[U-13] Advanced understanding of Quaternary and Anthropocene hydroclimate changes in East Asia:

[U13-P01] Sclerochronology and geochemistry of Mercenaria stimpsoni collected from the western North Pacific

*Kaoru Kubota¹, Kotaro Shirai², Naoko Sugihara², Koji Seike³, Kazushige Tanabe⁴, Masayo Minami⁵, Toshio Nakamura⁵ (1.Graduate School of Human Development and Environment, Kobe University, 2.Atmosphere and Ocean Research Institute, The University of Tokyo, 3.Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology, 4.The University Museum, The University of Tokyo, 5.Institute for Space-Earth Environmental Research, Nagoya University)

Keywords:bivalve, radiocarbon, sclerochronology, oxygen isotope, tsunami, paleoeanography

Bivalve shell is one of the most important archives of past environmental changes because some species can live more than several decades and distribute broadly (e.g., from high to low latitude, fresh/brackish/sea water). We have investigated potential of long-lived cold water bivalve, Mercenaria stimpsoni (Stimpson's hard clam) living in the western North Pacific (especially, coastal area of North East Japan). In this presentation we will show sclerochlonological and geochemical records (e.g., oxygen isotopes and radiocarbon) of both live-caught and dead specimens collected from the seafloor of NE Japan (5–20 m). From both sclerochlonology and nuclear bomb-derived radiocarbon (bomb-¹⁴C), it was found that this animal can live for more than 100 years, thus very useful for paleoeanograpic studies. It was also found that a lot of M. stimpsoni were killed by huge tsunami that hit NE Japan in March 2011, which is likely caused by disturbance of marine sediment, including seabed liquefaction.