T242 Interrelationship between Tectonic Uplift and Quaternary Glaciations on the Tibetan Plateau and Its Surrounding Mountains

Tuesday, 24 October 2017
1:30 PM - 5:30 PM
Chelan 2

TECTONIC UPLIFT AND GLACIAL HISTORY OF MIN SHAN SINCE LATE STAGE OF MIDDLE PLEISTOCENE

Paper number: T242-14
Program: Technical Sessions
Time: 4:45 PM – 5:05 PM

Authors

Abstract

At the source of the Minjiang named Gonggaling, the former Minjiang gravel layer, which has a thickness of 300 m or more on the north and west sides of the river. At the modern watershed, the highest flow out points are Doujidongtai of 3970 m and doujitai of 3830 m. This ancient Minjiang gravel layer along the source of the current white water river has been piling up to the west bank of the Gesaerwang camp valley mouth. The expression is high terrace, about 100 m above the valley, far from the Doujitai to up to 8 km. we obtain the age of the gravel layer of this ancient Minjiang at Doujitai is 376 ka by ESR dating. The same gravel layer (T5) in the east side of Minjiang named Chuanzi Valley, was measured 388 to 400 ka at the height of 3200 m. The same terrace (T5) can be extended to the south gate of songpan, the mouth of the Mouni Valley.

The gravel layer of the ancient Minjiang terrace has been raised up to 800-1000 m in the Doujitai and Doujidongtai. There has cirques, U shaped valleys and glacial moraine lakes formed during the last glacial cycle, and the mountain height reaches 4500-4700 m in the east part. The western flank of the same section has the height lower than 4200-4300 m, with only insignificant remains of the last glacial cycle. It is seen that this rise is mainly in the middle of Minshan, which is called the Minshan movement, which occured at about 400 ka age.

According to many studies, the modern ground uplift rate of Minshan ranges from 1 to 2.5mm/a, and the local fastest location can reach 6mm/a. In this paper, 2.5mm/a is adopted to raise the average lift rate of Minshan movement. The uplifting of the Minshan from 400 ka in this area of the last glacial cycle lead to glaciers widely development, followed with the snowline raise, and mountain uplift can not meet the corresponding rate, so the modern glacier development is limited, such as Hongxingyan with the height of 5009 m, only developed last glacial cycle without modern glaciers, and the same can be found among the similar height mountains of the east of Hengdushan. The authors believe that, without considering climate change, mountain uplift is the main cause of the development of the last glacial cycle in Minshan.

Geological Society of America Abstracts with Programs. Vol. 49, No. 6

doi: 10.1130/abs/2017AM-300448

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