Noble Gas Chronology of Meteorites: Brachinites, Ureilites, and Chelyabinsk Item Type text; Electronic Dissertation Authors Beard, Sky 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, presentation (such as public display or performance) of protected items is prohibited except with permission of the author. Download date 09/10/2021 07:41:47 Link to Item http://hdl.handle.net/10150/631308 1 NOBLE GAS CHRONOLOGY OF METEORITES: BRACHINITES, UREILITES, AND CHELYABINSK by Sky Beard __________________________ Copyright © Sky Beard 2018 A Dissertation Submitted to the Faculty of the DEPARTMENT OF PLANETARY SCIENCES In Partial Fulfillment of the Requirements For the Degree of DOCTOR OF PHILOSOPHY In the Graduate College THE UNIVERSITY OF ARIZONA 2018 2 THE UNIVERSITY OF ARIZONA GRADUATE COLLEGE As members of the Dissertation Committee, we certify that we have read the dissertation prepared by SkyBeard, titled Noble Gas Chronology of Meteorites: Brachinites, Ureilites, and Chelyabinsk and recommend that it be accepted as fulfillingthe dissertation requirement for the Degree of Doctor of Philosophy. Date: (9/24/2018) Date: (9/24/2018) Date: (9/24/2018) Date: (9/2412018) d 3 STATEMENT BY AUTHOR This dissertation has been submitted in partial fulfillment of the 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 allowable without special permission, provided that an accurate acknowledgement of the 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 copyright holder. SIGNED: Sky Beard 4 ACKNOWLEDGMENTS Mom, you always support whatever I want to do and I cannot tell you how much I appreciate you. You want everyone to be happy and sacrifice so much. Please remember to take care of yourself, too! I miss making you laugh. Lee, thanks for always being willing to do whatever is needed. I am so happy you have a career you love and am proud of how hard you are working. Thanks for helping the family when needed and thank you for our fun talks that help make the distance from home seem shorter. Misty, I know you are working so hard to make things better for your family. Do not give up. I admire that and know your effort will be rewarded. You are so fun and sweet, I miss you! Meadow, I always appreciate your kindness and open invitations to visit you. You are so accommodating and always make my visits feel like home. Brooke, I am happy to see all the great changes you have made in your life and to see you achieve your goals. Thank you for helping others as much as you do and for being a positive influence. Prarie, thank you for always welcoming me to stay at your home when I visit, coloring amazing pictures, and ensuring that I’m fed all our homemade favorites! I enjoy our laughs together and look forward to visiting soon. To all of you, thank you for your encouragement! I love you. Tim Swindle: thank you for being the most wonderful advisor I could have imagined. I am very thankful for the opportunity to learn from you as a scientist and friend. I have learned so much under your guidance and will always be grateful. Tom Zega: thank you for always asking such good questions and making each conversation a fun learning experience. Mike Nolan: thank you for filling in last minute to serve on my committee before even knowing me. Your positivity always is always encouraging. Vic Baker: I always enjoy our chats, work related or not. Your anecdotes and philosophy are always enlightening and refreshing. Barbara Cohen: thank you for your helpful discussions about experimental techniques, helping with analysis, and taking the extra responsibility of being on my committee. Ken Domanik: You are always happy to help me understand microprobe related matters. Your enthusiasm is inspiring. Clark Isachsen: Thank you for taking care of whatever needed to be tested or fixed in the lab. I would be still be in the lab changing gaskets and leak testing if it was not for your help and expertise. You have always been enthusiastic about solving problems and I have learned a lot from you. Thank you all for your patience and understanding. Agli miei amici, la famiglia Vimercati: Michele, Mary Cruz, Lara, y Ylena, grazie per tutto. Avete avuto un profondo impatto sulla mia vita e ti sono molto grato. Spero che stiate tutti bene, mi mancate a caro prezzo. Vi voglio bene! Asia, grazie mille pet il tuo disegno dello spettrometro, ma piu importante la tua amicizia e cura. Sawadi nong Ploy. Khap khun thuk yang. Khun nang lae narak mak, lae guan teen mak mak. 5 TABLE OF CONTENTS LIST OF FIGURES.........................................................................................................................7 LIST OF TABLES.........................................................................................................................10 ABSTRACT...................................................................................................................................11 CHAPTER 1: INTRODUCTION..................................................................................................13 1.1 Ordinary Chondrites………………………………………..………………………………….……….. 13 1.2 Brachinites……………………….…………………………………………………………………………..18 1.3 Ureilites………………………..……………………………………………………………………..………. 22 1.4 Thesis Structure and Logistics………………………..………………..………………………………24 CHAPTER 2: TECHNIQUES AND SAMPLES......................................................................... 26 2.1 Argon-Argon Background.......................................................................................... 26 2.2 Ar-Ar Experimental Design and Data Aquisition........................................................36 2.3 Cosmic-Ray Exposure Background............................................................................ 41 2.4 CRE Experimental Design and Data Aquisition..........................................................46 2.5 Oxygen Isotopes ……………………………………………………………………………………………52 2.6 Samples………………………………………………………………..…………………………….…………54 CHAPTER 3: AR-AR DATA REDUCTION EXAMPLE.....................................................................................................................................63 3.1 Gas Extraction..............................................................................................................63 3.2 Data Corrections..........................................................................................................64 CHAPTER 4: AR-AR OF CHELYABINSK................................................................................73 4.1 Introduction..................................................................................................................73 4.2 Ar-Ar Analysis.............................................................................................................74 4.3 Ar-Ar Results of Chelyabinsk......................................................................................76 4.4 Impact Age Discussion................................................................................................87 4.5 Conclusions................................................................................................................. 97 CHAPTER 5: AR-AR DIFFICULTIES WITH BRACHINITES................................................ 99 5.1 Introduction................................................................................................................. 99 5.2 Analysis....................................................................................................................... 99 5.3 Brachinite Ar-Ar Results.......................................................................................... 101 5.4 Ar-Ar Discussion...................................................................................................... 105 5.5 Brachinite Argon Conclusion....................................................................................109 CHAPTER 6: COSMIC-RAY EXPOSURE AGES OF UREILITES.........................................110 6.1 Introduction................................................................................................................110 6.2 Methods......................................................................................................................114 6.3 Ureilite Exposure Age Results...................................................................................118 6.4 Discussion..................................................................................................................122 6.5 Conclusion.................................................................................................................125 6 CHAPTER 7: COSMIC-RAY EXPOSURE AGES OF BRACHINITES AND OTHER ACHONDRITES........................................................................................................................ 127 7.1 Introduction............................................................................................................... 127 7.2 Brachinite, Brachinite-like, and Ungrouped Classifications..................................... 132 7.3 UMA Noble Gases.....................................................................................................137