Late Quaternary sinistral strike-slipping of the Liupanshan-Baoji fault zone: Implications for the growth of the northeastern Tibetan Plateau

Abstract The Liupanshan-Baoji fault zone is one of the outermost parts of the northeastern Tibetan Plateau. Its fault behavior allows us to address one of the major questions in understanding the growth pattern of the northeastern Tibetan Plateau. Here, we present the strike-slip rates and the initiation times of two key active faults in the Liupanshan-Baoji fault zone: the East Liupanshan Fault (ELF) and Longxian-Qishan-Mazhao Fault (LQMF), to identify whether the NE Tibetan plateau grew outwards sequentially or deformed simultaneously. Based on the geomorphic marker offsets, fault ages constrained by the 14C dating, and previous studies, we first determine the average slip rates of 0.7–2.0 mm/a and 0.5–0.9 mm/a along the southernmost ELF and the LQMF. Then we estimate the total left-lateral displacements along the two faults, 4 km on the ELF and ~ 1 km on the LQMF. If the long-term slip rates on those two faults were constant during late Cenozoic time, the initiation dates of the sinistral movements would be ~3 Ma and ~ 1.4 Ma, concurrent with the changes in sediment accumulation and sizes around the nearby Cenozoic basins, as well as the development of river terraces in the northeastern Tibetan Plateau. We therefore infer that the kinematic behavior on the two faults is caused by the clockwise rotation of the Longxi Terrane. The results further highlight the two stages of tectonic deformation at 3 Ma and 1 Ma in the northeastern margin of the Tibetan Plateau.