Paleoceanographic envronmental evolution in the East Sea (Japan Sea)

Abstract

Geochemical proxies of stable oxygen isotope of foraminifera, carbon and nitrogen isotope of organic matter, and total organic carbon (TOC) and inorganic carbonate content of two piston cores taken from the Korea Plateau, East Sea (Japan Sea) were investigated to understand the paleoceanographic and evolution since the last 400 kyr. Oxygen isotope signals of foraminifera shows large fluctuation, ranging from MIS (Marine Isotope Stage) 1 to MIS 11 with a distinctive glacial-interglacial variation. Comparison of oxygen isotopic record for glacial and interglacial conditions during the 400 kyr reveals that paleoceanographic and paleoclimatic changes in the East Sea is quite different from those of open oceans. The content of biogenic carbonate, TOC and carbon and nitrogen isotope of organic matter (δ13C and δ15N) were determined and used to interpret paleoenvironmental changes during glacial and interglacial periods. Based on the isotopic composition of δ13C and δ15N, which showed extreme temporal variation since MIS 11 influx of large amount of terrestrial organic matters from the neighboring continent during MIS 2, 8 and 10 can be implied. In particular, depleted values of δ13C during MIS 2, 8 and 10 were coincident with lower nitrogen isotope values indicating local paleoceanographic effects such as paleoproductivity changes. Therefore, the paleoenvironment in the East Sea is sensitivn Sea) were investigated to understand the paleoceanographic and evolution since the last 400 kyr. Oxygen isotope signals of foraminifera shows large fluctuation, ranging from MIS (Marine Isotope Stage) 1 to MIS 11 with a distinctive glacial-interglacial variation. Comparison of oxygen isotopic record for glacial and interglacial conditions during the 400 kyr reveals that paleoceanographic and paleoclimatic changes in the East Sea is quite different from those of open oceans. The content of biogenic carbonate, TOC and carbon and nitrogen isot