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  

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

作　　者：高成[1,2] 刘娇[1] 李德威[1,3] 汪帆[1] 刘德民[1] 

机构地区：[1]中国地质大学(武汉)地球科学学院,湖北武汉430074 [2]中国地质大学(武汉)地质调查研究院,湖北武汉430074 [3]中国地质大学(武汉)青藏高原研究中心,湖北武汉430074

出　　处：《地学前缘》2014年第6期372-380,共9页Earth Science Frontiers

基　　金：中国地质调查局区域地质调查项目(1212011121242;1212011121246);国家自然科学基金项目(41172188)

摘　　要：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11.2-17.1Ma和12.4-14.3Ma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）17.1-15.2Ma地壳冷却速率较慢,约为37.8℃/Ma;（2）15.2-13.5Ma地壳冷却速率为82.4℃/Ma,并且在14.3Ma左右构造活动最强烈,达到峰值;（3）13.5-12.4Ma地壳冷却速率可达100℃/Ma。This research uses fission track experiments to study the geological activity of the South Tibetan Detachment System（STDS）based on 5zircon samples and 4apatite samples from the Cho Oyu in the Tibetan Himalayan.The age range of the zircons is 11.2-17.1 Ma and that of the apatites is 12.4-14.3 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 17.1-15.2Ma the crustal cooling rate was approximately 37.8℃/Ma;（2）during 15.2-13.5Ma the average crustal cooling rate was-82.4℃/Ma,and the tectonic activity was most intense at-14.3Ma;（3）during 13.5-12.4Ma the crust cooling rate during that time was up to 100℃/Ma.

关 键 词：淡色花岗岩 裂变径迹测年(FT) 藏南拆离系(STDS) 卓奥友峰 青藏高原 

分 类 号：P542[天文地球—构造地质学]