| Title | The Rainy River "atypical" Archean Au deposit, western Wabigoon Subprovince, Ontario |
| Download | Download (whole publication) |
| Author | Pelletier, M; Mercier-Langevin, P; Dubé, B; Crick, D; Tolman, J; McNicoll, V J; Jackson, S E; Beakhouse, G P |
| Source | Targeted 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. 193-207, https://doi.org/10.4095/296639 (Open Access) |
| Year | 2015 |
| Publisher | Natural Resources Canada |
| Document | open file |
| Lang. | English |
| Media | on-line; digital |
| Related | This 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 format | pdf |
| Province | Ontario |
| NTS | 52D/09; 52D/10; 52D/15; 52D/16; 52E/01; 52E/02 |
| Area | Rainy River |
| Lat/Long WENS | -95.0000 -94.0000 49.2500 48.5000 |
| Subjects | stratigraphy; structural geology; economic geology; geochronology; bedrock geology; structural features; Archean; mineralization; gold; mineral occurrences; igneous rocks; volcanic rocks; alteration;
deformation; uranium lead dates; Rainy River Gold deposit; Wabigoon Subprovince; Rainy River greenstone belt; Precambrian |
| Illustrations | location maps; photographs; plots; photomicrographs |
| Program | Gold Ore Systems, Targeted Geoscience Initiative (TGI-4) |
| Released | 2015 06 11 |
| Abstract | The Rainy River project, located in the western Wabigoon Subprovince in western Ontario, is an advanced Au exploration project with an estimated 6.2 Moz Au and 14.6 Moz Ag in reserves and resources (New
Gold Inc). The bulk of the Au and Ag mineralization occurs with pyrite, chalcopyrite, and sphalerite in disseminated } stockwork form, and part of the ore is within quartz-sulphide-tourmaline-carbonate veinlets that are subparallel to the main
east-trending, south-dipping penetrative foliation (S2). Folded and transposed veins of quartz, Fe-carbonate, and tourmaline contain higher Au values, with Au in its native form or as electrum. At deposit-scale, there is a relatively good correlation
between Au and Ag values, and between Au and Zn contents. Mineralization is concentrated in six zones that are elongated parallel to the main foliation. Higher grade zones are aligned within the main foliation plane along a stretching lineation (L2)
plunging to the southwest.
The deposit is hosted mainly within dacitic to rhyodacitic calc-alkaline volcanic domes, flows, and associated flow breccia. The rocks were regionally metamorphosed to greenschist facies. The proximal to immediate
alteration consists of a sericite }Fe-carbonate overprinted to various degrees by chlorite. Manganiferous garnet, chloritoid, and kyanite are present locally, in proximity to, or within, mineralized zones.
There is a strong correlation between the
spatial distribution of the mineralization and the sericite-dominated alteration. Moreover, there is a direct correlation of stronger alteration intensity, higher-grade and/or more extensive mineralization, and host rocks of higher initial porosity
(i.e. fragmental units), suggesting an early Au-Ag mineralization controlled by volcanism-related hydrothermal activity. Cross-cutting field relationships, preliminary laser-ablation inductively coupled plasma mass spectrometry analyses (LA-ICP-MS)
of pyrite grains, and U/Pb ID-TIMS zircon geochronology further support the hypothesis of a synvolcanic origin for at least part of the Au mineralization. Subsequent deformation and metamorphism are responsible for transposition of the mineralized
zones and metals within the main foliation plane and the associated stretching lineation, and for the modification of the primary alteration mineralogy to its greenschist-facies metamorphic equivalent. |
| GEOSCAN ID | 296639 |
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