U–Pb zircon geochronology of the Kapuskasing structural zone and vicinity in the Chapleau–Foleyet area, Ontario
Geological development of the Archean Abitibi and Wawa greenstone–granite subprovinces of the Superior Province occurred in three main stages: (1) a volcanic–sedimentary depositional stage ~2750–2696 Ma ago, (2) a metamorphic–tectonic event ~2700–2685 Ma ago, and (3) a late plutonic event at ~2685–2668 Ma. The area between Wawa in the west and Ivanhoe Lake in the east represents an oblique section through some 20 km of the crust, where geochronological relationships can be examined at different structural levels. Much of the eastern Wawa Subprovince is characterized by tonalite–granodiorite gneiss containing abundant mafic xenoliths and represents a crustal level intermediate between high-level metavolcanic rocks near Lake Superior and the deep-seated gneisses of the Kapuskasing structural zone. A tonalitic phase of the complex gneiss of the Wawa Subprovince has a minimum U–Pb zircon date of 2707 Ma but the fine zircons are partly reset, possibly in response to lit-par-lit injections of gneissic to foliat...