The Shuswap Metamorphic Complex (SMC) in southeastern British Columbia exposes penetratively deformed rocks exhumed from the deepest structural levels of the Canadian Cordillera. U-Th-Pb monazite petrochronology, metamorphic phase modelling and microstructural analysis are used to quantify Pressure-Temperature-time-deformation (P-T-t-d) constraints on deep orogenic processes and the activity of ductile shear zones bounding the SMC. Dates obtained from monazite chemical domains, correlated with metamorphic and deformational fabric-forming events, suggest that peak metamorphic conditions young with increased structural depth, and reflect a progressive localization of opposite-sense shearing towards the top and bottom margins of the SMC over time. Protracted northeast-directed compression occurred from ~165–58 Ma, after which west-directed ductile extension continued until at least ca. 47 Ma. P-T-t-d paths are consistent with basal accretion in front of a foreland-propagating ductile thrust system, followed by exhumation via normal faulting – similar to models proposed for other collisional systems such as the Himalayan orogen.
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Thesis advisor: Gibson, H. Daniel
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