Evolutionary Paleoceanographic Characteristics in the Northern South China Sea Since Late Pleistocene: Evidence from Core N31
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摘要: 对南海北部N31柱状样沉积物进行了浮游有孔虫定量分析鉴定、氧碳同位素、碳酸盐含量和粒度测试以及AMS14C测年，并采用古生态转换函数计算了表层海水古温度和温跃层深度，揭示了该海区约55 ka以来的古海洋环境特征。转换函数计算的表层海水古温度结果表明，夏季温度的变化范围为27.0~29.6℃，变化幅度为2.6℃，冬季温度变化范围为18.2~27.0℃，变化幅度为8.8℃。与南海南部转换函数温度对比表明，南海南部的温度比南海北部要高，这种差异在冬季时表现更为突出。温跃层转换函数计算的温跃层深度结果表明，MIS3~MIS2期时温跃层深度没有大的变化，而从冰期向冰后期过渡时，温跃层深度逐渐增大。
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关键词:
- 古海洋环境浮游有孔虫晚更新世南海
Abstract: The South China Sea is the largest marginal sea in the western Pacific Ocean and its' north and south are wide continental shelf. There are many rivers flow into the South China Sea. The highresolution sediment records abundant environmental information of land and sea. This area has become one of hotspots on paleoceanography research and made a lot of research results. Planktonic foraminifera are very sensitive to changes of marine environment. Sea water temperature changes can directly affect the migration and succession of biota. Therefore, research the distribution of planktonic foraminifera in core sediment to analyze the evolution of paleoclimate. In this paper, a sediment Core N31 located in the northern South China Sea had been researched including quantitative analysis and identification of planktonic foraminifera, oxygen and carbon isotopes, carbonate content and grain size, AMS14C dating, sea surface temperature and thermocline depth calculated by paleoecological transfer function. The following conclusions have been attained:
1) The bottom age of Core N31 was about 55ka BP and this core accepted deposition since marine isotope stage 3.
2) Planktonic foraminifera species analysis showed that changes in abundance as the glacialinterglacial cycles and change. Tropical and subtropical species appeared in lager numbers in interglacial and its maximum percentage in MIS3 or MIS1, but temperate species appeared in larger numbers in the glacial period.
3) The sea surface temperature (SST) estimated by the transfer function FP12E shows that the summer SST ranges from 27.0 to 29.6℃ and the winter SST from 18.2 to 27.0℃. The comparison of SST data between the southern and northern SCS shows that SST in the southern SCS is higher than that in the northern SCS. The SST difference is more obvious in winter.
4) The thermocline data show no obvious fluctuations during MIS3MIS2, but the depth deepened gradually during the transitional period from the glacial to the postglacial.
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Key words:
- paleoceanography
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