The apatite fission track analyses have been performed for total 4 samples collected from upper Permian System sandstone in South-Block of eastern Kunlun Mountains. The ages range from (48±3) Ma to (89±8) Ma
in accord with regional thrusting time
and the confined track lengths are from (10.7±2.3) μm to (10.8±2.2) μm with a single peak value
showing that the samples kept a long time at the annealing zone of apatite fission track and then uplifted rapidly. Three tectonic phases have been revealed in the whole. A comparative cooling occurred from ~107 Ma to ~80 Ma first
following a quiet phase and then a rapid cooling started at 6—12 Ma until now with a cooling speed of 5.3—9.8 ℃/Ma or 106—196 m/Ma.