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University of Alberta Geology, geochronology, thermobarometry, and tectonic evolution of the Queen Maud block, Churchill craton, Nunavut, Canada by Daniel B. Tersmette A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science Department of Earth and Atmospheric Sciences ©Daniel B. Tersmette Spring 2012 Edmonton, Alberta Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission. Dedication For Tawny Abstract The Queen Maud block is divided into two crustal belts. The western Perry River belt is dominated by Mesoarchean to Neoarchean granitic gneisses and supracrustal rocks; it was incorporated into the Rae domain by at least 2.46 Ga. The eastern Paalliq belt is dominated by the 2.52-2.45 Ga Queen Maud granitoids and the 2.45-2.39 Ga Sherman supracrustal sequence, both of which were formed on Neoarchean crust of the Rae domain. Slave-Churchill collision and convergence occurred ca. 2.43-2.35 Ga resulting in granulite-facies metamorphism, regional scale N-S trending strike-slip shearing, and minor crustal melting in the Queen Maud block. Post-collisional magmatism occurred ca. 2.32 Ga. Between 2.3 and 2.1 Ga mafic magmatism and monazite growth occurred in the western Queen Maud block, possibly as a result of continental rifting. The 2.01-1.91 Ga Thelon Orogeny affects only the western-most Queen Maud block, where 1.93 Ga metamorphism and very weak deformation are preserved. Acknowledgements Funding for this thesis was provided by the Polar Continental Shelf Project and an NSERC discovery grant to Dr. Tom Chacko. The University of Alberta funded the author through a teaching assistantship. There are many people to thank for their support in preparing this thesis. My supervisor, Tom Chacko, deserves huge thanks for his ceaseless enthusiasm, constructive feedback, and constant support over the last two years. I would also like to thank Tom for simply allowing me to be part of such an exciting project. It is not every Master‘s student who has the opportunity to participate in such thrilling, discovery-style research as was provided by the Queen Maud block. I also thank Larry Heaman, not only for his efforts as a member of my supervisory committee but also for discussions throughout the course of the research and for assistance with zircon grain mount preparation. Thank you to Claire Currie for her review of this thesis as the external examiner on the supervisory committee. Field work was greatly aided by the staff at The Arctic Islands Lodge in Cambridge Bay; in particular, Jane Cunningham, who unknowingly became our field manager. I would also like to thank our trustworthy helicopter pilot, Guy Fisher for ensuring our safety during field activities. Rameses D‘Souza, Mark Labbe, and David Pirie all assisted in thin-section preparation and rock crushing. Zircon separation and grain mount preparation were made possible with the assistance of Barry Herchuck, Judy Schultz, and Angus Duncan. Thank you also to Sergei Matveev and De-Ann Rollings for their assistance with microprobe analysis and BSE imaging. A thank you to Rob Creasar for his work on the Sm-Nd isotopic analyses (also thank you to Tom for not making me write an additional chapter when these data became available in December, 2011). Without the assistance of Andy DuFrane, the U-Pb dating conducted for this study would not have been possible; I offer Andy a sincere thank you for his assistance during our many long days on the laser. Behind the scenes there are many more people to thank. I would like to thank Benoit Beauchamp, Dave Pattison, and Jerry Osborn from the University of Calgary. Though they may not know, their teaching and enthusiasm inspired me to further my education at the University of Alberta. My family, who have supported me and acted as a sounding board over the last two years, helped me to maintain my sanity. My fiancée, who somehow did not get tired of hearing about the Queen Maud block and who stuck with me while I lived away from home, deserves the greatest thanks. Table of Contents Title Dedication Abstract Acknowledgements Table of Contents List of Tables List of Figures List of Abbreviationsix CHAPTER 1 – Introduction ............................................................................................ 1 1.1 – Objectives .............................................................................................................. 2 1.2 – Geology of the Churchill Province...................................................................... 3 1.3 – The Queen Maud block ....................................................................................... 5 1.3.1 – Defining the Queen Maud block ..................................................................... 5 1.3.2 – Previous research in the Queen Maud block .................................................. 6 1.3.3 – Economic geology of the Queen Maud block .................................................. 8 CHAPTER 2 – Field relationships and petrography ................................................... 11 2.1 – Methodology ....................................................................................................... 11 2.2 – Geology of the Queen Maud block ................................................................... 12 2.2.1 – Lithology ....................................................................................................... 12 2.2.2 – Tectono-metamorphism ................................................................................. 13 CHAPTER 3 – U-Pb geochronology ............................................................................. 26 3.1 – Methodology ....................................................................................................... 26 3.2 – U-Pb age dating results ...................................................................................... 28 3.3 – Detrital zircon results ........................................................................................ 43 CHAPTER 4 – Geothermobarometry ........................................................................... 64 4.1 – Methodology ....................................................................................................... 64 4.1.1 – Net-transfer and Fe-Mg exchange geothermobarometry .............................. 64 4.1.2 – Reintegrated feldspar thermometry ............................................................... 66 4.2 – Results ................................................................................................................. 67 CHAPTER 5 – Evolution of the Queen Maud Block ................................................... 82 5.1 – A geological map of the Queen Maud block .................................................... 82 5.2 – Metamorphic history of the Queen Maud block ............................................. 89 5.2.1 – Archean metamorphism ................................................................................ 89 5.2.2 – Metamorphism: ca. 2.52-2.45 Ga ................................................................. 89 5.2.3 – Metamorphism: ca. 2.43-2.42 Ga ................................................................. 90 5.2.4 – Regional metamorphism: 2.39-2.35 Ga Arrowsmith Orogeny ..................... 91 5.2.5 – Post Arrowsmith metamorphism: 2.35-2.10 Ga ........................................... 92 5.2.6 – Thelon Orogeny: 2.01-1.91 Ga ..................................................................... 93 5.2.7 – The Trans-Hudson Orogen: ca. 1.9-1.8 Ga metamorphism ......................... 94 5.3 – A review of previous models for the Slave-Churchill relationship ................ 95 5.3.1 – 2.01-1.91 Ga collision of the Slave and Churchill cratons ........................... 95 5.3.2 – 2.01-1.91 Ga intracontinental orogenesis .................................................... 97 5.4 –A new model for the evolution of northwestern Laurentia ............................. 99 5.4.1 – The Archean .................................................................................................. 99 5.4.2 – Pre-collisional tectono-magmatism: 2.52-2.45 Ga ..................................... 102 5.4.3 – Slave-Churchill collision and convergence: 2.43-2.35 Ga ......................... 103 5.4.4 – Post-collision magmatism: 2.32 Ga ............................................................ 105 5.4.5 – Continental rifting ca. 2.3-2.1 Ga ............................................................... 106 5.4.6 – Thelon Orogeny: 2.01-1.91 Ga ................................................................... 106 CHAPTER 6 – Conclusion ........................................................................................... 113 6.1 – Summary ........................................................................................................... 113 6.2 – Further Research ............................................................................................