Application of Electrical Resistivity Method for Groundwater Exploration in a Sedimentary Terrain. a Case Study of Ilara-remo, Southwestern Nigeria
A geophysical evaluation using Electrical Resistivity method for groundwater exploration at Ilara-Remo, southwestern Nigeria was carried out. The investigation involved the utilization of Vertical Electrical Sounding (VES) technique with schlumberger electrode array system. The studied area is located within the sedimentary basin (Dahomey basin) of southwestern Nigeria, ferrigenous sandstone was found to be the major rock type in the study area. The data acquired from the ten (10) VES stations were interpreted using the partial curve matching method and computer assisted iteration technique. The VES results of the data revealed three to five layers which include the topsoil, clayey/sandy clay, clayey sand, conglomeratic sandstones and sandstones/wet sands with resistivity values ranging from 133. The sanstones/ wet sands constitute the main aquifer units. From the overall results the studied area can be classified as prolific zones for groundwater development. INTRODUCTION The availability of quality water resources has always been the primary concern of societies in (Semi Arid and Arid region, even in areas of more abundant rainfall, the problem of obtaining an adequate supply of quality water is generally becoming more acute due to ever increasing population and industrialization.
3D Geoelectrical Resistivity Mapping of Tourmaline-Rich Pegmatite in AngwanDoka, Nassarawa State, Northcentral Nigeria
3D geoelectrical resistivity survey was carried out using the Multiple Vertical Electrical Sounding (MVES) along profile lines to determine the extent of mineralized tourmaline-rich pegmatite within a mining site in Angwan Doka community in Kokona Local Government Area, Nassarawa State, Nigeria. A total of 61 out of 90 soundings within a grid area which covered 200m were selected for convenience of modeling. Resistivity data were modeled using a combination of manual curve matching, data inversion and iteration with IP2WIN software, and 3D data modeling using rockworks software. This integrated approach with a resulting 3D model revealed a major trend of the pegmatite in the NE-SW direction which is in line with the overall regional structural strike in the region. The method can therefore be applied extensively for other related subsurface resistivity investigations.
Sand Bodies and Sedimentary Environments: A Review
Knowledge of sand-body morphology may help to solve many practical exploration problems. Knowledge of the environment of deposition is required to predict sand-body morphology most successfully. This paper briefly reviews sand-body nomenclature, discusses the problems of representation by cross sections, comments on currently popular concepts of sedimentary environments, and summarizes in detail what is known of sand-body characteristics in six major environments: alluvial, tidal, turbidite, barrier island, shallow-water marine, and desert eolian. The characteristics of alluvial, tidal, and barrier-island sand bodies are better known than those of turbidite, shallow-water marine, and desert-eolian ones. Nonetheless, there is an obvious lack of systematic, quantitative data on the petrology, texture, sedimentary structures, and internal organization of sand bodies for these six major environments. The problems of sand-body predictions are also briefly summarized. Generally, three types of information are required: depositional environment, regional distribution of sand facies, and paleoslope. Usually prior experience with sandstone bodies of the same facies, preferably in the same basin, is very helpful. Locating a new sandstone body in a basin is usually much more difficult than drilling the first step-out well.