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TitleCharacterization of hydrothermal alterations at the Red Lake mine, northwestern Ontario
AuthorCadieux, A -M; Dubé, B; Williamson, K; Malo, M; Twomey, T
SourceGeological Survey of Canada, Current Research (Online) no. 2006-C2, 2006, 14 pages; 1 CD-ROM, (Open Access)
PublisherNatural Resources Canada
Mediaon-line; CD-ROM; digital
File formatpdf (Adobe Acrobat Reader)
AreaRed Lake
Lat/Long WENS-94.0000 -93.5000 51.2500 51.0000
Subjectsmineralogy; geochemistry; economic geology; hydrothermal alteration; alteration; biotitization; carbonatization; igneous rocks; volcanic rocks; basalts; breccias; mineralization; gold; geochemical analyses; Red Lake Gold District; aluminous alteration
Illustrationssketch maps; tables; photomicrographs; isocon diagrams; histograms; ternary diagrams
ProgramNSERC Natural Sciences and Engineering Research Council of Canada
Released2006 06 01
AbstractThe aim of this study is to characterize the hydrothermal alteration of the High Grade zone at the Red Lake mine, with a focus on the altered basalts as they constitute the main host to the ore. These basalts were affected by 1) bleaching (aluminous alteration), 2) garnet-magnetite alteration, 3) emplacement of carbonate-magnetite breccias, 4) biotite-carbonate alteration, and 5) arsenopyrite-rich replacement. The mineralogical assemblages described in the current study confirm that the sampled rocks are transitional between greenschist- and amphibolite-grade conditions. The majority of the minerals in these assemblages were formed during deformation. The biotite-carbonate alteration and the arsenopyrite-rich replacement zones are clearly associated with the gold mineralization, and the biotite they contain has the characteristic composition of magnesian biotite. All alteration types show a lower Na2O content than the least altered basalts. The biotite-carbonate alteration and the arsenopyrite-rich replacement zones, from which most of the mineralized samples were collected, show net mass gain due to a K2O, S, CO2 and SiO2 increase compared to the basalt protolith.