1 POST-MINERAL NORMAL FAULTING IN ARIZONA PORPHYRY SYSTEMS By Phillip A. Nickerson _________________ A Dissertation Submitted to the Faculty of the DEPARTMENT OF GEOSCIENCES In Partial Fulfillment of the Requirements For the Degree of DOCTOR OF PHILOSOPHY In the Graduate College THE UNIVERSITY OF ARIZONA 2012 2 THE UNIVERSITY OF ARIZONA GRADUATE COLLEGE As members of the Dissertation Committee, we certify that we have read the dissertation prepared by Phillip A. Nickerson entitled Post-Mineral Normal Faulting in Arizona Porphyry Systems and recommend that it be accepted as fulfilling the dissertation requirement for the Degree of Doctor of Philosophy _______________________________________________________________________ Date: 04/30/2012 Eric Seedorff _______________________________________________________________________ Date: 04/30/2012 Mark Barton _______________________________________________________________________ Date: 04/30/2012 George Davis _______________________________________________________________________ Date: 04/30/2012 Peter Reiners _______________________________________________________________________ Date: 04/30/2012 Charles Ferguson Final approval and acceptance of this dissertation is contingent upon the candidate’s submission of the final copies of the dissertation to the Graduate College. I hereby certify that I have read this dissertation prepared under my direction and recommend that it be accepted as fulfilling the dissertation requirement. ________________________________________________ Date: 04/30/2012 Dissertation Director: Eric Seedorff 3 STATEMENT BY AUTHOR This dissertation 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 dissertation 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 or her 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: Phillip A. Nickerson 4 ACKNOWLEDGEMENTS I would like to thank my major advisors, Eric Seedorff and Mark Barton for their guidance, assistance, and patience. I also greatly appreciate valuable feedback from my committee members, George Davis, Peter Reiners, and Charles Ferguson. I’d like to recognize my many geologic predecessors--in particular the contributions from the USGS, AZGS, and other graduates students who generated an invaluable archive of geologic maps heavily utilized in this study. Without this high-quality geologic framework, this work would not have been possible. Financial support for this project came from the Sciences Foundation Arizona, Lowell Institute for Mineral Resources, Eurasian Minerals, and the Society of Economic Geology Hugh E. McKinstry Student Reasearch Fund. Logistical support including drill- hole information, helicopter access, and some regional data compilation was provided by Bronco Creek Exploration. 5 DEDICATION To my wife Laura, and my family. 6 TABLE OF CONTENTS LIST OF FIGURES .............................................................................................. 12 ABSTRACT .......................................................................................................... 13 INTRODUCTION ................................................................................................ 15 Laramide porphyry systems in the Basin and Range province ......................... 15 Extension in the Basin and Range province ................................................. 17 Regional geologic framework ........................................................................... 19 PRESENT STUDY ............................................................................................... 23 Methodology ..................................................................................................... 23 Key results ........................................................................................................ 24 Appendix A: “Domino-style” tilting in metamorphic core complexes: Evidence from radial dikes in the Pinaleño Mountains, Arizona ................. 24 Appendix B: Sodic-(calcic) alteration in two Arizona porphyry copper systems: Hybrid hydrothermal systems of Laramide and mid-Tertiary ages 25 Appendix C: Dismembered porphyry systems near Wickenburg, Arizona: District-scale reconstruction with an arc-scale context ................................ 27 FIGURE CAPTIONS............................................................................................ 29 REFERENCES ..................................................................................................... 32 7 APPPENDIX A: “DOMINO-STYLE” TILTING IN METAMORPHIC CORE COMPLEXES: EVIDENCE FROM RADIAL DIKES IN THE PINALEÑO MOUNTAINS, ARIZONA .................................................................................. 49 Abstract ................................................................................................................. 50 Introduction ........................................................................................................... 51 Pinaleño MCC ....................................................................................................... 52 Porphyry Dike Swarm..................................................................................... 53 Dike Orientations and Their Use as a Paleo-Vertical Indicator ...................... 54 Folding of footwall rocks ................................................................................ 56 Hydrothermal Alteration ................................................................................. 56 Interpretation of Oligocene Regional Stress Patterns in Southeastern Arizona ... 56 Implications for the formation of the Pinaleño MCC ........................................... 58 Discussion ............................................................................................................. 60 Conclusions ........................................................................................................... 61 Acknowledgments................................................................................................. 62 References ............................................................................................................. 62 Appendix A.1 ........................................................................................................ 79 References ............................................................................................................. 81 8 APPENDIX B: SODIC-(CALCIC) ALTERATION IN TWO ARIZONA PORPHYRY COPPER SYSTEMS: HYBRID HYDROTHERMAL SYSTEMS OF LARAMIDE AND MID-TERTIARY AGES ............................................... 88 Abstract ................................................................................................................. 89 Introduction ........................................................................................................... 90 Geologic Setting.................................................................................................... 92 Geochronology ...................................................................................................... 95 Tea Cup system ............................................................................................. 96 Eagle Pass system ......................................................................................... 97 Hydrothermal alteration assemblages ................................................................... 97 Tea Cup system ................................................................................................. 98 Eagle Pass system ........................................................................................... 100 Compositions of hydrothermal minerals ............................................................. 102 Tea Cup system ............................................................................................... 102 Eagle Pass system ........................................................................................... 103 Gains and losses in sodic alteration ............................................................... 104 Comparison of sodic (-calcic) and greisen hydrothermal alteration assemblages at Tea Cup and Eagle Pass with other localities ..................................................... 104 Origin of sodic (-calcic) and iron oxide-rich alteration ...................................... 107 9 Source of fluids ............................................................................................... 107 Relationship of sodic-(calcic) alteration to iron oxide-rich alteration ............ 110 Discussion ........................................................................................................... 111 Hybrid hydrothermal systems ......................................................................... 111 Implications for exploration ............................................................................ 115 Summary and Conclusions ................................................................................. 117 Acknowledgments..............................................................................................