关键词: 长江江苏段, 末次盛冰期, 长江古河槽, 地质剖面

Abstract:

The section of Yangtze River in Jiangsu Province was selected as the research reach. Seven cross-sections of paleo-valley depositional sequences were established with 285 bore datum and 8 documents from the references, which were the NO.3, NO.1, NO.4 Nanjing Yangtze River Bridges, the Runyang Yangtze River Bridge, the Yangzhong Yangtze River Bridge, the Jiangyin Yangtze River Bridge and the Sutong Yangtze River Bridge. 8 age results of ¹⁴C and 1 age results of ESR were obtained through analysis of seven drilling cores samples near the Nanjing NO.4 Bridge and the Yangzhong Bridge. The results indicate that, in the Last Glacial Maximum (LGM), the incised-valley was cut down into bedrocks at the upper reach of Zhenjiang Province, and the paleo-channel of Yangtze River flows through old riverbed sedimentary facies at the down reach of Zhenjiang Province , and the paleo-valley formed partly deep cut in the Xiaguan-Qixia Mountain. The deep incised-valley at the depth of -63 m to -94 m was the Yangtze River valley during the LGM, the deep incised-valley channel was narrow and the river flowed swiftly at Nanjing reach. The width to depth ratio (\begin{array}{c}\raisebox{1ex}{$\sqrt[]{B}$}\!\left/ \!\raisebox{-1ex}{$H$}\right.\end{array} )at Nanjing reach was small than that at Zhenjiang reach, which gradually increased along downstream. The bifurcation paleo-valley system of the Yangtze River were formed below Yangzhong. It is also found that the sediments of the paleo-valley in Jiangsu reach consist of an obvious rhythm from graver and coarse sand to fine sand from bottom to top and the sedimentation was gradually fined along downstream.

Key words: the Yangtze River in Jiangsu Province, the Last Glacial Maximum, the paleo-vallye of the Yangtze River, stratigraphical section