GeoFile 2010-4: Carbonate-hosted Sulphide and Nonsulphide Pb-Zn Mineralization, Cariboo Terrane, BC, Canada
View GeoFile 2010-4 (PDF, 8 MB)
Under 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 wallrock replacement nonsulphide base metal deposits. Nonsulphide deposits were the main source of zinc in the 19th century. Due to the 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.
Cariboo Zinc property provides excellent examples of Zn-Pb sulphides and “mixed ores” (rocks consisting of sulphide and nonsulphide minerals). Mineralization is concentrated along a northwest-trending, dolomitic belt (8 km long). It consists of pervasive fine-grained sulphide and nonsulphide disseminations and 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 are Canopener, DeBasher, Flipper Creek, Dolomite Flats, Main, Gunn and Que. In most exposed 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 metal-bearing minerals.
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