Geochronology of older Precambrian rocks in Gila County, Arizona Item Type text; Dissertation-Reproduction (electronic); maps Authors Livingston, Donald Everett 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 11/10/2021 03:30:17 Link to Item http://hdl.handle.net/10150/565197 GEOCHRONOLOGY OF OLDER PRECAMBRIAN ROCKS IN GILA COUNTY, ARIZONA by Donald Everett Livingston A Dissertation Submitted to the Faculty of the DEPARTMENT OF GEOLOGY In Partial Fulfillment of the Requirements For the Degree of DOCTOR OF PHILOSOPHY In the Graduate College THE UNIVERSITY OF ARIZONA 1 9 6 9 THE UNIVERSITY OF ARIZONA GRADUATE COLLEGE I hereby recommend that this dissertation prepared under my direction by Donald Everett Livingston________________ entitled Geonhrnnol ogv of Older Prenamhrlan Rooks In Gila County, Arizona_________________________ be accepted as fulfilling the dissertation requirement of the degree of Doctor of Philosophy________________________ Paul E, Damon________ 0 V^ ^ \ A ^ ^ \ Dissertation Director Date ' After inspection of the final copy of the dissertation, the following members of the Final Examination Committee concur in its approval and recommend its acceptance:* This approval and acceptance is contingent on the candidate's adequate performance and defense of this dissertation at the final oral examination. The inclusion of this sheet bound into the library copy of the dissertation is evidence of satisfactory performance at the final examination. 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 allow­ able without special permission, provided that accurate acknowledgment of source is made. Requests for permission for extended quotation from or reproduction of this manu­ script 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: y ACKNOWLEDGMENTS There are many who have aided me in this study, directly and indirectly, professionally and in friend­ ship. I was most fortunate to be able to discuss many matters with the late Dr. E. D. Wilson of the Arizona Bureau of Mines. His vast experience and keen insight greatly aided the early formulation of this study. My greatest thanks are to Dr. Paul E. Damon of the Depart­ ments of Geochronology and Geology of the School of Earth Sciences at The University of Arizona. It is through him that funds for this study were made available from the National Science Foundation Grant No. GA-856. He has guided me surely and steadily through the trials and frustrations of constructing laboratory facilities and instrumentation and provided continuous encouragement. I thank; Dr. E. J. McCullough (Department of Geology, University of Arizona) for the loan of a field vehicle; Dr. J. R. Sturgul (Department of Geology, Uni­ versity of Arizona) for introducing me to the secrets of computer programming; Dr. A. F. Shride (U, S. Geological Survey) for first calling my attention to the White Ledges; Dr. H. W. Pierce (Arizona Bureau of Mines) for taking me into the field for several days and for much encouragement. iii iv I owe many thanks to Dr. R. L. Manger, Dr. R. C. Erickson, Mr. R, L. Eastwood and other members (both past and present) of this laboratory for chemical and isotopic analyses and stimulating discussions concerning both geological and analytical problems. C. E. Hedge, S, S. Goldich and F. G. Walthall introduced me to the problems and complexities of Rb-Sr dating at the Isotope Geology Laboratory of the U. S. Geological Survey in Washington, D. C. Drs. E. B . Mayo, S. R. Titley, E. J. McCullough, B. E. Nordlie and P. E. Damon all have read the manuscript and provided courteous and helpful criticism, though I alone retain the respon­ sibility for its shortcomings. I especially thank my wife Anne for her aid, encouragement and forebearance. TABLE OF CONTENTS Page LIST OF T A B L E S ....................................... viii LIST OF ILLUSTRATIONS.............................. X ABSTRACT .................................. xii Chapter 1. INTRODUCTION................................ 1 Purpose Methods of Study .................. Geological Methods of Study . Isotopic Methods of Study . <yt U > K > The Conceptual Use of Time Scales in Geological Science .............. 8 The Theory of Isotopic Dating .............. 13 The K-Ar Method of Age Determination . 17 The Rb-Sr Method of Age Determination . 22 The Geochemistry of Rb/Sr Ratios ..... 26 The General Character of Older Precambrian Rocks in Central Arizona.................... 28 Reviews of Previous W o r k .................... 33 Geological Review ...................... 34 Isotopic Review ........................ 39 Older Precambrian Orogenies ............ 41 The Mazatzal Orogeny ................ 43 The Arizonan Orogeny.......... 44 Summary of Previous W o r k ................ 46 2. EXPERIMENTAL METHODS OF INVESTIGATIONS .... 48 Physical Preparation of Samples ............ 49 Total Rock Samples...................... 50 Mineral Separation and Purification . 51 Fine G r i n d i n g .......................... 55 Potassium and Argon Analyses ................ 55 Potassium Analyses ...................... 56 Argon Analyses.......................... 56 v vi TABLE OF CONTENTS (Continued) Chapter Page X-Ray Fluorescence Analysis for Rubidium and Strontium ........................ .. 58 Operating Conditions ............. 60 Elemental Analysis . ................... 62 Element Ratio Analysis .................. 72 Chemical Preparation of Samples ............ 73 Chemical Digestions .................... 73 Chemical Separations.......... 74 Distribution Coefficients of Selected Elements on Cation Exchange Resin .......... 77 Mass Spectrometer Analyses .................. 90 The Solid Source Mass Spectrometer . ♦ . 91 The Vacuum System ........ 91 The Ion Source ....................... 92 The Magnetic Analyser .............. 95 The Ion Collector, Amplifier and Recorder......................... 95 Ancilliary Equipment ................ 96 Isotope Dilution for Rubidium and S t r o n t i u m ........................... 96 Principles of Isotope-dilution Analysis......................... 97 Calibration of Spike Solutions .... 99 Isotope Dilution Measurements .... 99 Isotope Ratio Analysis of Strontium . 102 Principles....................... 108 T e c h n i q u e ....................... 108 Electrical Calibration .............. 110 Empirical Calibration .............. Ill Data Collection and R e d u c t i o n ........... 118 X-ray D a t a ........................... 118 Isotope Dilution D a t a ............... 119 Strontium Isotope Ratio Data ............ 120 Isochron Analyses ............ ..... 120 Experimental Conclusions .................... 122 3. THE WHITE LEDGES AND BLACKJACK MOUNTAINS . 126 Location and Access ......................... 126 Geology ..................................... 127 The Redmond F o r m a t i o n .............. 130 The Hess Canyon G r o u p ............ 138 The White Ledges Formation ........ 140 The Yankee Joe Formation........ 147 The Blackjack Formation ............ 151 vii TABLE OF CONTENTS (Continued) Chapter Page The Ruin Granite........................ 153 D i a b a s e ................................ 155 Structure 156 Relations to Younger Rocks .............. 162 The Apache G r o u p .................... 162 Middle Tertiary Rocks .............. 165 Regional Correlation .................... 165 Lateral Thickness Variation ............ 166 Isotope Geochronology.................. .. 166 Dating of the Redmond Formation ........ 169 Dating of the Ruin Granite.............. 171 4. GEOLOGICAL INVESTIGATIONS IN OTHER AREAS . 180 The Pinal M o u n t a i n s ........................ 180 Geology of the Pinal Mountains .......... 181 Dating in the Pinal M o u n t a i n s .......... 183 The Tortilla Mountains ...................... 191 Geology of the Tortilla Mountains .... 191 Isotope Geochronology .................. 193 The Southern Mazatzal M o u n t a i n s ........ .. 196 Geology of the Southern Mazatzal M o u n t a i n s .................... 196 Isotope Geochronology .................. 197 Initial Strontium Isotope Ratios and Maximum A g e s ................................ 201 5. SUMMARY OF RESULTS AND CONCLUSIONS ........... 205 APPENDIX 1. STATEMENTS DEFINING THE MAZATZAL OROGENY .............................. 208 APPENDIX 2. LOCATIONS AND DESCRIPTIONS OF DATED SAMPLES .............................. 213 LIST OF REFERENCES 217 LIST OF TABLES Table Page 1. The Five Most Useful Long-lived Radio­ active Decay Schemes..................... 15 2. Isotopic Abundances of Potassium, Calcium and A r g o n ............................... 18 3. Isotopic Abundances of Rubidium and S t r o n t i u m ............................... 24 4. Properties of Alkali and Alkaline Earth M e t a l s .............. 27 5. Chemical Variation in Igneous Rocks (ppm) .....................................