PALEOCEANOGRAPHIC AND PALEOCLIMATIC RECORDS FROM DSDP SITE 188 IN THE BERING SEA SINCE MARINE ISOTOPIC STAGE 3

Quantitative analytic results of the biogenic components at DSDP Site 188 on the west edge of Bowers Ridge in the southern Bering Sea indicate that the opal content, serving as proxies of surface productivity, increased during the early and late MIS 3 and late MIS 2, reflecting the enhancement in surface productivity. However, the surface productivity deceased at other intervals and its change did not respond to the glacial-interglacial cycles. C/N ratio in sediments, indicating the mixed source, reflects the possible influence of terrigenous organic matter input on the surface productivity. The results of non-biogenic components at DSDP Site 188 show that the terrigenous detritus input increased during early and late MIS 3 and MIS 2, displaying the evident fluctuation of current and climate. The charcoal detritus increased during MIS 3 and the last deglaciation and decreased during the MIS 2, suggesting probability of natural fires higher during interglacial periods than during glacial periods, which linked with the climate over the North American Continent and responded to global climate change during late Quaternary glacial and interglacial cycles.