ARCUATE THRUST NAPPE STRUCTURE ON THE SOUTHERN MARGIN OF THE SOUTHERN QILIAN MOUNTAINS

The arcuate thrust nappe structure on the southern margin of the southern Qilian Mountains is a nappe system with a double overlapping structure. Its autochthonous system consists dominantly of Jurassic Cretaceous coal measures and molasse formation, while its allochthonous system is composed of the Proterozoic, Paleozoic and Triassic. The general slip direction of the nappe is from north to south （SSW）, with a maximum slip distance of over 10 km. The nappe structure was formed in the late Yanshanian stage by the combination of the basin extension occurring under the effect of the mantle diapirism and the intraplates stress produced due to the collision with the Tethys terrane.