China News Service, Beijing, June 28th (Reporter Sun Zifa) What did the Tibetan Plateau look like 44 million years ago? What are the major environmental changes?
Academician Ding Lin and other researchers from the Institute of Tibetan Plateau Research of the Chinese Academy of Sciences found that: 44 million years ago, due to the northward subduction of the Indian mainland, the Gongjue Basin in the southeast of the Tibetan Plateau was formed by a desert at 700 meters above sea level. Uplifted into a forest at an altitude of 3800 meters.
Researchers collected carbonate nodules in the sedimentary layers of rivers in the Gongjue Basin and used them for paleo-altimeter and paleo-thermometer testing. Photo courtesy of the research team of the Institute of Tibetan Plateau, Chinese Academy of Sciences
The Qinghai-Tibet Plateau Institute of the Chinese Academy of Sciences announced on the 28th that the academician Ding Lin team and the Chinese-foreign cooperative unit jointly completed this prehistoric major environmental change study of the Qinghai-Tibet Plateau, and the results of the paper have recently been published in the international authoritative geosciences journal Earth and Planetary Science News.
This study is the first to use multiple quantitative indicators to reconstruct the uplift history of the eastern segment of the Qinghai-Tibet Plateau’s watershed, revealing the major environmental transitions from low-altitude deserts to high-altitude forests in the southeastern Tibetan Plateau, and to discuss the uplift of the Tibetan Plateau for Asian seasonal styles and regions The driving role of environmental type evolution.
The paleogeographic pattern evolved between 55-50 million years and 44-40 million years on the Qinghai-Tibet Plateau. (Comprehensive research team data and refer to Ding et al., 2014; Valdes et al., 2019) Photo courtesy of the research team of the Institute of Tibetan Plateau, Chinese Academy of Sciences
The first author of the thesis, Xiong Zhongyu, a doctoral student of the Institute of Tibetan Plateau of the Chinese Academy of Sciences, said that the watershed mountains of the Tibetan Plateau lie in the middle of the Tibetan Plateau, and include Hengduan Mountains, Tanggula Mountains and Karakorum Mountains from east to west. They are the Pacific and Indian Ocean systems. The watershed is also the "backbone" of the roof of the world. Its formation and uplift have an important impact on the paleoenvironmental pattern of the Qinghai-Tibet Plateau and even the entire East Asia. Previously, there was a lack of detailed research on the uplift of the watershed mountains from low to high.
The Gongjue Basin is located in the northern part of Hengduan Mountains and is an ideal area to study the uplift history of the watershed mountains in the Qinghai-Tibet Plateau. In 2016 and 2018, the research team of the Institute of Tibetan Plateau Research of the Chinese Academy of Sciences went to the north of Gongjue County, Changdu City, Tibet Autonomous Region twice to conduct a field surgery test on the Gongjue Basin, and found two sets of very different sedimentary strata: the lower stratum was deposited with sand and rivers. Mainly, formed in a relatively arid environment; the upper strata are mainly lake sediments, formed in a relatively humid environment. The research team also found palm plant leaf fossils in the fine sandstone deposited by the river, indicating that the temperature in the basin was relatively high.
The research team used the oxygen isotope paleo-altimeter and carbonate ancient thermometer, combined with palm plant fossils, high-precision volcanic rock chronology, climate simulation and previous research results to find that 54 million years ago, the southeastern Tibet represented by the Gongjue Basin was still A lowland area, mainly controlled by the westerly belt, the climate is hot and dry, with an average annual temperature of up to about 24 degrees Celsius, forming a large area of desert, with subtropical flora.
Academician Ding Lin, the corresponding author of the paper, pointed out that by 44 million years ago, due to the northward subduction of the Indian mainland, the Gongjue Basin rose to 3,800 meters, and the southeastern Tibet quickly rose to an altitude similar to that of today. He believes that with the elevation of the terrain, the monsoon began to play a leading role in southeast Tibet, the climate became relatively humid and cool, and the average annual temperature dropped to about 7 degrees Celsius. At the same time, the types of vegetation have also changed, and alpine forests have begun to appear, which is close to the current environmental types in southeastern Tibet. (Finish)