Optimal Selection Of Alteration Information Extraction Method Based On ETM~+Remote Sensing Data

Numerous studies have demonstrated the strong correlation between the altered rocks remote sensing information and metal deposits minelization. Using remote sensing technique to study alteration information in the process of mineralization has a great significance in guiding mineral prospecting. This article analyzes the spectral characteristics of the alteration minerals and designs three models to extract alteration information using ETM+remote sensing data in the plateau sparse vegetation area, which based on the available geological data and in-depth understanding of the alteration types, selects the optimal extraction method by comparing the three models.First of all, the author analyzed theoretical basis of spectroradiometer characteristics and remote sensing basis of geological prospecting, and he studied connection between the types of wall rock alteration with hydrothermal alteration conditions and mineral types, which confirmed the high correlation between the information of the altered rocks and metal deposits. Studied the spectral characteristics of various types of altered rock in the ETM+images, summed up a spectrum belt with the identification of significance with the iron (Fe2+and Fe3+) and containing hydroxyl (OH-), water (H2O) or carbonate (CO32-) ions or groups in the visible light to near-infrared spectrum. Secondly, in the full analysis of the mineralization and alteration remote sensing anomaly information extraction theory foundation and regional geological background basis, using ETM+data were and three types of model to extract mineralization and alteration anomalies in the study area.The three models are:the enhanced mineralization and alteration information extraction model based on the spectral characteristics; alteration information extraction model based on principal component threshold; extraction and classification of the weak mineralization based on spectral vector.Three models played role of the the alteration extraction of the study area in varying degrees. Among them, the pincipal component of threshold alteration information extraction model not only extract the the alteration information but also classify it.Practice has proved that the choice of reasonable extraction method for abnormal alteration information have a good effect, with both fast and economical characteristics, according to the characteristics of the study area based on ETM+images. Like the low level of work in Tibet and poor natural conditions areas can achieve exploration, delineation of mineralization prospect area rapidly, and have a great significance for the discovery of a large deposit or ore concentration area.Application of multi-spectral data to extract the mineralized alteration information to guide the pospecting has a great significance,because of the resolution limitations of multispectral data, the remote sensing geoloy work of Jiama copper polymetallic deposits in the future will develop to quantitative remote sensing direction, take full advantage of high spatial resolution and high spectral resolution remote sensing data, develop fine material classification. Strive to collect typical spectral information of mineral rocks, and establish typical spectrum repository in mining area; further improve the relationship between remote sensing information with the mineralization, explorate, develop and constructe remote sensing rock and mineral information extraction optimal combination model and system integration.