산소동위원소및 알케논에 근거한 동해 심해퇴적물에 대한 후제4기동안의 고수온 복원

Abstract

Paleoenvironmental changes since the last ~ 250 ka was reconstructed based on the oxygen isotope compositions of forminifera and alkenons data from the deep-sea sediments of the piston core (M04-PC1A) taken from the Korea Plateau in the East Sea (Japan Sea). Oxygen isotopic records of the planktonic foraminifera, that were estimated to be ca. 250 ka in age, show the Marine Isotope Stage (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 paleotemperature (about 2 per mil heavier) at the MIS 2.1 and 6.2, respectively. Paleotemperature variations of the surface water in the East Sea were reconstructed using unsaturated longchain alkenones (ULA) along with oxygen isotope data. The result shows that paleotemperature was about 10oC lower than today’s surface temperature during the MIS 6.2. However, paleotemperature during the MIS 2.2 was characterized by relatively small temperature drop of about 5 oC. Both oxygen isotope and ULA data show the systematic coeval trend throughout the late Quarternary.