国际大洋发现计划航次在南海深水区发现广泛分布的独特中新世红层沉积物，表明南海沉积环境发生重大变化。但红层的成因和南海深水沉积环境变化规律仍不清楚。本研究计划采用IODP367/368航次U1499站红层沉积与U1505站远洋沉积样品作为研究材料，通过钙质超微化石生物地层鉴定，细化中新世钙质超微化石生物地层分带方案，建立红层沉积综合地层年代模式；通过钙质超微化石属种定量分析、形态重量分析、氧碳同位素分析和Sr/Ca比值分析，结合沉积物碳酸钙含量、有机碳含量、粒度分析方法，重建中新世南海古海洋环境与碳循环的演变历史，包括海洋上层水体结构，初级生产力，碳酸盐补偿深度与海水碳酸盐系统变化，重点分析红层形成前后南海古海洋沉积环境的区域差异，探讨南海钙质超微化石对中新世气候变化事件的响应机制，为解释红层的成因和气候变化机制提供科学依据。

The International Ocean Discovery Program expeditions discovered the unique red-bed sediments from the Miocene widely distributed in the deep waters of the South China Sea (SCS), indicating a major change in the sedimentary environment of the SCS. However, the genesis of the red-bed and the sedimentary variations of the deep water in the SCS are still not clear. The study samples are composed of the red-bed deposition from U1499 site and pelagic sediment from U1505 site, which were retrieved during IODP 367/368 expeditions. This study plans to refine the calcareous nannofossil biostratigraphic zones and establish the age model of the red-bed sediments by calcareous nannofossil biostratigraphy identification. This study also plans to reconstruct the Miocene evolution history of paleoceanographic environment and the carbon cycles in the SCS, including the upper ocean water structures, primary productivity, carbonate compensation depth and seawater carbonate system changes, by using quantitative species analysis, morphological analysis, oxygen/carbon isotope analysis and Sr/Ca ratio analysis of calcareous nannofossils, combined with sediment carbonate content, organic carbon content and particle-size analysis. We will focus on the regional differences of the paleoceanographic environment variations before and after the formation of the red-bed. The processes and response mechanism of calcareous nannofossils to the Miocene climatic change events will be explored, which can provide significant and newly evidence for better explaining the genesis of the red-bed and the mechanisms of climate change.