Interpretation of aeromagnetic and remote sensing data of Auchi and Idah sheets of the Benin-arm Anambra basin: Implication of mineral resources

Abstract

The need for mineral resources for economic development is key in both developing and developed countries. However, miners usually resort to random excavation of mineral deposits without proper investigation to identify structures of interest in target areas. This usually leads to land depletion and abandonment. The aim of this study is to assess the mineral potential in part of the Benin-arm of the Anambra basin by investigating the geophysical characteristics of the area using remote sensing and aeromagnetic data. Surface and subsurface regional structures, including faults and zones of mineralisation, were mapped by integrating aeromagnetic and remote sensing data. The mineral bearing zones that show high prospects of mineral deposits in the region were identified. The rose diagram revealed that the surface lineaments are aligned in the NW-SE, N-S, NE-SW, E-W, NNE-SSW, ENE-WSW, and ESE-WNW directions. The orientations of the subsurface lineaments are aligned mostly in the NE-SW, N-S, and E-W directions. The magnetic intensity ranged between -431.38 and 399.82 nT, while reduction-to-pole magnetic intensity ranged from -416 to 664.45 nT. The first vertical derivative showed magnetic intensity which ranged from -0.5863 to 0.9060 nT/km2. The total horizontal derivative magnetic intensity ranged from -0.00031 to 0.762691 nT/km2, while the analytic signal showed magnetic intensity ranging from 14.0664 to 394,607.3438 nT/cm2. The windowed Euler deconvolution depth to magnetic source showed depth range of <20 to 2,000 m. Many of the features delineated in the study area were characterised by shallow magnetic source depths (<500 m); this is a common characteristic of basement complex terrains. Deeper magnetic source depths (>1,000 m) were observed in the sedimentary terrain. Mineral exploration should be focused in areas with high lineament concentration, as lineaments are potential conduits for economic minerals deposition.