Study On Structural Deformation Characteristics Of Northern Part Of Ductile Shear Zone In The Area Of Xingcheng-Taili,Western Liaoning

The Xingcheng-Taili ductile shear zone of western Liaoning is located to the east of the northern margin of the North China Craton.It is of NE-SW trending,with a length of about 6km and a width of about 1²km.The macro and micro structures in the northern segment of Taili shear zone are analyzed combined with the analysis of rock deformation strength difference,the measurement of finite strain,the estimation of kinematic vorticity,the analysis of quartz C-axis EBSD fabric and the estimation of paleo-stress values and strain rates.The results reveal that the granitic rocks in shear zone have undergone intense ductile deformation,so deformation fabrics occurred,such as mylonitic foliation,stretching lineation,S-C fabric,augen structure and domino structure.Various types of kinematic markers indicate that the shear zone has the characteristics of NNE-trending sinistral shear deformation,with deformed rocks of S-L tectonite and strain type of plane strain.The kinematic vorticity W_k value is greater than0.75,indicating it is formed by the general shearing that is dominated by simple shearing.The mineralogical thermometer of feldspar-quartz and the EBSD fabric of quartz C-axis indicate that medium and low temperature deformation mainly occurs in the shear zone,which belongs to the deformation of greenschist facies,with a temperature of 400?-500?and paleo-differential stress of between 30⁴0MPa.The strain rate is low,ranging between3.43*10^-163.98*10^-13s^-1for low temperature deformation and 7.14*10^-141.14*10^-11s^-1 for high temperature deformation.Deformation partitioning is common in the ductile shear zone.The ductile shear zone in Xingcheng-Taili area is formed in mid-shallow crust in Early Cretaceous.Its formation is related to the extension and thinning of the North China Craton resulting from the subduction and retreat of Izanagi plate to Eurasian continent.