ENVIRONMENT CHANGE FROM POLLEN RECORD IN DEEP SEA CORE FROM NORTHERN SOUTH CHINA SEA
Sun Xiangjun;Li Xun; Luo Yunli(Institute of Botany,Chinese Academy of Sciences, Beijing 100093)(Laboratory of Marine Geology, Tougji University Shanghai 200092)
This paper presents the palynological record of a deep sea core 17940 from the South China Sea (20°07' N, 1 17°23' E, water depth of 1 727 m), and on the basis of Pollen data a vegetation and climate history for the last 37 000 years is reconstructed.During the Last Glaciation (zone P1, ca 37 000~ 15 000aB.P.), the pollen assemblages are dominated by a large amount of herbaceous pollen and those of montane conifer associated with Anthoceros spores, suggesting that the exposed shelf was probably occupied by grassland, with montane conifers growing on nearby mountains. Therefore, the northern part of the South China Sea experienced a remarkable decrease both in temperature and humidity during the Last Glaciation. Strong fluctuations in Percentages with alternating predominance of pollen grains of montane conifer and Artemisia are also observed in the pollen diagram of mis Period, indicating the shifting of the vegetation pattern occurred several bines during that bine. As a result oscillations of relatively cold and moist (dominated by montane conifers) alternatively with temperate and dry climate (dominated by grassland with Artemisia) occurred. During deglaciation from 15 000 - 1 1 300aB. P. (zone P2-a), tropical-subtrOPical broad-leaved taxa increased in pollen assemblages, indicating a rise of temperatUre. The δ 18O curve aso implies a climatic warming occurred during this Period. Therefore it might be comparable with the Blling-Aller d warm stage. From 11 300 - 10 000aB. P., the Percentage of tropical-subtropical broad-leaved taxa are suddenly decreased, due to the re-expansion of taxa of montane conifers and upper montane rainforests, implying a substantial drop of temperatUre but an increase in moistUre. Data from palynology and oxygen isotopes indicate that this event is closely correlated with the Younger Dryas event. DUring Holocene, pollen records are quite similar tO those of surface sediments from the northern South China Sea implying that the vegetation and climate during the last 10 000 years is similar to that at present.
【CateGory Index】： X145
【CateGory Index】： X145