末次冰期热带西太平洋硅藻席沉积中硅藻记录对古环境的响应

PALEOENVIRONMENTAL CHANGES DURING LAST GLACIAL STAGE INFERRED FROM DIATOM RECORDS OF THE DIATOM MAT DEPOSITS FROM TROPICAL PACIFIC

通过对末次冰期热带西太平洋硅藻席沉积区WPD-03孔的硅藻鉴定结果进行主成分分析,得出主成分Ⅰ可表示该孔海表盐度的变化,且得分越高,表示盐度越低;主成分Ⅱ可表示该孔海表温度的变化,且得分越高,温度越高。在过渡层段也即MIS3期的晚期,由于盐度相对较低的海水上涌,使海表盐度降低的同时带来大量营养物质,导致非成席硅藻的勃发。继而"低盐帽"的形成促使海水的成层化,诱使成席硅藻勃发,导致"秋季沉降",从而形成硅藻席沉积。亦说明盐度相对较低海水的输入,可能是研究区硅藻席沉积形成的诱因之一。

The diatom mat deposits indicate the blooming and quick deposition of diatoms. They are well developed in the western tropical Pacific during the last glacial stage. The Principal Component Analysis （PCA） of the diatom from the core WPD-03 indicate that the principal component I （PC I） can represent changes in sea surface salinity（SSS）, the higher the score, the lower the salinity; whereas the principal component II （PC II ） may indicate sea surface temperature （SST） changes, the higher the score, the higher the temperature. In the late period of MIS3, because of the upwelling of low salinity water, the sea surface salinity was decreased as the nutrients increased. It resulted in the blooming of non mat-forming di- atoms. The ＂low salt cap＂ will cause the initiation of stratification, and induce giant diatom blooming, which resulted in ＂Fall dump＂, thus formed the mat diatom deposits. It may also indicate the input of low salinity seawater into the study area, as one of the reasons for the formation of the diatom mat deposits.