Geochemical and spectral footprint of metamorphosed and deformed VMS-style mineralization in the Quinns district, Yilgarn craton, Western Australia

Paul Duuring, L. Hassan, M. Zelic, Klaus Gessner

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    11 Citations (Scopus)

    Abstract

    © 2016 Society of Economic Geologists, Inc.
    Volcanic-hosted massive sulfide (VMS) occurrences in the Quinns district are hosted predominantly by ca. 2814-2800 Ma banded iron formation (BIF) within a sequence of rhyolite, basalt, and minor siltstone. The VMS occurrences and their surrounding rocks are folded, metamorphosed, and deeply weathered and variably covered by transported regolith. This study uses an integrated petrological and geochemical approach to map gradients in synvolcanic mineral and element abundances, with the aim of understanding the effects of postvolcanic processes on Archean VMS ore. Rhyolite-dominant footwall rocks and the BIF record kilometer-scale gradients in alteration mineral patterns and geochemistry. Rhyolite exposed throughout the district and intersected by drill holes records distal alteration assemblages of quartz-white mica ± chlorite. At the Austin deposit in the western part of the district, abundant talc and anthophyllite with minor cummingtonite and hornblende are associated with mineralization in the BIF, indicating intense magnesium metasomatism. Further away from mineralization, chlorite is the dominant alteration mineral. Adjacent rhyolite is altered to chlorite in proximal zones and white micas in more distal areas. Approaching known VMS prospects in the eastern half of the district, the rhyolite grades into a 2 × 1 km zone of schistose rhyolite with generally dispersed, but locally abundant, coarse-grained andalusite ± kyanite ± garnet rhyolitic schist. This broad Al-rich silicate alteration zone envelops two discrete 1 km × 500 m proximal alteration zones in rhyolite, defined by chlorite ± talc, with minor disseminated magnetite, pyrite, and chalcopyrite. The northernmost proximal alteration zone lies stratigraphically below the BIF-hosted Cu-Zn-rich gossan exposed near the Tasman prospect. The proximal zones are interpreted to be the result of the interaction between synvolcanic, Mg-rich fluids and rhyolite footwall at the time of VMS mineralization and BIF deposition.
    Original languageEnglish
    Pages (from-to)1411-1438
    JournalEconomic Geology
    Volume111
    Issue number6
    Early online date17 Jun 2016
    DOIs
    Publication statusPublished - Sep 2016

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  • Projects

    Multiscale Dynamics of Ore Body Formation

    McCuaig, C., Gessner, K., Hobbs, B., Ord, A., Gorczyk, W., Liu, J., APAI, N. N., APAI, U., Gerya, T., Lester, D. & Cawood, P.

    Australian Research Council

    1/01/104/09/15

    Project: Research

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