Stratigraphy and Environment of the Toroweap Formation (Permian) North of Ashfork, Arizona
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Stratigraphy and environment of the Toroweap Formation (Permian) north of Ashfork, Arizona Item Type text; Thesis-Reproduction (electronic) Authors Mullens, Rockne Lyle, 1944- 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 10:06:59 Link to Item http://hdl.handle.net/10150/554040 STRATIGRAPHY AND ENVIRONMENT OF THE TOROWEAP FORMATION (PERMIAN) NORTH OF ASHFORK, ARIZONA by Rockne Lyle Mullens 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 C ollege THE UNIVERSITY OF ARIZONA 19 67 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 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: APPROVAL BY THESIS DIRECTOR This thesis has been approved on the date shown below: Professor of Geology ACKNOWLEDGMENTS The research, on which this paper is based, was supported by a research grant from the Museum of Northern Arizona and a Special Master's Program grant from the Ford Foundation. Mr. William J. Breed and Dr. Edward B. Danson, Museum of Northern Arizona, and Dr. Stanley S. Beus, Northern Arizona University, generously placed the facilities of the Museum and University at the writer's disposal. Their cooperation is greatly appreciated. The writer is greatly indebted to Dr. Richard F. Wilson, who directed the research, and Drs. Donald L. Bryant and Joseph F. Schreiber. Their critical reading of the paper and many suggestions were invaluable. The writer is as always greatly indebted to his parents for their continual assistance and encouragement throughout his entire education; to them he is forever grateful. TABLE OF CONTENTS Page ACKNOWLEDGMENTS................................................................................... iii LIST OF ILLUST RATIONS............................................................................. vi ABSTRACT.......................................... v iii INTRODUCTION................................................................................................ 1 Purpose and Scope of Investigation ........................................... 1 Location and P h y sio g r a p h y ........................................ .................. 1 Methods of S tu d y ................................................................................ 3 History of Nomenclature of the Toroweap Formation . 10 General G e o lo g y ................................................................................ 15 DISCUSSION OF LITHOLOGIC U N IT S ..................................................... 17 Coconino S a n d s to n e .......................................................................... 17 Toroweap-Coconino C ontact........................................................... 18 Toroweap F o r m a tio n .................................................... 18 Toroweap-Kaibab Contact . ............................................... 21 Kaibab Form ation ............................................................................. 22 PALEO NTO LO G Y........................................... 32 Faunal L is t ............................................................................................ 32 Quantitative Faunal Distribution ................................... 34 "Patch R e e fs " ...................................................................................... 39 MINERALOGY................................................................................................... 40 Authochthonous M inerals .................. 40 Allochthonous Minerals. ........................................ 41 CONCLUSIONS..................... 43 Paleogeography........................... 43 Correlation with Type Section of Toroweap Formation . 43 iv V TABLE OF CONTENTS--Continued Page Environmental Interpretations.................................................... 45 Faunal Interpretations....................................................................... 51 Suggestions for Future Research ................................................. 53 APPENDIX A--LOCATION AND DESCRIPTION OF MEASURED SECTIONS OF THE TOROWEAP FORMATION (PERMIAN) NORTH OF ASHFORK, ARIZONA.............................................. 59 SELECTED REFERENCES 99 LIST OF ILLUSTRATIONS Figure Page •L Index map of the study a rea ................................................. ... 2 2. Classification system for terrigenous clastic rocks (Folk, 1959). ................................................................................... & 3. M ineralogical classification of carbonate r o c k s........................ 5 4. Textural classification of carbonate rocks (Folk, 1 9 5 9 )................................................................................... ................... 6 5. G rain-size sca le for carbonate rocks (Folk, 1959)................ 7 6. Relative fossil-abundance diagram (slightly modified from Belden, 1954).......................................................................... 8 7. Calibration curve for the x-ray determination of the percent dolomite in a carbonate sample (Tennant and Berger, 1957) . ..................................... ..................... 11 8. Isopach map of unit I .............................................. 23 9. Isopach map of unit II. ........................ 24 10. Thickness map of unit III ................ 25 11. Isopach map of unit IV ...................... 26 12. Isopach map of unit V ................ 27 13. Isopach map of unit VI ............ ..................... 28 14. Isopach map of unit VII........................................ 29 15. Isopach map of unit VIII . .................. 30 16. Thickness map of unit IX ........__ ............ 31 vi v ii LIST OF ILLUSTRATIONS--Continued Figure Page 17. "Ndrmal marine" faunal abundance distribution in unit VI . ...................................................................... ................ 35 18. Nautiloid faunal abundance distribution in unit VII ...... 36 19. Gastropod faunal abundance distribution in unit VII ..... 37 20. Pelecypod faunal abundance distribution in unit VII ..... 38 . 21. Paleogeographic map of the time of maximum transgression of the Toroweap Sea . ..................................... 44 22. Selected thin sections.. ................................................. 54 23. Gastropoda...................................................................................... 55 24. Nautiloidea and Pelecypoda .■ . .................................. .. 56 25. Ostracoda .............................. 57 26. Vertebrata ..................................... .............................. ... ................... 58 27. GEOLOGIC MAP OF THE STUDY AREA NORTH OF ASHFORK, ARIZONA ........................................... ... Back Pocket ABSTRACT The Toroweap Formation in the area north of Ashfork, Arizona, is in an area of transition from predominantly "normal marine" de position in the Aubrey Cliffs area to the west to predominantly non marine deposition to the east of Sycamore Canyon to the southeast. The Toroweap in the study area is divisible into nine units, each repre senting a different environmental setting. These changes in environ ments of deposition are best explained by climatic fluctuations in the source area, affecting both the amount of sediment and fresh water contributed to the sea. The main factors controlling deposition in the study area are the position of the brackish-saline water interface, turbidity, and energy. Heavy minerals and clays show that the predominant sources for units I through VIII and unit IX are probably different. Units I through VIII contain rounded, super-mature heavy minerals and illite; while unit IX contains angular sub-mature heavy minerals and mont- m o rillonit e - ve rm ic ulit e. The chief factors affecting the faunal distribution in the study area are substrate, water depth, energy, turbidity, and salinity. The most important of these seems to be the character of the substrate. ix The Toroweap Formation in the area north of Ashfork is characterized by very nearshore, shallow-water fauna that lived near a desert coastline under conditions of climatically controlled alter nating brackish and saline water environments. INTRODUCTION Purpose and Scope of Investigation The Toroweap Formation cropping out north of Ashfork, Arizona, is in an area of transition from predominantly "normal marine" deposi tion in the Aubrey Cliffs area to the west (McKee, 1938; Belden, 1954) to predominantly non-marine deposition to the east of Sycamore Canyon to the southeast (McKee, 1938). The Toroweap Formation in the Ash fork area seemed promising