The Research Of Using Multi-Spectral Remote Data For Alteration Information Extraction In PuXiong, Yunnan Province

Almost all the existence of hydrothermal deposits goes with rock alteration. In general the scope of altered rock is far greater than ore bodies. Found the altered rock also often means that there may be hydrothermal deposits. So wall-rock alteration can be used as an important exploration target. Alteration mineral has its own unique spectral characteristics, so use of remote sensing images can delineat altered area quickly. The result can be combined with geophysical and geochemical data analysis. In this way, we can achieve rapid prospecting purposes.Gejiu is an important tin, copper multi-metal mineral area in Yunnan province. Tin resource development and utilization occupies a pivotal position in the economic of the city. However, after a large-scale exploitation which lasted several decades, the current number of old tin mines are faced with resource depletion. The external prospecting and deep exploration to find a new point has become a top priority of mine. Gejiu fracture which across north-south of the city has divided the tin mines into Eastern, Western two parts. The Eastern is the exploitation of deposits in the main concentration area, a high degree of geological survey. The five old mine -Magela, Songshujiao, Gaoshong, Laochang, Kafang are scattered in the area; The Western part has few known deposits. And the geological exploration and development is low level at this area. Therefore it's a target area for long-term expansion of mining prospecting.Puxiong area is in the western area of Gejiu. It's belongs to Jianshui County of Yunnan Province. The Straight-line distance to the southeast city town is 2.5 km. It's geographic coordinates is east trail 102°58', latitude 23°30'. The acreage of the area is about 300 square kilometers. Since 1954 The Geological Survey team of the Yunnan USGS has conducted a number of geological survey works for the area. They found some sporadic occurrence from the work, but had found nothing of significance. This shows that the traditional method of prospecting in the area has been very difficult to make a difference; we must adopt new methods and theories, breaking the limitations of traditional methods.In this paper, we depend on the horizontal cooperation projects "Puxiong lead multi-metal ore belt deep concealed ore project" to carry out exploration of remote sensing information extraction. In the case, we major study of the following:1. Study of the alteration minerals extracted from the geological basis and alteration of the spectral characteristics of minerals. Discusses the relationship between the altered rock and mineral introduced several major characteristics of the surrounding rock alteration and its implications for prospecting guiding significance. Generation mechanism from the atomic spectra, crystal field effect, charge transfer, etc. discussed the physical mechanism of the formation of rock and mineral spectrum in this study based on the typical spectral characteristics of alteration minerals.2. Regional geological background and the characteristics of rock alteration.Study the geological background of the Puxiong ore mining area. Give a brief summarize of the basic situation of the study area. We do research on the construction of the regional stratum construction, regional geological structure, the regional magma construction and magma rocks, regional distribution and the characteristics of mineral. Finally, we analyze the type of wall-rock alteration and its sub-zone characteristics, and their relationship with the region of the study area basic on the study of mineral, the combination of regional geological.3. Regional remote sensing image acquisition and processing.Mainly to obtain a series of ASTER raw data processing, including geometric correction, sub-area selection, radiometric and atmospheric correction. We do a statistical analysis of remote sensing images of the study area; select the optimal band for color composite.4. The interpretation of remote sensing wire loop construction and extraction.A variety of methods has been used on the ASTER image to enhance remote sensing images. Base on it, we construct the interpretation of signs for the linear structure and circular structure. We extract the ine and ring structures of the study area from the ASTER images. Finally the result combined with geological data was analysis.5. The alteration minerals alteration spectral analysis and remote sensing information extraction.The spectra of the altered rocks of the study area were analyzed. In particular, we analyses the reflectance or absorption characteristics of the spectra in each band of the ASTER image. Based on the removing of the interference information (vegetation, water, etc.)to the Alteration Information Extraction, we adopt a variety of methods for alteration of information extraction based on the study of the spectral characteristics of alteration minerals.6. Metallogenic prediction based on GIS PlatformIn the end, geological, geophysical and geochemical favorable ore-forming information of the study area have been integrated. Based on the GIS platform, we do a comprehensive analysis of multivariate information.The above study got the following conclusions and results:1.Faults in this area have a high degree of development and have close ties with the mineral. Faults in constructing orient the form of small folds and faults. Faults and mining are very close. Close to the Long Chahe rock T2g the main distribution are zinc, iron, manganese, molybdenum and other mineral point, these mine sites along the Long Chahe limestone rock contact zone with the old distribution, subject to Nanling latitudinal structural system under the control of the complex. By Lihaizai secondary faults and large faults control the impact of large faults. Near the Lihaizai Jiutoushan, Banshan, near the village of Da luoShuidong have also focused on the distribution of lead, zinc, iron, manganese, molybdenum and other mineralization. 2. Using remote sensing images for faults extraction is feasible and effective. Faults in remote sensing images on the signs are very clear, through the original remote to make the appropriate enhancements, combined with visual interpretation; you can quickly interpret regional tectonic information. Caring out the follow-up geological work are very favorable by this.3. Rock alteration in this area is strong and has very close relationship with the mineral. Puxiong tin-lead-zinc mine metal deposits in the general existence of altered rocks assigned among the various types of altered rocks surrounding the granite intrusion, the formation of altered circle, rarely found in deposits beyond this range. It also means that, in this area, once we find the corresponding wall-rock alteration, is likely to find the corresponding deposit.4. In the middle vegetation coverage area using ASTER data can also extract good alteration anomalies. This study area is located in Gejiu area,Yunnan province. The vegetation coverage is high, it is normally considered in this case is not suitable for alteration of information extraction. Usually in the area of the alteration information extraction work shows that in secondary vegetation areas, through the information model to optimize the extraction can also have a good effect. Altered the results of the final extracted most of the mining points and the known coincide, which proves that alteration in this area using remote sensing information extraction to the idea of exploration is feasible.5. Remote sensing can be used as an alteration anomalies and geological, geochemical and geophysical prospecting indicators are equally important. In the past, remote sensing information only as a secondary information of geological prospecting not given adequate attention. In fact, give full play to regional coverage of remote sensing light, the investigation from natural conditions, etc., can greatly speed up the exploration process. This study fully demonstrates this point.6. Individual extract information of remote sensing needs to combination with geological, geophysical and geochemical exploration for comprehensive analysis. The results of the analysis are more accurately possible. This research demonstrated that remote sensing interpretation of geological structure, mineralization and alteration of information can be used as geological, geophysical and geochemical parameters are equally important applications in the evaluation of mineral resources, its has very important significance for the rapid evaluation of. mineral resources.In this paper a combination of geological, geophysical and geochemical information on the use of evidence-based GIS platform to the right of France conducted a comprehensive analysis and delineation of a number of ore prospecting area. There are:①Xiazhichang-Large Montenegro regional target area: the area in the deep and external have a greater potential for mineral resources is the greatest potential for mineral resources in this area one of the areas should serve as a focus of the work in this area.②Luoshuidong-Panshan area: the area to find small-scale mining points, superficial likely mine sites can be used as the next focus of work.③PuJiashan target area: There are ore-forming geological conditions, could be further investigation.Although this study had some success, but there is much to be desired. Studies have identified the urgent need for follow-up study following address: 1. The extraction of structural information in remote sensing, even though it made a lot of image enhancement, but mainly to get results based on visual interpretation, so that there is a strong subjectivity. The further study for automatic extraction of remote sensing wire ring structure is needed.2. Typical of the study area of mineral spectrosccpy study, only the typical features in spectra collected do not take full account of weathering, su face color and rock particle size on the impact of mineral spectrum. In the case of a conditional should try to collect different kinds of mineral samples for their further study.3. ASTER band due to the limitations, limiting the choice of extraction method altered. Many rock and mineral can be accurately identify the high-spectral methods can not be applied. In the conditional case, hyper spectral data can be used for further study.4. Remote sensing exploration in the whole workflow defined circumstances, be considered for system integration, develop a comprehensive GIS & RS based on the extraction analysis platform, enabling workflow automation.