青藏高原可可西里盆地始新世-渐新世气候转型事件磁性地层学研究

始新世-渐新世气候转型事件（Eocene-Oligocene Transition，EOT）标志着地球由“温室环境”进入“冷室环境”。长期以来，全球EOT事件研究记录主要集中在海洋；我国境内研究地点集中分布在青藏高原周边盆地中，高原内部缺乏研究记录。另外，目前的研究基本都指示EOT时期气候特征为冷干。申请人前期在青藏高原可可西里盆地沱沱河剖面开展了部分地层年代学工作，结果表明该剖面地层时代不仅包含EOT时间段，而且很大可能性在EOT界线处沉积相由河流相过渡为湖泊相，向湿润方向转变，与全球此时冷干的气候特征相比具有显著差异性。为什么以及是否真存在这种差异性，为解决这些问题，本项目拟对沱沱河剖面开展高分辨率的磁性地层学研究，确定可可西里盆地沱沱河剖面的地层年龄，明确EOT气候事件在剖面中的具体位置，然后结合理化分析讨论剖面记录的EOT气候事件变化的细节。

The Eocene-Oligocene Transition (EOT) symbolizes the Earth’s climate transitioned from “greenhouse” conditions to “coldhouse”. For a long time, the global EOT research records are mainly concentrated in the ocean. In China, the research is concentrated in the basins around the Tibetan Plateau, and there is still no data about EOT in the plateau interior. In addition, the current research basically indicates a cold and dry climate characteristic during the EOT period. The applicant carried out part of the stratigraphic work in the Tuotuohe section of the Hoh Xil Basin, Tibetan Plateau in the early stage. The results show that the stratigraphic age of this section not only includes the EOT period, but it is highly likely that the sedimentary facies changes from fluvial to lacustrine (wet direction) at the boundary of the EOT, which is significantly different from the global cold and dry climate characteristics at this time. Why and whether there are such differences? In order to solve these problems, this project intends to carry out high-resolution magnetostratigraphic research on the Tuotuohe section, determine the stratigraphic age of the Tuotuohe section, clarify the specific location of the EOT climate event in the section and then discuss the details of the changes in the EOT climate event recorded by the section in conjunction with physical and chemical analysis.