| Titre | Detecting buried porphyry Cu mineralization in a glaciated landscape: a case study from the Gibraltar Cu-Mo deposit, British Columbia, Canada |
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| Auteur | Plouffe, A ;
Kjarsgaard, I M; Ferbey, T; Wilton, D H C; Petts, D; Percival,
J B; Kobylinski, C; McNeil, R |
| Source | Economic Geology 2022 p. 1-24, https://doi.org/10.5382/econgeo.4891  Accès ouvert |
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| Année | 2022 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20210117 |
| Éditeur | MDPI |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.5382/econgeo.4891 |
| Media | papier; en ligne; numérique |
| Formats | pdf; html |
| Province | Colombie-Britannique |
| Lat/Long OENS | -139.5000 -112.0000 60.0000 48.0000 |
| Sujets | minéralogie; Sciences et technologie |
| Illustrations | cartes de localisation; photographies; diagrammes; tableaux |
| Programme | Initiative géoscientifique ciblée (IGC-6) Systèmes minéralisés |
| Diffusé | 2022 02 01 |
| Résumé | (disponible en anglais seulement)
At the Gibraltar porphyry Cu-Mo deposit in south-central British Columbia, geochemical and mineralogical anomalies in till, around a cluster of mineral
occurrences, form amoeboid dispersal patterns controlled by three phases of ice movements. The dispersal patterns defined by elevated concentrations of ore (Cu, Mo) and pathfinder (Ag, Zn) elements, and alteration oxides (Al2O3, K2O) in the till
matrix (clay and silt plus clay fractions) extend over areas of 6 to 36 km2 and are centered on the main economic mineralization. The abundances of sulfides (chalcopyrite, pyrite), sulfate (jarosite) and silicates (titanite, epidote) in the till were
determined optically in the 0.25-0.50 mm size range, and the 2.8-3.2 and >3.2 specific gravity (SG) fractions, and by mineral liberation analysis (MLA) and scanning electron microscopy (SEM) in the 0.125-0.180 mm and >3.2 SG fraction. The dispersal
trains are defined by the high abundances of these minerals derived from the mineralization and associated oxidized and alterated zones. The areal extent of these mineralogical anomalies in till reaches approximately 30 km2 for chalcopyrite, 62 km2
for jarosite, and up to 136 km2 for epidote. Epidote grains in till with a trace element composition of >10 ppm As, >4 ppm Sb, <200 ppm Sigma-REE, <45 ppm Y, <100 ppm Sc + Cr + Y, and/or <2 ppm Th + Hf are interpreted as being principally derived
from intrusive rocks or the hydrothermal alteration associated with the porphyry mineralization at the Gibraltar deposit. Rare epidote grains with >30 ppm Cu are interpreted to be related to porphyry Cu mineralization and are detected in till at up
to 7 km down-ice from the economic mineralization. A limited number of zircon grains from till yielded Ce/Nd ratios >19 which might relate to the high oxidation state and potentially the ore fertility potential of the intrusion. Till geochemistry and
mineralogy along with geochemical analyses of specific minerals such as epidote and zircon represent an efficient method to establish porphyry Cu mineralization potential in terrains covered with glacial sediments. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Les gîtes porphyriques se retrouvent dans des roches intrusives (comme du granite) et contiennent d'importante quantité de cuivre. La découverte
de nouveaux gisements de cuivre, un conducteur à faible coût, est primordiale pour développer une économie verte à base d'énergie renouvelable telle que l'hydro-électricité. Cet article présente des données sur la géochimie et la minéralogie des
sédiments glaciaires qui faciliteront la découverte de gisements de cuivre enfouis sous des sédiments de la dernière glaciation. |
| GEOSCAN ID | 328412 |
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