ENVIRONMENTAL CHANGES SINCE MID HOLOCENE REVEALED BY CORE Z1 IN THE SOUTH YELLOW SEA AND THEIR RESPONSE TO EAST ASIAN MONSOON

High-resolution multi-proxies records, including AMS ¹⁴C ages, grain size and TOC/TN for a gravity core Z1 from the South Yellow Sea were collected in this program. The variation in grain size is closely related to the resuspension and coastal currents droved by the East Asian Winter Monsoon(EAWM). And the organic geochemistry proxy TOC/TN could be used to indicate the input of terrigenous materials and/or the intensity of ocean primary productivity.Our results reveal the evolution history of the sedimentary environment in the area of muddy deposits in the South Yellow Sea since Mid Holocene, which could be divided into three stages:(1)A relatively high-energy and stable sedimentary environment with low ocean productivity from 6.1 to 5.4 ka BP corresponding to the strong and stable EAWM; (2)A weakening and variable hydrodynamic condition at 5.4~3.9 ka BP associated with fluctuating and weakening EAWM; (3)A low-energy and stable sedimentary environment with high ocean productivity since 3.9 ka BP related to the weakened and stable EAWM. Correlation between regional records and global climate variations reveals that, the grain size was coarser at 6.0 ka BP, 5.3 ka BP, 4.6 ka BP, 4.0 ka BP and 3.4 ka BP corresponding well in time to the strengthening of EAWM. However, The high deposition rate during 6.1~5.7 ka BP is related to the EAWM and during 2.8~1.9 ka BP, owing to the strengthening of YSWC, the stabilization of cyclone cold water mass of Yellow Sea might increase the depositional process.