Downcutting and uplifting in the middle part of Qinling orogenic belt during the late Quaternary

Layered cave passages formed on the walls of the Qianyou River valley in the middle part of the Qinling Mountains since the Pleistocene due to the intermittent uplifts. 12 speleothem samples near ruins of palaeowater tables in 3 cave passages are dated by using the 230Th method. The results show that the 3 caves began to uplift (358±38) ka, (247±28) ka, (118±19) ka ago respectively. Given the differences of elevation between the caves, we could obtain the downcutting rates of the valley: (0.23±0.02) mm/a during 358-247 ka, (0.19±0.03) mm/a during 247–118 ka, and (0.51(0.08) mm/a since 118 ka. This implies that more and more strong uplifting sustained in the middle part of Qinling since 358 k