Temporal and Spatial Variations in Late Quaternary Slip Rates Along the Daliangshan Fault Zone in the Southeastern Margin of the Tibetan Plateau Based on High-Resolution Topographic Data

The Daliangshan Fault Zone (DLSFZ) constitutes a key segment of the Xianshuihe–Xiaojiang Fault System (XXFS) and exerts fundamental control on the eastward extrusion of the Sichuan–Yunnan Block (SYB). In this work, we present new slip rate determinations at three key sites (Tekoujiagu, Yeer, Damulo) along its middle-southern segments using UAV-based high-resolution topography and OSL dating. Results yield late Quaternary slip rates of 4.5 ± 1.4, 3.7 ± 1.1, and 5.5 ± 1.0 mm/a, respectively. Combined with previous data, the slip rate is 1.5–3.1 mm/a in the northern segment, 1.36–4.3 mm/a in the middle and 2.5–4.5 mm/a in the southern segment, which exhibits a spatial pattern of “higher in the south, lower in the north, with transition in the middle”. Temporal evolution suggests increased slip rates from the Late Pleistocene to Holocene. These characteristics indicate that the DLSFZ is a heterogeneous deformation system, where strain focusing on the southern segment reflects the block’s eastward escape constrained by the rigid Sichuan Basin (SB). Thus, the DLSFZ, especially its southern segment, serves as a key structure regulating crustal extrusion at the southeastern margin of the Tibetan Plateau (TP).