南海深海沉积物花粉记录的快速气候波动事件

本文根据１７９４０柱状样花粉研究结果,分析了南海末次冰期以来千年尺度气候波动事件,并利用频谱分析方法得到南海深海沉积物花粉记录的气候变化的周期。本文研究认为,这种千年级准周期的气候波动可能与高纬度地区的亚米兰科维奇准周期性事件进行对比；它也可能反映了Ｅ１Ｎｉｎｏ－ＳｏｕｔｈｅｒｎＯｓｃｉｌｌａｔｉｏｎ(ＥＮＳＯ)系统较长周期的变化,其形成和演化机制仍待进一步探讨。

MILLENNIAL-SCALE CLIMATIC FLUCTUATIONS IN POLLEN RECORD OF DEEP SEA DEPOSIT FROM SOUTH CHINA SEA

The high resolution palynological analysis of a deep sea Core 17940 from SouthChina Sea（20°07＇N, 117°23＇ E, water depth of 1 727m） shows that the pollenassemblages are dominated by Pinus, montane conifers （Picea, Abies and Tsuga） andherbaceous pollen （Artemisia） and characterized by strong fluctuations in percentagesof montane conifers and Artemisia pollen indicating abrupt changes of the vegetationand climate during the last glaciation （calendar year 40 000～18 000a B. P.）. Thepollen assemblage predominated by Artemisa reflects a compalatively dry andtemperate climate, whereas those characterized by montane conifers implies relativelycold and humid climate. Based on the frequency spectrum analysis, some 6 750a,2 900a and 2 100a cyclicities are obtained in variation of Artemisia and montaneconifers pollen percentage. The 6 750 a cyclicity could be correlated with the Heinrichcold events recorded from the North Atlantic deep-sea deposits; while the 2900a and2 100a cyclicities might be corelated with the Dansgaard/Oeschrge warm events （D/Oevents） recorded from the GRIP ice core.In the western Pacific E1 Nino is linked and phase-locked with the seasonalmonsoon circulation system. Although the mechanism of long-term ENSO variabilityremains nuclear, some millennial cycles （such as 2 500a cycle, 2 000a cycle and 1 000～3000a cycle） have been found to be linked to ENSO system in recent studies ^10～12].The South China Sea is influenced strongly by the East Asian monsoon and theENSO system, hence the vegetation and climate changes recorded by pollen data fromthe Core 17940 might be a quasi-cyclicity related to millennial-scale fluctuations inthe ENSO system in the tropical Pacific. Additional work is required to reveal therelationship of the recorded climate change to the ENSO system.