Lehigh University Lehigh Preserve Theses and Dissertations 1-1-1978 Gahnite-franklinite intergrowths at the Sterling Hill zinc deposit, Sussex County, New Jersey: An analytical and experimental study. Antone V. Carvalho Follow this and additional works at: http://preserve.lehigh.edu/etd Part of the Geology Commons Recommended Citation Carvalho, Antone V., "Gahnite-franklinite intergrowths at the Sterling Hill zinc deposit, Sussex County, New Jersey: An analytical and experimental study." (1978). Theses and Dissertations. Paper 2136. This Thesis is brought to you for free and open access by Lehigh Preserve. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of Lehigh Preserve. For more information, please contact [email protected]. GAHNITE-FRANKLINITE INTERGROWTHS AT THE STERLING HILL ZINC DEPOSIT, SUSSEX COUNTY, NEW JERSEY: AN ANALYTICAL AND EXPERIMENTAL STUDY by Antone V. Carvalho III A Thesis Presented to the Graduate Committee of Lehigh University in Candidacy for the Degree of Master of Science in Geological Sciences Lehigh University 1978 ProQuest Number: EP76409 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. uest ProQuest EP76409 Published by ProQuest LLC (2015). Copyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code Microform Edition © ProQuest LLC. ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106-1346 CERTIFICATE OF APPROVAL This thesis is accepted and approved in partial fulfillment of the requirements for the degree of Master of Science. i^mr (date) Professor in Charge Chairman of Department ii ACKNOWLEDGMENTS I wish to express my appreciation for the efforts of my advisor Professor Charles B. Sclar, who provided technical guidance and strong sustaining interest throughout the course of this study. I also thank Mr. Robert W. Metsger of the New Jersey Zinc Company and Dr. Paul B. Myers of the Department of Geological Sciences at Lehigh University for their helpful discussions. Mr. Metsger also supervised the selection of samples for this study. The New Jersey Zinc Company generously permitted access to the Sterling Hill Mine. Dr. D. H. Lindsley of. the Department of Earth and Space Sciences at the State University of New York - Stony Brook, kindly made available the facilities of his hydrothermal laboratory where much of the experimental work was carried out. I am grateful to him and to Mr. Jay D. Bass, graduate student at SUNY - Stony Brook, for their assistance with the hydrothermal experiments. Financial support for the use of the electron microprobe in this study was provided by the Bureau of Geology and Topography, Depart- ment of Environmental Protection, of the State of New Jersey through the office of Dr. Kemble Widmer, State Geologist. The costs of experimental work were partly defrayed by a Grant- in-Aid from Sigma Xi, the Scientific Research Society of North America. Mr. A. T. Walker and Mr. A. Romig, graduate students at Lehigh University in the Department of Geological Sciences and the Depart- 111 ment of Metallurgical Engineering, respectively, patiently discussed various aspects of this study with the writer. Dr. John Friel of the Homer Research Laboratories, Bethlehem Steel Corporation and Mr. Douglas Bush, technician in the Department of Metallurgical Engineering at Lehigh University, assisted the writer with data-reduction procedures and with the operation of the electron microprobe. Lastly, I would like to thank my wife, Diane, for her support and understanding throughout the course of this study. IV TABLE OF CONTENTS Pago CERTIFICATE OF APPROVAL ii ACKNOWLEDGMENTS iii LIST OF TABLES viii LIST OF FIGURES ix ABSTRACT 1 INTRODUCTION 4 OBJECTIVES OF THIS STUDY 5 PREVIOUS INVESTIGATIONS 6 GENERAL GEOLOGY OF THE AREA 7 THE STERLING HILL ZINC DEPOSIT 11 Geological Structure and Mineralogy 11 Description of Sample Locations 14 THE SPINEL GROUP OF MINERALS 15 Structural Chemistry 15 Franklinite-Gahnite Exsolution Intergrowths 17 Franklinite-Magnetite Exsolution Intergrowths 28 RESULTS OF ELECTRON MICROPROBE ANALYSIS 41 Frankl ini te 41 Gahnite 49 Franklinite-Gahnite Exsolution Intergrowths 49 Franklinite-Magnetite Exsolution Intergrowths 61 Page RESULTS OF EXPERIMENTAL WORK 70 Background 70 Synthesis of Homogeneous Spinels on the Join ZnAl^O -ZnFe.O. 72 2 4 2 4 Determination of Spinel Composition by Measurement of Lattice Parameter 75 Dry Exsolution Experiments 76 Hydrothermal Experiments 81 Introductory Statement 81 Control of Oxygen Fugacity 81 Methods and Technique 82 Results of Hydrothermal Runs 87 Long Term Dry Run 94 APPLICATION OF ANALYTICAL AND EXPERIMENTAL RESULTS TO THE THERMAL HISTORY OF THE STERLING HILL ZINC DEPOSIT 97 Previous Estimates of the Temperature Attained During Regional Metamorphism 97 Peak Temperature of Metamorphism During the Grenville Orogeny 101 THE MINIMUM TEMPERATURE OF METAMORPHISM AT STERLING HILL 104 Effect of Pressure on Experimental Phase-Equilibrium Diagram 104 Effect of Cationic Defects and Cationic Ordering 105 Compositional Deviations From the Ideal System 106 Attainment of Equilibrium 107 Conclusion of Minimum Temperature of Metamorphism 108 VI Page PROPOSED NEW MINERAL 110 REFERENCES 112 APPENDIX I 116 X APPENDIX II 118 VITA 131 VII LIST OF TABLES Table rage 1 Stratigraphic Column of the Franklin- 10 Sterling Hill Area. 2 Electron Microprobe Analyses of Franklinite 42 (Sample Series 6). / 3 Electron Microprobe Analyses of Franklinite 46 (Sample Series 4). 4 Electron Microprobe Analyses of Discrete 50 Gahnite Crystals. 5 Electron Microprobe Analyses of Gahnite 52 Exsolution Bodies. 6 Broad-Beam Electron Microprobe Analyses of 54 Type C Exsolution Texture. 7 Broad-Beam Electron Microprobe Analyses of 57 Type C Exsolution Texture. 8 Broad-Beam Electron Microprobe Analyses of 59 Type C Exsolution Texture. 9 Broad-Beam Electron Microprobe Analyses of 62 Type B Exsolution Texture. 10 Broad-Beam Electron Microprobe Analyses of 64 Type A Exsolution Texture. 11 Electron Microprobe Analyses of Franklinite- 66 Magnetite Exsolution Intergrowths. 12 X-ray Powder Diffraction Maxima on the 77 Join ZnAl_0 ~ZnFe„0, . 2 4 2 4 13 Results of the Hydrothermal Exsolution 89 Experiments in the System ZnAl C> -ZnFejD,. 2 4 2 4 vm Figure rage 16 Photomicrograph of Franklinite-Magnetite 34 Exsolution Intergrowth. 17 Photomicrograph of Franklinito-Magnetite 35 Exsolution Intergrowth. 18 Photomicrograph of Franklinite-Magnetite 36 Exsolution Intergrowth. 19 Photomicrograph of Franklinite-Magnetite 30 Exsolution Intergrowth. 20 Photomicrograph of Franklinite-Magnetite 39 Exsolution Intergrowth. 21 Theoretical Solvus in the System FeFe„0 - 71 2 4 ZnFeJD,. 2 4 22 Pellet Assembly on Pt-Rh Wire. 74 23 X-ray Diffraction Curves Based on the 78 (220) and (311) Reflections of'Spinel. 24 X-ray Diffraction Curves Based on the 79 (511) and (440) Reflections of Spinel. 25 ao as a Function of Composition Across the 80 ZnAl.O -ZnFe^C- Binary. 2 4 2 4 26 Hematite-Magnetite Buffer Equilibrium Curve. 83 27 Capsule Arrangement Inside Bomb. 85 28 Results of Hydrothermal Runs 1 through 10. 90 29 Results of Hydrothermal Runs 11 through 20. 93 30 Composition of Co-existing Spinels as a 96 Function of Time During Dry Run at 950°C. 31 Phase Equilibrium Diagram for the Fe 0 - 98 Mn_0. -ZnMn-C- -ZnFe„0„. 3 4 2 4 2 4 32 Experimentally Determined Mineral Equilibria 103 for Assemblage Characteristic of Paragneiss. 33 Precambrian Cooling Curve for Grenville 109 Sequence. LIST OF FIGURES Figure Page 1 Geologic Map of the Franklin-Sterling Hill 8 Area. 2 Geologic Map of the Sterling Hill Ore Body. 12 3 Photomicrograph of Gahnite-Franklinite 19 Exsolution Intergrowth. 4 Photomicrograph of Gahnite-Franklinite 20 Exsolution Intergrowth. 5 Photomicrograph of Gahnite-Franklinite 21 Exsolution Intergrowth. 6 Photomicrograph of Gahnite-Franklinite 22 ■ t, Exsolution Intergrowth. 7 Photomicrograph of Gahnite-Franklinite 23 Exsolution Intergrowth. 8 Photomicrograph of Gahnite-Franklinite 24 Exsolution Intergrowth. 9 Photomicrograph of Gahnite-Franklinite 25 Exsolution Intergrowth. 10 Photomicrograph of Gahnite-Franklinite 27 Exsolution Intergrowth. 11 Photomicrograph of Franklinite-Magnetite 29 Exsolution Intergrowth. 12 Photomicrograph of Franklinite-Magnetite 30 Exsolution Intergrowth. 13 Photomicrograph of Franklinite-Magnetite 31 Exsolution Intergrowth. 14 Photomicrograph of Franklinite-Magnetite 32 Exsolution Intergrowth. 15 Photomicrograph of Franklinite-Magnetite 33 Exsolution Intergrowth. IX ABSTRACT The Sterling Hill zinc deposit is a regionally metamor{)hosed stratiform oxide-silicate deposit enclosed in the Procambrian Franklin marble. Spinels, which consist of oriented exsolution intergrowths of gahnite (ideally ZnAl 0 ) and franklinite (ideally ZnFe O.) were collected at four locations in the Sterling Hill mine. The bulk chemical composition of these spinels and the composition of the phases which constitute the intergrowths were determined by broad-beam and point analysis, respectively, with the electron microprobe. These data show that the original homogeneous high-temperature spinels were as aluminous as F80G20. The miscibility gap in the system ZnAl O.-ZnFe 0 was