Proterozoic evolution of the Northern Thelon Tectonic Zone

The Northern Thelon Tectonic Zone represents the locus of Proterozoic oblique convergence between the Archean Slave and Churchill Provinces of the Northwestern Canadian shield. Dextral strike - slip movement is manifest in ductile reorientation of the exposed lower crust up to 15 km from the Thelon Front, is preserved in deformed sediments of the Goulburn Supergroup to the west. The occurrence of these two components invites comparison with present day transpressive boundaries characterized by mid-crustal detachment.;The Thelon Front is characterized by a discontinuity in lithology, metamorphic grade, and structure and, at least in the Ragged Lake area, marks the ramp of a major crustal-scale, west verging, thrust system. The boundary has been extensively modified by late stage deformation, and retrograde metamorphism during uplift.;Within the upper thrust system (hangingwall), granulite grade garnet - plagioclase - pyroxene, and garnet - cordierite - hercynite - sillimanite - biotite corona assemblages, intruded by charnockite, record a clockwise P-T path and penetrative high strain while partially molten. The maximum P and T recorded is 8854 ;Amphibole and biotite...