Anton terrane revisited: Late Archean exhumation of a moderate-pressure granulite terrane in the western Slave Province

The Anton terrane of the western Slave Province has been interpreted as a r emnant of a meso-Archean (3500-2800 Ma) microcontinent. The largest coheren t entity of the terrane is a previously unrecognized 50 by 250 km granulite complex, herein termed the Snare domain. The granulite facies mineral asse mblages give the domain a characteristic magnetic signature that is distinc t from areas of exposed meso-Archean basement in the Slave Province. The do main consists of interlayered 3100-2624 Ma orthogneisses and paragneisses a nd 2600-2585 Ma granitoid rocks; its structure was largely established duri ng 2610-2590 Ma orogeny throughout the province that culminated in ca. 2590 Ma granulite facies metamorphism. Pressure-temperature (P-T) determination s yield peak conditions of 775-875 degreesC at 6-7 kbar. Shortly thereafter , 2-4 kbar of decompression occurred before the domain cooled below 450 deg reesC. Decompression and retrogression textures are widespread but are most pervasive adjacent to late extensional detachment faults. U-Pb zircon age data suggest that the Snare domain was partially exhumed from mid-crustal l evels ca. 2585-2580 Ma. We attribute exhumation to tectonic denudation of a n overthickened crustal welt in the western Slave Province. Localization of the crustal welt in this part of the Slave Province may be related to the presence there of meso-Archean crust.