SUBPROVINCE ACCRETION TECTONICS IN THE SOUTH-CENTRAL SUPERIOR PROVINCE

Development of tectonic subprovinces as shear-bounded granite-greenstone and sediment-dominated terranes during the late Archaean is reviewed and interpreted from relationships between portions of the Wabigoon, Wawa, and Quetico subprovinces. Sediment-dominated subprovinces (Quetico) are metamorphosed wacke sequences deposited during and after the volcanic climax in the period 2.70-2.69Ga. Abukuma-style metamorphism, migmatite formation, and S-type granite intrusions occurred during the period 2.67-2.65Ga. Greenstone-belt developments, terminated during large-scale (100-1000km) late neo-Archaean accretion, are preserved within elongate, batholith-dominated terranes separated by metasedimentary migmatite belts. Geochronological, lithotectonic, and metamorphic patterns on a scale of hundreds of kilometres are permissive of an accretionary model of greenstone terrane coalescence in which formation of long-lived, complex volcanic arcs and a complementary fore-arc accretionary prism culminated in large-scale accretion and the formation of stable continental crust. -from Author