GEOSCAN, résultats de la recherche


TitreThe Archean Westwood gold deposit, Abitibi: contrasting styles of auriferous mineralization and hydrothermal alteration
AuteurMercier-Langevin, P; Dubé, B; Yergeau, D; Galley, A; Wright-Holfeld, A; Hannington, M
SourceAssociation géologique du Canada-Association minéralogique du Canada, Réunion annuelle, Programme et résumés vol. 34, 2011 p. 140
LiensOnline - En ligne
Séries alt.Secteur des sciences de la Terre, Contribution externe 20130572
Réunion2011 GAC-MAC-SEG-SGA Joint Annual Meeting; Ottawa; CA; mai 25-27, 2011
Documentpublication en série
Lat/Long OENS-78.5000 -78.0000 48.2500 48.0000
Sujetsroches volcaniques; gisements minéraux; minéralisation; Archéen; gîtes volcanogènes; gîtes sulfureux; altération hydrothermale; gisements minéraux hydrothermaux; minéraux métalliques; Précambrien
ProgrammeÉtude des gîtes d'or, Initiative géoscientifique ciblée (IGC-4)
ProgrammeÉtude des gîtes d'or, Initiative géoscientifique ciblée (IGC-4)
Résumé(disponible en anglais seulement)
The Westwood gold deposit (reserves and resources of 9.35 Mt at 11.5 g/t Au, 3.4 Moz) is located in the ~26 Moz Au Doyon-Bousquet- LaRonde mining camp in the eastern part of the 2704-2695 Ma Blake River Group of the Abitibi belt. It is situated about 2 km east of the Doyon intrusion-associated Au±Cu quartz-pyrite vein deposit (5.4 Moz Au), 4 km west of the Bousquet 1 Au-rich sulphide stockwork-disseminated deposit (2.1 Moz Au), and approximately 8 km west of the Bousquet 2-Dumagami (3.9 Moz Au) and the LaRonde Penna Au-rich VMS deposits (9.2 Moz Au). The Westwood deposit is hosted in the highly strained, steeply dipping and south-facing volcanic rocks of the ca. 2700- 2696 Ma Bousquet Formation. The mineralization is located in three stacked corridors from north (base) to south (top): zone 2 extension, north and Westwood-Warrenmac. The partly transposed auriferous quartz-pyrite veins of the zone 2 extension are at a shallow angle with the stratigraphy and the east-trending foliation, in the lower part of the Bousquet Formation. These veins share strong analogies with the Doyon mine zones 1 and 2 vein systems. The north corridor mineralization is located in the central part of the Bousquet Formation and forms discontinuous auriferous sulphide- quartz veins and disseminations that show hybrid characteristics between “zone 2-type” veins lower in the stratigraphy and VMS-style mineralization higher in the stratigraphy. The ore zones of the Westwood-Warrenmac corridor, which are located in the same stratigraphic interval as the massive sulphide lenses at Bousquet 2-Dumagami and LaRonde Penna in the upper part of the Bousquet Formation, consist of stratiform auriferous semimassive to massive sulphide lenses containing significant amounts of Cu, Zn, and Ag. A genetic link between the intrusion-associated Au±Cu quartz-pyrite veins at Doyon and the Bousquet 2-Dumagami and LaRonde Penna Au-rich VMS deposits can be inferred at camp scale based on similar ages and overall geological settings. However a close examination of the relationships between the contrasting ore styles at Westwood is needed to confirm this hypothesis. Despite superimposed deformation and metamorphism that hinder recognition of primary relationships, preliminary results show that the different styles of mineralization are part of a pre-main stage deformation protracted volcano-plutonic hydrothermal system, with the large-scale VMS-associated alteration locally overprinted or telescoped by the Au±Cu vein-related alteration. This would perhaps suggest a setting similar to what is seen in younger belts where a genetic link between porphyry and epithermal Au-Cu systems has been demonstrated.