EVIDENCE FOR TEMPORAL FLUCTUATIONS IN MARINE RADIOCARBON RESERVOIR AGES IN THE SANTA-BARBARA CHANNEL, SOUTHERN CALIFORNIA

Differences in the C-14 ages of closely associated marine shell and ca rbonized plant material from stratified archaeological deposits on San Miguel Island, California, suggest Holocene (10,000-present) fluctuat ions in marine C-14 reservoir ages. These fluctuations coincide with d elta(18)O and delta(13)C shifts measured in Mytilus californianus shel ls from the same stratigraphic contexts and general atmospheric/oceani c circulation models for the region. Based on these data we make three primary observations: (1) significant changes appear to have occurred in the radiocarbon reservoir during the Holocene; (2) these fluctuati ons appear to correlate with regional oceanographic changes; and (3) h igh resolution C-14 dating of marine shells may require different Delt a R values for different periods of time. (C) 1997 Academic Press Limi ted.