Extraction of mineral alteration information from core hyperspectral images based on weight of absorption peak

Abstract

Aimed at overcoming the defects of the spectral angle mapping( SAM) in extraction of mineral alteration information from core hyperspectral images,the authors proposed an improved method based on a weight in the absorption valley in hyperspectral information identification. Firstly,through necessary reflectivity conversion,noise filtering and selection of end- members in the original image,the authors systematically analyzed the diagnostic absorption features of three typical types of altered minerals closely related to uranium mineralization( i. e.,illitization,chloritization and carbonatization) in the core hyperspectral image. Then a range called feature range was selected which has little difference between the same kind of altered minerals on their spectral curves. The authors used SAM between end- members and pixels in this feature range after setting up a weight on absorption peaks within a band scope,and finally achieved the recognition and extraction of these three typical uranium mineralization alteration minerals. The method proposed in this paper highlights the important part of spectral information and its absorption peak,and can better cluster the same kind of alterations and distinguish different alteration types. Contrasting and precision test results show that the accuracy can be improved by over twenty percent when ω = 2,and the application effect of extracting information of altered minerals from core hyperspectral image is remarkable.