Application of aeromagnetic data to map subsurface structural features in Ewekoro, Southwestern Nigeria
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ORIGINAL ARTICLE
Application of aeromagnetic data to map subsurface structural features in Ewekoro, Southwestern Nigeria Kehinde Saheed Ishola1 · Peter Oluwaseyi Akerele1 · Oluwaseun Folarin1 · Lukumon Adeoti1 · Rafiu Bolaji Adegbola2 · Oluwakemi Yemisi Adeogun1 Received: 13 November 2019 / Accepted: 13 May 2020 © Springer Nature Switzerland AG 2020
Abstract In this study, aeromagnetic data were interpreted and analyzed in order to map the subsurface geological structures at Ewekoro, southwestern, Nigeria. To accomplish this goal, some image enhancement techniques were applied to the magnetic data by which concealed subsurface structures were revealed. The total magnetic intensity data were reduced to the magnetic pole using Fourier transformation technique. The results of these filtering techniques were displayed with a number of maps. From the interpreted maps, a number of lineaments majorly trending in NE–SW direction were identified. These lineaments were indications of faults or fractures due to the displacements that might have arisen from tectonic events in the area. The estimated depths from the power spectrum technique suggest the presence of two magnetic sources the shallow and deep sources at depth of 0.02–0.75 km, respectively. The deep source indicates the basement rocks underlying the sedimentary cover in the area. Keywords Basement complex · Magnetic anomalies · Filters · Lineaments · Fault · Power spectrum
Introduction Mapping of geological features such as geological boundaries, contacts, fractures, and faults could be adequately accomplished by deploying geophysical methods. Surveying with geophysical methods is mostly carried out on land, in sea or in air. Among the airborne methods, aeromagnetic
* Kehinde Saheed Ishola [email protected] Peter Oluwaseyi Akerele [email protected] Oluwaseun Folarin [email protected] Lukumon Adeoti [email protected] Rafiu Bolaji Adegbola [email protected] Oluwakemi Yemisi Adeogun [email protected] 1
Department of Geosciences, University of Lagos, Akoka, Lagos, Nigeria
Department of Physics, Lagos State University, Ojo, Nigeria
2
method has proven to have the highest resolution to the detection of features even down to the curie point of the geothermal gradient (Shuey et al. 2009; Nwankwo and Shehu 2015). On the other hand, conventional methods such as drilling tests have become essential tools for subsurface characterization of geological sequences or deposits. However, with the huge finances involved, the drilling methods are still limited in terms of predicting the extent of structural deposits particularly when heterogeneities in the precursor rock and structural complications are not taken into consideration. Over two decades ago, information necessary for the assessment of mineral prospects and estimation of the geometric properties of mineralized structures such as the lateral extent and thickness/depth has been achieved through investigations using geophysical methods supported by geological mapping. Land-b
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