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TitreGeodynamic influences on the genesis of Archean world-class gold-rich VMS deposits: examples from the Blake River Group, Abitibi greenstone belt, Canada
AuteurMercier-Langevin, P; Hannington, P; Dubé, B; McNicoll, V; Goutier, J; Monecke, T
SourceAssociation géologique du Canada-Association minéralogique du Canada, Réunion annuelle, Programme et résumés vol. 36, 2013 p. 144-145
Séries alt.Secteur des sciences de la Terre, Contribution externe 20130545
ÉditeurGAC MAC
RéunionGAC-MAC 2013; Joint annual meeting of Geological Association of Canada and Mineralogical Association of Canada; Winnipeg; CA; mai 22-24, 2013
Documentpublication en série
Mediaen ligne; numérique
SNRC32D/03NE; 32D/06; 32D/07
Lat/Long OENS -79.5000 -78.5000 48.5000 48.1667
Sujetsgîtes minéralogiques; gisements minéraux; potentiel minier; minéralisation; or; gîtes volcanogènes; sulfures; gîtes sulfureux; lithogéochimie; ceintures de roche verte; roches vertes; roches ignées; roches volcaniques; tholéiites; basaltes; andésites; lithostratigraphie; Archéen; Ceinture d'Abitibi Greenstone ; Dépôt de Laronde Penna ; Groupe de Blake River ; Dépôt de Bousquet ; Dépôt de Doyon ; géologie économique; pétrologie ignée et métamorphique; Précambrien; Protérozoïque
ProgrammeÉtude des gîtes de sulfures massifs volcaniques, Initiative géoscientifique ciblée (IGC-4)
LiensOnline - En ligne
Résumé(disponible en anglais seulement)
Six of the world's richest and largest gold-rich volcanogenic massive sulphide (VMS) deposits are located in the 2704-2695 Ma Blake River Group (BRG) of the Abitibi greenstone belt, including the two largest ever found (Horne: 54 Mt, 328 t Au, and LaRonde Penna: 80 Mt, 290 t Au), suggesting district and deposit-scale primary geological control(s) on the gold enrichment in VMS deposits. The gold-rich VMS deposits of the BRG are found in distinctly different volcanic and structural settings from other “conventional” VMS deposits in the district. The ~2701 Ma Horne gold-rich deposit is separated in time and space from the ~2698 Ma Noranda Mine Sequence Cu-Zn VMS; it is located in the southern part of the Noranda camp in fault-bounded structural blocks separated from the slightly younger Cu-Zn deposits. The Bousquet Formation, which hosts the ~2698 Ma LaRonde Penna deposit, was coeval with the volcanic rocks that host the Cu-Zn VMS of the Noranda Mine Sequence but is distinguished by its transitional to calc-alkaline affinity and dominantly felsic composition. The Bousquet Formation is thought to have been formed in a volcanic complex at the periphery of the central part of the BRG, possibly in an area characterized by a thicker crust undergoing early extension and closer to an inferred arc (immature or early arc-rift stage). Recent dating in the BRG indicates that Horne also formed during an episode of early extension-subsidence and transitional felsic volcanism at Noranda (2702-2701 Ma). Extension, VMS-related hydrothermal activity and transitional to calc-alkaline volcanism moved away from the central part of the BRG, and by 2698-2697 Ma, at which time Horne had already formed, the Cu-Zn deposits of the Noranda Mine Sequence were being deposited in the more mature, tholeiitic to transitional, mafic-dominated extensional setting. Despite obvious limitations of reconstructions of Archean volcanic complexes, analogies can be made with the architecture and evolution of modern volcanic arcs such as those formed along the western Pacific. The BRG gold-rich VMS deposits were formed during incipient extension episodes at different times and places in a setting that is thought to have been transitional between arc and back-arc regions. Specific time-stratigraphic intervals related to arc extension are viewed as an important guide to exploration for gold-rich VMS in ancient volcanic belts. The concentration of gold-rich VMS deposits in the eastern BRG highlights a region with favourable gold “heritage”, where gold deposits of multiple ages and styles are formed throughout the evolution of the belt.