GUO Shangyu¹, WU Xiangke¹, ZHAO Bing¹, LI Dan²

I [Objective] In order to understand the deformation characteristics of Yunkai area, [Methods] this paper focus on the Shili ductile shear zone on the northwestern margin of Yunkai Block. Based on the methods of field geological survey, the finite strain measurement, the kinematic vorticity Analysis and ⁴⁰Ar-³⁹Ar geochronology. [Results] The generally NWW—SEE trending Shili ductile shear zone indicates top-to-NW thrusting, it shows progressive deformation from ductile shear deformation, brittle-ductile deformation to fold deformation. In the mylonite formed during the ductile shear deformation, ⁴⁰Ar-³⁹Ar plateau age of muscovite is 232±2.3 Ma（MSWD=3.65）, the Flinn parameter(K) is 0.06~0.77, the lod parameter (υ) is 0.13~0.89, the strain intensities(Es) is 0.41~0.51, the kinematic vorticity values(Wk) is 0.70~0.78. [Conclusion] This study reveals that the Shili ductile shear zone formed due to far-field stress propagation from the NE-SW collision between South China and Indochina.