Geology and geochemistry
\nof the Fenton Creek Zone (Manitoba, Canada)

The Fenton Creek deposit is a new Zn-Cu base metal discovery situated 70km southeast
\nof the town of Snow Lake, which hosts numerous polymetallic Zn-Cu and Cu-Zn volcanic hosted
\nmassive sulphide (VHMS) deposits. The Fenton Creek deposit was located using airborne EM
\nand MAG techniques and is completely blind with no surface expression as it is overlain by 30m
\nof Paleozoic limestone and dolomite and 20m of muskeg. Diamond drilling has defined an initial
\ngeologic resource of 2.3 Mt grading 0.09g/t Au, 20.42g/t Ag, 0.56% Cu and 7.44%Zn.
\nThe deposit consists of two massive sulphide lenses hosted within a mixed sequence of
\ngraphitic metasediment and volcaniclastics. Amphibolite grade metamorphism has destroyed
\nmost of the primary features in the host rocks and caused a complete recrystallisation and
\ncoarsening of the ore. The footwall to the deposit is a quartz-muscovite-sillimanite schist of
\nrhyolitic composition. The immediate hanging wall contains biotite-clinopyroxene-plagioclase
\nschist and amphibole-plagioclase schist of basaltic composition, which is overlain by a
\nsubstantial thickness of quartz-biotite-sillimanite schist of rhyodacite composition. The ore
\nposition is marked by metasediments including garnetifferous and graphitic metapelite. Analysis
\nof the carbon isotopes from the graphite suggests that the source of the carbon is biogenic,
\nwhich indicates a seafloor position.
\nUnlike many of the known and well studied VHMS deposits in the Snow Lake
\nAssemblage which have discordant pipe-like hydrothermal alteration with sericitized peripheries
\nand chloritized cores, the hydrothermal alteration in the Fenton Creek stratigraphy consists of
\nfault related K-feldspar-muscovite (formerly quartz-sericite alteration) that occurs in and around
\nthe fault zones and stratiform K-feldspar, muscovite, sillimanite, cordierite and cummingtonite
\n(formerly sericite +/- chlorite alteration) confined to the footwall. The footwall alteration is fairly
\nweak consistent with that found in a stratiform/blanket-like volcanic hosted massive sulphide
\nsystem. Mass balance calculations indicate that the footwall alteration reflects an overall loss in
\nSi, AI and Na with only minor gains in Ca and Mg.
\nThe ore lenses comprising the Fenton Creek zone contain three different types of
\nmineralisation that include disseminated, semi-massive and massive styles. The massive and
\nsemi-massive mineralisation consist of pyrrhotite +/- sphalerite-chalcopyrite while the
\ndisseminated mineralisation can be divided into three types of mineral associations (A) Pyrrhotite
\n+/- chalcopyrite-sphalerite, (8) Pyrrhotite +/- galena-chalcopyrite-tetrahedrite (C) Pyrrhotite +/graphite-
\nchalcopyrite-sphalerite. Spatially type 8 disseminated mineralized rock is observed
\nproximal to the semi-massive and massive mineralisation while type A and C were observed both
\nin and proximal to the semi-massive and massive styles of mineralisation. Metal zonation studies
\nof section 400N suggest that Zn and Cu dominate the upper lens whereas; the lower lens
\ncontains Pb, Ag, and Au. Plotting of the Zn ratio and the Cu ratio indicate the hottest portions of
\nthe ore lenses exist down plunge from the thickest portion of massive sulphide intersected.
\nGeologic features including the arc-rift related basaltic volcanic/volcaniclastic rocks in the
\nimmediate hanging wall, overlain by large thicknesses of rhyodacitic volcaniclastics and biogenic
\ncarbon in the graphite of the Fenton Creek zone suggest that it may have formed in rift
\nenvironment as a seafloor/sub-seafloor volcanic hosted massive sulphide deposit. This style of
\ndeposit may represent a new and previously unexplored mineralized stratigraphic position within
\nthe Snow Lake Assemblage.

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