The Study Of The Quaternary Environment Of The Dongting Lake And The Upper Xiangjiang

Abstract The Dongting Lake which is the second biggest freshwater lake locates in the middle part of the Yantze River. The Xiangjiang River is the biggest river with biggest drainage area in Hunan Province, and it also is the most important distributary in the Dongting Lake. The Dongting Lake is a wellknown land flowing with milk and honey, while the Xiangjiang River basin, especially the lower part, is the most popular-densely area with the most advanced in politics, economic and culture. Therefore, the deep study of quaternary environment of this area is of great importance in science and realism. The thesis tries to analyse an study the quatemary environment of the Dongting Lake and the Xiangjiang basin in the following aspects: 1 .The physical geography survey of the Dongting Lake, including the geomorphological characters, geomophological types and subarea, climate, hydrology, etc, with a simple introduction of the geography background of the study area. 2.The Dongting Basin has sinked since the Late Yanshan Movement for a long time, where the Jianghan Sedimentation Belt is the hypo-grade formation unit of the Yantze Terra. The thesis analyse the Dongting Lake geology formation base from the pre-quaternary stratum distribution, magma rock, geology formation; 3 .The quatemary stratum in the Dongting Lake is famous for large area on the earth, complete stratum stratum order, great thickness. The change of the stratum is the thickness in the center of the basin is the highest while that in the verge is relatively thin. The thesis analyse the Dongting Lake quatemary stratum form the lower Renovate, the middle Renovate, the upper Renovate, the Full-fresh. 4.The Dongting Basin has changed greatly in Quatemary. The thesis analyse the Dongting Lake Quaternary Basin characters in the lower Renovate, the middle Renovate, the upper Renovate, the Full-fresh. The lake basin changed from small to large. from large to small and from small to large because of the crust subsiding since quaternary, the new construct rupture movement and the climate environment changing. i.e. the lake basin changed from small to large at first and from large to iii ASTERS 555W S ____ small in the Renovate: in the early scheduled time of Huatian 梸 (enlarging) in the late scheduled time 梸 (enlarging) Miluo棐~ (enlarging) Xinkaipu梸- (enlarging) (enlarging) Baishajing梸 (shringking) Mawangdui-* (shrinking) Baishuijing. A plain emerged at the end of Baishuijiang. 5.The Xiangjiang River is the longest river in Hunan Province with the largest basin in the same area. It抯 the important outdoor observation field in this thesis because of dense population and advanced economy and culture in this area where human beings activities is frequent and the reciprocity between the human beings and the physical environment is intense and profound. For three times I visited Changsha and Zhuzhou for the Xiangjiang River Steps under the supervised of Doctor Yi Chaolu from the Institue of Geodesy of China Institue of Science. In the meantime, I depicted sampled the typical sections and I carried out the granule analysis for the samples.