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TitleCanadian shield / Bouclier canadien
LicencePlease note the adoption of the Open Government Licence - Canada supersedes any previous licences.
AuthorGeological Survey of Canada
SourceGeological Survey of Canada, Current Research no. 1997-C, 1997, 254 pages, Open Access logo Open Access
PublisherNatural Resources Canada
Lang.English; French
Mediapaper; on-line; digital
RelatedThis publication contains the following publications
File formatpdf
Subjectseconomic geology; geochemistry; geochronology; metallic minerals; stratigraphy; geophysics; igneous and metamorphic petrology; surficial geology/geomorphology; structural geology; lithology; mineral deposits; metamorphism; metamorphic rocks; plutonic rocks; volcanic rocks; igneous rocks; sedimentary rocks; geophysical surveys; structural features; mineralization; stratigraphic analyses; metallogeny; radiometric dates; glacial deposits; geochemical surveys; Canadian Shield; Precambrian
Released1997 02 01; 2013 04 30
AbstractTwo magnetite-rich deposits at Tommie Lake are hosted by an east-trending, steeply dipping assemblage of rhyolite ignimbrite, tuff, and porphyritic dacite that underlies this region in the north-central part of the continental, ca. 1860 Ma old Great Bear magmatic zone. One of the deposits is stratiform in a tuffaceous horizon, and contains disseminated pyrite and chalcopyrite in magnetite layers. The other, located 1 km to the south, is vein type. The veins contain variable amounts of quartz, magnetite, pyrite, and chalcopyrite, and locally calcite and fluorite. Notable amounts of gold and tungsten occur in chalcopyi-iterich veins.
The deposits attest to an initial synvolcanic stratiform concentration of the metals, and later hydrothermal activity related to granitic plutonism that remobilized and/or added various elements. The hydrothermal mineralization is akin to polymetallic magnetite-rich mineralization elsewhere in the magmatic zone regarded as Kiruna/Olympic Dam type.

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