40 Ar/ 39 Ar Age of the Lathrop Wells Volcanic Center, Yucca Mountain, Nevada

Abstract

Paleomagnetic and ⁴⁰Ar/³⁹Ar analyses from the Lathrop Wells volcanic center, Nevada, indicate that two eruptive events have occurred there. The ages (136 ± 8 and 141 ± 9 thousand years ago) for these two events are analytically indistinguishable. The small angular difference (4.7°) between the paleomagnetic directions from these two events suggests they differ in age by only about 100 years. These ages are consistent with the chronology of the surficial geological units in the Yucca Mountain area. These results contradict earlier interpretations of the cinder-cone geomorphology and soil-profile data that suggest that at least five temporally discrete eruptive events occurred at Lathrop Wells approximately 20,000 years ago.