GEOSCAN Search Results: Fastlink


TitleVolcanology and geochemistry of the Monsabrais area, Blake River Group, Abitibi Greenstone Belt, Quebec: implications for volcanogenic massive sulphide exploration
AuthorRoss, P -S; Goutier, J; McNicoll, V J; Dubé, B
SourceGeological Survey of Canada, Current Research (Online) no. 2008-1, 2008, 18 pages, (Open Access)
PublisherNatural Resources Canada
Mediaon-line; digital
File formatpdf (Adobe Acrobat Reader)
NTS32D/03NW; 32D/06SW
AreaMonsabrais; Lake Monsabrais; Lake Duparquet; 13
Lat/Long WENS-79.5000 -79.2500 48.4167 48.2000
Subjects23; economic geology; geochemistry; mineral deposits; mineral occurrences; mineral exploration; mineralization; volcanogenic deposits; sulphides; sulphide deposits; base metals; base metal deposits; igneous rocks; plutonic rocks; volcanic rocks; volcaniclastics; andesites; tuffs; lithofacies; Archean; Blake River Group; Abitibi Greenstone Belt; Monsabrais Pluton; Precambrian
Illustrationssketch maps; plots; graphs; photographs; photomicrographs
ProgramTargeted Geoscience Initiative (TGI-3), 2005-2010
ProgramNSERC Natural Sciences and Engineering Research Council of Canada
Released2008 03 01
AbstractThe ca. 2.70 Ga Blake River Group in the southern Abitibi Greenstone Belt (Quebec and Ontario) hosts numerous volcanogenic massive sulphide deposits. The peripheral areas of this group contain a greater proportion of volcaniclastic rocks than the traditional 'central camp', and also host some of the largest volcanogenic massive sulphide mines, including LaRonde-Penna and Bouchard-Hébert.
These represent deposits formed in part by subseafl oor replacement in permeable fragmental rocks. Many peripheral sectors of the Blake River Group have been less intensely explored, yet hold potential for volcanogenic massive sulphide mineralization, especially if volcanic centres can be identifi ed. Two basemetal deposits, Magusi River and Fabie Bay, are found just south of the Monsabrais area. Both are partly hosted by andesitic fragmental rocks. In this report, the authors examine the lithofacies and geochemistry of the Monsabrais area, interpreted as a distinct volcanic centre. It includes a synvolcanic intrusion, the Monsabrais Pluton, newly dated at 2696.2 ± 0.9 Ma. The Monsabrais volcaniclastic rocks - many of which lack bedding or grading and are intimately intermixed with coherent subaqueous lava fl ows - are dominantly interpreted as hyaloclastite. Observations supporting this interpretation also include the monomictic character of many facies, jigsaw-fi t textures, curviplanar clast outlines, and gradations into massive lava. Pyroclastic fl ow deposits do not represent a signifi cant volume in the Monsabrais area. This has implications for the recently proposed Blake River Group megacaldera model, which relies in part on a semicontinuous belt of 'ignimbrites' (pyroclastic fl ow deposits) to trace the caldera margin.