New study unravels how Tibetan Plateau rose to its soaring height to become ‘roof of the world’

PTI

Beijing, February 10

The Central Tibetan Valley rose from a low valley into its current soaring height of over 4,000 metre between 38 and 29 million years ago, according to a new study, which provided fresh clues to the formation of the mountainous region—known as ‘the roof of the world’.

Surrounded by imposing mountain ranges that harbour the world’s two highest summits, Mount Everest and K2, the Tibetan Plateau is also referred to as the Qinghai–Tibet Plateau.

According to the study published by Chinese geologists on Thursday in the journal, Science Advances, the Central Tibetan Valley was at a relatively low elevation of 1,700 metre between 50 and 38 million years ago, sustaining a subtropical “Shangri-La” diverse ecosystem.

It rose rapidly to become a part of what is now the Qinghai-Tibet Plateau, at an elevation over 4,000-metre between 38 and 29 million years ago, the state-run Xinhua news agency reported, quoting the study.

Chinese and British scientists led by Ding Lin from the Institute of Tibetan Plateau Research under the Chinese Academy of Sciences collected a large number of samples from the Lunpola Basin within the centre of the Valley for radiometric dating and clumped isotope analysis.

They found nine layers of volcanic tuffs there, and established the absolute age framework across ancient sediments in the basin, thus revealing the exact point of geological transition.

The study showed along with the elevation and the cooling of the global climate, the temperature and precipitation in the central plateau decreased significantly.

Thereafter, climate change transformed the place from one that hosted a warm-humid, low-elevation subtropical ecosystem serving as an incubator for today’s exceptional Asian biodiversity, to a high, cold-dry alpine ecosystem.

Further, the team proposed a new model of Qinghai-Tibet Plateau formation, in which the subducting Lhasa (provincial capital of Tibet) mantle fell away and/or was thermally eroded, allowing the upwelling of the asthenosphere, a thin semifluid layer of the earth.

This process softened the crust above and facilitated the northward movement of India, finally giving rise to multiple high mountains including the Himalayas, the study added.