Abstract

The Beaverdell silver, lead, and zinc vein camp is in south-central British Columbia. Granodiorite of the Jurassic(?) Westkettle batholith underlies much of the area, and has been intruded by stocks of Tertiary quartz monzonite including the Beaverdell stock. Remnants of pendants and (or) screens of metamorphosed sediments and volcanics of the Permian(?) Wallace Formation are contained in the granodiorite. Silver vein mineralization, characterized by the Beaverdell deposits on Wallace Mountain, are mainly within the Westkettle batholith. Gold mineralization, characterized by the Carmi mine, is commonly found near the contact of Westkettle granodiorite and Wallace Formation.Geological information, including K–Ar dating, provides constraints for the evaluation of galena-lead isotope data. Plots of the galena-lead analyses on 206Pb/204Pb versus 207Pb/204Pb and 206Pb/204Pb versus 208Pb/204Pb diagrams fall into two distinct clusters, group A and group B. Group A is characterized by Carmi gold mineralization and group B includes Beaverdell silver mineralization. Three geological models for the generation of the lead in these deposits are evaluated based on three possible ages of mineralization, viz. Permian (0.27 Ga), Jurassic (0.15 Ga), and Tertiary (0.05 Ga). However, we favour the model that indicates that group A and group B deposits formed at different times, under markedly different geological conditions. Specifically, group A vein mineralization is probably Jurassic in age and formed as a result of the intrusion of the mesozonal Westkettle batholith, and group B vein mineralization is likely Tertiary in age and is genetically linked to Tertiary intrusions such as the Beaverdell stock.Exploration for the two specific types of deposits in the Beaverdell area, represented by groups A and B, can be guided by galena-lead isotope analyses, because galena-lead isotopes for group A are substantially different from those for group B deposits.

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