Vegetation evolution and its response to climatic change during 3.15-0.67 Ma in deep-sea pollen record from northern South China Sea

In order to study vegetation evolution and environmental change during 3.15-0.67 Ma,a total of 608 pollen samples with an average time resolution of 4 ka has been analyzed from ODP Site 1145(water depth 3175 m),northern South China Sea.The deep-sea sediments(213.62-91.9 m) cover from 3.15 to 0.67 Ma based on micropaleonotological stratigraphy.The characteristic features of the pollen diagram include that,pollen influx rises twice obviously around 2.58 Ma and during 2.0-1.8 Ma,in response to global climatic cooling and winter monsoon enhancement.Before 2.58 Ma,tropical and subtropical vegetation,mainly evergreen Quercus(E) and Altingia,predominated around northern SCS with much more tropical montane conifers and ferns relatively.From 2.58 Ma,temperate vegetation increased obviously,implying climatic cooling and winter monsoon enhancement.Spectral analysis shows that percentage variation in tropical and subtropical taxa has a strong 20 ka procession cycle probably due to the summer monsoon;while pollen influx has 100,41 and 19 ka cycles,indicating the sea level and winter monsoon change response to the ice-sheet variations.

In order to study vegetation evolution and environmental change during 3.15~）.67 Ma, a total of 608 pollen samples with an average time resolution of 4 ka has been analyzed from ODP Site 1145 （water depth 3175 m）, northern South China Sea. The deep-sea sediments （213.62-91.9 m） cover from 3.15 to 0.67 Ma based on micropaleonotological stratigraphy. The characteristic features of the pollen diagram include that, pollen influx rises twice obviously around 2.58 Ma and during 2.0-1.8 Ma, in response to global climatic cooling and winter monsoon enhancement. Before 2.58 Ma, tropical and subtropical vegetation, mainly evergreen Quercus （E） and Ahingia, predominated around northern SCS with much more tropical montane conifers and ferns relatively. From 2.58 Ma, temperate vegetation increased obviously, implying climatic cooling and winter monsoon enhancement. Spectral analysis shows that percentage variation in tropical and subtropical taxa has a strong 20 ka procession cycle probably due to the summer monsoon; while pollen influx has 100, 41 and 19 ka cycles, indicating the sea level and winter monsoon change response to the ice-sheet variations.