Geological and Environmental Sciences, Stanford University, Stanford, CA 94720-4740 United States
Center for Accelerator Mass Spectrometry, LLNL, Livermore, CA 94551 United States ; Department of Ocean Sciences and Institute of Marine Sciences, University of California, Santa Cruz, Santa Cruz, CA 95064 United States
Center for Accelerator Mass Spectrometry, LLNL, Livermore, CA 94551 United States
Geological and Environmental Sciences, Stanford University, Stanford, CA 94720-4740 United States
Research School of Earth Sciences, Australian National University, Canberra, ACT 0200 Australia