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TitreMineralogy and styles of barite-rich Zn-Pb-Ba-Ag-Au mineralization in the Lemarchant volcanogenic massive sulfide (VMS) deposit
AuteurGill, S B; Piercey, S J; Devine, C A; Copeland, D A
SourceAssociation géologique du Canada-Association minéralogique du Canada, Réunion annuelle, Programme et résumés vol. 36, 2013 p. 103
LiensOnline - En ligne
Séries alt.Secteur des sciences de la Terre, Contribution externe 20140464
ÉditeurAssociation géologique du Canada
ÉditeurAssociation minéralogique du Canada
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
Lat/Long OENS -56.7500 -56.5833 48.6667 48.5000
Sujetsgîtes minéralogiques; gisements minéraux; gîtes volcanogènes; minéralisation; zinc; plomb; cuivre; argent; or; sulfures; gîtes sulfureux; barytine; sphalérite; pyrite; chalcopyrite; bornite; tétrahédrite; tennantite; stroméyérite; galène; faciès; altération; gisements stratiformes; Zone de Dunnage ; Ligne de Red Indian ; minéralogie; géologie économique; Paléozoïque; Cambrien
ProgrammeÉtude des gîtes de sulfures massifs volcaniques, Initiative géoscientifique ciblée (IGC-4)
Résumé(disponible en anglais seulement)
The Zn-Pb-Ba-Ag-Au Lemarchant volcanogenic massive sulfide (VMS) deposit is a recently discovered Kuroko-style VMS deposit located in the Central Mobile Belt, Newfoundland. The deposit has a geological resource (NI43-101 compliant) of 2.58 Mt at 0.49% Cu, 4.51% Zn, 1.01% Pb, 54.62g/t Ag, and 1.00 g/t Au. Characteristic of the deposit is an upper barite-rich zone that contains abundant sulfides, sulfosalts, and anomalous precious metals. Notably, while much of the barite is massive, bladed aggregates of barite are locally observed. The ore mineral assemblage in this zone consists of barite, abundant low-Fe (white-yellow) sphalerite, and Pb-Sb-Ag-As-bearing sulfosalts, including tennantite, tetrahedrite, friebergite, boulangerite, bournonite, and jamesonite, that are intergrown with bornite, galena, and chalcopyrite. Elevated Au values are associated with the barite-rich layer. Although minor visible free gold is present in the barite of some drill holes, Au is rarely observed and exists either sub-microscopically or as inclusions in other ore minerals such as pyrite and arsenopyrite. Silver occurs primarily in tetrahedrite, and as stromeryite associated with bornite and barite. Observed precious metal and mineral associations indicate that deposition within the barite-rich mineralization was likely from low temperature (<300°C) hydrothermal fluids. The barite layer may have influenced the anomalously high Au-Ag grade found at Lemarchant, acting as an insulator or chemical trap when the system was active to prevent dissipation of Au-Ag in hydrothermal fluid. The presence of large, tabular barite crystals associated with precious metals suggests fluid boiling at shallow water depths (<1500m). Further detailed mineralogical, mineral chemistry, sulfur isotope, and thermodynamic calculations are required to better understand the setting of mineralization at Lemarchant.