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Dating of quaternary basalts using the cosmogenic [sup 3]He and [sup 14]C methods with implications for excess [sup 40]Ar

Journal Article · · Geology; (United States)
Concordant radiocarbon and cosmogenic [sup 3]He dates of 3 and 11 ka on basalt flows and associated scoria deposits from the Zuni-Bandera volcanic field in New Mexico further substantiate published production rates and latitudinal and altitudinal corrections for [sup 3]He. Identical [sup 3]He concentrations in coexisting olivine and clinopyroxene confirm that these two minerals have very similar production rates. A cosmogenic [sup 3]He date of 57 ka on another flow is concordant with a U-series date and is younger than two K-Ar dates, suggesting that this flow contains excess [sup 40]Ar. This excess [sup 40]Ar is also evident in gases released by vacuum crushing of olivine-clinopyroxene fractions from all three flows. 27 refs., 3 figs., 3 tabs.
OSTI ID:
5095597
Journal Information:
Geology; (United States), Journal Name: Geology; (United States) Vol. 22:2; ISSN 0091-7613; ISSN GLGYBA
Country of Publication:
United States
Language:
English