Paleoproterozoic tectonic assembly of Northeast Laurentia through multiple indentations

摘要: Recent detailed geological mapping and UPb geochronological studies in the Torngat, Ungava Baffin orogens of Northeast Laurentia have provided new information regarding tectonic assembly this region between ∼1.92 1.74 Ga. In contrast with an earlier hypothesis whereby geometry Archean continental fragments was thought to resulted entirely from northerly indentation Superior Province consequent extrusion tectonics, interpretation recently acquired data shows that last multiple collisional events during formation Laurentia. In present model, we propose Southeast Rae North provinces were separate prior Ga, when regional tectonism changed extension contraction. Westerly subduction westward translation Disko terrane Nain development a magmatic arc Cumberland batholithic complex Torngat orogen, deposition upper sequences Penrhyn-Piling-Karrat Foxe Rinkian belts orogen (1880–1895 Ma). Continental collision produced shortening across at, or before, 1876 Ma. Meanwhile, early magmatism (1861–1898 Ma) accompanied foredeep transtensional basin New Quebec (∼1870–1883 onset deformation southeastern Nagssugtoqidian (∼1883 Ma). Nain-Southeast at ∼1860 Ma caused renewed granitic metamorphism 1857 1853 Initiation felsic volcanism Makkovik-Ketilidian time indicates shift locus plate southern margin Province. southerly resulting generation second suite 1844 1826 Formation de Pas batholith hinterland ∼1840 arc-continent Superior-Southeast 1845 1829 At time, accretion material contemporaneous high-grade sinistral shearing along reactivated northwestern orogen. Southeast-directed thrusting complex, reactivation belt is predicted also occurred time. At ⩽1826 Ma, initiated closure Rae-Southeast juncture Ford Lake plutonic suite. Subsequent (∼1810 dextral “escape tectonics” belts, thick-skinned folding basement cover High-grade granitoid occurred. Reactivation Nain-Southeast (east-directed thrusting) (west-directed margins ∼1790 “pop-up” its more rigid neighbors. Final cooling emplacement post-tectonic rocks took place ∼ 1740–1790