| Title | Expanding the size of multi-parameter metasomatic footprints in gold exploration: utilization of mafic dykes in the Canadian Malartic district, Quebec, Canada |
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| Author | Perrouty, S ;
Linnen, R L; Lesher, C M; Olivo, G R; Piercey, S J; Gaillard, N; Clark, J R; Enkin, R J |
| Source | Mineralium Deposita vol. 54, 5, 2019 p. 761-786, https://doi.org/10.1007/s00126-018-0829-x |
| Links | Erratum
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| Image |  |
| Year | 2019 |
| Alt Series | Natural Resources Canada, Contribution Series 20200256 |
| Publisher | Springer |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf |
| Province | Quebec |
| Lat/Long WENS | -79.5000 -77.0000 49.0000 48.0000 |
| Subjects | gold; deposition; cluster analyses; dykes, mafic; Abitibi Belt; Pontiac Subprovince; Malartic Volcanics |
| Illustrations | location maps; tables; photomicrographs; distribution diagrams; plots; ternary diagrams |
| Released | 2018 08 28 |
| Abstract | Ore-forming hydrothermal fluids react differently with different country rocks, but few studies have applied this knowledge with the specific goal of expanding the size of hydrothermal footprints in
mineral exploration. To develop this concept, 122 metamorphosed mafic dykes from the world-class Canadian Malartic gold district (18.6 Moz Au) were sampled and analyzed for mineralogy, physical properties, and lithogeochemistry (partial and total
digestion). The mafic dykes intrude mainly metasedimentary rocks, post-date D-1 deformation, and cross-cut early-D-2 quartz monzodiorite intrusions, but they were deformed and altered during D-2 deformation, mineralization, and metamorphism. They can
be subdivided into three groups: Group 1 dykes are least-altered, characterized by amphibole-rich regional metamorphic assemblages and distributed throughout the Pontiac Subprovince. Group 2 and 3 dykes underwent ore-related hydrothermal
biotite-calcite-pyrite alteration and are associated with density- and volume-adjusted concentration gains of over 100% in Au-W-Te-C-S-Ag-Cs-Mo-Cu-K-Rb-Se-U-Pb-Ba-F-Bi-Sn. They define a metasomatic footprint up to 6km away from the deposit toward the
SE and up to 2km away from the deposit toward the SW. Fifty-eight variables that define halos around the Canadian Malartic deposit have been identified and integrated using principal component analysis. PC1 explains 30% of the variance, separates
least-mobile elements from ore-related elements, and is interpreted to reflect the ore-forming alteration process. PC2 and PC3 represent igneous processes. PC4 highlights the calcite-pyrite and biotite alteration. Spatial variations of the modal
abundances of amphibole, biotite, calcite, and pyrite are the simplest expression of the metasomatic footprint, and they can easily be documented during exploration at the camp scale. |
| GEOSCAN ID | 326668 |
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