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TitleVariation in vein mineralogy and mineral chemistry around the Marathon Cu-Pd deposit, Ontario: insights into the development of an exploration tool
LicencePlease note the adoption of the Open Government Licence - Canada supersedes any previous licences.
AuthorBrzozowski, M J; Samson, I M; Gagnon, J E; Linnen, R L; Good, D J; Ames, D EORCID logo; Flemming, R L
SourceTargeted Geoscience Initiative 4: Canadian nickel-copper-platinum group elements-chromium ore systems -- fertility, pathfinders, new and revised models; by Ames, D EORCID logo (ed.); Houlé, M G (ed.); Geological Survey of Canada, Open File 7856, 2015 p. 245-255, Open Access logo Open Access
PublisherNatural Resources Canada
Documentopen file
Mediaon-line; digital
RelatedThis publication is contained in Targeted Geoscience Initiative 4: Canadian nickel-copper-platinum group elements-chromium ore systems -- fertility, pathfinders, new and revised models
File formatpdf
NTS42D/08; 42D/09
Lat/Long WENS -86.5000 -86.0000 47.7500 47.2500
Subjectsgeochemistry; igneous and metamorphic petrology; copper; palladium; ore mineral genesis; metallogeny; vein deposits; mineralization; chlorite; petrographic analyses; major element geochemistry; trace element geochemistry; alteration; modelling; Superior Province; Marathon deposit; Two Duck Lake Intrusion
ProgramTargeted Geoscience Initiative (TGI-4) Mafic-Ultramafic Ore Systems
Released2015 06 22; 2023 03 17
AbstractThe 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.
Summary(Plain Language Summary, not published)
The Targeted Geoscience Initiative (TGI-4) is a collaborative federal geoscience program that provides industry with the next generation of geoscience knowledge and innovative techniques to better detect buried mineral deposits, thereby reducing some of the risks of exploration. This volume summarizes 22 research activities completed under the TGI-4 Ni-Cu-PGE-Cr ore systems project that focused on revised and new geologic models for Ni-Cu-PGE, PGE-Cu and Cr deposits, innovative techniques for determining potential fertility of intrusion (Ni-Cu-PGE), and defining pathfinders for Ni-Cu-PGE mineralization.

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