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Geology of the Copper Occurrence at Copper Hill, Picuris Mountains, New Mexico

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Geology of the Copper Occurrence at Copper Hill, Picuris Mountains, New Mexico Geology of the copper occurrence at Copper Hill, Picuris Mountains, New Mexico Item Type text; Thesis-Reproduction (electronic); maps Authors Williams, Michael Lloyd 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 02/10/2021 12:08:51 Link to Item http://hdl.handle.net/10150/557925 GEOLOGY OF THE COPPER OCCURRENCE AT COPPER HILL, PICURIS MOUNTAINS, NEW MEXICO by Michael Lloyd Williams 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 19 8 2 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: John W. Anthony TT ✓ Dater Professor of Geosciences ACKNOWLEDGMENTS I would like to thank my advisory committee, Dr. J. W. Anthony, Dr. S. R. Titley, and Dr. J. M. Guilbert for their advice in this thesis . and also for their efforts and encouragement during my graduate studies at the University of Arizona. I am especially grateful for Dr. Anthonyf many contributions to my graduate program. I want to acknowledge the Anaconda Minerals Company for insti­ gating and generously funding this research. John King, Robert Johnson, and Ken Black have greatly contributed to the project and to my geologic ability in general. I am especially indebted to Robert Johnson for his help in the field and for his excellent advice during all stages of the project. His geologic contributions, as well as his friendship, will long be appreciated. Finally, I want to thank all the graduate students in the Depart ment of Geosciences who lent support and suggestions to this research, especially Sheila Seaman, John Zimmerman, Larry Segerstrom, Robert Smith and Lou Lepry. TABLE OF CONTENTS Page LIST OF ILLUSTRATIONS .................................. vi LIST OF TABLES ............ ix ABSTRACT * . ............. o » o , « x I. INTRODUCTION » 1 Methods of Study » o ' * .................... ..... » o 3 Field Research * .......... 3 Laboratory Research ........ » ............... 4 II o GENERAL GEOLOGY OF THE PICURIS MOUNTAINS ............... 5 Stratigraphy ............. 5 Structural Geology * * ....................... * . 8 Metamorphism................... .. ........... 9 Age Relationships ......................... 11 Tectonic Environment................... 13 III. THE GEOLOGY OF COPPER HILL . » e 14 Introduction................... - ................... 14 Stratigraphy „ . .............. 14 Oq^ Quartzite » » , » ....................... 14 0 q 2 Kyanite Quartz Eye Quartzite ............... 20 Oq^ Andalusite Quartzite » e ................. 26 Structural Geology .................................. 29 Quartz Veins ........................................ 36 Regional Characteristics of the Ortega Quartzite « • 40 IV o ECONOMIC GEOLOGY ............ 42 Introduction . « . » 42 Mining History of the Copper Hill District . o . 43 Styles of Economic Mineralization at Copper Hill o o o ................................ 44 Quartz Vein-hosted Mineralization ................. 44 X-ray and Electron Microprobe Analysis of Vein-hosted Minerals „ ............ „ . 55 Discussion: The Genesis of Vein-hosted Mineralization..................... 55 Grade and Reserves of Quartz Vein-hosted Mineralization „ ................ x......... 56 iv V TABLE OF CONTENTS— Continued Page Disseminated Mineralization in Ortega Quartzite on Copper Hill „ <, . „ . ................... 59 X-ray and Electron Microprobe Analysis of Disseminated Minerals ..................... 6 6 Distribution and Reserves of Disseminated Mineralization » <, ..................... 6 6 Grade of Disseminated Mineralization........... 67 Fracture-filling Copper Mineralization ............ 69 Discussion: Genesis of Fracture-filling Mineralization.............................. 69 Regional Extent of Mineralization in the Picuris Mountains » » o .................... 71 Constraints on the Age of Mineralization at Copper Hill .................................... 72 V, GENESIS OF THE COPPER HILL DEPOSIT » ................. 75 Introduction........................................ 75 Downward Mobilization ............................ 75 Discussion: Evidence against a Downward Mobilization Model . ................... 76 Strata-bound Models for Mineralization at Copper Hill . .............. 77 Comparison of Copper Hill with Known Strata- bound Copper Occurrences » « ............. 78 Epigenetic Mineralization..... ...................... 82 Evidence for Epigenetic Processes at Copper Hill , . ..................... « 82 Possible Sources of Epigenetic Mineralization at Copper H i l l .......... 87 Summary of Conclusions . ......................... 89 APPENDIX 1: CALCULATION OF THE VOLUME AND TONNAGE OF VEIN QUARTZ ON COPPER HILL ....... 90 APPENDIX 2: GEOCHEMICAL DATA ................... 92 REFERENCES............ 96 LIST OF ILLUSTRATIONS Figure Page lo Location Map of the Picuris Mountains and Copper Hill . 2 2 o Generalized Stratigraphic Succession in the Picuris Mountains . * . , . * . „ . „ . , . , 6 3o Precambrian Geology of the Picuris Mountains, Taos County 9 New Mexico „ ..o ... ........ in pocket 4. Map Showing the Picuris-Pecos Fault in Relation to the Picuris Mountains 9 Truchas Mountains 3 and Pecos Greenstone Belt ............. 10 5. Summary of the Deformationa!, MetamorphiCg and Magmatic Events in the Picuris Mountains ....... 12 6 . Geology of Copper Hill,- Picuris Mountains, Taos County, New Mexico ............ ......... in pocket 7. Cross-bedded Oq^ Ortega Quartzite ..... ............. 15 8 . Ortega Quartzite from Copper Ridge Showing Cross­ cutting Heavy Mineral-rich Bands.. ............. 18 9. Photomicrographs of Oq^ Quartzite Showing the Two Types of Heavy Mineral-rich B a n d s ................... 19 10. Photomicrographs of Oq^ Ortega Quartzite Showing Grains of Rutile and Ilmenite Outlining Quartz Grains .... 21 11. Photomicrographs of 0 q 2 Quartzite . .................... 22 . 12. Photomicrographs of Staurolite-bearing 0 q 2 Quartzite ( 0 < W .................................. 24 13. Photomicrographs of Iron-stained Kyanite Blades from Staurolite-bearing Quartzite ( O ^ A ^ ............. 25 14. Outcrops of Oqg Andalusite Quartzite ...................... 27 15. Hand Specimen of Oq^ Andalusite Quartzite ......... 28 16. Photomicrographs of Oqg Andalusite Quartzite ............. 30 vi vii LIST OF ILLUSTRATIONS--Continued Figure Page 17 - Dextral Fold in 0q~ Quartzite on the Southern Limb of the Copper Hill Anticline <, » «, ............... 31 18. Outcrop of Oqg Quartzite Showing an Antiformal F3 Fold ...................... 33 19. Outcrop of 0q3 Quartzite Showing Two Styles of Deformation ............. ............. 34 20. Rose Diagram Showing the Orientation of Fractures in Oq^ Quartzite .......... ... 35 21. Map of the Champion Adit Showing the Location of the Champion Vein ................. 37 22. Hand Sample of a Quartz Vein from Copper Ridge Showing Large Aggregates of Kyanite Blades (Bow Ties) ..................... 38 23. Vein Quartz Concordant with the Foliation of 0q3 Quartzite at the Southern End of the Champion Vein ........................ 39 24. Vug-filling Mineralization in the Champion Vein .... 46 25. Hand Specimens of Quartz Vein-hosted Mineralization . 47 26. Photomicrograph of Breccia-filling9 Vein-hosted Mineralization ................... 48 27. Photomicrographs of Brecciated Vein Quartz with Copper Mineralization . ........... ...... 49 28. Photomicrographs of Mineralization Replacing Kyanite Crystals in Vein Quartz .............. 51 29. Photomicrographs of Mineralization Replacing Silliman- ite in Vein; Quartz from Copper Hill . ........... 52 30. Photomicrograph of Vug-filling Mineralization in Vein Quartz from Copper Hill .............. 53 31. Photomicrographs of Radial and Concentric Textures in Vug-filling Mineralization ........... 54 viii LIST OF ILLUSTRATIONS— Continued Figure Page 32o Map Showing the Location of the Prospect Pit in Oq^ Quartzite Containing Quartzite-hosted, Dissemi­ nated Mineralization ....................... 60 33, Photomicrographs of Disseminated Mineralization in Oq^ Quartzite 61 34, Enlargement of Disseminated Mineralization Shown in Figure 33 ,,,,,,,,,,,,,, , ......... 62 35, Photomicrographs Showing Mineralization Replacing Kyanite Crystals in Oq^ Quartzite ................. 64 36, Photomicrographs Showing Copper and Iron Minerali­ zation Replacing Muscovite within Oq^ Quartzite , , 65 37, Hand Specimens Showing Fracture-controlled, Oxidized Copper Minerals in Vein Quartz
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