbonate 

clasts and shell fragments are present in a few samples; 

chert is extremely rare. Petrographic analysis indicates that 

most sandstones are mineralogically mature to supermature.

Most sandstones contain little or no porosity. All 

porosity observed in thin section is secondary (dissolution) 

porosity and is best developed in the Tulip Creek and Oil 

Creek Formations. Sandstones of these formations contain 

as much as 11 percent porosity, mainly secondary and 

intergranular, as determined from point-count analysis 

(figs. 55 and 6A). Minus-cement porosity determined from 

point-count analysis is commonly high (figs. 6B and C) and 

in some cases exceeds 40 percent. Some intragranular 

(moldic) porosity is also present (fig. 5D). Secondary 

intergranular porosity is mainly from the dissolution of

Middle Ordovician Simpson Group, Oklahoma H7
Table 3. Comparison of average mineralogic composition of Simpson Group shale from the Mazur well and 

typical shale and bentonite 

[Values in weight percent of bulk rock]

Simpson Group 

shale1

Quartz....................

Carbonate minerals....

Other.....................

....11

....74

.....7

4

......3

fj

Cretaceous shalez 

Marine Nonmarine

22 

68 

2 

5 

3

25 

61 

7 

7 

Minor

Cretaceous 

bentonite3

2 

83 

3 

4 

Minor

Devonian 

shale4

23 

66 

8 

Minor 

3

Devonian 

potassium 

bentonite5

10 

83 

1

2 

4

Determined using X-ray powder diffraction.

Data from Schultz and others (1980) for 366 samples of "ordinary shale" of the Pierre Shale and equivalent rocks, Northern 

Great Plains.

o

Data from Schultz and others (1980) for 119 samples of marine bentonite of the Pierre Shale and equivalent rocks, Northern 

Great Plains.

4Data from Hosterman and Whitlow (1983) for about 1800 samples of Devonian shale from drill core and cuttings (0-14,500 ft), 

Appalachian basin.

Data from Hosterman and Whitlow (1983) for 9 samples of ash beds of Devonian shale from drill core and cuttings (675-7,500 

ft), Appalachian basin.

carbonate cements, as evidenced by irregular and etched 

quartz framework grains and small remnants of earlier 

intergranular carbonate cement (figs. 5B and 6A). The shape 

and oversize of intergranular areas containing carbonate 

cement and the high percentage of carbonate in some of the 

sandstones (figs. 5A, 9A, B) suggest that labile grains such 

as plagioclase or rock fragments once occupied some of 

these spaces. Thus, these sandstones may not have been as 

quartz rich as they are today.

QUARTZ EXPLANATION

 Bromide Formation

 Tulip Creek Formation 

o Oil Creek Formation 

A Joins Formation 

x McLish Formation

ROCK FRAGMENTS

Figure 4. Partial ternary diagram showing composition of 

sandstones of the Simpson Group from the Mazur well 

determined using point-count analysis (minimum 300 counts). 

Sandstone classification scheme modified from Pettijohn and 

others (1973).

Diagenesis

The paragenetic sequence interpreted for sandstones 

of the Simpson Group in the Mazur well is shown in figure 

7. It should be noted, however, that the extent of diagenesis 

varies from one sandstone to another. Many of the diagenetic stages interpreted here are similar to those reported 

by Weber (1987), Pitman and Burruss (1989), and Pollastro 

(1989a). Although the relative timing of each event is 

shown in figure 7, the diagenesis in these sandstones can be 

grouped into three stages: early, intermediate, and late.

Early diagenesis is characterized by the formation of 

framboidal pyrite (fig. 8A), dissolution of labile grains 

(probably plagioclase and rock fragments, fig. 5D), and 

cementation by iron-poor calcite (fig. 65) or syntaxial 

quartz overgrowths (figs. 6C, D, 85). Criteria for the 

dissolution of labile grains include oversize pores now 

filled with calcite and some floating grains (figs. 5A and 

65). Although cementation by calcite and quartz is believed 

to have occurred relatively early in the burial history, grain 

contacts average about three per grain. This criteria and the 

presence of longitudinal- and interpenetrative-grain contacts 

(figs. 5A and 6C) suggest that at least 3,300 ft of burial 

occurred before cementation (Taylor, 1950; Pettijohn, 

1975).

Intermediate events include the dissolution and (or) 

replacement of clay as matrix or rock fragments, conversion 

of smectite to illite, overgrowths on potassium feldspar 

grains, replacement or conversion of iron-poor calcite to 

iron-rich calcite, dissolution of calcite cements, and formation of dolomite cement. Iron-rich calcite commonly 

replaces or encompasses earlier iron-poor calcite, as 

evidenced from stained thin sections (fig. 9A). Iron-rich 

carbonate cements formed after quartz overgrowths (fig. 

95). Dissolution of intergranular calcite cements commonly

H8 Evolution of Sedimentary Basins Anadarko Basin
Table 4. Point-count compositional analysis of 32 thin sections of sandstone from the Mazur well

[Data based on a minimum of 300 counts per section. Framework components in percent of total framework content; pores and pore fillers in

percent of total rock. Depth designation in feet.inches. see table 1]

Framework components Pores and pore fillers

Depth Formation Quartz Feldspar Rock fragments Matrix Cement Porosity

15,928.9 Bromide.................... 96

15,956.10 Bromide.................... 97

15,986.9 Bromide...................100

16,042.0 Bromide.................... 97

16,053.4 Bromide.................... 99

16,067.10 Bromide....................97

16,225.2 Tulip Creek................ 99

16,230.6 Tulip Creek................99

16,240.4 Tulip Creek................97

16,251.0 Tulip Creek................98

16,263.0 Tulip Creek...............100

16,273.4 Tulip Creek................99

16,289.9 Tulip Creek................99

16,297.5 Tulip Creek................97

16,302.11 Tulip Creek................92

16,338.8 Tulip Creek...............100

16,354.2 Tulip Creek................86

16,363.10 Tulip Creek................93

16,370.11 McLish.....................99

16,403.11 McLish....................100

16,418.11 McLish..................... 98

16,428.9 McLish.....................80

16,616.8 Oil Creek..................98

16,624.6 Oil Creek..................99

16,635.11 Oil Creek.................100

16,648.7 Oil Creek..................99

17,058.10 Oil Creek.................100

17,130.3 Oil Creek..................99

17,136.3 Oil Creek..................98

17,147.1 Oil Creek..................99

17,159.11 Oil Creek..................97

17,172.7 Oil Creek.................100

17,182.0 Joins.......................99

17,184.9 Joins......................100

0

1

0

1

0

0

1

1

3

2

0

1

1

2

7

0

5

5

1

0

2

20

2

1

0

1

0

1

2

1

3

0

1

0

16

3

0

0

0

1

0

0

0

0

0

1

0

5

6

1

1

1

1

5

5

2

5

29

9

2

19

0

0

0

0

0

0

0

18

28

22

21

26

13

6

4

6

20

14

24

22

28

40

28

21

19

29

33

33

18

31

<1

22

6

28

29

17

39

12

27

15

11 

8 

0 

3 

1 

0 

0 

0

<1 

1

created secondary porosity (fig. 5B). In many sandstones 

potassium feldspar overgrowths developed on detrital potassium feldspar grains (figs. 5D and 9C). The potassium for 

overgrowth cement may have come from dissolved or 

replaced potassium feldspar in adjacent sandstones (fig. 

6A), local potassium-bearing matrix clay (fig. 9C), or clayrich rock fragments (fig. 5D) that were dissolved or 

replaced. Illitization of smectite begins during intermediate 

stages of burial when temperatures approach 60 °C (Hoffman and Hower, 1979). Pore-lining or grain-coating chlorite 

was also precipitated during intermediate stages of burial 

in sandstones lacking early quartz or calcite cements 

(fig. 1(M).

Late diagenetic events include the formation of ferroan dolomite and ankerite (fig. 9D) and some quartz 

cement, some dissolution of iron-bearing carbonate minerals, progressive illite growth or sericitization of earlier I/S

(fig. 11A) (Pollastro, 1989b), and conversion of kaolinite to 

chlorite. These events will be discussed in later sections of 

this report. The formation of these later diagenetic phases is 

consistent with the diagenetic model proposed by Surdam 

and others (1989), for which burial temperatures exceeded 

120 °C.

Clay Mineralogy

The clay mineralogy of sandstones and shales from 

the Mazur well is summarized in table 5; quantitative clay 

analysis of the <2-jam fraction for individual samples is 

given in table 1. Carbonate rocks have a clay-mineral 

assemblage similar to that of shale. The dominant clay 

mineral is illite (as defined below); authigenic iron-rich 

chlorite is locally concentrated in sandstone. Minor to trace

Middle Ordovician Simpson Croup, Oklahoma H9
Table 5. Average clay-mineral composition and range for 

62 samples of shale and carbonate rocks and 50 samples 

of sandstone from the Simpson Group in the Mazur well 

[Values in relative weight percent of clay minerals in<2-{im fraction. 

l/S indicates ordered illite/smeclile]

Shale and carbonate 

Mean Range

Illite 

(illite + VS)....

Kaolinite.........

.....96

........4

88-100 

0-11 

0-7

Sandstone

Mean

85 

15

Range

18-100 

0-82 

0-4

amounts of kaolinite are present in some samples above 

16,300 ft; kaolinite is absent below this depth.

Almost all samples contain more than 90 percent 

illitic clay minerals in the <2-|im fraction. Illitic clay 

minerals include both discrete illite (10 angstrom) and I/S. 

All I/S in rocks of the Simpson Group from the Mazur well

is regularly interstratified I/S (R>1), and most samples 

contain only I/S with R>3 (<15 percent expandable layers) 

(fig. 12), as defined by XRD profiles using the XRD 

interpretive methods of Reynolds and Hower (1970). 

Following the concept of fundamental particles and interparticle diffraction (Nadeau and others, 1984a, b, 1985), 

however, ordered I/S is defined here as "thin" illite crystals 

20-50 angstroms thick (apparent I/S in fig. 12). I/S clay in 

table 1 was, therefore, recalculated as "illite" (illite=discrete 

illite and I/S) in the data of table 5.

The average clay-mineral composition of shale and 

carbonate rocks from the Mazur well is about 96 relative 

weight percent illite and 4 percent chlorite, as determined 

using XRD (table 4). The chlorite in shale probably reflects 

a relatively constant, but minor, influx of detrital chlorite.

The average clay-mineral composition of sandstone 

from the Mazur well is 85 percent illite and 15 percent

B

Figure 5. Thin section photomicrographs of sandstones of the Simpson Group from the Mazur well. Scale bars are 0.2 mm. A, 

Monocrystalline quartz (Q) grains in calcite-cemented (C) sandstone. Tulip Creek Formation, 16,251 ft; crossed nicols. B, Blueepoxy-impregnated sandstone showing remnants of carbonate (C) cement and detrital potassium feldspar (KF) grains. Tulip Creek 

Formation, 16,240 ft. C, Quartz (Q) wacke and interstitial clay (Cl). Oil Creek Formation, 16,624 ft. D, Sublithic arenite showing 

intragranular porosity (P) from the dissolution of shale clasts. Note overgrowths (OG) on detrital potassium feldspar (KF) grains. 

Tulip Creek Formation, 16,354 ft.

H10 Evolution of Sedimentary Basins Anadarko Basin
Figure 6. Thin section photomicrographs of quartzarenites of the Simpson Group from the Mazur well. Scale bars are 0.2 mm. 

A, Blue-epoxy-impregnated sandstone showing intergranular porosity (P) and etched surfaces (arrows) of quartz framework grains 

that probably are the result of dissolution of an earlier intergranular carbonate cement. Tulip Creek Formation, 16,230 ft. B, High 

minus-cement porosity in sandstone cemented by iron-free calcite (C). Bromide Formation, 15,929 ft. C, Quartz-cemented 

sandstone showing extensive overgrowths (arrows) on detrital quartz (Q) grains. Tulip Creek Formation, 16,264 ft. D, Detrital 

quartz (Q) grain showing well-defined dust rim (arrows) and extensive overgrowths (OC). Bromide Formation, 16,042 ft; crossed 

nicols.

chlorite. Local concentrations of authigenic iron-rich chlorite may account for as much as 82 percent of the clay 

minerals in the <2-jam fraction (table 1), but many samples 

contain little or no chlorite.

Clay Diagenesis

Clay minerals in these deeply buried rocks of the 

Simpson Group are essentially illite, apparent I/S (R>1), 

and chlorite. Kaolinite is present in only minor amounts. 

There is a distinct absence or disappearance of kaolinite 

below about 16,300 ft in the well. The present clay 

mineralogy of the Simpson Group in the Mazur well is 

consistent with an assemblage that is mostly the result of 

deep burial diagenesis. Further evidence for this interpretation is provided by XRD and SEM analyses and 

burial-history reconstructions.

The major clay-mineral reaction that occurs during 

the progressive burial of sedimentary rocks is the conversion of smectite to illite (Hower, 1981), a reaction 

illustrated and partly reinterpreted by Pollastro (1985, 

p. 273, fig. 8). Smectite (or smectite layers in I/S) in 

sediment or rock at near-surface or shallow-burial conditions is converted to illite (or illite layers in I/S) under 

increased temperature (>60 °C) and pressure (?) due to burial 

depth (Hower and others, 1976). Boles and Franks (1979) 

and Pollastro (1983, 1985) proposed that the reaction 

involves, in part, the dissolution of smectite, conservation of 

aluminum and potassium, and precipitation of illite. 

Calcium, silica, iron, and magnesium are released from 

smectite in the reaction. These elemental reaction products 

combine to form, at least in part, authigenic mineral phases 

in pores or fractures of deeply buried rocks. Typical phases 

that may form include dolomite, fine-grained quartz or

Middle Ordovician Simpson Group, Oklahoma H11
DIAGENETIC STAGE EarlyBURIAL HISTORY 

 ^Middle -> Late

Pyrite formation

Labile grain dissolution

Quartz cement

Calcite cement

Potassium feldspar overgrowths

Calcite to iron calcite

Smectite to illite

Clay matrix dissolution and replacement

Iron dolomite and ankerite

Chlorite cement

Illite overgrowths and sericitization

Grain dissolution

Kaolinite to chlorite

Figure 7. Paragenetic sequence for sandstones of the Simpson Croup in the Mazur well.

Figure 8. Scanning electron micrographs of sandstones of the Simpson Croup from the Mazur well. Scale bars are 10 um. 

A, Authigenic framboidal pyrite (P) in sandstone. B, Overgrowth (OC) cement on detrital quartz grains in quartzarenite.

quartz overgrowth cement, chlorite, and illite cement or 

overgrowths (Boles and Franks, 1979; McHargue and Price, 

1982; Pollastro, 1985). In open systems, however, these 

elements may leave the system completely and not necessarily result in the immediate in situ precipitation of 

authigenic minerals.

XRD profiles interpreted using the interparticle diffraction concept indicate that no true smectite is present in 

the Simpson Group rocks from the Mazur well. In addition, 

morphological evidence from SEM observations suggests 

that any earlier smectite-bearing clay has been converted to 

illite. This is evidenced by textures similar to those

described by Pollastro (1985) from SEM analysis in which 

intergrowths and overgrowths of tabular fibers of illite are 

superimposed within or on a honeycomb or cornflake 

morphology. Such textures suggest that an earlier smectiterich clay was recrystallized during diagenesis and converted 

to illite.

Sandstone from the Mazur well commonly contains 

authigenic illitic clay cements. Many of these cements were 

precipitated as illite late in the burial history; however, some 

of the cement was probably once smectitic and later 

converted to illite under relatively deep burial conditions. 

Figure 13A shows a scanning electron micrograph of a clay

HI 2 Evolution of Sedimentary Basins Anadarko Basin
D

Figure 9. Thin section photomicrographs of sandstones of the Simpson Croup from the Mazur well. Scale bars are 0.2 mm. 

A, Iron-rich (Fe) calcite encompassing or replacing earlier iron-poor (C) calcite. Tulip Creek Formation, 16,273 ft. B, Overgrowth cement (OC) on detrital quartz (Q) grains interpreted to have formed prior to iron-rich calcite (Fe) cement. Tulip Creek 

Formation, 16,251 ft. C, Stained overgrowths (OC) of potassium feldspar on detrital potassium feldspar (KF) grain. McLish 

Formation, 16,433 ft. D, Ankerite (A) cement replacing quartz (Q) framework grains, cement, and clay. Bromide Formation, 

16,016 ft.

Figure 10. Scanning electron micrographs of sandstones of the Simpson Croup from the Mazur well. Scale bars are 10 [im. 

A, Authigenic pore-lining chlorite (Ch) in sandstone. B, Dolomite (D) replacing detrital clay (Cl) in sandstone.

Middle Ordovician Simpson Croup, Oklahoma H13
Ch

Q

EL

Figure 11. Thin section photomicrographs of sandstones of the Simpson Croup from the Mazur well. Scale bars are 0.2 mm. 

A, Sericitic (S) clay cement. Tulip Creek Formation, 16,297 ft; crossed nicols. B, Pore-filling pseudomorphs of chlorite (Ch) after 

kaolinite. Q, quartz. Bromide Formation, 16,083 ft. C, Dolomite (D) rhombs and darker stained ankerite (A) overgrowths. Tulip 

Creek Formation, 16,290 ft. D, Dolomite (D) replacing clay (Cl) in sandstone. Bromide Formation, 15,966 ft.

cement in a sandstone of the Bromide Formation at about 

16,000 ft. The overall texture of the clay cement is a 

honeycomb or cornflake morphology that is typical of 

smectite. A high-magnification SEM image of the cement 

(fig. 135) shows that the honeycomb- or cornflake-like 

surfaces have a finer intergrowth fabric of interwoven 

tabular fibers that is characteristic of illite. It is proposed 

here that illite is a pseudomorphic intergrowth after smectite. In addition, subsequent overgrowths of tabular illite 

fibers are superimposed on the edges of the honeycombs 

(figs. ISA and B). Similar morphology and texture observed 

in shale (fig. 13C) suggest some recrystallization of a 

smectite-rich precursor to the present illite composition.

Iron-rich chlorite is the dominant clay mineral in six 

sandstone samples and a minor component in most. Diagenetic iron-rich chlorite is present in two forms. More 

commonly, it is a pore-lining clay cement that was 

precipitated directly from pore fluids; it coats framework 

grains and is present as characteristic pseudohexagonal or

ragged-edged, thin, clay plates forming an overall "house of 

cards" or rosette structure (fig. 10A). It also is a pseudomorphic replacement after pore-filling, vermicular kaolinite 

(figs. 1 IB and 13£>). The chemistry of iron chlorite pseudomorphs was confirmed by energy-dispersive X-ray analysis. 

Typically, kaolinite is precipitated from pore fluids 

during or immediately following carbonate dissolution 

(Lindquist, 1978; Loucks and others, 1979; Pollastro, 

1989b; Surdam and others, 1989). Based on the spatial and 

textural relations observed in this study and the common 

paragenetic sequences reported elsewhere for sandstone, 

kaolinite was probably precipitated as a pore-filling clay at 

the same time an earlier pore-filling carbonate (calcite?) 

cement was being dissolved. Both processes occur in acidic 

pore waters. Surdam and others (1989) proposed that these 

reactions occur in the "zone of intense diagenesis" and in a 

burial temperature interval from 80 to 120 °C. The reactions 

are thought to be produced by increasing concentrations of 

organic acids that dissolve carbonate minerals and feldspar

H14 Evolution of Sedimentary Basins Anadarko Basin
30 26 18 14 

DEGREES 26

Figure 12. Typical X-ray powder diffraction profiles of 

oriented, <2-[im fraction of rocks of the Siinpson Croup from 

Mazur well showing discrete illite, chlorite, and apparent 

mixed-layer illite/smectite (I/S) basal (001) reflections. Apparent 

I/S defined by diagonal pattern. Cu Ka radiation.

and precipitate kaolinite, chlorite, and other phases. Kaolinite in the Simpson samples probably was later replaced, 

or was converted to, iron-rich chlorite during maximum 

burial.

Using the models of Schmoker (1986) and Pollastro 

and Schmoker (1989), burial- and thermal-history reconstructions were made for the Mazur well. Burial-history 

reconstructions for the Anadarko basin suggest a minimum 

erosion estimate of about 2,600 ft (Schmoker, 1986). 

Assuming a constant geothermal gradient of 1.3 °F/100 ft 

(2.37 °C/100 m) and a mean annual surface temperature 

during maximum burial of 65 °F (17 °C), maximum 

estimated temperatures for the uppermost (15,900 ft, 4,850 

m) and lowermost (17,200 ft, 5,240 m) cored intervals in the 

Mazur well are 150 and 160 °C, respectively.

The clay minerals in the Simpson Group of the Mazur 

well can be used as geothermometers. Applying the model 

of Hoffman and Hower (1979), an assemblage of illite, 

ordered I/S (R>1), and chlorite and a distinct absence or 

disappearance of kaolinite and smectite indicate that burial 

temperatures were at least 150 °C.

Formation of Dolomite and 

Ankerite Cements

Cementation and replacement by dolomite, both 

ferroan and nonferroan, and ankerite was pervasive throughout the entire section of Simpson Group rocks in the Mazur 

core. These authigenic phases are present as isolated rhombs 

to extensive cements in both sandstones and carbonate 

rocks. The evolution of dolomitic cements is similar to the 

evolution of ferroan calcite cements; iron-rich dolomite or

ankerite replaced or succeeded earlier iron-free or iron-poor 

dolomite. This order of genesis is best displayed by stained 

thin sections in which darker stained overgrowths of 

ankerite encase rhombs of earlier, clearer iron-free dolomite 

(fig. 11C).

There is a consistent relation where rhombs of 

dolomite or ankerite are proximally and texturally associated with clay and calcite. The dolomite and ankerite 

commonly replace detrital clay matrix (figs. 10S and \\D}. 

Boles (1978) proposed that the spatial associations between 

carbonate and clay in sandstones of the Wilcox Group 

(Eocene) of southwestern Texas suggest that ankerite 

formation was the direct product of calcite dissolution and 

smectite diagenesis at temperatures in excess of 125 °C. It 

is also suggested here that some late dolomite and ankerite 

cements were formed during the conversion of smectite to 

illite. Several investigators have suggested that the release 

of calcium, magnesium, and iron from the smectite to illite 

reaction produces dolomite and other authigenic mineral 

phases in sedimentary rocks during deep burial diagenesis 

(Boles and Franks, 1979; McHargue and Price, 1982; 

Pollastro, 1985). The consistent spatial and textural 

relations of dolomite, clay, and calcite and the absence of 

smectite, as determined from XRD profiles, support the 

concept that clay-mineral diagenesis played a role in the 

formation of late dolomite and ankerite.

The formation of dolomite and ankerite from clay is 

illustrates m figure 14A based on spatial relationships 

shown in th photomicrograph of figure \4B. Calcium, iron, 

and magn-^ium are released during the conversion of 

smectite to iilite. As smectite is converted to illite, smectite 

is dissolved and illite is precipitated (Nadeau, 1985; Pollastro, 1985). Calcium, magnesium, and iron probably nucleate 

dolomite and ankerite within the clay matrix of sandstones, 

and dolomite and ankerite grow, in part, at the expense of 

the clay. Similar to the interpretation of Boles (1978), much 

of the calcium for dolomite and ankerite formation in 

sandstones of the Simpson Group is probably derived from 

the dissolution of local calcite cement. This reaction 

mechanism is thought to have formed some of the dolomite 

and ankerite; however, it cannot explain the extensive 

cementation by ankerite.

SUMMARY

Rocks of the Simpson Group from the Mazur well 

consist mainly of quartz sandstone, clay-rich shale, and 

mixed carbonate rocks. Although whole-rock mineral 

compositions of the Simpson Group from the Mazur well 

are somewhat variable, clay minerals are mainly illite and 

chlorite. The clay-mineral assemblage in rocks at these 

depths is mostly the result of diagenesis wherein burial 

temperatures exceeded 150 °C. Clay diagenetic reactions 

may also have contributed directly to the formation of late

Middle Ordovician Simpson Group, Oklahoma H15
Figure 13. Scanning electron micrographs of rocks of the Simpson Croup from the Mazur well. Scale bars are 1.0 jam. A, Illitic 

cement with cornflake habit and illite overgrowths (OC) in sandstone. B, Higher magnification of cement in A showing 

intergrowths (I) and overgrowths (OC) of tabular fibers of illite. C, Shale fabric showing platelets (I) and intergrowths (1C) of illite. 

D, Stacked clay plates of pseudomorphic pore-filling chlorite (Ch) after kaolinite. Note striated dissolution features (arrows) 

characteristic of vermicular kaolinite.

dolomite and ankerite cements in sandstone. Most sandstones are quartzarenites that commonly contain appreciable 

cement. Petrologic observations show that original textures 

and whole-rock mineral compositions of sandstones were 

significantly modified by replacement and cementation by 

carbonate minerals. Shales are clay rich and quartz poor; 

either they formed mainly from volcanic debris, or some 

silica was removed during progressive burial; some silica 

expelled from deep burial diagenesis of shales may have 

also been transported updip for early quartz cementation in 

sandstones. Secondary porosity, as much as 11 percent, is 

best developed in sandstones from the Tulip Creek and Oil 

Creek Formations and resulted from the dissolution of 

earlier carbonate cements.

REFERENCES CITED

Alder, J.J., 1971, Anadarko basin and central Oklahoma area, in 

Future petroleum provinces of the U.S.-Their geology and 

potential: American Association of Petroleum Geologists 

Memoir 15, p. 1061-1070.

Boles, J.R., 1978, Active ankerite cementation in the subsurface 

Eocene of southwest Texas: Contributions to Mineralogy 

and Petrology, v. 68, p. 13-22.

Boles, J.R., and Franks, S.G., 1979, Clay diagenesis in Wilcox 

sandstones of southwest Texas Implications of smectite 

diagenesis on sandstone cementation: Journal of Sedimentary Petrology, v. 49, p. 55-70.

Burtner, R.L., and Warner, M.A., 1986, Relationship between 

illite/smectite diagenesis and hydrocarbon generation in 

Lower Cretaceous Mowry and Skull Creek Shales of the

H16 Evolution of Sedimentary Basins Anadarko Basin
D

B r

Figure 14. Formation of authigenic dolomite and ankerite in deeply buried rocks of the Simpson Group from the Mazur well. 

A, Diagrammatic interpretation of textures in thin section photomicrograph in B showing the formation and evolution of dolomite 

and ankerite (D) from clay (IS) and calcite (C) cement. Elements exchanged in the reaction when smectite (Sm) is converted to illite 

(II) include calcium (Ca), magnesium (Mg), and iron (Fe) in deeply buried sandstones and carbonate rocks. Q, quartz. Scale bar 

in B is 0.2 mm.

northern Rocky Mountain area: Clays and Clay Minerals, 

v. 34, p. 390-402.

Carson, B., and Arcaro, N.P., 1983, Control of clay-mineral 

stratigraphy by selective transport in Late PleistoceneHolocene sediments of northern Cascadia basin-Juan de 

Fuca Abyssal Plain Implications for studies of claymineral provenance: Journal of Sedimentary Petrology, 

v. 53, p. 395-406.

Decker, C.E., and Merritt, C.A., 1931, The stratigraphy and 

physical character of the Simpson Group: Oklahoma 

Geological Survey Bulletin 55, 112 p.

Dickson, J.A.D., 1966, Carbonate identification and genesis as 

revealed by staining: Journal of Sedimentary Petrology, 

v. 36, p. 491-505.

Drever, J., 1973, The preparation of oriented clay mineral 

specimens for X-ray diffraction analysis by a filter membrane peel technique: American Mineralogist, v. 58, p. 395- 

406.

Gautier, D.L., ed., 1986, Roles of organic matter in sediment 

diagenesis: Society of Economic Paleontologists and Mineralogists Special Publication 38, 203 p.

Hoffman, J., 1976, Regional metamorphism and K-Ar dating of 

clay minerals in Cretaceous sediments of the disturbed belt 

of Montana: Cleveland, Ohio, Case Western Reserve University, Ph.D. thesis, 266 p.

Hoffman, J., and Hower, J., 1979, Clay mineral assemblages as 

low-grade metamorphic geothermometers Application to 

the thrust faulted disturbed belt of Montana, U.S.A., //j 

Scholle, P.A., and Schluger, P.K., eds., Aspects of diagenesis: Society of Economic Paleontologists and Mineralogists Special Publication 26, p. 55-79.

Hosterman, J.W., and Whirlkow, S.I., 1983, Clay mineralogy of 

Devonian shales in the Appalachian basin: U.S. Geological 

Survey Professional Paper 1298, 31 p.

Houseknecht, D.W., 1988, Intergranular pressure solution in four 

quart/ose sandstones: Journal of Sedimentary Petrology, 

v. 58, p. 228-246.

Hower, J., 1981, Shale diagenesis, i/z Longstaffe, F.J., ed., Clays 

and the resource geologist: Mineralogical Association of 

Canada Short Course Handbook 7, v. 6, p. 60-80.

Hower, J., Eslinger, E., Hower, M., and Perry, E., 1976, The 

mechanism of burial diagenetic reactions in argillaceous 

sediments; 1, Mineralogical and chemical evidence: Geological Society of America Bulletin, v. 87, p. 725-737.

Johnson. K.S., Burchfield, M.R., and Harrison, W.E., 1984, 

Guidebook for Arbuckle Mountain field trip, southern 

Oklahoma: Oklahoma Geological Survey Special Publication 84-1, 21 p.

Lewis, R.D, 1982, Depositional environments and paleoecology of 

the Oil Creek Formation (Middle Ordovician), Arbuckle 

Mountains and Criner Hills, Oklahoma: University of Texas 

at Austin, Ph.D. thesis, 351 p.

Lindquist, S.J., 1978, How mineral content affects reservoir 

quality of sands: World Oil, April 1978, p. 99-102.

Longman, M.W., 1976, Depositional history, paleoecology, and 

diagenesis of the Bromide Formation (Ordovician), 

Arbuckle Mountains, Oklahoma: University Texas at 

Austin, Ph.D. thesis, 327 p.

Loucks, R.G., Dodge, M. M., and Galloway, W. E., 1979, Contract 

report EG-77-5-05-5554: University of Texas Bureau of 

Economic Geology, 97 p.

MacGowan, D.B., and Surdam, R.C., 1988, Difunclional organic 

acid anions in oilfield waters: Organic Geochemistry, v. 12, 

p. 245-259.

McBride, E.F., 1987, Diagenesis of the Maxon Sandstone (Early 

Cretaceous), Marathon Region, Texas A diagenetic 

quartzarenite: Journal of Sedimentary Petrology, v. 31, 

p. 98-107.

Middle Ordovician Simpson Group, Oklahoma HI 7
McDonald, D.A., and Surdam, R.C., 1984, Clastic diagenesis:

American Association Petroleum Geologists Memoir 37,

434 p. 

McHargue, T.R., and Price, R.C., 1982, Dolomite from clay in

argillaceous or shale-associated marine carbonates: Journal

of Sedimentary Petrology, v. 51, p. 553-562. 

Nadeau, P.H., 1985, The physical dimensions of fundamental clay

particles: Clay Minerals, v. 20, p. 499-514. 

Nadeau, P.H., Wilson, M.J., McHardy, W.J., and Tail, J.M., 1984a,

Interparticle diffraction A new concept for interstratified

clays: Clay Minerals, v. 19, 757-769. 

____ 1984b, Interstratified XRD characteristics of physical

mixtures of elementary clay particles: Clay Minerals, v. 19,

p. 67-76. 

____ 1985, The nature of some illitic clays from bentonites and

sandstones Implications for the conversion of smectite to 

illite during diagenesis: Mineralogical Magazine, v. 49, 

p. 393^00.

Naeser, N.D., and McColloh, T.H., eds., 1989, Thermal history of 

sedimentary basins: New York, Springer-Verlag, 320 p.

Pettijohn, F.J., 1975, Sedimentary rocks (3rd ed.): New York, 

Harper and Row, 628 p.

Pettijohn, F.J., Potter, P.E., and Siever, R., 1973, Sand and 

sandstone: New York, Springer-Verlag, 618 p.

Pitman J.K., and Burruss, R.C., 1988, Diagenesis of hydrocarbonbearing rocks in the Ordovician Simpson Group, southeast 

Anadarko basin, in Johnson, K.E., ed., Anadarko Basin 

Symposium, 1988: Oklahoma Geological Survey Circular 

90, p. 134-142.

Pollastro, R.M., 1977, A reconnaissance analysis of the clay 

mineralogy and major element geochemistry in the Silurian 

and Devonian carbonates of western New York A vertical 

profile: State University of New York at Buffalo, M.A. 

thesis, 119 p.

____ 1981, Authigenic kaolinite and associated pyrite in chalk 

of the Cretaceous Niobrara Formation, eastern Colorado: 

Journal of Sedimentary Petrology, v. 51, p. 553-562.

____ 1982, A recommended procedure for the preparation of 

oriented clay-mineral specimens for X-ray diffraction analysis Modifications to Drever's filter-membrane-peel technique: U.S. Geological Survey Open-File Report 82-71, 

10 p.

____ 1983, The formation of illite at the expense of illite/ 

smectite: Mineralogical and morphological support for a 

hypothesis [abs.]: Clay Minerals Society, 20th Annual 

Meeting, 32nd Annual Clay Minerals Conference, Buffalo, 

N.Y., Program and Abstracts, p. 82.

____ 1985, Mineralogical and morphological evidence for the 

formation of illite at the expense of illite/smectite: Clays 

and Clay Minerals, v. 33, p. 265-274.

____ 1989a, Mineralogic and textural relations in deeply buried 

rocks of the Simpson Group (Middle Ordovician) Implications in diagenesis and petroleum geology, in Johnson, 

K.S., ed., Anadarko Basin Symposium, 1988: Oklahoma 

Geological Survey Circular 90, p. 194-208.

____ 1989b, Mineral composition, petrography, and diagenetic 

modification of lower Tertiary and Upper Cretaceous 

sandstones and shales, northern Green River basin, Wyoming, in Law, B.E., and Spencer, C.W., eds., Geology of light

gas reservoirs in the Pinedale anticline area, Wyoming, and 

at the Multiwell Experiment site, Colorado: U.S. Geological 

Survey Bulletin 1886, p. D1-D40.

Pollastro, R.M., and Barker, C.E., 1986, Application of claymineral, vitrinite reflectance, and fluid inclusion studies to 

the thermal and burial history of the Pindale anticline, Green 

River basin, Wyoming, in Gautier, D.L., ed., Roles of 

organic matter in sediment diagenesis: Society of Economic 

Paleontologists and Mineralogists Special Publication 38, 

p. 73-83.

Pollastro, R.M., and Martinez, C.J., 1985, Whole-rock, insoluble 

residue, and clay mineralogies of marl, chalk, and bentonite, 

Smoky Hill Shale Member, Niobrara Formation near 

Pueblo, Colorado Depositional and diagenetic implications, in Pratt, L.M., Kauffman, E.G., and Zelt, F.B., eds.. 

Fine-grained deposits and biofacies of the Cretaceous 

Western Interior seaway Evidence of cyclic sedimentary 

processes: Society of Economic Paleontologists and 

Mineralogists Field Trip Guidebook, p. 215-222.

Pollastro, R.M., and Pillmore, C.L, 1987, Mineralogy and 

petrology of the Cretaceous-Tertiary boundary clay bed and 

adjacent clay-rich rocks, Raton basin. New Mexico and 

Colorado: Journal of Sedimentary Petrology, v. 57, p. 456- 

466.

Pollastro, R.M., and Schmoker, J.W., 1989, Relationship of 

clay diagenesis to temperature, age, and hydrocarbon 

generation An example from the Anadarko basin, Oklahoma, in Johnson, K.S., ed.. Anadarko Basin Symposium, 

1988: Oklahoma Geological Survey Circular 90, p. 257- 

261.

Pollastro, R.M., and Scholle, P.A., 1986, Diagenetic relationships 

in a hydrocarbon-productive chalk The Cretaceous Niobrara Formation, in Mumpton, F.A., ed., Studies in diagenesis: U.S. Geological Survey Bulletin 1578, p. 219-236.

Rascoe, B., Jr., and Adler, F.J., 1983, Permo-Carboniferous 

hydrocarbon accumulations, Mid-Continent, U.S.A.: American Association of Petroleum Geologists Bulletin, v. 67, 

p. 979-1001.

Reynolds, R.C., Jr., 1980, Interstratified clay minerals, in Brindley, 

G.W., and Brown, G., eds., Crystal structure of clay 

minerals and their X-ray identification: Mineralogical 

Society, London, p. 247-303.

Reynolds, R.C., Jr., and Hower, J., 1970, The nature of interlayering in mixed-layer illile-montmorillonite: Clays and Clay 

Minerals, v. 18. p. 25-36.

Samson, S.D., Patchett, P.J., Roddick, J.C., and Parrish, R.R., 

1989, Origin and tectonic setting of Ordovician bentonites 

in North America Isotopic and age constraints: Geological 

Society of America Bulletin, v. 101, p. 1175-1181.

Schmoker, J.W., 1986, Oil generation in the Anadarko basin, 

Oklahoma and Texas Modeling using Lopatin's method: 

Oklahoma Geological Survey Special Publication 86-3, 

40 p.

Scholle, P.A., and Schluger, P.R., eds., 1979, Aspects of diagenesis: Society of Economic Paleontologisls and Mineralogists Special Publication 26, 443 p.

Schoonmaker, J., Mackenzie, F.T., and Speed, R.C., 1986, 

Tectonic implications of illite/smectite diagenesis, Barbados accretionary prism: Clays and Clay Minerals, v. 34, 

p. 465^72.

HIS Evolution of Sedimentary Basins Anadarko Basin
Schramm, M.W., Jr., 1964, Paleogeologic and quantitative lithofacies analysis, Simpson Group, Oklahoma: American 

Association of Petroleum Geologists Bulletin, v. 48, 

p. 1164-1195.

Schultz, L.G., 1964, Quantitative interpretation of mineralogical 

composition from X-ray and chemical data for the Pierre 

Shale: U.S. Geological Survey Professional Paper 391-C, 

31 p.

____ 1978, Sample packer for randomly oriented powders in 

X-ray diffraction analysis: Journal of Sedimentary 

Petrology, v. 48, p. 627-629.

Schultz, L.G., Tourtelot, H.A., Gill, J.R., and Boerngen, J.G., 

1980, Composition and properties of the Pierre Shale and 

equivalent rocks, Northern Great Plains Region: U.S. 

Geological Survey Professional Paper 1064 B, 114 p.

Scotchman, I.C., 1987, Clay diagenesis in the Kimmeridge Clay 

Formation, onshore UK. and its relation to organic 

maturation: Mineralogical Magazine, v. 51, p. 535-551.

Surdam, R.C., Crossey, L.J., Hagen, E.S., and Heasler, H.P., 1989, 

Organic-inorganic interactions and sandstone diagenesis: 

American Association of Petroleum Geologists Bulletin, 

v. 73, p. 1-23.

Taylor, J.M., 1950, Pore-space reduction in sandstones: American 

Association of Petroleum Geologists Bulletin, v. 34, 

p. 701-716.

Weaver, C.E., 1979, Geothermal alteration of clay minerals and 

shales: Office of Nuclear Waste Isolation Technical Report 

21, 176 p.

____ 1989, Clays, muds, and shales, Developments in sedimentology 44: New York, Elsevier, 820 p.

Weber, S.J., 1987, Petrography and diagenesis of the McLish 

Formation, Simpson Group (Middle Ordovician), southeastern Anadarko basin, Oklahoma: Norman, Oklahoma 

State University, M.S. thesis, 98 p.

* U.S. GOVERNMENT PRINTING OFFICE 1991 576-957 Middle Ordovician Simpson Group, Oklahoma H19

SELECTED SERIES OF U.S. GEOLOGICAL SURVEY PUBLICATIONS

Periodicals

Earthquakes & Volcanoes (issued bimonthly). 

Preliminary Determination of Epicenters (issued monthly).

Technical Books and Reports

Professional Papers are mainly comprehensive scientific reports of 

wide and lasting interest and importance to professional scientists and engineers. Included are reports on the results of resource studies and of 

topographic, hydrologic, and geologic investigations. They also include 

collections of related papers addressing different aspects of a single scientific topic.

Bulletins contain significant data and interpretations that are of lasting scientific interest but are generally more limited in scope or 

geographic coverage than Professional Papers. They include the results 

of resource studies and of geologic and topographic investigations; as well 

as collections of short papers related to a specific topic.

Water-Supply Papers are comprehensive reports that present significant interpretive results of hydrologic investigations of wide interest 

to professional geologists, hydrologists, and engineers. The series covers 

investigations in all phases of hydrology, including hydrogeology, 

availability of water, quality of water, and use of water.

Circulars present administrative information or important scientific 

information of wide popular interest in a format designed for distribution 

at no cost to the public. Information is usually of short-term interest.

Water-Resources Investigations Reports are papers of an interpretive nature made available to the public outside the formal USGS publications series. Copies are reproduced on request unlike formal USGS 

publications, and they are also available for public inspection at 

depositories indicated in USGS catalogs.

Open-File Reports include unpublished manuscript reports, maps, 

and other material that are made available for public consultation at 

depositories. They are a nonpermanent form of publication that may be 

cited in other publications as sources of information.

Maps

Geologic Quadrangle Maps are multicolor geologic maps on 

topographic bases in 71/2- or 15-minute quadrangle formats (scales mainly 1:24,000 or 1:62,500) showing bedrock, surficial, or engineering geology. Maps generally include brief texts; some maps include structure 

and columnar sections only.

Geophysical Investigations Maps are on topographic or planimetric 

bases at various scales; they show results of surveys using geophysical 

techniques, such as gravity, magnetic, seismic, or radioactivity, which 

reflect subsurface structures that are of economic or geologic significance. 

Many maps include correlations with the geology.

Miscellaneous Investigations Series Maps are on planimetric or 

topographic bases of regular and irregular areas at various scales; they 

present a wide variety of format and subject matter. The series also includes 71/2-minute quadrangle photogeologic maps on planimetric bases 

which show geology as interpreted from aerial photographs. Series also 

includes maps of Mars and the Moon.

Coal Investigations Maps are geologic maps on topographic or 

planimetric bases at various scales showing bedrock or surficial geology, stratigraphy, and structural relations in certain coal-resource areas.

Oil and Gas Investigations Charts show stratigraphic information 

for certain oil and gas fields and other areas having petroleum potential.

Miscellaneous Field Studies Maps are multicolor or black-andwhite maps on topographic or planimetric bases on quadrangle or irregular areas at various scales. Pre-1971 maps show bedrock geology 

in relation to specific mining or mineral-deposit problems; post-1971 

maps are primarily black-and-white maps on various subjects such as 

environmental studies or wilderness mineral investigations.

Hydrologic Investigations Atlases are multicolored or black-andwhite maps on topographic or planimetric bases presenting a wide range 

of geohydro logic data of both regular and irregular areas; principal scale 

is 1:24,000 and regional studies are at 1:250,000 scale or smaller.

Catalogs

Permanent catalogs, as well as some others, giving comprehensive listings of U.S. Geological Survey publications are available under 

the conditions indicated below from the U.S. Geological Survey, Books 

and Open-File Reports Section, Federal Center, Box 25425, Denver, 

CO 80225. (See latest Price and Availability List)

"Publications of the Geological Survey, 1879-1961" may be purchased by mail and over the counter in paperback book form and as a 

set of microfiche.

"Publications of the Geological Survey, 1962-1970" may be purchased by mail and over the counter in paperback book form and as a 

set of microfiche.

"Publications of the U.S. Geological Survey, 1971-1981" may be 

purchased by mail and over the counter in paperback book form (two 

volumes, publications listing and index) and as a set of microfiche.

Supplements for 1982,1983,1984,1985,1986, and for subsequent 

years since the last permanent catalog may be purchased by mail and 

over the counter in paperback book form.

State catalogs, "List of U.S. Geological Survey Geologic and 

Water-Supply Reports and Maps For (State)," may be purchased by mail 

and over the counter in paperback booklet form only

"Price and Availability List of U.S. Geological Survey Publications," issued annually, is available free of charge in paperback booklet form only.

Selected copies of a monthly catalog "New Publications of the U.S. 

Geological Survey" available free of charge by mail or may be obtained 

over the counter in paperback booklet form only. Those wishing a free 

subscription to the monthly catalog "New Publications of the U.S. 

Geological Survey" should write to the U.S. Geological Survey, 582 

National Center, Reston, VA 22092.

Note.-Prices of Government publications listed in older catalogs, 

announcements, and publications may be incorrect. Therefore, the 

prices charged may differ from the prices in catalogs, announcements, 

and publications.