Integration of Aeromagnetic Data and Landsat Imagery for Structural Analysis: A Case Study of Awgu in Enugu State, South-Eastern, Nigeria.

In this study, digital format data comprising of aeromagnetic and remotely sensed (Landsat ETM+7) data were used for structural interpretation of the Awgu area in Enugu State, southeastern part of Nigeria, predominantly underlain by sedimentary rocks. Aeromagnetic data were analyzed using the Oasis Montaj 7.5 software and interpretation was carried out using the vertical and horizontal gradients, analytical signal, reduction to pole, tilt depth as well as Euler deconvolution. The total magnetic intensity map shows a magnetic signature ranging from -39nT to 129nT. The 3D Euler solution of the study area has a structural index of 1.0 with dyke/fault as the shape of the inferred geological structure. In the Landsat ETM+7 satellite data used, band 5 was found as the most suitable band in (automatic) delineation. The automatic lineament extraction process was carried out with line module of PCI Geomatica 2015 version. The essence of analysis and interpretation of the Landsat ETM+7 was to determine the lineament trends and density across the area. Rockworks 16 version software was used to generate the rose diagrams. The aeromagnetic and Landsat lineament maps of the study area have been summarized using rose diagrams, revealing NE-SW as the major trend with some secondary trends NW-SE, E-W and N-S directions. However, the NE-SW trend reflects the younger tectonic events, because the younger events are more pronounced and tends to obliterate the older events. The comparison of the aeromagnetic and Landsat lineament extraction of the study area in terms of number of lineaments, directions and total length of lineaments, the Landsat imagery were found to be more than the number, directions and total length of the aeromagnetic data.