Mapping of hydrothermal alteration zones associated with potential sulfide mineralization using the spectral linear unmixing technique and WorldView II images at Wadi Rofaiyed, South Sinai, Egypt

Abstract

Early investigators mentioned a potential resource of base metal sulfide mineralization associated with quartz diorites and the intermediate Rutig volcanic rocks in the area of Wadi Rofaiyed. The region’s complicated geological history and inaccessibility due to rugged topography makes it difficult to accurately map its lithology on field. A combination of modern exploration techniques is needed to delineate the alteration types and zones associated with sulfide mineralization. This study aimed at mapping the lithology of the study area and delineating the hydrothermal alteration types by classifying WorldView II satellite images using the spectral linear unmixing technique. Thirty training sites that represent all possible lithologic classes and alteration zones were selected and defined using the pixel growing technique. Rock samples were collected from each training site and analyzed using the petrographic microscope, X-ray fluorescence spectrometry, and X-ray diffraction techniques. The spectral library needed to run the spectral linear unmixing model was extracted from the training sites using the VIPER software routine. The spectral linear unmixing technique of WorldView II was successful at distinguishing between different lithologic classes and delineating the K-silicate and propylitic alterations of the quartz diorite and other hydrothermal alterations associated with the andesite and basaltic andesite rock units.