Abstract

Plate-tectonic models of the Superior province are rooted in the granite-greenstone and metasedimentary belts of the southern part of the craton. North-striking domains of the Minto block in the northeastern part of the province evolved at similar times, in 3.1-2.8, 2.725, and 2.69 Ga events, requiring expansion of models of late Archean assembly to accommodate Minto geology. Western and eastern protocratons (∼3.1-2.8 Ga) rifted at ∼2.79 Ga to produce an ocean basin that was mostly consumed by subduction at 2.725 Ga. The Leaf River plutonic suite of cale-alkalic hornblende + biotite ± orthopyroxene ±clinopyroxene granodiorite represents magmatic arcs built on the protocratons, whereas the intervening Goudalie domain—containing fault-bounded fragments of rifted continental crust, rift volcanics, primitive oceanic crust, 2724 Ma island-arc rocks, and a <2718 Ma back-arc assemblage—marks the suture. Terminal collision at ∼2.7 Ga led to thickening and crustally derived granitoid magmatism. The southern Superior province also experienced vigorous activity between 2.725 and 2.69 Ga as island arcs, oceanic plateaus, continental fragments, and accretionary prisms were amalgamated progressively from north to south in a regime of dextral transpression then stitched by granites. A northern proto-Superior craton had continental magmatic arcs built on its eastern and southern flanks in response to west-northwest-directed subduction; orthogonal convergence in the east produced wide plutonic arcs, in contrast to terrane-accretion tectonics in the more oblique regime along the southern margin.

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