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Musselwhite mine is located within the Weagamow – North Caribou Greenstone Belt of the Sachigo Subprovince, part of the Archean Superior Province. The stratigraphy in the immediate mine vicinity is dominated by mafic volcanics, chemical sediments and felsic volcanics. External to the supracrustal sequences are a series of undifferentiated gneisses and granitoids. All lithologies within the immediate mine area have been metamorphosed at mid to upper amphibolite facies. Although the mine scale deformation is considered to form part of a progressive deformation event, it is possible to differentiate four local deformation events. The D2 deformation event is the dominant and most easily recognized and is responsible for the large scale folding of all lithologies and the development of very strong local axial planar, penetrative fabrics. The D3 event is considered to be syn D2 to late D2 and is dominated by the development of ductile shear zones and areas of intense cleavage development. Gold mineralization is associated with the D2/D3 event.
Mineralization is predominantly hosted within meta-chemical sediments (banded iron formations) and in particular within garnet-magnetite-grunerite facies meta-banded iron formations (locally termed the Northern Iron Formation). The location of mineralization is controlled by the intersection of D3 shears zones and D2 folded meta-banded iron formations. These geological controls result in mineralized shoots, which plunge at approximately 15 degrees to grid north, have a down dip extent of up to 150 m, down plunge continuation in excess of 1.5 kilometres, and across-lithology width of up to 10 m. Mineralized zones are characterized by abundant pyrrhotite, quartz flooding and, rarely, visible gold.
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