Alteration Hydrothermal Stage Division and its Application in Geological Prospecting Using CASI-SASI Airborne Hyperspectral Data: Taken the Baixianishan Area in Liuyuan Town of Gansu Province as an Example

The division of the hydrothermal period based on alteration minerals extracted from airborne hyperspectral data has been rarely researched. This work processed CASI-SASI airborne hyperspectral data, and optimized reference spectra from image endmembers based on the expert knowledge in the Baixianishan area. The mixed tuned matched filtering method was utilized to map alteration minerals, and the distribution of limonite, short-wavelength sericite, middle-wavelength sericite and long-wavelength sericite was obtained. Distribution patterns of limonite and three sericite subclasses were analyzed, and three hydrothermal stages were divided. It is considered that the second hydrothermal activity is closely related to the gold deposit. It is proposed that prospecting factors of the Baixianishan gold deposit are NEE-trending fault structure, the vein-like distribution of limonite and short-wavelength sericite. Based on the discuss above, a favorable prospecting section is found in the south of the Xiaobaishan area. It is indicated that the CASI-SASI airborne hyperspectral data can quickly and accurately provide more effective remote sensing criteria at the regional scale for both basic geological survey and mineral resources exploration, which has a wide application prospect in the geological field.