One Dimensional Spectral Analysis and Curie Depth Isotherm of Eastern Chad Basin, Nigeria

One dimensional spectral analysis was applied to aeromagnetic data in order to determine the sedimentary thickness variations, depths to the Curie-temperature isotherm and heat flow measurements within the eastern part of the Nigerian Chad Basin. Two depths sources were interpreted in the area namely; the shallower sources have a mean value of 2.21 km while the deeper ones have an average value of 14.07 km. The result of the analysis shows that depths to the centriod and magnetic bodies (sedimentary thicknesses) range from 11.55 to 18.32 km and 1.65 to 5.12 km respectively. The depth to the Curie temperature isotherm in the area varies between 21.45 km at Mafa-Bama area and 31.52 km at Maiduguri-Gwoza area below sea level. The result also shows that the Curie temperature isotherm within the basin is not a horizontal level surface, but is undulating, and the geothermal gradients associated with it range between 17.45 and 25.64oC/km while the corresponding mantle heat flow is about 46.00 mWm-2 and 67.60 mWm-2. It is good to note that areas of high heat flow correspond to high geothermal gradient within the study area. An inverse relationship exists between calculated Curie depths and heat flow within the study area such that high-heat-flow regions correspond to low Curie depths regions. These results correspond to the depths inferred by extrapolating geothermal gradient and heat-flow values, suggesting that the Curie point depth analysis is a useful tool in estimating regional thermal structure. Based on the computed sedimentary thicknesses and the high geothermal gradient, some parts of the study area have been demarcated for detail hydrocarbon exploration. Keywords: Chad Basin, aeromagnetic data, spectral analysis, Curie point depth, geothermal gradient and Hydrocarbo

Geoelectric Investigation of the Subsurface Structures in Part of Gidan Kwano Campus of the Federal University of Technology, Minna, Nigeria

Geoelectric investigations of the subsurface structures of parts of the Gidan Kwano campus Federal University of Technology (F.U.T) Minna, Nigeria were carried out using vertical electrical soundings technique. The area lies within the Pre-Cambian Basement Complex of Northern Nigeria. This study was carried out with the aim of determining subsurface structures of the area for groundwater potentials and to possibly locate those areas that could be useful for civil engineering work at a very low risk. Thirty-six vertical electrical soundings along six profiles (A-F) were carried out during the geophysical survey. The survey was carried out on grid 500m x500m.  The data obtained were interpreted using computer based program named Zohdy. The result of the interpreted vertical electrical soundings (VES) curves reveals three distinct geo-electric curves types were delineated: K, H and HK-curves with H-type having the most prolific aquifer. The result also shows 3 geo-electric layers which were confirm by borehole lithology. The aquifers in the study area are likely to be found in the fractured basement layers of eastern and southeastern parts of the study area. The civil engineering work can be sited in the northern and southwestern parts of the study area which are the region of shallow basement

Geo-electric Investigation for Groundwater Potential in Awka, Anambra State, Nigeria

Geoelectric investigations for groundwater exploration in Awka area were made using vertical electrical sounding technique. This study is aimed at delineating the aquiferous units in parts of Awka and environs by determining their depths, thicknesses, lateral extent, resistivity of the aquiferous layers and the potential borehole depth at various locations within the area. Twenty vertical electrical soundings were carried out during the geophysical survey using the Schlumberger Array. The data was interpreted using the conventional curve matching and computer iteration method. The results revealed eight different curve types namely; K, H, QH, HK, KH, QK, KQ and KHK-curve types. 65% of all the sounding curves belong to HK and H-types whereas the remaining 35% belongs to other six curve types within the study area. The results also revealed that depths to the water saturated sandstones (aquifer) within the study area range from 30.83m at Kenneth Dike memorial Seconadry School Awka to 225.03m at UNIZIK Science Village. The aquifers are therefore capable of yielding enough water that would serve the immediate environs