Studies have shown that tectonic activity and deformation in the Pamirs began in the Cretaceous

The Pamirs are located in southeastern Central Asia, the westernmost tip of China, straddling Tajikistan, China and Afghanistan.

One of the landform types of the Pamir Plateau in the Xinjiang region. Photo by Zhang Xingyong

The research team of the Institute of Earth Environment of the Chinese Academy of Sciences conducted geomorphological investigation and sample collection of modern river sediments in the field. Photo by Zhang Xingyong

The Pamir arc-shaped tectonic belt is located at the northwest edge of the Qinghai-Tibet Plateau, and is controlled by the long-range effect of collision between the Indian plate and Eurasia since the Cenozoic era, resulting in a strong north-south shortening of the earth’s crust, resulting in a sharp contrast between its width and the Qinghai-Tibet Plateau on the eastern side.

“The simultaneous uplift and thickening of the Pamir arc tectonic belt, the different sliding rates of the strike-slip faults on the east and west sides, and the current geomorphology raise the question of which geomorphological processes respond to the crust shortening and deformation characteristics of the Pamir arc tectonic belt?” Chang Hong, a researcher at the Institute of Earth Environment, Chinese Academy of Sciences, believes that “the formation and geomorphological evolution of the Pamir arc tectonic belt and its relationship with the uplift of the Qinghai-Tibet Plateau are scientific questions that need to be answered urgently.” ”

Recently, Chang Hong and his team revealed the geomorphological development characteristics and influencing factors, source changes, tectonic deformation and geomorphological response process of the Yarkand River Basin in the eastern margin of the Pamir Plateau through indoor geomorphological extraction, field geomorphological investigation and sample collection and analysis of modern river sediments.

The results show that: (1) 27000 is the stable threshold for extracting the elevation integral of the Yarkand River mountain area, and the whole Yarkand River basin is in the prime of geomorphological development, which is the result of the combination of tectonic, lithological and climatic factors, among which the multi-year average annual temperature is the main controlling factor of climate on geomorphological development. (2) Pamir’s tectonic activity and deformation began in the Cretaceous period (referring to the formation of strata in the period between 145 million and 66 million years ago); (3) the evolution of the Pamir Lands is related to the growth of the Qinghai-Tibet Plateau; (4) The sediment source at the eastern edge of the Pamir arc tectonic belt changed significantly to the north; (5) The modern river pattern at the eastern edge of the Pamir arc tectonic zone is controlled by the activity of the Gonger extension system.

Clastic zircon U-Pb age maps of the Pamir and Tibetan plateau massifs. Photo courtesy of the author of the paper

The above related results have been published in Palaeogeography, Palaeoclimatology, Palaeoecology, Quaternary Studies, and Journal of Earth Environment.

The research was jointly funded by the Strategic Pilot Project of the Chinese Academy of Sciences (XDB40010100) and the Second Qinghai-Tibet Plateau Scientific Expedition Special Project (2019QZKK0707). (Source: China Science News, Zhang Xingyong, Yan Tao)

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