Application of aeromagnetic and vertical electrical sounding to investigate groundwater potential in Dutse and Environs, Jigawa State, Nigeria

Aeromagnetic data acquired over the Obudu Plateau, Ikom Mamfe embayment, and Oban Massif was analyzed to evaluate the study area's structural pattern and sedimentary thickness. Data filtering and other enhancement methods with 2-D forward modeling were applied to total magnetic intensity (TMI) data to evaluate the structural pattern, possible mineralization potential, sedimentary thickness, and basement framework disparity. To achieve this aim, several data enhancement techniques such as first vertical derivative (FVD), second vertical derivative (SVD), total horizontal derivative (THD), tilt angle derivative (TAD), analytic signal (AS), upward continuation (UC), low pass filter (LPF), high pass filter (HPF), Centre for Exploration Targeting (CET) and 2-D forward modeling were performed on the TMI data from which the buried subsurface structural lineaments and trends were unraveled. The structural lineaments delineated from the various enhancement operations revealed the major structural orientations of NE-SW. In contrast, the minor geologic structures trend in NNE-SSW, NW-SE, N-S, and E-W directions. These high frequency magnetic anomalies (geologic structures) are caused by post-depositional magmatic intrusions occurring at shallow depth and they have significant control over mineralization. They serve as migration pathways for hydrothermal fluids and accumulation zones for minerals. The depth estimation techniques like source parameter imaging (SPI), standard Euler deconvolution (SED) and 2D forward modelling employed in this study, revealed predominantly shallow depths (< 1400m). These thin sedimentations are attributed to the widespread presence of Precambrian basement rocks in the Oban Massif and Obudu Plateau as well as the significant basaltic intrusions of Ikom-Mamfe Embayment. Furthermore, the 2-D forward model along the SW-NE profile revealed sediment thickness of 0-700m overlying intruded metamorphic basement with magnetic susceptibility values ranging from 0.00001 to 0.00625 SI. The model which is highly undulant, revealed two sub-basins separated by the magmatic intrusion.

The Jurassic Younger Granite (JYG) Province in Nigeria is notable for its rich mineral resources, though much of its subsurface wealth remains unexplored. This study utilizes integrated magnetic geophysical techniques to assess the region’s concealed mineral potential. High-resolution aeromagnetic data was employed to map geologic structures, lithological variations, and zones of mineralization. Advanced filtering methods, including reduce to magnetic equator (RTME), Butterworth bandpass filter, analytical signal (AS), tilt derivative (TRD), and first vertical derivative (FVD), alongside depth estimation tools like source parameter imaging (SPI), Euler deconvolution, and 3D magnetic inversion, were used to uncover new mineralization patterns. Magnetic anomaly maps reveal variations in magnetic intensity, indicating rock bodies with differing magnetic properties. The RTME map shows deeply seated deformations, while TRD and Rose diagram analysis identify NE-SW and minor E-W fault and fold trends related to Pan-African orogeny. FVD and phase symmetry analysis indicate granitic rock intrusions, contributing to intense faulting and folding. The AS map highlights minor magnetic irregularities tied to deposits of tin, columbite, and monazite. Depth estimations using SPI indicate shallow magnetic sources, concentrated in the central and northwestern regions. Euler deconvolution, with a structural index of 0, identifies clusters of solutions interpreted as dykes and sills at depths of 100–300 m, with E-W trending structures. 3D inversion model reveals evidence of geologic structures that can host appreciable mineral deposits in the region. These results demonstrate a strong correlation between magnetic anomalies and known mineral deposits, suggesting further untapped resources. This integrated approach highlights the effectiveness of magnetic geophysical techniques in mineral exploration and offers a foundation for similar studies in comparable geological settings.

The Ilesha and Ado-Ekiti areas are characterized by extensive mineral potentials, including both metallic and non-metallic resources. To detect the probable zones of mineralization, airborne magnetic and radiometric data were applied to map lineaments and lithological components. o generate comprehensive structural maps, the Centre for Exploration Targeting (CET) grid analysis tool was applied to total magnetic intensity data upward continued to 100 m, First Vertical Derivative (FVD), Second Vertical Derivative (SVD), Analytic Signal (ASIG), Tilt Angle Derivative (TAD), and Total Horizontal Derivative (THD) grids. The structural maps strongly correlated with each other were observed to be characterized by polyphase deformations, and oriented in the NE–SW, N–S, and E–W directions. The dominant NE–SW trend is related to the Ifewara-Zungeru zone caused by the Pan-African Orogeny and other tectonic events. Distinct lithological areas were mapped using radiometric anomalies. A major lineament that falls within the potassium-rich and magnetically concentrated zone indicated possible igneous related gold site. In general, the lineaments that have been detected are probable hosts for metallogenic minerals. Furthermore, the depth estimate involving the Source Parameter Imaging (SPI) and Standard Euler Deconvolution (SED) detected thin sedimentation (≤ 482 m).

Summary High resolution aeromagnetic data was analysed and interpreted both qualitatively and quantitatively to delineate the occurrence of porphyry mineral deposits (Gold) in Birnin Gwari and environs, North-Western, Nigeria. The Residual Magnetic Intensity (RMI) anomalies extracted were reduced to equator, thereafter enhancement procedures (First Vertical Derivative (FVD), Tilt-angle Derivative (TDR) and Analytical Signal (AS)) were carried out on the resulted reduced to equator grid of the RMI to improve the quality of the aeromagnetic data for better understanding of the subsurface geology. The RMI revealed several geologic structures which are related to dykes/faults striking predominantly in the NS, NNE-SSW, NE-SW and NW-SE directions. Geological structures delineated as high amplitudes in the analytical signal derived map which are the most significant concentration of mineralization zones in the study area established a positive correlation with CET grid analysis while the CET porphyry analysis map highlights high occurrence of circular and near circular features (porphyry like features). The depth estimation applied using analytic signal and Source Parameter imaging (SPI) techniques show comparable results. The depth to the top of the basement sources ranges from 933 to about 2664 m in the study area.

The accurate mapping of mineral resources in rainforest areas is challenging due to dense vegetation and thick lateritic cover obscuring rock outcrops. This study utilized airborne magnetic survey data to map geological features and target mineral resources in the Ambam-Amvom area at the NW margin of the Congo craton. Linear and non-linear filtering algorithms were used, including reduction to the equator (RTE), upward continuation (UC) at 1000 m and 2000 m, first vertical derivative (FVD), and analytic signal (AS). Field surveys were carried out for sampling and petrographic investigations. The TMI map showed magnetic signals varying from -4489 nT to 2317 nT, while the RTE map displayed magnetic signals varying from -2984 nT to 3528 nT. The RTE-Reg map exhibited anomaly signal variations ranging between -2704 nT and +3637 nT and between -2829 and +3864 nT, respectively for UC at 1000 m and 2000 m. Geological structures were interpreted from the FVD, AS, and TMI-RTE images, and linear structures of regional extend mainly trend NW-SE, E-W, and NE-SW. Field investigations revealed that the study area comprises iron formations, amphibolite, gneiss, gabbro, biotite granite, and charnockite. The bulk chemical composition of iron formations showed a high content of TFe, averaging 39.80 wt.% for itabirite, 53.79 wt.% for hematite-geothite ore and 59.63 wt.% for quartz-hematite ore. The zones of peak magnetic anomalies coincided with the occurrence of the greenstone belt, and the integration of aeromagnetic and geological data led to the identification of three main target zones for iron ore minimization. High fracture density zones within the research were identified as high prospective targets for gold mineralization. The study's findings highlight the high potential of the Ntem Complex for mineral resources and provide valuable information for future research and development.

This study centers on investigating the subsurface condition of the north-eastern part of the Sokoto Basin using aeromagnetic data for geological structures. This area falls within the Sokoto Basin, the Nigerian portion of the Iullemmeden Basin, and covers four adjacent quarter-degree sheets of Gada, Sabon Birnin, Rabah, and Isa. Qualitative and quantitative interpretation techniques which include First and Second Vertical Derivatives, Upward Continuation, Analytic Signal, Source Parameter Imaging, and Euler Deconvolution were employed. The first and second vertical derivatives applied show the response of the target structures, which helps to remove noise caused by high-frequency shallow anomalies. The analytic signal map shows high analytic signal amplitude most prominently around the east-west flank, with low analytic signal value towards the centre, with amplitude ranging from 0.00 nT to 0.08 nT. The data was subjected to upward continuation at 2 km, 5 km, 10 km, and 15 km with magnetic field values ranging from 7.25 nT to 84.27 nT, 17.73 nT to 74.46 nT, 22.17 nT to 68.86 nT, and 23.83 nT to 67.12 nT, respectively. The result shows the magnetic anomaly for deep-seated features becomes more obvious by projecting from a lower elevation to a higher elevation, thereby removing noise caused by high-frequency shallow anomalies.

Reducing ambiguities in vertical electrical sounding interpretations: A geostatistical application

The hidden objects are located, as sixteen objects (anomalies) on the reduction to magnetic pole data (RTP). The follow-up and identification of these objects by applying several digital filters, as upwarding continuation at different level, then the horizontal derivative (HD) and vertical derivative (VD). Accordingly, the edge detection filter techniques are dependent on the tilt derivative (horizontal, vertical derivatives) and the tilt angle. This study shows closing to the basic dykes (shallow anomalies) that imprinted in the RTP map and the upward continuation maps at shallow levels. The residual features are mostly starting to disappear gradually in the upward continuation maps at intermediate and deeper levels. The last upwarding maps illustrate the penetrated roots of these bodies to deep levels (deep anomalies). The advanced filter technique of edge detection is the enhanced total horizontal derivative of the tilt angle (ETHDR). This study delineates and compares the hidden objects by applying the different filter techniques, as the analytical signal (AS), first vertical derivative (FVD), total horizontal derivative (THDR), tilt angle (TA), horizontal tilt angle (TDX), and ETHDR. The applied derivative-based filters, as ETHDR, produce more detailed results for the shallower and deeper magnetized structures. The compared filter results such as TA, TDX, and ETHDR give sharp edges of the magnetized sources (hidden objects). Quantitatively, the determined depths have been evaluated, using the 2D modeling algorithm. The depths and relief of the basement surface across eight profiles are defined, and the depths and shapes of the hidden objects are outlined. Meanwhile, magnetic susceptibility contrasts of the hidden objects are varied with different expanding shapes and subsurface depths.

Bakreswar geothermal area in West Bengal is one of the few groups of geothermal areas in the Chotanagpur Plateau in eastern India which are characterised by surfacial manifestation of a cluster of springs (35O-88OC) mostly issuing out of fractures in a Precambrian cratonic mass comprising predominantly granitic rocks with sedimentary outliers of Gondwana Formation. Wenner resistivity profiling, Vertical Electrical Sounding (VES) and geological studies in the area reveal the presence of a nearly N-S trending and easterly dipping hidden fault that provides outlets for upflowing thermal water to emerge as springs. VES results indicate the presence of three to five lithological layers under the prevailing hydrodynamic conditions. The intermediate weathered zone and fractured rocks togetherly constitute an unconfined regional aquifer; sparsely occurring artesian aquifers are detected within the basement granite gneiss. The VES findings are also in good agreement with the borehole lithologs. Moreover, VES results indicate few ground- water potential zones of apreciable thickness in the eastern part of the fault. A comparative study on chemical compositions of thermal spring waters with adjoining cold groundwaters indicates that thermal waters are Na-SO,-Cl type with alkaline pH while the groundwaters are mostly Na-HCO, type with near neutral pH.

Vertical Electrical Soundings (VES) provide fast and economical measurements used in geophysical exploration. VES were carried out in El Sauz-Encinillas (ESE) aquifer, in northern Mexico, to determine apparent resistivity and geoelectrical units’ thickness. Despite it being one of the three main aquifers feeding Chihuahua city, a lack of available geophysical data prevails in its northern portion. The main goal of this study was the determination of the geoelectrical units in the subsurface stratigraphy via electrical-resistivity soundings. The ESE’ aquifer is located within alluvial Quaternary sediments, with varying granulometry and reaching from a few meters to more than 600 meters of thickness at the center of the valley. Forty-five vertical electrical resistivity soundings (Schlumberger array, maximum AB/2 distance of 500 m) were performed throughout ESE aquifer’s northern portion. Field data were analyzed using software. Results illustrate a wide variability in resistivity values throughout the study area. Five geoelectrical units were identified: 1) a hardpan topsoil, with resistivity values ranging from 200 - 800 Ω-m ; 2) an alluvial material mixture (sand/silt) with resistivity values ranging from 25 to 100 Ω-m; 3) playa lake-type material (clay/evaporites mixture) with resistivity values ranging from 0.2 to 15 Ω-m; 4) a gravel/sand mixture with resistivity values from 100 to 300 Ω-m; and 5) a partly fractured rock or conglomeratic material with resistivity values ranging from 400 to 3500 Ω-m. The electrical resistivity data, therefore gives reasonably accurate results that can be used to understand the subsurface stratigraphy and basement configuration in groundwater exploration.

Significant yet untapped resources still abound in the Nigerian sector of the Dahomey Basin. Although the presence of an extensive Cretaceous Petroleum System has been confirmed following recent discoveries in Aje and Ogo Fields offshore Lagos, exploration outputs in the Dahomey Basin has so far not been encouraging. Proper understanding of the basement architectural framework and controls on tectonic development remains key to unlock the unrealised potentials in the basin. Hence, a geophysical interpretation of the basement structure and architecture of the Dahomey Basin southwestern Nigeria has been carried out in this study. Various edge enhancement techniques were applied to the high-resolution residual magnetic intensity (HRRMI) grid of the area. This includes first vertical derivative (FVD), total horizontal derivative (THDR), tilt derivative (TDR) and total horizontal derivative of upward continuation (10 km). Determination of the depth to magnetic sources and sedimentary thicknesses in the study area were achieved using standard Euler deconvolution and source parameter imaging (SPI) techniques, with depth range of 4.5–6.3 km attained in the two identified sub-basins located offshore of the study area. Lineament analysis gave insights on the tectonic trends and stress-field orientation in the basin with major trends in the NNE-SSW, NE-SW, NW-SE, and WNW-ESE directions. 2D forward modelling of some selected profiles was employed to characterise the basement pattern and architecture, which depicted a horst-graben architecture. The basement structure and architecture have a major control on the distribution of sub-basins, petroleum systems elements and trap styles in the basin. The study demonstrates the robust application of high-resolution aeromagnetic data in basin-wide mapping of regional subsurface geological features, basement architecture and determination of sedimentary thickness in a frontier basin.

The renewed quest to boost Nigeria’s dwindling reserves through aggressive search for oil and gas deposits in Cretaceous sedimentary basins has re-ignited the need to re-evaluate the hydrocarbon potentials of the Dahomey Basin. Aeromagnetic data are a low-cost geophysical tool deployed in mapping regional basement structures and determination of basement depths and sedimentary thickness in frontier basin exploration. In this study, high-resolution aeromagnetic (HRAM) data covering the Dahomey Basin Nigeria have been interpreted to map the basement structural configuration and to identify mini-basins favorable for hydrocarbon prospectivity. The total magnetic intensity grid was reduced to the equator (RTE) and edge detection filters including first vertical derivative (FVD), total horizontal derivative (THDR), tilt derivative (TDR) and total horizontal derivative of upward continuation (THDR_UC)) were applied to the RTE grid to locate the edges and contacts of geological structures in the basin. Depth to magnetic sources were estimated using the source parameter imaging (SPI) method. Data interpretation results revealed shallow and deep-seated linear features trending in the NNE-SSW, NE-SW, NW-SE and WNW-ESE directions. The SPI map showed a rugged basement topography which depicted a horst-graben architecture on 2D forward models along some selected profiles. Two mini-basins ranging in basement depths between 4.5 – 6.3km were mapped offshore of the study area. It appears the offshore Dahomey Basin holds greater promises for hydrocarbon occurrence due to the presence of thicker succession of sedimentary deposits in the identified mini-basins.

Mineral deposits of significant economic value are abundant in the subsurface of Nigeria, presenting a promising alternative to the nations over dependence on petroleum revenues. This study interprets aeromagnetic data from Share, Kwara State, Nigeria, to delineate subsurface structural features associated with hydrothermal zones, which are key indicators for potential mineralization. The methodologies applied upward continuation, analytic signal, tilt derivative, and first vertical derivative (FVD). These offer insights into subsurface geology that can be broadly applied in geophysical exploration and mineral resource management. The results reveal structural trends predominantly in the NE–SW direction, with some NW–SE alignments, indicative of hydrothermal alterations linked to mineral deposits. The analytical signal map identified amplitude values ranging from 0.004 nT/m to 0.073 nT/m, with low and intermediate magnetic intensities linked to sediment-filled basement rocks and possible limestone and sandstone formations. High-gradient anomalies, 1.280 nT/m to 1.374 nT/m, were attributed to geological contacts, fractures, dykes, and hydrothermal vents. Depth estimates from the source parameter imaging map revealed hydrothermal and structural zones at depths ranging from 287.9 m to 1360.7 m, with deeper sources &gt;1202.1 m indicating tectonic activity and mineralization potential. The FVD and Tilt Derivative maps further highlighted faulted zones, shear structures, and intrusive bodies with intensities between 0.031 nT/m and 0.041 nT/m, suggesting active tectonics. High magnetic anomalies in the central, northeastern, and southeastern regions were identified as prime targets for exploration, indicating magnetite-rich bodies, igneous intrusions, and hydrothermal zones. Integrated exploration strategies combining geophysical, geochemical, and structural data are recommended to refine anomaly delineation, prioritize field validation, and enhance mineralization discovery. These findings establish the Share area as a promising site for regional mineral exploration, supporting Nigeria’s diversification efforts toward sustainable resource development.

In this study, geologic structures, as well as attendant orientations and sediment thickness, in the Nigerian Obudu Complex were delineated using the Centre for Exploration Targeting (CET), and depth determination methods such as source parameter imaging (SPI) and standard Euler deconvolution (SED). The CET, SPI, and SED procedures were applied on the total magnetic intensity data. Also, the enhanced TMI data using analytic signal, first-vertical derivative, total-horizontal derivative, and tilt-angle derivative filters were further subjected to CET operation, with the aim of mapping both subtle and prominent lineaments. In general, mapped geologic structures trends in the NE–SW, NNE–SSW, E–W, and N–S directions. Overall, the dominant geologic structural orientations of NE–SW and NNE–SSW reflect the regional strike orientation. The regional striking of the lineation, which is caused by the Pan-African orogeny and subsequent post-orogenic processes, has an impact on these orientations. The N–S and E–W structural deviations from the main NE–SW and NNE–SSW trends are initiated by the YGS of the post-orogenic events. Overall, these complex geologic structures are probable sites for metallogenic minerals.

An electrical resistivity sounding investigation was carried out within the vicinity of some hand dug wells at Temidire Quarters in Akure, Ondo State, Nigeria.The aim of this study was to compare depth and thickness resolution power of Schlumberger and Wenner arrays.The investigation involved twenty-four vertical electrical soundings (VES) which consisted of twelve Schlumberger array VES and twelve Wenner array VES.The VES results delineated geoelectric layers beneath each VES locations, their layer resistivities, layer thicknesses and depth to aquifer layer(s).Depth to aquifer layer was also determined from static water level measurement and this aided the aquifer layer delineation from VES results.The geoelectric sounding results showed that the study area is dominated by a KH-curve type which consists of top soil, clay/weathered layer, fractured basement and fresh basement.Results from both Schlumberger and Wenner array data were correlated with the static water level measurement; Schlumberger array was found to have higher correlation value than Wenner array.