Late cenozoic right-lateral movement along the Wenquan fault and associated deformation: Implications for the kinematic history of the Qaidam Basin Northeastern Tibetan Plateau

Bounded by the NE-trending Altyn Tagh fault on the northwest, the northeastern margin of the Tibetan Plateau consists of the Qihan Shan belt, Qaidam Basin, west Qinling belt, and east Kunlun belt. In the area where these tectonic units join, the NW-trending Wenquan fault between the Qaidam Basin and west Qinling belt contains clear evidence of active right-lateral movement. At the northern and southern ends of the fault, right-lateral movement has been transferred to NE-SW crustal shortening. Right-lateral movement was initiated in late Miocene to Pliocene time and has similar to20 km of total displacement, which yields an average slip rate of similar to4 mm/yr. Uplift of the Wahong Shan, bounded by the Wenquan fault on the east, resulted from en echelon thrusting and folding associated with right-lateral movement. The right-lateral movement along the Wenquan fault suggests that displacement occurs between the tectonic units within the northeastern margin of the plateau and that the Qaidam Basin is underlain by a more rigid basement that has moved northward relative to the west Qinling belt to the east. The right-lateral Wenquan fault and left-lateral Altyn Tagh fault can lie regarded as conjugate structures, and accommodated the northward indentation of the Qaidam Basin into the Qilian Shan belt. The fact that the Wenquan fault has a slower slip-rate than the Altyn Tagh fault Suggests that the northward movement of rigid basement of the Qaidam Basin must have a component of clockwise rotation relative to the Qihan Shan belt. The west Qinling belt pinches out westward between the Wahong Shan and Qilian Shan belt, implying that it may have undergone some eastward extrusion due to the N-S convergence between the Qaidam Basin and Qilian Shan belt.