Differential Mountain‐Building in the South Tian Shan Revealed by Multi‐Spatiotemporal Foreland Deformation

Abstract Understanding how spatially variable mountain‐building processes proceed within large intracontinental orogens provides critical insights into continental tectonics and regional paleoenvironmental evolution. Here, we address this issue in the central South Tian Shan (cSTS), a key transitional segment between the well‐studied eastern and western South Tian Shan. This region is characterized by extensive glaciation, peaks exceeding 6,000 m, complex drainage patterns, and the active range‐front Maidan Fault, highlighted by the recent M w 7.0 Wushi earthquake. We integrate seismic profile interpretation, kinematic forward modeling, and geomorphic analysis to reconstruct the multi‐spatiotemporal deformation history of the Eastern Wushi foreland. Our results show that basinward propagation of the Wushi foreland thrust system began at ∼5.3 Ma, significantly later (by 10–15 Ma) than in adjacent segments. GPS velocity data and deformed Late Quaternary geomorphic surfaces at the Wushi foreland indicate ongoing activity along the eastern Maidan Fault, with total active shortening across the Eastern Wushi foreland estimated at ∼2.0–3.3 mm/yr over the past ∼30 Kyr. Together, these findings suggest an active transpressional mountain‐building regime in the cSTS, characterized by oblique slip along the range‐front Maidan Fault, coeval foreland deformation, and potential shear thickening of the orogenic wedge. Our results reveal that the South Tian Shan accommodates crustal shortening through spatially variable mountain‐building processes, highlighting the coexistence of transpressional and in‐sequence thrust wedge processes across the range. This differential mountain building provides new insights into the evolution of active intracontinental orogens on a thousand‐kilometer scale.