RESPONSE OF COCCOLITH RECORDS IN THE SOUTH CHINA SEA TO CARBON ISOTOPE MINIMUM EVENTS

The occurrence of carbon isotope minimum events at deglaciations is a common feature of marine carbon isotopic records in late Quaternary. Coccolith analysis has been carried out for 930 sediment samples of the core MD05-2904(19°27.32'N, 116°15.15'E,water depth 2 066 m,core length 4 498 cm)from the northern South China Sea. The results revealed that the relative percentage variations of the predominant coccolith taxa (Florisphaera profunda,Gephyrocapsa oceanica and Emiliania huxleyi) were correlated to the carbon isotope record of planktonic foraminifera. While the δ¹³C became heavier since MIS5, the percentage of G. oceanica increased and lower euphotic species F. profunda decreased, indicating the rise of primary productivity. Corresponding to the three δ¹³C minimum events, significant changes occurred in the coccolith assemblages and marine primary productivity peaks appeared in deglaciations. It reflects that carbon isotope minimum events may be closely related to the variations of phytoplankton community and paleoenvironmental change. The present results demonstrate that coccolith records can provide evidence for the research of ocean carbon reservoir.