裂变径迹热年代学对西藏卓奥友峰藏南拆离系活动时间的约束

引入裂变径迹方法研究藏南拆离系(STDS)的活动历史。通过青藏高原喜马拉雅卓奥友峰5个锆石和4个磷灰石样品的裂变径迹实验，分别获得11.2~17.1 Ma和12.4~14.3 Ma的年龄范围。年龄温度法计算得到中新世时期洛子峰拆离断层在卓奥友峰地区剥蚀作用逐渐增强的结论：(1)17.1~15.2 Ma地壳冷却速率较慢，约为37.8 ℃/Ma；(2)15.2~13.5 Ma地壳冷却速率为82.4 ℃/Ma，并且在14.3 Ma左右构造活动最强烈，达到峰值；(3)13.5~12.4 Ma地壳冷却速率可达100 ℃/Ma。

The constraints of the fission track thermochronology on active time of the Southern Tibetan Detachment System in Cho Oyu,Tibet.

This research uses fission track experiments to study the geological activity of the South Tibetan Detachment System (STDS) based on 5 zircon samples and 4 apatite samples from the Cho Oyu in the Tibetan Himalayan. The age range of the zircons is 11.217.1 Ma and that of the apatites is 12.414.3 Ma. After integrating the age closure temperatures measured for these samples, we found that the crustal cooling rate of the Lhotse detachment fault along the Cho Oyu increased gradually during the Miocene：(1) during 17.115.2 Ma the crustal cooling rate was approximately 37.8 ℃/Ma; (2) during 15.213.5 Ma the average crustal cooling rate was ~82.4 ℃/Ma, and the tectonic activity was most intense at ~14.3 Ma; (3) during 13.512.4 Ma the crust cooling rate during that time was up to 100 ℃/Ma.