The geology of the zinc-lead deposit at Sito Lake, northern Saskatchewan
Harper, Charles T.
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The Sito West deposit at Sito Lake is one of a number of uneconomic disseminated zinc-lead and lead-zinc-quartzite deposits that have been located within the Wollaston Lake fold-belt of northern Saskatchewan. Metasedimentary rocks belong to the Daly Lake Group which is most widespread, and the Meyers Lake Group which contains the quartzite host of the sulphides. The Meyers Lake Group apparently overlies the Daly Lake Group here. Graded beds preserved in the Meyers Lake Group commonly show compositional gradation from basal arkose to shaly tops. Metamorphism has produced garnet-biotite-rich and sillimanite augen-biotitegarnet-rich portions near the tops of these beds. It is proposed that they indicate deposition by turbidity currents. Three major phases of deformation produced a series of elongate, steeply inclined basins and domes. The domal structure at Sito West is like the central conical portion of an "angel-food cake-pan " if it were flattened and inclined. Metamorphic mineral assemblages are characteristic of Abukuma-type cordierite-amphibolite facies and lower granulite facies metamorphism. The mineralization, which occurs in the upper half of the quartzite unit, consists essentially of dissiminated pyrite sphalerite, and galena. The sulphides precipitated during deposition of the host, but diagenesis and metamorphism has destroyed textural evidence. The deposits are similar to the copper-uranium-vanadium-sanstone deposits of the southwestern United States.