Abstract

The North Shore Plutons are peraluminous granitoids emplaced within the Murmac Bay Group supracrustals exposed on the north shore of Lake Athabasca, Saskatchewan. 207Pb/206Pb ages obtained using the single-zircon Pb-evaporation technique indicate emplacement at 1952 ± 18 Ma, coeval with Taltson magmatism that occurred during the 1.9–2.0 Ga Thelon orogeny, which influenced the Rae Province. The granitoids inherited zircons from Archean source terranes dated at approximately 2.5 and 3.0 Ga. Detrital zircons from the younger source terrane were also identified in the Murmac Bay Group, thus constraining the maximum age of the group to the Paleoproterozoic.Rare earth element and incompatible element data and Rb–Sr and Sm–Nd isotope systematics from the North Shore Plutons and adjacent host rocks indicate that the plutons are crustal melts generated from melting of Murmac Bay Group rocks and Archean crust at deeper levels. Granitic gneisses described as "Older" Granites represent mixtures of variable amounts of magmatic fluids similar to those that formed the North Shore plutons and the Murmac Bay Group metasedimentary rocks.

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