西太平洋暖池核心区360ka来上部水体的演变

THE EVOLUTION OF UPPER WATER IN THE CENTER OF WEST PACIFIC WARM POOL DURING THE LAST 360KYR

通过对Ontong Java海台KX97322-4孔浮游有孔虫的定量统计、氧同位素分析以及对各指标的频谱分析,揭示了近360ka来赤道西太平洋暖池核心区浮游有孔虫壳体氧同位素及上部水体垂向结构的冰期-间冰期变化特征。研究表明,MIS10期以来暖池核心区表层种G.ruber和次表层种N.dutertrei的氧同位素都表现出明显的冰期-间冰期旋回,表层水体和次表层水体在大尺度上都总体上受高纬冰盖涨缩影响,次表层水对环境变化更为敏感。上层水体结构变化具有冰期-间冰期旋回特征,温跃层深度在MIS10-MIS8期变深,MIS8-MIS7/8期迅速变浅,MIS7/8以后逐渐变深,进入末次冰期后逐渐变浅趋于稳定波动。频谱分析还表明暖池核心区上层水体性质变化受高纬和热带因素共同作用,与大洋环流也有一定关系。

The Core KX97322-4 was taken from the Ontong Java Plateau,western equatorial Pacific.Quantitative analysis of planktonic foraminifera,combined with oxygen isotope data and spectral analyses of each index,revealed the glacial-interglacial variations of the oxygen isotope of planktonic foraminifera and the vertical structure of the upper water in the center of the West Pacific Warm Pool（WPWP） during the last 360kyr.Our results indicate that,since MIS10,the oxygen isotopes of both the surface dwelling species G.ruber and subsurface dwelling species N.dutertrei’s showed obvious glacial-interglacial cycles.The surface and subsurface waters were influenced by the volume change of high latitude ice sheets in a large scale generally,and the subsurface water is even more sensitive.The variation in upper water structure also imitates the glacial-interglacial cycle.The thermocline（DOT） was getting deeper during MIS10 to MIS8,but abruptly became shallower in MIS8-MIS7/8,then deepened again after MIS7/8 and turned to stable fluctuation when entered the last glacial stage.The spectral analyses indicate that the joint effect of high latitude forcing and tropic-driving caused the variation in the upper water characters.Of course,ocean circulation has also impact on the variation in the upper water structures.