Abstract:

Bangong Lake area in western margin of the QinghaiTibet Plateau is a typical part of the western syntaxis, and also is the important region of research on the QinghaiTibet Plateaus tectonic movement, geomorphic evolution and environmental changes since the Middle Pleistocene. Based on the results of geological surveys, by means of the satellite remote sensing image interpretation and the analysis of digital elevation models, this paper mainly studies the brief characteristics of neotectonics and its coupling with the terrain and geomorphic features of the area. The results indicate that Bangong Lake areas faults can be divided into four groups which are nearly EW, NW, NE and NNE, in those, nearly EW is the main fault, and most of these fault basins have the features of pullapart. Late Cenozoic stratigraphy grows in the region, particularly the Quaternary alluvialdiluvial fans and lake sediments widely distribute, which are linearly developed and controlled by the faults, and lacustrine and alluvial terraces are also developed, which indicate the period of tectonic uplift in the region. The isotopic ages of calcitic sediments are (23.8±2.3) kaBP, (33.9±4.0) kaBP, (78.0±8.0) kaBP on the terraces with heights of 62 m, 65 m and 98 m above lake level near Wujiang at the north bank of Bangong Lake. The earthquakes occurred frequently in this area. According to the statistics, the magnitude of 303 earthquakes are more than Ms 4.0 and 7 earthquakes of those are more than Ms 6.0 since 1970. The topography and geomorphology characteristics of the study area are mainly middlelarge undulating mountain (5002,500 m terrain undulation). Plains and plateaus also less developed, which indicates that the stronger erosion of surface leveling process associating with the crust tectonic uplift since the Middle Pleistocene.

Key words: Bangong Lake area, remote sensing interpretation, geomorphology districts, neotectonics