LAUSR

ABSTRACT Hyperspectral technology can quickly identify hydrothermal altered minerals and can locate the possible hydrothermal/mineralization centres through the variations of the spectral characteristic parameters of some specific altered minerals. In this study, airborne sensors Compact Airborne Spectrographic Imager (CASI)/ Shortwave infrared Airborne Spectrographic Imager (SASI) and visible-shortwave infrared spectrometer FieldSpec4 hyperspectral data were used to study the alteration characteristics to locate the possible hydrothermal/mineralization centres for the Baiyanghe uranium deposit, Xinjiang, NW China. The results showed that the hydrothermal altered minerals mainly included white mica (it is a general term for aqueous silicoaluminate mineral group, and mainly includes muscovite and illite in the text) (Al-rich, Al-median, and Al-poor white mica), montmorillonite, kaolinite, chlorite, carbonate, and ferric iron (Fe2O3, and the ferric iron alteration usually presents red, mainly hematite in the text); and that the alteration had obvious zoning characteristics. The variations in the absorption-peak wavelength of white mica at 2200 nm, SWIR-IC (short-wavelength infrared illite crystallinity, a dimensionless quantity, and it is defined as the absorption-peak depth of illite at 2200 nm divided by the absorption-peak depth of illite at 1900 nm on a hull quotient spectrum) of white mica, and acid–base properties revealed that the possible hydrothermal/mineralization centres were located in the northern contact zone between the Yangzhuang rock body and the northern volcanic rocks of the Devonian and in the acidic alteration zone to north of the deposit about 3.0–4.0 km, where there appeared a certain number of uranium mineralization occurrences. These results pointed to the existence of multiple hydrothermal activities and could provide references for periphery uranium exploration and geological origin of this uranium area.