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TitreExploring for lead and zinc using indicator minerals with stream silt and water geochemistry in the Canadian Arctic Islands: an example from Victoria Island, Northwest Territories
AuteurMcCurdy, M W; Rainbird, R H; McNeil, R J
SourceNew Frontiers for Exploration in Glaciated Terrain, PDAC 2013 short course; 2013 p. 65-70
Séries alt.Secteur des sciences de la Terre, Contribution externe 20120418
RéunionNew Frontiers for Exploration in Glaciated Terrain workshop, PDAC 2013 International Convention; Toronto; CA; mars 1, 2013
Référence reliéeCette publication est reliée à McCurdy, M; McCurdy, M; Rainbird, R; Rainbird, R; McNeil, R; McNeil, R; (2013). Exploring for lead and zinc using indicator minerals with stream silt and water geochemistry in the Canadian arctic islands: an example from Victoria Island, Northwest Territories, New frontiers for exploration in glaciated terrain, Commission géologique du Canada, Dossier public 7374
ProvinceTerritoires du Nord-Ouest
SNRC87G/01; 87G/08; 87G/09; 87G/16; 87H
Lat/Long OENS-117.0000 -112.0000 73.0000 71.0000
Sujetsgîtes minéralogiques; méthodes d'exploration; prospection minière; exploration de dépôts glaciaires; géochimie des dépôts glaciaires; tills; géochimie du till; éléments d'indice; dépôts glaciaires; topographie glaciaire; elements glaciaires; antecedents glaciaires; transport des sediments; méthodes d'échantillonage; techniques d'échantillonage; analyses géochimiques; lithologie des galets; gîtes volcanogènes; sulfures; gîtes sulfureux; plomb; zinc; analyses spectrométriques; fluorescence aux rayons x; méthodes de fluorescence aux rayons x; géochimie des sédiments de cours d'eau; géochimie de l'eau de cours d'eau; silts; géologie économique; géologie des dépôts meubles/géomorphologie; hydrogéologie; Cénozoïque; Quaternaire
Illustrationslocation maps; plots
ProgrammeBases de données couvrant les trois territoires (minéraux indicateurs), GEM : La géocartographie de l'énergie et des minéraux
Résumé(disponible en anglais seulement)
Exploring for minerals in the Arctic is expensive and risky. In many areas the background knowledge of bedrock and surficial geology is limited, making spending decisions even more challenging. However, access to huge areas of the north will continue to improve throughout this century, and new methods and technologies must be developed or adapted for exploration in these unique and potentially mineral-rich areas.
The former National Geochemical Reconnaissance program, a federal-provincial-territorial initiative to map the surficial geochemistry of Canada using stream and lake sediments and waters, largely avoided surveys over Palaeozoic carbonate terrain because of the reduced mobility of many elements of interest and the limited detection levels of methods available at the time. However, given the large areas of Palaeozoic carbonate cover over much of the land north of the Arctic Circle in Canada, and the potential in these rocks for economic Pb-Zn mineralization, it is essential to develop regional methods of exploration using surficial geochemical surveys.
A recent activity funded under the Geo-Mapping for Energy and Minerals program on Victoria Island, Northwest Territories, included regional stream sediment and water sampling and the identification of indicator minerals in the heavy mineral fraction of stream sediments. Previous geochemical exploration on Victoria Island focused on the nickel, copper and platinum potential in gabbro-diabase sills and dykes overlying the Neoproterozoic Shaler Supergroup. However, regional geochemical data clearly outline two areas within Shaler Supergroup marine carbonate and evaporate units with Pb-Zn potential.
The regional geology of Victoria Island is favourable for the formation of Pb-Zn mineralization, with regard to age, host rocks and structural features. Additional support for potential Pb-Zn mineralization on Victoria Island is based on comparisons with established former mining camps, including Polaris, Pine Point and Nanisivik, as well more recent data from Bathurst Island, Pine Point, and Prairie Creek.
The regional geochemical survey on Victoria Island was carried out over two field seasons in 2010 and 2011. Geochemical surveys at Prairie Creek and Pine Point using similar methods were compared with the results from Victoria Island, and archive bulk sediment samples from Bathurst Island were reanalyzed. Selected sphalerite and galena grains identified in the heavy mineral fraction of bulk sediments were analyzed for sulphur and lead isotopes.
Reductions in the cost of analyzing sulphur isotopes in sphalerite and Pb isotopes in galena make isotope fingerprinting a practical method to establish the provenance of mineral grains in heavy mineral samples. Comparison of Pb and S isotope data for Victoria Island with other areas suggests that the sphalerite and galena in the heavy mineral fraction are from a single source.
Pb, and to a lesser extent Zn, are normally insoluble under high pH conditions; however, in watersheds where sphalerite and galena were identified in heavy mineral concentrates, despite pH values exceeding 8, both Zn and Pb were measured in stream waters. Interpretation of water data depends on understanding the reactions of Pb and Zn sulphides to changes in redox conditions, sulphur species and adsorption by Fe and Mn hydroxides. Examples from recent studies at Pine Point and Prairie Creek are used to illustrate the geochemistry of surface waters on Victoria Island and to show that surface waters can be an effective and relatively inexpensive sample medium for Pb-Zn exploration in northern carbonate terrains.