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TitleHeavy mineral signature of the NICO Co-Au-Bi deposit, Great Bear magmatic zone, Northwest Territories, Canada
AuthorMcMartin, I; Corriveau, L; Beaudoin, G; Averill, S; Kjarsgaard, I
SourceIndicator mineral methods in mineral exploration, workshop B, 24th international applied geochemistry symposium; 2009 p. 71-81
LinksCanadian Database of Geochemical Surveys, downloadable files
LinksBanque de données de levés géochimiques du Canada, fichiers téléchargeables
Alt SeriesEarth Sciences Sector, Contribution Series 20080750
Meeting24th International Applied Geochemistry Symposium (IAGS 2009); Fredericton (New Brunswick; CA; June 1 - 4, 2009
ProvinceNorthwest Territories
NTS85N; 86C; 86D; 86E; 86F; 86K; 86L
AreaGreat Bear Lake; Lac la Martre; Hottah Lake
Lat/Long WENS-119.0000 -116.0000 67.0000 63.0000
Subjectsgeochemistry; economic geology; mineral occurrences; cobalt; gold; bismuth; copper; heavy minerals; heavy mineral analyses; heavy minerals geochemistry; magnetite; Great Bear magmatic zone; NICO deposit; Sue-Dianne deposit
Illustrationslocation maps; tables; photomicrographs; plots
ProgramGEM: Geo-mapping for Energy and Minerals
As part of a joint government-industry-academia research project in the Great Bear magmatic zone (central NWT), the Co-Au-Bi NICO deposit was selected as a first test site to characterize the heavy mineral and geochemical signature of IOCG±U deposits and derived glacial sediments and assess if some heavy minerals have a potential as indicator minerals for IOCG deposits in glaciated terrain. Bedrock and till samples, collected up-ice (background), proximal and down-ice from mineralization and host rocks, were analyzed to characterize their heavy mineral and geochemical signatures. Study of the heavy mineral signature of the NICO deposit area and overlying glacial sediments demonstrates that gold grain abundance, size and shape, as well as magnetite composition, have the best potential to fingerprint the IOCG mineralization. Relatively high concentrations of gold grains are found in surface tills collected over and near mineral showings of the NICO deposit area in comparison with those collected over barren host rocks and background terrain. Pristine gold grains indicating a local source and a short distance of glacial transport are mostly abundant close to mineralized zones indicating that documenting gold grain abundance, size, shape and fineness remains a valuable surface exploration method for gold-bearing IOCG deposits in the GBMZ. Iron oxide composition using preliminary discriminant diagrams shows some potential, namely with the Ni/(Cr+Mn) versus Ti+V plot. The non-ferromagnetic heavy minerals are either not chemically stable in surface glacial sediments (arsenopyrite, chalcopyrite, pyrite), not sufficiently coarse-grained (bismuthinite, tourmaline), not abundant enough in the mineralized bedrock (scheelite, molybdenite, cobaltite), or not sufficiently heavy (ferroactinolite). Although the Co-rich composition of arsenopyrite is possibly the strongest vector to Au-rich polymetallic mineralization in the study area, arsenopyrite is completely oxidized in surface tills. The development of indicator mineral methods, together with till geochemistry, will be further tested with detailed bedrock and drift sampling around the Sue-Dianne deposit in 2009.