Timing and mechanisms of Tibetan Plateau uplift

The timing of the initial India-Asia collision and the mechanisms that led to the eventual formation of the high (>5 km) Tibetan Plateau remain enigmatic. In this Review, we describe the spatio-temporal distribution and geodynamic mechanisms of surface uplift in the Tibetan Plateau, based on geologic and palaeo-altimetric constraints. Localized mountain building was initiated during a Cretaceous microcontinent collision event in central Tibet and ocean-continent convergence in southern Tibet. Geological data indicate that India began colliding with Asian-affinity rocks 65-60 million years ago (Ma). High-elevation (>4 km) east-west mountain belts were established in southern and central Tibet by similar to 55 Ma and similar to 45 Ma, respectively. These mountain belts were separated by <= 2 km elevation basins centred on the microcontinent suture in central Tibet, until the basins were uplifted further between similar to 38 and 29 Ma. Basin uplift to >= 4 km elevation was delayed along the India-Asia suture zone until similar to 20 Ma, along with that in northern Tibet. Delamination and break-off of the subducted Indian and Asian lithosphere were the dominant mechanisms of surface uplift, with spatial variations controlled by inherited lithospheric heterogeneities. Future research should explore why surface uplift along suture zones - the loci of the initial collision - was substantially delayed compared with the time of initial collision.