A 13 ± 3 ka age determination of a tholeiite,Pinacate volcanic field,Mexico, and improved methods for Ar/Ar dating of young basaltic rocks |
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| Authors: | Brent D Turrin James T Gutmann Carl C Swisher III |
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| Institution: | 1. Department of Geological Sciences, Rutgers University, Piscataway, NJ 08854, USA;2. Department of Earth and Environmental Sciences, Wesleyan University, Middletown, CT 06459, USA |
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| Abstract: | Among the youngest lava flows of the Pinacate volcanic field, Sonora, Mexico, is a large outpouring of tholeiite, the Ives flow. This tube-fed pahoehoe flow contrasts sharply with other Pinacate lavas in its great volume, alkali-poor composition and morphologic features, which include novel small structures named “spatter tubes.” Despite its K-poor character, young age, and the presence of excess 40Ar, we determined a 40Ar/39Ar age on samples of this flow at 13 ± 3 ka. Such an age determination is made possible via careful monitoring of the mass discrimination of the mass spectrometer and by stacking results from multiple incremental-heating experiments into a single, composite isochron. This age is among the youngest ever to be determined with such precision by the 40Ar/39Ar method on a K-poor tholeiite. |
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| Keywords: | Pinacate volcanic field 40Ar/39Ar dating spatter tubes mass spectrometry |
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