The easternmost Tianshan forms the eastern extremity of the modern Central Asian Orogenic Belt and represents a key locality to investigate strain propagation from the Meso‐Cenozoic plate margins to the Eurasian interior. The Tianshan as a whole has been reactivated multiple times throughout the Meso‐Cenozoic, but the extent of these reactivation events is yet to be fully understood. This study applies apatite fission track and apatite (U‐Th‐Sm)/He thermochronology to the mountain ranges of the easternmost Tianshan. Our new results suggest that the area experienced two phases of rapid cooling in the Mesozoic—during the Early to Middle Triassic and the Late Cretaceous. These cooling phases are linked to tectonic events at the distant plate margins such as the Permian to Middle Triassic closure of the Paleoasian Ocean and the Late Jurassic to Early Cretaceous Mongol Okhotsk orogeny. Fault‐controlled differential exhumation and block tilting are recorded in the distribution of apatite fission track ages across the region. Finally, we show through a combination of multiple thermochronometers and the integration of structural analysis that the easternmost Tianshan has experienced insufficient exhumation to constrain the timing of reactivation in response to the Cenozoic collision of India with Eurasia and instead records older, Mesozoic tectonic events.

Multi‐method thermochronology along the Vakhsh‐Surkhob fault zone reveals the thermotectonic history of the South Tian Shan–Pamirs boundary. Apatite U/Pb analyses yield a consistent age of 251 ± 2 Ma, corresponding to cooling below ~550–350°C, related to the final closure of the Palaeo‐Asian Ocean and contemporaneous magmatism in the South Tian Shan. Zircon (U–Th–Sm)/He ages constrain cooling below ~180°C to the end of the Triassic (~200 Ma), likely related either to deformation induced by the Qiangtang collision or to the closure of the Rushan Ocean. Apatite fission track thermochronology reveals two low‐temperature (<120°C) thermal events at ~25 Ma and ~10 Ma, which may be correlated with tectonic activity at the distant southern Eurasian margin. The late Miocene cooling is confirmed by apatite (U–Th–Sm)/He data and marks the onset of mountain building within the South Tian Shan that is ongoing today.

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