Asian Journal of Geological Research

Delineation of Metallic Mineralization Zones using Integrated Aeromagnetic and Geochemical Data in the Basement Rocks of Oba-Akoko Area, Southwestern Nigeria

Wed, 10 Jun 2026 00:00:00 +0000

The Oba Akoko area, southwestern Nigeria, lies within the Precambrian Basement Complex and is characterized by complex lithological units and Pan-African structural deformation. This study delineates metallic mineralization zones using integrated aeromagnetic and geochemical data. Fifteen (n = 15) geochemical samples were analyzed. Aeromagnetic data were processed to produce Total Magnetic Intensity (TMI), First Vertical Derivative (FVD), Euler deconvolution (structural index = 1), and lineament maps, with Euler depth solutions indicating shallow-to-moderate structural sources. Geochemical analysis involved ICP-MS following four-acid (HNO₃–HCl–HF–HClO₄) digestion with 0.45 µm filtration. Statistical evaluation used correlation analysis and Principal Component Analysis (PCA). Aeromagnetic results reveal dominant NE–SW to ENE–WSW structural trends interpreted as deep-seated faults and shear zones controlling crustal deformation and hydrothermal fluid migration. Magnetic highs correspond to mafic rocks, while lows indicate felsic or hydrothermally altered zones. Lineament and Euler analyses highlight structurally dense and highly prospective zones, particularly within the Ikun–Afo corridor. Geochemical results show significant enrichment in IKUN samples with Cu, Zn, Pb, Co, Ni, and Cr relative to background OBA values. PCA identifies hydrothermal (Cu–Zn–As–Pb–Co), lithological (Mo–Th), and mafic (Ni–Cr) associations, while correlation analysis confirms strong Cu–Zn–Pb relationships indicative of sulfide-related hydrothermal processes. Integration of both datasets reveals a strong structural control on geochemical anomalies, with consistent spatial coincidence between fault zones and elemental enrichment. The Ikun–Afo–Okeusi–Oka corridor is identified as the most prospective zone for metallic mineralization due to overlapping geophysical and geochemical signatures. This study confirms the effectiveness of integrated aeromagnetic and geochemical methods for mineral prospectivity mapping in Precambrian basement terrains.

Granulometric Characteristics and Heavy Mineral Composition of Igbokoda Beach Sands, Ondo State, Southwestern Nigeria

A. O. Jayeola — Sat, 13 Jun 2026 00:00:00 +0000

Analysis of grain size distribution has been widely used by sedimentologists to classify sedimentary environments and elucidate transport dynamics. Grain size and heavy mineral content analysis of Igbokoda beach sands, Ondo State, Southwestern Nigeria was carried out to determine the provenance, maturity, industrial and economic significance as well as the economic prospect of the heavy minerals present in the beach sands. For the purpose of this study, a total number of ten (10) beach sand samples were collected along the beach sides in Igbokoda for laboratory analyses. For grain size and heavy mineral content analyses, granulometric and heavy mineral content analyses were carried out on the samples. Grain size analysis was determined by dry sieving the sediments. Granulometric analyses of Igbokoda beach sands showed that Igbokoda beach sands are predominantly fine-medium, clay-free, well-sorted, near symmetrical-fine skewed beach sands with mesokurtic-leptokurtic types ranging from 2.000 mm to 0.063 mm. From the provenance study, the samples were observed to be mature and predicted to have been sourced from a distal source. Heavy mineral content investigation was carried out using heavy mineral separation techniques, which involve using separating funnels and tetrabromoethane, which make up 6-15% of the weight of Igbokoda beach sands. For the purpose of this study, samples were collected from the various sections of the Igbokoda beach sides. For the first section of the beach side, the percentage of concentration of ilmenite is the highest, followed by zircon, pyroxene, rutile, with subordinate amounts of epidote, augite, garnet, apatite, spinel, staurolite and tourmaline. In the second section, almost similar results to the first section were obtained, except in some cases, that is, the concentration of ilmenite and magnetite is lesser, covellite and kyanite are present. From the results, Igbokoda beach sands are predicted to have been sourced from a continental environment and consist of intrusive granitic, metamorphosed and partly sedimentary rock types. However, the beach sands are derived predominantly from intermediate source(s), probably granodiorite. The presence and abundance of heavy minerals like augite, rutile, tourmaline, pyroxene, zircon and others in the bulk composition of the beach sands supports the influence of granitic, gneissic, granodioritic and schistosity sources from nearby crystalline basement complex. Igbokoda beach sands serve various industrial purposes such as filtration, production of glassware and construction.

Geoelectrical Investigation of Groundwater Potential in the Hard Rock Terrain: A Case Study from Lokapavani River Basin, Mandya District, Karnataka

Mon, 15 Jun 2026 00:00:00 +0000

Groundwater in crystalline basement regions is mainly stored in weathered and fractured zones due to the low permeability of fresh bedrock, making its distribution highly variable and dependent on subsurface structural features. Accurate identification of these aquifer zones is therefore essential for sustainable groundwater exploration and management in hard rock terrains. The present study investigates groundwater potential in the hard rock terrain of the Lokapavani River Basin, Mandya District, Karnataka, using the Vertical Electrical Sounding (VES) technique. Twenty-one VES stations were conducted employing the Schlumberger electrode configuration using a resistivity meter (SSR-MP-ATS), with fixed potential electrode spacing (MN/2 = 5 m) and current electrode spacing (AB/2) varying from 10 m to 100 m. Apparent resistivity data were analyzed qualitatively through comparative log–log sounding curves to delineate subsurface geoelectrical variations associated with groundwater occurrence. The interpreted apparent resistivity values range from less than 30 Ωm to greater than 7000 Ωm, reflecting considerable lateral and vertical heterogeneity in subsurface conditions. The VES curves revealed predominantly three- to four-layer geoelectrical models characteristic of crystalline basement terrains. The interpreted subsurface conditions indicate the presence of conductive clayey layers, moderately resistive weathered/fractured basement zones and highly resistive fresh basement formations. Locations characterized by moderate resistivity increase with depth are interpreted as favorable groundwater zones, whereas zones exhibiting very high resistivity values correspond to compact basement rocks with low groundwater potential. The study demonstrates that electrical resistivity sounding is an effective and economical technique for groundwater exploration in hard rock terrains and provides valuable information for sustainable groundwater resource development in the study area.