Relief history and denudation evolution of the northern Tibet margin: Constraints from 40Ar/39Ar and (U–Th)/He dating and implications for far-field effect of rising plateau

• 40Ar/39Ar and (U–Th)/He age profile from E. Kunlun range are obtained.
• A minimum exhumation of ~ 11.7–14.0 km since ~ 220 Ma is recognized.
• A rapid exhumation event along the Eastern Kunlun at ~ 40 Ma is recognized.
• Low relief at ~ 50 Ma, high relief at ~ 40 Ma, and higher denudation rate since ~ 40 Ma are obtained.
• Synchronous deformation with the onset of collision model is supported.

How does the rising Tibetan Plateau affect its peripheral region? The current understanding of the mechanism of orogenic plateau development is incomplete and thus no consensus yet exists in this regard. However, our new 40Ar/39Ar and (U–Th)/He dataset presented in this study may shed some light on this issue. 40Ar/39Ar dating, on two vertical transects from the massif between Nuomuhong and Golmud, indicates that the Eastern Kunlun Range was built-up and exhumated during the later Triassic initially, and a minimum overburden of ~ 11.7–14.0 km has been eroded since ~ 220 Ma. (U–Th)/He age–elevation relationships (AERs) indicate a rapid exhumation event at ~ 40 Ma following a long period of slow exhumation phase from late Mesozoic to early Eocene time. In this study, two scenarios – one assuming a single stage and the other assuming multiple stages of evolution history – are modeled. Modeling of a multiple stage scenario is reasonable and is able to reflect the “actual” situation, which reveals the entire denudation and relief history of the northern Tibet from late Mesozoic to the present time. After prolonged denudation before 50 Ma, a low topography (~ 0.17 times the relief of the present) developed by 50 Ma with an erosion rate of 0.013-0.013+ 0.025 mm/yr. The highest relief (~ 1.82 times the relief of the present) of the Cenozoic time came into being at 40 Ma with an erosion rate of 0.052 ± 0.025 mm/yr, which was possibly a result of the collision between India and Eurasia. Subsequently, the relief steadily decreased to the present level due to continued denudation. This suggests that deformation propagation from the continued convergence boundary between India and Eurasia was insignificant after the construction of the highest relief. This observation is broadly consistent with published accounts on the stratigraphic, cooling, and faulting histories of the northern Tibet margin.