Study On Microstructure Characteristics Of Fault Gouge In Yangshulin Profile Of Inner Mongolia And Its Application In Fault Activity

Fault activity can not only cause earthquakes,but also induce a variety of geological disasters such as collapses,landslides and debris flows.Its destructive power is huge and its influence is long.The rapid dislocation displacement of active faults induces tectonic earthquakes and influences the distribution and development characteristics of geological disasters.Fault gouge is the direct product of fault activity,which can reveal important information of fault evolution history,such as age,nature and intensity of fault activity.The study of fault activity characteristics such as fault activity age and activity mode can provide geological basis for site selection planning of major projects,genetic types and prevention measures of geological disasters,and the relationship between active faults and earthquakes.In this paper,taking the Yangshulin profile of the Shuiquanzigou-Tianshankou fault zone in Inner Mongolia as the research object,the fault gouge samples which were collected from this profile are comprehensively studied by means of X-ray powder diffraction(XRD),laser particle size analyzer and environmental scanning electron microscope(ESEM),and then the fault activity is analyzed.The main understandings obtained are as follows:1.The XRD results of fault gouge samples show that the main minerals in fault gouge are clay mineral,quartz,plagioclase and limonite.2.The characteristics of grain size analysis of fault gouge samples indicate that the fault experienced violent movement during its development,and the fault activity mode is mainly stick-slip.3.The study of fractal dimension of fault gouge grain size shows that the fault structure is loose and in a state of no pressure or less pressure.According to the variation rule of fractal dimension between samples,the closer to footwall,the older fault gouge is formed.The farther away from the surface,the older the fault gouge is.4.Based on the identification,classification and statistical analysis of the micromorphology types of quartz particles,it is estimated that the relative time of fault activity started in the Early Pleistocene,experienced several periods of activity,and still had certain activity until the Holocene.The closer to the hanging wall,the newer the activity age;The closer to the footwall,the longer the activity.5.According to the formation age and the variation trend of active age of the fault gouge samples,it is inferred that the hanging wall of the fault is the active wall,and the development direction of the fault gouge is from footwall to hanging wall.In the process of hanging wall rising,fault gouge develops continuously.6.The fault is an active fault related to seismic activity,which is mainly stick-slip and weak creep-slip by the method of fuzzy mathematics.