Abstract:Dissolution and preservation of carbonate is an important part of global carbon cycle. So the study of carbonate dissolution is of great significance in exploring the mechanism of carbon cycle and understanding the mechanism of global climate change. In this paper, we analyze the carbonate lysocline depth (CLD), compensation depth (CCD) and their variation since the Middle Pleistocene by the characteristics of planktonic foraminifera, benthic foraminifera and calcium carbonate in 108 surface sediments and 4 columnar sediment samples collected from the southern part of the Yapu Trench. According to the surface sediment calcium carbonate content, abundance of planktonic and benthic foraminifera, proportion of benthic in the whole foraminifera, benthic’s cemented crust proportion and other indicators, the modern CLD in this area is located near the water depth of 3800 meters, and the CCD is about 4800 meters. The change of columnar foraminifera dissolution index indicates that the dissolution of carbonate is weakened in the glacial period with the CLD and CCD deepened; while the dissolution of carbonate is enhanced, the CLD and CCD shallowed in the deglacial phase. The carbonate content of columnar cores near the modern lysocline shows the "Pacific type" cycle characteristics, which with high carbonate content in glacial period and low in interglacial period. At the same time, there is no obvious correlation between the variation curve of paleo-productivity index and carbonate content. Therefore, it is considered that the carbonate content change in the study area is mainly controlled by dissolution, especially during the glacial-interglacial transition period since Pleistocene.