Analysis of Aeromagnetic Data of Ikwo and Environs, Southeastern Nigeria: A Mineral and Hydrocarbon Exploration Guide

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Original Paper

Analysis of Aeromagnetic Data of Ikwo and Environs, Southeastern Nigeria: A Mineral and Hydrocarbon Exploration Guide Charles Chibueze Ugbor,1 Innocent John Arinze,1 and Chidubem Okwudiri Emedo1,2 Received 9 September 2019; accepted 6 February 2020

In the face of impending global energy crises, with demand for minerals and energy surpassing availability, the need to explore relatively frontier areas becomes imperative. In this study, high-resolution airborne magnetic data covering Ikwo and its adjacent areas were utilized to delineate possible mineral-bearing lineaments, determine depth to magnetic causative structures, and assess the sedimentary pile thicknesses with their implication for hydrocarbon and mineral exploration. The total magnetic intensity grid shows an acute change in magnetic intensity values, which reflect the subsurface geological environment. The second vertical derivative image indicates that the western, northwestern and southeastern-most parts of the area are most likely to possess abundant shallow magnetic bodies, which are most probably mineral deposits or igneous intrusive rocks. Ground-based electrical resistivity profiling and induced polarization methods were used to confirm the presence of these shallow bodies. Lineament analysis depicts NE–SW as the principal lineament orientation with minor E–W and N–S trends. The horizontal gradient magnitude revealed two depth models. Deeper bodies, attributed to intra-basement structures were marked as lying between 1.2 km to 4 km whereas shallow intrusive rocks occur within a depth range of 0.2 km to 1 km. The presence of numerous intrusive rocks and a relatively thin sedimentary thickness means that the area is unlikely to favor hydrocarbon accumulation. However, it appears viable and promising for solid mineral exploration. KEY WORDS: Ikwo, Magnetic source, Depth estimation, Anomaly, Basement.

INTRODUCTION In recent years, access to energy has become a global challenge. Owing to growing industrialization, the sustained increase in the economic demand for minerals and energy has not been met with adequate supply (Abraham et al. 2019). In order to bridge the gap in energy supply, natural resources

1

Applied Geophysics Unit, Department of Geology, University of Nigeria, Nsukka 410001, Nigeria. 2 To whom correspondence should be addressed; e-mail: [email protected], [email protected]

exploration in relatively frontier areas becomes necessary. In Nigeria, the Ikwo area presents huge potentials for the exploration and exploitation of some of these vital resources. Several methods have been applied in the investigation of various resources (Lyatsky 2010; Linqi et al. 2017a, b, 2018a, b, 2019a; Ekwok et al. 2019). However, relatively underexplored terrains such as Ikwo and environs require that initial search for mineral and hydrocarbon resources rely mainly on noninvasive geophysical exploration techniques such as the aeromagnetic and electrical methods.

 2020 International Association for Mathematical Geo