Late Miocene rapid exhumation in the West Kunlun range: Insights into Tibetan Plateau growth and India-Asia lithospheric collision

The West Kunlun (WKL) orogen, a pivotal boundary on the western Tibetan Plateau, records the dynamic interplay between northward underthrusting Indian lithosphere and the Tarim craton. Despite its significance, the exhumation history and mechanisms of plateau growth in this region remain contentious. Here, apatite fission-track (AFT) and (U-Th)/He (AHe) thermochronology data from three bedrock elevation transects across the WKL were used to refine the Miocene exhumation processes in the region. Our results reveal a regionally consistent two-phase acceleration in late Miocene exhumation at ca. 11−10 and ca. 7−6 Ma. Integration with regional thermochronologic, magmatic, and seismic data shows a systematic younging of cooling ages and (ultra)potassic magmatism toward the WKL, alongside increasing exhumation rates. These trends reflect outward plateau expansion driven by progressive indentation of the Indian plate into Asia. This culminated at ca. 11−10 Ma, when the cratonic Indian slab directly impinged the Tarim craton, as evidenced by rapid surface uplift and the formation of ca. 10 Ma and younger (ultra)potassic magmas in the WKL orogen. Our findings highlight the coupling between deep lithospheric processes and surface deformation, providing critical constraints on the timing of the India-Tarim collision and the mechanisms driving plateau growth along the northwestern margin of the Tibetan Plateau.