TOPOGRAPHY AND DEFORMATION MECHANISM VARIATION ALONG-STRIKE IN THE LONGMEN SHAN AND SICHUAN BASIN

The devastating 2008 Wenchuan earthquake (M 8.0) occurred on the Longmen Shan, where exhibits an unusual morphology between the Tibetan Plateau and the Sichuan basin. Our main goal of the paper is to discuss the topography and deformation mechanism variation along-strike in the Longmen Shan and Sichuan basin, and imply of these findings for regional seismic hazards. Three structural cross-sections, integrated with physical and numerical model results, show that the deformation mechanism of the Longmen Shan and Sichuan basin is mainly dominated by the Pre-Sinian and Lower Sinian over-pressured shale layers, whereas locally is controlled by the Lower Triassic Jialingjiang and Middle Triassic Leikoupo Formations salt layers, such as the Longquan and Xiongpo anticlines. Our investigates support brittle crustal thickening model for the formation and maintenance of eastern margin Tibetan Plateau that upper crustal shortening can produce the remarkable topography of the Longmen Shan between the Tibetan Plateau and Sichuan Basin without calling on lower crustal flow. We also suggest that the active faults within the Sichuan basin and southern Longmen Shan may represent a significant seismic hazard to the densely populated Sichuan basin, such events might be similar to the 2013 Lushan earthquake (M 7.0) in the southern Longmen Shan.