Isotopic and geochemical characteristics of Laramide igneous rocks in Arizona. Item Type text; Dissertation-Reproduction (electronic) Authors Lang, James Robert. 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 05/10/2021 20:48:42 Link to Item http://hdl.handle.net/10150/185600 INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer. The quality of this reproduction is dependent upon the quality of the copy submitted. 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Ann Arbor, MI 48106 ISOTOPIC AND GEOCHEMICAL CHARACTERISTICS OF LARAMIDE IGNEOUS ROCKS IN ARIZONA by J ames Robert Lang 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 1991 2 THE UNIVERSITY OF ARIZONA GRADUATE COLLEGE As members of the Final Examination Committee, we certify that we have read the dissertation prepared by ~J~a~m~e~s~R~o~b~e~r~t~L~a=n~g~ __________________________ entitled ISOTOPIC AND GEOCHEMICAL C~CTERISTICS OF LARAMIDE IGNEOUS ROCKS IN ARIZONA and recommend that it be accepted as fulfilling the dissertation requirement for the Degree of Doctor of Philosophy P /.#_ 7/23/91 ~:~·;(·~4 Date 7/23/91 Mark • Barton Date Ei.Mc~A.~ 7/23/91 Eleanour A. Snow Date Date Date Final approval and acceptance of this dissertation is contingent upon the candidate's submission of the final copy 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. 7/23/91 ncer R. Titley Date 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 fl'om 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 oblamed from the aUlhor. ~ Lf4f ~ SIGNED: ~ c;- d 4 TABLE OF CONTENTS LIST OF ILLUSTRATIONS ....•.•..•••••.•...••.•.••••••••••••••..••••.••••• 7 LIST OF TABLES . • . • . • • • • . • • . • . • . • • • • • • • • • • • • . • • • • • • • • • . • . • . .• 9 ABSTRACf . • . • • . • . • • • • • • • • • • . • . • . • • . • . • . • • • • • • • • • • . • • • • . • • • • . • • . .. 10 CHAFfER 1: INTRODUCTION ....•.•.••.••••••.••••.•••••••.••...••••...•. 11 CHAFfER 2: GENERAL GEOLOGY . • . • . • • • • • • • • • • • • • • . • • • • • • • • • • . • . • .. 16 Regional Geolo!tic Setting •.•.••••••..••...•••..••••..•••..•..•••••.•.. 16 Crustal Provinces in Arizona •.....•.•.•..•...••••.•..••••......••..•... 18 Criteria for Selecting Igneous Systems for Study •...•••••.••••.....•...•..... 21 Definitions of Productive and Barren Intrusions •..•••.•••••••.•.•.......••.. 22 Timing and Duration of Laramide Magmatism ....•.•.•••••••.••........•... 27 A Generalized Description of Laramide Igneous Systems • . • • . • • • • . • • . • . • • .. 27 Descriptions of Individual Igneous Systems •...••.... • . • . • • • • • . • . • • • • . • . .• 29 Ray District ..••.•.....•••.•.••••..••••••.••••.•••.......••.• 29 Christmas District .•.•.•••••.•••••••••••.•••••••••.•.•..••..•.• 31 Copper Creek District .•.•.•••••••.••.••••.•••••••••..••••.•••.. 33 Safford District .• • • • • . • • • • • • • . • • . • • • • • • • . • • • • . • . • • • . • • • • • .• 3S Crown King Stock .•••.••••••••••••• • • • • • • • • • • • • • • • • . • . • . • .• 36 Copper Basin District ..••••.•.••.•••••••••••••••••••..••...•.•. 37 Diamond Joe Stock ...•••.•.•.••••••••••.•.••••••••.•••....•... 37 Bagdad District •...••..•.•••••.•.......••••..•.•...•.•••.•.•.. 39 Tombstone District .••...•.•••....•..•..•.•..•••..•..•....•.•.. 42 Sierrita District ...•...•...••••••••..••.••....•••........••.... 43 Santa Rita Mountains Suite .....•.•....••••••...•..•............. 43 CHAFfER 3: PETROGRAPHY, PETROLOGY, AND ANALYTICAL RESULTS . .. 45 Petrography • . • . • • . • . • . • • . • • . • . • • • . • . • • • . • • • . • . • • . • . .. 4S Major Element Geochemistry . • . • . • . • • . • . • . • • • . • • • • • • • • • • . • • . .. 51 Rare Earth Element Geochemistry . • . • • . • . • . • . • . .• 58 A Generalized Pattern of Behavior. • • . • . • • • . • • . .. 58 REE Behavior in Individual Igneous Systems .....................••.• 62 Sm-Nd and Rb-Sr Isotope Geochemistry . • . • . • • . • . .. 69 Representation of Isotopic Data • . • . • . • . • . • . • . .. 69 Results of Sm-Nd and Rb-Sr Isotope Analyses ......••.•.............. 71 Isotopic Character of Arizona Crustal Provinces ....••••.............. 79 Trace and Minor Element Geochemistry. • . • . .. 79 5 CHAPTER 4: PRODUCI1VE VERSUS BARREN IGNEOUS ROCKS ......•.....••.. 94 Major Element Behavior ...•....•.....•.........•...•........... :..... 94 Trace Element Behavior . .. 96 Rare Earth Element Behavior .....•...........•..............•......... 96 Oxidation State ....••.....•...•....•.........••....•.........•..... 100 Nd and Sr Isotope Behavior ..•..••. • . • . .. 100 CHAPTER 5: DISCUSSION . • . • . • • . • • . .. 104 Introduction . • . • • • • . • • . • • • . • • • • . .. 104 Isotopic Evidence for Components of Laramide Magmas • . • • . • . .. 105 Nature of the Lower Crust of Arizona .••....•....•...........•.... 105 Isotopic Reservoirs That Contributed to Laramide Magmas ............. 108 Geographic Variations in the Isotopic Composition of Laramide Magmas. ................... 112 Crust-Mantle Mixing ....•..•..••...............•........ • . .. 113 Different Types of Mantle Contribution ............................ 113 Different Formation Ages of Crustal Provinces . • . • • .. 115 Different Isotopic Ages of Crustal Provinces . • . • . • . .. 115 Geochemically Distinct Provinces . • • • • • . .. 116 Different Petrogenetic Processes ....•••.........•..•...•......... 116 The Nd-Sr Isotopic Array. • . • • . • . • . • . • . • . • • . • . .. 117 Decoupling of Sr and Eu Behavior .•..•.....•....•.....•................ 120 Rare Earth Element Behavior .........................•............... 123 The Effects of Fluid Loss. ...................................... 123 Fractional Crystallization Effects ................................. 123 Partial Melting Effects . .. 130 Synthesis ...........•.•.......••..••..•........................... 133 Introduction ...••............•...••......•.•................ 131 Processes Affecting Laramide Magmagenesis .....•........•......... 132 Mechanisms For Producing the Observed Geochemical Behavior ......... 136 Implication of the Models for Metallogenesis .......•................ 141 Laramide Metallogenesis .. • . .. 143 CHAPTER 6: CONCLUSIONS.............................................. 146 APPENDIX A: SAMPLE LOCATIONS ....................................... 148 APPENDIX B: COMPILATION OF RADIOMETRIC DATES ...................... 154 6 APPENDIX C: SAMPLE PREPARATION AND ANALYTICAL TECHNIQUES ••...... 159 Sample Collection and Preparation . • . • • . • . • . • . .. 159 Analytical Techniques for Isotopic Measurements ..••....................... 160 Analytical Techniques for Trace Element Analysis . • . .. 160 Whole Rock Analysis • . • . • . • . • . • . 160 APPENDIX D: ANALYTICAL RESULTS AND NORMATIVE AND MODAL MINERALOGy ....................•.•..........•....•............ 168 APPENDIX