Study On Active Fault In Batang In Region Western Sichuan And Three-dimensional Geological Modeling

Batang area in western Sichuan belongs to Garze Tibetan Autonomous Prefecture and is located in the middle part of Jinshajiang fault zone,where the Batang fault slanting across the middle part of Jinshajiang fault zone.The study area covers Batang County surrounded by Mountains.Maqu River runs through the whole territory.It is regionally affected by the Garzi-Litang tectonic belt,with complex geological structures,strong neotectonic activities and frequent historical earthquakes.There are a lot of fault geological data and research achievements in Batang and its adjacent areas,but most of them are two-dimensional geological maps and written data while the three-dimensional data,such as satellite images,mainly reflect the surface topography,topography and spatial form.There is a lack of 3D visualization data on the distribution of geological structures such as underground strata and faults in Batang area.This paper collects and sorts out the geological data of the study area and the previous research results in the early stage,and combines the drilling,geophysical exploration and field geological survey on the research site.Based on the professional geological modeling and analysis software Gocad,in the absence of large-scale deep drilling,exploration Wells and seismic data,the section control method is used to conduct three-dimensional visualization modeling of the strata distribution and fracture structure morphology under the surface of the study area.The following conclusions are drawn.(1)The Batang fault in the area can be divided into three segments,north,middle and south,which show the characteristics of dextral distribution.There are 700-800 m wide step blocks between each segment.(2)Based on various exploration methods,the Batang fault shows obviously different fault properties between adjacent exploration points,sometimes with thrust component,sometimes with normal fault forming graben.It is considered that the Batang fault is a Holocene strike-slip fault.During the deformation process,the surface of the Batang fault is usually dominated by flower-like structures,and the fault properties of different parts may be completely different or even opposite.Therefore,the deformation mode of Batang fault can be regarded as the characteristic of pivot fault.(3)The 3D model established in Gocad software can be used for the analysis and calculation of plastids in various places in a stereoscopic and intuitive way.The display functions of grid body and entity are not available in 2D geological data,which reflects the superiority of Gocad software for structural modeling.(4)By studying the process of establishing the three-dimensional geological model,summarized a set of using graph cut section and plane geological map building complete technological process and method of 3D model in the absence of a wide range of deep Wells,drilling and seismic data.It provides a new angle of view for geological mapping,geological interpretation and geological teaching.