晚更新世南海不同海区的浮游有孔虫群落特征差异及环境控制因素

DISCREPANCY IN THE PLANKTONIC FORAMINIFERAL ASSEMBLAGES FROM THE NORTHERN, SOUTHERN AND WESTERN SOUTH CHINA SEA SINCE MIS12 AND ITS IMPLICATION IN MARINE PALEOENVIRONMENTAL STUDY

本研究对晚更新世以来(~45万)南海西部浮游有孔虫进行定量统计分析,并与南海北部和南部该时期的浮游有孔虫组合进行比较。研究发现,南海浮游有孔虫组合在以Globigerinoides ruber和Globigerinoides sacculifer为代表的热带-亚热带组合面貌为特征的背景下,其不同海区的浮游有孔虫组合具有显著差别。在南海北部,浮游有孔虫冷水型分子丰富,具有较高含量的Globorotalia inflata,Globigerina bulloides和Neogloboquadrina dutertrei等;南海西部的暖水种、冷水种含量均居中,以Globigerinita glutinata和Neogloboquadrina pachyderma高含量为特征;而南海南部则完全以具有高含量的G.ruber,G.sacculifer和Globorotalia menardii等暖水种为特征。在冰期-间冰期旋回变化中,南海北部浮游有孔虫群落面貌变化较大,南部则相对变化较小、西部变化最小。在间冰期,南海西部N.dutertrei,G.inflata,G.bulloides,G.glutinata和N.pachyderma等属种含量升高,有孔虫群落显示出上升流区特色。南海不同海区有孔虫特征属种及组合的差异,反映出有孔虫对海洋环境差异响应的敏感性,同时对海区古海洋环境研究具有参考意义。

Planktonic foraminiferal analysis was quantitatively performed at Site MD05-2901 in this study, and compared with data from Site 1146(in the northern South China Sea)and Site 17957(in the Southern South China Sea) since MIS 12 to reveal the effect of regional ocean environment on the planktonic foraminifers in the South China Sea(SCS). Apparent difference in glacial-interglacial foraminiferal assemblages were found at Site 1146. The abundances of temperate water species were high and the warm water species were low in Site 1146, with the characteristic higher composition of G. inflata, G. bulliodes and N. dutertrei, which implies a strong winter monsoon influenced in the northern SCS. At Site 17957, foraminiferal assemblage is dominated by G. ruber, G. sacculifer and G. menardii, showing high contents of warm water species and low contents of temperate water species. In addition, the foramini-feral composition varies less during the glacial-interglacial cycles, which implies that the southern SCS environment is influenced by the western Pacific Warm Pool. The foraminiferal fauna of Site MD05-2901 show transition characteristics, the contents of warm water species and temperate water species are in the middle, with highest contents of G. glutinata and N. pachyderma, but the faunas show little difference during the glacial-interglacial cycles, which displays the foraminiferal character of the upwelling area in the western SCS. The foraminiferal faunal comparisons between different parts of the SCS show the obvious climatic zonation, and monsoon influences on the planktonic foraminifers was suggested during the Late Pleistocene.