UNLV Theses, Dissertations, Professional Papers, and Capstones 8-31-2015 An Investigation into Transitions in Clay Mineral Chemistry on Mars Seth Gainey University of Nevada, Las Vegas Follow this and additional works at: https://digitalscholarship.unlv.edu/thesesdissertations Part of the Geochemistry Commons, Geology Commons, and the Mineral Physics Commons Repository Citation Gainey, Seth, "An Investigation into Transitions in Clay Mineral Chemistry on Mars" (2015). UNLV Theses, Dissertations, Professional Papers, and Capstones. 2475. http://dx.doi.org/10.34917/7777303 This Dissertation is protected by copyright and/or related rights. It has been brought to you by Digital Scholarship@UNLV with permission from the rights-holder(s). You are free to use this Dissertation in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s) directly, unless additional rights are indicated by a Creative Commons license in the record and/or on the work itself. This Dissertation has been accepted for inclusion in UNLV Theses, Dissertations, Professional Papers, and Capstones by an authorized administrator of Digital Scholarship@UNLV. For more information, please contact [email protected]. AN INVESTIGATION INTO TRANSITIONS IN CLAY MINERAL CHEMISTRY ON MARS By Seth R. Gainey Bachelor of Science in Geology St. Cloud State University 2009 Master of Science in Geology University of Oklahoma 2011 A dissertation submitted in partial fulfillment of the requirements for the Doctor of Philosophy – Geoscience Department of Geoscience College of Sciences The Graduate College University of Nevada, Las Vegas August 2015 Copyright by Seth R. Gainey, 2015 All Rights Reserved Dissertation Approval The Graduate College The University of Nevada, Las Vegas May 1, 2015 This dissertation prepared by Seth Gainey entitled An Investigation into Transitions in Clay Mineral Chemistry on Mars is approved in partial fulfillment of the requirements for the degree of Doctor of Philosophy – Geosciences Department of Geosciences Elisabeth M. Hausrath, Ph.D. Kathryn Hausbeck Korgan, Ph.D. Examination Committee Chair Graduate College Interim Dean Joel Hurowitz, Ph.D. Examination Committee Member Oliver Tschauner, Ph.D. Examination Committee Member Arya Udry, Ph.D. Examination Committee Member Paul Forster, Ph.D. Graduate College Faculty Representative ii ABSTRACT AN INVESTIGATION INTO TRANSITIONS IN CLAY MINERAL CHEMISTRY ON MARS by Seth R. Gainey Dr. Elisabeth Hausrath, Examination Committee Chair Assistant Professor of Geoscience University of Nevada, Las Vegas This dissertation is comprised of three studies investigating clay mineralogy on, or near the martian surface, with an introductory chapter, introducing and linking the three studies. Chapter two is on the subject of clay mineral synthesis, including Fe/Mg clay minerals which have been detected at multiple locations across the southern highlands. These Fe/Mg clay minerals have been previously interpreted as forming in anoxic/reducing environments, conducive to the preservation of organic matter. The results of this study suggest that the previous interpretation of Fe/Mg-rich clay as requiring anoxic/reducing conditions may not be accurate, as the minor presence of Mg (below what is found in many naturally occurring nontronites) allowed for the rapid precipitation of Fe-rich clay minerals under oxidized conditions. These results would prompt a reinterpretation of clay-bearing environments on the martian surface and may explain the relative dearth of detectable organic carbon on Mars. Chapter three is on the subject of nontronite dissolution kinetics and its implications for Mars. Nontronite is a Fe-rich smectite and has been identified on the iii martian surface with orbital Visible Near InfraRed (VNIR) spectrometers. The results of this study suggest nontronite is stable relative to the primary minerals in basalt under acidic and oxidizing conditions and once formed may remain on the martian surface for significant durations. Nontronite dissolution is more rapid than other clay minerals, such as kaolinite and montmorillonite (under acidic and oxidizing conditions). These results suggest the dissolution of mixed clay units may produce stratigraphy (e.g. Al-rich clay minerals overlying Fe/Mg-rich phyllosilicates) similar to that observed in the Mawrth Vallis region and other localities on the martian surface and may therefore imply surficial weathering. In chapter four, reactive transport modeling was applied to investigate potential weathering profiles detected at, or near the martian surface. These result suggest that when Fe/Mg rich clay minerals are exposed to pedogenic conditions they alter to montmorillonite and kaolinite (i.e. the Al-rich overlying layer). The models included four scenarios where the parent materials consisted of: nontronite; nontronite and montmorillonite; nontronite and saponite and pure saponite. In all scenarios and in all cases (i.e. regardless of temperature, pH and flow rate) the weathering of the parent material resulted in the precipitation of an Al-rich layer. Similar stratigraphy has been observed in the Mawrth Vallis region and other localities on the martian surface. These results would suggest that the observed transitions in clay mineral chemistry are the result of weathering, implying the surface of Mars may have been exposed to long-term liquid water at its surface. iv ACKNOWLEDGEMENTS I would like to first thank my father, for ultimately influencing my path in geoscience. It was my father that inspired me to pursue this tremendous undertaking and I wish he would have seen me finish. With that said, the list of support and thanks are extensive, and I truly apologize if I have missed anyone. I would like to thank my family for their continued support through this process. I definitely had some ups and downs during this undertaking and if it was not for their support I would have never been able to reach this point. I would also like to thank Susan Nguyen who was extremely supportive of me and always willing to listen. She is a true inspiration to not only me, but many in her field. I do not have enough thanks for Dr. Elisabeth Hausrath my committee chair. She was always willing to help me through this process. I lost count of how many hours I sat in her office, where she helped me with my research, writing and what to expect in the future. I do not believe a student could ask for a better advisor. I would like to give my thanks to Dr. Joel Hurowitz, who was my mentor for two summers at the Jet Propulsion Laboratory. It was that first summer at JPL where I got kicked into gear on my research. I had a lot of fun and learned a lot that summer, and when I got to UNLV it felt like I hit the deck running. I would like to thank Dr. Oliver Tschauner for all of his help on these manuscripts. Dr. Tschauner was the man that got me interested in X-Ray diffraction. It was in his class where we ran my first sample with powder diffraction. Now, I don’t even know how many samples are in that folder or hour many hours I logged on that machine. v My committee has been a tremendous help during this process. Paul Forster, you were always more than willing to help me and always positive when we met. Scott Nowicki, provided me with skills I probably would not have learned otherwise, and helped me expand my knowledge beyond Mars. Arya Udry, you have always been willing to meet and put the extra time aside to read my materials and better my research. I would like to thank my office mates. Chris Adcock, who I probably argued with more than anybody I have ever met, but none the less was a tremendous help in my progression. Chris was one year ahead of me and I essentially followed in his path. Valerie Tu, who is probably one of the hardest working people I have ever met, kept a smile on my face and motivated. Michael Steiner, who at first almost never spoke became a friend to whom I probably talk to the most. Fritz Freudenberger, Courtney Bartlett, Brandon Guttery and all of my other office mates over the years, I thank you! Lastly, I need to thank all the sources of funding that made this research possible. This material is based upon the work supported by the National Aeronautics and Space Administration under Grant No. NNX10AN23H issued through the NASA Training Grant: National Space Grant College and Fellowship Program (Space Grant) and the Mars Fundamental Research Program Grant No. NNX12AH96G. I would also thank the University of Nevada, Las Vegas’s Graduate and Professional Student Association, Nevada Space Grant, the Jet Propulsion Laboratory and Argonne National Laboratory. On to the science… vi TABLE OF CONTENTS ABSTRACT………………………………………………………….…………..………iii ACKNOWLEDGMENTS……………………………………………………….………..v LIST OF TABLES..……………………………………………………………….……xiii LIST OF FIGURES………………………………………..……………………….……xv CHAPTER ONE INTRODUCTION AND OVERVIEW…………...……………………1 CHAPTER TWO CLAY MINERALS DETECTED ON MARS CAN FORM IN ENVIRONMENTS THAT MAY DESTROY ORGANIC BIOSIGNITURES………………………………………………………………….……..7 Abstract……………………………………………………………………………………7 Introduction………………………………………………………………………..………8 Methods………………………………………………………………………………..…11 Results and Discussion……………………………………………………………..……11 Conclusions………………………………………………………………………………14 Acknowledgments………………………………………………………………..………14 Tables………………………………………………………………………………….…16 Figures...…………………………………………………………………………….……17 CHAPTER THREE NONTRONITE DISSOLUTION