Apatite fission track evidence for the Miocene rapid uplift of the Qimantag Mountains on the northwestern margin of the Qinghai-Tibet Plateau

Fission track analysis was performed on nine apatite samples from different altitudes of the Qimantag Mountain. The results show that: the main uplift period in the western segment of the East Kunlun Mountains was early-middle Miocene, when the uplift rate was relatively high, with an uplift rate of 111 m/Ma in the early stage and an uplift rate of 98 m/Ma in the late stage and a general uplift rate of 100 m/Ma. Sample analysis indicates that according to the fission track lengths, apatite may be divided into two types. One type of apatite has fission track lengths of 12.21±0.20 to 13.75±0.30 μm, and its fission track lengths are in the main of narrow and symmetric normal distribution, which reflects that this type had a rapid denudation and cooling rate and was not subjected to interference of the late-stage thermal event. The other type of apatite has fission track lengths of 11.88±0.33 to 13.32±0.27 μm, suggesting that this type had a denudation and cooling rate slightly slower than the former type and underwent the interference of the late-stage thermal event.