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TitleGeology, mineralization and alteration of the turbidite-hosted Mustang Au showing, Lower Eastmain greenstone belt, Superior Province, Quebec
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AuthorBeauchamp, A -M; Dubé, B; Malo, M; McNicoll, V J; Brisson, T; Archer, P; Lavoie, J; Chartrand, F
SourceTargeted Geoscience Initiative 4: Contributions to the understanding of Precambrian lode gold deposits and implications for exploration; by Dubé, B (ed.); Mercier-Langevin, P (ed.); Geological Survey of Canada, Open File 7852, 2015 p. 227-243, (Open Access)
PublisherNatural Resources Canada
Documentopen file
Mediaon-line; digital
RelatedThis publication is contained in Dubé, B; Mercier-Langevin, P; (2015). Targeted Geoscience Initiative 4: Contributions to the understanding of Precambrian lode gold deposits and implications for exploration, Geological Survey of Canada, Open File 7852
File formatpdf
NTS33C/01; 33C/02; 33C/07; 33C/08
AreaJames Bay
Lat/Long WENS -76.5833 -76.4167 52.3333 52.0000
Subjectseconomic geology; structural geology; geochronology; Archean; mineral occurrences; mineral deposits; mineralization; gold; copper; base metals; base metal deposits; deformation; alteration; hydrothermal alteration; igneous rocks; metamorphism; tectonic interpretations; tectonic setting; turbidites; structural features; uranium lead dates; Mustang Gold showing; Eastmain greenstone belt; Precambrian
Illustrationslocation maps; photographs; stereonets; histograms; photomicrographs; plots
ProgramTargeted Geoscience Initiative (TGI-4), Gold Ore Systems
Released2015 06 11
AbstractThe Mustang gold showing is located on the Wabamisk property owned by Exploration Osisko - Baie James. The Mustang Vein (N240/80°) is located near the contact between the La Grande and Opinaca subprovinces in the Superior Province, 65 km southwest of the Éléonore gold mine. The gold zone is exposed on surface and can be traced through drillholes over a strike length of 570 m and to a depth of 225 m. The vein and its mineralized envelope range from a few centimetres to six metres in width. Gold values obtained for the vein reach 111.17 g Au/t over 2.6 m in channel sample and 22.65 g Au/t over 2.25 m in drillhole. More than 75 gold showings (Au >500 ppb) were discovered over a 10 by 10 km area around the Mustang Vein. The Mustang Vein is a quartz (±carbonate) laminated vein hosted in turbiditic metasedimentary rocks (greenschist facies) located near the top of an Archaean stratigraphic sequence of the Eastmain Belt. The preliminary results of U-Pb dating on detrital zircons of the metasedimentary rocks hosting the Mustang Vein indicate a maximum deposition age of 2709 ±4 Ma. The sedimentary sequence has undergone at least three deformation phases, including an initial phase of north-northwest-oriented folding with F1 folds refolded by east-northeast-oriented F2 folds. The S2 foliation is oriented east-northeast with a steep dip and an axial plane with P2 folds. The D3 deformation phase is characterized by a moderate-dip, southwest-oriented crenulation cleavage. The Mustang Vein is subparallel to the bedding and folded into S shapes by the F2 folds. It is interpreted as syn-D2 regional deformation, along a F2 fold limb. The vein and the altered walls (potassic alteration and carbonatization) contain 1-10% arsenopyrite, 5-10% pyrrhotite, with traces of pyrite, chalcopyrite, galena, and sphalerite. Locally, gold grains in the veins and altered host rock are disseminated and aligned on the main S2 foliation planes.
The geological context and mineralization, alteration, and deformation styles at the Mustang showing are analogous to syn-deformation deposits hosted in turbidite sequences (e.g. Meguma in Nova Scotia and Central Victoria in Australia). Like the Roberto Gold Deposit (Éléonore Mine), the Mustang gold showing illustrates the potential for folded Archaean metasedimentary assemblages of the La Grande Subprovince proximal to the tectono-metamorphic boundary of the Opinaca Subprovince to host major gold deposits in the James Bay Region.