Tectonic Deformation And Evolution Of Xiaojinhe Fault Of Muli Area

Xiaojinhe fault is the southwest section of the Longmen Mountain-Jinping Mountain-Yulong Snow Mountain in the Mesozoic and Cenozoic nappe tectonic belts.It is an important boundary between the Songpan Ganzi orogenic belt and the Yangtze platform.The tectonic evolution and deformation characteristics of the Xiaojinhe fault reflect the bi-directional orogenic polarity of the Songpan Ganzi orogenic belt,and the study of the Xiaojianghe fault structure is mostly the discussion of the seismogenic mechanism and the activity since the Quaternary.Tectonic geology studies of small tectonic patterns and combinations are ignored.In this paper,geometrical and kinematic studies on the small structures in the Xiaojinhe fault and its tectonic belts are studied by using the small tectonic analysis method to study the geologic observation of several lines crossing the Xiaojinhe fault.The following results:(1)Xiaojinhe fault of Muli area is divided into arc and Mianya section of the two sections.(1)arc section north branch fracture can be divided into Bowa Township fault,Hongke village fault,Heilaigou fault.(2)Xiaojinhe fault arc section of the main fault along the E-W direction of the general spread to the south for the arc,after Yazu Township and Hetaowan village.The Mianya section of the Xiaojinhe fault is divided into two branches,the branch 1 is NE-SW to the Mianbu village,after the Changbai Township;branch 2 NE-SW to the distribution,after Peach Township.(2)The arc section is mainly composed of breccia belt,cleavage zone,lens belt,positive fault or thrust small fault,localizedright-handed movement;the Mianya section of the main performance for the arc cleavage zone,the internal material for the particles,porphyroclasts belts,localized left-handed movement.(3)The tectonic evolution of the Xiaojinhe fault is divided into six periods:(1)The first period is the Indosinian reverse fault,the maximum principal compressive stress direction is E-W;(2)The second period is the thrust activity of Yanshanian,the maximum principal compressive stress direction is NW-SE;(3)The third period is the normal fault activity of Yanshanian,and the tensile stress direction is E-W;(4)The fourth period is the reverse fault of the Himalayan,and the maximum principal stress direction is NE-SW(5)The fifth period is the normal fault activity of early Pleistocene,and the tensile stress direction is NNW-SSW(6)The sixth period is the NW-SE thrust left-handed activity since the Middle Pleistocene.