Geological and geophysical evidences of late Quaternary activity of the range-front fault along the mid-segment of the Longmen Shan thrust belt

作者：Ren Jun-Jie^*; Xu Xi-Wei; Sun Xin-Zhe; Tan Xi-Bin; Li Kang; Kang Wen-Jun; Liu Bao-Jin

来源：Acta Geophysica Sinica, 2012, 55(6): 1929-1941.

DOI：10.6038/j.issn.0001-5733.2012.06.014

• Mid-segment of the Longmenshan thrust belt
• Range-front fault
• Faulted landform
• Trench
• Eastern Tibet

The existence and the latest active time of the range-front fault along the mid-segment of the Longmen Shan thrust belts are controversial for a long period. Petroleum seismic reflection and high-resolution shallow seismic reflection profile discovered the existence of the range-front fault which offset the Quaternary strata. Based on detailed field observation, we found that there is an obvious linear feature along the mid-segment of the Longmen Shan front and the range-front fault that displaced the late Quaternary alluvial terrace. Trench log indicates that a surface-rupture event occurred before similar to 1500 a along the range-front fault. Differential GPS surveying and dating of alluvial terrace show that the range-front fault during late Quaternary had a vertical slip rate bigger than 0.36 mm/a, approximately equivalent to that along the main faults of the Longmen Shan thrust belts, which demonstrates that the range-front fault also took an important role in accommodating the deformation of the Longmen Shan thrust zone. This study not only provides the fundamental data for seismic hazard assessment of the Chengdu Plain, but is helpful for the overall understanding of uplift mechanism of east Tibet.

• 出版日期2012-6
• 单位中国地震局