Abstract:

 As the boundary between the north Huaiyang unit and the North Dabie complex unit, the XiaotianMozitan fault is a very important exhumation channel Based on the detailed field survey, the estimation of temperature and pressure during the mylonitization, and the measurement of quartz Caxis fabrics, we calculate the kinematic vorticity numbers and strain rate during the synorogen mylonitization of the XiaotianMozitan fault The mylonites formed in the depth of 3040 km as indicated by the temperature and pressure of the deformation, which is more than the amount of denudation since the Cretaceous and suggests that the mylonitization was formed in the exhumation of the Dabie orogenic belts The kinematic vorticities are all more than 09, which indicates that the deformation was mainly the simple shear The XiaotianMozitan fault is a fault with shear sense of toptotheNW as shown by microstructures and quartz Caxis fabrics The strain rate of the synorogen mylonitization is about 10-10  s-1, which suggests that the exhumation rate is very high after the peak metamorphism in the Dabie orogenic belts

Key words:

Key words: the XiaotianMozitan fault; synorogen mylonitization; kinematic vorticity; strain rate; exhumation of UHP rocks