High resolution climate and environmental changes of the northern Japan (East) Sea for the last 40 kyr inferred from sedimentary geochemical and pollen data

Abstract

High-resolution lithological and isotope-geochemical analyses were made on a well age constrained sediment from the northeastern Japan (East) Sea which recorded 10 dark layers (DL) over the last 40kaBP. Pollen analysis of the core allows us to reconstruct the history of surrounding landmass vegetation and to determine pronounced vegetation/climate changes. We found that DL 10 which correlated with a DO/Chinese interstadial 8 was forced by increased East Asian humidity and influx of the nutrient-rich water into the sea. DL 5 formed during the cold Heinrich event 3 (HE), at 30–31kaBP, was most likely to be initiated by the global sea level descent and reduction of seawater exchange with the North Pacific. High resolution of δ18Opf records reflects a unique sensitivity of the Japan (East) Sea to input of the North Pacific water through the shallow Tsushima and Tsugaru Straits. This led us to the important evidence of the eustatic-sea level changes during the last 40kaBP. Since 29kaBP, δ18Opf curve shows a continuous descending sea level interrupted by sharp drops of HE 2 with a following rise of DO interstadial 2. A sharp δ18Opf increase since 18.6kaBP is consistent with coral results which indicate abrupt termination of LGM low stand by a rapid sea level rise initiated at 19.0kaBP.