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采用沉积地球化学、沉积物矿物成分分析等手段研究发现,自渐新世以来,南海北部沉积物成分具有阶段性改变的特征。在早渐新世,沉积物反映出其母岩以花岗岩和区域变质岩为主;到晚渐新世,母岩中区域变质岩类型消失,而以花岗岩、沉积岩和接触变质岩为特征;进入中新世,沉积物主要反映出碳酸盐岩等沉积岩为主的源区特点。这种沉积物成分演变特征与南海北部盆地基底及珠江流域不同区域物质组成特征极为一致,反映出珠江流域演化与南海北部沉积充填之间的对应关系。因此,通过这种研究方法,可以更好地理解32Ma以来南海北部沉积物成分发生改变的原因。同时,可以通过对比南海北部古珠江来源沉积物各时期的成分特点,建立珠江流域的侵蚀-搬运-沉积过程,探讨珠江流域演化历史。
Using sedimentary geochemistry and analysis of mineral composition of sediments, it has been found that the sediment composition in the northern South China Sea has a stage-changing characteristic since the Oligocene. In the Early Oligocene, the sediments reflect that their parent rocks are dominated by granites and regional metamorphic rocks. By the Late Oligocene, the metamorphic rocks in the parent rocks disappear but are characterized by granite, sedimentary rocks and contact metamorphic rocks. In the Miocene, the sediments mainly reflect the characteristics of the source areas mainly composed of sedimentary rocks such as carbonate rocks. The evolution of sediment composition is consistent with the characteristics of the material composition in different basins of the basin and the Pearl River basin in the northern South China Sea. It reflects the corresponding relationship between the evolution of the Pearl River Basin and the sedimentary filling in the northern South China Sea. Therefore, by this method of study, the reason for the change of sediment composition in the northern South China Sea since 32 Ma can be better understood. At the same time, we can establish the process of erosion-transport-sedimentation in the Pearl River Basin by comparing the characteristics of the sediments of the ancient Zhujiang River source in the northern South China Sea and discuss the evolution history of the Pearl River Basin.