Stratigraphical Analysis of Triassic and Lower Jurassic Rocks in Northeastern Arizona

Home , Chimney Rock (Utah), Kayenta Formation, Moenave Formation, Moenkopi Formation, Owl Rock

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Link to Item http://hdl.handle.net/10150/231216 STRATIGRAPHICAL ANALYSIS OF TRIASSIC AND LOWER

JURASSIC ROCKS IN NORTHEASTERN ARIZONA

Ali -Reza Ashouri

cT -. Q h r1'., >' I '-OOits ry..,J VCr,.f"h-: iCE$ UN1vER 1-0,ILU1_liA

A Thesis Submitted to the Faculty of the

DEPARTMENT OF GEOSCIENCE

In Partial Fulfillment of the Requirements For the Degree of

MASTER OF SCIENCE

In the Graduate College

THE UNIVERSITY OF ARIZONA

1 9 8 0 STATEMENT BY AUTHOR

This thesis has been submitted in partial fulfillment of requirements for an advanced degree at The University of Arizona and is deposited in the University Library to be made available to borrowers under rules of the Library.

Brief quotations from this thesis are allowable without special permission, provided that accurate acknowledgment of source is made. Requests for permission for extended quotation from or reproduction of this manuscript in whole or in part may be granted by the head of the major department or the Dean of the Graduate College when in his judg- ment the proposed use of the material is in the interests of scholarship. In all other instances, however, permission must be obtained from the author.

SIGNED: A4c-4")

APPROVAL BY THESIS DIRECTOR

This thesis has been approved on the date shown below:

RICHARD F. WILSON bate Professor of Geoscience ACKNOWLEDGMENTS

I wish to express my heart -felt thanks to the members ofmy

committee; to Dr. H. W. Peirce who providedme with useful comments

and discussion during the preparation of this thesis, andto Dr. T. L.

Smiley who also aided my thesis development, and helped directme

through my course of study.

I cannot adequately write or say my gratitude tomy advisor

Dr. R. F. Wilson for all the help and guidance he has offeredme dur-

ing my academic studies and development of this thesisto its conclu-

sion. His scholarship and personal understanding imparted tome the

skills of a geologist, and the human appreciation of theprocess of

mentor ship.

I also wish to thank Dr. M. Shafiqullah for his very useful

discussion. Finally, an appreciated thanks to my friend Jeff Zauderer

for his various comments.

111 TABLE OF CONTENTS

Page

LIST OF ILLUSTRATIONS . . . . . vi

ABSTRACT . . viii

CHAPTER

1 INTRODUCTION . 1

General Statement . 1

Location of Study Area . 1

Methods of Study . . . . . 5

2 REVIEW OF THE STUDIED FORMATION . . 11

Moenkopi Formation . 11

Chinle Formation . . 12 Church Rock Member of Chinle Formation and Rock

Point Member of Wingate Sandstone . 14

Glen Canyon Group . . . 14

General Statement . 14

Wingate Sandstone ...... 15

Moenave Formation . 16 Kayenta Formation 17

Navajo Sandstone . . . 18

3 MAP INTERPRETATION . . . . 20

General Statement . . . . . 20

Moenkopi Formation Interval . 20

Chinle Formation Interval . . . . 25

Glen Canyon Group Interval ...... 33

General Statement . . 33 Isopach Map of Total Glen Canyon Group

Interval . . . . . 33

Wingate Sandstone . 36

Moenave Formation . 42 Kayenta Formation 48

Navajo Sandstone . 5 3

4 CONCLUSION . . 58

iv V

TABLE OF CONTENTS (Continued)

Page

APPENDIX A: INDEX TO LOCATION OF CONTROL POINTS AND SOURCE

OF DATA . 61

LIST OF REFERENCES . . 71 LIST OF ILLUSTRATIONS

Figure Page

3 1. Index Map of Study Area . .

2. Sketch Showing Well Numbering System Used in theStudy Area 6

3. Chart Showing Triassic and Early JurassicFormations and Lesser Subdivision in the Northeastern Arizona . 7

. . . 21 4. Index Map of Moenkopi Formation . . . .

. . 22 5. Isopach Map of Moenkopi Formation . .

6. Shale /Sand Ratio Map of Moenkopi Formation 24

7. Cross Sections of Moenkopi Formation in pocket

8. Index Map of Chinle Formation . 28

. . . 29 9. Isopach Map of Chinle Formation . .

. . . . 31 10. Triangle Facies Map of Chinle Formation .

11. Cross Sections of Chinle Formation in pocket

12. Cross Sections of Glen Canyon Group . . . . in pocket

13. Index Map of Glen Canyon Group . . . 34

14. Isopach Map of Glen Canyon Group . . 35

. . . . 37 15. Index Map of Wingate Sandstone .

16. Isopach Map of Wingate Sandstone 38

17. Sand /Shale Ratio Map of Wingate Sandstone 41

18. Index Map of Moenave Formation 44

19. Isopach Map of Moenave Formation . . . 45

20. Sand /Shale Ratio Map of Moenave Formation 47

vi vii

LIST OF ILLUSTRATIONS (Continued)

Figure Page

21. Index Map of Kayenta Formation ...... 49

22. Isopach Map of Kayenta Formation ...... 50

23. Sand /Shale Ratio Map of Kayenta Formation 52

24. Index Map of Navajo Sandstone ...... 54

25. Isopach Map of Navajo Sandstone ...... 55

26. Sand /Shale Ratio Map of Navajo Sandstone . . 57 ABSTRACT

A review of all available surface and subsurface data on

Triassic and Lower Jurassic rocks in northeastern Arizona has revealed the following information. The Moenkopi Formation, the Chinle Formation, and the Glen Canyon Group of Traissic and Early Jurassic age are present throughout most of the study area. These units form a sequence of continental and transitional marine origin that shows notable vertical and lateral facies changes.

The Moenkopi Formation thickening west and northwestward with a maximum thickness of 134 meters. The unit comprises sandstone and shale, and shows more shaley facies westward.

The Chinle Formation shows minimum thickness to the north and thickens toward east and south with a maximum thickness toward west.

This unit dominantly consists of sandy shale, but contains more sand-

stone westward and north westward. The unit contains some limestone in north and northern region.

The Chinle Formation is overlain by the Glen Canyon Group, which in ascending order comprises the Wingate Sandstone, the Moenave Formation, the Kayenta Formation, and the Navajo Sandstone. The Wingate Sandstone shows its maximum thickness in the central and southcentral region of the study area and thins west and eastward. This unit mainly comprises sandstone, particularly in its upper part.

viii ix

The Moenave Formation displays its zero thickness,in the eastern region and shows its maximum thickness, 198 meters,in the west - central part. The unit mainly consist of sandstone.

The Kayenta Formation attains its greatest thickness, 204 meters, in the southwestern part of the region and thins east and northward.

This formation contains high percentages of sandstone.

Within the area of this study, the Navajo Sandstone is the thickest formation in the Glen Canyon Group. This unit almost entirely consist of sandstone pinches out toward the south and east, and displays its maximum thickness,300 meters, northward. CHAPTER 1

INTRODUCTION

General Statement

The Moenkopi and Chinle Formations of Traissic Age and the

Glen Canyon Group of Late Triassic and Early Jurassic Age are present in most of northeastern Arizona, either in the surface or subsurface.

Both surface and subsurface data were used in this study for a review and analysis of Triassic and lower Jurassic rocks. The study area mainly is the Black Mesa basin and adjacent areas in northeastern Ar- izona. For more detail, the whole stratigraphic section studied is divided into three sequences, in ascending order:Moenkopi Formation,

Chinle Formation, and the Glen Canyon Group.

Location of Study Area

The study area mainly comprises Black Mesa and adjacent areas in northeastern Arizona. This area is approximately 85,000 kilometers square, and limited by 35° to 37° 15'latitude, and 108° 30 to 112° longitude.

The area is a part of the Colorado Plateau. The Colorado Pla- teau is an elevated structural platform of flat-lying sedimentary strata comprising an area of 338,000 square kiometers in Utah, Colorado,

Arizona, and New Mexico. The structure within the Colorado Plateau is

1 2 relatively simple. Monoclines, faulted monoclines ,and normal faults

fold and break the strata along generallynorth or northwest - trending belts. Broad uplifts, including the Zuni,Defiance, Monument, Circle

Cliffs, and Uncompahgre uplifts and the SanRafael Swell, elevate the

strata; even larger basins,including the San Juan, Black Mesa,Uinta,

and Piceance basins, depress the strata(Stewart, Poole and Wilson

1972a) .

For the most part, the sedimentary stratathat mantle the Col-

orado Plateau are relatively thinformations of wide extent. The pla-

teau throughout much of Paleozoicand Early Mesozoic time was a broad

shelf area (craton) lying to the eastof the great Cordilleran geocline

of western Utah, Nevada and California. Many of the formations thicken

in the western part of the plateau into ortoward this geocline. Al-

though locally thickened masses of strata weredeposited in deep basins,

no persistent geosynclinesexisted on the plateau (Stewart et al.1972a).

The index map (Fig. 1) is derivedfrom Geohydrologic Data

(Part III 1964). Most data, either logs or stratigraphicsections,

have been taken from thisreference. In this book, all logs and stra-

tigraphic sections are arranged inthe numerical order of the 18 admin-

istrative districts of the Bureauof Indian Affairs and in accordance

with 15- minute quadrangles withineach district. No data are included

in this report from districts13 and 15, which are outside the study

area.

The quadrangle location number indicates theposition of a well

or stratigraphic section within a15- minute quandrangle and consists of 111 110' 109' nrMltnqs 3r Waler WM tlrr f MON 111UyA .Ary JUAN CO CO NAVAJO r ..urw,e arwrnQtpn --- f 3.' ----litt - - 1- --T îi I INvein DIAN REST RVAl1ON vein .....4Y Croon Rent 15 °i OP < o/ 7 WhorlWelts iP - - Thoreau _ f,nn)e1a11 0ece' wall utn Arxrndrvy EXPLANATION Iwneoubrxrndorr of Indian owl Afloirs number d's/rrCl of d'slr'N ,-- 3 ' fh.th, nffli A Irulam Ser1nC! muds Au 1rrnrnul Number nl 15. mewls a>Iedrvgle I Nschool 07 Figure 1. Index Map of Study Area. -- A. Showing roads villages, Bureau of Indian Affairs, 'rlI O 'O -I 10 MM footling pose TP GeohydrologicAdministrative Data, District Part andIII, 15 minute quadrangles 1964) .. (from Arizona State Land Department W r.m..mb 4.4...4.4 ono ! =r = . 4r ì . VÉRMIIOMcuFfs _ :rN:- IM,rO : MONUMENT _ _ ARUoNA I NEw MEXICO UTAN COLORADO . v Vît2:/ o 5, s I TIiM Cltp el AcKMESA b r, 1 fleplolt r- r Gt1T TES M 0' o i -,/,,,, illSokol John* I II*l ,''oI/N I10 1 ,// II Figure 1. Continued. -- B. Showing Natural Features of Study Area (from Wilson 1974) . 5 three parts. The first part is the number of quadrangle in which the well or section is located. The second part is the distance in miles west of the northeast corner of the quadrangle, and the third part is the distance in miles south of the northeast corner of the quadrangle

(Fig. 2). The letter "A" at the end of the quadrangle number means ar, approximate location (Arizona State Land Department 1964).

Methods of Study

This report is prepared on the basis of the data from both surface sections and drill holes that exist in the area. Of major inter- est were those sections that cover the total stratigraphic sequence.

Only a few sections cover almost all of the units. Then incomplete data were gathered from most parts of one of these units (Moenkopi

Formation, Chinle Formation, and Glen Canyon Group), Fig. 3, that included thickness of each formation, thickness of each rock type in each formation, and the percentages of each rock type in each formation.

By using these data, for each of the three above mentioned sequences (including all formations in the Glen Canyon Group), isopach maps and lithofacies maps have been prepared for all formations in the

Glen Canyon. Moreover, the data have been used to preparing some detailed cross sections.

Four detailed cross sections for each interval have been prepared; two of them have west -east directions, one from the north part of the map and the other one from south part. The other two are prepared in a trend of southeast -northwest, one for the east part of the area and the other for the west part of the area. 6

I s

DISTRICT 2

. i L1 I I 1 1 . .! ` ....0"....-. J e i-1fl . I t, ,.. - 1t %'/1 `^\` d I 1 '..% J f1 1.1.'130 W ...., Ii i I. 29 IT-22V. 27 (010041 Inglelocationnun+0e,Z1-330-+6-e01

DISTRICT I

Figure 2. Sketch Showing Well Numbering System Used in the Study Area. -- (From Arizona State Land Department,Geohydrolog. Data, Part III, 1964). 7

Middle and Late Jurassic Carmel Formation

Navajo Sandstone

Kayenta Formation

Springdale Sandstone Moenave Formation Dinosaur Canyon Member

, U Lukachukai Member

( w c v o o

Church Triassic o ro rte+ Rock Rock Point 3m w Member Member

o o Owl Ro..k Member c r, U c H E o -o Upper Part r v W rl H 4 Sonsela Sandstone Bed o r+ en W W rl 4 Q) an E á 6 á w w Lower Part

Monitor Butte Member

Shinarump Member

Middle Triassic

Middle ( ?) and Early Triassic Moenkopi Formation

Early Permian Kaibab Formation Cutler Formation Dechelly Sandstone

Figure 3. Chart Showing Triassic and Early JurassicFormations and Lesser Subdivision in the NortheasternArizona. 8

Control points that have been used for the detailed cross sections were selected from a boundary zone instead of a line because insufficient control points appear along a straight line.

For each interval of isopach and lithofacies maps, a base map is enclosed that includes the location of the control points. In this map the index number used in this paper appears above each control point. The thickness and the lithofacies data appear below and on the right side of each control point respectively. Index number of each control points whose thickness and obviously their facies ratio are incomplete indicated by a plus( +) mark on maps. For more convenience and quick reference, control points and index numbers have been shown on all maps. The index number appears on detailed cross sections also.

The total number of control points used in this report are 98 surface sections (ranges from 1 to 98) and 47 subsurface drill holes that start from 200 (ranges from 200 to 247).

Boundaries between the intervals are different for the maps and for the detailed cross sections. For the Glen Canyon Group interval, the lower boundary is the top of the Owl Rock Member of the Chinle

Formation; on the other hand, for the Chinle Formation interval, the upper boundary is the base of the Lukachukai Member of the Wingate Sand- stone. The boundary between the Chinle Formation interval and the

Moenkopi Formation interval is the base of the Shinarump Member of the

Chinle Formation. The boundary mentioned above have been used for the detailed cross sections, but for the maps, the boundary between the

Glen Canyon Group interval and the Chinle Formation interval is the 9 base of the Rock Point member of the Wingate Sandstone or the top of the Owl Rock Member or Church Rock Member if present.

All references used for gathering the data the thicknesses were given in feet, but in this report all of them have been converted to meters.

Essentially, the formations and top member were accepted almost as given in the references because excepting the Owl Rock Member, which contains some limestones, the total studied stratigraphic section consists of sandstone and shale. Especially for subsurface sections, de- tails are not discussed. Secondly, almost all formations were deposited in local environments where rapid facies changes are common; in other words, because the formation did not form in a widespread environment, so, without examining the formation in the field there is not sufficient evidence to check the boundaries. Commonly two formations not only consist of shale and sandstone, but only consist of one rock type, such as sandstone for both Navajo and Kayenta Formations.

The facies map for Chinle Formation was prepared by using the triangle facies method; whereas for all other units, sand -shale ratios were used. The percentage of conglomerate is low, and appears only locally, thus it has been added to the sandstone percentage. The data sheets used for compiling the information for both subsurface and surface sections are attached as an Appendix A. They are arranged numer- ically by the index number. A separate sheet was used for each interval found at a control point. 10

For convenience, the data by index number below 200 belong to surface sections; but subsurface control starts from number 200.

Before starting the map discussion, let us consider some of the characteristics of each of the formations. CHAPTER 2

REVIEW OF THE STUDIED FORMATION

The following s tratigraphi c information is derived largely from

Wilson (1974), O'Sullivan (1977), and Harshbarger, Repenning and Irwin

(1957).

Moenkopi Formation

The Moenkopi Formation comprises the oldest Triassic strata of northeastern Arizona, and is a reddish brown siltstone and sandstone unit. The unit crops out extensively in the study area, especially around the Little Colorado River Valley and around Cameron along the

Echo and Vermilion Cliffs. Outcrops also are present along the Mogollon

Rim and in the Monument Valley (Wilson 1974).

Throughout northeastern Arizona, the Moenkopi Formation rests unconformably on Permian rocks such as the Kaibab Formation in the western and southwestern part of the region, the Coconino Sandstone in the central part, the De Chelly Sandstone in Monument Valley and the southern part of the Defiance uplift, and the San Andres Limestone in the area around St. Johns (Wilson 1974) .

In the Little Colorado River Valley, the Moenkopi Formation consists of three members. In ascending order these are; the Wupatki Mem- ber, composed principally of reddish -brown horizontally stratified and ripple - laminated siltstone; the Moqui Member which is composed

11 12 principally of reddish -brown and grayish siltstone, and minor amount of white gypsum; and the Holbrook Member which is composed principally of reddish -brown horizontally stratified and ripple -laminated siltstone and cross -stratified sandstone. The Holbrook Member probably represents almost all of the Moenkopi Formation in the southeastern part of

the region and southern part of the Defiance uplift (Wilson 1974).

Chinle Formation

The Chinle Formation is present in outcrop and in the subsur-

face throughout the study area. It rests unconformably on the Moenkopi

Formation throughout the area except in the central and northern part

of the Defiance uplift, where the Chinle Formation unconf ormab le over-

lies the Permian De Chelly Sandstone (Wilson 1974).

On a regional basis, the Chinle Formation has been divided into a lower and an upper part (Stewart, Poole and Wilson 1972b) . The lower part comprises: 1) the basal Shinarump Member, a discontinuous unit of very light gray, light tan and brown fine -to course- grained sandstone,

conglomerate, and minor mudstone beds of variable thickness; 2) a medial group of laterally equivalent members of lenticular ledge -forming sandstone and slope- forming claystone and clayey sandstone termed the

Sandstone and Mudstone Member in the Echo Cliffs area, the Monitor

Butte Member (at many localities characterized by numerous interforma-

tional slump, folds, and faults undoubtedly formed before consolidation) in Monument Valley, the Lower Red Member in the Defiance uplift, and

the Mesa Redondo Member in the eastern part of the Little Colorado 13

River Valley; and 3) the Petrified Forest Member that is composed of a thick sequence, about 250 meters, of varigated blue, gray, red -brown and purple fluviatile mudstone, siltstone, and sandstone. Much of the mudstone contains montmorillonite derived from the alteration of volcanic ash. The Petrified Forest Member in many places is divided into an upper and lower part separated by the Sonsela Sandstone Bed.

The Sonsela Sandstone Bed, widespread in the study area, is a light yellowish gray, cross -bedded tufaceous sandstone containing conglomerate lenses (composed of quartz, quartzite, and chert) and interbedded siltstone. The entire unit is considered of fluvial origin, deposited by streams flowing northward and northwestward from a source area, the Mongollon Highland, to the south (Stewart et al. 1972b;

Poole 1961).

The upper part of the Chinle Formation consists of the Owl Rock

Member, a unit of reddish siltstone and minor amounts of interbedded freshwater limestone.The shale is generally silty and calcareous, and forms slopes. The member is absent at St. Johns owing to Pre - Cretacoues erosion, but is present elsewhere in the region.

The Chinle Formation is the most colorful formation in the study area, and is noted for its abundance of fossil wood, which is conspiculously exposed in the Petrified Forest National Park and in the

Painted Desert. 14

Church Rock Member of Chinle Formation and Rock Point Member of Wingate Sandstone

In northeastern Arizona, a sequence of siltstoneand sandstone overlying the Owl Rock Member is assigned to theChurch Rock Member of the Chinle Formation north of Laguna Creek;whereas south of Laguna

Creek the same beds are assigned to the Rock PointMember of the

Wingate Sandstone (O'Sullivan 1977).

The Church Rock and Rock Point Members consistsof reddish - orange and reddish -brown siltstone and veryfine grained sandstone mot - tled light greenish gray that form a series of ledges andslopes. The contact between the Church Rock and Rock Pointand overlying parts of the Glen Canyon Group, the Lukachukai Member of theWingate Sandstone, has various interpretations (O'Sullivan 1977). Extensive intertonguing has-been reported between the Rock Point and LukachukaiMember (Harsh - barger et al. 1957) but such intertonguing was notdetected anywhere between the Wingate Sandstone and the Church RockMember in the Mon- ument Valley area of Arizona(Wi tkind and Thaden 1963) .

Glen Canyon Group

General Statement

In northeastern Arizona, the Glen CanyonGroup overlies the

Triassic Chinle Formation and underlies the Carmel andEntrada Forma-

tions, which are of Middle and Late JurassicAge (Imlay 1952). The

Glen Canyon Group is divided into four units, in ascending order: the

Wingate Sandstone, the Moenave Formation, the Kayenta Formation, and

the Navajo Sandstone. 15

Wingate Sandstone

The Wingate Sandstone, the basal formation of theGlen Canyon

Group, comprises two members. The Rock Point Member (the lower) and the Lukachukai Member (the upper) . The Rock Point Member consists of reddish -brown siltstone with very thick horizontal bedding, andminor

lenses of fluvial sandstone with trough cross -stratificationin out-

crops near the Utah state line. The member conformably overlies the

Owl Rock of the Chinle Formation, although Harshbarger and others

(1957) suggest unconformity between the Wingate Sandstone and underly-

ing strata.

The status of the Rock Point Member is in question. It orig-

inally was considered part of the Chinle Formation, but was placed in

the Wingate Sandstone by Harshbarger and others (1957). Stewart and

other (1972b) stress the equivalency of this unit to the Church Rock

Member of the Chinle Formation in southeastern Utah. O'Sullivan (1970),

however, has questioned the exact equivalency to most of the Church

Rock Member in Utah. Further study is needed to resolve this question.

The Lukachukai Member of the Wingate Sandstone is equivalent

to the entire Wingate Sandstone of Utah andColorado. This cliff-

forming unit of light -brown planar- cross -stratified sandstone inter -

tongues with the Rock Point Member along the eastflank of the Defiance

uplift, but to the west appears to unconformably overlie the Owl Rock

Member of the Chinle Formation in western exposures where the Rock

Point Member is absent. According to Morris W. Green (1974) , strata

which had been correlated with the Lukachukai Member, in the 16

Gallup- Grants area of New Mexico, were assigned as the IyanbitoMember of the Entrada Sandstone. The Lukachukai Member of eolian origin, de-

posited by winds blowing from the northwest (Poole 1962).

Moenave Formation

Overlying the Wingate Sandstone in most of the western part of the study area is a sequence almost entirely composed of siltstone and sandstone recognized as the Moenave Formation. Because of its stratigraphic position, in places where the Wingate Sandstone is absent the unit has commonly been assigned to the Wingate Sandston (Wanek and

Stephens 1953). However, lateral tracing has revealed that the unit overlies the Wingate Sandstone in some areas, and in composition, depositional history and stratigraphic position the upper member of the

Moenave Formation is related more closely to the type Kayenta Formation than it is to the Wingate Sandstone. The unit comprises an upper cliff - forming sandstone and a lower slope -forming silty sandstone.

The Dinosaur Canyon Member, the basal member of the Moenave

Formation, consists of reddish - orange to pale reddish -brown sandstone and siltstone. The member rests conformably on the Lukachukai Member of the Wingate Sandstone and unconformably on beds of the Chinle Forma- tion west of the pinch out of the Lukachukai Member (Wilson 1974). Two facies of the Dinosaur Canyon Member are recognized along its southern exposures: an eastern facies composed of planar- cross -stratified sandstone of probable eolian origin deposited by winds blowing from the northwest, and a western facies of siltstone and trough sandstone de-

posited by streams flowing northwest, as in Chinle time (Johnson 1967). 17

The Springdale Sandstone Member, the upper member of the

Moenave Formation is a ledge- forming pale -red trough- cross -stratified sandstone. Gregory (1950, p. 67) reports that in the type area the

Springdale Sandstone appears from a distance as a single massive bed which retains its form and thickness as far as the eye can reach. Near views show it to be a series of laminated, in places ripple- marked and cross -bedded ledges and lenses, most of them less than 100 feet long and 10 feet thick. He reports that shale lenses and mud pockets are common in this unit. The Springdale Sandstone is of fluvial origin and was deposited by streams flowing toward the southwest (Wilson 1974).

Kayenta Formation

The Kayenta Formation in northeastern Arizona consists of two distinct lithologic assemblages. One consists largely of ledge -forming pale -red trough- cross -stratified sandstone deposited by streams flowing toward the southwest, and crops out in the northeastern part of the area in Monument Valley, the northwestern Defiance uplift, and in the study area, near the Utah State line east of the Echo Cliffs. This assemblage represents the type Kayenta Formation, and it is probably the equivalent of the Springdale Sandstone Member of the Moenave Forma-

tion in the Echo and Vermilion Cliffs (Wilson 1974).

The other assemblage consists of slope -forming units of siltstone and minor trough- cross -stratified sandstone, locally interstrat- ified in its upper part with tongues of planar cross- stratified Navajo

Sandstone. This unit crops out along the Vermilion and Echo Cliffs, 18 and along the northern fringe of the Little Colorado River Valley. It appears to be a lateral equivalent of the Navajo Sandstonefurther to the north and east, and intertongues with the Navajo in that direction

(Wilson 1974).

Thus, the two recognized assemblages of the Kayenta probably are not lateral equivalents, and the application of the name Kayenta to both is questionable (Wilson 1974) .

Witkind andThaden (1963) used irregular bedding as a character of the Kayenta Formation as a guide for mapping in order to differentiate this formation from both the underlying and overlying massive cross bedded sandstones.

Stewart and others (1959) indicate some interformation conglomerate, irregular bedding, channeling, and general coarsences which indicate a stream deposit origin for the Kayenta Formation; they believe conditions of aridity prevailed and shale lenses were probably deposited in pools of quiet water. They also believe likely most of the sediments came from the north and northeast deposit. Conditions of aridity prevailed and the shale lenses were probably deposited in pools of quiet water. Likely most of the sediments came from the north

and northeast (Stewart et al. 1959).

Navajo Sandstone

The uppermost formation of the Glen Canyon Group is the Navajo

Sandstone, a cliff- forming light -brown to orange planar cross -stratified fine-grained sandstone that crops out extensively in the northern part

of northeastern Arizona (Wilson 1974). 19

The crossbedding in the Navajo Sandstone is oneofits most conspicuous features. It is typically large scale and high angle and of the planar type. These bedding features are identical to those in modern dunes of the transverse and barchan types (Harshbarger et al.

1957). So, it is of eolian origin, deposited by wind blowing from the

north and northwest (Poole 1962). It has been suggested by William E.

Freeman and Glenn S. Visher (1975) that the Navajo Sandstone formed in a marine shelf environment but this suggestion was rejected by many workers.

In northeastern Arizona, the Navajo Sandstone intertongues with the underlying fluvial deposits of the Kayenta Formation, and isuncon- formably overlain by the Middle and Upper Jurassic (Imlay 1952) Carmel

Formation and Entrada Formation.

`^.!¡p I V r ¡ i lit e 1' ` y, r .r9(100/Vi DE_ UNIYEKb11Y Lir etnl10111A CHAPTER 3

MAP INTERPRETATION

General Statement

Discussion of maps will start with the Moenkopi interval.

First the isopach map will be covered. Then lithofacies maps will be discussed. This interval will be completed bya detailed cross section. The next inerval will be the Chinle Formation, and it is covered in same manner as the Moenkopi interval. The Glen Canyon Group contains, in ascending order: the Wingate, Moenave, Kayenta, and Navajo

Formations, for each of the above formations discussion will bepre- sented as for the Moenkopi and Chinle Formations.

Moenkopi Formation Interval

Index map of the Moenkopi Formation is shownas Fig. 4. The

Moenkopi Isopach map (Fig. 5) is fairly simple. In general, it represents a gradual west to northwest thickening of the formation from higher lands in the east. Thickness changes occur gradually in the map area, and toward the south thickness change is extremely slow in- dicating a very low depositional gradient. From the south central part of the map around point 217, toward point 234a gradual northwesterly thickening trend exists that eventually becomesa small basin around point 234.

20 :3 L nt N 6eft1 Y.. Arizona Utah 'ColoradoNew Mexico 1 Index number 45U:C:F.M) ef Il Thickness 264 3.1 facies ratio y .a 0 20 (,p 100 kilometers it Á i}el 10441 V1,,tc its 10 a+ r s1 tStn lilaH 146117-1,1.. arm $v t . . Figure 4. Index Map of Moenkopi Formation. ye (.1 lo 11 js Arizona Utah ColoradoNew Mexico Index numberLECEND loo / \ \ - -- i'~- Contourwhere20Isopach meters inferred interval line dashed I Lo 0 0 20 60 . 100 kilometers ll l 11 401,3 " 1 Mlh Figure 5. Isopach Map of Moenkopi Formation. SI 23

A northwest trending ridge or prong derived from the Defiance uplift across point 6 extends westward into the Moenkopi basin.

Referring to the isopach map indicates that the eastern part of the region was positive throughout Early and Middle Triassic time, and also considering that the Moenkopi Formation formed in continental

and marginal marine environments (O'Sullivan 1977), let's review the

ratio map (Fig. 6).

Four unusual features (points 241, 234, 223, and 68) are evident in the Moenkopi ratio map. Point 241 in near southern flank of the Defiance uplift shows an increase of the shale -sand ratio to the northwest and southwest sides of contours, whereas the axis of contours indicate the lower range of shale -sand ratio. It could be re- ferred to a stream system in which the major drainage occupied the axis of the contours, which therefore contains more sand. Meanwhile, the flanks of the feature indicate more shale perhaps caused by slow deposition.

Another interesting feature in this map is point 234, which is located in the center of a small basin of gentle slope, formed in a marginal marine environment. In fact, a review of both the isopach map and the shale -sand ratio map display a dramatic increase in shale -sand ratio in to the south and southwest compared to the west and northwest which show slow changes in shale -sand ratio.

The next unusual feature is situated around point 68, and is not easy to explain. Either it has a different source, or was a small lagoon, or both. 67 io 69 ColoradoArizona NewUtah Mexico 7 LEGEND Index number V A / ZerodashedRatio isopachcontour where inferredline 29 , . 1 . kilometers L] Figure 6. Shale /Sand Ratio Map of foenkopi Formation. 25

The last unusual point is 223 which is a subsurface point.

Considering two close control points to the southwest of point 223 and the feature around point 241, the shale -sand ratio for point 223 is based either on wrong information due to subsurface problems, or it represents a very local shale tense, or both.

In general, the detailed cross sections (Fig. 7, A, B, C, D, in pocket) are conformable with the isopach and shale -sand ratio maps in that the unit thickens and becomes more shaley to the west. Never- theless, some questions arise about column 223 in the southern west - east section (Fig.7, A) and column 234 in the western southeast -

northwest cross -section (Fig.7, D). Both these columns are based on subsurface data and are not as precise as the surface sections. On the other hand, as mentioned before, the Moenkopi Formation was deposited in continental and marginal marine environments, so rapid lateral facies changes are to be expected, and has been stated in point 234 on the shale -sand ratio map represents a small basin. Although the com- bination of the above mentioned factors could apply to column 223, non - accurate information is more probable.

Chinle Formation Interval

According to Wilson (1974), the Chinle Formation, in general, comprises two parts in northeastern Arizona. The lower part consists of the basal Shinarump Member, composed of a discontinuous unit of variable thickness of sandstone to conglomerate; a medial assemblage of laterally equivalent members of sandstone, claystone, and clayey 26 sandstone of variable thickness termed the Sandstone and Muds tone Member in the Echo Cliffs area, the Monitor Butte Member in Monument Valley, the Lower Red Member in the Defiance Uplift, and the Mesa Redondo Mem- ber in the eastern part of the Little Colorado River Valley; and the upper Petrified Forest Member, consisting of a thick sequence of bentonitic claystone, clayey sandstone, and sandstone.

The upper part of the Chinle Formation in the study area, the

Owl Rock Member, consists of siltstone and minor amounts of limestone

(Wilson 1974, O'Sullivan 1977) . However, a sequence of reddish silt - stone and sandstone rests on the Owl Rock Member, and is assigned to the Church Rock Member of the Chinle Formation in parts of northeastern

Arizona (O'Sullivan 1977).

R. A. Cardigan (oral communication 1967, in O'Sullivan 1977) indicates rapid deposition of the Petrified Forest and older members on the basis of poor intersorting and lack of alteration of the contained tuf f aceous material.

Stewart and others (1972), Schultz (1963), and Poole (1961) considered a fluvial origin for the lower Chinle deposited by streams flowing northward and northwestward from a volcanic source area, the

Mogollon Highland, to the south.

According to O'Sullivan (1977), the study area and adjacent regions were occupied by a large irregularly shaped basin that formed at the beginning of Late Triassic Time.

Harshbarger and others (1957) considered that the Church Rock strata, as well as the Rock Point Member of the Wingate Sandstone, to 27 be deposited in the Rock Point basin in a quiet water environment.

Fig. 8 is an index map of the Chinle Form.

The isopach map of the Chinle Formation (Fig. 9) represents the greatest thickness (426 meters) compared to the other two intervals, the Moenkopi Formation interval (134 meters) and the Glen Canyon

Group interval (389 meters). However, considering that the basal contact and also the upper contact of the Chinle Formation show erosional contacts, its real thickness must have been greater than that which now exists.

In general, control Point 64, located in the northern part of the study area, indicates a minimum thickness of 179 meters. From

Point 64 thickness increases toward the east, south, and west. Control

Point 59, situated at central region of the study area, exhibits a maximum thickness of 426 meters.

The map indicates a basin in the central part of the area with an axis of almost east -west trend. The axis lies across points 87 and

7 eastward and between point 59 and point 89, then switches toward the southeast and ultimately across point 221 and point 32 and continues eastward.

A small ridge or prong is evident in the northern part of the map around points 66, 63, and 62 with a northern trend and gentle slope across point 62. In the north to northwest part of the area from point 65 through point 64 also between point 65 and point 22a dramatic change in thickness is evident that may indicate tectonic movement during the time that the Chinle strata were deposited. LEGEND 11164e. ]6ctt N Index number 45 41 2L.c. 216 6c Thickness 264 B facies ratio 9Gy .c tac1.51. 2ds66c 2S Arizona Utah NewColorado Mexico 1114111+ Sc 1S4' 25 j C gat.V/ Sc Solt 6 .a qo2 L.c !IG .c ,;, qá 270 14 234,1+ t.oe 11,4- . c !ii7Iio x1r1 c 1iqq1' lis + A ,a+ rotsa . c bokt c. !: ifei cM4o 9 20 60 100 kilometers ae a ago ire. le*404 K1 Mt Figure 8. Index Map of Chinle Formation. 1"Z A 410 LEGEND i IndexIsopach number line dashed `IM where inferred ColoradoNew Mexico 4 Contour50 meter interval 400 36,6 ut 31 o 20 60 100 kilometers yó Figure 9. Isopach Map of Chinle Formation. zbS 30

An interesting feature is evident around point 25 located almost on the state line between Arizona and Utah in the northeastern region of the map. This area may represent the southwestern edge of a basin. The rapid changes in thickness shows between point 25 and 90 is likely the result of subsidence.

The facies map (Fig. 10) was prepared by using the triangle facies method. The three major groups of rocks that comprise this unit are shale, sandstone, and limestone, but limestone only appears in the

Owl Rock Member. The entire unit, as the map shows, is mainly com- prised of sandy shale.

Point 7 and point 26 are two unusual points that show more sandstone than the surrounded areas. These points do not include a large area, but are local. Referring to the origin of the Chinle, which is mainly fluvial, and to rapid lateral changes in facies, probably those features indicate some lenticular sandstone units or are the result of inaccurate data.

The southeastern part of the area is composed of the highest percentages of shale. This evidence coincides with the isopach map that located together in the deepest region and the gentle gradient.

A possible reason for the increase in clay -size material toward the inferred source area might be the alteration of sand -size tufftragments to bentonitic clays after deposition.

A review of the detailed cross sections of all three intervals

(Figs. 7, 11, and 12, in pocket) indicates two general differences between the Chinle Formation interval (Fig. 11) and the Glen Canyon Group 116 o61 Sh. LEGEND 61 63 BEkD V Index number GS 11. 64 C Triangle Ratio e- 10 ts Arizona New Mexico Uta ColoradoIMINCL. ink 0 at 2 91 i. C Al I. 44 nt -. N.. W 1 V It ..., ,. y 1111 o a 20 60 1 100 kilometers an A ,. Figure 10. Triangle Facies Map of Chinle Formation. i*S . 32 interval (Fig. 12). One, the Chinle Formation represents more complete control points than the Glen Canyon Group (this difference also exists between the Moenkopi Formation and the Glen Canyon Group). Second, surface sections of the Chinle Formation contain more covered units than the other intervals owing to its shaly material, particularly in the Petrified Forest Member.

Although the Chinle Formation interval predominantly is composed of sand and shale, but according to detailed cross section and with more attention in general, it is represent more sandstone west and northwestward.

Limestone appears dominantly in the northern part of the area around points 25 and 22, which was discussed before, and shows conform- ability with isopach map. Thicker limestone deposits, and less effect of erosion in northern part of the study area, are cause for the pres- ence of limestone strata only in that region.

The Shinarump Member is present at most control points and except for Columns 90 and 64 in the eastern southeast -northwest cross section which consists of shale, at remaining chiefly shows a sandy facies.

The Petrified Forest Member, the thickest member of the Chinle

Formation, contains more sandstone toward west and northwest.

The Owl Rock Member more appears in the eastern southeast - northwest and southern west -east sections, but in the other sections is restricted only to a few columns. 33

Glen Canyon Group Interval

General Statement

The Glen Canyon Group interval will be covered by an index map

(Fig. 13), and an isopach map (Fig. 14) for entire unit. All formations in the Glen Canyon Group also will be discussed by index, isopach, and ratio facies maps. For the total unit detailed cross section map also will be involved (Fig. 12).

Isopach Map of Total Glen Canyon Group Interval

The general features of the isopach map are the zero line to the southeast and thickening trend to the northwest. Some of the Glen Can- yon Group rocks were eroded prior to deposition of subsequent Middle

Jurassic or later rocks.

Almost in the central part of the map, one area of unusual thinning is evident around point 57. Therefore, considering the four forma-

tions of the Glen Canyon Group, the point becomes clear that, either no deposition occurred in this area during Moenave, Kayenta, and Navajo

time, or later erosion occurred, or the data base is incorrect.

In the southwestern part of the map, around point 20, an unusual

thickening exists. From this point toward the east, the thickness changes rapidly. Assuming that most of the deposition in this area be- longs to the Rock Point Member of the Wingate Sandstone which may have formed in a tidal flat or lagoonal environment, this thickening could be

the result of subsidence. :33+Le ` l f±izona New Mexico Utah Colorado 3A1 L." Iÿ14; t Ai rii Zdçt ID'S2` 1 y i)s 11 11 4- l i 23/+ no Li1 i,+ 13 14 ito lie 30 . s»r; 6 + vs '; jq+ r t 3rill LEGEND c 27H l,ei L, i+ f) i n 21 Ay1 I.11 sy 45 Index number f W + Is' 111,' .o IIl 4 14 :r1 i,4A 1 s613 WI 41 ¡1 ji 31 264 Thickness los e,. °. 1 IL7 hS se* =K s19 ;t ;4* ti Figure 13. Index Neap of Glen Canyon Group. 0 20 60 100 kilometers sao is LEGEND -il Index number V Arizona Utah Isopach line dashed 1 1j 211 11 t+8 t;ß v . Contourwhere50 meter inferred interval 22 / / / 30 3.3 t1 11 b to i / ei __ -SS -- it M S 41 Figure 14. Isopach Map of Glen Canyon Group. 0 20 . 60 100 kilometers 36

As was mentioned before, the total trend of thickness is east and southeast to west and northwest, which conforms to the detailed cross sections. As the detailed cross section (Fig. 12) display, in the northern west -east cross section (Fig. 12, C) the thickness in the west is more than five times than in the east. This relation is almost true for

the southern west -east section (Fig. 12, A), thickness in the west is much higher than in the east. Consequently, one can be certain that in the east and southeastern part of the study area was a positive region; and the paleoslope was inclined toward the west.

Wingate Sandstone

The Wingate Sandstone comprises two members in northeastern

Arizona, the Rock Point Member (lower) and the Lukachukai Member (upper) .

The origin of the Rock Member deposits has been variously explained.

According to Harshbarger and others (1957), the Rock Point Member were deposited in a subaqueous lagoonal environment. Stewart and others (1972b) consider it the result of alternating cycles of shallow lacustrine and eolian deposition. Green and Pierson (1977) believe that the high -angle cross -bedded sandstone in the Lukachukai Member is of eolian origin.

Poole (1962) decided that it was deposited by wind blowing from the northwest.

Fig. 15 is the index map for the Wingate Sandstone. The isopach map of the Wingate Sandstone (Fig. 16) is more conspicuous than the other formations in the Glen Canyon Group. The westernmost limit of the study area represents a zero line feature. It thickens to 241 meters in the central part of the area. LEGEND 231165' 0 m 1K66 Arizona Utah NewColorado Mexico 41 t 4 4 l4+ 1'21 96 I l ) 2sl Ás ,61 2 Index number 45 3.1 facies ratio 25 . PS;yl X15 ,s : c ije1 12.1 t 5.: 0 16 ¡ 1}i 24nt 31'1 Thickness 264 il" w1 t Le1 ¡Ì 9 S¡1 e2156 S> 1441p.1 41 mie 246ILI 141 152N 1 21111Sl1515 151 eel 1i1 *131 "-1 p 21 51 et A O 1 2t,16 2t" IlV, s 11-iy4 Ib; v 1` 4 1131: 4 6 0 20 60 el 1as 100 kilometers j..s Figure 15. Index Map of Wingate Sandstone. N IsopachIndex number line dashed Arizona Utah NewColorado Mexico i' i whereContour50 inferredmeter interval 0 1 j, i / es 63 I o / / 150 ut 54 loo 50 t 0 1 e= 100 kilometers : bo if Figure 16. Isopach20 Map of Wingate 60 Sandstone. 39

The Wingate Sandstone attains its greatest thickness withinthe study area in the southcentral part around point 20, where it is283 meters thick. From the central part of the area, the unit thins eastward almost regularly except for an unusual feature around point57, to a zero line at the east edge of the map.

Some unusual features are evident around points 20, 57,both 247 and 55, and 3. Point 20 indicates a basin in the south central partof the area whose flanks, as far as the map indicates, show a normalslope.

Point 57, situated almost in the central part of the region, with only 12 meters thickness, indicates a local positive area in Win- gate time or post Wingate erosion.

Another interesting feature is represented around points 55and

247 shows another basin in the area. This basin indicates a high gradient toward point 57, which is presumably evidence for acontinuing de- pression or post Wingate erosion. The basin displays a steep gradient

from point 55 and northwestward only between contour250 and 200.

Point 3 is the last point which will be discussed. This point

indicates a rapid thickening toward the north to point 233. From point

3 a ridge also is evident toward the northeast point66.

Note that the easternmost limits of the three other formations

(Moenave Formation, Kayenta Formation, and Navajo Sanstone) in the Glen

Canlyon Group are almost along a line that extends from point20 toward

the center point of the Four Corners of Arizona, Utah, Colorado, andNew

Mexico. The Wingate Sandstone is the only formation that is not re-

stricted to this boundary, but continues toward the east. The next

difference between the Wingate Sandstone and the three other formations 40 of the Glen Canyon Group is the western boundary, where the Wingate

Sandstone is restricted by zero line, whereas the rest of formations are not limited in the western edge of the study area, but continue westward.

The sand -shale ratio map of the Wingate Sandstone (Fig. 17) is

fairly simple to examine and discuss. The major part of the study area

predominantly consists of sandstone. Some exceptions are evident.

Point 57 represetns about 100 percent shale. This evidence is

also visible for points 53 and 61.

The question arises, how shale was deposited on a positive re-

gion instead of a basin. The reason behind it, is, the sand -shale ra-

tion for point 57 represents only the Rock Point Member. Considering

the origin of the Rock Point Member, as mentioned prior, deposited in

a subaqueous lagoonal environment (Harshbarger et al. 1957) ,or alter-

natively it formed as a result of cycles of shallow lacustrine and

eolian depositional (Stewart et al. 1972b) the data became clear. After

Rock Point time as weill be discussed later, no deposition occurred in

this region either because it became a highland or it was eroded prior

to deposition of the overlying units.

For the detailed cross sections of the Wingate Sandstone, first

the southern west -east section (Fig. 12, A) will be examined. The sec-

tion coincides with the isopach map and the unit notably thins eastward.

The west part of the section prominantly consists of the Rock Point Mem- ber, so that its thickness is more than five times that of the Luka-

chukai Member for columns 20 and 18. The Rock Point Member shows LEGEND I 33 66 Arizona Utah li Index number z/ lo5 17 A6 3! Li l whereRatioIsopach Contourinferred line dashed es sty 0 it 141 A 0 20 60 100 kilometers Figure 17. Sand /Shale Ratio Map of Wingate Sandstone. 42

dramatic thinning toward the east, because of which it is not seen from

point 25 eastward, and the Lukachukai Member represents the entire

Wingate Sandstone. The Rock Point indicates more shaley material in

central part of the section and grade into more sandy sediments to both

sides.

The eastern southeast -northwest section (Fig. 12, B), indicates

the thickest part of the Rock Point Member is in the central part. The

Lukachukai thickens northwestward and the greatest thickness for the

entire Wingate is in the central part of the section.

The northern west -east section (Fig. 12, C), represents thinning westward for both the entire Wingate and its individual members.

The Lukachukai Member, except in column 29 which shows about

15 meters of shale and column 238 in which is not differentiated, is

entirely sandstone.

The Rock Point Member represents both sandstone and siltstone,

but toward the west grades more sandy strata, so that column 27 and 3

entirely consist of sandstone.

For the western southeast -northeast section (Fig. 12, D), data

do not include the Wingate Sandstone except for columns 85, 79, and 78 which represent the unit completely. The entire unit consists of sand-

stone, and the thickness decreases from about 25 meters at point 85 to

about 5 meters for point 78.

Moenave Formation

According to Harshbarger and others (1957), on the basis of the metamorphic minerals contained in the Moenave formation, thesource of 43

the Moenave Formation was east of the study area. Study of differences

in thickness and of facies indicate a roughly southwest basin axis

trend.

Johnson (1967) indicated two facies for the lower member of

the Moenave Formation, the Dinosaur Canyon: an eastern eolian facies

deposited by winds blowing from the northwest; anda western fluvial

facies deposited by streams flowing northwest.

The upper member of the Moenave Formation, the Springdale Sand-

stone Member, recognized by Wilson (1974) as of fluvial origin, was de-

posited by streams flowing southwestward.

Fig. 18 shows the index map of the Moenave Formation. Although,

the Moenave Formation has been deposited as three different facies, as

was mentioned above, its isopach map (Fig. 19) seems fairly simple to

examine and discuss. In general, it shows a westward thickening to a

maximum of 118 meters at point 10. West of a line with a south -north

trend across point 10, the Moenave Formation thins to 55 meters at

point 85. The unit also thinning eastward to zero meters.

Referring to the two 100 contours within the study area, that

thin to both sides, one can be certain of the existences of facies

changes along a line that extends across point 16.

Note that the Moenave Formation thins eastward to the zero line

due to facies changes, but toward the west the minimum thickness is

55 meters. Which as stated above, extends toward major basin.

Both point 85 and point 205 indicate ridge or prong and also both show a fairly high slope toward the centra part of the studyarea. LEGEND Index number 45 TN Arizona Utah NewColorado Mexico Thickness 264 3.1 facies ratio 1,204- Li 7Bw >f i1 fro 1,4 ollco 0 20 60 100 kilometers w40 IL1 14 1:`4, dq+1 ie0siÑ. 3 101 M il* 18 P s,4-+ o1 116+2,4, O- Figure 18. Index Map of Moenave Formation. LEGEND Arizona Utah ColoradoNew Mexico 71 Index number i whereIsopach inferred line dashed 7 Contour20 meters interval f j so it 'co too ' SO kilometers 6: 9 20 . 6 0 . 100 I / 8+ 15 1I k \ r ¡I 1 \ \ 8p1 \ \ \ ". ... eo;: Figure 19. Isopach Map of Moenave Formation. 46

The sand -shale ratio map (Fig. 20) indicates the high percentage of sandstone within the study area. The minimum ratio is 1.2 for point 8. The next minimum ratios are 1.8, 3.1, and 4.6 for points 10,

246, and 85 respectively. The rest of the area consists of at least

96 to 100 percent sandstone.

Points 8, 10, 247 and 85 contain more shale presumably due to the existence of some lenticular shaly deposits either were deposited on flood-plains or by local slow fluvial deposition, or both.

Detailed cross section of the Moenave Formation (Fig. 12) show coincidence with the isopach map. The southern west -east (Fig. 12, A) section represents the Moenave Formation only from points 236 through point 21. Point 18, which is situated to the southeast of point 236, indicates an unconformity at the top of the Wingate Sandstone which means that either the Moenave was no deposited in this region or it was eroded prior to deposition of the overlying strata.

The eastern southeast -northwest section (Fig. 12, B) does not consist of the Moenave Formation, but the Kayenta Formation directly rests on the top of the Wingate Sandstone, means facies changes occured in this region.

In the northern west -east section (Fig. 12, C) the Moenave For- mation starts somewhere after point 31 and thickens westward to 112 meters at point 4.

The two members of the Moenave Formation, the Dinosaur Canyon

Member (lower) and the Springdale Sandstone Member (upper) are not differentiated in points 216 and 236 of the southern east -west section and , at toyj. 2 Arizona Utah ColoradoNew Mexico X 1 LEGEND 231 I f4 Index number l 14 4 Ratio Contour % JIlk ; reInferred zero Isopach line fa 0 20 1 60 100 kilometers Figure 20. Sand /Shale Ratio Map of Moenave Formation. 48

point 205 of the northern east -west section. These are subsurface

control points and lack of sufficient variety in lithology make that

impossible to differentiate the two members.

Finally the Moenave Formation is present in the western

southeast -northwest section (Fig. 12, D) more than any other three sec-

tions that were discussed earlier. In this section the Dinosaur Canyon

Member includes the entire Moenave Formation. So, the Springdale

Sandstone Member does not exist in this region. Consequently, the

Springdale Sandstone Member is restricted to the northwestern region of

the study area.

Kayenta Formation

The index map of the Kayenta Formation is shown in Fig. 21.

The Kayenta Formation attains its greatest thickness within the southwest part of the study area at point 12, at which place it is more than

200 meters thick (Fig. 22) . It thins to the east and north of this

area to which a zero line. According to Wilson (1974), the eastward

pinch out is due to erosional truncation at the base of Jurassic rocks.

Two notable features are evident on the isopach map. One, a

small basin situated around point 220 in the northeast of the map. Con-

sidering the basin, its eastern flank is thickened to a great extent

than the other flanks.

The other features are almost an open end basin across point 12

and point 233 with a trend of almost north -south. This feature indi-

cates rapid thickening toward the southeastern flank, which is due to 3 4" z.21 16 log c .1.4 2131 118 34 Arizona Utah ColoradoNew Mexico 4co20 gs t mbl TA e 2W1 36a, 16311.4 2e Z 6 3 2a1+ 251 UI1.3 Zj O vis 611. . t.l . il 120.1171 9 6 s 2 m A8i 1,12e 2 43 Pn,is1 2.1 LEGEND roODrin r 1184.L L 2.11 Index number 45 11 e Thickness 2b4 3.1 facies ratio 1' OD .or 1 0 20 60 100 kilometers Figure 21. Index Map of Kayenta Formation. N 4o . . . . % I" .. . 133 , Utah Colorado ... 4 / 24 218 Ar zona ew Mexico LEG END i l', 1 2 90 . 71 Index Number 2oj . J31 HsuJog ì3o VI j° 214\ / .1 whereIsopach inferred line dashed 120 16 ,0 2,07 7710 / / 40Contour meters interval 2N/ o 20 60 100 kilometers \ \ 2 Figure 22. Isopach Map of Kayenta Formation. 51 facies changes, until contour 40. From contour 40 toward east the rest of the basin shows a gradual change in thickness, meaning that deposition has possibly occurred withoutany tectonic activity.

The sand -shale ratio map of the Kayenta Formation (Fig. 23) comprises both fluvial and eolian deposits, therefore the interpretation is not easy.

The Kayenta rocks were deposited by streams flowing toward the southwest (Wilson 1974). According to Harshbarger and others (1957), the Kayenta streams were forced progressively eastwardacross the study area by the advance of dunes, and causes the mixture of fluvial and eolian deposits through the Kayenta time.

Two unusual occurrences, one around point 31 in northeastern most corner of the area and the other around points 202 and 208, which are located in the northwestern part of the area. These features show more shale, presumably owing to flood plain deposits. Presumably the same explanation is true for points 21 and 205. The rest of the area represent sandstone which probably consist of either fluvial or eolian deposits owing to the stream flowing and wind blowing or both.

In the detailed cross sections (Fig. 12) the southern west- east section (Fig. 12, A) is conformable with the isopach map, as it thins eastward to a zero line.

The eastern southeast -northwest section (Fig. 12, B) also coincides with the isopach map, representing thickening to the northwest. N de i i qoP ....' IIIP Utah Colorado LEGEND 1 I ' I i i q . - rr 1 Lö Arizona New Mexico 71 Index number 17 r e / RatioInferred Contour isopach o 210I Lkf 74 e zero line IL t`.4 r 1 o 20 60 100 kilometers Zit n o / , \ l Figure 23. Sand /Shale Ratio Map of Kayenta Formation. 53

The northern west -east section (Fig. 12, C) showsa similar situation to the isopach map in that it is thicker in the middle and thins to both sides which is due to facies changes.

A problem arises for the last section, the western southeast- northwest section (Fig. 12, D) which apparently is not conformable with the isopach map because the isopach map shows continuation westward but in the detailed cross section disappear. The fact is points that have been located in this section are gathered from reference

(Johnson 1967) that does not include those formations younger than the

Moenave. Consequently, although the Kayenta Formation does exist in the area, it is not in the cross section because of lack of data.

Navajo Sandstone

In the area of this study, the Navajo Sandstone is the thickest formation in all formations of the Glen Canyon Group. The Navajo Sand- stone index map displays as Fig. 24. The isopach map of the Navajo

Sandstone is simple to study (Fig. 25). It attains its greatest thickness in the north and northwest part, where it's about 300 meters thick. It thins southward and eastward gradually, to zero line. Ac- cording to Wilson (1974) it shows an erosional pinch out along a southwest -trending line extending from Four Corners to west of the

Hopi Buttes.

The interesting feature in this area is a trough across points

209, 211, and 215. This trough from east and west is surrounded by two ridges or prongs. The western flanks of the trough represents dramatic thickening owing to the changes in f ac ie s . p,14+ Arizona Utah ColoradoNew Mexico 2S 4 L aD toí 14 ao -o 11 ...7i lb9- .w 238+ Lt a LEGEND Mlog,e°' . ri'1+a.iiiw 1 N/ o 2s i1o.lotpo;'a io+i mr ti Index number 45 Thickness 264 3.1 facies ratio .o cc N 0 20 60 100 kilometers is Figure 24. Index Map of Navajo Sandstone. LEGEND 2et Utah ColoradoNew Mexico 1% Index number whereIsopach inferred line dashed Contour50 meter interval o 20 60 100 kilometers Figure 25. Isopach Map of Navajo Sandstone. 56

The ratio map of the Navajo Sandstone (Fig. 26) represent almost all sandstone with the exception of three control points. Ac- cording to Poole (1962) the Navajo Sandstone is of eolian origin deposited by wind blowing from the north and northwest.

The Navajo Sandstone does not appear in the southern west -east detailed cross section (Fig. 12, A) which coincides with the isopach map.

The eastern southeast -northwest detailed cross section

(Fig. 12, B) exhibits the Navajo Sandstone from column 220 eastward to column 24, and like the isopach map, shows the unit thickening northwestward.

From column 4 eastward to column 219 in the northern west -east detailed cross section (Fig. 12, C) the Navajo Sandstone exists but is not shown in column 3 due to lack of data. The unit thins to zero thick toward the east.

Owing to lack of information, the western southeast- northwest detailed cross section (Fig. 12, D) does not show the Navajo Sandstone, although the isopach map indicates it continues westward. Utah Colorado LEGEND 10.1 tu 231 is Arizona New Mexico 1 Index number só dashedIsopach where zero inferred line 8 201 t ;1 p 2oß lol tlo I / Ratio Contour t10 tog 141 P, JP ` Il 111 L4 6 0 20 69 - kilometers 1 . 1 . . las jl, Figure 26. Sand /Shale Ratio Map of Navajo Sandstone. CHAPTER 4

CONCLUSION

Northeastern Arizona throughout Triassic and Early Jurassic time, was the site of either erosion or Terrestrial deposition. During deposition of the formations in Lower and Middle Triassic, the area was occupied by a transgressive- regressive cycle that caused shallow marine and fluvial deposition. Stream transport was to the west and northwest. Rapid facies changes indicate more fluvial deposits within the southern part of the area than in the northern part.

By the beginning of Chinle time parts of Utah, ARizona, New

Mexico, and Colorado including the study area, generally subsided and formed an irregular shaped basin (O'Sullivan 1977). Also the area was under the influence of stream systems flowing from Mogollon Highland

(Stewart et al. 1972b, Poole 1962). The basin covered the Defiance uplift that in MOenkopi time was a positive area. In addition to the west central part of the region which shows the maximum deposition, the southern part of the region also displays a notable thickness. Consid- ering the position of the southern boundary of the Chinle Formation, which is close to the Mogollon Highland, the source area for the Lower

Chinle was noted by Stewart and others (1972b) and Poole (1962) and its great thickness, probably the Upper Triassic was laid down in a trough with an axis not far from southern limit of the formation. Unlike the

58 59 lower part of the Chinle Formation the origin of itsupper part, the

Owl Rock Member, is clear, and it representsquiet lacustrine deposition. The Owl Rock is less apparent in the southernpart of the region rather than elsewhere owing to latersubsequent erosion. By the end of Late Triassic the Lacustrine environmentof Owl Rock time was restricted to a possible lagoon that occupiedthe northeastern Arizona

(Harshbarger et al. 1957) and in which the ChurchRock and the Rock

Point members were laid down ina quiet -water environment. In general, the Chinle Formation as displays highest percentages of shale in southeastern part of the area (Fig. 10) which is closeto the source area compared to other parts. A possible reason for the increase in clay size material toward the inferred sourcearea might be the alteration of sand size tuff fragments to bentonitic clays after deposition.

The Glen Canyon time begins with the Rock Point basin that toward the Lukachukai time regress westward. So that the other formations in the Glen Canyon Group in northeastern Arizona were laid down in the almost half of the area that was occupied by the Rock Point.

Meanwhile the Defiance uplift again, after the Wingate time, was a positive area that was not covered until the end of Glen Canyon time; this uplift most probably started from point 57, which presumably represents the highest region. Another difference is apparent between the western limit of the Wingate Sandstone and the other formations in the Glen Canyon Group, namely that the Wingate Sandstone is restricted by pinch out in the west whereas the rest of the formations are not 60 limited in the western edge of the studyarea, but continue westward.

Unlike the normal situation, point 57, which indicatesa positive area, represent more shale than sand compare to elsewhere with low elevation. This is due to the Rock Point Member which is formedsome- where prominantly from siltstone.

After the Wingate time, origin of the depositare restricted only to fluvial and eolian environments.

The Moenave Formation pinches out eastward,so that the Kayenta

Formation directly rests on the Wingate Sandstone,means either that no deposition occured, or more probably that the Moenave is time equivalent to parts of both the Wingate and the Kayenta Formations.

The Kayenta Formation is more extensive eastward and less toward north than the Moenave Formation, and was deposited by stream flowing southwestward. The formation also thickens toward the southwest where it shows its greatest thickness.

Eolian deposition, entirely, persisted through Navajo time and formed the last formation of the Glen Canyon Group. This unit attains its greatest thickness, about 300 meters, northwestward and pinches out to the southeast. APPENDIX A

INDEX TO LOCATION OF CONTROL POINTS AND SOURCE

OF DATA

61 Locality Locality Name Number 1 Mouth(Measured of Nokai Sections) Creek San JuanCounty Location13-4.0-3.5(A) in County Arizona State Land Dept.1964 Source of Data 2 Piute Canyon Navaj(Utah) o 25- 10.4 -10.8 11 tt11 11 tttl 11tt 34 LeesNavajo Ferry Canyon 11 Coconino 11 29-26 -2.34.5 -8.5-15.4 11Itil Ittt 1ttt It1t 11tt 65 11 It 29-29 -5.56.5 -9.5-10.2 11tt tI 11tl 11 11tt 7 Lowery Spring 29- 11.0 -12.0 11tlIt Itt it11It II 89 Cedar Ridge 11 tt 61-0.4-7.844 -5.0 -16.8 ttli 11 11It It 1110 MarbleWillow SpringsPlatform 7978- -7.9 7.55 -12.3 -5.25 Ittt 11It 11It ItIt 11tt11 1312 MoenkopiDinosaur Wash Canyon 98-12.1-6.397- 12.5 -10.5 Ittt 11 Ittt tl11tt 11 1514 Black Point 11 11 117-116 -12.04.5 -5.0 -1.0 tt 11tt 11 titI 11It 1716 BarrelTovar MesaButte Navaj o 113114 -9.5-7.5 -14.0 tl It 11 11 tt 1819 CastleIndian WellsButte 11(t 129-5.9-15.0128- 3.2 -6.5 11tt tttI lt 11ti tIttIt 2120 Montezuma'sChimney Rock Chair 11It 129-14.0-6.5130- 1.2 -3.7 tl 11It It11tt 11 tI 22 Monitor Mesa 11 San(Utah) Juan 11 12- 10.5 -1.7 11tt 11It 11 11 11It 23 tt 22-12- 10.511.0 -15.0-5.0A 11 t111 1t tt It 262524 OwlDennehotso Rock tl ApacheNavaj o It 2422- -1.24.8 -1.5-10.8 It11 11 11/1 11 tt Locality Number Locality(Measured Name Sections) County Location in County Source of Data 2827 BetataComb WashKin MontezumaNavaj o 324 -6.4 -1.2 -16.0 -10.8 Arizona State Land Dept. II11 fl It 11 1964 ttIt 3029 LosCathedral Gigantes Rock Apache fl11 36-7.7-7.235- 5.5 -8.0 II ttI1 It Ittt IIIt 3231 RockNzlini Point 11II 90-36- 10.510.0 -7.5-0.2 tl 11tl flIt Itft 1ffl 3433 RoundLittle Rock Round Rock 1Ifl 53-36 5.0 -0.5 -15.7 IIIl 11It 11 If ifII 373635 CoveRed Rock San Juan 11 683534- -0.5-11.0 5.43.0 -13.0 -12.5 ffIt 11II I111 IIff IIIt 38 ToadlenaTodilto Park (N. Mex.) 10588- 9.0-6.0 -4.0 -17.0 ftII ftIt It11 fltl tifl 3039 FortStaple Wingate McKinley it Forsoutheastdepot, Wingate 9 miles ofordance Gal- east 41 II Forthlupeasttion,2 miles -southeastWingate 10 southmiles Sta- of of ft Gallup120- 9.0 -0.6 If If fift Iftt 4243 Thoreau It flIt 120-136- 12.0 9.0 -5.OA-2.5 it11 ti11 f1 f11 ft 464544 TwinKlagetohCheechilgeetho Buttes ApacheNavaj o 127-125 -13.06.5 -8.0 -1.2 If11 it11 IfIf 111f t1ft Locality Number Locality(Measured Name Sections) County Location in County Source of Data 4847 St.Chee MichaelsDodge School Apache 108-69 -3.0 4.47 -11.0 -10.20 Arizona State Land Dept. 1964 11 11 11 11 ,1 5049 PineLupton Springs ,1IT 124-124 -3. 9.4 7 -2.6-11.6 IT11 111, ITTI ITIT 11 51 Holbrook Navaj o milesColoradoSouth south of River,theof Hol-Little 2 1 11 1, /1 IT 5352 Black Mountain Wash Apache Approx:brook36° 21'N 109° 40'W; Stewart et al. (1972a) 54 Chee Dodge San(N. Juan Mex.) Approx:36° 07'N 109° 03'W; 11IT 11 It11 IT11 55 Horse Mesa Creek Apache Approx:36° 42'N 109° 05'W; ,11 11 11 56 PostLukachuka: Trading Approx:36° 26'N 109° 11'W; 11 ,, 11 1, 57 Lupton Approx:35° 18'N 109° 03'W; ,1 ,, 11 11 58 SectionNazilini A Trading Post Approx:35° 50'N 109° 32'W; 11 11 IT 59 OwlBlack Rock Point Section NavajCoconino o Approx:35° 44'N 111° 17'W; 11 ,1 It /1, 60 Zuni Section B McKinley Approx:Sec.36° 50'N36, T. 10 N., 110° 16'W; 11 11 If 11 61 Toadlena San(N. Juan Mex.) R.108° 19 W56'W; 36° 17'N 11 1, 11 11 Locality Number Locality(Measured Name Sections) County Location in County Stewart et al. (1972a) Source of Data 6263 BearsComb EarsWash San(N. Juan Mex.)" " R.109°Sec. 19 E.39'W;30, T. 37 36 S., 19'N "It " " If 6564 MonitorHite Butte " " Approx:110°37° 47'N 26'W; 37° 14'N 110° 30'W; fl It It"It "" 6667 PonchoRincon House Section A IfIt " Approx:37°37° 7'N 19'N 110°109° 47'W;45'W; " " " " 6968 CombOwl RockWash SanNavajo(Utah) Juan Approx:37°36° 19'N52'N 109°110° 39'W;14'W; Stewart et al. (1972b) " " " " 7170 MonitorPoncho ButteHouse "" It" Approx:37° 8'N13'N 109°110° 45'W;26'W; " "If " " 7372 GraseKachina Mesa Point Section Navajo If Approx:35° 33'N 110° 54'W;53'W; Johnson (1967) If If 7574 GraseDinnebito Mesa Wash " Approx:Approx:35° 36'N 110° 57'W;54'W; "It "" 76 Dinnebito Wash " Approx:35° 39'N38'N 111° l'W; If " LnCN Locality Locality Name Number 77 Moenave(Measured Sections) Navaj o County Approx:Location in County 111° 19'W; Johnson (1967) Source of Data 7879 WardMoenkopi Terrace Approx:36° 7'N6'N 111° 19'W;20'W; f 8180 DinosaurSection NineCanyon Approx:35°36° 39'N2'N 111° 3'W;17'W; if1 8382 WardDinosaur Terrace Canyon Approx:Approx:35° 58'N35'N 111°111° 32'W; 6'W; 11 8485 BuckGray MountainRodgers Trading Approx:35° 42'N46'N 111° 13'W;l0'W; f 8786 Lee'sPaintPost FerryPot Section Section Coconino 3/4Cedar1350 mile 50'Nmile Ridge S 60°downstream E of Wilson f (1956) 88 Cameron Section IIf 5riverfrom miles Lee'sgauge S 70°Ferry E of f f 89 Owl Rock Section 11 Owl1Cameron mile Rock NT.P. 45° E of Locality Number Locality(Measured Name Sections) County Location in County Source of Data 90 Skeleton Mesa Section Coconino IV of14.5 Kayenta miles N 50 W Wilson (1956) 9291 RoundM.P. 486Rock Section Lukachukai Apache Across2-348689 near miles Highway Mile north PostU.S. to Il II 9493 WinslowNazliniSection Section Navaj o Il Aboutof2north -4 NazliniS. 12miles 66of miles andLukachukai SE CastletoNE WNW 95 Mile Post 503 Section Coconino nearAdjacentthroughButte(on Mile turnRoad to hogPost ofU.S. Junctionback road503 89 II II 96 Mile Post 501 Section It MileCrossedridge) Post U.S.501 at89 near 11 Il 97 Mile Post 493 Section 11 Sectiontoroughly highway runsright roughly angles II tt Mileperpendicular494.89 Postsmidway 493 between andto U.S. Locality Number Locality(Measured Name Sections) County Location in County Source of Data 98 Mile Post 488 Section Coconino U.S.tweenperpendicularSection 89 Milemidway is Postroughly be-to 488 Wilson (1956) 202201 Coconino It 60-and59 13.10489.-12.50 -2.55 -3.20 Arizona(1964) State Land Dept. It It II I, 204203 NavajoCoconino 26-25- 1.054.05 -5.05-15.25 ItII II11 IIIIt, ItII 206205 Navajo " 40-40 12.25-6.90 -16.95-1.10 11It II 208207 Coconino u 60-59-7.45-11.50 1.50 -8.75 11II 11 210209 11It 77-7.95-5.7077 -1.65 -3.45 It 11It 11 11 212211 Navajo 13096- -13.3510.65 -10.95-16.15 I,It 11ItIt I, It 214213 NavajoCoconino 115113144-5.70-1.25 -0.10-11.40 -0.30 -5.75 IIIt It11 217216215 NavajoCoconino 129129 -7.65 -12.15 -17.00 -2.45 II 11It It 11 219218 Apache 11" 35-21 -7.359.65 -1.80-9.35 11It II11 11II It 221220 u11 36-71 10.8-12.45 -11.50 -14.40 11 11II Locality Locality Name Number (Measured Sections) County Location35- 7.15 -10.40in County Source of Data 223222 Apache 105 -12.40 -15.15 Arizona(1964) State Land Dept. " it 225224226 McKinleyApache u 91-122106 -1.9511.55 -8.45 -2.20-11.50 -15.20 "u " "ItIf "IfII 229228227 "I f 138124-110 -4.10 -11.906.30 -0.65-12.25 -13.60 "" "If " "" 232231230 Coconino II" 60-43-42 -13.653.758.30 -3.70-14.00 -16.85 " "If If"It II" 235234233 SanCoconino(Utah) Juan 'f 115-98-14- 8.702.45 13.0 -15.90-16.10 -1.OA Itu ifn uII "II 238237236 ApacheNavajo If 21-22-129 2.305.35-6.30 -16.30-10.70 -3.35 u uII u " 241240239 "IfIl 125125-53- 11.45 -12.013.85 -1.90 -16.OA-5.65 uIf " IfII" " 244243242245 IlIIf'If 138138-125124 -10.60-1.00-12.500.5 -1.5A -12.95-4.30-14.95 u"If nIf" "If "" LocalityNumber Locality(Measured Name Sections) County Location in County Source of Data 247246 ApacheNavajo R.Sec. 1723 335E. T. 3130 N., Log No. D299 -2597 -R LIST OF REFERENCES

Arizona State Land Department, 1964, Geohydroloái'c data in the Navajo and Hopi Indian Reservations, Arizona, New Mexico, and Utah, Part III, selected lithologic logs, drillers' logs, and stratigraphic sections, Water Resources Report, Number Twelve -C, 157 p.

Freeman, W. E. and Visher, G. S., 1975, Stratigraphic Analysis of the Navajo Sandstone: Journal of Sedimentary Petrology, vol. 45, No. 3, p. 651 -668.

Green, M. W., 1974, The Iyanbito Member (A New Stratigraphic Unit) of the Jurassic Entrada Sandstone, Gallup- Grants Area, New Mexico: Geological Survey Bulletin, 1395 -D, 12 p.

Green, M. W., and Pierson, C. T., 1977, A summary of the stratigraphy and depositional environments of Jurassic and related rocks in the San Juan Basin, Arizona, Colorado, and New Mexico, in New Mexico Geol. Soc. Guidebook 28th Ann. Field Conf., San Juan Basin III, northwestern New Mexico, 1977: p. 147 -152.

Gregory, H. F., 1950, Geology and geography of the Zion Park region, Utah and Arizona: U.S. Geol. Survey Prof. Paper 220, 200 p.

Harshbarger, J. W., Repenning, C. A., and Irwin, J. H., 1957, Stratig- raphy of the uppermost Triassic and Jurassic rocks of the Navijo County: U.S. Geol. Survey Prof. Paper 291, 74 p.

Imlay, R. W., 1952, Correlation of Jurassic formations of North Amer- ica, exclusive of Canada: Geol. Soc. American Bull., v. 63, p.953 -992.

Johnson, A. H., 1967, Stratigraphy and Paleoenv ironment of the Dinosaur Canyon of the Moenave Formation (Upper Triassic ?) in the southern part of the Navajo and Hopi Indian Reservations, Arizona: Univ. of Arizona, M.S. thesis, 123 p.

O'Sullivan, R. B., 1970, the upper part of the upper Triassic Chinle Formation and related rocks, southeastern Utah and adjacent area: U.S. Geol. Survey Prof. Paper 644 -E, 22 p.

, 1977, Triassic rocks in the San Juan Basin of New Mexico and adjacent areas, in New Mexico Geol. Soc. Guidebook 28th Ann. Field Conf., San Juan Basin III, northwestern New Mexico, 1977: p. 139-146.

71 72

Poole, F. G., 1961, Stream directions in Triassic rocks of the Colorado Plateau, in Geological Survey research 1961: U.S. Geol. Survey Prof. Paper 424 -C, p. C139 -C141.

, 1962, Wind directions in late Paleozoic to middle Meso- zoic time on the Colorado Plateau, in Geological Survey research 1962: U.S. Geol. Survey Prof. Paper 450 -D, p. D -147- D151.

Schultz, L. G., 1963, Clay minerals in Triassic rocks of the Colorado Pleateau: U.S. Geol. Survey Bull. 1147 -C, p. Cl -C71.

Stewart, J. H., Poole, F. G., and Wilson, R. F., 1972a, Stratigraphy and origin of the Chinle Formation and related upper Triassic strata in the Colorado Plateau region with a section on Sedi- mentology petrology by R. A. Cadigan, and a section on Con- glomerate studies by William Thordarson, H. F. Albee, and J. H. Stewart: U.S. Geol. Survey Prof. Paper 690: 336 p.

, 1972b, Stratigraphy and origin of the Triassic Moenkopi Formation and related strata in the Colorado Plateau region, with a section on Sedimentary petrology by R. A. Cadigan: U.S. Geol. Survey Prof. Paper 691, 195 p.

Stewart, J. H., Williams, G. A., Albee, H. F., and Raup, 0. B., 1959, Stratigraphy of Triassic and associated formations in part of the Colorado Plateau region, with a section on Sedimentology petrology by R. A. Cadigan: U.S. Geol. Survey Bull. 1046 -Q, p. 487 -576.

Wanek, A. A., and Stephens, J. G., 1953, Reconnaissance geologic map of the Kaibito and Moenkopi Plateaus and parts of the Painted Desert, Coconino County, Arizona: U.S. Geol. Survey Oil and Gas Env. Map 0 M -145, scale 1:150,000.

Wilson, R., 1956, Stratigraphy and geology of the Chinle Formation, northeastern Arizona: Univ. of Arizona, Ph.D. thesis, 142 p.

Wilson, R. F., 1974, Mesozoic Stratigraphy of northeastern Arizona, in Geological Soc. of America, Geology of northern Arizona with notes on archaeology and paleoclimate. Part 1- Regional studies. Rocky Mountain Sec. Meeting, Flagstaff, Arizona, p. 192 -207.

Witkind, I. J., and Thaden, R. E., 1963, Geology and uranium- vanadium deposits of the Monument Valley area, Apache and Navajo Coun- ties, Arizona: U.S. Geol. Survey Bull., 1103, 171 p. LEGEND i"ige7- Crss Seotionsof the Moenkopi Formation SandstoneShale Conglomerate 213 W zn E SE NW 60 100 kilometers 241 Z93 o A -- Detailed cross section showing correlation of Moenkopi B - Detailed cross section C - Detailed cross section showing D - Detailed cross section Formationto point in223. southern west -east section, from point 213 eastMoenkopipointeasternshowing section, 25 Formationnorthwest- correlationto pointfrom in22.south- of correlationpointin northern 6 to of pointwest Moenkopi -east26. section,Formation from pointeastMoenkopishowing section,15 correlationtoFormatione;tern point from northwest- 11. inof south- 61 Fig.11- Cross W E SE -Sections of the Chinle Formation NW W E SE NW 0 LEGEND IH 37 ShaleLimestone 92 2p 60 100 kilometers SandstoneConglomerate zzl

Moenkopi Moenkopi Moenkopi A - Detailel cross section showing correlationpointFormation of217 Chinle toin pointsouthern 43. west -east section, from B - Detailed cross section showing correlationFormationfrom pointof inChinle 61eastern to point northwest 64. -southeast section, C - Detailed cross section showing correlationsection,of Chinle fromFormation point in87 northernto point west222. -east D - Detailed cross section showing correlation95.southeastof Chinle Formationsection, fromin western point 14northwest to point - 197,r E Figlt--Cross -Sections of the Glen Canyon Group SE 31 NW 5- 31 Z56 21 i. LEGEND Z10 Naval. shaleLimestone 55- ConglomerateS ands tone 33 Navajo la o2- 6 35 9 20 60 100 kilometers 16 46 38 , 111 Cd si 21.1 siz 39 q3 Owl Rock Owl Rock aO Owl Rock A - Detailed cross section showing correlationGroup in of souther'-west-east Glen Canyon section, from point 21 to point 43. B - Detailed cross section sBowin correlationpointGroup of 38in Glen toeastern point Canyon northwest-southeast24. section, from C - Detailed cross section showing correlationin northern of 'lien west-east Canyon groupsection, from point 4 to point 35. D - Detailed cross section showir0 correlationtion,in western from ofpointnorthwest-southeast Glen 72 Canyon to point Group sec- 78.