Initial Cenozoic Exhumation of the Northern Chinese Tian Shan Deduced from Apatite (U-Th)/He Thermochronological Data

Abstract The present topography of Tian Shan is related to the India-Asia collision, whereas mechanisms for topographic growth remain at center debate partly due poorly constrained onset timing Cenozoic tectonic deformation. Our new apatite (U-Th)/He (AHe) data in northern Chinese suggest that rapid cooling commenced 20.2±4.9 Ma along margin, which consistent with published fission-track from same area and confirms youngest component has been totally annealed. Moreover, AHe interior mountain enhanced began 28.0±2.3 Ma, slightly older than edge mountain. Although thermochronological both margin have undergone since late Oligocene-early Miocene, well preservation relict low-relief surfaces rim indicate may experienced differential exhumation Cenozoic. Combining geomorphological evidence, we propose a progressive northward model Shan. During Oligocene early compressive deformation derived collision arrived reactivate its while intense was concentrated range. Then, extended into foreland basin be initiated middle-late Miocene.