Radiocarbon reservoir ages in the Holocene sediments off the Sanriku coast, Northeast Japan

Abstract

To investigate the relationship between paleoenvironmental changes and marine reservoir effects, the radiocarbon ages of marine shells and terrestrial plants from the same horizons of sediment cores in the Holocene Epoch were compared. Three sediment cores were obtained from the central to northern parts of the Sanriku coast, corresponding to the boundary between the warm Kuroshio and cold Oyashio currents. These drilling sites are also located in a tectonically active area associated with the subduction of the Pacific Plate in Japan Trench. Based on lithological analysis, molluscan assemblage investigation, and radiocarbon dating, we interpreted five sedimentary facies. These paleoenvironmental changes were mainly related to sea level rise during the last deglaciation period. Reservoir ages from 33 pairs of terrestrial plants and marine shells (420 ± 130 14C years) were found to span the period from 2,300 to 9,000 cal BP.