Browsing by Author "Ofoegbu, Charles O."
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Item Open Access Basement morphology of the middle Benue Trough, Nigeria, revealed from analysis of high-resolution aeromagnetic data using grid-based operator methods(Department of Geology and Minning, Nasarawa State University Keffi, 2020-03-05) Anuda, G.K.; Stephenson, Randell A.; Ofoegbu, Charles O.; Obrike, Stephen E.The middle Benue Trough is, the central segment of the Benue Trough, an elongate large intracratonic, Cretaceous to Palaeogene rift basin in Nigeria. This study provides new information about the depth to basement (sediment thickness), basement morphology and tectonics of the middle Benue Trough region through detailed analysis and interpretation of preconditioned high-resolution aeromagnetic data using three grid-based semi- automated depth-estimation methods. Integration of results reveals that the middle Benue Trough region is a moderate to deep, fault bounded rift basin with a maximum sediment thickness (basin fill) of about 6300 m. There are seven deep (> ~2500 m) sedimentary sub-basins and several elongated shallow (< ~1800 m) basement ridges. These sub-basins and basement ridges exhibit dominant NE-SW tectonic trends. Previously mapped magmatic bodies in the axial region of the Trough occur at depths less than about 1000 m. Most of the imaged subsurface features were previously unknown. Subsurface crustal basement structures show trends predominantly NE-SW, ENE-WSW, NNE-SSW and NW-SE and these generally reflect variations in pre-existing crustal basement structural trends in the area, superimposed by the effects of the regional tectonic stress fields responsible for the Trough's tectonic evolution in the Cretaceous – Palaeogene. The implication of the results in regards to hydrocarbon exploration, particularly when combined with published field geological and organic geochemical studies, is that the middle Benue Trough region is more likely to have moderate to low oil prospects and high gas prospects.Item Open Access Estimation of The Structural Pattern and Sedimentary Thickness Over Part Of Anambra Basin, Nigeria Using Aeromagnetic Data(Department of physics, Nasarawa State Univesity Keffi, 2021-02-02) Ikiola, Priscilla E.; Ofoegbu, Charles O.; Uko, Etim D.; Anyanninuola, O.S.Aeromagnetic data acquired over part of the Anambra Basin is analyzed to determine the structural pattern and sedimentary thickness of the basin. The study area is covered by high resolution aeromagnetic data on sheets 301 (Udi), 302 (Nkalagu), 312 (Okigwe) and 313 (Afikpo), and lies between latitudes 5o30'0''-6o30'0'' and longitudes 7o0'0"-8o0'0". The whole area was divided into 25 overlapping blocks of 37.2km2 each and a 2D energy spectral analysis was carried out. Total magnetic intensity data was subjected to filtering and analytical techniques to determine the structural pattern, mineralization potential, depth to the basement, variation in the sedimentary thickness. The structural map generated using the vertical derivatives shows that the major structural orientation of the area is in the ENE-WSW trend and the minor trend is the NW to SE direction widespread all over the area. These structures are as a result of the various near-surface magnetic intrusion within the study area. The spectral analysis result shows two depth layers, the deep and the shallow depth, the depth to magnetic basement for the deep anomalous source ranges from 3.3km to 4.84km with an average depth of 3.99km, while the depth to shallow magnetic sources ranges between 0.46km to 0.67km and an average of 0.56km within the area. The mineralization pattern in this area follows the ENE-WSW direction.Item Open Access Groundwater Investigation Across the Crystalline Basement Rocks in Rogo Area, Kano State Northern Nigeria, Using Resistivity Methods(Department of Geology and Mining, Nasarawa State University Keffi., 2021-03-06) Anuda, G.K.; Obrike, Stephen E.; Ofoegbu, Charles O.One-dimensional (1D) resistivity sounding (VES) and two-dimensional (2D) resistivity imaging methods were employed in groundwater investigation in order to delineate potential aquifers and estimate their transmissivities in Rogo area. Main basement rock units in the area are granites and schistose quartzite rocks of Precambrian to Lower Paleozoic age. Twelve resistivity soundings (VES) were carried out across the area using Schlumberger electrode configuration. The field resistivity sounding data obtained were interpreted with partial curve matching approach and 1D inversion algorithm, IPI2Win. The 2D resistivity imaging survey was conducted along two traverses employing dipole-dipole electrode configuration and the resistivity data acquired were subjected to finite element method modelling using DIPRO inversion algorithm to generate a geologically realistic, 2D subsurface geological model. Three to five geoelectrical layers, as well as weathered bedrock (saprolite) and fractured bedrock (saprock) aquifers were delineated. Seven resistivity sounding curve types (namely H, HA, HK, KH, QH, HKH and KQH) were also identified with the H and HA types being the dominant curve types. Anisotropy coefficient (λ) values ranged from 1.03 to 2.65 with a mean of 1.31. Aquifer transmissivity computed for the weathered bedrock aquifer units varied from 16.01 to 53.3 m /day, with an average value of 30.91 m /day. The study revealed that the Rogo area has moderately high aquifer transmissivity and hence generally exhibits good groundwater potentials.Item Open Access Mineralogical, Geochemical and Geotechnical Characteristics of the Maastrichtian clay Member of the Lafia Formation in Doma and Shabu areas, Middle Benue Trough(Department of Geology and Minning, Nasarawa State University Keffi, 2019-03-06) Obrike, Stephen E.; Maina, B.M.; Ofoegbu, Charles O.The Maastrichtian clay member of the non-fossiliferous Lafia Formation as exposed in Doma and Shabu was investigated to assess its physical and compositional characteristics with a view to establishing its potential use as industrial raw material. The mineralogical determination by X-ray diffraction (XRD) of the clays show prominent peaks of kaolinite as the major clay mineral with diffused mixed layer of illite-smectite-chlorite and mica. Chemical analysis by X-ray Fluorescence reveals a dominance of SiO (54.14 – 58.02), Al O (20.14 – 23.68), Fe O (13.07 – 2 2 3 2 3 + 9.23), TiO2 (1.65 – 2.67) and H O (4.23 – 11.05), while CaO, MgO, K O, Na O, MnO and P O contribute less than 2 2 2 2 5 1% of the total elemental composition. The clays exhibit liquid limits in the range of 41-58%, plasticity index (22 - 36%), linear shrinkage (5.2 - 6.4%), Water Absorption Capacity (6.0 - 7.2%) and Loss on ignition (9.2 - 10.18%). The physical, mineralogical and chemical compositions in comparison with international specifications suggest that these clay deposits could be exploited for paints, cement, refractory ceramics and bricks production.Item Open Access pectral Analysis of Aeromagnetic Data over Some Parts of Central Benue Trough, Nigeria(Department of physics, Nasarawa State Univesity Keffi, 2019-03-28) Ibiene, I.E.; Ofoegbu, Charles O.; Anyanninuola, O.S.; Uko, Etim D.The spectral analysis of the magnetic anomalies over some part of Central Benue Trough, Nigeria, has been carried out in order to determine the magnetic source depths and the variability of basement structures. The aeromagnetic maps of the study area was digitized at two kilometer (2km) intervals and were subjected to multi-regression-least-squares analysis in order to obtain the residual field values. Two- dimensional (2-D) spectral analyses were then carried out to determine the average magnetic source depths. The results of the analysis reveal that the thickness of the sedimentary cover in the area varies between 1.25km and 5.60km; and 0.13km and 1.53km for deeper and shallower sources respectively. The results of this study are indicative of the basement overlain being irregular in shape and is associated with faulted structures