Abstract

Three U–Pb zircon and four K–Ar mineral age determinations from national topographic system (NTS) area Geikie River (SE) in northern Saskatchewan are presented and the geology of the region is described. The area lies within the Churchill Province of the Canadian Precambrian Shield and includes parts of the Wollaston, Peter Lake, and Rottenstone domains; the relationship between the geological histories of these domains and the age determinations is discussed. Zircon age measurements suggest a period of late Archean magmatism ca. 2500 Ma was responsible for both the Wollaston domain granitic basement and a suite of basic plutons in the adjoining Peter Lake domain.The overall lithological differences of the presumed lower Proterozoic supracrustal rocks in the region are examined in the context of a plate tectonic model. This invokes late Archean continental rifting accompanied by limited volcanism close to the present Needle Falls Shear Zone, followed by continental separation and the generation of an Aphebian ocean basin. Deposition of shelf and deeper water sediments along the trailing edge of the Wollaston domain continental margin was followed by reversal of plate movement, oceanic subduction, and the formation of an island-arc complex. This marked the start of the Hudsonian Orogeny and was accompanied by the development of successive generations of granitic material, including the Wathaman batholith. The regional emplacement of this batholith ca. 1865 Ma ago is compared to other volcano-plutonic belts described elsewhere along Cordilleran-type continental margins.

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