EVOLUTION OF THE QINLING OROGENIC BELT

Detailed field mapping, geophysics, and geochemistry show that the Qinling orogenic belt is a southward vergent tectonic wedge consisting of six regional thrust sheets (the Lushan, Luanchun, Qinling, Douling, Wudang, and Zhuqi thrust sheets). These regional thrusts underwent displacement at the end of the mid-Triassic and the end of the late Jurassic due to the collision between the North and South China blocks and subsequent detachment. The Qinling orogenic belt is thus an Indosinian-Yanshanian collision-detachment zone. The so-called "Caledonian orogeny" in the Qinling Orogenic Belt records a succession of extensional and partial melting events in the continental crust. The basic lavas in the lower Paleozoic were erupted into rifting zones (both in the northern Qinling subzone and southern Qinling subzone). At the same time, local melting of the transitional continental crust occurred and resulted in formation of S-type granites.