Slip Rate of Yema River-Daxue Mountain Fault since the Late Pleistocene and Its Implications on the Deformation of the Northeastern Margin of the Tibetan Plateau

The slip rate of Yema River-Daxue Mountain fault in the western segment of Qilian Mountains was determined by the dated offset of river risers or gullies. Results indicate that the left-lateral fault slip rate is 2.82 +/- 0.20 mm/a at Dazangdele site, 2.00 +/- 0.24 mm/a at Shibandun site, and 0.50 +/- 0.36 and 2.80 +/- 0.33 mm/a at two sites in Zhazihu. The ideal average slip rate of the whole fault is 2.81 +/- 0.32 mm/a. The lower slip rate confirms part of the displacement of Altyn Tagh fault was transformed into an uplifting of the strap mountains in the western segment of Qilian Mountains, whereas another part transformed into sinistral displacement of Haiyuan fault. This study illustrates that the slip of large strike-slip faults in the northeastern margin of the plateau transforms into crust thickening at the tip of the fault without large-scale propagation to the outer parts of the plateau.