Recently Nature Geoscience published the paper centering on the formation time and driving mechanism of Lancang River which was wrote by Nie Junsheng goup, from The Key Laboratory of Western Environment of School of Resources and Environment, LZU. The paper was named "Rapid incision of the Mekong River in the middle Miocene linked to monsoonal precipitation".
Lancang River, as one of the top ten rivers in the world, originates from Qinghai Province, flows through dozens of countries in southeastern Asia, including Laos, Myanmar, Thailand, Cambodia and Vietnam, etc., and flows into South China Sea through Ho Chi Minh of Vietnam, providing important guarantee of food, water and income for China and the countries in southeast Asia. Understanding the formation and evolution of Lancang River is an important scientific issue and is of great social significance. However, the existing research group held that Lancang River was formed at least 500 millions years ago while another group thought it was formed less than 5 millions years ago based on different evidence. They were largely divided.
The formation of rivers tends to be accompanied by streamway down-cutting, so the formation time of valley of Lancang River can provide the correct answer properly. However, it is difficult to effectively measure the formation time of the valley. Nie Junsheng, Hu Xiaofei, Wang Zhao, Liu Shanpin from LZU and their cooperators, overcame lots of difficulties and eventually collected samples form different valley section, thereby making sure the valley’s streamway down-cutting time by thermochronology. They found that valleys in upstream, midstream and downstream of Lancang River went through strong and fast streamway down-cutting around 17 millions, which led to the occurance of Lancang River. At the same time they also found that the valley’s streamway down-cutting time was consistent with the time when east Asian monsoon intensified. Later they conducted a simulation experiment to see whether the intensification of monsoon could led to the fast streamway down-cutting as they observed. The result showed that the increase of rain made by the intensification of east Asian monsoon could result in the fast streamway down-cutting and formation of Lancang River, confirming that climate change is an important reason for the formation of Lancang River.
The news link of Nature’s report :
The link of the paper:
(Translated by Sun Lianyue; Proofread by Yang Han; Edited by Zhang Yuyuan)