Processing and analysis of aster and landsat 8 scenes to aid in geological mapping: A case study of murchison greenstone belt area, South Africa

Abstract

This paper presents processing and analysis results of ASTER and Landsat 8 scenes to aid in geological mapping of Murchison Greenstone Belt region of Limpopo Province, South Africa. Images of ASTER acquired in 2005 and 2006 and Landsat 8 acquired in 2019 were downloaded and subset covering 5 mapping sheets was extracted. Images of different band ratios and band combinations were experimented using ENVI and SNAP software to identify suitable band/band ratio combinations to produce FCCs that enabled discrimination of lithology, structural features, lineaments, alteration and iron oxides, land/ water, surface features, vegetation cover and healthy vegetation etc. Using DEM data, slope and shaded relief were also prepared that enabled the iden-tification of the extent of protruded outcrops, some structural features and lineaments using different FCC displays. These datasets prepared in ENVI file format were later exported to GeoTiff/Imagine file for display in ArcMap by the mapping geologists. FCCs made in various band combinations, ratio combina-tion and also with slope are useful in discriminating geology, structural features and protruded outcrops including dykes that are not so visible in a true colour image of the same resolution. This study could illustrate the usefulness of remote sensing analysis to aid in geological mapping using freely available ASTER and Landsat 8 data.