南海东北部184柱状样沉积中生源和矿物碎屑组分分析及其古环境意义

COMPONENT ANALYSIS OF THE BIOGENIC AND MINERAL CLASTICS IN CORE 184 OF THE NORTHEASTERN SOUTH CHINA SEA AND ITS PALEOENVIRONMENTAL SIGNIFICANCE

通过对南海东北部184柱状样的29个沉积样品的定量研究,揭示了生源和矿物碎屑各组分在柱状样中的垂向分布,显示了在海洋古环境研究中组分分析作为一种简单、快速的研究方法的潜力。研究区生源碎屑的分布明显受与水深相关的深海溶解作用所控制,水深3 500~4 000 m的现代南海CCD以下,钙质生物的含量急剧减少,而硅质生物的含量急剧增加。火山玻璃在柱状样的分布位置与氧同位素分期的对比,显示出其可以成为地层对比和确定年龄的良好标志。

The compositions of biogenic and mineral clastics from core 184 (16°99.5′N,117°54.17′E, water depth 3 947 m), which was taken from the northeastern South China Sea (SCS) and near the carbonate lysocline and compensation depth (CCD) of the modern SCS, have been quantitatively examined. It has been demonstrated that the component analysis is potential to be a simple and fast method in the marine paleoenvironmental study. The stratigraphy of this core was mainly based on the comparison of volcanic glass and carbonate contents with those of nearby cores that had planktonic foraminiferal (δ^(18)O) records. The variation in relative abundance of biogenic clastics is obviously controlled by the deep-sea dissolution related to water depth and climate change. Calcareous biogenic clastics remarkably increase in abundance while siliceous biogenic clastics decrease during the last glacial stage, and it was the opposite during the interglacial stage. The mineral clastics in core 184 mainly come from the Asian continent, with the Luzon Island as a secondary source of weathering materials. The distributions of these mineral clastics are controlled by the transportation related with the distance to shore and also the direction of surface currents.