Delineating Solid Mineral Structures in a Portion of Nasarawa State, Nigeria, using Aeromagnetic and Aeroradiometric Data

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Delineating Solid Mineral Structures in a Portion of Nasarawa State, Nigeria, using Aeromagnetic and Aeroradiometric Data.

Abstract:
This study focuses on the analysis of aeromagnetic data to delineate the structural features of the upper part of Nasarawa State, Nigeria, including the regions of Kuje, Keffi, and Akwanga. The identified structural features consist of lineaments, faults, and folds, which serve as pathways for the accumulation of solid minerals. Various enhancement techniques, such as horizontal derivatives, first vertical derivative, and analytical signal, were employed to aid in delineating these features.

The investigation resulted in the production of concentration maps for three radioelements: Potassium (K), Thorium (Th), and Uranium (U). Additionally, ternary and ratio maps, including K/Th, U/K, and U/Th ratios, were generated. The analysis of the residual magnetic intensity (RMI) map revealed regions with different magnetic susceptibility, corresponding to various lithologies and depths of source rocks. The RMI values ranged from -25.0 to 110.7 nT, with high magnetic signatures predominantly found in the north-eastern and south-western parts of the study area, corresponding to Akwanga and Kuje regions, respectively. The sedimentary region in the extreme south-eastern part of the map exhibited low magnetic intensity.

The horizontal derivatives depicted a mix of low and high magnetic closures with short wavelengths and high frequencies of occurrence across most of the area. Some areas with relative sedimentation showed averagely long wavelengths. The analysis of the first vertical derivative map revealed fault zones, lineaments, and intrusions, with lineaments predominantly trending in the NE-SW direction and fault lines mostly in the NE-SW and E-W directions. The analytical signal showed an amplitude range of -119.1255 to 28.4702 nT/m, with most lineaments, faults, and intrusions exhibiting high analytical signal values. The sedimentary region, on the other hand, displayed low analytical signal values.

Furthermore, the K/Th ratio map indicated regions with high K/Th ratios, particularly in the biotite-granite region near the contact with the sedimentary rock in the south-eastern part of the map. A long stretch of lineament located towards the south-western area displayed a high K/Th ratio. Conversely, the sedimentary region in the extreme south-eastern part of the map showed low K/Th ratios. These areas with high K/Th ratios are potential regions of hydrothermal alteration and, thus, potential areas for gold mineralization.

The ternary map corroborated the regions of hydrothermal alteration identified in the K/Th ratio map. Additionally, the biotite granite intrusions at specific coordinates showed high concentrations of K, Th, and U. The magnetic lineaments representing fractures, where hydrothermal alteration occurred, were identified as potential hosts for gold minerals. Furthermore, rocks associated with high magnetic anomalies along these fractures were identified as conduits for solid mineral accumulation.

Delineating Solid Mineral Structures in a Portion of Nasarawa State, Nigeria, using Aeromagnetic and Aeroradiometric Data.  GET MORE, ACTUARIAL SCIENCE PROJECT TOPICS AND MATERIALS

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