Stratigraphy of the red chert-pebble conglomerate in the Earp Formation, southeastern Arizona Item Type text; Thesis-Reproduction (electronic); maps Authors Rea, David Kenerson, 1942- 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 07/10/2021 07:43:02 Link to Item http://hdl.handle.net/10150/551936 STRATIGRAPHY OF THE RED CHERT-PEBBLE CONGLOMERATE IN THE EARP FORMATION, SOUTHEASTERN ARIZONA .... David Kenerson Rea A Thesis Submitted to the Faculty of the DEPARTMENT OF GEOLOGY In Partial Fulfillment of the Requirements For the Degree of MASTER OF SCIENCE In the Graduate College THE UNIVERSITY OF ARIZONA 1 9 6 ? 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 per­ mission 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 Judgment 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: n Lj-i/d K ^ A APPROVAL BY THESIS DIRECTOR This thesis has been approved on the date shown below: / > W ^ % ' U 4 DONALD L. BRYANT Date Professor of Geology ACKNOWLEDGMENTS The author wishes to extend his gratitude to Dr. Donald L. Bryant for guiding his work and providing constant encouragement and many helpful suggestions. Dr. Joseph F. Schrelber and Dr. Richard F. Wilson spent time in the field with the author and provided many thoughtful criticisms and enlightening ideas. Dr. Spencer R. Tltley suggested the problem and provided encouragement throughout its completion. The manuscript was read by Drs. Bryant, Schrelber and Tltley, all of whom provided many worth­ while criticisms. Field work was assisted in part by Richard B. Lodewlck, Jon P. Broderick, and L. Clark Arnold. Robert B. Laughon performed several X-ray analyses for the author. Informal discussions among graduate students at the University of Arizona were often quite helpful. The author is especially Indebted to Dr. Charles A. Ross of Western Washington State College who provided Invaluable assistance in the identification of fusulinids. H i TABLE OP CONTENTS LIST OF ILLUSTRATIONS................................ Vl LIST OF TABLES....................................... vi.il ABSTRACT............................................. lx INTRODUCTION....................................... 1 Purpose of Study and Method of Treatment....... Location........................................ CM Cv-CO CM VO VO CM Previous Work................................... Investigations in report area.... ......... Investigations outside the report area.... GEOLOGY OF EAR? FORMATION IN AREAS STUDIED.......... Geologic Setting. Earp Type Section Gunnison Hills... Whetstone Mountains............................ 16 Colossal Cave Area.............................. 23 Patagonia Mountains............................. 2? Swisshelm Mountains............................. 31 STRATIGRAPHY AND SEDIMENTATION OF THE RED CHERT-PEBBLE CONGLOMERATE......................... 34 Lithologic Correlation......................... 34 Paleontologic Correlation...................... 36 Deposition and Possible Sources................ 37 EARP FORMATION TYPE SECTION......................... 40 CONCLUSIONS.......................................... 46 Red Chert-Pebble Conglomerate.................. 46 Earp Formation.................................. 4? SUGGESTIONS FOR FUTURE STUDY........................ 49 APPENDIX............................................. 59 iv V TABLE OF CONTENTS (continued) Introduction........... Measured Sections...... Section I ......... Section II........ Section III....... Section IV........ Section V ......... Section VI........ Section VII....... Section VIII...... SELECTED REFERENCES 114 LIST OF ILLUSTRATIONS Figure Page 1. LOCATION MAP................................ 3 2. LOCATION MAP OF SECTIONS I, II, III, IV, GUNNISON HILLS............................ 9 3* HILL CONTAINING SECTION III, GUNNISON HILLS...................................... 12 4. OUTCROP OF RED CHERT-PEBBLE CONGLOMERATE, GUNNISON HILLS............................ 12 5» CROSS LAMINATIONS, HORIZONTAL LAMINATIONS, AND RIPPLE LAMINATIONS, GUNNISON HILLS.... 13 6. RIPPLE LAMINATIONS, GUNNISON HILLS........... 13 ?• IMBRICATION, CROSS LAMINATIONS, HORIZONTAL LAMINATIONS, GUNNISON HILLS............... 14 8. CROSS BEDDING IN RED CHERT-PEBBLE CONGLOMERATE, GUNNISON HILLS.............. 14 9* LIMONITE CUBES. GUNNISON HILLS............... 1$ 10. LOCATION MAP, SECTION V, WHETSTONE MOUNTAINS.................................. 1? 11. LOCATION MAP, SECTION VI, WHETSTONE MOUNTAINS.................................. 18 12. MUDCRACKS, WHETSTONE MOUNTAINS.............. 21 13. LIMESTONE-PEBBLE CONGLOMERATE, WHETSTONE MOUNTAINS....................... 21 14. LOCATION MAP, SECTION VII, COLOSSAL CAVE AREA........................ 24 15. LOCATION MAP, SECTION VIII, PATAGONIA MOUNTAINS....................... 28 16. CROSS BEDDING IN RED CHERT-PEBBLE CONGLOMERATE, PATAGONIA MOUNTAINS......... 30 vl vll LIST OP ILLUSTRATIONS (continued) Figure Page 17. LOCATION MAP, SWISSHELM MOUNTAINS........... 32 CO i-4 EARP FORMATION TYPE SECTION................. 43 Plate 1. COLUMNAR SECTIONS OF EARP FORMATION, SOUTHEASTERN ARIZONA................. In pocket 2. CROSS-SECTION OF EARP FORMATION, SOUTHEAST ARIZONA TO SOUTHWEST NEW MEXICO........................... In pocket LIST OF TABLES Table Page 1. ANALYSIS OF DIRECTIONAL STRUCTURES.......... 38 2. LOCATION OF FUSULINIDS IN DIFFERENT SECTIONS................................... 42 3. BEDDING TERMINOLOGY......................... 59 Till ABSTRACT The Earp Formation In southeastern Arizona can be divided on the basis of lithology Into three members, the lower limy member, the middle terrigenous member, and the upper interbedded clastic and carbonate member. The red chert-pebble conglomerate is a single, possibly Isochronous, unit within the middle terrigenous member, and forms an excellent marker bed throughout Its area of outcrop. Meandering streams, bringing red chert pebbles south from the eroding Naco Formation in the area of Winkelman and Superior, Arizona, deposited this unit. Some limestone- pebble conglomerates in Earp sections outside the report area may be correlative with the red chert-pebble conglomerate. Fusullnids in the Earp in the report area occur only in the lower limy member. Studies of these fossils indicate a late Vlrgillan to possibly as late as middle Wolfcampian age for this part of the Earp Formation and an early to middle Wolfcampian age for the red chert- pebble conglomerate. The type section of the Earp Formation is atypical. The basal part of the lower limy member and most or all of the middle terrigenous member seem to be missing, probably the result of faulting. lx X The lower limy member of the Earp seems to have a source of elastics in north central Mexico. This member undergoes a gradational facies change to the east, where, without elastics, the same unit probably becomes the upper portion of the Horquilla Limestone of southwestern New Mexico INTRODUCTION Purpose of Study and Method of Treatment For many years workers In southeastern Arizona have noticed outcrops of red chert-pebble conglomerate within the Pennsylvanian-Permian Earp Formation (Gllluly, Cooper, and Williams, 195*+» P« 23; Tyrrell, 1957. P* 65) • Bryant (1955) observed this conglomerate In several areas and suggested a possible correlation. This thesis attempts to solve the problem of whether the red chert- pebble conglomerate Is correlative and isochronous throughout its area of outcrop. Possible source areas for the conglo­ merate and its method of deposition are Investigated. Sections of the Earp Formation containing the conglomerate were measured wherever possible to provide control for lithologic correlation. Fusulinlds were collected and studied In an attempt to provide the most precise age possible for the conglomerate. Current directions were studied by measuring cross-bedding and Imbrication wherever these structures occurred. Outcrops of the red chert-pebble conglomerate were mapped on standard U. S. Geological Survey 7& and 15 minute topo­ graphic quadrangle maps. 1 2 Location Portions of three counties in southeastern Arizona were studied for this report: Pima County, Santa Cruz County, and Cochise County. Five major outcrop areas occur within these three counties (see Fig. 1). In Cochise County these are the Gunnison Hills, the Whetstone Mountains, and the Swisshelm Mountains. The Colossal Cave area lies in Pima County, and the Patagonia Mountains are in Santa Cruz County. Previous Work Investigations in report area Gilluly (in Butler, Wilson, and Rasor, 1938) measured sections of the Naco Formation of Ransome (1904). These sections, measured in the Tombstone area, include what is now the Earp Formation. In 195^. Gilluly, Cooper, and Williams published