Volume 16, Number 3 (1989)
Articles

Geochemical constraints on the origin of mafic rocks from the Cape Smith Belt

E. Hegner
ithosphère and Canadian Shield Division, Geological Survey of Canada, Ottawa, Ontario.
M. L. Bevier
Lithosphère and Canadian Shield Division, Geological Survey of Canada, Ottawa, Ontario.
Published September 9, 1989
How to Cite
Hegner, E., & Bevier, M. L. (1989). Geochemical constraints on the origin of mafic rocks from the Cape Smith Belt. Geoscience Canada, 16(3). Retrieved from https://journals.lib.unb.ca/index.php/GC/article/view/3615

Abstract

The Trans-Hudson Orogen in Canada represents an early Proterozoic mountain belt similar to Phanerozoic orogens formed by plate tectonic processes. Volcanic rocks in northern Manitoba and Saskatchewan resemble island arc terranes, while continental rift and oceanic volcanic rocks dominate in the Cape Smith Belt in northern Quebec. Pb-Pb whole rock isotopic data for the ophiolitic Watts Group of the Cape Smith Belt yield an age of 1980 ± 30 Ma. Pb-Pb metamorphic (?) ages of 1890 Ma and 1700 Ma were determined for rift-related igneous rocks of the Povungnituk Group and transitional volcanic rocks of the Chukotat Group, respectively. Sm-Nd isotopic compositions are consistent with a magmatic evolution characterized by involvement of lithospheric mantle in Povungnituk Group volcanism, and depleted asthenospheric magma sources for MORB-like Chukotat Groupbasalts Sm-Nd isotopic compositions of the Watts Group show the characteristics of both Povungnituk and Chukotat Group basalts, suggesting similar sources.