CAS experts: no more increase in the height of the Tibetan Plateau

Translated from www.xinhuanet.com

“When the plateau has reached a certain height, it can only expand to the two sides and grow in spatial coverage under giant platonic pressure.” Prof. Ding Lin, researcher of CAS, recently told reporters. In answer to the popular predictions that the Tibetan Plateau is still growing in height, Prof. Ding believed that the Tibetan Plateau today has come to its collapsing stage after it reached its acne. He drew this conclusion from the light granite discovered in high elevated regions in Mt Himalayas in the recent years. As is known that such light granite, which was the product of mid- and under- crustal melting, forms at 2500-3000m underground. Accompanied by its formation, crust shortens its large-scale thickening process. Besides, scientists also noticed a series of anti-crustal break east west wardly in Cuoqin county, Ali region of Tibet. From its cross section, they could tell a 60% shortening of crust before the collision between the Indian plate and the Euro-Asian Plate. Similar phenomena are also believed to be widely present in other areas on the plateau.

Areas of higher elevation on the plateau are believed to witness such crustal shortening in large scale and the consequent uplifting of mountains far before the cretaceous period. He added. In the light of various scientific discoveries, the average altitude of the Tibetan Plateau may be 5500m above sea level 23 million years ago, and that should be the ultimate height for the plateau before collapse; while now the average elevation of the plateau is ca. 5023m.

 Studies show that 65million-50 million years ago, the collision between the Indian plate and the Euro-Asian plate was followed by a series of sharp processes as compress, uplifting and wide expansion on the Tibetan Plateau. A number of south-north ward rift valley on the plateau showed that since the Miocene Epoch, the plateau was not only expanding and uplifting, but also showing a large-scale expansion in Mt Gangdis and the Himalaya region. Now there are eight giant rift valleys on the plateau cutting the east-west-wardly mountains such as Mt Tanggula, Mt. Gangdis and Mt. Himalayas. The different widths of the valley ranging from 35 km in its widest part and 5 km in its narrowest are sound proofs for the crustal expansion, esp. shown in lava, hydro-heat, mineral liquid and Pleistocene volcano rock found in many valleys on Mt Gangdis and Mt Himalaya.

All the current phenomena confirmed that the Tibetan Plateau is changing from earlier compressing to latter expansion and deformation. Said Prof. Ding Lin, confirmed by the scientific analysis that having been active for 23 million years, these rift valleys have turned to rapid expanding in the past 13 million years, and they are still doing so. In Prof. Ding’s eye, the current situation on the Tibetan Plateau was quite similar with basin regions in West America. It is at a collapsing phase, about to change from plateau to the basins. Admitting the fact that some mountains, under compression, are still growing slightly, Prof. Ding concluded that under gravitation, the Tibetan Plateau as a whole will grow no higher, but expand in spatial coverage and decrease in height.