PALEOENVIRONMENTAL CHANGES IN THE NORTHERN EAST CHINA SEA AND THE YELLOW SEA DURING THE HOLOCENE MARINE TRANSGRESSION

Cores ECSDP-101 (ca. 3m long) and ECSDP-102 (ca. 3m long) and core YMGR-102 (ca. 2m long) were collected from the northern East China Sea, off the mouth of the Yangtze River and from the southern Yellow Sea, respectively. According to AMS 14C ages the northern East China Sea and the southern Yellow Sea began to have been flooded at about 12.3 cal ka BP. In particularly, the d18O and d13C records on the benthic foraminifera Ammonia ketienziensis combined with d13Corg records were used to delineate the paleoceanographic changes from the northern East China Sea to the Yellow Sea during the Holocene marine transgression. The three cores investigated well represent the paleoenvironemtal changes from brackish-estuarine to modern marine conditions associated with rapid global sea level rise during the transition from the Last Glacial Maximum (LGM) the Holocene. In particularly, the establishment of the present marine regimes of the northern East China Sea and the whole Yellow Sea took place at about 6.5 cal ka BP.

However, throughout the Holocene, d18O values of A. ketienziensis from the northern East China Sea are about 1‰ lighter rather than those recorded in the southern Yellow Sea. Furthermore, similar patterns of the d18O values for A. ketienziensis, as recorded in the northern East China Sea and southern Yellow Sea, were also observed in core CC-02 collected from the central Yellow Sea (Kim and Kennett, 1998). In the central Yellow Sea, the d18O values of A. ketienziensis during the Holocene are about 0.3-0.5‰ heavier than those in the southern Yellow Sea. This distinct difference in d18O values of A. ketienziensis probably reflects regional changes in salinity and/or temperature, probably implying the Holocene oceanographic changes from the northern East China Sea to the whole Yellow Sea.