MILLENNIAL SCALE PALEOCEANOGRAPHIC VARIATIONS FROM THE LAST GLACIAL IN THE SOUTHERN SOUTH CHINA SEA

Quantitative analyses of planktonic foraminifera and coccoliths were carried out on the sediments from core MD05-2896 in the southern South China Sea. Abundance variations of index species of planktonic foraminifera and Florisphaera profunda, and the technique of FP-10E and SIMMAX-28 were used to reconstruct paleoceanographic changes in the sea surface temperature, upper ocean water structure, primary productivity and carbonate dissolution and their periodicity in the southern South China Sea over the last 22.8 ka. The result shows. (1) during the earlier period from 22.8 to 18 ka and later period since 10 ka, the sea surface temperature increased, carbonate dissolution reinforced, the depth of thermocline and nutricline deepened and the primary productivity was relatively lower; (2) from 18 to 10 ka, the sea surface temperature was lowest, carbonate dissolution weakened, the depth of thermocline and nutricline shoaled and primary productivity was highest; and (3) during the last 10 ka, the sea surface temperature increased, the depth of thermocline and nutricline deepened and the primary productivity reduced, and car-bonate dissolution increased after 7 ka. The spectrum frequency analysis result demonstrated that the climate change had obvious cyclicity fluctuation over past 22.8 ka. The dominant period is 1 500 years, which is similar to millennial D/O event. Besides,the climate change also has some small periods such as the periods of 700-900 years and 500 years.