Late Cenozoic Convergence Between the Pamir and the Tianshan Revealed by Low‐Temperature Thermochronology

Abstract

The Cenozoic India–Eurasia collision drove widespread deformation across Central Asia, culminating in northward indentation of the Pamir and its eventual contact with the South Tianshan. However, the timing and kinematics of Pamir–Tianshan convergence, as well as its influence on regional topography and climate, remain debated. Here, we report >200 new apatite and zircon (U‐Th‐Sm)/He and apatite fission‐track dates from 49 samples collected from the North Pamir–South Tianshan convergence zone in the westernmost Tarim Basin, NW China. Thermal history modeling of these data and quantitative estimates of cooling onset reveal a protracted, spatially progressive history of deformation and exhumation since the late Eocene. Localized deformation and exhumation were active within the North Pamir and South Tianshan hinterlands during the late Eocene–early Oligocene (∼35–30 Ma). During the middle Miocene (∼15–10 Ma), deformation initially propagated basin‐ward, marked by the activation of southward‐ and northward‐verging frontal thrust systems of the North Pamir and South Tianshan, respectively. Continued basin‐ward propagation of deformation during the late Miocene (∼10–5 Ma) resulted in structural contact between the opposing North Pamir and South Tianshan thrust systems, accompanied by localized out‐of‐sequence deformation that persisted into the Pliocene–Quaternary. Progressive deformation and associated surface uplift may have contributed to increasing topographic restriction of westerly moisture transport into the Tarim Basin, and thereby to the establishment of the Taklimakan Desert. Together with existing paleoclimate records, our results support the interpretation that regional tectonic processes, acting in concert with global climatic forcing, likely played a dominant role in the long‐term aridification of Central Asia.