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TitleCarbonate-hosted sulphide and nonsulphide Pb-Zn mineralization, Cariboo Terrane, BC, Canada
AuthorParadis, S; Simandl, G J; Bradford, J; Leslie, C; Brett, C
SourceBritish Columbia Geological Survey, Geofile 2010-4, 2010, 1 sheet (Open Access)
LinksOnline - En ligne
Alt SeriesEarth Sciences Sector, Contribution Series 20100106
Mediaon-line; digital
ProvinceBritish Columbia
NTS82E; 82F; 82G; 82J; 82K; 82L; 82M; 82N; 93A; 93G; 93H; 93I; 93J; 93K; 93N; 93O; 94A; 94B; 94C; 94F; 94G
Lat/Long WENS-128.0000 -114.0000 58.0000 49.0000
Subjectseconomic geology; mineral deposits; mineral occurrences; mineralization; sulphides; lead; zinc; carbonates; carbonate rocks; Kootenay Arch; Kootenay Terrane; Cariboo Terrane
Illustrationslocation maps; photographs
ProgramTargeted Geoscience Initiative (TGI-3), 2005-2010, Southern Cordillera TGI-3
AbstractUnder favourable geological, climatic, topographic and hydrological conditions, the weathering of carbonate-hosted, sulphide deposits may result in the formation of economically significant direct replacement and/or wallrock replacement nonsulphide base metal deposits (Hitzman et al, 2003; Simandl and Paradis, 2009; Paradis et al. 2010).
Nonsulphide deposits were the main source of zinc in the 19th century. Due to the development of differential flotation and other metallurgical innovations during the early 20th century, the interest of explorationists shifted to sulphide ores. For a variety of environmental and economic reasons, nonsulphide deposits are again representing attractive exploration targets; however, they are commonly overlooked. The discovery rate of nonsulphide deposits in British Columbia will depend largely on the ability of the explorationists to recognize nonsulphide zinc and lead minerals, and to understand the mobility of base metals in near surface environments and the parameters that cause their precipitation as base metal carbonates, silicates or oxides.
The Cariboo terrane of central BC (Figures 1 and 2) hosts several well known base metal mineral deposits, including polymetallic Ag-Pb-Zn (±Au) veins, carbonate and sediment-hosted massive sulphides [i.e., Zn-Pb Mississippi Valley-type (MVT), sedimentary exhalative Zn-Pb-Ag (SEDEX), Besshi-type massive sulphides (VHMS)], and gold placers. Carbonate-hosted nonsulphide base metal deposits are commonly overlooked.
Excellent examples of Zn-Pb sulphides and "mixed ores" (rocks consisting of sulphide and nonsulphide minerals) crop out on the Cariboo Zinc property (Figures 2 and 3). Mineralization is concentrated along a favourable northwest-trending, dolomitic belt about 8 km long (Figure 3). It consists of pervasive fine-grained sulphide and nonsulphide disseminations and aggregates forming pods and masses, sulphide- and nonsulphide-bearing quartz (±calcite) veins, and crackle breccias. Sulphides are galena, sphalerite, and trace amounts of pyrite. Nonsulphides are smithsonite, hemimorphite, cerussite, hydrozincite, and possibly anglesite. The main showings, from west to east, are Canopener, DeBasher, Flipper Creek, Dolomite Flats, Main, Gunn and Que (Figures 4, 5, 6, 7, 8 and 9).
In most occurrences, the spatial continuity and/or the close spatial relationships in combination with morphological similarities between sulphide and associated nonsulphide zones suggest direct-replacement of sulphides by nonsulphide base-metalbearing minerals. The main exposure at the Gunn showing is an excellent example of a carbonate-hosted, nonsulphide, base-metal deposit formed by the direct replacement of sulphides.
The area was covered by detailed gravity survey (Luckman, 2008). The determination of physical characteristics of mineralized (Pb-Zn sulphide and nonsulphide) rocks will be useful for the design of future exploration programs and for re-interpretation of existing gravity surveys. Mineralogical, geochemical and isotope studies are underway.