南海北部陆坡DLW3101孔MIS5期以来的古海洋学信息

Paleoceanographic Information of the Core DLW3101 in the Northern Slope of the South China Sea Since MIS5

对取自南海北部白云凹陷陆坡峡谷顶部的DLW3101孔进行了氧同位素、CaCO3质量分数、平均粒径(Mz)及磁化率(κ)测试,建立了该孔MIS5期以来的地层年代框架,利用CaCO3和磁化率参数重建了MIS5期以来南海北部的古气候波动历史。DLW3101孔具有典型的“大西洋型”CaCO3旋回特征,CaCO3质量分数主要受华南陆源碎屑的稀释作用控制。磁化率与CaCO3质量分数呈负相关性,其值受沉积物中CaCO3稀释作用的影响。末次间冰期(MIS5期)海平面高,钻孔处陆源输入物以少量细粒物为主,CaCO3因陆源物质稀释使用较弱而含量较高,磁化率因CaCO3的稀释较强而较小;末次冰期(MIS2-MIS4期)海平面降低,钻孔处陆源输入物以大量粗颗粒物为主,CaCO3因陆源物质稀释作用强而含量低,磁化率因CaCO3的稀释减弱而较高。冰后期(MIS1期)海平面逐步升高,DLW3101孔离陆距离越来越远,沉积物中的CaCO3质量分数因陆源物质的稀释作用逐步降低而逐步增高。

In this study, the oxygen isotope, calcium carbonate content and magnetic susceptibility of the Core DLW3101 collected from the top site of the canyon area on the northern slope of the South China Sea (SCS) were measured. Based on the measured data, we established the stratigraphic age framework and reconstructed the history (since MIS5) of paleoclimate fluctuations in the northern SCS. The Core has the typical "Atlantic type" carbonate cycle, and the carbonate content is mainly controlled by the dilution effect of the South China terrestrial debris. The magnetic susceptibility is negatively correlated with carbonate content, and its value is controlled by the content of calcium carbonate in sediments. During the last interglacial period (MIS5), the sea level is high, the terrestrial materials input is dominated by a small amount of fine particles, the carbonate content is high due to the weak dilution of terrestrial materials, and the magnetic susceptibility is low due to the strong dilution of calcium carbonate. During the last glaciation (MIS2-MIS4), the sea level is reduced, the terrestrial materials input is dominated by a large number of coarse particles, the carbonate content is low due to the strong dilution of terrestrial materials, and the magnetic susceptibility is high due to the weak dilution of calcium carbonate. In the postglacial period (MIS1), the sea level gradually increased, the Core DLW3101 is gradually away from the land, and yet the calcium carbonate content in the sediments increasing with the dilution of terrestrial materials gradually decreased.