南海南部沉积物中黏土矿物组成变化及其古沉积信息记录初探

通过对南海南部2个代表13万a以来柱状沉积样品高分辨率的黏土矿物组成分析,认为所研究的黏土矿物主要为陆源碎屑成因,埋藏过程中的成岩变化或黏土矿物自生特征不明显,而以采样点南面加里曼丹岛、菲律宾东、西两侧的火山群岛和湄公河流域为主要陆源的地质条件、风化环境及物质迁移途径的差异控制了南海南部沉积物中黏土矿物组成的空间和时间变化.研究发现,沉积物样品中较高的蒙皂石含量对应于地质历史上的暖期,而较低的蒙皂石含量对应于冷期.伊利石的行为及其古海洋指示意义则与蒙皂石相反.将柱状沉积物样品上高分辨率的黏土矿物组成分析作为一种研究方法,有助于研究晚第四纪以来南海陆源碎屑物的源区特征、迁移途径及海区古环境演变.

On the variation of clay minerals and their paleosedimentary records in the sediment cores in the southern area of the South China Sea

Based on XRD results of clay mineral components with high resolution sampled sediments from two gravity cores with a sedimentary history about 130 000 a in the southern part of South China Sea, it is recognized that the clay minerals are mainly of terrigenous rather than authigenic origin. The differences in geologic condition, weathering environment and transport route in the lands around the study area, such as Kalimantan Island in the east, control the spatio-temporal variation of component distribution of clay minerals along the sedimentary core. It is interesting to discover that high concentration of smectite corresponds to the warm or interglacial period, and low concentration of smectite to the cold or glacial period. The behavior and paleoceanographic indication of illite are opposite to those of smectite. As a research method, the high-resolution study of clay components in the sediment cores will be helpful to explaining the source characteristics, transport path and paleoclimatic evolution since the late Quaternary in the South China Sea.