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| | Regional Metallogeny and Geochronology of the Bridge River District
(NTS 92O, 92J, 92I)
- Craig Hart, University of Western Australia
The Bridge River mineral district in southwestern British Columbia is well-known for the Bralorne-Pioneer orogenic gold system that yielded over 4.1 million ounces of gold during its long history (1897-1971). Gold was also produced from a few other small mines, but this area has recently seen an increase in exploration activity. Throughout the broader district, between the Coast Plutonic Complex and the Yalakom Fault, there are a large number of small stibnite, mercury and polymetallic vein occurrences, many of which have been interpreted as epithermal in origin, or related to Eocene magmatism.
A regional scale program of data compilation, field examinations, and sampling, supported with precise age dating and filling in gaps in fluid and stable isotope geochemistry, will allow assessment of appropriate deposit models and provide confidence in exploration programs. This project will be done in concert with exploration companies active in the area, and participation from recognized experts (including the BCGS and GSC) will be encouraged.
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| Phone: 604-662-4147 Fax: 604-662-4107 Email: | |
Orogenic gold vein deposits are among the most lucrative deposit type to mine, characteristically with high gold grades, focused mineralization, large vertical extents, easy metallurgy, and reasonably small environmental footprints. The hydrothermal systems that form these deposits span a wide range of crustal levels, but this crustal-continuum concept for Orogenic gold deposits hasn't been well-appreciated or applied in exploration. Deposits rich in antimony and mercury are traditionally considered to be associated with, typically small, epithermal styles of mineralization, but there is an increased recognition that some of these deposits may represent the epizonal portions of potentially larger orogenic gold deposits.
Within the diversity of mineralization in the region, specific aspects, such as age, structural setting, crustal level and fluid types can be used to determine the most appropriate gold deposit model and thereby assess prospectivity and effective exploration targeting. In simple language, "Which occurrences are worthy of aggressive exploration efforts". Although the few age dates that exist on mineralization are generally Late Cretaceous, the data aren't precise enough to allow comparisons between deposits, or with magmatism such as the Bendor plutonic suite. Additionally, most dates are by the K-Ar method and are likely variably reset by younger thermal events. Other data, such as mapping, geological and descriptive information, and fluid and stable isotope data, are generally good, but require new sampling and analysis, compilation, and interpretation.