2-dimensional electrical resistivity tomography (ERT), microbial and geochemical methods were use... more 2-dimensional electrical resistivity tomography (ERT), microbial and geochemical methods were used as a tool in detection of groundwater contamination at Akure North municipal solid waste–disposal site in Igbatoro road, South Western Nigeria. Six (6) 2D resistivity profiles both around the perimeter and inside the dump were investigated with maximum length of 300 m. Results of the resistivity tomography delineated the leachate plume as low resistivity zones (6 - 33 ohm - m). Results of the physico-chemical analysis of water samples from existing borehole wells reported elevation in concentration of the measured parameters indicating contamination of the groundwater as a result of solid waste leachate accumulation, consequently, complimenting the geophysical data. The microbial analysis of water samples in the same borehole wells reported the presence of some toxic microorganisms such as staphylococcus sp, escherichia coli, streptococcus sp, basillus sp, clostridium sp, mycobacterium...
The IGRF filtered Aeromagnetic data over Iwo, southwestern part of Nigeria within the basement co... more The IGRF filtered Aeromagnetic data over Iwo, southwestern part of Nigeria within the basement complex was subjected to reduction to magnetic equator filtering, residual filtering, upward and downward continuation filtering, automatic gain control filtering, tilt angle derivative, second vertical derivative, analytical signal and Euler deconvolution. This reveals the geologic information such as structural trend. Based on the result of the total magnetic intensity map, reduction to equator map, analytical signal map and residual magnetic intensity map, it can be concluded that; The rocks in the study area have a trend of approximately northeast-southwest direction as seen on the upward continuation map. Most of the delineated lineaments found within the study area strike mostly in NNE-SSW, NE-SW and NW-SE with minor trend of E-W and ENE-WSW direction. Structural lineament orientation suggested that they were products of Pan-African orogeny (NE-SW, NW-SE and NNE-SSW trends) and pre-P...
Earth’s Crust and Its Evolution - From Pangea to the Present Continents
The geodynamics of the Southwestern Nigeria Precambrian Basement Rocks were studied with aim of u... more The geodynamics of the Southwestern Nigeria Precambrian Basement Rocks were studied with aim of understanding the evolution of rocks globally. Magnetic carriers of Precambrian Basement rocks samples collected from 110 locations were prepared for rock magnetism, optical microscopy and Scanning Electron Microscopy (SEM). The Natural Remanent Magnetisation (NRM) of the remagnetised and unmagnetised rocks are strong (0.3–1.7 A/m -< 0.5 A/m) showed northwesterly direction with moderate inclination and weak NRM with westerly shallow direction respectively. Primary and secondary NRMs are carried by maghemite, and the remagnetised and unmagnetised rocks revealed a higher coercivity for alternating field demagnetisation (<20 mT – < 10 mT median destructive field). Optical microscopy revealed maghemite, poor titanomagnetite, titanomaghemite lamellae >30 pm and finer maghemite/magnetite grains finer than 10 pm. X-ray Diffratometry (XRD) and SEM results implied NW remanence in the r...
This study entails the detailed analyses of high-resolution gravimetry dataset using enhancement ... more This study entails the detailed analyses of high-resolution gravimetry dataset using enhancement techniques for characterising and delineating the locations, edges/boundaries, trends, and depths of lithostructural features around Precambrian basement complex of Igabi region, Northwestern Nigeria with a view of evaluating the structural architectures that harbor mineralization in the study area. The analyzed results of the bouguer anomaly and residual maps of study area showed the distribution of the gravity anomalies and magnitudes of the concealed structures based on the observed low to very high gravity anomalies. Bouguer anomalies around Igabi area ranged between -67.77 to -53.34 mGal reflecting the density variations within bedrock. The upward continued bouguer anomaly maps at distance 500 m, 1 km, 2 km, 3 km, and 4 km revealed the variations of the deep-seated basement rocks, the structures and the concealed anomalous bodies with general regional trends in NW-SE, E-W, and NE-SW...
Integrated well dataset and seismics delineated the PGS field onshore Niger Delta for reservoir i... more Integrated well dataset and seismics delineated the PGS field onshore Niger Delta for reservoir identification. Gamma ray, resistivity, Neutron and density Logs identified four lithologies: sandstone, shaly sandstone, shaly sand and shale. They consist of sand-shale intercalation with the traces of shale sometimes found within the sand Formation. Petrophysical parameters of the reservoirs showed varying degree of lower density, low gamma ray, high porosity and resistivity response with prolific hydrocarbon reservoir G due to its shale volume and the clean sand mapped as a probable hydrocarbon reservoir. 3D seismic data located both seismic scale and sub-seismic scale structural and stratigraphic elements. Risk reduction in dry hole drilling due fault missing in conventional seismic attribute analysis and interpretation, have to be integrated into the Oil companies standard practice.
Igabi aerogravity dataset was interpreted to delineate litho-structural architectures that could ... more Igabi aerogravity dataset was interpreted to delineate litho-structural architectures that could favour the exploitation of potential economic minerals. The distribution of the gravity anomalies over the area ranged from-67.77 to-53.34 mGal. The upward continued bouguer anomaly maps at distance 500 m, 1 km, 2 km, 3 km, and 4 km revealed the variations of anomalous bodies with general regional trends in NW-SE, E-W, and NE-SW directions. The superimposed analytic signal indicated low amplitude signals for migmatites, schists, less dense felsic rocks (porphyritic granites) and fractures, while areas of high amplitude signals correlated with biotite granitic and gneissic rocks because of the denser mafic minerals in them. The second vertical derivative and tilt derivative maps revealed the anomaly patterns of shallow basement rocks and near circular closures anomalies that are associated with fractures within the granitic rocks. Spectral analysis suggested depth to gravity sources ranging between 0.3 km and 0.67 km for shallow, 0.90 km and 0.97 km for intermediate and 1.5 km to 1.86 km for deep sources, while Euler solution depths ranged from <1392.3 m to >2059 m. The results, therefore, suggested intense deformation of the basement rocks with tectonic framework suitable for mineralisation.
An integrated geophysical (involving two-dimensional [2D] electrical resistivity) and petrophysic... more An integrated geophysical (involving two-dimensional [2D] electrical resistivity) and petrophysical study was conducted in the Precambrian Crystalline Basement area of Iwaro-oka Akoko, southwestern Nigeria. Five 2D resistivity profiles, both around the perimeters and inside the dump, were investigated with maximum lengths of 100 m. Results of the resistivity imaging delineated the leachate plumes as low-resistivity zones, with values ranging from 3 Ω m to 55 Ω m. The coefficient of permeability ranged from 4.33 × 10
The radiogeochemistry of granite gneisses in Akunu-Akoko (AK) and Ayere (AY) areas of the southwe... more The radiogeochemistry of granite gneisses in Akunu-Akoko (AK) and Ayere (AY) areas of the southwestern Basement Complex of Nigeria was studied using gamma-ray spectrometry and statistical analyses and modelling. This study was aimed at determining the radionuclides concentration in these rocks, as well as alteration scenarios, nature and rates of uranium migration (UM), levels of radiological hazards, and rate of radiogenic heat production (RHP). The interquartile () elemental concentrations for 40 K, 238 U and 232 Th were 0.23&lt;3.75&lt;4.06%; 1.00&lt;4.20&lt;5.40 ppm; and 4.10&lt;16.10&lt;30.20 ppm, respectively, within the minimum and maximum limits of BDL (below detection limit)-5.23%, BDL-9.70 ppm, and 0.40-60.20 ppm. The average activity concentrations of 40 K, 238 U and 232 Th with values of 629.28, 38.58, and 49.96 , respectively, were above their crustal averages in the order of AK3&lt;AK2&lt;AK3&lt;AY3&lt;AY1&lt;AY2. Variability in K-eU-eTh content and alteration in the rocks were affirmed by radioelement ratios and F-parameter. The high radionuclide concentrations could be due to high levels of radioactive-bearing materials, as well as trace and rare earth elements. Low radionuclides concentration in the rocks may have resulted through weathering, metamorphism, and 12-86% outward UM. The absorbed dose rate (ADR) average of 75.09 was within the allowable range, with the Square R prediction rates of 25-92% from the radionuclides. The average radium activity was below the permissible limit of 370 , and the annual effective doses, hazard indices, gamma activity, and activity utilization index were all far below the safe limit of 1. However, gonad equivalent and excess lifetime cancer risk were above their permissible limits. RHP average of 1.89 above the crustal range of 0.8-1.2 may have considerably contributed to the heat flux in the areas. Square R analysis also predicted that 36-86% of RHP rates in the rocks are achievable from the radionuclides. Reduction in the usage of granite gneisses as a sole raw 2 material for constructions is advised due to the increase in radionuclides and some radiological indicators exceeding world allowed limits.
Studies have shown that urban and rural waste management has been a serious problem in Nigeria. T... more Studies have shown that urban and rural waste management has been a serious problem in Nigeria. This work aims at investigating the effect of waste dumps on the groundwater in Odolomi area of Supare Akoko, south-western Nigeria using resistivity sounding method (dipole-dipole) and laboratory water sample analysis. Ten (10) hand-dug well water samples and one (1) spring water sample which serves as a control were collected in the study area and analyzed for hydrogeochemical and microbial characteristics to know their quality and usability. The result of the analysis shows that elements like K, Na, Ca, and Pb are found in excess in the groundwater of the study area and more so, there is presence of micro-organisms like Enterococci, Coliform in the study area. The result of the analysis was then compared to the WHO (2010) standard for drinking water and it is evident that the groundwater is contaminated. The geophysical investigation shows that the area is highly conductive which impli...
Advances in technique development and data interpretation have greatly improved our ability to vi... more Advances in technique development and data interpretation have greatly improved our ability to visualize the subsurface. A Magnetic survey was carried out at Ayegunle Akoko, Supare Akoko and Akungba Akoko in Ondo state Southwestern Nigeria, using a proton precession magnetometer (GSM-19T). A total of ten traverses were established in an SE-NW, E-W, SW/NE direction in the study areas. The acquired magnetic field data were corrected for drift. Qualitative and quantitative interpretations were adopted to obtain negative peak value and the maximum positive peak value. The contour maps, 3-D surface map and the 1-grid vector map present the subsurface image. The survey perimeters of Ayegunle Akoko has a total length of 1800 m at a line spacing of 10 m and a breadth of 45 m at 5 m spacing; Supare Akoko has a total length of 1500 m at a line spacing of 10 m while Akungba Akoko has a total length of 1700 m at a line spacing of 10 m. The whole area was characterized by complete varying negati...
Potential-field data of Ibadan sheet was processed to interpret the subsurface geology and estima... more Potential-field data of Ibadan sheet was processed to interpret the subsurface geology and estimate the depth to basement sources in order to evaluate and deduce structural lineaments, basement configuration trends. Aeromagnetic data were acquired, filtered, inverted, and enhanced using appropriate software packages to generate a model of the subsurface topography. The Butterwort ANALYSIS 53(264), December 1, 2017 Discovery ISSN 2278–5469 EISSN 2278–5450
2-dimensional electrical resistivity tomography (ERT), microbial and geochemical methods were use... more 2-dimensional electrical resistivity tomography (ERT), microbial and geochemical methods were used as a tool in detection of groundwater contamination at Akure North municipal solid waste–disposal site in Igbatoro road, South Western Nigeria. Six (6) 2D resistivity profiles both around the perimeter and inside the dump were investigated with maximum length of 300 m. Results of the resistivity tomography delineated the leachate plume as low resistivity zones (6 - 33 ohm - m). Results of the physico-chemical analysis of water samples from existing borehole wells reported elevation in concentration of the measured parameters indicating contamination of the groundwater as a result of solid waste leachate accumulation, consequently, complimenting the geophysical data. The microbial analysis of water samples in the same borehole wells reported the presence of some toxic microorganisms such as staphylococcus sp, escherichia coli, streptococcus sp, basillus sp, clostridium sp, mycobacterium...
Journal of Petroleum Exploration and Production Technology
Aeromagnetic and vertical electrical sounding around Ijano, southwestern Nigeria, was investigate... more Aeromagnetic and vertical electrical sounding around Ijano, southwestern Nigeria, was investigated for groundwater potential. Aeromagnetic dataset and vertical electrical sounding were acquired and used to investigate the study area. Oasis Montaj, Microsoft Excel and Arc GIS were used to present the results in maps, images and profiles. In order to map out the geological structures of the study area, magnetic image enhancing filters applied to the total magnetic intensity using Geosoft (Oasis Montaj) are reduction to equator, vertical derivative, total horizontal derivative and upward continuation. These filters helped define the lithological boundaries, geological structures, faults, folds and contacts. The lineament of aeromagnetic map was generated from derived field intensity gradients and solutions of Euler deconvolution carried out on the aeromagnetic data using structural index of 0.5 and 1. The processed image shows the lineaments trends majorly towards NE–SW directions. Fro...
High resolution aeromagnetic dataset of Abakiliki (sheet 303 SW) was used for the characterizatio... more High resolution aeromagnetic dataset of Abakiliki (sheet 303 SW) was used for the characterization of the subsurface lithostructural features in part of the Lower Benue Trough, Nigeria. This study was necessitated for mapping and delineating hydrocarbon prospecting zones, in order to boost the Nation's economy. The aeromagnetic data were subjected to several forms of filtering, reductions, and enhancement techniques for both qualitative and quantitative interpretations. The result of the reduction to equator-total magnetic intensity (RTE-TMI) revealed the magnetic intensity of subsurface rocks ranging from 34.14nT to 61.40nT. These range of magnetic intensity values characterized the rocks in the area as shale and Limestone within the Asu River Group, Awgu shale, Eze-AKu shale and Nkporo shale. The upward continued RTE-TMI data to 500m, 1 km, 2 km, 3 km, 7 km and 10 km revealed regional trends of these rocks and structure thin-out with measure depth continuation. The second vertical derivative (SVD), Tilt-angle derivative (TDR) and Analytical signal (AS) revealed three (3) major faults; F1-F 1 1, F2-F 1 2 and F3-F 1 3 in NE-SW, ENE-WSW and NW-SE directions respectively. The depth to top of magnetic source were revealed by the radially averaged power spectrum (RAPS) and Euler deconvolution as 27m and 2.64km for shallower and deeper sources respectively. This study has demonstrated the efficiency of aeromagnetic methods, with their improved techniques as tools for regional mapping of lithologies and structures that may host important minerals and/or aid hydrocarbon accumulation and their probable depths.
Integrated geophysical techniques were applied for groundwater exploration in a typical southwest... more Integrated geophysical techniques were applied for groundwater exploration in a typical southwestern Nigeria basement terrain. EM-3D was primarily used to map out the precise subsurface conductive zones before adopting the recommended sounding locations with aid of Vertical Electrical Sounding (VES) technique. Hydraulic parameters were also estimated and plotted. Twenty Electromagnetic (EM) horizontal profiling and Schlumberger methods were conducted in E-W and N-S direction across the site. The points where the inflection of the raw real intersects the positive peak of the filtered real are diagnostic of major conductive zones suspected to be faults/fractures. Possible groundwater flow paths that identified as conductive zones were used in picking locations for VES deep sounding. The VES conducted on the conductive zones, which are labelled V 1, V 2, V 3 and V 4 were characterised by good aquifer resistivity values with relatively thick overburden, which are the major factors in determining the groundwater potential of an area in a typical basement complex, while those carried out on the non-conductive zones labelled V 5 and V 6 were characterised by poor indication to groundwater potential of the area.
Exploration of structural dynamics using high resolution aeromagnetic dataset of Abakiliki part o... more Exploration of structural dynamics using high resolution aeromagnetic dataset of Abakiliki part of the Lower Benue Trough, Nigeria; was deployed for mapping and delineating hydrocarbon prospecting zones, in order to boost the Nation's economy. The aeromagnetic data were subjected to several forms of filtering, reductions, and enhancement techniques for both qualitative and quantitative interpretations. The result of the reduction to equator-total magnetic intensity (RTE-TMI) revealed the magnetic intensity of subsurface rocks ranging from 34.14nT to 61.40nT. This range of magnetic anomalies intensity values extends to the sedimentary covers of Asu River Group, Awgu shale, Eze-AKu shale and Nkporo shale. The second vertical derivative (SVD), Tilt-angle derivative (TDR) and Analytical signal (AS) revealed three (3) major faults; F1-F 1 1, F2-F 1 2 and F3-F 1 3, trending NE-SW, ENE-WSW and NW-SE directions respectively. The depth to top of magnetic source were revealed by the radially averaged power spectrum (RAPS) and Euler deconvolution as 27m-2.64km as well as <250 m-> 2500 m for shallower and deeper sources respectively. This study demonstrated the efficiency of aeromagnetic methods, with their improved techniques as tools for regional mapping of lithologies and structures that may host important minerals and aid hydrocarbon accumulation and their probable depths.
Aeromagnetic data over Akure, Southwestern Nigeria was quantitatively and qualitatively analyzed ... more Aeromagnetic data over Akure, Southwestern Nigeria was quantitatively and qualitatively analyzed to unravel subsurface magnetic anomalies. The analyses made on the IGRF corrected aeromagnetic data acquired was used to estimate depth to anomalous sources using 2-D power spectrum, werner deconvolution and 3-D Euler deconvolution. We gridded and sampled the aeromagnetic dataset; while the spectral analysis transforms the spatial data into frequency domain and provides a relationship between radially average spectrum of the magnetic anomalies and depths to the respective sources. Werner and Euler estimate and examines the shape, type of magnetic field within a window and calculate 3-D source locations based on its structural index. The characteristic nature of the magnetic anomalies as expressed by the profiles that is indicative of the different rock types (charnokite, porphyritic granite, grey gneiss, migmatite). Qualitative interpretation results revealed the following ranges for reduction to equator, upward and downward continuation, analytical signal, vertical derivative as;-418.29nT to 532.35nT,-96.7T to 175.4nT,-544.53nT to 597.70nT,-0.0nT to 2.199nT,-0.1nT to 0.1nT; while the quantitative interpretation results revealed-power spectrum, werner deconvolution and euler deconvolution as: 3.0m to 11.0m, 20.6m to 650m, 166.29m to-323.05m respectively. Location, source and depth of magnetic anomaly have been unraveled.
2-dimensional electrical resistivity tomography (ERT), microbial and geochemical methods were use... more 2-dimensional electrical resistivity tomography (ERT), microbial and geochemical methods were used as a tool in detection of groundwater contamination at Akure North municipal solid waste–disposal site in Igbatoro road, South Western Nigeria. Six (6) 2D resistivity profiles both around the perimeter and inside the dump were investigated with maximum length of 300 m. Results of the resistivity tomography delineated the leachate plume as low resistivity zones (6 - 33 ohm - m). Results of the physico-chemical analysis of water samples from existing borehole wells reported elevation in concentration of the measured parameters indicating contamination of the groundwater as a result of solid waste leachate accumulation, consequently, complimenting the geophysical data. The microbial analysis of water samples in the same borehole wells reported the presence of some toxic microorganisms such as staphylococcus sp, escherichia coli, streptococcus sp, basillus sp, clostridium sp, mycobacterium...
The IGRF filtered Aeromagnetic data over Iwo, southwestern part of Nigeria within the basement co... more The IGRF filtered Aeromagnetic data over Iwo, southwestern part of Nigeria within the basement complex was subjected to reduction to magnetic equator filtering, residual filtering, upward and downward continuation filtering, automatic gain control filtering, tilt angle derivative, second vertical derivative, analytical signal and Euler deconvolution. This reveals the geologic information such as structural trend. Based on the result of the total magnetic intensity map, reduction to equator map, analytical signal map and residual magnetic intensity map, it can be concluded that; The rocks in the study area have a trend of approximately northeast-southwest direction as seen on the upward continuation map. Most of the delineated lineaments found within the study area strike mostly in NNE-SSW, NE-SW and NW-SE with minor trend of E-W and ENE-WSW direction. Structural lineament orientation suggested that they were products of Pan-African orogeny (NE-SW, NW-SE and NNE-SSW trends) and pre-P...
Earth’s Crust and Its Evolution - From Pangea to the Present Continents
The geodynamics of the Southwestern Nigeria Precambrian Basement Rocks were studied with aim of u... more The geodynamics of the Southwestern Nigeria Precambrian Basement Rocks were studied with aim of understanding the evolution of rocks globally. Magnetic carriers of Precambrian Basement rocks samples collected from 110 locations were prepared for rock magnetism, optical microscopy and Scanning Electron Microscopy (SEM). The Natural Remanent Magnetisation (NRM) of the remagnetised and unmagnetised rocks are strong (0.3–1.7 A/m -< 0.5 A/m) showed northwesterly direction with moderate inclination and weak NRM with westerly shallow direction respectively. Primary and secondary NRMs are carried by maghemite, and the remagnetised and unmagnetised rocks revealed a higher coercivity for alternating field demagnetisation (<20 mT – < 10 mT median destructive field). Optical microscopy revealed maghemite, poor titanomagnetite, titanomaghemite lamellae >30 pm and finer maghemite/magnetite grains finer than 10 pm. X-ray Diffratometry (XRD) and SEM results implied NW remanence in the r...
This study entails the detailed analyses of high-resolution gravimetry dataset using enhancement ... more This study entails the detailed analyses of high-resolution gravimetry dataset using enhancement techniques for characterising and delineating the locations, edges/boundaries, trends, and depths of lithostructural features around Precambrian basement complex of Igabi region, Northwestern Nigeria with a view of evaluating the structural architectures that harbor mineralization in the study area. The analyzed results of the bouguer anomaly and residual maps of study area showed the distribution of the gravity anomalies and magnitudes of the concealed structures based on the observed low to very high gravity anomalies. Bouguer anomalies around Igabi area ranged between -67.77 to -53.34 mGal reflecting the density variations within bedrock. The upward continued bouguer anomaly maps at distance 500 m, 1 km, 2 km, 3 km, and 4 km revealed the variations of the deep-seated basement rocks, the structures and the concealed anomalous bodies with general regional trends in NW-SE, E-W, and NE-SW...
Integrated well dataset and seismics delineated the PGS field onshore Niger Delta for reservoir i... more Integrated well dataset and seismics delineated the PGS field onshore Niger Delta for reservoir identification. Gamma ray, resistivity, Neutron and density Logs identified four lithologies: sandstone, shaly sandstone, shaly sand and shale. They consist of sand-shale intercalation with the traces of shale sometimes found within the sand Formation. Petrophysical parameters of the reservoirs showed varying degree of lower density, low gamma ray, high porosity and resistivity response with prolific hydrocarbon reservoir G due to its shale volume and the clean sand mapped as a probable hydrocarbon reservoir. 3D seismic data located both seismic scale and sub-seismic scale structural and stratigraphic elements. Risk reduction in dry hole drilling due fault missing in conventional seismic attribute analysis and interpretation, have to be integrated into the Oil companies standard practice.
Igabi aerogravity dataset was interpreted to delineate litho-structural architectures that could ... more Igabi aerogravity dataset was interpreted to delineate litho-structural architectures that could favour the exploitation of potential economic minerals. The distribution of the gravity anomalies over the area ranged from-67.77 to-53.34 mGal. The upward continued bouguer anomaly maps at distance 500 m, 1 km, 2 km, 3 km, and 4 km revealed the variations of anomalous bodies with general regional trends in NW-SE, E-W, and NE-SW directions. The superimposed analytic signal indicated low amplitude signals for migmatites, schists, less dense felsic rocks (porphyritic granites) and fractures, while areas of high amplitude signals correlated with biotite granitic and gneissic rocks because of the denser mafic minerals in them. The second vertical derivative and tilt derivative maps revealed the anomaly patterns of shallow basement rocks and near circular closures anomalies that are associated with fractures within the granitic rocks. Spectral analysis suggested depth to gravity sources ranging between 0.3 km and 0.67 km for shallow, 0.90 km and 0.97 km for intermediate and 1.5 km to 1.86 km for deep sources, while Euler solution depths ranged from <1392.3 m to >2059 m. The results, therefore, suggested intense deformation of the basement rocks with tectonic framework suitable for mineralisation.
An integrated geophysical (involving two-dimensional [2D] electrical resistivity) and petrophysic... more An integrated geophysical (involving two-dimensional [2D] electrical resistivity) and petrophysical study was conducted in the Precambrian Crystalline Basement area of Iwaro-oka Akoko, southwestern Nigeria. Five 2D resistivity profiles, both around the perimeters and inside the dump, were investigated with maximum lengths of 100 m. Results of the resistivity imaging delineated the leachate plumes as low-resistivity zones, with values ranging from 3 Ω m to 55 Ω m. The coefficient of permeability ranged from 4.33 × 10
The radiogeochemistry of granite gneisses in Akunu-Akoko (AK) and Ayere (AY) areas of the southwe... more The radiogeochemistry of granite gneisses in Akunu-Akoko (AK) and Ayere (AY) areas of the southwestern Basement Complex of Nigeria was studied using gamma-ray spectrometry and statistical analyses and modelling. This study was aimed at determining the radionuclides concentration in these rocks, as well as alteration scenarios, nature and rates of uranium migration (UM), levels of radiological hazards, and rate of radiogenic heat production (RHP). The interquartile () elemental concentrations for 40 K, 238 U and 232 Th were 0.23&lt;3.75&lt;4.06%; 1.00&lt;4.20&lt;5.40 ppm; and 4.10&lt;16.10&lt;30.20 ppm, respectively, within the minimum and maximum limits of BDL (below detection limit)-5.23%, BDL-9.70 ppm, and 0.40-60.20 ppm. The average activity concentrations of 40 K, 238 U and 232 Th with values of 629.28, 38.58, and 49.96 , respectively, were above their crustal averages in the order of AK3&lt;AK2&lt;AK3&lt;AY3&lt;AY1&lt;AY2. Variability in K-eU-eTh content and alteration in the rocks were affirmed by radioelement ratios and F-parameter. The high radionuclide concentrations could be due to high levels of radioactive-bearing materials, as well as trace and rare earth elements. Low radionuclides concentration in the rocks may have resulted through weathering, metamorphism, and 12-86% outward UM. The absorbed dose rate (ADR) average of 75.09 was within the allowable range, with the Square R prediction rates of 25-92% from the radionuclides. The average radium activity was below the permissible limit of 370 , and the annual effective doses, hazard indices, gamma activity, and activity utilization index were all far below the safe limit of 1. However, gonad equivalent and excess lifetime cancer risk were above their permissible limits. RHP average of 1.89 above the crustal range of 0.8-1.2 may have considerably contributed to the heat flux in the areas. Square R analysis also predicted that 36-86% of RHP rates in the rocks are achievable from the radionuclides. Reduction in the usage of granite gneisses as a sole raw 2 material for constructions is advised due to the increase in radionuclides and some radiological indicators exceeding world allowed limits.
Studies have shown that urban and rural waste management has been a serious problem in Nigeria. T... more Studies have shown that urban and rural waste management has been a serious problem in Nigeria. This work aims at investigating the effect of waste dumps on the groundwater in Odolomi area of Supare Akoko, south-western Nigeria using resistivity sounding method (dipole-dipole) and laboratory water sample analysis. Ten (10) hand-dug well water samples and one (1) spring water sample which serves as a control were collected in the study area and analyzed for hydrogeochemical and microbial characteristics to know their quality and usability. The result of the analysis shows that elements like K, Na, Ca, and Pb are found in excess in the groundwater of the study area and more so, there is presence of micro-organisms like Enterococci, Coliform in the study area. The result of the analysis was then compared to the WHO (2010) standard for drinking water and it is evident that the groundwater is contaminated. The geophysical investigation shows that the area is highly conductive which impli...
Advances in technique development and data interpretation have greatly improved our ability to vi... more Advances in technique development and data interpretation have greatly improved our ability to visualize the subsurface. A Magnetic survey was carried out at Ayegunle Akoko, Supare Akoko and Akungba Akoko in Ondo state Southwestern Nigeria, using a proton precession magnetometer (GSM-19T). A total of ten traverses were established in an SE-NW, E-W, SW/NE direction in the study areas. The acquired magnetic field data were corrected for drift. Qualitative and quantitative interpretations were adopted to obtain negative peak value and the maximum positive peak value. The contour maps, 3-D surface map and the 1-grid vector map present the subsurface image. The survey perimeters of Ayegunle Akoko has a total length of 1800 m at a line spacing of 10 m and a breadth of 45 m at 5 m spacing; Supare Akoko has a total length of 1500 m at a line spacing of 10 m while Akungba Akoko has a total length of 1700 m at a line spacing of 10 m. The whole area was characterized by complete varying negati...
Potential-field data of Ibadan sheet was processed to interpret the subsurface geology and estima... more Potential-field data of Ibadan sheet was processed to interpret the subsurface geology and estimate the depth to basement sources in order to evaluate and deduce structural lineaments, basement configuration trends. Aeromagnetic data were acquired, filtered, inverted, and enhanced using appropriate software packages to generate a model of the subsurface topography. The Butterwort ANALYSIS 53(264), December 1, 2017 Discovery ISSN 2278–5469 EISSN 2278–5450
2-dimensional electrical resistivity tomography (ERT), microbial and geochemical methods were use... more 2-dimensional electrical resistivity tomography (ERT), microbial and geochemical methods were used as a tool in detection of groundwater contamination at Akure North municipal solid waste–disposal site in Igbatoro road, South Western Nigeria. Six (6) 2D resistivity profiles both around the perimeter and inside the dump were investigated with maximum length of 300 m. Results of the resistivity tomography delineated the leachate plume as low resistivity zones (6 - 33 ohm - m). Results of the physico-chemical analysis of water samples from existing borehole wells reported elevation in concentration of the measured parameters indicating contamination of the groundwater as a result of solid waste leachate accumulation, consequently, complimenting the geophysical data. The microbial analysis of water samples in the same borehole wells reported the presence of some toxic microorganisms such as staphylococcus sp, escherichia coli, streptococcus sp, basillus sp, clostridium sp, mycobacterium...
Journal of Petroleum Exploration and Production Technology
Aeromagnetic and vertical electrical sounding around Ijano, southwestern Nigeria, was investigate... more Aeromagnetic and vertical electrical sounding around Ijano, southwestern Nigeria, was investigated for groundwater potential. Aeromagnetic dataset and vertical electrical sounding were acquired and used to investigate the study area. Oasis Montaj, Microsoft Excel and Arc GIS were used to present the results in maps, images and profiles. In order to map out the geological structures of the study area, magnetic image enhancing filters applied to the total magnetic intensity using Geosoft (Oasis Montaj) are reduction to equator, vertical derivative, total horizontal derivative and upward continuation. These filters helped define the lithological boundaries, geological structures, faults, folds and contacts. The lineament of aeromagnetic map was generated from derived field intensity gradients and solutions of Euler deconvolution carried out on the aeromagnetic data using structural index of 0.5 and 1. The processed image shows the lineaments trends majorly towards NE–SW directions. Fro...
High resolution aeromagnetic dataset of Abakiliki (sheet 303 SW) was used for the characterizatio... more High resolution aeromagnetic dataset of Abakiliki (sheet 303 SW) was used for the characterization of the subsurface lithostructural features in part of the Lower Benue Trough, Nigeria. This study was necessitated for mapping and delineating hydrocarbon prospecting zones, in order to boost the Nation's economy. The aeromagnetic data were subjected to several forms of filtering, reductions, and enhancement techniques for both qualitative and quantitative interpretations. The result of the reduction to equator-total magnetic intensity (RTE-TMI) revealed the magnetic intensity of subsurface rocks ranging from 34.14nT to 61.40nT. These range of magnetic intensity values characterized the rocks in the area as shale and Limestone within the Asu River Group, Awgu shale, Eze-AKu shale and Nkporo shale. The upward continued RTE-TMI data to 500m, 1 km, 2 km, 3 km, 7 km and 10 km revealed regional trends of these rocks and structure thin-out with measure depth continuation. The second vertical derivative (SVD), Tilt-angle derivative (TDR) and Analytical signal (AS) revealed three (3) major faults; F1-F 1 1, F2-F 1 2 and F3-F 1 3 in NE-SW, ENE-WSW and NW-SE directions respectively. The depth to top of magnetic source were revealed by the radially averaged power spectrum (RAPS) and Euler deconvolution as 27m and 2.64km for shallower and deeper sources respectively. This study has demonstrated the efficiency of aeromagnetic methods, with their improved techniques as tools for regional mapping of lithologies and structures that may host important minerals and/or aid hydrocarbon accumulation and their probable depths.
Integrated geophysical techniques were applied for groundwater exploration in a typical southwest... more Integrated geophysical techniques were applied for groundwater exploration in a typical southwestern Nigeria basement terrain. EM-3D was primarily used to map out the precise subsurface conductive zones before adopting the recommended sounding locations with aid of Vertical Electrical Sounding (VES) technique. Hydraulic parameters were also estimated and plotted. Twenty Electromagnetic (EM) horizontal profiling and Schlumberger methods were conducted in E-W and N-S direction across the site. The points where the inflection of the raw real intersects the positive peak of the filtered real are diagnostic of major conductive zones suspected to be faults/fractures. Possible groundwater flow paths that identified as conductive zones were used in picking locations for VES deep sounding. The VES conducted on the conductive zones, which are labelled V 1, V 2, V 3 and V 4 were characterised by good aquifer resistivity values with relatively thick overburden, which are the major factors in determining the groundwater potential of an area in a typical basement complex, while those carried out on the non-conductive zones labelled V 5 and V 6 were characterised by poor indication to groundwater potential of the area.
Exploration of structural dynamics using high resolution aeromagnetic dataset of Abakiliki part o... more Exploration of structural dynamics using high resolution aeromagnetic dataset of Abakiliki part of the Lower Benue Trough, Nigeria; was deployed for mapping and delineating hydrocarbon prospecting zones, in order to boost the Nation's economy. The aeromagnetic data were subjected to several forms of filtering, reductions, and enhancement techniques for both qualitative and quantitative interpretations. The result of the reduction to equator-total magnetic intensity (RTE-TMI) revealed the magnetic intensity of subsurface rocks ranging from 34.14nT to 61.40nT. This range of magnetic anomalies intensity values extends to the sedimentary covers of Asu River Group, Awgu shale, Eze-AKu shale and Nkporo shale. The second vertical derivative (SVD), Tilt-angle derivative (TDR) and Analytical signal (AS) revealed three (3) major faults; F1-F 1 1, F2-F 1 2 and F3-F 1 3, trending NE-SW, ENE-WSW and NW-SE directions respectively. The depth to top of magnetic source were revealed by the radially averaged power spectrum (RAPS) and Euler deconvolution as 27m-2.64km as well as <250 m-> 2500 m for shallower and deeper sources respectively. This study demonstrated the efficiency of aeromagnetic methods, with their improved techniques as tools for regional mapping of lithologies and structures that may host important minerals and aid hydrocarbon accumulation and their probable depths.
Aeromagnetic data over Akure, Southwestern Nigeria was quantitatively and qualitatively analyzed ... more Aeromagnetic data over Akure, Southwestern Nigeria was quantitatively and qualitatively analyzed to unravel subsurface magnetic anomalies. The analyses made on the IGRF corrected aeromagnetic data acquired was used to estimate depth to anomalous sources using 2-D power spectrum, werner deconvolution and 3-D Euler deconvolution. We gridded and sampled the aeromagnetic dataset; while the spectral analysis transforms the spatial data into frequency domain and provides a relationship between radially average spectrum of the magnetic anomalies and depths to the respective sources. Werner and Euler estimate and examines the shape, type of magnetic field within a window and calculate 3-D source locations based on its structural index. The characteristic nature of the magnetic anomalies as expressed by the profiles that is indicative of the different rock types (charnokite, porphyritic granite, grey gneiss, migmatite). Qualitative interpretation results revealed the following ranges for reduction to equator, upward and downward continuation, analytical signal, vertical derivative as;-418.29nT to 532.35nT,-96.7T to 175.4nT,-544.53nT to 597.70nT,-0.0nT to 2.199nT,-0.1nT to 0.1nT; while the quantitative interpretation results revealed-power spectrum, werner deconvolution and euler deconvolution as: 3.0m to 11.0m, 20.6m to 650m, 166.29m to-323.05m respectively. Location, source and depth of magnetic anomaly have been unraveled.
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