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TitreVariation in vein mineralogy and mineral chemistry around the Marathon Cu-Pd deposit, Ontario: insights into the development of an exploration tool
TéléchargerTéléchargement (publication entière)
AuteurBrzozowski, M J; Samson, I M; Gagnon, J E; Linnen, R L; Good, D J; Ames, D E; Flemming, R L
SourceTargeted Geoscience Initiative 4: Canadian nickel-copper-platinum group elements-chromium ore systems -- fertility, pathfinders, new and revised models; par Ames, D E (éd.); Houlé, M G (éd.); Commission géologique du Canada, Dossier public 7856, 2015 p. 245-255, (Accès ouvert)
ÉditeurRessources naturelles Canada
Documentdossier public
Mediaen ligne; numérique
Référence reliéeCette publication est contenue dans Ames, D E; Houlé, M G; (2015). Targeted Geoscience Initiative 4: Canadian nickel-copper-platinum group elements-chromium ore systems -- fertility, pathfinders, new and revised models, Commission géologique du Canada, Dossier public 7856
SNRC42D/08; 42D/09
Lat/Long OENS -86.5000 -86.0000 47.7500 47.2500
Sujetscuivre; palladium; genèse des minerais; métallogénie; gisements filoniens; minéralisation; chlorite; analyses pétrographiques; géochimie des éléments majeurs; géochimie des éléments en trace; altération; établissement de modèles; Province de Superior ; géochimie; pétrologie ignée et métamorphique
ProgrammeÉtude des gîtes magmatiques de Ni-Cu-EPG, Initiative géoscientifique ciblée (IGC-4)
Diffusé2015 06 22
Résumé(disponible en anglais seulement)
The Marathon Cu-Pd deposit (125 Mt at 0.26% Cu, 0.72 ppm Pd, 0.25 ppm Pt, and 0.08 ppm Au) is hosted within the Two Duck Lake Intrusion (TDLI), a late-stage phase of the Eastern Gabbro in the Coldwell Complex. Late-stage chlorite±calcite veins are present in and around the Marathon deposit, indicating subsolidus movement of fluids throughout mineralized and barren rocks. The hypothesis to be tested is did fluids migrating upwards through mineralized rock mobilize metals into overlying barren rock and was this movement recorded in the chemistry of vein minerals? Chlorite- and calcite-bearing veins were collected from drillholes throughout the deposit. The drill-core samples contain veins hosted in variably mineralized and barren host rocks. Chlorite, the dominant phase, occurs as very fine-grained, bladed crystals in massive, radiating, or aligned aggregates. The veins also contain minor saponite, talc, serpentine, and/or amphibole. Mineral chemistry data from energy- and wavelength-dispersive spectroscopy indicate that the Fe/Mg ratio in chlorite (chamosite to clinochlore) is highly variable, and varies as a function of host-rock type.
Laser ablation ICP-MS analyses were carried out on 52 chlorite samples collected throughout the deposit and barren host rocks. Transition metals were detected in all chlorite veins, whereas metalloids were only detected in a subset of samples. Titanium, Cr, Mn, Zn, and metalloid concentrations do not correlate with host-rock type. Transition metal concentrations in vein chlorite that crosscuts plagioclase, pyroxene, and pyrrhotite are comparable; however, chlorite in veins that occur in magnetite, altered olivine, and chalcopyrite have distinctive transition metal signatures (e.g. significantly higher Ti and V concentrations in veins hosted by magnetite), indicating that chlorite chemistry was controlled on a very local scale. Cobalt, Ni, and Cu concentrations are greater above mineralization than within mineralization. The Mn concentrations in chlorite increase linearly towards mineralization, whereas Co, Ni, and Zn decrease. When employing chlorite chemistry as a vector to mineralization, grain-scale variations in chlorite must be considered. Our results show that when these small-scale controls on chlorite composition are recognized, the chemistry of chlorite can be a successful exploration tool.