Identification of altered mineral information in the Wuyishan metallogenic belt based on airborne and spaceborne hyperspectral remote sensing

Wuyishan metallogenic belt is one of the important gold-copper polymetallic metallogenic belts in Mesozoic volcanic rock area in eastern China. To further identify and compare the alteration information of rocks and minerals in the Wuyishan metallogenic belt, with the airborne hyperspectral SASI short-wave infrared data and the space-borne Gaofen No.5 (GF-5) hyperspectral data, based on the analysis of the typical absorption characteristics of the measured spectra for different altered minerals and the recognition and extraction methods of mineralized alteration information, as well the measured spectral characteristics of six altered minerals, namely, dickite, kaolinite, gypsum, chlorite_Fe, chlorite_FeMg, chlorite_Mg, the authors applied Spectral Angle Mapper (SAM) to automatic matched, identify and extract the altered mineral information of hyperspectral images in Yongtai-Dehua-Youxi ore concentration area of central Fujian. The research shows that: 1 Combined with geological data, the two kinds of hyperspectral data can well define the distribution range of the above six typically altered minerals and infer the volcanic structure, suggesting a good prospecting prospect; 2 The comparative study on effect and characteristics of the extracted altered mineral information and the spectral verification of samples in the field indicate the altered mineral information extracted from the SASI data is more consistent with the actual verification point; 3 Through the comparative analysis, it is found that the extraction results of altered mineral information using high spatial resolution SASI data is denser and more accurate than the GF-5 data with low spatial resolution, which is consistent with the conventional understanding that the lower spatial resolution, the more obvious pixel spectral mixing, and the poorer the fine distinction of ground objects. Due to the relatively few spectral verification points, the limited mineral species, and the different original spatial resolution in this study, the evaluation results need to be further verified.