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TitleConvergent margin Ni-Cu-PGE-Cr ore systems: U-Pb petrochronology and environments of Cu-PGE versus Cr-PGE mineralization in Alaskan-type intrusions
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LicencePlease note the adoption of the Open Government Licence - Canada supersedes any previous licences.
AuthorNixon, G T; Scoates, J S; Milidragovic, DORCID logo; Nott, J; Moerhuis, N; Ver Hoeve, T J; Manor, M J; Kjarsgaard, I M
SourceTargeted Geoscience Initiative 5: Advances in the understanding of Canadian Ni-Cu-PGE and Cr ore systems - Examples from the Midcontinent Rift, the Circum-Superior Belt, the Archean Superior Province, and Cordilleran Alaskan-type intrusions; by Bleeker, WORCID logo (ed.); Houlé, M G (ed.); Geological Survey of Canada, Open File 8722, 2020 p. 197-218, Open Access logo Open Access
PublisherNatural Resources Canada
Documentopen file
Mediaon-line; digital
RelatedThis publication is contained in Targeted Geoscience Initiative 5: Advances in the understanding of Canadian Ni-Cu-PGE and Cr ore systems - Examples from the Midcontinent Rift, the Circum-Superior Belt, the Archean Superior Province, and Cordilleran Alaskan-type intrusions
File formatpdf
ProvinceBritish Columbia
NTS92H/07; 92H/10; 94C/05; 94C/12
Lat/Long WENS-120.9333 -120.7667 49.5333 49.4000
Lat/Long WENS-125.5167 -125.5167 56.5667 56.4167
Subjectseconomic geology; geochronology; geochemistry; mineralogy; tectonics; Science and Technology; Nature and Environment; mineral exploration; exploration guidelines; mineral deposits; nickel; copper; chromium; magmatic deposits; sulphide deposits; ore mineral genesis; mineralization; ore controls; host rocks; bedrock geology; lithology; igneous rocks; mafic rocks; ultramafic rocks; intrusive rocks; tholeiites; dunites; chromitites; clinopyroxenites; structural features; faults; tectonic setting; tectonic history; plate margins; subduction; magmatism; intrusions; alaskan-type ultramafic complex; emplacement; crystallization; remobilization; metamorphism; deformation; radiometric dating; uranium lead dating; zircon; trace element geochemistry; modelling; mineral assemblages; alteration; fluid dynamics; laminations; schlieren; inclusions; dykes; zoning; bedding planes; foliation; schistosity; layering; Canadian Cordillera; Tulameen Intrusion; Polaris Intrusion; Stikinia; Quesnellia; Nicola Group; platinum group elements; geological contacts; Phanerozoic; Mesozoic; Jurassic; Triassic
Illustrationsgeoscientific sketch maps; photomicrographs; geochemical plots; bar graphs; photographs; tables; schematic models
ProgramTargeted Geoscience Initiative (TGI-5) Nickel-copper-PGE-chromium systems
Released2020 09 08
AbstractMagmatic Ni-Cu-PGE deposits hosted by ultramafic-mafic intrusions in convergent margin or supra-subduction/ post-subduction tectonic settings are becoming an increasingly important global resource. In the northern Cordillera, this class of intrusions is restricted to the accreted arc terranes of the continental margin of North America where the Alaskan-type subclass is particularly prevalent. This report describes recent research on the Tulameen and Polaris Alaskan-type intrusions in British Columbia that contain orthomagmatic Ni-Cu-PGE mineralization. Preliminary U-Pb geochronological results and trace element analyses of zircon from the Tulameen intrusion are interpreted using an integrated petrochronological approach to distinguish crystallization from post-crystallization events and to constrain the duration of magmatism. Magmatic Cu-PGE mineralization (predominantly chalcopyrite-bornite) in the Tulameen intrusion is hosted by hornblende-magnetite-bearing ultramafic rocks near its periphery. Preliminary results suggest that emplacement and crystallization of the Tulameen intrusion occurred ca. 204-205 Ma (latest Triassic), coincident with a 6 million year period centred on 205 Ma that produced the most important porphyry Cu-Au deposits in British Columbia. The Cu-PGE mineralization constitutes a unique deposit type for Alaskan-type intrusions and has some attributes in common with stratiform or 'reef-style' mineralization in tholeiitic layered intrusions. Magmatic Ni-Cu-PGE sulphides (mainly pyrrhotite, chalcopyrite, minor pentlandite) in the Early Jurassic (ca. 186 Ma) Polaris intrusion are hosted by the more evolved ultramafic and mafic rocks. Remobilized ultramafic cumulates form a distinctive component of both intrusions: plastically deformed and dismembered olivine-chromite cumulates are widely distributed in dunite, and what are interpreted as synmagmatic avalanche deposits are well exposed at Tulameen. The remobilization of pre-existing cumulate sequences is rationalized in terms of an open-system magma recharge model that accounts for some of the key textural features exhibited by ultramafic rocks in Alaskan-type intrusions.
Summary(Plain Language Summary, not published)
Key objectives of Phase 5 (2015-2020) of the Targeted Geoscientific Initiative (TGI) program of Natural Resources Canada and the Geological Survey of Canada were to generate new knowledge, methodologies, and models to enhance the exploration industry's ability to detect buried ore deposits and extensions of existing ore systems, and to provide models for targeting new deposit areas. This synthesis volume contains nine individual papers that discuss deposit scale to magmatic system fundamentals from various Canadian examples pertaining to the TGI-5 Ni-Cu-PGE-Cr project.

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