Molecular biomarker record of paleooceanographic environment in the East China Sea during the last 35000 years

By reference of the δ18O and δ13C isotopic compositions of G.sacculifer and accelerator mass spectrometry (AMS)14C dates, the UK37, ∑C–21/∑C+-22 and Pr/Pn in core DGKS9603 have been used to characterize the changes of paleooceanographic environment occurring in the East China Sea (ECS) during the last 35000 years. The stratigraphic records of these proxies have shown that during the last 35 ka the Okinawa Trough has gone through 7 stronger cold-climate events (C1–C7) and 9 terrigenous matter-decreasing events (e2–e9), of which, the C1 corresponds to the cold episode occurring in the middle late Holocene, C2–C4 and C7 correspond to the H1–H4 events, respectively. e1 and e3–e8 correspond to the decrease of sea surface temperature (SST), respectively. The terrigenous inputs increased when Heinrich events occurred. Climate colding resulted in the decrease of terrigenous matter transported by rivers, and the increase of that transported by winter monsoon. Heinrich events are closely related to East Asia monsoon. During the Last Glacial Maximum (LGM, 15.5–25.8 Cal ka BP), reduction environment fluctuated strongly, bringing forth three stronger reduction events (R1–R3) and one weaker reduction event (O), of which, R1–R3 correspond to the decrease of SST and increase of terrigenous nutrient and O corresponds to the decrease of terrigenous nutrient. The fluctuation of reduction condition must be related to the change of sea surface productivity.