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Age measurements of potassium-bearing sulfide minerals by the 40Ar/39Ar technique

G.K. Czamanske·M. A. Lanphere·Richard C. Erd·M.C. Blake
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Abstract

K-Ar ages have been determined for sulfide minerals for the first time. The occurrence of adequate amounts of potassium-bearing sulfides with ideal compositions K 3 Fe 10 S 14 (∼10 wt.% K) and KFe 2 S 3 (∼16 wt.% K) in samples from a mafic alkalic diatreme at Coyote Peak, California, prompted an attempt to date these materials. K 3 Fe 10 S 14 , a massive mineral with conchoidal fracture, gives an age of 29.4 ± 0.5m.y.( 40 Ar/ 39 Ar) , indistinguishable from the 28.3 ± 0.4m.y.( 40 Ar/ 39 Ar) and 30.2 ± 1.0m.y. 8 (conventional K-Ar) ages obtained for associated phlogopite (8.7 wt.% K). KFe 2 S 3 , a bladed, fibrous sulfide, gives a younger age, 26.5 ± 0.5m.y.( 40 Ar/ 39 Ar) , presumably owing to Ar loss.

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G.K. Czamanske, M. A. Lanphere, Richard C. Erd, M.C. Blake. 1978. Age measurements of potassium-bearing sulfide minerals by the 40Ar/39Ar technique. https://doi.org/10.1016/0012-821x(78)90079-1

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