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Using Paleomagnetism, Geochronology and Numerical Methods to Create and Assess Spatiotemporal Geological Relationships Through Earth History

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Using Paleomagnetism, Geochronology and Numerical Methods to Create and Assess Spatiotemporal Geological Relationships Through Earth History SPACE AND TIME: USING PALEOMAGNETISM, GEOCHRONOLOGY AND NUMERICAL METHODS TO CREATE AND ASSESS SPATIOTEMPORAL GEOLOGICAL RELATIONSHIPS THROUGH EARTH HISTORY By ANTHONY FRANCIS PIVARUNAS A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2019 © 2019 Anthony Francis Pivarunas To my family, for supporting my unique co-obsession with magnets and rocks, Scott, for opening the door, and Joe, for guiding me through it ACKNOWLEDGMENTS I thank my parents, for supporting me the entire time. Your encouragement, advice, and love are amazing. My siblings, for talking, listening, and loving. My extended family, for asking me “What is the actual use of what you’re doing, Anthony?” enough times that I finally could answer it. I need to thank the SUNY Geneseo Geology department, in particular all the amazing teachers. Scott, Dori, Nick, Amy, Jeff, Ben, and Nancy, you helped guide me into geology. Particular thanks and blame for turning me onto paleomagnetism goes to Scott. It’s all your fault. To the Geowizards, there is no one I’d rather confound the Geneseo Physics department with. The long jaunt south was all started by Rob Van der Voo, my academic grandfather, who took the time to reply to my fumbling email and get me in touch with Florida. Thank you, Rob. I want to thank the entire University of Florida Geological Sciences department. Special thanks to the unsung heroes in the office and workshops: Pam, Carrie, Kristin, Diana and Dow and Ray. Thanks to all my committee members: Dave (for teaching me how to be a careful scientist), Alessandro (for teaching me how to be a creative scientist), Ray (for teaching me how to be a useful scientist), and Jim (for teaching me to be a communicative scientist). They all did all those things, but those are the particular parts. To all the graduate and undergraduate students at UF during my time here, thanks for being great friends and colleagues. All my paleomagical lab mates: Kara, Scott, Austin, Erin, Aubrey, Kelli, Claudia, Landon, and Rachel. Now I need to try to put into words my deep thanks to my advisor, Joe Meert. You have supported me, advised me, pushed me, and guided me unfailingly over the past years. You even saved me from being shot during field work! I would not be where I am without your constant example and teaching. Thanks for everything, Joe. 4 TABLE OF CONTENTS page ACKNOWLEDGMENTS ...............................................................................................................4 LIST OF TABLES ...........................................................................................................................8 LIST OF FIGURES .........................................................................................................................9 LIST OF ABBREVIATIONS ........................................................................................................12 ABSTRACT ...................................................................................................................................14 CHAPTER 1 INTRODUCTORY REMARKS .................................................................................................16 1.1 Paleogeography .................................................................................................................16 1.1.1 Paleomagnetism ......................................................................................................17 1.1.2 Geochronology .......................................................................................................18 1.2 Research Objectives .....................................................................................................18 1.3 Overview ...........................................................................................................................20 2 PALEOMAGNETISM AND GEOCHRONOLOGY OF MAFIC DYKES FROM THE SOUTHERN GRANULITE TERRANE, INDIA: EXPANDING THE DHARWAR CRATON SOUTHWARD .....................................................................................................22 2.1 Introduction .......................................................................................................................22 2.1.1 Rationale .................................................................................................................22 2.1.2 Regional Geologic Setting and Area of Study .......................................................23 2.1.3 Previous Paleomagnetic Work ...............................................................................25 2.2 Methods ............................................................................................................................27 2.2.1 Paleomagnetic Analysis ..........................................................................................27 2.2.2 U–Pb Geochronology .............................................................................................28 2.3 Results...............................................................................................................................29 2.3.1 Geochronology .......................................................................................................29 2.3.1.1 Site 10 geochronology ..................................................................................29 2.3.1.2 Site 35 geochronology ..................................................................................30 2.3.2 Paleomagnetism ......................................................................................................30 2.3.2.1 Low to moderate temperature/coercivity components .................................30 2.3.2.2 Steeply inclined directions ...........................................................................31 2.3.2.3 Shallowly inclined directions .......................................................................33 2.3.2.4 Dual polarity intermediate directions ...........................................................34 2.3.2.5 Other directions ............................................................................................35 2.4 Discussion .........................................................................................................................37 2.4.1 Paleomagnetism at Scale ........................................................................................37 2.4.2 The South Indian “bar code” ..................................................................................38 5 2.4.3 The Northern Block of the SGT and the Dharwar Craton: A Metamorphosed Chip off the Old Block .................................................................................................41 2.5 Conclusions.......................................................................................................................44 3 PALEOMAGNETIC RESULTS FROM SINGHBHUM CRATON: REMAGNETIZATION, DEMAGNETIZATION, AND COMPLICATION .......................68 3.1. Introduction ......................................................................................................................68 3.1.1 India: A Rich and Complex Precambrian Record ..................................................68 3.1.2 Geologic Setting .....................................................................................................70 3.1.3 Prior Paleomagnetic Work .....................................................................................72 3.2. Methods ...........................................................................................................................74 3.3. Results..............................................................................................................................75 3.3.1 Magnetic Overprints ...............................................................................................75 3.3.2 NW-Shallow Reverse Magnetization .....................................................................75 3.3.3 Steeply-Inclined Dual Polarity Magnetic Data .......................................................78 3.3.3.1 NNE-trending dykes with intermediate-steep dual polarity magnetizations ......................................................................................................79 3.3.3.2 WNW-trending dykes with intermediate-steep dual polarity magnetizations ......................................................................................................80 3.3.3.3 Steep magnetizations in host rocks and dyke margins .................................81 3.2.3.4 A unified model for Singhbhum intermediate-steep paleomagnetism .........82 3.3.4 Dual Polarity NE-SW Shallow Magnetization .......................................................82 3.3.5 Easterly, Intermediate Reverse Direction ...............................................................84 3.3.6 Northerly, Intermediate Normal Direction .............................................................86 3.4. Discussion ........................................................................................................................87 3.4.1 Magnetic Relationships within Singhbhum Craton ................................................87 3.4.2 Comparison with Other South Indian Block Cratons .............................................91 3.5. Conclusions......................................................................................................................93 4 ASSESSING THE INTERSECTION/REMAGNETIZATION PUZZLE
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