Abstract

K-feldspar veins give a Rb/Sr isochron of 200 + or - 2 m.y., in good agreement with the K/Ar date of 198 + or - 8 m.y. for the parent batholith. The low initial Sr-87/Sr-86 ratio, 0.7037 + or - 0.0002, implies a mantle source for batholith and ore similar to that of recent basalt. Sulfur isotope data suggest that mantle-type sulfur became dominant over country-rock sulfur as mineralization progressed. Similarly C and O determinations indicate little or no magmatic C during early skarn formation, and a magmatic, non-limestone source for the carbonate associated with late mineralization.

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