Eastward Variations in Slip Rates Along the West Qinling Fault: Implications for Limited Lateral Expansion of the Northeastern Tibetan Plateau

Abstract

The expansion of the northeastern Tibetan Plateau is accommodated by several major active strike‐slip faults developed in the region, which provide key insights into the late Cenozoic tectonic deformation and material transport patterns in this area. However, as one of the crucial strike‐slip faults coordinating the lateral extrusion of crustal material along the northeastern margin of the plateau, the variations in slip rate and the tectonic transition at the eastern termination of the West Qinling Fault (WQLF) remain unclear. Based on detailed geological investigations and chronological constraints, this study quantifies the Late Quaternary average left‐lateral slip rates of the Zhangxian segment and the Wushan–Gangu segment in the central segment of the WQLF as 2.58 + 0.16/−0.15 mm/yr and 2.03 + 0.27/−0.25 mm/yr (95% CI), respectively, whereas the average slip rate of the eastern Tianshui–Baoji segment decreases to 1.15 + 0.13/−0.10 mm/yr, showing a stepwise decrease along the fault. Unlike other major strike‐slip faults in the northeastern Tibetan Plateau, whose slip rate decay toward fault terminations is typically converted into tectonic uplift, the eastern termination of the WQLF exhibits relatively gentle topography, and the gradual eastward decrease in slip rate from its central segment is primarily controlled by extensional splays formed during its eastward propagation. At the regional scale, the eastern segment of the WQLF and the Qishan–Mazhao Fault along the southwestern margin of the Ordos Block together form a shear–extensional tectonic zone, collectively accommodating the limited eastward transport of plateau material into the Weihe Basin.