| Emeishan is located in the southwest of Sichuan basin and the west margin of Yangtze paraplatform which is across the Yangtze fold belt of the emeishan broken arch and the west platform subside of Sichuan depression. It contains Ebian dome break beam, Yaan concave fold beam and Chengdu broken concave. There are beautiful scenery and complex geological features in this area. The magmatic activity, emeishan taphrogenic movement and several multiphase tectonic movements formed the various types of fault and fold. It attracted many geologists to study it and achieved remarkable geological results, but it lack of three-dimensional geological model as the practice teaching area of Chengdu university of Technology. In the article certain achievements was obtained by the field geological investigation in the emeishan practice teaching, combining previous data, using Gocad software for 3D modeling and making structural interpretation of the model.The advantages of the Gocad software are using the DIS method for interpolation calculation, free to choose, changing the grid model automatically and real-time interactive operation. According to a series of the space coordinates and the physical properties of the interconnected nodes and making the anisotropy of data as value of the constraint conditions it can create smooth surface and build a better geological model. The modeling steps are simple and clear. The structure modeling workflow has ten steps: Data Managing,Volume of interest, Fault Modeling,Horizon Modeling,Fault well markers fitting,Fault Contact Modeling,Horizon-fault Contact Modeling,Horizon well markers fitting,Remove Horizon Crossing and Isochore Modeling.Due to the complexity of geological structure and lacking of earthquake, geophysical data, we use the geological map, geological section, attitude of stratum to speculate the geological body and the deep extension of geological structure. The 3D geological modeling in emeishan practice teaching area was completed by collating data and determining the tectonic framework of the study area, in accordance with the inflection point and the geological structure features of the study area to generate the workspace and geological surface, editing the contact relationship between the various geological surfaces, loading data to generate the model and modifying the model properties and loading the text.The Gocad three-dimensional modeling software which provides a variety of methods that incloud Z-Scaling, rotate,exploded view,lid-take-off,Slicer,Calculate the volume and area,projection,Dynamic cutting section.Those methods were used to interpretate the geological phenomenon and analyze the evolution process of the structure characteristics of each blocks in the study area. In the Proterozoic, the area was at the development stage of geosyncline. It gives priority to with Ferry,s tectonic and second develops carbonate and volcanic rock tectonics. The Geosynclinal fold return and Emeishan granite intrusion formed the fold basement of this area in the late Proterozoic of early Sinian Period. The tectonic movement from Sinian period to the Paleogene was main performance for many times of lifting activity. It has corresponded to the multiple parallel unconformity surface between the strata. In Paleogene, the India plate has moved to the north and collided with Eurasia plate. The Qinghai-tibet plateau was lifted and compressed by the stress of north-south which caused deep material lateral escape and eastward extrusion. The study area was affected by the east-west principal stress, the formation has folded and fractured and formed a series of fold and fault of north and south, north west and north east. In Neogene, the study area has inherited the previous tectonic pattern. The Emeishan area was whole uplifted and the Miocene sediments was missed. In the Quaternary, the area was affected by the western regional tectonic stress, the tectonic movement has further developed and formed the tectonic framework of now. |
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