Exploring the timing and mechanism of the elevation of the Tibetan plateau

A research team led by Prof. Ding Lin of the Institute of Tibetan Plateau Research of the Chinese Academy of Sciences has systematically explained the differential upward process and associated deep dynamic mechanism of the Tibetan Plateau since the Cretaceous Period.

The review article was published in Nature Reviews: Earth and Environment on July 28.

The elevation of the Tibetan Plateau is one of the most important Cenozoic geological events in the world. However, the mechanisms of continental lithospheric deformation and spatial and temporal changes in surface height on the Tibetan Plateau during the continental collision between India and Asia are still unclear.

In recent years, with the accelerated generation of quantitative paleo-elevation data, scientists have gradually realized that the plateau is characterized by differential uplift, and that the uplift time in some areas is earlier or later than previously believed, and none of the existing dynamic models can fully reflect the plateau lifting process.

Cretaceous Tectonism and Initial Mountain Growth

“A complete evolutionary model of the Tibetan plateau needs to account for the heterogeneity of paleogeomorphology and lithospheric heterogeneity from Asia during tectonic events prior to the Indo-Asian collision, which is essential for understanding the differential elevation of the plateau,” said Prof. Thing .

Through detailed analysis of Cretaceous evidence on the Tibetan Plateau, the research team proposed that the collision of the Lhasa-Qiangtang terrane and subsequent northward subduction of the Lhasa lithosphere led to the initial growth of the Watershed Mountains; the ongoing subduction of the Neo-tethys Oceanic Plate uplifted the Gangdese Mountains above sea level ~95 million years ago and formed the Andean-type Gangdese Mountains, but the extent of the surface uplift has yet to be quantified.

Time and mode of the first India-Asia clash

The timing and mode of the collision of the Indo-Asian plates are key to limiting the extent of the surface uplift and the deep dynamics of the plateau. Current hypotheses for the closure history of the Neo-tethys ocean and the first collision of Indo-Asia include the Great Indian Basin model, the intraoceanic subduction model, and the single-stage subduction collision model. These hypotheses make very different predictions about the size of Greater India (the part of India that sank and disappeared under the Tibetan Plateau) and the timing of the first collision between India and Eurasia.

However, all these models are based on one important piece of evidence first discovered by Prof. Ding’s team, the foreland basin formed by the collision between India and Eurasia, which began to take origin from the Gangdese 65 to 59 million years ago. arc area, indicating that the clash between India and Eurasia had already begun by then. Therefore, the review points out that the single-stage subduction collision model is the simplest and the model supported by geological evidence to explain the collision between India and Asia.

Cenozoic differential uplift history of the Tibetan Plateau and its dynamic mechanism

By combining the available quantitative paleolatitude results and in-depth dynamic evidence, the research team further restored the history of surface uplift and lithospheric evolution of the Tibetan Plateau from about 60 million years ago to the present day, suggesting that the different orogenic belts of the Tibetan plateau elevate different histories. About 45-40 million years ago, after the breakup of the Neo-Tethys Ocean Plate, the more buoyant Indian lithosphere clamped horizontally northward, activating the bonding zone to the north and south of the Qiangtang body to undergo intra-subduction , creating the watershed Mountains that rise to a height of 5000 m.

At that time, the Central Tibetan Valley between the Gangdese Mountains and the Watershed Mountains, the Himalayan mountain in southern and northern Tibet remained at low elevations. The paleo-topography of Tibet presented as “Two high mountains wedged a low land valley.” About 40-30 million years ago, Lhasa’s lithosphere was dismantled beneath the Central Tibetan Valley, and a variety of coupled deep geodynamic processes, such as upper crust shortening, magma inflation, and upwelling, cause the Central Tibetan Valley to be lifted to 4500 m. About 25-15 million years ago, as a result of the continuous subduction of the Indian continent, the Indian continental lithosphere under the Himalayas and the Asian continental lithosphere under the Kunlun Mountains of northern Tibet were successively subdued, and the Himalayas and the Kunlun Mountains were successively raised to their modern heights, and the plateau in the modern sense was formed. However, the uplift history of the northern region is still uncertain and needs to be verified by more quantitative paleo-elevation data.

Contemporary India underthrusting

Geophysical evidence reveals that the present Indian and Eurasian lithosphere underwent various geodynamic behaviors ranging from horizontal wedges to steep subduction, plate rupture, fracturing and delamination. This indicates that similar processes occurred continuously during the Cenozoic India-Asia continental collision, culminating in the spatial and temporal variability of tectonic deformation, magmatism and surface uplift of the Tibetan Plateau.

The researchers point out that future research is needed to address the timing and mechanism of the uplift of the Tibetan Plateau. And the research directions include: resolving the inconsistency between the amount of Indo-Asian convergence and crust shortening, high-resolution paleelevation data, Earth system simulation, and combined geophysical and geodynamic simulations.