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TitleDiscovering the next generation of porphyry Cu deposits in glaciated landscapes
AuthorPlouffe, A; Kobylinski, C; Hattori, K; Ferbey, T
SourceResources for Future Generations 2018, Vancouver, Canada, technical program; 1733, 2018 p. 1
LinksOnline - En ligne (pdf, 79 KB)
Alt SeriesNatural Resources Canada, Contribution Series 20170388
PublisherGeological Association of Canada
MeetingRFG 2018 - Resources for Future Generations; Vancouver, BC; CA; 16-21 June 2018
DocumentWeb site
Mediaon-line; digital
File formatpdf
Subjectseconomic geology; surficial geology/geomorphology; geochemistry; mineralogy; mineral deposits; porphyry deposits; copper; mineral exploration; exploration methods; drift prospecting; glacial deposits; tills; sediment dispersal; dispersal patterns; till geochemistry; mineralogical analyses; magmatism; alteration; cerium geochemistry; isotopic studies; zircon; chalcopyrite; epidote; mineral zoning; inclusions; dispersal trains; rare earth element analyses
ProgramTargeted Geoscience Initiative (TGI-5), Porphyry systems
Released2018 06 01
AbstractThe next generation of porphyry Cu deposits to be discovered is unlikely to be exposed at surface. In glaciated landscape where outcrop is rare, they are most likely covered by unconsolidated sediments. Till geochemistry and mineralogy footprint studies were completed near four porphyry deposits of British Columbia, Canada to develop exploration methods in glaciated landscapes. Dispersal trains in till defined by matrix geochemistry (e.g. Cu) and chalcopyrite abundance extend several kilometres down-ice from mineralization at these four sites. Results indicate that where Cu mineralization was exposed to glacial erosion, till geochemistry and mineralogy reflect the presence of the mineralized zones. To improve discovery of covered deposits and deeply buried mineralization not exposed to glacial erosion, we are testing magmatic and alteration minerals as potential indicators of Cu porphyry mineralization. The objective is to investigate the composition of minerals related to mineralization and to map the abundance and detectability of these minerals in till. Previous studies have indicated that high Ce4+/Ce3+ ratios within magmatic zircon are indicative of oxidizing conditions favorable for the formation of porphyry deposits. For example, zircon from mineralized rocks at the Gibraltar Cu-Mo porphyry deposit, in the Mine phase of the Granite Mountain batholith (Late Triassic), yield higher Ce4+/Ce3+ values (>200) compared to non-mineralized phases (ca. 100). Zircon grains indicative of oxidized magmatic conditions have been identified in till <1 km down-ice from economic mineralization at that site. The high abundance of epidote in till near Cu porphyry mineralization is significant at the four study sites. Epidote composition in till and bedrock at Gibraltar suggests that the high abundance of epidote in till near mineralization is likely derived from the contact zone of the intrusion with country rocks. This conclusion is based on REE content, Fe zoning, and inclusions in epidote.
Summary(Plain Language Summary, not published)
This poster will present new research results on the composition of specific minerals which will allow us to discover deposits of copper not exposed at surface. The objective is to identify minerals with a copper mineralization signature in glacial sediments. The presence of these minerals would be a clue that copper mineralization occurs beneath the glacial sediment cover.