A reconnaissance of mesozoic strata in nothern Yuma County, southwestern Arizona Item Type text; Thesis-Reproduction (electronic) Authors Marshak, R. Stephen Publisher The University of Arizona. Rights Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. Download date 06/10/2021 05:01:15 Link to Item http://hdl.handle.net/10150/566541 A RECONNAISSANCE OF MESOZOIC STRATA IN NORTHERN YUMA COUNTY, SOUTHWESTERN ARIZONA by R. Stephen Marshak A Thesis Submitted to the Faculty of the DEPARTMENT OF GEOSCIENCES In Partial Fulfillment of the Requirements For the Degree of MASTER OF SCIENCE In the Graduate College THE UNIVERSITY OF ARIZONA 1 9 7 9 STATEMENT BY AUTHOR This thesis has been submitted in partial fulfillment of re­ quirements 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 scholar­ ship. In all other instances, however, permission must be obtained from the author. SIGNED: APPROVAL BY THESIS DIRECTOR This theses has/b^en approved on the date shown below: ?.J. CONEY/ Professor of Geology ACKNOWLEDGMENTS I am grateful to the members of my committee, Drs. Peter Coney, George Davis, and Wesley Peirce, for their assistance in this project. Support for this research was generously provided by the State of Arizona Bureau of Geology and Mineral Technology, and I am grateful to - the members of the Bureau staff, especially Wesley Peirce, Stanley Keith, and Joseph Lavoie, for their advice and encouragement throughout this project. Gregory McNew, George Sanders, and Robert Schafer, of the Department of Geosciences, assisted with the petrographic studies. Support for the preparation of thin sections was provided from the Bert S. Butler scholarship fund of the Department of Geosciences. I appreciate the information provided by Stephen Reynolds, Ed DeWitt, W. J. Crowell, and Brad Robison, who are or were students of the Department of Geosciences. My sincere thanks are extended to my friends at The University of Arizona for their moral support when it was needed most. Stanley Keith and Paula Trever helped in the field on my last trip there, when the thermometer read 117°F. My appreciation also goes to my parents, Robert and Ruth Marshak, who have encouraged me in all stages of my education.’. Finally, I would like to express my deepest gratitude to my fiancee, Kathryn Collin, who edited and typed four drafts of the manuscript, and without whose love and support this project would never have been completed. iii TABLE OF CONTENTS Page LIST OF ILLUSTRATIONS. ...................................... vi LIST OF T A B L E S ........................ x A B S T R A C T ........................................................ xi 1. INTRODUCTION .................................................. 1 Statement of the Problem ................. History of Geologic Study in Yuma County . H UJ Methodology and Terminology............... 2. THE DOME ROCK MOUNTAINS....................................... 7 Lithologies................................................ 7 Mesozoic Strata....................................... 7 Bounding Terranes..................................... 23 Contact Relations.......................................... 33 Structural Features................................... .. 40 F a u l t s ................................................ 40 Folds.................................................. 41 Other Structural Features.................. 41 Discussion....................... 48 Stratigraphy.................... 48 Structure.............................................. 50 Age Constraints............ 52 3. THE LITTLE HARQUAHALA MOUNTAINS. .............................. 54 Lithologies................................................ 54 Mesozoic Strata.............. 54 Bounding Terranes........................ 60 Contact Relations.......................................... 62 Structural Features....................................... 62 Folds and F a u l t s ..................................... 62 Discussion............ 63 Stratigraphy.......................... 63 Age Constraints....................................... 63 iv V TABLE OF CONTENTS— Continued Page 4. THE GRANITE WASH MOUNTAINS................................... 65 Lithologies................................................ 65 Mesozoic Strata....................................... 65 Bounding Terranes..................................... 72 Contact Relations......................................... 74 Structural Features.......... 74 Folds.................. 74 Faults ........................................ 76 Other Structural Features............................. 76 Discussion.............. 76 Stratigraphy .......................................... 76 Age Constraints........................................ 80 5. THE PLOMOSA, BUCKSKIN, AND NORTHERN DOME ROCK MOUNTAINS. 82 Plomosa Mountains.......................................... 82 Lithologies............................................ 82 Contact Relations..................................... 88 Discussion ............................................ 90 Buckskin Mountains........................................ 91 Lithologies............................................ 91 Field Relations....................................... 94 Discussion............................................ 94 Northern Dome Rock Mountains............................. 95 6. SUMMARY, CORRELATION, AND CONCLUSION......................... 96 Summary.................................................... 96 Correlation.................................................. 103 Conclusion.................................................. 106 LIST OF REFERENCES 108 LIST OF ILLUSTRATIONS Figure Page 1. Location Map of Areas in Yuma County Mapped by Wilson (1960) and referred to on the Geologic Map of Arizona as "Mesozoic Sedimentary Rocks"................ 2 2. Newspaper Report Concerning the Discovery of a New Mountain Range in Yuma County........................... 5 3. Location Map Showing Mapped Areas and Major Contacts Studied in the Dome Rock Mountains..................... 8 4. Distance Photograph of the Central Dome Rock Mountains, Showing Outcrops of Mesozoic Strata..................... 16 5. Schematic Stratigraphic Column and Strip Map of the Eastern Flank of the Dome Rock Mountains.......... (pocket) 6. Schematic Chart Showing the Range of Individual Lithologies in the Section of Mesozoic Strata of the Dome Rock Mountains............................. 17 7. Photomicrograph of Calcareous Quartz Sandstone From the Dome Rock Mountains........................ 18 8. Photograph of Conglomerate Outcrop From Unit A of the Dome Rock Mountains.................................. 19 9. Photomicrograph of Greywacke With Possible Tuffaceous Component. ....................... 21 10. Photograph of Granule Conglomerate Outcrop in the Dome Rock Mountains.......... 22 11. Photomicrograph of the Feldspathic Greywacke of the Dome Rock Mountains................................. 24 12. Distance Photograph of the Meta-Volcanic Terrane of the Dome Rock Mountains................................. 26 13. Photograph and Tracing Showing Contact of Mesozoic Strata With Meta-Basalt on La Cholla Mountain. ..... 27 vi vii LIST OF ILLUSTRATIONS— Continued Figure Page i 14. Reconnaissance Geologic Map of the Copper Bottom Pass Area, Dome Rock Mountains, Arizona ................. (pocket) 15. Photomicrograph of Meta-Crystalline Tuff From the • Dome Rock Mountains...................................... 28 16. Photograph of Coarse Meta-Crystalline Tuff Outcrop in the Copper Bottom Pass Area of the Dome Rock Mountains ....................................... 29 17. Photomicrograph of Dark Grey Meta-Volcanic Macke of Cunningham Mountain, in the Dome Rock Mountains. 31 18. (A) Photomicropgrah of Mylonite Derived From Meta- Crystalline Tuff (B) Photomicrograph of Mylonite Derived From Dark Grey Meta-Volcanic Macke . ............ 32 19. Reconnaissance Geologic Map of the Southern End of the Dome Rock Mountains..................... (pocket) 20. Distance Photograph of Meta-Crystalline Tuff Outcrop at the Southern End of the Dome Rock Mountains .... 34 21. Photographs and Tracing of Dark Grey Meta-Volcanic Macke in Contact Mith Mesozoic Strata.................. 36 22. Photograph of Calcareous Quartz Sandstone — Mylonite Contact........................... ..................... 37 23. Map Showing Bending of Foliation of the Meta-Volcanic Terrane Into Parallelism Mith the Cunningham Mountain F a u l t ........................................ 39 24. Photograph and Tracing of Intrafolial Folds at the Copper Bottom Mine, Dome Rock Mountains................. 42 25. Photograph Showing High Angle Between Bedding and Foliation Planes in a Layer of Calcareous Quartz Sandstone on La Cholla Mountain.......................... 44 26. Equal Angle Lower Hemisphere Projections