[M-IS01_29PM2] Land-ocean linkages in East Asian marginal seas

[MIS01-08] Shallow water environmental change in the Sea of Japan during the last 30 kyr deduced from foraminiferal isotopes

*佐川 拓也¹、内田 昌男²、村山 雅史³、多田 隆治⁴ (1.九州大学大学院理学研究院地球惑星科学部門、2.国立環境研究所、3.高知大学海洋コア総合研究センター、4.東京大学大学院理学系研究科地球惑星科学専攻)

キーワード：Sea of Japan, oxygen isotope, planktonic foraminifer

The Sea of Japan is a marginal sea that connects with North Pacific and adjacent marginal seas by four shallow straits. Because water depth of the deepest straits today is ~130 m (Tsushima Strait and Tsugaru Strait), environments of Sea of Japan have been strongly affected by sea level fluctuations related to the glacial-interglacial cycles. Previous studies report that foraminiferal oxygen isotope variation from Sea of Japan is distinct from that commonly seen in seas of the world. Since Sea of Japan is nearly isolated from adjacent seas during the glacial maxima, salinity of surface water significantly decreases, and therefore foraminiferal isotopes show the lowest values due to the unique fresh water balance. The peak value of oxygen isotope is ~0.5 per mil at the last glacial maximum, which is ~2.5 per mil lighter than at 30 ka. We review literature data and present new results of two sediment cores from northeastern and southern part of Sea of Japan. The new data from southern core has ~70-yr resolution and shows abrupt shift that may correspond to abrupt climate change reported from the Greenland ice core and Asian monsoon proxy data of Chinese Cave and Loess. The new results suggest that the surface environment of Sea of Japan is sensitive to eustatic sea level change as well as abrupt climate changes.