GEOSCAN Search Results: Fastlink


TitleVolcaniclastic rocks of the Bousquet scoriaceous tuff units north of the LaRonde Penna mine, Doyon-Bousquet-LaRonde mining camp, Abitibi Greenstone Belt, Quebec
AuthorMercier-Langevin, P; Ross, P -S; Lafrance, B; Dubé, B
SourceGeological Survey of Canada, Current Research (Online) no. 2008-11, 2008, 19 pages, (Open Access)
PublisherNatural Resources Canada
Mediaon-line; digital
File formatpdf (Adobe Acrobat Reader)
NTS32D/01NW; 32D/02NE; 32D/07SE; 32D/08SW
AreaBousquet; LaRonde; Doyon; Abitibi
Lat/Long WENS-78.7500 -78.2500 48.3333 48.1667
Subjectseconomic geology; stratigraphy; geochronology; mineral occurrences; mineral deposits; gold; mineralization; volcanogenic deposits; sulphides; sulphide deposits; igneous rocks; volcanic rocks; volcaniclastics; tuffs; breccia deposits; breccias; breccias, volcanic; Archean; rhyolites; dykes; diabase dykes; uranium lead dates; Doyon-Bousquet-LaRonde Mining Camp; LaRonde Penna Deposit; Abitibi Greenstone Belt; Hébécourt Formation; Bousquet Formation; Blake River Group; Precambrian
Illustrationslocation maps; tables; stratigraphic columns; stratigraphic sections; photographs; plots
ProgramTargeted Geoscience Initiative (TGI-3), 2005-2010
Released2008 06 01; 2008 06 02
AbstractThe Doyon-Bousquet-LaRonde mining camp, located in the Abitibi subprovince, hosts several gold-rich volcanogenic massive sulphide deposits and comprises two formations: Hébécourt and Bousquet. The younger Bousquet Formation is subdivided into two members. Its 200-600 m thick lower member includes, at its base, the 80-300 m thick Bousquet scoriaceous tuff units.

Detailed (1:50) mapping through the Bousquet scoriaceous tuff units northeast of the LaRonde Penna mine reveals complexities in an approximately 26 m thick section that consists of intermediate, massive to normally graded, polymict, poorly sorted lapilli tuff or tuff breccia that are interbedded with two decimetre- to metre-thick rhyolitic tuff units and overlain by metre-thick beds of nearly monomict, poorly sorted, nongraded, mafic tuff breccia. The lowermost intermediate lapilli tuff and tuff breccia of the section are invaded by coherent, feldspar-phyric felsic sills or lobes. These compositionally varying volcaniclastic deposits are interpreted to have been emplaced as high-concentration submarine density currents, possibly of the eruption-fed type.

There are no direct links between the Bousquet scoriaceous tuff units and the ore bodies of the Bousquet Formation located higher in the stratigraphy; however, the absence of voluminous, explosively generated rocks in the footwall sequence of the deposits supposes that no dramatic magmatic degassing events happened prior to sulphide deposition. This may also suggests a low magmatic volatile content in the source chamber and/or a confi ning pressure high enough to suppress explosive activity. It also raises the possibility that large amounts of volatiles were made available to contribute to the volcanogenic massive sulphide-forming hydrothermal cell later in the evolution of the Bousquet Formation.