Precambrian geology of Boothia Peninsula, Somerset Island and Prince of Wales Island, district of Franklin

Boothia Peninsula and we tern Somerset Island are dominated by the Boothia Arch, a structural and topographic high composed of Precambrian igneous and metamorphic rocks. Relatively fiat-lying unfossiliferous sedimentary strata overlie the northernmost exposures of Boothia Arch, and they are in turn overlain by lower Palaeozoic sedimentary rocks. All pre-Palaeozoic rocks are cut by gabbro dykes and sill s. These are most abundant in western Somerset Island. Potassium-argon age determinations made on biotite indicate an Aphebian (early Proterozoic) age for the la test metamorphism of the gneissic complex. The results of modal analyses and 82 'rap id method' chemical analyses accompany the descriptions of the gneissic and igneous rocks.