CHARACTERISTICS OF FORAMINIFERAL ASSEMBLAGES SINCE LAST GLACIAL FROM SHENHU AREA OF NORTHERN SOUTH CHINA SEA AND IMPLICATIONS FOR PALEOCEANOGRAPHIC

The northern slope of South China Sea (SCS), as the area rich in high-resolution depositional records, is critical to the study of regional response and driving mechanism of global change in the South China Sea. For a better understanding of the evolution of the paleoclimate and paleoenvironment since the late last glacial period in SCS, foraminiferal records at Site 6A from the Shenhu hydrate drilling area 2007 on the northern slope are selected as the target to study the foraminifera assemblages with the support of stable isotopes and AMS¹⁴C dating data. Information on sedimentary events since MIS3 of the last 50 000 years has been recorded in the core, and the highest Holocene sedimentation rate is as high as 13.37 cm/ka. In MIS2, there may be lack of deposition due to decomposition of gas hydrate. Benthic foraminifera are present throughout the core. It is easy to distinguish dominant species. The abundance as well as the diversity of the assemblage fluctuates significantly with time. Two stages of high surface productivity in about 40 kaBP and 12~17 kaBP respectively are identified through the analysis of some species with specific ecological significance, such as Uvigerina, Bulimina, Cibicidoidesat, combined with the proportion of porcellaneous shells and variations in planktonic foraminiferal carbon isotopes. The strengthening of summer monsoon in 40 ka was supposed to have brought in a large amount of rainfall, and thus increased the land surface runoff and paleo-productivity. The increase in terrigenous input contributed to the high paleo-productivity 12~17 ka. Furthermore, the North Pacific Deep Water with low temperature, low oxygen content and high nutrient content, may render stronger influence on the core as the winter monsoon enhanced.