Abstract

K-Ar age determinations indicate that magmatism and molybdenite mineralization are indistinguishable within an experimental error of 0.8 m.y. These ages of 22.3-23.5 m.y. fall in the mid-Tertiary pulse of magmatism recognized in the southwestern United States, and agree with dates reported on other molybdenum properties in the Rocky Mountain Province. Sulfur isotopic measures suggest that at least some of the gypsum is hypogene. The Sr-87/Sr-86 ratios in a whole-rock sample of the Mine Aplite yield an initial ratio of 0.7069 similar to previously reported ratios for volcanic and intrusive rocks in the western United States.

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