The paleoclimatic change since the last glaciation in the north of Okinawa Trough based on the spore-pollen records

On the basis of spore-pollen assemblage analysis in the piston core CSH.collected in the northern Okinawa Trough,the history of vegetation and climatic variation on islands nearby the Okinawa Trough during the Last Glaciation was reconstructed.The shape of spore-pollen curves makes it possible to subdivide the succession into different time inter vals.PeriodⅠis the prosperous period of torpic serra coniferous forest,when pinus and semitropical alpine aiphyllus coniferous forest flourished.The derived spore-pollen assem blage suggests that the paleoclimate during that period is arid and warm.PeriodⅡis a prosperous period of xerolphitic herbage,when Artemisia plants prosper,which suggests the climate is xeric and large-scale marine regression may have occurred.Period Ⅲ is the prosperous period for everg reen latifoliate forest,the decilious broadleaved forest increases,the relative abundance of ferns spore reaches the maximum while herbs decreases rapidly,which suggests it is warm and humid.Atotal of six cooling events were identified based on the curves of some especial pollens,these cold events occurred at 4.1~4.6,11.7~13.0,15.4,23.2,29.4 and 47.4 ka BP respectively and showed good correlation with the coldest stadials of Dansgaard-Oeschgercy cles documented in the record of δ¹⁸O from the Greenland GRIP ice core,which correspond to the Younger Dry as event and the four Heinrich events H1,H2,H3 and H5.