Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA; Department of Earth Science, University of California, Santa Barbara, CA 93106, USA
Department of Earth Science, University of California, Santa Barbara, CA 93106, USA
Department of Earth Science, University of California, Santa Barbara, CA 93106, USA
Department of Geology, Occidental College, Los Angeles, CA 90041, USA