GEOSCAN, résultats de la recherche


TitreAn overview of selected research on the genesis of, and exploration methodologies for volcanogenic massive sulfide deposits under the Targeted Geoscience Initiative 4 (TGI-4) Program
AuteurPeter, J M; Mercier-Langevin, P; Laakso, K; Tivard, B; Taylor, B; McClenaghan, M B; Caté, A; Duff, S; Pilote, J -L; Gill, S; Piercey, S J; Bouerice, A; Ross, P -S; Hannington, M D
SourceL'Association géologique du Canada-L'Association minéralogique du Canada, Réunion annuelle conjointe, Recueil des résumés vol. 37, 2014 p. 220-221
LiensOnline - En ligne
Séries alt.Secteur des sciences de la Terre, Contribution externe 20130550
RéunionGAC-MAC 2014; Joint annual meeting of Geological Association of Canada and Mineralogical Association of Canada; Fredericton; CA; mai 21-23, 2014
Documentpublication en série
SujetsArchéen; gîtes volcanogènes; gîtes sulfureux; altération; métamorphisme; assemblages de minéraux; minéralisation; directives d'exploration; roches volcaniques; gisements minéraux; or; géologie économique; Précambrien
ProgrammeÉtude des gîtes de sulfures massifs volcaniques, Initiative géoscientifique ciblée (IGC-4)
Résumé(disponible en anglais seulement)
TGI-4 is a federal program focused on providing new innovative geoscience knowledge and techniques for more effective targeting of deeply buried mineral deposits. Volcanogenic massive sulphides (VMS) are 1 of the 7 ore systems being studied, with research activities focused on 2 main themes: 1) Innovative, new and unconventional detection and vectoring methodologies for VMS exploration (activities: spectral geology/geochemistry and oxygen isotope mapping/vectoring, portable x-ray fluorescence (PXRF) spectrometry for till surveying, integration of rock properties with geophysics, volatile element vectoring); 2) Controls on precious metal endowment and enrichment in VMS deposits (activities: geological, geochemical, and mineralogical characterization of several Au-bearing deposits). The Izok Lake area, NU was used to test the efficacy of airborne and ground spectrometry, together with oxygen isotope mapping to delineate hydrothermally altered felsic volcanic rocks associated with mineralization. Within both the airborne dataset and the ground outcrop and drillcore data, there are systematic shifts in the wavelength of the 2200nm absorption feature of white mica and the 2250nm absorption feature of chlorite that, together with variations in the bulk oxygen isotope composition reflect paleohydrothermal fluid pathways that may serve as exploration vectors. In the Halfmile Lake deposit area (Bathurst camp, NB), a comparison of standard laboratory till geochemical analyses with PXRF data for processed samples show comparable results. PXRF data for unprocessed tills give slightly lower abundances of some elements due to the matrix effects of moisture. Thus, PXRF can be used to guide and optimize a till sampling program using conventional methods. Although the VMS model is well established, precious metal enrichment processes are less well understood. Several deposits were studied (Lalor-Snow Lake camp, MB; Ming- Rambler camp, NL; Lemarchant-Tally Pond belt, NL; Lemoine-Abitibi belt, QC). At Lalor, Au is associated with several ore mineral assemblages, each with distinct metamorphosed alteration assemblages. The Au-bearing zones are all within footwall hydrothermally altered rocks, indicated that Au introduction is primary. At Lemoine and Ming Au is also thought to be syngenetic. Introduction of Au at Lemoine was multiphase and is associated with Bi in sulfosalts; at Ming, Au is overgrown by Cu-rich mineralization. At Lemarchant, Au and Ag are enriched with a high-sulfidation epithermal suite in mineralization comprised in part of sulfosalts and low-Fe sphalerite. Mineralization formed in the subsurface via replacement in relatively shallow water. Characteristic trace element enrichments (Sn, In, Sb, Au) and light sulfur isotopic value suggest a contribution from magmatic fluid.