Ductile shearing in the eastern segment of Central Kunlun tectonic belt and its geological significance

Multi-stage structural events occurred in central East Kunlun tectonic belt, resulting in complex structural styles which have been preserved up till now．Very intense structural deformation and ductile shear zone exist in Hatugou, Qingshuiquan-Tatuo and Gouli areas, and there is the NWW-SEE ductile shear zone．The authors analyzed the geometry, kinematics and kinetics of the tectonic belt based on field investigation and analysis of microstructure. A quartz C-axis petrofabric analysis on Fedorov and EBSD stage indicates that the shear zone is a pressure- shear structure interface, characterized by left- handed thrust at the early stage, dextral strike- slip at the late stage, and 400~550 ℃ for the deformation temperature．The measurements of sub-grains of quartz and granularity of dynamic recrystallization indicate that the paleostress value is 153.79 MPa for the ductile shear zone in the study area. Furthermore, the closer to the central part of East Kunlun tectonic belt, the higher the Flinn index (>1), the extent of the strain and Lode parameter (absolute value) of gravel, as evidenced by the finite strain measurement of conglomerate (4 points) from Maoniushan Formation in Hatugou, which suggests a tensile deformation. Combined with regional geological data, the authors hold that the eastern segment of central Kunlun ductile shear zone was formed in Late Hercynian and Indosinian.