The clay mineralogy of selected fault gouges Item Type text; Thesis-Reproduction (electronic) Authors Bladh, Kenneth Walter 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 01:00:44 Link to Item http://hdl.handle.net/10150/554458 THE CLAY MINERALOGY OF SELECTED FAULT GOUGES by Kenneth Walter Bladh 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 3 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 interest of scholar­ ship. In all other instances, however, permission must be obtained from the author. SIGNED: APPROVAL BY THESIS DIRECTOR This thesis has been approved on the date shown below: wa / 7 /f 7. fOHN W. ANTHONY?V J Datb Professor of Geosciences ACKNOWLEDGMENTS I thank Dr. John W. Anthony for suggesting the top ic, for in­ valuable discussions, and for guidance during the study. Drs. Spencer R. Titley and Joseph F. Schreiber, Jr. critically read the manuscript and offered useful suggestions. I thank Dr. Ralph W. G. Wyckoff for the use of X-ray diffraction and spectrographic analysis equipment and the general use of the resources of his laboratory „ M essrs. John T. Eastlick and David Johnson, geologists for the Inspiration Consolidated Copper Company, Inspiration, Arizona, are thanked for assistance in collecting samples. The Inspiration Consoli­ dated Copper Company is acknowledge for allowing the use of material collected on their property. Financial support from Training Grant 5 T01 DE 00126 of the National Institute of Dental Research, National Institutes of Health, is also acknowledged. I thank my wife, Kathi, for suggestions, typing skills, and tolerance during the preparation of this manuscript. iii TABLE OF CONTENTS Page LIST OF TABLES . ........................................................................ vi LIST OF ILLUSTRATIONS.................................................................... vii ABSTRACT............................................................................................................. v iii INTRODUCTION................................................................................................ 1 GEOLOGY OF THE MIAMI-INSPIRATION PROPERTY................................ 4 NOMENCLATURE................................................................................................ 9 Faults and Cataclastic R ocks ........................................................... 9 Clay Minerals ........................................................................................... 10 METHOD OF S T U D Y ....................................................................................... 13 Separation of Clay-size Fraction ....................................................... 13 Preparation for X-ray Diffraction A nalysis ..................................... 18 X-ray Diffraction Identification of Clay M inerals ....................... 19 Identification of the Non-clay Mineral F raction ...................... 25 LITHOLOGY OF THE MIAMI FAULT CATAC LAS TICS................................ 29 LITHOLOGY OF THE NO. 5 FAULT CATACLASTICS ................................ 32 MINERALOGY OF MIAMI FAULT CATACLASTICS..................................... 34 Clay Minerals ...................................................... 34 Non-clay Minerals .................................................................................. 40 MINERALOGY OF NO. 5 FAULT CATACLASTICS ..................................... 41 Clay Minerals ........................................................................................... 41 Non-clay Minerals .................................................................................. 46 SPECTROGRAPHIC EXAMINATION OF CLAY-SIZE MATERIAL .... 48 Analytical Technique .............................................................................. 4 8 Results ..................................................................................................... 49 I r o n .................................................................................................... 49 M agn esiu m ....................................................................................... 52 M a n g a n e se ....................................................................................... 52 iv V TABLE OF CONTENTS—Continued Page Calcium „ „ . „ ................. 52 Sodium and Phosphorus 52 Copper ...................... 53 Other Elements .................. 53 Applicability to Mineral Identification .......... 53 DISCUSSION ........ ... .... 56 No. 5 Fault ...................... 56 Miami Fault ...................... 59 CONCLUSIONS ...................... 63 REFERENCES. ....................... 67 LIST OF TABLES Table Page I. A Classification of the Clay Minerals 12 2 „ Summary of the X-ray Characteristics of Clay Minerals . 26. 3„ D-spacings in Angstroms from Oriented Slides (Clay- size Fraction) from Miami Fault Cataclasties ...... 35 4. Mineral Distribution along the Miami Fault ....... 38 5. D-spacings in Angstroms from Oriented Slides (Clay- size Fraction) from No. 5 Fault Cataclastics ..... 42 6. Comparison of D-spacings of a Biotite Phenocryst from the Dacite Hanging Wall of the No. 5 Fault with Published Data for Biotite and Illite . ...... 44 7. Elemental Analyses of Gouge Samples and Standards (Clay-size Fraction unless Otherwise Noted) ..... 50 8. Comparison of Elemental Analyses of API Reference. Clay Minerals .................. 51 v i LIST OF ILLUSTRATIONS Figure Page \ 1 „ Location of Drill Holes across the Miami Fault and Surface Exposure of the No. 5 Fault (Map View) . 2 2 . Location of Sample Levels and Lithologies along the Miami Fault ................. 5 3. Geologic Section of the Inspiration Property, Arizona. 7 4 . Flow Diagram of the Analytical Procedure ........ 17 5 . Relative Concentrations of Clay Minerals along the Miami Fault ................. 39 6. Diagrammatic Representation of the Mineral Distribution across the No. 5 Fault ......... 43 v ii ABSTRACT The clay mineralogy of gouge from two postmineralization nor- maTfaults associated with a porphyry copper deposit was determined by conventional X-ray diffraction techniques„ The No. 5 and Miami fault gouges from the Inspiration Consolidated Copper Company property at Globe, Arizona, are almost identical mineralogically to the contiguous wall rocks. Most of the gouge contains angular to subrounded fragments of quartz and wall rock in sericitic matrix„ Kaolinite, muscovite, and smectite occur in varying relative abundances on the depths sampled across the Miami fault. The No. 5 fault gouge contains a larger suite of clay minerals than does the Miami fault, gypsum precipitated from ground waters, and genetically unexplained palygorskite. The faulting process created a nonequilibrated mixture’ of wall- derived clay minerals. No minerals were formed by the faulting process. Generally, wall-rock type mineralogy decreases in abundance away from the source wall, stopping short of the opposite wall. The effects of sol­ utions traveling along the gouge zone are controlled by the local physico­ chemical environments. Chemically resistant minerals occur farther from the source wall than do easily leached minerals. Shearing is most in­ tense near walls or with depth, and the mechanically least resistant wall contributes the most material to the gouge . INTRODUCTION The clay minerals literature, although extensive, does not in­ clude an adequate treatment of clay mineral occurrences in fault gouge„ The object of this study is to collect, examine, and describe the min­ eralogy of gouge material associated with faulting in rock. Because of the lack of previous work in this area, the direction of this study de­ veloped and changed during the investigation. However, the goals re­ main to describe the minerals present in the fault gouge and, if possible, explain their origin. Initially, a large number of faults were sought with the.inten­ tion of collecting gouge samples from each. Unfortunately, common as gouge seems to be, material suitable for study is rare. A relatively wide gouge zone (on the order of a few feet across) is required and should be nonlithified and unaffected by postfaulting solutions. Because the me­ chanical effects of faulting upon the mineralogy were of primary interest, gouge significantly altered by solutions and extensive surface weather­ ing was avoided. Faults recently exposed in open pit mining operations were examined for gouge of desired quality. After a number of unsuccessful examinations of faults, workable gouge material was collected across