University of New Mexico UNM Digital Repository Earth and Planetary Sciences ETDs Electronic Theses and Dissertations 7-1-2014 An experimental and petrologic investigation of the source regions of lunar magmatism in the context of the primordial differentiation of the Moon Stephen Elardo Follow this and additional works at: https://digitalrepository.unm.edu/eps_etds Recommended Citation Elardo, Stephen. "An experimental and petrologic investigation of the source regions of lunar magmatism in the context of the primordial differentiation of the Moon." (2014). https://digitalrepository.unm.edu/eps_etds/23 This Dissertation is brought to you for free and open access by the Electronic Theses and Dissertations at UNM Digital Repository. It has been accepted for inclusion in Earth and Planetary Sciences ETDs by an authorized administrator of UNM Digital Repository. For more information, please contact [email protected]. Stephen Matthew Elardo Candidate Institute of Meteoritics, Dept. of Earth & Planetary Science Department This dissertation is approved, and it is acceptable in quality and form for publication: Approved by the Dissertation Committee: Dr. Charles K. Shearer , Chairperson Dr. Carl B. Agee Dr. Zachary D. Sharp Dr. David S. Draper i AN EXPERIMENTAL AND PETROLOGIC INVESTIGATION OF THE SOURCE REGIONS OF LUNAR MAGMATISM IN THE CONTEXT OF THE PRIMORDIAL DIFFERENTIATION OF THE MOON by STEPHEN M. ELARDO B.Sc., Geosciences, Stony Brook University, 2008 M.Sc., Earth & Planetary Sciences, University of New Mexico, 2010 DISSERTATION Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy Earth and Plantary Sciences The University of New Mexico Albuquerque, New Mexico July, 2014 ii Acknowledgements The old saying about it taking a village is no less apropos when talking about a student working toward a doctorate than it is a young child stumbling toward adulthood. Being in a position to devote this many years of my life toward earning a PhD is a luxury many people will simply never be granted, nor is it one I would have had on my own. I owe many people a substantial debt for helping me through the process that resulted in the document that follows and the achievement it represents. I hope that, in lieu of the proper thanks you all actually deserve, the next few lines will suffice in conveying my gratitude… My start in planetary science and experimental petrology, and the experience that led me to come to UNM, began at Stony Brook University, and I thank Francis McCubbin, Hanna Nekvasil, and Don Lindsley for the opportunity to work in the SBU petrology lab and get excited about planetary science while not really knowing what I was doing. My sincere gratitude goes to Francis especially, who has been as much of a friend as he has a mentor and co-advisor from the time we were both students at Stony Brook up to this day. Working alongside Francis has without a doubt made me a better scientist. Most of my publication record owes Francis a beer, as well. I also thank Dave Draper for taking a chance on me as a fairly green master’s student, and for subsequently being a great mentor and friend, as well as one of my biggest advocates. The latter often leads me to wonder what Dave knows about me that I don’t. And of course I owe an immeasurable amount of gratitude to my advisor Chip Shearer, for giving the opportunity to work with him on a PhD, for allowing me the freedom to follow my nose even when at first it looked like I was going down a dead end, for nudging me back on track when I wandered too far off course, and for always being both patient and insightful. Working with Chip the past few years has been a truly enjoyable and instructive experience that I will miss greatly. There are numerous others that deserve recognition as well. I thank the rest of my committee, Carl Agee and Zach Sharp, for their support and assistance. I also thank Carl and the Institute of Meteoritics for access to lunar meteorites without which some of the work below would not have been possible. I thank the rest of the Gang of Six (Chip, Francis, Jim Papike, Paul Burger, and Aaron Bell) for thoroughly enjoyable and insightful weekly meetings. Jim is thanked for both his excellent insight over the years, and specifically for a conversation (or perhaps I should say sales pitch) in 2009 that finally convinced me that staying at UNM for my PhD was the right decision. Paul is thanked for numerous instances of help throughout the years, especially with SIMS analyses. Aaron is thanked for help in the 1-bar lab and for consistently insightful conversations, from which I always walk away having learned something. Mike Spilde is thanked for assistance with the microprobe, and for always being patient with after-hours calls when it appeared disaster had struck. Tracy Paul at Depths of the Earth is thanked for her assistance in keeping the QUICKpress up and running. My external collaborators, listed at the beginning of each chapter, are thanked kindly for their contributions and insight during the completion of each project. Specifically, I thank Lars Borg for numerous conversations (and patience) as we tried to figure out what in the hell the isotopic data in chapter 2 meant. Lee Ann Lloyd, Shannon Clark, and Cindy Jaramillo are thanked for all of their help throughout the years with paperwork, ordering, contracts, supplies, reimbursements, and all of the miscellaneous stuff that had to be done for one reason or another so that the show could go on. iii Nothing in science (or anywhere else, really) can get done without a bankroll. The projects in this dissertation were financially supported by numerous funding organizations. The NASA Cosmochemistry and LASER programs are thanked for grants to Chip Shearer and Francis McCubbin which provided the bulk of the support for this work. Also, the NASA Earth and Space Science program and the New Mexico Space Grant Consortium are thanked for graduate fellowships. Additional funding and support came from a Cosmochemistry grant to Clive Neal, the US Department of Energy, Lunar and Planetary Institute, the Institute of Meteoritics, and the Department of Earth and Planetary Sciences, all of which are kindly thanked. Although it is likely to be deeply shocking to everyone who reads this, I am forced to report that, on occasion, getting a PhD can sometimes be challenging. Fortunately, I am lucky enough to have the support of a superb group of friends at UNM who are traveling the same road and understand the challenges. I have had the pleasure of working alongside many great people in my six years at UNM whom I will call friends for many years to come, but I want to specifically thank Kathleen Vander Kaaden, Alison Santos, Laura Burkemper, and Nina Lanza for support and friendship that goes beyond words. I hope that I have been, and in the future can be, just as important to you as you are to me. Lastly, as I would never go against the family, I want to thank those who brought me into this world and who, I’ve been told, could just as easily take me out. Words like ‘lucky’, ‘blessed’, and ‘fortunate’ do not adequately convey how I feel about having the parents and brother that I do. Never once was I told that there was something I could not do, nor that my curiosity about the world and the stars and the planets wasn’t important or practical or worth exploring, nor that I should pursue a career that would make me more money instead of one that makes me happy. For everything you have given me, mom, dad, and Drew, thank you from the bottom of my heart. It is a debt that truly cannot be repaid, but one that I assure you I will pay forward. And to Amy, my best friend, my wife, my love, my everything, I owe you more than I could ever possibly repay, most importantly for your dedication and patience. I so look forward to finding out what the years ahead hold for us. And “Dr. and Dr.” sure does have a nice ring to it… “We make our world significant by the courage of our questions and the depth of our answers.” -Carl Sagan iv For Mom and Dad Around the world and back again… v AN EXPERIMENTAL AND PETROLOGIC INVESTIGATION OF THE SOURCE REGIONS OF LUNAR MAGMATISM IN THE CONTEXT OF THE PRIMORDIAL DIFFERENTIATION OF THE MOON By Stephen M. Elardo B.Sc., Geosciences, Stony Brook University, 2008 M.Sc., Earth and Planetary Sciences, University of New Mexico, 2010 Ph.D., Earth and Planetary Sciences, University of New Mexico, 2014 ABSTRACT The primordial differentiation of the Moon via a global magma ocean has become the paradigm under which all lunar data are interpreted. The success of this model in explaining multiple geochemical, petrologic, and isotopic characteristics lunar geology has led to magma oceans becoming the preferred model for the differentiation of Earth, Mars, Mercury, Vesta, and other large terrestrial bodies. The goal of this work is to combine petrologic analyses of lunar samples with high pressure, high temperature petrologic experiments to place new and detailed constraints the petrogenetic processes that operated during different stages of lunar magmatism, the processes that have acted upon these magmas to obscure their relationship to their mantle source regions, and how those source regions fit into the context of the lunar magma ocean model. This work focuses on two important phases of lunar magmatism: the ancient crust- building plutonic lithologies of the Mg-suite dating to ~4.3 Ga, and the most recent known mare basaltic magmas dating to ~3 Ga.