| Xiongcun copper-gold deposit is superlarge porphyry copper-gold deposit,which located in the middle of gangdese metallogenic belt, the southern margin of the eastern section of gangdise mesozoic and cenozoic volcanic-magmatic arc, southern edge of the brahmaputra discordogenic fault,magmatic arc and angren-xigaze cenozoic fore-arc basin conversion parts. In recent years,because of a large number of porphyry copper-gold deposits were discovered,gangdese metallogenic belt received much concern.Wall rock alteration is the main indicator of looking for porphyry copper deposit due to intimately associated with mineralization by study for metallogenic mechanism of porphyry copper deposits.Make use of good weather conditions in western alpine mountain areas,and the advantages of shallow overburden,using of remote sensing technology study about porphyry copper mineralization information extraction method,and provide the basis for prospecting potential in perimeter zone of xiongcun copper-gold deposit.Making use of ASTER remote sensing data,under the guidance of regularity of ore formation of porphyry copper deposits,and combined with existing reconnaissance material,analysis for spectral characteristics of alteration mineral, and then to determine the best extracting method in connection with various types of alteration.Based on the analysis of regional geological features,using of ETM data to interpret linear and ring structure,analysis of the mineralization vantage point associated with the construction,finally,the various types of remote sensing mineralization information were integrated into a unified geographic information system platform,and then comprehensive analysis of remote sensing geological mineralization information, finally to metallogenic prognosis for the study area.The main content of this paper as follow:(1)Based on the completion of the ASTER data pre-processing and removal of interference information,using of the spectral recognition advantages of ASTER data in the near infrared,short wave,under the guidance of porphyry copper deposit's typical alteration zoning mode,proposed the method of altered extraction is based on principal component analysis.Analysis and summarized the typical distribution pattern of the alteration zone in distribution of clusters of the study area.(2)Analysis for existing reconnaissance material of xiongcun copper-gold deposit and extracted results of typical alteration zoning,determine the additional alteration types which need extracted,excluding the typical alteration zone has little effect on mineralization,ultimately five category of alteration as mineralization information, which are potassium alteration,quartz-sericitization,beresitization, siliconization,and obtained the general distribution characteristics by the superposition of five category of the alteration results:potassium alteration- potassium alteration+quartz sericitization-quartz sericitization.(3)Making use of the mature experience at remote sensing geological interpretation for ETM data that consists of band 741,carry on remote sensing visual interpretation of geological information in the study area,mainly include that linear and ring structure interpretation,and quantitative analysis for the result of remote sensing geological interpretation,analysis of structure concentrated area and main orientation,than though linear-ring structure model for ore deposit loeation to decide the favored site of mineralization.(4)Comprehensive analysis for remote sensing geological mineralization information,first,alteration and linear-ring strueture were integrated into a unified geographic information system platform,and recevied the remote sensing metallogenic factor map. Production linear-ring strueture density map, evaluation for every alteration types and production alteration density map.By testing determine the best weights and use of raster calculator for two types metallogenic factor, and obtained favorable metallogenic classification map.Based on favorable metallogenic classification map, ten predicting areas of porphyry copper deposit were delineated.The position of predicting area is coincide with xiongcun copper-gold deposit's,this result validate the effectiveness of remote sensing geological mineralization information extraction. |
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