Churchill Craton

The Churchill Craton is the northwest section of the Canadian Shield and stretches from southern Saskatchewan and Alberta to northern Nunavut. It has a very complex geological history punctuated by at least seven distinct regional tectonometamorphic intervals, including many discrete accretionary magmatic events. The Western Churchill province is the part of the Churchill Craton that is exposed north and west of the Hudson Bay. The Archean (ca. 1.83 Ga) Western Churchill province contributes to the complicated and protracted tectonic history of the craton, and marks a major change in the behaviour of the Churchill Craton with many remnants of Archean supracrustal and granitoid rocks.

A north-northwest-trending crustal segment transects from Kaminak Lake (central Hearne Domain) in the south to Yathkyed Lake (northern Hearne Domain) in the northwest, consisting of Archaen supracrustal belts that preserve mostly Archean mafic to felsic volcanic rocks (greenschist-grade supracrustal and granitoids), metamorphic cooling of hornblende and Proterozoic biotite.

This section of the Churchill province was formerly called the Ennadai-Rankin greenstone belt and include the Kaminak, Yathkyed, MacQuoid and Rankin supracrustal belts, containing a wide range of intrusive Neoarchean plutonic rocks ranging in composition from gabbro to syenogranite. The Kaminak supracrustal belt preserves igneous textures including interlocking quartz and plagioclase that are intergrown with platy biotite (2.084-1.914 Ga) and stubby euhedral grains of prismatic titanite and hornblende. The Yathkyed belt contains a range of hornblende cooling (2.63-246 Ga) amphibolitic metamorphic rocks. The Kaminak and Yathkyed belts are overlain by the Proterozoic (2.45 Ga) Hurwitz Group. Deformation of the Hurwitz Group occurred after the 2.11 Ga intrusion of gabbro sills, but prior to the intrusion of the 1.83 Ga lamprophyre dykes associated with the ultrapotassic lavas of the nearby Baker Lake Basin. Parallel to the Paleoproterozoic Hurwitz Group are massive veins of green biotite that are interpreted to have been emplaced there by a hydrothermal event accompanying a deformation along this contact area.

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