Geological evolution of the Manitouwadge greenstone belt and Wawa-Quetico subprovince boundary, Superior Province, Ontario, constrained by U-Pb zircon dates of supracrustal and plutonic rocks

Fifty million years of Archean evolution is recorded in the Manitouwadge gr eenstone belt and the Wawa-Quetico boundary region, from ca. 2720 Ma volcan ism and subvolcanic plutonism associated with massive sulphide deposits and hydrothermal alteration zones, to 2689-2687 Ma and 2680-2677 Ma synkinemat ic plutonism. In the greenstone belt, greywackes were deposited after 2693 Ma, post-dating local volcanism by at least 25 Ma, and requiring that the v olcanic-sedimentary contact is an unconformity or a fault. In migmatitic gr eywackes in the Quetico subprovince, detrital zircons limit the depositiona l age to <.2690 Ma, permitting correlation of greywackes across the Wawa-Qu etico subprovince boundary. Upward-facing inclined F-2 folds that deform th e volcanic-sedimentary contact are bracketed by the 2687 +/- 2 Ma Loken Lak e pluton, which shows strong Da fabrics, and by 2680(-3)(+4) Ma foliated gr anite which cuts D-2 fabrics. Dextral transpression producing regional F-3 folds and the overall east-west trends of the Wawa-Quetico boundary region post-dated the 2680 +/- 2 Ma Nama Creek pluton. Field relationships and iso topic ages support correlation of greywackes across the subprovince boundar y, and demonstrate that most or all of the ductile deformation post-dated s edimentation. Ductile structures, especially those associated with dextral transpression, are not directly related to juxtaposition of the Wawa and Qu etico subprovinces, as these were already contiguous, either through sedime ntation on a volcanic substrate or as a result of earlier cryptic structure s. Our results imply that the belt-like configuration of the subprovinces, emphasized in accretionary models of the Superior Province, is a relatively late feature that overprints older, tectonically significant structures.