Geochemical, Isotopic, and Mineralogical Characterization of the Frobisher Suite Mafic
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Geochemical, Isotopic, and Mineralogical Characterization of the Frobisher Suite Mafic- Ultramafic Sills, Southern Baffin Island, Nunavut, with Implications for Metallogenic Potential by Dustin Andrew Liikane, B.Sc.H. A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science Ottawa-Carleton Geoscience Centre and Department of Earth Sciences Carleton University Ottawa, Ontario © 2017 Dustin Andrew Liikane Dedication In loving memory of my brother, Matthew Rein Liikane, who supported me throughout the duration of this thesis project, both in this world, and from the next. April 2, 1993 - March 22, 2015 ! D.A. Liikane, M.Sc. thesis Frontispiece ! Layered Mafic-Ultramafic sill, Markham Bay An aerial photograph of one of the more majestic-looking layered mafic- ultramafic sills, located in Markham Bay, Meta Incognita Peninsula, southern Baffin Island, Nunavut. The sill is overturned, such that the mafic unit forms the structural base of the intrusion, and the thin ultramafic component is situated on top. The sill is hosted in metasedimentary quartzite (white weathering - bottom) and psammite (rusty-brown weathering – top) units of the Lake Harbour Group. !iii D.A. Liikane, M.Sc. thesis Abstract The Frobisher Suite is a newly recognized magmatic province comprised of mafic-ultramafic sills in southern Baffin Island, Nunavut. The sills are emplaced into the metasedimentary strata of the middle Paleoproterozoic Lake Harbour Group, and vary in thickness from several meters to hundreds of meters. Based on major and trace element chemistry, the Frobisher Suite can be divided into eight geochemical groups. The major geochemical groups indicate melting occurred to differing degrees within a mantle plume head, at various depths below the Meta Incognita microcontinent at ca. 1900 Ma. A number of sills formed via injections of multiple, distinct magma types, some of which were influenced by subcontinent lithospheric mantle. Disseminated sulphides are present in the sills, and in some cases, the adjacent host psammite. At this stage, the Frobisher Suite may be considered to be part of its own Large Igneous Province (LIP), termed the “Frobisher LIP.” !iv D.A. Liikane, M.Sc. thesis Acknowledgements First off, I would like to graciously thank my thesis supervisors Dr. Richard Ernst (Carleton University), Dr. Marc St-Onge (Geological Survey of Canada), and Dr. Bruce Kjarsgaard (Geological Survey of Canada) for all of their guidance, support, patience and encouragement throughout the duration of this M.Sc. project. Thank you to all the enthusiastic field assistants and fellow mappers, most of whom assisted with sample collection: Timothy Chadwick, Dr. Owen Weller, Dr. Brenden Dyck, Dr. Diane Skipton, Terry Milton, Sean Noble-Nowdluk, Tyler Rowe, Angela Ford, Harry Ireyak, Alia Bigio, and Randy Hinanik. Thank you to Jerry Nuttall and Gerard Hartery from Universal Helicopters for their safe and professional air-support in the field. Thanks to the camp cook, Debra Guilfoyle, for providing high quality and diverse meals, daily, which kept me fuelled for the two summers of fieldwork. Thanks to the Polar Continental Shelf Program for providing logistical support. A special thanks to Holly Steenkamp (CNGO) and David Mate (CNGO) for overseeing the process for obtaining thin sections and bulk-rock geochemical data. Thanks to Celine Gilbert for data-management in the field, as well as later correspondence with regard to Inuit place names, used to name the Killapait and Chidliak sills. Thanks to Micheal Burns (GSC) for carefully preparing samples (e.g. trimming, slabbing) and thin section blocks prior to shipment. Thanks to Vancouver Petrographic for providing quality thin sections and to ALS Chemex for obtaining precise and accurate geochemical data from the samples. Thank !v D.A. Liikane, M.Sc. thesis you to microprobe technician Peter Jones for his time and expertise in obtaining mineral geochemistry and back-scatter electron images. A big thanks to Nicole Rayner (GSC) for assistance in attempting to date the Frobisher suite. While not every attempt panned out, due to lack of igneous zircons, the minimum crystallization age of 1900 Ma obtained from magmatic zircons in the Killapait sill was key in the regional comparison and modelling sections of the thesis. Also, thank you to the other geochronology staff for their contributions to the U-Pb dating process of the Frobisher suite, specifically, Julie Peressini, Dr. Bill Davis, Tom Pestaj, Pat Hunt, and Carole Lafontaine. I greatly appreciate the thorough and insightful reviews of the Summary of Activities paper [i.e. Liikane et al. (2015)] by Drs. Thomas Skulski (GSC) and Tony Peterson (GSC), and thanks to Tammy Sifer for assistance formatting the text and figures for publication. A special thanks to Angela Ford for her GIS expertise and assistance with geological map preparation. Thanks to Douglas Oneschuk for plotting maps and conference posters. Thank you to Dr. Natasha Wodicka for taking the time to sit down with me and discuss the evolution of the syn-magmatic sedimentary basin adjacent to the Meta Incognita microcontinent, and thanks to Dr. Fred Gaidies for discussing the metamorphism of mafic to ultramafic rocks. Thank you to PhD candidates Nico Kastek and Chris Rogers for discussions on geochemistry. !vi D.A. Liikane, M.Sc. thesis A special thanks to the Geological Survey of Canada (GSC), Canada Nunavut Geoscience Office (CNGO), Carleton University, Ernst Geosciences, and the LIPs-Supercontinent Reconstruction Project for funding this project. Thank you to defence committee members Dr. Richard Ernst, Dr. James Mungall, Dr. Sarah Dare, and Dr. Ian Honsberger for their participation in the defence process, and for insightful comments and suggestions. Lastly, I would like to thank friends and family for their support throughout the duration of my master’s degree program. And thank you to my girlfriend, Pamela Iraheta-Muñiz, for her unwavering support and encouragement during the writing process of the thesis. !vii D.A. Liikane, M.Sc. thesis Method of Presentation The body of the thesis is presented in four chapters (Chapters 3 & 5-7), with each focusing on separate aspects of the Frobisher suite mafic, ultramafic, and mafic-ultramafic sills of southern Baffin Island, Nunavut. They are prefaced by an introduction (Chapter 1) and background (Chapter 2), and followed by a discussion, conclusions and future recommendations (Chapter 8). Between Chapters 3 and 5 there is also an overview of the methods used in the completion of this thesis (Chapter 4). Chapter 1 – A brief introduction to the study area, and the purpose and objectives of the study. Chapter 2 – A detailed background of: (1) Large Igneous Provinces (LIPs), describing all of their components and models of formation; (2) Layered intrusions, including their geometry, distribution and mechanisms of formation; (3) Mafic-ultramafic intrusion-hosted mineral deposits, mainly focused on Ni-Cu-PGE mineralization; and (4) Metamorphism of rocks mafic to ultramafic in composition. Chapter 3 – Introduces the Meta Incognita microcontinent and the Paleoproterozoic Trans-Hudson orogen. The regional geology of the Québec- Baffin Island segment of the orogen is first presented, followed by its tectonic architecture, deformation and metamorphic events, and finally, the Frobisher suite sills and their Lake Harbour Group host rocks. !viii D.A. Liikane, M.Sc. thesis Chapter 4 – Overview of the methods used in completing the thesis, including sample collection and processing, and analytical methods. Chapter 5 – Detailed petrography of the Frobisher suite sills, where mineral assemblages and textures are described. Chapter 6 – Mineral chemistry of the Frobisher suite sills. Chapter 7 – Detailed geochemical study of the Frobisher suite sills, where eight geochemical groups are recognized and described individually, with some comparison between groups. Chapter 8 – Discussion of the general characteristics and petrogenesis of each geochemical group, the petrogenesis and models for the formation of the two mafic-ultramafic sills sampled in detail, the candidacy for the Frobisher suite being considered a LIP, evidence for mantle plume-involvement versus passive rift magmatism, post-emplacement modification, regional implications, a model of formation for the Frobisher suite, and its metallogenic potential. This is followed by the summary of the main conclusions of the study, and future considerations. Appendices: Appendix A contains sample coordinates, Appendix B contains field and petrographic data (Chapter 5), Appendix C contains bulk-rock geochemical data (Chapter 7), Appendix D contains mineral geochemical data (Chapter 6), and Appendix E contains Sm-Nd isotopic data (Chapter 7). !ix D.A. Liikane, M.Sc. thesis Table of Contents Frontispiece ....................................................................................................................iii Abstract...........................................................................................................................iv Acknowledgements.........................................................................................................v Method of Presentation................................................................................................viii Table of Contents.............................................................................................................x List of Appendices......................................................................................................xviii