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TitleAlteration vectors to IOCG mineralization from uncharted terranes to deposits
AuthorCorriveau, L; Williams, P J; Mumin, A H
SourceExploring for iron oxide copper-gold deposits: Canada and global analogues; by Corriveau, L (ed.); Mumin, H (ed.); Geological Association of Canada, Short Course Notes no. 20, 2010 p. 89-110
Alt SeriesEarth Sciences Sector, Contribution Series 20090318
ProvinceNorthwest Territories
NTS85N; 86C; 86D; 86E; 86F; 86K; 86L
AreaCloncurry; Queensland; Great Bear Lake; Lac la Martre; Hottah Lake; Canada; Australia
Lat/Long WENS-119.0000 -116.0000 67.0000 63.0000
Subjectseconomic geology; mineral deposits; mineral occurrences; iron oxides; copper; gold; mineralization; hydrothermal alteration; alteration; hydrothermal deposits; Great Bear Magmatic Zone
Illustrationslocation maps; photographs
ProgramIron-oxide Copper-gold (IOCG) / Multiple Metals - Great Bear Lake (NWT), GEM: Geo-mapping for Energy and Minerals
ProgramSecure Canadian Energy Supply
ProgramTargeted Geoscience Initiative (TGI-3), 2005-2010
AbstractDistinctive, diagnostic, district- to deposit-scale sodic, calcic-ferroan, and potassic-ferroan hydrothermal alteration and associated breccia characterize polymetallic iron oxide copper-gold (Co-Ag-Bi-REE-U) (IOCG) deposits worldwide, including those of the Cloncurry district in Australia and the Great Bear Magmatic Zone in Canada. Intense and extensive early Na to Ca-Fe alteration zones demarcate areas of interest at the regional scale and may form the immediate host of magnetite-apatite deposits. Hydrothermal systems that evolve to high temperature K-Fe (magnetite-K-feldspar/biotite), skarn (clinopyroxene/garnet) and/or lower temperature K-Fe-H2O-CO2 (sericite/K-feldspar-hematite-chlorite-carbonate) alteration have the capacity to produce significant polymetallic deposits, including uranium-bearing ones. Textural pseudomorphing to severe and extensive texture-destructive recrystallization of precursor rocks is observed within IOCG systems and leads to extremely varied alteration textures that can make it difficult to fully appreciate and even identify alteration zones during mapping. In contrast, the evolution of alteration types and brecciation from regional to deposit scale is highly predictable, even though the distribution and the exact paragenesis of alteration are not. The zoning model that emerges from commonalities in IOCG alteration and breccia development provides effective and predictive geological and geophysical mapping and exploration tools for and vectors to IOCG mineralization applicable to uncharted prospective terranes and known IOCG districts.