Accurate characterization of the alteration zoning in Chihu copper-molybdenum deposit by a new tool GeoAHSI in Hami area of Xinjiang

The characteristics of alteration zoning can indicate the hydrothermal alteration activities associated with porphyry deposits, making it the important prospecting indicators for porphyry deposits. Based on fine spectral resolution, the hyperspectral remote sensing data can accurately delineate the spatial distribution of various hydrothermally altered minerals, providing reliable basis for the identification and localization of porphyry deposits. Based on the Teracorder algorithm framework, the authors developed and made open-source of GeoAHSI, a mineral identification tool for domestic hyperspectral remote sensing satellite imagery, to achieve convenient and efficient batch processing and mineral mapping engineering applications of domestic hyperspectral remote sensing satellite imagery. Based on the research basis and field sampling analysis, the GF-5 AHSI (Advanced Hyperspectral Imager) imagery was used as remote sensing data source to carry out surface mineral mapping and verification work in Chihu copper-molybdenum mining area. The results show that AHSI hyperspectral mineral mapping accurately characterized the typical hydrothermal alteration zoning characteristics of porphyry deposits with pyrophyllite+alunite as the advanced argillic alteration core and gradually transitioning outward to kaolinite, pyrophyllite, muscovite and other altered mineral assemblages. Moreover, the mineral map had good spatial distribution consistency with traditional geological mapping units and structures. In addition, the GeoAHSI tool also extracted absorption characterization and wavelength distribution of muscovite in this area, and revealed the relationship between aluminum rich muscovite and porphyry mineralization in Chihu copper molybdenum deposit. The study provides a mature and effective tool and corresponding methods for the identification of alteration zoning for porphyry deposits, which could help promote the domestic hyperspectral remote sensing satellites‘ utilities in the new round of mineral exploration breakthroughs.