Circa 2.3-Ga Magmatism of the Arrowsmith Orogeny,Uranium City Region,Western Churchill Craton,Canada

摘要

The western margin of the Churchill craton records a complex history of Paleoproterozoic tectonism.The most prominent of these tectonic events is recorded within the 2.0-1.9-Ga Taltson-Thelon magmatic zone.The widespread magmatism and high-grade metamorphism of this zone,especially in Alberta and Saskatchewan,obscures an older tectonic belt,the ca.2.4-2.3-Ga Arrowsmith Orogeny.In the Uranium City region of northwestern Saskatchewan,a suite of Paleoproterozoic granites represent a magmatic product of this orogen.U-Pb zircon crystallization ages were identified for the Macintosh Bay monzogranite(2330 ± 5 Ma),the Gunnar monzogranite(2321 ± 3 Ma),the Geebee Lake tonalite(2320 ± 44 Ma),the Yahyah Lake granite(2287 ±14 Ma),and the Hayter Bay monzogranite(2297 ± 10 Ma).The petrological and geochemical characteristics,emplacement ages,and Nd isotopic geochemistry of these plutons are most consistent with a syn-to postcollisional orogenic setting,possibly coeval with a period of orogenic extension and exhumation.