NEW K-Ar ISOTOPIC AGES OF EPITHERMAL ALTERATION FROM THE TOODOGGONE RIVER AREA, BRITISH COLUMBIA

This report presents three new potassium-argon isotopic age determinations of minerals associated with epithermal alteration from the Toodoggone district, north-central British Columbia. The Toodoggone area has received extensive exploration attention over the past 10 years. In addition to a former goldsilver producer (Baker mine), the district contains a major new gold-silver mine in development (Lawyers), several gold deposits undergoing final feasibility studies (Bonanza, BV and Thesis III), and numerous other precious metal prospects. Most of these deposits exhibit characteristics typical of epithermal mineralization. Schroeter (19X2) and Schroeter er al. (1986) have demonstrated that alteration associated with some of the occurrences is Early to Middle Jurassic in age. Further, Clark and Williams-Jones (1987, 1988) have suggested that gold-silver deposits in the Toodoggone area are restricted to mid-Toarcian (approximately 190 Ma) and older rocks, and represent a district-wide period of alteration and mineralization. The objective of the current study is to provide additional estimates of the age of epithermal alteration and mineralization in the Toodoggone district. The new data will contribute to ongoing research on the gold-silver metallogeny of the camp, to specific ore deposit genesis studies, and to the placement of the mineralization within a lithotectonic framework relevant to the exploration community.