赤道西太平洋暖池区更新世以来的生源沉积物沉积特征及其古海洋学意义

DEPOSITIONAL CHARACTERISTICS OF BIOGENIC SEDIMENTS AND THEIR PALEOCEANOGRAPHIC IMPLICATIONS IN THE WEST PACIFIC WARM POOL DURING PLEISTOCENE

赤道西太平洋暖池区中部柱状样 MD972 140中钙质超微化石氧同位素记录和生物地层学的研究为该柱提供了可靠的年龄框架。氧同位素记录与生源和非生源组分的对比表明 ,粗组分和碳酸钙含量变化表现为冰期降低 ,间冰期升高 ,类似于大西洋型旋回 ,而蛋白石和非生源组分却与之相反。更新世以来粗组分和碳酸钙含量的变化总体上是由高到低 ,而蛋白石和非生源组分含量的变化是由低到高 ,反映了陆源物质输入量和表层水生产力的增加。由此可见 ,碳酸钙和蛋白石含量的变化主要受到钙质和硅质生物生产力以及陆源物质输入量的控制。氧同位素 7期以来 。

Deep sea core MD972140 (2°02.58′N,141°45.49′E,water depth 2 547 m,core length 37.41 m) from the central of West Pacific Warm Pool was recovered to study the oxygen isotopic records of calcareous nannofossils and biogenic components and their paleoceanographic implications during the Pleistocene. Oxygen isotopic records and biostratigraphic datum supply a reliable dating control for this core. Correlation of oxygen isotopic records with biogenic and non biogenic components indicates that the abundance of both coarse fraction and calcium carbonate decreased during the glacial periods and increased during the interglacial periods, being similar to “Pacific Carbonate Cycle”. Reversely, both opal and non biogenic components increased during the glacial periods and decreased during the interglacial periods. Abundance changes from high to low in coarse fraction and calcium carbonate and from low to high in opal and non biogenic components during the Pleistocene reflect the increases of terrestrial matter influx and sea surface productivity. Thus, it is inferred that changes of carbonate and opal are controlled by calcium and silicon productivities and terrestrial matter influx. The high abundance in opal and siliceous microfossils during the glacial periods and the lower abundance during the interglacial periods since MIS 7 suggest the fluctuations of surface productivity and siliceous dissolution.