Geomorphic indices of rivers and drainage in China’s Longmen Shan Fault zone and their implications for regional tectonic activity

Abstract

Theoretical models suggest that active tectonic deformation can impose a primary control on the patterns and styles of channels. The Longmen Shan Fault zone, which is located on the eastern margin of the Tibetan Plateau, has experienced strong tectonic activity, including uplift and strike-slip phases of tectonic movements. Here, we adopt ASTER-GDEM2 data and utilise a stream-power incision model to extract information on the spatial characteristics of differential tectonic movements. Analysis of the patterns and styles of 37 channels exhibits systematic differences in the channel steepness indices and the river sinuosity values along the strike of the Longmen Shan Fault zone. Our primary results demonstrate that the normalised channel steepness indices in the southern part of the Longmen Shan Fault zone are much higher than those in the northern part, where the river sinuosity values are much lower. Comparisons between the five drainage basins reveal that the river systems in the middle southern part of the fault zone are mainly controlled by tectonic uplift and thrusting, whereas the river systems in the middle northern part of the fault zone are mostly attributed to right-lateral strike-slip movement.