Lithological discrimination and mapping in part of the upper Benue Trough using Landsat 8

Abstract

This study focused on evaluating the efficiency and complementarity of image enhancement techniques for lithological discrimination  and mapping in the upper parts of Benue Trough using Landsat 8 data. To achieve this, image enhancement techniques such optimum  index factor, band ratio, principal component analysis, and minimum noise fraction were applied on Landsat 8 OLI data covering parts of  the Upper Benue Trough. False colour composites (FCC) were created from three most informative derivatives of these image  enhancements. The FCCs were compared in terms of their capability to differentiate different lithological units in the study area by  comparing the FCCs with existing geological map. The results show that the FCC created from band ratios provided the highest amount  of information, while those created based on optimum index factor provided the least amount of information with respect to lithological  discrimination. Additionally, it was observed that the FCCs created from the derivatives of band ratio, principal component analysis and  minimum noise fraction provide complementarity. Thus, the three FCCs from these three enhancement methods were fused into a single image, which further aided lithological discrimination. By combining the outputs from three image enhancement techniques, most of the  sedimentary and crystalline rocks in the study area were successfully delineated. The method adopted in this study particularly the fusion  of outputs from band ratio, principal component analysis and minimum noise fraction represents a novel approach that is suitable  for lithological mapping in remote areas, particularly arid and semi-arid terrains with considerable rock exposure.