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TitreGeology of the banded iron formation-hosted Meadowbank gold deposit, Churchill Province, Nunavut
TéléchargerTéléchargement (publication entière)
AuteurJanvier, 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; par Dubé, B (éd.); Mercier-Langevin, P (éd.); Commission géologique du Canada, Dossier public 7852, 2015 p. 255-269,
ÉditeurRessources naturelles Canada
Documentdossier public
Mediaen ligne; numérique
Référence reliéeCette publication est contenue dans Dubé, B; Mercier-Langevin, P; (2015). Targeted Geoscience Initiative 4: Contributions to the understanding of Precambrian lode gold deposits and implications for exploration, Commission géologique du Canada, Dossier public 7852
SNRC66A/16; 66H/01
Lat/Long OENS -96.5000 -96.0000 65.2500 64.7500
Sujetsfer; formations ferrifères; Archéen; or; gisements minéraux; minéralisation; exploration; métallogénie; genèse des minerais; zones de failles; formation de fer d'Algoman; gîtes d'Algoman; analyses géochimiques; interprétations géochimiques; déformation; métamorphisme; volcanoclastique; géologie économique
Illustrationslocation maps; plots; photographs; cross-sections; ternary diagrams
Bibliothèque de Ressources naturelles Canada - Ottawa (Sciences de la Terre)
ProgrammeÉtude des gîtes d'or, Initiative géoscientifique ciblée (IGC-4)
Diffusé2015 06 11
Résumé(disponible en anglais seulement)
The 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.