|
Abstract:
Study on geomorphologic characteristics and forming reason of the upper reaches of the Fujiang River basin are conducive to revealing the regional difference of neotectonic movement on eastern margin of Tibetan Plateau since the Late Cenozoic. Hydrological analysis on the module of ArcGIS was applied to extract the Fujiang drainage networks and obtained 36 drainage sub-basins along the both sides of the river. Statistical analysis of the geomorphic parameters (e.g. areas, perimeters, total channel lengths, branching ratios, evolutional stages) of the sub-basins was also conducted based on this module. The results showed that there was a significant difference on the both sides of the main channel. The analysis on the correlation between river incision and controlling factors such as tectonic movement, rock types, precipitation characteristics shows that precipitation condition and lithology are not the main controlling factors of the development of sub-basins. It shaped a special geomorphic pattern in the upper reaches of Fujiang River basin, and the main controlling factors leading to the geomorphic evolution could be the asymmetrical distribution of terrain and the difference of degree of ore-rock fragmentation caused by the fault activity. In addition, the distribution of main stream of Fujiang River shows two characteristics:the main stream of Fujiang River is curved synchronously along the fault due to right-lateral (or left-lateral) strike-slip movement of Xueshan Fault and Beichuan-Yingxiu Fault and Pengxian-Guanxian Fault. The flow direction of main stream of Fujiang River changed from northwest-southeast to near south on the northern side of Beichuan-Yingxiu Fault. The main reason is that the regional dextral strike-slip activity of the three main faults in Longmenshan fault zone drives the corresponding dextral movement of the materials in this area, which causes the main stream of Fujiang River under the control of dextral action of the fault to change direction.
|