U/PB DATING OF TUFFS FROM THE ALVERSON VOLCANICS IN THE FOSSIL CANYON AND PAINTED GORGE AREAS OF THE COYOTE MOUNTAINS, WESTERN SALTON TROUGH, CALIFORNIA, USA

We report here on U/Pb dating, using LA-ICP-MS, for zircons taken from five locations in the Alverson Volcanics from two areas in the Coyote Mountains. All five locations yielded zircons with ages of 17 Ma. All of the samples are tuffs with three samples stratigraphically above the Alverson flows in the south Fossil-Canyon area, and one sample below and a second sample within the flows in the Painted Gorge area. The samples indicate the all of the Alverson volcanic activity probably occurred at 17 Ma in the Coyote Mountains. The two Alverson-outcrop areas at north Fossil Canyon and Butaca Wash/Lava Gorge were not sampled. Our results compare favorable with previous K/Ar ages from Eberly and Stanley, 1978 [16 ± 1 Ma – Fossil Canyon] and Ruisarrd, 1979 [20.1 ± 1.6 Ma and 21.5 ± 3.9 Ma – north Fossil-Canyon and [14.9 ± 0.5 Ma and 24.8 ± 7.4 Ma – Painted Gorge]. Seven andesite samples taken from flows and domes in the Painted Gorge area have been spectacularly unsuccessful in finding young zircons.