Apatite fission track constraint on thrust faults in Kangtuo Basin, north-ern Tibet

Four rock samples collected from the Kangtuo Basin in northern Tibetan Plateau were used to determine the apatite fission track ages. Results of all the samples show that the individual grains belong to a single population with a single mean age and have central ages of 77±6Ma, 62±5Ma, 44±3Ma and 35±2Ma. Their mean track lengths are 11.6±2.0～13.3±1.9μm with a single peak. The authors used thermal history simulation software AFTSolve to simulate the thermal history of the samples and the results show three important stages of tectonic movement in Kangtuo Basin since Late Mesozoic. From 100Ma to 65Ma, the cooling and denuda-tion rates were 1.46～4.26℃/Ma and 0.05～0.14mm/a respectively. Combined with field condition and study results, some conclu-sions have been reached:The Cretaceous tectonic uplift event was influenced by the subduction of the Yarlung Zangbo River. The second tectonic movement took place between 50Ma and 35Ma and its intensity was weaker than that of the first one. The Paleogene tectonic uplift event was related to Indo-Eurasian collision. Since 20Ma, the cooling and denudation rates have been 3.25～6.0℃/Ma and 0.03～0.2mm/a respectively, and this tectonic movement has been influenced by the Cenozoic whole uplifting and the stretching strike-slip environment in Tibet.