Characterization of Illite Clays associated with the Sinongduo low sulfidation epithermal deposit, Central Tibet using field SWIR spectrometry

Abstract Field measurements using shortwave infrared (SWIR) reflectance from drill hole samples provided an effective method to map variations in illite crystallinity and the illite assemblage minerals associated with hydrothermal alteration zonation of the Sinongduo low sulfidation epithermal Ag-Pb-Zn deposit, Tibetan Plateau, China. The SWIR mineral spectral information was combined with electron probe micro-analysis (EPMA) measurements, and microscope observations to provide geological insights into: (a) the likely metallogenic fluid nature of the mixture of magmatic fluids and a cooler water source; (b) the illite physico-chemical properties of the associated hydrothermal fluids; (c) the illite ,montmorillonite and sericite evolutionary interactions among these fluids, country rocks, and alteration minerals; and (d) the alteration minerals relationships and illite crystallinity to the economic mineralization. The results suggest that illite characterizations can be used as an indicator for epithermal deposit prospecting.