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TitleGeology of the banded iron formation-hosted Meadowbank gold deposit, Churchill Province, Nunavut
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AuthorJanvier, V; Castonguay, S; Mercier-Langevin, P; Dubé, B; Malo, M; McNicoll, V J; Creaser, R A; de Chavigny, B; Pehrsson, S J
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. 255-269, https://doi.org/10.4095/296646 (Open Access)
Year2015
PublisherNatural Resources Canada
Documentopen file
Lang.English
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
ProvinceNunavut
NTS66A/16; 66H/01
Lat/Long WENS -96.5000 -96.0000 65.2500 64.7500
Subjectseconomic geology; iron; iron formations; Archean; gold; mineral deposits; mineralization; exploration; metallogeny; ore mineral genesis; fault zones; Algoma type iron formations; Algoma type deposits; geochemical analyses; geochemical interpretations; deformation; metamorphism; volcaniclastics; Meadowbank deposit; banded iron formations
Illustrationslocation maps; plots; photographs; cross-sections; ternary diagrams
ProgramGold Ore Systems, Targeted Geoscience Initiative (TGI-4)
Released2015 06 11
AbstractThe Meadowbank gold deposit is hosted in ca. 2711 Ma banded iron formation (BIF) successions within the polydeformed and metamorphosed Woodburn Lake Group. This volcano-sedimentary sequence comprises several similar BIF successions of which only one contains economical gold mineralization. Deposit host rocks consist of greenschist- to amphibolite-facies, intermediate to felsic volcaniclastic rocks, mafic and ultramafic rocks, quartzite and BIF. Notwithstanding cryptic and strongly overprinted Archean tectonism, four phases of Proterozoic Trans-Hudsonian deformation have been regionally documented. In the Meadowbank deposit area, several generations of structures are recognized: 1) isoclinal F1 folds and D1 faults strongly overprinted by 2) south-trending isoclinal F2a folds and associated D2 fault zones that cut mineralized zones. Late D2 deformation consists of north-trending gentle F2b folds, 3) open to closed southwest- plunging megascopic F3 folds, and 4) south-verging shallowly to moderately inclined, open to tight, chevron-style F4 folds.
The bulk of the gold is hosted in BIF and is associated with pyrrhotite +-pyrite and traces of chalcopyrite and arsenopyrite. Gold-rich quartz-pyrrhotite +-pyrite veins cut intercalated intermediate to felsic volcaniclastic rocks. The ore-associated mineral assemblage includes grunerite and chlorite within BIF, whereas muscovite, chlorite, and pyrite represent the dominant mineral assemblage of altered volcaniclastic rocks. Biotite, Fe-Mg amphibole, and garnet occur in variable modal abundance in the southern part of the deposit, where metamorphic grade is higher.
Crosscutting relationships suggest that most of the gold was preferentially introduced along D1 faults and was likely remobilized during D2 deformation, especially along sheared contacts and F2a fold limbs. Deposit- and regional-scale lithogeochemistry coupled with new U-Pb zircon ages indicate that the Meadowbank deposit is located at or near the boundary between two distinct lithological assemblages (2711 Ma and 2717 Ma), which are separated by long-lived fault zones that potentially controlled the occurrence and geometry of the Meadowbank deposit.
GEOSCAN ID296646