2本のピストン・コアの有機炭素量に基づく日本海の古環境変化

抄録

Organic carbon contents of two piston cores from the southern part of the Japan Sea are closely related with the lithology and relative abundance of a benthic foraminiferal species, Bolivina pacifica. That is, the organic carbon content is high in the layers of homogeneous clay, intensive burrowed clay, and thin-laminated clay with abundant occurrence of Bolivina pacifica, but low in the layers of weak burrowed clay and thin-laminated clay without benthic foraminifera. The sequential changes of the organic carbon content for the two cores are similar to the general pattern of the oxygen isotopic curve in the open ocean. This suggests that the paleoceanographic change of the Japan Sea has been essentially controlled by the global climatic changes, which link with eustatic sea level fluctuations. The detailed paleoenvironmental change in the Japan Sea since the oxygen isotopic stage 5₁ (8.5ky B.P.) is reconstructed on the basis of the organic carbon content as well as the lithological and benthic foraminiferal faunal changes in the cores.