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TitreTill mineralogy and geochemistry in the Highland Valley Cu-Mo porphyry district, south-central British Columbia
AuteurPlouffe, A; Ferbey, T; Bustard, A L
SourceGeological Association of Canada-Mineralogical Association of Canada, Excursion Guide vol. 39, 2016 p. 73
LiensOnline - En ligne
Année2016
Séries alt.Secteur des sciences de la Terre, Contribution externe 20160025
ÉditeurAssociation géologique du Canada
RéunionGAC-MAC Margins Through Time; Whitehorse, YT; CA; juin 1-3, 2016
Documentpublication en série
Lang.anglais
Mediapapier
Formatspdf
ProvinceColombie-Britannique
SNRC92I/11
Lat/Long OENS-121.5000 -121.0000 51.0000 50.5000
Sujetsdensités des minerais; gisements minéraux; géochimie du till; échantillons de till; cuivre porphyrique; gisements porphyriques; éléments d'indice; minéralisation; erosion glaciaire; topographie glaciaire; Batholite de Guichon Creek ; géochimie; géologie générale
ProgrammeÉtude des gîtes porphyriques, Initiative géoscientifique ciblée (IGC-4)
Résumé(disponible en anglais seulement)
The Highland Valley district includes five economic Cu-Mo porphyry deposits hosted in the Guichon Creek batholith of south-central British Columbia. Between 1962 and 2013, 1615 million tonnes of ore grading 0.4%Cu and 0.01% Mo have been processed at the Highland Valley Copper mine (HVC) representing one of the largest Cu deposits in Canada. The HVC region is characterized by an extensive cover of glacial sediments with a predominance of tills from the Late Wisconsinan Fraser Glaciation. Surface landforms include drumlins, flutings and crag-and-tails which indicate ice flow to the south to southeast. A total of 97 subglacial till samples were collected within a 1000 km2 area centered on HVC with the objective of identifying the geochemical and mineralogical footprint of the porphyry mineralization in the surficial sediments. Samples were processed for indicator minerals in the medium to very coarse sand-sized fraction (0.25-2 mm) and for geochemical analyses of the silt plus clay- (<0.063 mm) and clay-sized (<0.002 mm) fractions. Results show that geochemically, the Cu-Mo mineralization is well reflected in till with high Cu and Mo concentrations (e.g. >1500 ppm Cu and >20 ppm Mo in the silt plus clay) close to mineralized zones progressively decreasing to background concentrations (<200 ppm Cu and <1.5 ppm Mo in the silt plus clay) approximately 20 km to the southeast. Similarly, Al2O3 content of till varies from >17% near mineralized zones and drops to background concentrations <16% 10 km to the southeast. The high Al content of till near mineralization is interpreted to be derived from phyllosilicate alteration minerals associated with mineralization. Similar to the Cu concentrations, the number of chalcopyrite grains in till (0.25-0.5 mm; >3.2 specific gravity) is highest (>100 grains/10kg) near mineralized zones and decreases to <10 grains/10kg at about 10 km to the southeast. Scheelite and barite are more abundant in till near mineralization compared to background region and therefore, could be used as porphyry indicator minerals in the Highland Valley district. The regional geochemical and mineralogical footprint measured in till at Highland Valley is interpreted to result from glacial erosion of a cluster of economic and sub-economic mineralized zones and detrital glacial dispersal up to 20 km to the southeast. This project was a collaborative effort between the British Columbia Geological Survey and the Geological Survey of Canada supported by the Targeted Geoscience Initiative-4 (TGI-4) and the Canadian Mining Innovation Council (Cu Footprint Project).
Résumé(Résumé en langage clair et simple, non publié)
Nous démontrons dans cette présentation que des zones dans la roche en place enrichies en cuivre et couvertes par des sédiments glaciaires peuvent être détectées en analysant la minéralogie et la géochimie du sédiment glaciaire. Certaines de ces zones représentent des gisements économiques où l'on fait l'extraction du cuivre et du molybdène. Cette méthode d'exploration minérale sera communiquée à l'industrie à la conférence.
GEOSCAN ID298716