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By Verl Leon Smith a Thesis Submitted to the Faculty of Th Hypogene alteration at the Esperanza Mine, Pima County, Arizona Item Type text; Thesis-Reproduction (electronic) Authors Smith, Verl Leon, 1943- 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 04/10/2021 11:08:00 Link to Item http://hdl.handle.net/10150/566585 HYPOGENE ALTERATION AT THE ESPERANZA MINE, PIMA COUNTY, ARIZONA "by Verl Leon Smith 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 5 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. APPROVAL BY THESIS DIRECTOR This thesis has been approved on the date shown below: Zf /?7j Date ACKNOWLEDGMENTS I wish to express appreciation to my thesis director, J . M . Guilhert, and other members of my committee and the faculty, especially D. E. Livingston, S. R. Titley, D. L. Norton, T. S. Lovering, T. M. Teska, and W. J. McLean for their guidance and assistance during my studies at The University of Arizona. I also wish to thank the many graduate students who have provided encouragement and assistance. I wish to thank the Duval Corporation for permission to undertake this study and for access to their property. Special thanks also to Duval geologists, C.D. lies and C. A. Oakley, for assistance during the initial phases of this project. I am especially grateful to the National Science Foundation for support, in the form of a graduate fellowship, which made this study and my graduate education possible. And thanks to Sandra for encouragement and patience. iii TABIfi OF CONTENTS Page LIST OF ILLUSTRATIONS....................................... vii LIST OF T A B I E S ................ x ABSTRACT ................................................... xi 1. INTRODUCTION ............................................. .. 1 M e t h o d s .......... ....................................... 1 Location and Setting ............................. 2 H i s t o r y .......... ................................ .. 4 Previous W o r k ........................................... ^ General Geologic S e t t i n g .............. ................ 5 Structural Setting ............ .. ..................... 6 2. PETROGRAPHY............................... ............. 8 Ox Frame V o l c a n i c s .......... 9 Volcanic Breccia ................................... 9 Quartzite........................................... 12 Rhyolite Tuff B r e c c i a ............ 12 Rhyolite Welded Tuff ............................. 15 Rhyolite and Quartz Latite Crystal Tuff . ........... 15 Leucodacite............................ 17 Biotite Quartz Diorite Porphyry.......... '............. 18 Biotite-Horhblende Andesite . ....................... 23 Rhyodacite Porphyry .......................... 25 Leuco-Quartz Diorite Porphyry .............. 31 Dacite Porphyry.................... 32 Quartz Monzonite Porphyry.................. 37 Miscellaneous Rock T y p e s .............. 48 Alaskite ........ ............ ....... 48 Rhyolite Porphyry ..... ......................... 50 A p l i t e ............................................. 51 3. ALTERATION PETROGRAPHY ............ 54 Pervasive Alteration ................................... j)4 Ox Frame Volcanics . ................ ..... ^4 Biotite Quartz Diorite Porphyry ..................... 57 Rhyodacite Porphyry . ............................... 58 Leuco-Quartz Diorite Porphyry ....................... 60 Quartz Monzonite Porphyry ........................... 60 iv V T A M E OF CONTENTS —Continued Page Orthoclase Metasomatite . ........................... 63 Veinlets and Veinlet Controlled Alteration ....... 69 Orthoclase Veinlets ..... ....................... 69 Orthoclase Veinlets in Biotite Quartz Diorite P o r p h y r y .............. ........................ 70 Orthoclase Veinlets in Quartz Monzonite Porphyry 7^ Orthoclase Veinlets in Other Rock T y p e s ........ 75 Alhite Veinlets.................. .............. .. • 75 AlMte Veinlets in Biotite Quartz Diorite P o r p h y r y ................ .......... ............ 75 Alhite Veinlets in Quartz Monzonite Porphyry . 76 Leuco-Quartz D i o r i t e ........................... 77 Quartz-Molybdenite Veinlets ......................... 77 Quartz-Pyrite-Sericite Veinlets . ............. 77 Sericite-C hlorite-Sulfide V e i n l e t s ............ 79 Gypsum Veinlets.................. .................. 81 Supergene Effects ....................................... 82 Fluid Inclusions .......... ....... 82 Summary of Alteration ........ ....... .......... 83 Veinlet D i s t r i b u t i o n ............................... 86 Correlation of Alteration and Mineralization .... 88 Correlation of Mineralization and Rock T y p e ........ 91 4. CHEMICAL DATA ............................................... 92 Major Element Variation ................................. 92 Ca-K-Na Plots ....................................... 97 ACF-AKF P l o t s .........................'.............. 97 Normative Qz-Or-Pl Plots ....................... 105 Minor Elements . ............................. 107 Microprote Data ............................... Ill 5. X-RAY D A T A ..................................... 118 Muscovite Polymorphs .................................... 118 Structural State of Potassium Feldspars . ............... 118 Composition of Potassium F e l d s p a r s ..................... 120 6. INTERPRETATIONS OF THE ALTERATION-MINERALIZATION SYSTEM AT E S P E R A N Z A .................... 122 Backgroundt The Proposed Models ....................... 122 The Ortho-Magmatic M o d e l ........................... 123 The Circulating Meteoric Fluid Model ........ 123 Combination of Models ..... ..................... 124 Vi TABLE OF CONTENTS— Continued Page Interpretation of Alteration Assemblages ............... 124 Biotitization and Orthoclase-Ghlorite Alteration in the Biotite Quartz D i o r i t e ....................... 124 Orthoclase-C hlorite Alteration in the Leucocratic R o c k s ....................................... 131 Altite and Alhite Veining ........................... 132 Final Stages of the Alteration S y s t e m .............. 133 Rock Type Control on Alteration-Mineralization . 135 Zoning of Alteration ............................... 139 Summary of the Alteration S y s t e m ....................... 140 Suggestions for Further Work ......... ........ 142 APPENDIX A: RESULTS OF CHEMICAL ANALYSES ................... 144 APPENDIX Bj X-RAY FLUORESCENCE ANALYTICAL AND DATA REDUCTION TECHNIQUES........................... 150 REFERENCES ................................................. 155 LIST OF ILLUSTRATIONS Figure Page 1. Index map showing location of Esperanza and Sierrita Mines . ......................................... 3 2. Generalized rock distribution map, Esperanza Mine .... 10 3* Sample location map, Esperanza Mine ...... ........ 11 4. Modal Qz-Or-Pl for Ox Frame Volcanics .................. 14 5 . Texture of rhyolite welded tuff ......................... 16 6. Texture of rhyolite crystal tuff ......................... 16 7 . Modal Qz-Or-Pl for biotite quartz diorite .............. 21 8. Biotite cluster with relict hornblende in biotite quartz diorite .................. ....... ........ 22 9. Texture of hornblende a n desite......................... ,, 24 ■> 10. Rapakivi feldspar megacryst in rhyodacite porphyry .... ; 26 11. Modal Qz-Or-Pl for rhyodacite porphyry . ................ 29 12. Texture of rhyodacite p o rphyry........................... 30 13* Detail of rapakivi feldspar in rhyodacite porphyry .... 30 14. Modal Qz-Or-Pl for leuco-quartz diorite porphyry ........ 34 15• Texture of leuco-quartz diorite porphyry ................ 35 16. Matrix of leuco-quartz diorite porphyry ................ 36 17 • Matrix of leuco-quartz diorite porphyry within orthoclase veinlet envelope ................ ...... 36 18. Dacite porphyry matrix ................................. .. 38 19* Texture of "western" quartz monzonite po rphyry.......... 44 20. Plumose granophyre ........................................ 44 vii viii U S T £F ILLUSTRATIONS —Continued Figure Page 21. Texture of "eastern” quartz monzonite porphyry.......... 46 22. Detail of rapaJcivi feldspar in quartz monzonite p o rphyry................................................. 4? 23• Modal Qz-Or-Pl for quartz monzonite porphyry........... 49 24. Diagrammatic veinlet relations........... 55 25* Schematic paragenesis of alteration and veinlet minerals................................. ................ 56 26. Irregular biotite clots in biotite quartz diorite
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