Study On Extraction And Screening Method Of Hyperspectral Alteration Mineral Information In Baogedwula Area,Inner Mongolia

Altered surrounding rock is one of the important marks for the formation of hydrothermal deposits.Altered surrounding rock will produce altered minerals,which have obvious differences in color,structure and chemical composition with the minerals in surrounding rock.These differences can lead to diagnostic spectral characteristics of altered minerals in a specific wavelength range.Hyperspectral remote sensing usually refers to imaging remote sensing with spectral resolution of 5 ~ 15 nm,while the diagnostic spectral width of most altered minerals is 20 ~ 40 nm.Therefore,hyperspectral remote sensing technology can be used to quickly extract altered mineral information.According to the assemblage and distribution characteristics of altered minerals,it is of great significance to divide alteration zoning and delineate mineralization anomalies.However,in practical applications,due to the complex composition of the surface cover,the extraction results contain pseudo-alteration information.Therefore,based on the hyperspectral data of GF-5,this study studies the extraction and screening methods of altered mineral information in the Quaternary shallow coverage area,and establishes the extraction and screening process of altered mineral information.At present,the research on the extraction method of altered mineral information from hyperspectral remote sensing data in the exposed bedrock area has achieved excellent results,but there are few studies on the extraction and screening of altered mineral information in the Quaternary shallow coverage area.In this study,the Quaternary shallow coverage area in the Baogedewula area of Xinbaerhu Right Banner,Inner Mongolia,was taken as the research area.Based on the domestic GF-5 hyperspectral data,the hourglass model was used to extract the endmember information.Based on the spectral angle theory and the spectral feature fitting theory,the endmembers were identified,and the altered mineral information was extracted by the spectral angle matching method.The decision tree classification method was applied to the extraction of altered mineral information,and the new method of extracting altered mineral information in the Quaternary shallow coverage area was preliminarily explored.Finally,three altered minerals of muscovite,chlorite and siderite were extracted by the spectral angle matching method and the decision tree method.Based on the information extraction of altered minerals,the results of two extraction methods were compared,and the genesis of altered minerals,the types of wall rock alteration and the mineralization types of deposits in the study area were analyzed.Landsat7 ETM +multi-spectral data were used to carry out the interpretation of linear structure and annular structure in the study area.Finally,the geological and mineral data,geochemical data,remote sensing interpretation results and information extraction results of altered minerals in the study area were integrated to screen and verify the extracted information of altered minerals,establish the screening process of altered minerals in the study area,and delineate the screening area of altered mineral information,and finally 8 screening areas of altered mineral information(SXQ1-8)were delineated.Among them,SXQ2,SXQ4 and SXQ5 contain known deposits or ore spots.SXQ7 and SXQ8 can be used as prospecting indicators for gold deposits,providing theoretical basis and technical guidance for more in-depth prospecting work in this area,providing new technical means for geological prospecting work in the study area,and providing new ideas for hyperspectral alteration mineral information extraction research in Quaternary shallow coverage areas.