과거 약 40만 동안 동해의 SST 변화: 고기후, 고해양 변화의 함의

Abstract

SST (Sea Surface Temperature) variations were reconstructed on the basis of oxygen isotope compositions of foraminifera and alkenons data from the deep-sea sediments piston core (M04-PC1A) taken from the Korea Plateau in the East Sea since the last Marine Isotope Stage (MIS) 8. Oxygen isotopic records of the planktonic foraminifera, that were estimated to be ca. 320 ka in age, show the MIS from 1 to 8. Comparing this result with previously reported stable isotope data in the East Sea as well as the global oxygen isotope trend, it is suggested that paleoceanographic and paleoclimatic changes in the East Sea has been quite different from those of open oceans: it reserves freshwater input signals and steep drop of SST (about 2 per mil heavier) at the MIS 2 and 6, respectively. Especially, SST variations of the surface water in the East Sea were reconstructed using unsaturated long chain alkenones (ULA) along with oxygen isotope data. The result shows that SST was about 10oC lower than today’s surface temperature during the MIS 6. However, SST during the MIS 2 was characterized by relatively small temperature drop of about 3 oC. Both oxygen isotope and ULA data show the systematic coeval trend throughout the late Quaternary. The relatively big SST differences between MIS 6 and MIS 2 may closely relate with paleoceanographic environmental changes such as deep water circulation, local river