The Geology Characteristic And Structural Simulated Experiment Of Qingping Klippen In The Middle Segment Of Longmen Mountain Tectonic Belt

Longmen Mountain tectonic belt is located in the northwestern margin of the Sichuan Basin and also it is an important tectonic belt in southwestern tectonic belt of China. From it,s northwest to southeast,there are four main faults which we called Maoxian-Wenchuan fault, Yingxiu-Beichuan fault, Pengguan-Anxian fault,Guangyuan-Dayi fault. Qingping Klippen area that we studied is located in the middle of Longmen Mountain tectonic belt,a large overlapping klippen in the easten of Yingxiu –Beichuan fault. author according to the surface geology investigation in the area of Qingping Klippen area and the indoor structural simulated experiment,Combining with the evolution of the regional tectonic dynamics,to explore the mechanism of its formation.Qingping klippen is a large overlapping klippen,From the lower(South) to the upper(North) divided into : Longwangmiao-Baiyunshan klippen;Yanjinggou-Dingziya klippen;Huabangou-Yuantoushan klippen;Yaneryan-Jingsigou klippen; Erlangmiao klippen. Plane distribution, each secondary klippens is surrounded by the fault,and the fault present ?U?. The two underlying secondary klippens(south)have Large area,The tectonic line is near to the NS,Leading edge fault point to the Southwest;the other three overlying secondary klippens(north)have little area,present Strip type,The front fault is roughly parallel to a NE-SW. present each secondary klippens sliding surface is not harmonious. Section,The two underlying secondary klippens present positive- inverse sliding block type,Internal formation relationship is complex,Tectonic deformation severe,and From trailing edge to leading edge become stronger gradually,The leading edge of the klippen is the extrusion fold. The other three overlying secondary klippens are all be cut off by thrust sheet(or thrusting fault),overlapped with each other,slip surface fault parallel to the Yingxiu-Beichuan fault,Internal formation is relatively simple,Tectonic deformation Relatively weak.The structural simulated experiment is a very effective means of research in the structural geology. It,s essence is the geometric deformation method, by using a variety of analog materials,design reasonable boundary conditions and loading an external power to simulate the tectonic dynamic background,Representation of the formation process and its evolution of the tectonic styles, and to explore the mechanism of its dynamics. Based on the results of previous studies on Qingping Klippen,and the harvest of field geological survey, two different power sources structural simulated experiment have been designed:(1) vertical uplift-Gravity sliding structure;(2) uniaxial way squeeze-Gravity extension sliding structure. The results show that: The two underlying secondary klippens(south)were high similarity with the vertical uplift-Gravity sliding structure;the other three overlying secondary klippens(north)were high similarity with the uniaxial way squeeze-Gravity extension sliding structure.The Structural dynamics genetic mechanism of Qingping Klippen is closely related to the tectonic evolution of the entire Longmen Mountain tectonic belt. By summarizes the results of previous studies on Qingping Klippen,according to the surface geology investigation in the area of Qingping Klippen area and the indoor structural simulated experiment, Combining with the evolution of the regional tectonic dynamics,we infer that the superimposition klippen in Qingping were first formed by Gravity sliding in the previous normal faultings, detachment fault is the unconformity between proterozoic and ediacaran. And take place Gravity extension sliding in the thick deyonian which was the main Regional detachment layer.Then it goes through differential uplifting stage and continuous uplifting- Gravity sliding corerage stage in the late Indosinian, the thrust nappe- Gravity extension sliding corerage stage in the Himalayan period. And the later weathering and erosion has finally formed the klippen. The two underlying secondary klippens were formed in the stage of Gravity sliding corerage stage,the other three overlying secondary klippens were formed in the Gravity extension sliding corerage stage.