Structural, geochronological, and metamorphic characterization of the Monashee décollement and its role in the tectonic evolution of the Canadian Cordillera
department or school: Science, Irving K. Barber Faculty of (Okanagan)
department or school: Earth, Environmental and Geographic Sciences, Department of (Okanagan)
data provider: DSpace
degree campus: UBCO
creator: Holt, Katharina
issued: 2022-05-04T23:52:03Z
issued: 2022
related degree: Master of Science - MSc
degree grantor: University of British Columbia
description: The Monashee décollement (MD) is a crustal-scale shear zone within the southern Omineca belt of the Canadian Cordillera. The MD marks the contact between the autochthonous Precambrian basement core rocks of the Monashee metamorphic complex and the allochthonous rocks of the Lower Selkirk Allochthon. Both packages were metamorphosed at mid-crustal depths (>20 km) but are now exposed at ~ 2200 m elevation. The timing and style of deformation along the MD are disputed. Studies have proposed that the MD is: 1) the base of a mid-crustal ductile “channel”; 2) a complex normal-sense (top-to-the-west) extensional shear zone; or 3) a major reverse-sense (top-to-the-east) contractional shear zone that possibly forms the basal detachment of the Rocky Mountain thrust and fold belt. This study was conducted to investigate those different interpretations through characterizing the detailed temperature-time deformation histories of the rocks within and adjacent to the MD at the Probity Peak field site, ~ 50 km northwest of Revelstoke, British Columbia. This was achieved through: 1) geological field mapping; 2) microstructural analyses of oriented thin sections; 3) quartz c-axis crystallographic preferred orientation (CPO) investigation and opening angle geothermometry; 4) titanium-in-biotite (Ti-in-Bt) geothermometry; and 5) titanite and monazite petrochronology. The data acquired from this study, combined with that from published literature indicate that the MD was active as a reverse-sense contractional shear zone at Probity Peak between ca. 85-80 and 70-65 Ma. The MD was then crosscut by high-angle, brittle-ductile normal faults during extension between ca. 60 and 49 Ma. This extension facilitated exhumation of the Monashee Complex, which continued through Eocene time.
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/81469
note: STRUCTURAL, GEOCHRONOLOGICAL, AND METAMORPHIC CHARACTERIZATION OF THE MONASHEE DÉCOLLEMENT AND ITS ROLE IN THE TECTONIC EVOLUTION OF THE CANADIAN CORDILLERA by Katharina Holt BASc, Queen’s University, 2019 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE COLLEGE OF GRADUATE STUDIES (Earth and Environmental Sciences) THE UNIVERSITY OF BRITISH COLUMBIA (Okanagan) May 2022 © Katharina Holt, 2022 ii The following individuals certify that they have read, and recommend to the College of Graduate Studies for acceptance, a thesis / dissertation entitled: Structural, geochronological, and metamorphic characterization of the Monashee décollement and its role in the tectonic evolution of the Canadian Cordillera submitted by Katharina Holt in partial fulfillment of the requirements of the degree of Master of Science Dr. Kyle Larson, Irving K. Barber Faculty of Science – Department of EEGS Supervisor Dr. John Greenough, Irving K. Barber Faculty of Science – Department of EEGS Supervisory Committee Member Dr. Dawn Kellett, Geological Survey of Canada Supervisory Committee Member Dr. David Jack, Irving K. Barber Faculty of Science – Department of Chemistry University Examiner iii Abstract The Monashee décollement (MD) is a crustal-scale shear zone within the southern Omineca belt of the Canadian Cordillera. The MD marks the contact between the autochthonous Precambrian basement core rocks of the Monashee metamorphic complex and the allochthonous rocks of the Lower Selkirk Allochthon. Both packages were metamorphosed at mid-crustal depths (>20 km) but are now exposed at ~ 2200 m elevation. The timing and style of deformation along the MD are disputed. Studies have proposed that the MD is: 1) the base of a mid-crustal ductile “channel”; 2) a complex normal-sense (top-to-the-west) extensional shear zone; or 3) a major reverse-sense (top-to-the-east) contractional shear zone that possibly forms the basal detachment of the Rocky M…
has type: Thesis/Dissertation
date issued: 2022-05
is shown at: 10.14288/1.0413222
language: eng
degree discipline: Earth and Environmental Sciences
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivatives 4.0 International
rights URI: http://creativecommons.org/licenses/by-nc-nd/4.0/
scholar level: Graduate
contributor: Larson, Kyle P.
type: Text
identifier URI: http://hdl.handle.net/2429/81469