Three distinct stratigraphic units have been recognized in the Crow Lake – Savant Lake belt. These are a basal unit consisting of high magnesium tholeiitic flows, a middle unit consisting mostly of tholeiitic to calc-alkaline pyroclastic rocks and flows, and an upper unit of high iron tholeiitic flows.A zircon U–Pb study has been carried out on seven rocks from the Wabigoon–Manitou Lakes region of this belt. In the Manitou Lakes area, a minimum age of 2755 Ma on a porphyry pluton intruded into the Wapageisi Volcanics gives a minimum age for the high magnesium tholeiitic sequence.A trondhjemite phase of the Atikwa batholith near Wabigoon Lake that is dated at 2732.2 ± 2.9 Ma has the same age within experimental error as a rhyolite flow from the Lower Wabigoon Volcanics in the same area that is dated at [Formula: see text]. However, a trondhjemite phase of the Atikwa batholith at Eagle Lake that is dated at [Formula: see text] is distinctly younger than a dacite flow collected nearby from the Lower Wabigoon Volcanics that is dated at [Formula: see text]. Both these volcanic rocks are from the middle mixed sequence.A rhyolite tuff from the Boyer Lake Volcanics, from the upper high iron tholeiitic sequence, gives a relatively young age of [Formula: see text]. An age of 2695 ± 3.6 Ma on the post-tectonic Taylor Lake stock gives a minimum age for the end of deformation.Several new techniques such as air abrasion with pyrite, crushing and abrasion, and high gradient magnetic separation have been employed to reduce the discordance of zircons. Of these, the air abrasion technique has proven to be the most effective.
The Archean volcanic rocks in the Cameron–Rowan lakes area may be divided into three distinct successions based on field mapping, petrographic studies, and lithogeochemical characteristics. The lowermost Rowan Lake Volcanics are tholeiitic pillowed basalts. These rocks are unconformably overlain by the Cameron Lake Volcanics, a mixed succession of tholeiitic massive and pillowed basalts and intermediate to felsic volcaniclastic rocks. The Brooks Lake Volcanics consist of tholeiitic basalts and represent the youngest volcanic rocks at the top of the preserved succession.Most of the gold concentrations in the Cameron–Rowan lakes area are confined to the mixed Cameron Lake Volcanics. The majority of these, including the Cameron Lake deposit, occur within shear zones near lithologic contacts. In the Eagle–Wabigoon and Manitou lakes areas there are similar stratigraphic subdivisions of the supracrustal rocks and many of the gold concentrations also occur in deformation zones within the mixed volcanic successions. The contrasting competencies among the basalts, the intermediate to felsic volcaniclastic rocks, and the intrusive rocks, which are characteristic of the mixed volcanic successions, localized stress during deformation, forming shear zones into which gold-bearing fluids gained access. The potential for successfully delineating economic gold concentrations appears greatest in the mixed volcanic successions within these areas and elsewhere in the western Wabigoon Subprovince of the Canadian Shield.
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