Hydrothermal Alteration Features Enhancement and Mapping Using High-Resolution Hyperspectral Data

Abstract

Hydrothermal alteration mapping is considered as a widely adopted step in the mineral exploration of numerous ore deposits. In this work, the wavelength mapping and relative absorption band depth (RBD) method were applied to map hydrothermal alterations in a site from the abandoned mine of Idikel, western Anti-Atlas, Morocco. Fe2+/Fe3+, Al-OH, and Mg-Fe-OH/CO3 hydrothermal alteration minerals were targeted based on HyMap airborne imaging spectroscopy data. Using the wavelength mapping approach, the 900 to 1205 nm, 2094 to 2217 nm, and 2264 to 2318 nm ranges were selected to map Fe2+/Fe3+, Al-OH, and Mg-Fe-OH/CO3 absorption features, respectively. By carefully selecting these spectral ranges, the study aimed to achieve the accurate and reliable mapping of hydrothermal alteration features. The highest interpolated depth of Al-OH features was matched with a major cluster of pixels at 2200 nm. The highest interpolated depth of Mg-Fe-OH/CO3 was depicted at 2300 nm. The highest interpolated depth of Fe2+/Fe3+ was depicted between 900 and 1000. The relative absorption band depth method was also applied to enhance the detectability of hydrothermal alteration minerals. This method involves assessing the depth of the absorption bands associated with the target minerals, allowing for a detailed characterization of the alteration features. The combination of both wavelength mapping and enhancement methods contributed to a comprehensive and robust hydrothermal alteration mapping process. The identification of Fe2+/Fe3+, Al-OH, and Mg-Fe-OH/CO3 manifestations provided valuable insights into potential mineralization zones within the study area. Overall, this research contributes to the advancement of hydrothermal alteration mapping using hyperspectral data by selecting the required HyMap bands for mapping targeted alterations. The combination of wavelength mapping and enhancement methods proves to be a powerful approach for accurately identifying and characterizing hydrothermal alteration features using specific hyperspectral channels. The findings from this study can aid future mineral exploration endeavors in similar geological settings, providing valuable guidance for locating potential mineral resources in mountainous and challenging terrains.

Keywords

• hyperspectral
• hydrothermal alteration
• RBD
• wavelength mapping