Mapping hydrothermal alterations and associated lineaments within Kaiama, north-central Nigeria, using Landsat 8 Operational Land Imager Data and Digital Elevation Model

Abstract

This research focuses on the geological investigation of Kaiama region, which is characterized by a diverse range of rock formations, including mylonites, porphyritic granites, gneiss, schist, phyllites, and pink granites. The study employs remote sensing techniques, utilizing Landsat 8 OLI data and Digital Elevation Models, to systematically map the spatial distribution of hydrothermal alterations and tectonic structures associated with mineralization in the Kaiama area. Various image processing methods such as Color Composites, Band Rationing, and Principal Component Analysis (PCA) were employed to extract valuable information from the collected datasets. Utilizing Sabins band ratios (4/2, 6/7, and 6/5), we categorized alterations associated with iron oxides, clay minerals, and ferrous minerals. PCA was applied to refine the identification of alteration zones, using two distinct sets of images: H-image (comprising bands 2, 4, 5, and 7) and F-image (comprising bands 2, 5, 6, and 7), which represented iron-oxide and hydroxyl mineral deposits, respectively. The synthesis of H, F, and H+F images in RGB format provided an optimal representation of the spatial distribution of hydrothermal alterations, exhibiting a strong positive correlation with known mining regions for gold, copper, wolframite, and tantalite within the study area. Furthermore, a comprehensive analysis of regional lineaments revealed a consistent NNE-SSW to NE-SW correlation, suggesting a predominant control on mineralization trends. This study advocates for adopting remote sensing techniques, specifically Landsat 8 data and DEM, as an effective approach for mapping hydrothermal alterations and identifying key structural controls associated with mineralization.