Late Quaternary left-lateral strike slip rate along the Anninghe-Zemuhe Section of the Xianshuihe-Xiaojiang Fault System and its implication to the clockwise block rotation of the SE margin of the Tibetan Plateau

Crustal material eastward extrusion from the Tibetan Plateau is closely related to the strike-slip faults in the SE margin of the Tibetan Plateau. The left-lateral strike-slip Xianshuihe–Xiaojiang fault system (XXFS) is the most active and the largest-scale one. The slip rates along the XXFS is crucial for unraveling the kinematics of the SE margin of the Tibetan Plateau. The central section of the XXFS, also known as the Anninghe–Zemuhe section, was poorly researched owing to its inaccessibility, a lack of high-quality quantitative age data, as well as questionable displacement determination and methodology. In this study, we adopted high-resolution topographic data (terrestrial laser scanning) and high-accuracy dating methods (OSL and 14C) to obtain more reliable slip rates of Anninghe Fault and Zemuhe Fault. The late Quaternary slip rates of Anninghe Fault and Zemuhe Fault were constrained to be 6.9±0.6 mm/a and 11.2±0.4 mm/a, respectively. A large of rate statistics was also conducted along the XXFS. We found that the slip rate of the XXFS is in a narrow range of 12–15 mm/a (slightly increasing from north to south) after taking the Daliangshan Fault into account. Combined with the analysis of the relationship between the active faults and block rotation, we proposed that the uniform high-speed strike-slip along the Xianshuihe–Xiaojiang Fault System largely constrains the clockwise rotation of the SE margin of the Tibetan Plateau.