Tectonic deformation and kinematics of fluvial terraces marking the northeastern margin of the Tibetan Plateau

Abstract

This paper reports on a study of the geometry and kinematics of numerous active faults within the Qilian Shan-Hexi Corridor area, which has provided valuable insights into regional deformation patterns. The Jintanan Shan faults are located at the northern end of the Hexi Corridor. In the Jintanan Shan range, five gaps have been excavated by rivers originating from the Qilian Shan, and have well-preserved fluvial terrace sequences in them, with evidence for deformation. Terrace profiles measured by the Differential Global Positioning System and ‘Structure-from-Motion’ processing were used to constrain the fold deformation, and a fault-related fold model was applied to estimate mountain growth and deformation kinematics. Using the geometry of the faults, as well as optical stimulated luminescence (OSL) dating and ¹⁰Be exposure dating control for the terraces, the rates of crustal shortening, vertical uplift and fault slip show estimated ranges of 0.19–1.35 mm/a, 0.21–2.14 mm/a and 0.29–2.27 mm/a, respectively, since ∼159 ka. The geometry and kinematics of the Jintanan Shan faults enable us to estimate the deformation pattern in the northern Hexi Corridor, which indicates that this area is undergoing northeastward compression relative to the northern Tibetan Plateau (Qilian Shan). Active faults in the region are principally driven by the northeastward push of the Tibetan Plateau, with the eastward extension of the Altyn Tagh fault probably playing a coordinated role.