Application Of Multi-Source Remote Sensing Data In Studies Of Faults In Yangla Copper Mining Area,Yunnan

Yangla copper mining district is located in the juncture of Guizhou, Sichuan and Xizang Provinces with a total area of about28km2. Tectonically, the district lies in the Jinshanjian suture zone which is clamped between the Ancient Asia and Tethyan tectonic domain between the Indian plate and the Eurasian plate. Fault structures are well developed in the district. The faults are closely associated with copper mineralization. Meanwhile, the faults cut, dislocate and destruct the orebodies, increasing the difficulty in exploration. During the past geological surveys, only a few faults were recognized, due to the high elevation, complex terrain and heavy vegetation cover in the district.In this paper, multi-platform remote sensing data analysis combined with field study, is carried out to map and analyze the faults in Yangla district. Major methods used are listed as follows:(1)Several types of remote sensing data, including ETM+, SPOT and DEM (digital elevation model) data, have been used to recognize and interpret faults. The3D characteristics of the Google Earth topographic maps are utilized to identify topographic features and faults.(2) High spatial resolution satellite data (GeoEye-1data, spatial resolution0.5m at best) are used to identify micro topography and land features which are useful to identify faults. GeoEye-1images can be directly used to examine the vegetation growth density in the study area, in order to infer possible faults accurately. These data are especially useful in areas of a thick soil cover with dense vegetation..(3) The temperature vegetation drought index (TVDI) is used to recognize buried faults. Faults buried by a residue layer and soil may cause the covering layer to be relatively thick, humid and more vegetated. Thus the surface material may have higher thermal inertia and may show relatively low ground temperature in daytime. These effects may be effectively indicated by relative low value of TVDI (which we call negative anomaly). Therefore, negative anomalies of TVDI can be used as indicators of concealed faults. (4) Detailed field investigation is carried out in order to validate the fault identification results and to do further analysis. Numerous natural and manmade outcrops are examined on-the-spot.Using the above methods,we have identified more than20faults which are unknown before, in Yangla mining district. We have investigated the spatial distribution of faults and obtained a detail structure map of the district. This enriches the current knowledge about the basic geology of this region. Based on an analysis of the geometrical and mechnical characteristics of the faults of different attitudes, combined with the regional tectonic background, we suggest that an NE-SW or NEE-SWW stress field played the most important role in this area during formation of the faults. This information may be used to infer missing orebodies dislocated by faults. In a word, the results of this study can be helpful for ore predicting, ore body delimitating and tracing in exploration and mining. It may also provide useful information for further studies of the evolution history of the regional geology of this area.