GEOSCAN, résultats de la recherche


TitreUsing physical volcanology, chemical stratigraphy, and pyrite geochemistry for volcanogenic massive sulfide exploration: an example from the Blake River Group, Abitibi greenstone belt
AuteurRogers, R; Ross, P S; Goutier, J; Mercier-Langevin, P
SourceEconomic geology and the bulletin of the Society of Economic Geologists vol. 109, no. 1, 2014 p. 61-88,
Séries alt.Secteur des sciences de la Terre, Contribution externe 20110204
Documentpublication en série
Mediapapier; en ligne; numérique
SNRC32D/05; 32D/11
Lat/Long OENS-79.5100 -79.3767 48.5278 48.4717
Sujetsvulcanologie; analyses stratigraphiques; pyrite; gîtes volcanogènes; gîtes sulfureux; méthodes d'exploration; lithologie; rhyolites; minéralisation; gisements minéraux hydrothermaux; roches volcaniques; tholéiites; andésites; analyses géochimiques; corrélations stratigraphiques; altération; altération hydrothermale; Archéen; Groupe de Blake River ; Ceinture d'Abitibi Greenstone ; Formation d'Hebecourt ; géochimie; minéraux métalliques; stratigraphie; Précambrien
Illustrationsgeological sketch maps; photographs; analyses
ProgrammeAbitibi IGC-3, Initiative géoscientifique ciblée (IGC-3), 2005-2010
ProgrammeÉtude des gîtes de sulfures massifs volcaniques, Initiative géoscientifique ciblée (IGC-4)
ProgrammeÉtude des gîtes d'or, Initiative géoscientifique ciblée (IGC-4)
Résumé(disponible en anglais seulement)
An innovative approach to enhance volcanogenic massive sulfide (VMS) exploration in regions outside of mining camps is to first use physical volcanology with litho- and chemostratigraphy to establish the location of effusive centers in the volcanic units and use pyrite geochemistry in sulfide-bearing stratified intervals with whole-rock geochemistry in the underlying volcanic units to identify hydrothermal upflow zones.
This methodology is illustrated by this study in the Archean Blake River Group within the Abitibi greenstone belt of Quebec and Ontario. The Blake River Group contains numerous VMS deposits, yet large segments remain underexplored, including the Hébécourt Formation which contains four tholeiitic units that range from basalt to rhyolite in composition. Effusive centers are located for three felsic units and subunits: (1) low Ti (porphyritic) subunit of the main rhyolite, (2) high Ti (aphyric) subunit of the main rhyolite, and (3) the upper rhyolite, and for a basaltic andesite unit. Stringer and disseminated Zn-Cu mineralization occurs within the flank breccia of the low Ti rhyolite dome. An inferred vent area for an overlying basaltic andesitic unit has also been identified in this area, illustrating the coincidence of hydrothermal upflow zones with volcanic vents.
LA-ICP-MS analysis of pyrite grains from several sulfide-bearing stratified intervals indicates two broad areas of higher Cu, Zn, Au, and Ag contents. The eastern region corresponds to known volcanic vents and mineralization. The western region also indicates upflow of Cu-bearing hydrothermal fluids and corresponds to a possible effusive center for the high Ti subunit. The western region does not contain known mineralization at lower stratigraphic positions, but it has not been thoroughly explored.