U-Pb geochronology of deformation and metamorphism across a central transect of the early Proterozoic Torngat Orogen, North River map area, Labrador

The Early Proterozoic Torngat Orogen resulted from the oblique collision of the Archean Nain and southeastern Rae provinces and evolved in four stages: (1) deposition of platformal supracrustal assemblages followed by subduction-related arc magmatism in the margin of the Rae Province; (I) crustal thickening and nappe tectonics; (II) sinistral transpression and formation of the Abloviak shear zone; (III) uplift on steeply dipping, east-verging mylonites along the eastern orogenic front. U-Pb geochronology on zircon and monazite from major rock units and syntectonic intrusions indicates that arc magmatism at ca. 1880 Ma was followed by 40 Ma. of deformation and high-grade metamorphism from ca. 1860 to 1820. Subsequent uplift and final cooling occurred ca. 1795-1770 Ma. Several ages of mineral growth that correspond to distinct structural and metamorphic events have been recognized. -from Authors