Convergent margin tectonics, central Wabigoon subprovince, Superior Province, Canada

Best known for its Neoarchean greenstone-granite terranes in the east and west, the Wabigoon subprovince of the Superior Province features a central transverse corridor of Meso- and Neoarchean gneissic, granitoid, and minor supracrustal rocks resembling an eroded intermontane plateau. Structural analysis and U–Pb geochronology in the north-central Wabigoon subprovince reveal a complex history of plutonism, supracrustal rock deposition, polyphase deformation and amphibolite-facies metamorphism between 3075 and 2670 Ma. The geometric and kinematic character of D1 and D2 deformational events recorded in 2890–2718 Ma tonalitic gneisses remain cryptic as a result of magmatic and structural (D3–5) overprinting, but the early structures are bracketed in age between 2725 and 2713 Ma by a polydeformed gneiss and tonalite dyke. These events occurred deep within an active continental magmatic arc and correspond in age to a collision between the juvenile Wabigoon and continental Winnipeg River subprovinces recognized to the west. c sediments deposited after 2701 Ma are the youngest rocks involved in subsequent regional deformation. A D3 event is responsible for rapid burial of supracrustal units to 15 km within warm arc crust, and imposition of a regional, penetrative, S3 foliation that accommodated some relative uplift prior to 2697 Ma, the age of a discordant granodiorite dyke. This event corresponds to variably preserved, steep, north-trending D1 structures recognized in adjacent greenstone belts. uent (D4) ductile deformation defines the map pattern in the deep crustal rocks of the central Wabigoon subprovince. Upright, east-trending F4 folds developed synchronously with D2 dextral transpressive structures that formed throughout the Wabigoon subprovince prior to 2698 Ma. The final (D5) sinistral shearing event occurred during emplacement of mantle-derived granodiorites of sanukitoid affinity (2688 Ma) and crust-derived granites (2685 Ma). This event appears to have triggered rapid cooling, reflected in 2680–2670 Ma titanite dates and late brittle increments of displacement.