Cenozoic Exhumation Rate Of Western Part Of Northern Qilian Mountains

The Qinghai-Tibet Plateau as one of the world’s youngest orogenic today, and it records the history of the India plate and Eurasian plate collision. The research about tectonic deformation of the northern Tibetan Plateau is a key to understand the remote effect of India and Eurasia collision and the process of the plateau uplift. Usingapatite fission track dating method, we study the rate of erosion on the northern margin of the Qilian Mountains. As the Qilian Mountains is located in the northern margin of the Tibetan Plateau, it response to plateau uplift sensitively,(We study the section of Huoshaogou of the Jiuxi Basin, the Ciyaokou section and the Shiyangquan section of Jiudong Basin in Northern Qilian Mountains specifically.) and collected the14Cenozoic clastic rock samples to study apatite fission track ages. The dating results showed that:The Northern Qilian Mountains uplift and erosion rapidly in44-40.3Ma; it rose gradually and erosion evidently in40.3-33.4Ma; the rate of uplift and erosion slightly and horizontal movement strengthened significantly in34.4-33.8Ma; the rate of uplift and erosion were accelerated in33.8-30.4Ma; the rate of uplift and erosion decreased slightly in30.4-23.3Ma; the rate of uplift and erosion accelerated in23.3-22.7Ma; in22.7-9Ma, the rate uplift and erosion are faster than the former period.The studies have shown that the use of low temperature’s account as detrital fission track denudation of the deposition can be qualitatively investigate the source region, the results similar to other methods’ conclusions. Combined with the results of previous studies, the dating results of the paper show that about44Ma the North Qilian Mountains, despite uplifting high frequently and erosion phase fast exist shocks or volatility characteristics,(despite uplifted frequently and erosion obiviouly, it shows the characteristics of shocks or volatility) but the overall performance are uplifting and increasingerosion rate trend.(but the overall trend was that the rate of uplifting and erosion were increasing.)...