Biogenic silica records in core 17962 from southern South China Sea and their relation to paleoceanographical events
JIA Guo-dong, JIAN Zhi-min, PENG Ping-an, WANG Pin-xian, FU Jia-mo (Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Cuangzhou 510640, China; Marine Geology Department, Tongji University, Shanghai 200092, China)
Biogenic silica is a good proxy for paleoproductivity of sea surface water. A high-resolution accumulation rate record of biogenic silica was obtained from core 17962 taken from the southern South China Sea (7°11'N, 112° 5'E), whose total length and history are 790 cm and ca. 34 000 a, respectively. The record shows that the accumulation rate of biogenic silica in the glaciation were much higher than that in the Holocene. Moreover, the rate in glaciation correlates well with δ~(18)O record in the GRIP ice core and obviously corresponds to the cool events such as Heinrich events and Younger Dryas. Beside, the frequent fluctuations of the rate during Heinrich events reveal that the Dansgaard/Oeschger events may exist in the region. In the southern South China Sea, the strong East Asian winter monsoon could decrease sea surface temperature largely, develop upwelling currents and destroy stratified water body. Consequently, the paleoproductivity raised, which indicated in the record of the accumulation rate of biogenic silica. This result is similar to that in the Chinese loess, where the grain-size maxima, which is indicators of strengthening of the East Asian winter monsoon, corresponded to Heinrich events very well. The transcontinental teleconnection between North Atlantic Ocean and East Asian supports that large scale of paleoclimate process controlled the Heinrich and D/O events.