南海东北部MD05 2905站36 ka BP以来的陆源碎屑沉积特征与东亚季风的演化

在AMS14C精确定年的基础上，去除有机质、生物碳酸盐和生物硅之后，对南海北部MD05 2905站进行了陆源碎屑的粒度分析。结果显示，15.5～63.5 μm粗粒级成分的含量变化特征可用来指示东亚冬季风的变化，2～9 μm细粒级成分含量变化可用于指示东亚夏季风的变化。末次冰期以冬季风为主，全新世以夏季风为主，36 ka BP以来东亚夏季风有逐渐增强的总体趋势，但也发生多次突变现象，在全新世早期（8 500~11 200 ka BP）达到36ka BP以来的最大值，可能是在岁差周期的控制下，与较强的太阳辐射有关。

Sedimentary Characteristic of Terrigenous Clast of Site MD05-2905 in the Northeastern Part of South China Sea after 36ka and Evolution of East Asian Monsoon

Sediments with high sedimentation rate at Site MD05 2905 in the northern part of the South China Sea provide unique materials for a high resolution study on paleoenvironment. Based on precision dating of AMS14C, grain size analysis of terrigenous clast at Site MD05 2905 is studied after removing organic matter, biological carbonate and biogenic opal. The results show that 15.5~63.5μm, coarse grain size ingredients，may indicate the East Asian winter monsoon changes. And that 2 ~ 9μm，fine grain size ingredients，may be used as a proxy of evolution of the East Asian summer monsoon. The results of grain size analysis, which suggest the East Asian monsoon intensity, revealed that a winter monsoon dominated glacial regime and a summer monsoon dominated Holocene regime, and that the summer monsoon increased gradually，experienced several abrupt change events and reached to the culmination in the early Holocene（8 500~11 200 ka BP） after 36 ka. This, with control by precession periodicity, may be related with the amount of solar radiation at the highest stage which needs further study.