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TitleGold-rich volcanogenic massive sulphide deposits
AuthorDubé, B; Gosselin, P; Mercier-Langevin, P; Hannington, M; Galley, A
SourceMineral deposits of Canada: a synthesis of major deposit-types, district metallogeny, the evolution of geological provinces, and exploration methods; by Goodfellow, W D (ed.); Geological Association of Canada, Mineral Deposits Division, Special Publication no. 5, 2007 p. 75-94
Alt SeriesEarth Sciences Sector, Contribution Series 20070190
PublisherGeological Association of Canada, Mineral Deposits Division (St. John's, NL, Canada)
Mediapaper; DVD
RelatedThis publication is contained in Goodfellow, W D; (2007). Mineral deposits of Canada: a synthesis of major deposit-types, district metallogeny, the evolution of geological provinces, and exploration methods, Geological Association of Canada, Mineral Deposits Division, Special Publication no. 5
File formatpdf
ProvinceBritish Columbia; Alberta; Saskatchewan; Manitoba; Ontario; Quebec; New Brunswick; Nova Scotia; Prince Edward Island; Newfoundland and Labrador; Northwest Territories; Yukon; Nunavut
NTS1; 2; 3; 10; 11; 12; 13; 14; 15; 16; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30; 31; 32; 33; 34; 35; 36; 37; 38; 39; 40; 41; 42; 43; 44; 45; 46; 47; 48; 49; 52; 53; 54; 55; 56; 57; 58; 59; 62; 63; 64; 65; 66; 67; 68; 69; 72; 73; 74; 75; 76; 77; 78; 79; 82; 83; 84; 85; 86; 87; 88; 89; 92; 93; 94; 95; 96; 97; 98; 99; 102; 103; 104; 105; 106; 107; 114O; 114P; 115; 116; 117; 120; 340; 560
AreaDoyon; LaRonde; Bousquet
Lat/Long WENS-141.0000 -50.0000 90.0000 41.7500
Subjectseconomic geology; metallic minerals; mineralogy; mineral occurrences; mineral deposits; gold; copper; lead; zinc; mineralization; volcanogenic deposits; sulphide deposits; sulphides; igneous rocks; volcanic rocks; intrusive rocks; metamorphism; deformation; alteration; hydrothermal alteration
Illustrationssketch maps; photographs; tables; cross-sections
ProgramConsolidating Canada's Geoscience Knowledge
ProgramTargeted Geoscience Initiative (TGI-3), 2005-2010
AbstractGold-rich volcanogenic massive sulphide deposits (Au-rich VMS) form a subtype of both volcanogenic massive sulphide and lode-gold deposits. Their diagnostic features are stratabound to discordant, volcanic-hosted massive sulphide lenses with associated discordant stockwork feeder zones in which average Au grades (in g/t) exceed associated combined Cu, Pb, and Zn grades (in weight percent); Au is thus the main commodity. The Au-VMS deposits are present in both recent seafloor and deformed and metamorphosed submarine volcanic settings. They occur in a variety of volcanic terranes from mafic bimodal through felsic bimodal to bimodal siliciclastic in greenstone belts of all ages, typically metamorphosed to greenschist and lower amphibolite facies, and intruded by subvolcanic intrusions and dykesill complexes. The deposits are commonly located in proximity of intermediate to felsic volcanic centres, at or close to the interface between intermediate to felsic volcanic domes and basalt-andesite or clastic sediments. Several of the largest Au-VMS deposits are located in Canada: Horne, Bousquet 2-Dumagami, LaRonde Penna, and Eskay Creek. The first three deposits are hosted within the Archean Blake River Group, which is therefore an important geological assemblage for this style of Au deposit.

In metamorphosed greenstone terranes, the gangue minerals may include quartz, sericite, aluminous silicates, such as andalusite, kyanite, pyrophyllite, and Zn-rich staurolite, and Mn-rich garnet. Sulphide minerals are mainly pyrite and base-metal sulphides with a complex assemblage of minor phases including bornite, tennantite, sulphosalts, arsenopyrite, mawsonite, and tellurides. The Au has most commonly an uneven distribution within the deposit due to both primary depositional controls and subsequent tectonic remobilization. The chemical signature of the ore is diverse, and dominated by Au, Ag, and Cu or Zn with locally high concentrations of As, Sb, Bi, Pb, Se, Te, and Hg. The Eskay Creek deposit is a low-temperature Au-rich VMS deposit characterized by a mineralogical assemblage of stibnite, realgar, cinnabar, and arsenopyrite with various proportions of barite. It is clearly distinct from other Au-rich VMS deposits.

Potassic alteration characterized by K-feldspar, typical of deposits with an Au-Zn-Pb-Ag association, occurs at Eskay Creek, especially in the footwall alteration zone. The advanced argillic alteration found at LaRonde Penna and Bousquet 2-Dumagami is thought to be typical of deposits from the Au-Cu association. Where present, the metamorphosed advanced argillic and more discrete massive silicic alteration assemblages indicate high-sulphidation conditions similar to those encountered in some epithermal environments.
There are two genetic models for Au-rich VMS: 1) conventional syngenetic volcanic-hosted Au-poor VMS mineralization overprinted during regional deformation by Au mineralization; and 2) syngenetic VMS deposits characterized by an anomalous fluid chemistry (with magmatic input) and/or deposition within a shallow-water to subaerial volcanic setting equivalent to epithermal conditions, in which boiling may have had a major impact on the fluid chemistry. The deformation and metamorphism that commonly overprint the mineralization in ancient terranes have obscured the original relationships and led to considerable debate about the syntectonic versus synvolcanic origin of Au-rich VMS.