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University of Calgary PRISM: University of Calgary's Digital Repository Graduate Studies The Vault: Electronic Theses and Dissertations 2013-04-30 Cenozoic Cooling Patterns from the Canadian Cordillera using the Uranium-Thorium-Helium Method Bacque, David Bacque, D. (2013). Cenozoic Cooling Patterns from the Canadian Cordillera using the Uranium-Thorium-Helium Method (Unpublished master's thesis). University of Calgary, Calgary, AB. doi:10.11575/PRISM/25240 http://hdl.handle.net/11023/663 master thesis University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission. Downloaded from PRISM: https://prism.ucalgary.ca UNIVERSITY OF CALGARY Cenozoic Cooling Patterns from the Canadian Cordillera using the Uranium-Thorium-Helium Method by David Pierre Bacque A THESIS SUBMITTED TO THE FACULTY OF GRADUATE STUDIES IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE DEPARTMENT OF GEOSCIENCE CALGARY, ALBERTA APRIL, 2013 © David Pierre Bacque 2013 Abstract The Cenozoic cooling history of the Canadian Cordillera is important for understanding large- scale processes and relative importance of smaller geologic features. Our study uses the uranium- thorium-helium method, which provides a cooling history for upper crust (~2-6 km). Our data helps resolve near surface problems such as the amount and extent of overburden removed during the Cenozoic, the possible mechanisms to explain the loss of the thick overburden (i.e. tectonic, climate, erosion), and how our regional cooling history fits into the cooling histories we already have for the Cordillera. Using our data we estimated the amount of overburden removed from the Foreland Belt portion of our study, since the L. Paleocene, to be 5-9 km and did extend further west into the Cordillera. Using hanging wall and footwall relationships, we found that faulting, despite lying in the extensional regime in the current model did not control cooling. ii Acknowledgements I would like to acknowledge my Supervisor, Dr. Bernard Guest, for giving me the opportunity to work on this project. I would also like to acknowledge Dr. Edward Ghent and William Mathews for the mentorship and advice during my thesis. Finally, I would like to acknowledge Daniel Stockli for allowing me to use his lab. iii Table of Contents Abstract ............................................................................................................................... ii Acknowledgements ............................................................................................................ iii Table of Contents ............................................................................................................... iv List of Figures ................................................................................................................... vii CHAPTER 1: INTRODUCTION ........................................................................................9 1.1 Questions to be addressed ........................................................................................10 1.2 Regional geology .....................................................................................................12 1.3 Previous thermochronological work ........................................................................15 Southern Foreland Belt .............................................................................................15 Southern Omineca Belt .............................................................................................15 Southern Intermontane Belt ......................................................................................17 CHAPTER 2: LOCAL GEOLOGY ...................................................................................18 2.1 Whistlers Mountain ..................................................................................................18 2.2 Ptarmigan Mountain ................................................................................................19 2.3 Raft Mountain ..........................................................................................................22 2.4 Nicola Horst .............................................................................................................22 CHAPTER 3: METHODS .................................................................................................30 3.1 Sampling methods ....................................................................................................30 3.2 Mineral separation methods .....................................................................................31 3.4 Grain selection .........................................................................................................32 3.5 The uranium-thorium-helium method .....................................................................33 3.6 Lab analysis .............................................................................................................36 3.7 Alpha ejection correction (FT) .................................................................................37 CHAPTER 4: RESULTS ...................................................................................................39 4.1 Whistlers Mountain ................................................................................................40 NM1-37-01 ...............................................................................................................40 NM1-37-02 ...............................................................................................................41 NM1-37-03 ...............................................................................................................41 NM1-37-04 ...............................................................................................................42 NM1-38-05 ...............................................................................................................43 NM1-39-06 ...............................................................................................................43 NM1-39-07 ...............................................................................................................44 NM1-39-08 ...............................................................................................................45 Interpretation of Whistlers Mountain .......................................................................45 4.2 Ptarmigan Mountain ................................................................................................48 AH47-1 .....................................................................................................................48 AH48-1 .....................................................................................................................48 AH48-2 .....................................................................................................................49 AH49-3 .....................................................................................................................49 AH49-1 .....................................................................................................................50 iv AH49-2 .....................................................................................................................50 Interpretation of Ptarmigan Mountain ......................................................................51 4.3 Raft Mountain ..........................................................................................................53 DB-1-1-1 ...................................................................................................................53 DB-1-1-2 ...................................................................................................................53 DB-1-4-1 ...................................................................................................................54 DB-1-3-1 ...................................................................................................................54 Interpretation of Raft Mountain ................................................................................55 DB-1-5-1 ...................................................................................................................55 DB-1-5-2 ...................................................................................................................56 DB-1-6-1 ...................................................................................................................56 DB-1-15-1 .................................................................................................................58 DB-1-13-1 .................................................................................................................58 DB-1-7-2 ...................................................................................................................58 DB-1-8-1 ...................................................................................................................59 DB-1-9-1 ...................................................................................................................59 DB-1-10-1 .................................................................................................................60