THE STRUCTURAL GEOLOGY OF PART OF THE LIMESTONE HILLS IN THE WICHI'IA :-10iJNTAINS, CADDO AND C_OMANCHE COUNTIES, OKLAHOMA By ABDOLALI BABAEI Bachelor of Science Pahlavi University 1975 Submitted to the Faculty of the Graduate College of the Oklahoma State University in partial fulfillment of the requirements for the Degree of MASTER OF SCIENCE May, 1980 THE STRUCTURAL GEOLOGY OF PART OF THE LIMESTONE HILLS IN THE WICHITA MOUNTAINS, CADDO AND COMANCHE COUNTIES, OKLAHOMA Thesis Approved: Thesis Adviser Dean of the Graduate College ii PREFACE The main purpose of this thesis is to map the general geology, and particularly to interpret the structural elements of the limestone hills in the Wichita Mountains, southwestern Oklahoma. The major emphasis of the study is to show the role of regional tectonics and the nature of major fault movements in the area. I would like to offer special thanks to my thesis supervisor, Dr. R. Nowell Donovan, for his constant encouragement and great help in this project. Sincere appreciation is extended also to other thesis commit- tee members, Dr. Gary F. Stewart and Dr. Alex R. Ross, for their helpful / criticism of the manuscript. I am also greatly indebted to Dr. David J. Sanderson for help in the field, and to Dr. Thomas L. Thompson (Professor, Department of Geology, University of Oklahoma) for his helpful comments. My grateful thanks also go to my typist, Ms. Jeanne Vale, for her care and patience with the manuscript. I acknowledge the support of the Department of Geology, Oklahoma State University. Finally, most grateful thanks are due my wife, Sima, who helped me greatly, both in the field and during preparation of the thesis maps and diagrams. iii TABLE OF CONTENTS Chapter Page I. ABSTRACT 1 II. INTRODUCTION 3 Location of Study Area .• 3 Topography and Exposure 3 Study Techniques .... 5 Previous Investigations 6 III. STRATIGRAPHY . 8 Introduction. 8 Rocks of Cambrian Age 8 Carlton Rhyolite . 8 Cambre-Ordovician Rocks 9 The Arbuckle Limestone Group 9 McKenzie Hill Formation . 10 Cool Creek Formation .. 10 Kindblade Formation . 11 West Spring Creek Formation 11 Permian Rocks . 12 Wichita Formation .... 12 IV. STRUCTURAL GEOLOGY OF THE REGION 14 Summary . • . • . .. 14 Principal Tectonic Controls That Affected the Area Studied. 14 The Plate Tectonic Interpretation of Southern Oklahoma. • . 16 Outline of Geological Development in the Paleozoic. 16 Review of Aulacogen ...•.....•.... 18 _ Application of Theory to Southern Oklahoma . 18 Structural Development of the Aulacogen 19 The Problem of Wrench Faults in the Wichita Mountains . • . • • 21 iv Chapter Page v. STRUCTURES MAPPED IN THE SADDLE MOUNTAIN AREA. 25 Presentation. 25 Major Structural Features 25 Blue Creek Canyon Fault 25 Other Faults ...•... 26 Folds • . .. • . • . 30 First Order Folds. 30 Second Order Folds • . 34 Pressure Solution Cleavage 34 VI. AN INTERPRETATION OF THE STRUCTURE OF THE AREA 46 Review of Principal Structural Features . 46 The Anomalous Trend of the Blue Creek Canyon Fault . 48 Fold Generation and Stress Orientation .. 48 Conclusion. 52 Stress Orientation Models ... 52 Limitations of the Thesis .. 53 Suggestions for Further Work . 53 SELECTED BIBLIOGRAPHY 54 APPENDIX. 57 v TABLE Table Page I. Outline of the Development of the Oklahoma Aulacogen. 20 vi LIST OF FIGURES Figure Page 1. Geographical location of area studied . 4 2. Location of principal structural features of southern Oklahoma (from Ferguson, 1979) ..... 15 3. Geology of Wichita Uplift (adapted from Havens, 1977) 17 4. Stages in the initiation of faulting in the southern Oklahoma aulacogen (from Carter, 1979) .•..... 22 5. View northwards in Blue Creek Canyon. 27 6. View northwards of Blue Creek Canyon Fault Complex. 28 7. Deformation associated with the Blue Creek Canyon Fault . 29 8. Anticline in the Cool Creek Formation showing a minor thrust plane developed in the fold hinge. 31 9. First order syncline, plunging northeastward, in the Cool Creek Formation. • . 32 10. First order anticline in the Cool Creek Formation 33 11. Plunging symmetrical syncline showing similar fold style. 35 12. General view to the southeast of the western part of the area studied. 36 13. View to north of northwestward plunging anticline 2,000 ft. west o= Blue Creek Canyon Fault •... 37 14. View to east of fold illustrated in Fig, 13 showing development of structural terrace between two anticlinal axes derived from lower level single anticline to south (right) . • 38 15. Second order folds on northeastern limb of first order fold seen in Fig. 10. •...•.. 39 16. Pressure solution cleavage in hinge of plunging anticline 300 ft. west of Blue Creek Canyon Fault 40 vii Figure Page 17. Stereogram showing bedding attitudes in the area adjacent to the Blue Creek Canyon Fault . 42 18. Stereogram showing bedding attitudes in the western part of the area. 43 19. Data abstracted from Barthelman (1969) from the area of Saddle Mountain west of the area mapped indicates a general similarity with data in Fig. 19; no consistent direction of plunge is apparent. 44 20. Data from Brookby (1969) from the area east of that mapped (and outside the Lawtonka "graben") illustrates that the same fold trend occurs as that in Fig. 18 and 19. The data are weighted as most of the fold exposures are northeasterly-dipping fold limbs. 45 21. Synopsis of attitudes of major structural features in area mapped. Theoretical maximum stress is plotted at 90° to maxiraa of fold. 47 22. Compressional stress. (A) After Anderson (1972). (B) After Wilcox et al. (1973) ..... 50 23. Principal structural features of the area. Scale 1:250,000 51 viii -- --- -- --------------- LIST OF PLATES Plate 1. Geology of Eastern Saddle Mountain 2. Geologic Cross Section, Eastern Saddle Mountain 3. Geology of Blue Creek Canyon Fault Area ix CHAPTER I ABSTRACT Detailed field mapping of the eastern half of Saddle Mountain in the northern Wichita Mountains has delineated a complex of folds developed in the limestones of the Upper Arbuckle Group. The folds trend northwest; the majority plunge in this direction. Two orders of fold magnitude are (a) 600 to 3,000 ft. (first order folds), and (b) 5 to 30 ft. (second order folds). Parallel and similar fold styles are developed in both symmetrical and asymmetrical structures and both open and closed folds exist, the latter showing the development of pressure solution cleavage in hinge regions. Folds are located in the Lawtonka "graben," a complex fault­ controlled structure separated from the Blue Creek Canyon horst to the northeast by the Blue Creek Canyon Fault. The latter has an anomalous trend (NS-10°w as opposed to NS0°w elsewhere) in the area mapped and is a braided fault complex here interpreted as a high-angle reverse fault with a downthrow to the southwest. The folds developed during the final evolution of the southern Oklahoma aulacogen during the Pennsylvanian. The principal stress responsible for folding was N40°E. However, deviation of fold-axis trend in the area of the Blue Creek Canyon Fault suggests secondary compression approximately from N80°E. This compression could have produced reverse movement on the Blue Creek Canyon Fault in the area 1 2 mapped (with anomalous trend) and left-lateral wrench movement elsewhere on the fault. This interpretation is in accord with previous interpre- tation of fault movements in the area based on independent evidence. CHAPTER II INTRODUCTION The objectives of this thesis are: a) production of a geological map of part of Saddle Mountain which is located in Comanche and Caddo Counties in southwest Oklahoma; b) analysis of structure in the area as it affects limestones of the Arbuckle Group; c) determining the effects on this structure of lateral movements postulated along major faults in the area. Location of Study Area Saddle Mountain is one of the Limestone Hills which form the northern flank of the Wichita Mountains in southwest Oklahoma. Boundaries of the area studied are: the southwestern sections of Caddo County in the north, Sec. 23, T3N, Rl2W in the south, Sec. 13, T4N, Rl2W in the east, the eastern edge of Rl3W in the west, and Kiowa County line in the northwest (Fig. 1). The area comprises approximately 23 sq. mi. with maximum dimensions of 6 x 7 mi. Topography and Exposure The Limestone Hills are monadnocks rising up to 1,200 ft. above the general level of southwestern Oklahoma. 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