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The Keping fold-and-thrust belt (FTB) is located along the southern foreland of the Chinese Tian Shan, consisting of 3–6 rows of E - to NE-trending thrusts. Determining the time of thrusting and folding within the Keping FTB is crucial to understand the process and characteristic of tectonic deformation along the southern Tian Shan foreland. Here, we present new deformation ages of four thrusts within the Keping FTB by using the apatite (U Th)/He thermochronometer. Based on analyses of 59 single-grain apatite (U Th)/He ages of 13 sandstone samples collected from the hanging-walls of the four thrusts, the deformation ages of two thrusts located at the northern part of the western Keping FTB were constrained to be ~12 Ma and ~ 11 Ma, respectively; while those of two thrusts located at the southern part of the eastern Keping FTB were interpreted to be ~14 Ma and ~ 13 Ma, respectively. The above deformation ages, together with previous studies, suggest that the Cenozoic deformation across the southern Tian Shan foreland initiated at ~16–12 Ma, and the propagation process of the Keping thrust system is laterally non-synchronous. Additionally, the million-year-scale crustal shortening rates of the Keping FTB were recalculated to be ~2.2–3.9 mm/yr in its western segment and ~ 1.3–3.6 mm/yr in its eastern segment, based on the new age constraints of initial tectonic deformation and published shortening estimates. • The Cenozoic deformation within the Keping thrust belt initiated at ~16–12 Ma. • Propagation processes of the Keping thrust system are laterally diachronous. • Tectonic scale shortening rate of the Keping thrust belt is ~1.3–3.9 mm/yr. [ABSTRACT FROM AUTHOR]

Forming the northwestern branch of the Chinese Tian Shan, the Keguqin mountain located north of the Yili basin is characterized by Mesozoic relict landscapes and active faults, which recorded abundant information of long term tectono-geomorphologic evolution of the Tian Shan mountain range. However, the post-Jurassic deformation history of the Keguqin mountain is unclear. In this study, we applied apatite fission track, apatite (U Th)/He and geomorphologic analyses to reconstruct the landscape evolution of the Keguqin mountain and the northern Yili basin. Our results suggest that this region underwent three stages of accelerated cooling/exhumation in the Permian, Late Triassic-Jurassic and Cretaceous. The Permian cooling event likely reflects post magmatic cooling related to the Paleozoic orogeny of the Tian Shan. Late Triassic-Jurassic exhumation is possibly a far field response of the Qiangtang collision. The Cretaceous differential exhumation in the study area was controlled by activation of the Kashihe fault zone and secondary faults. As the Cretaceous cooling is widely observed in the vast Central Asia region, northern Tibet and Southern Pamir, and coeval with the Mongol-Okhotsk orogeny, Qiangtang collision and Karakorum collision. It is difficult to decipher the tectonic drive of the Cretaceous activation of the Kashihe fault zone. Relict landscapes in the Keguqin mountain were firstly established after the Paleozoic, slightly exhumed during the Cretaceous, and were uplifted and tilted by Late Cenozoic deformation. The latest uplift magnitude of the Keguqin mountain is estimated to be ∼250–500 m and ∼ 380–430 m of the hanging wall of the Kashihe fault zone and the Keguqin fault, respectively. • The Keguqin mountain has experienced three stages of cooling/exhumation in in the Permian, Late Triassic-Jurassic and Cretaceous. • The Late Triassic-Jurassic exhumation of the Keguqin mountain was probably far field reponse of the Qiangtang collision. • The Cretaceous differential exhumation represents the reactivations of the Kashihe fault zone. • The latest uplift magnitude is estimated to be ∼250–500 m and ∼ 380–430 m on the hanging wall of the Kashihe fault zone and the Keguqin fault, respectively, in the Keguqin mountain. [ABSTRACT FROM AUTHOR]