The geology of the Collins Bay uranium deposit, Saskatchewan

CIM Bulletin, Vol. 73, No. 818, 1980

B.E. JONES, Senior Staff Geologist-Uranium, Gulf Minerals Canada Limited, Saskatoon, Saskatchewan

The area of uranium deposition is situated within the Churchill Province on the western edge of the Wollaston lithostructural domain where it underlies the eastern edge of the Helikian Athabasca Formation. The Collins Bay deposit is 6 miles north-northeast of the Rabbit Lake mine. Two principal zones of uranium mineralization are described.The "A " zone is a partly eroded, high-grade pod of metal oxide and arsenides sheathed by clay-like minerals. It trends north-northeast and lies under 25 to 40 feet of water. Uranium mineralization is localized at or adjacent to the unconformity between the Athabasca Formation and the basement rocks. The basement comprises a granitoid Archean terrain overlain by paragneisses of the Aphebian Wollaston Group. "A" zone ore contains phyllosilicates, quartz, pitchblende, ram-melsbergite, pararammelsbergite, carbonaceous material, galena, gersdorffite, niccolite, carbonate and a trace of sphalerite.The "B" zone lies 6,000ft south of the "A ", andsubcrops under till cover. It is a partly eroded zone composed of metal oxide and arsenides which occur within variably altered A thabasca Formation. Minerals recognized are phyllosilicates, pitchblende, niccolite, gersdorffite, millerite, carbonaceous material, pyrrhotite, skutterudite and a trace of galena. The Athabasca Formation varies from 90 to 160ft thick. Granitoid gneisses of probable Archean age and paragneisses of the Wollaston Group underlie the deposit. An easterly dipping thrust fault transects its length.The deposit is typical of the "unconformity-type" uranium-nickel deposits of the Athabasca Basin. Observed features fit well with the "diagenetic-hydrothermal" model for such deposits, as envisioned by Hoeve and Sibbald (1978).

Mots Clés: Uranium, Collins Bay deposit, Saskatchewan, Geology, Mineralization, Paragenesis, Nickel, Athabaska Formation.