Structural characterization of the Nigerian sector of Benin Basin using geopotential field attributes S. Oladele * , E.A. Ayolabi, C.O. Dublin-Green Department of Geosciences, University of Lagos, Lagos, Nigeria article info Article history: Received 31 December 2015 Received in revised form 23 March 2016 Accepted 24 May 2016 Available online 26 May 2016 Keywords: Geopotential attributes Structures Benin Basin Aeromagnetics Sediment thickness abstract The structural dispositions of the Nigerian sector of the Benin Basin have been investigated using at- tributes of geomagnetic and gravimetric fields. Aeromagnetic anomalies were reduced to the equator to improve the correspondence of the anomalies with the causative bodies. The residual, upward continued, tilt and horizontal derivatives, and pseudogravity attributes and forward models of both geomagnetic and gravimetric anomalies were computed to accentuate geological features including shallow and regional faults, fracture network, basement block pattern and depth to magnetic basement. Three gen- erations of sinistral faults were identified. The oldest generation of faults (F1) is the NE-SW trend cor- responding to the oceanic fracture zones trend. The F1 is truncated by the second generation of faults (F2) with E-W trends. The third generation of faults (F3) assumes NW-SE trend and is offset by F2. Shallow and deep regional faults and fractures envisaged to play major role in migration and entrapment of hydrocarbons and localization of mineral resources in this area were imaged. The coastline, Lagos and Lekki Lagoons surface geometry showed high degree of similarity with their underlying basement block pattern, thus implying that these surface features are structurally controlled. The basement morphology is not flat but of horst and graben architecture in which sediment thickness attained about 4 km within the graben. Hence, the graben has significant hydrocarbon potential. This study has shown the capa- bilities of geopotential field attributes in providing information about the structural architecture of frontier basin. Such knowledge will aid the understanding of the geology of the basin and its resources. © 2016 Elsevier Ltd. All rights reserved. 1. Introduction The Nigerian portion of the Benin Basin (Fig. 1), occupying the southwestern part of Nigeria between longitude 2  30 0 (320,000 mE) and 4  30 0 E (580,000 mE), and latitude 6  00 0 (665,000 mN) and 7  00 0 N (775,000 mN), is considered to be one of the frontier basins in oil exploration. This Basin has been a subject of renewed exploration interests due to rejuvenated interest of the Nigerian government in increasing her crude reserve through exploration of frontier basins. The study of basin structures is one of the important economic applications of magnetic method in oil and gas explo- ration. Local variations in magnetic properties of crustal rocks cause anomalies in the earth’s magnetic field; and geologic structures (like faults and folds) may produce small magnetic fields that distort the main magnetic field of the earth. Because basin fill typically has a much lower susceptibility than the crystalline basement (Nabighian et al., 2005), and basements commonly exhibit variation in susceptibility; it is commonly possible to esti- mate the depth to basement and quantitatively map basement structures (Prieto and Morton, 2003). Likewise, gravity method has been used for many years to map the geometry and features of remote basins (Jacques et al., 2003) where density contrast exists. Earlier work in the study area (Coker and Ejedawe, 1987) ascribed a low petroleum potential to the Benin Basin but recent exploratory efforts in the basin have resulted into discovery of commercial oil in Aje field offshore Lagos, thus establishing the fact that the basin is a potential petroleum province (Brownfield and Charpentier, 2006). Despite magnetic and gravity methods being prime tools for assessing the structural prospects of any frontier basin, surprisingly basin-wide geopotential study was not carried out over this basin from the petroleum exploration point of view. Previous geo- potential attempts to study the basin were commonly restricted to a section of the basin (e.g Opara et al., 2012; Osinowo and Olayinka, 2013; Oladele and Ayolabi, 2014). In this study, attributes of high resolution aeromagnetic data and coarse satellite derived gravity * Corresponding author. E-mail address: soladele@unilag.edu.ng (S. Oladele). Contents lists available at ScienceDirect Journal of African Earth Sciences journal homepage: www.elsevier.com/locate/jafrearsci http://dx.doi.org/10.1016/j.jafrearsci.2016.05.021 1464-343X/© 2016 Elsevier Ltd. All rights reserved. Journal of African Earth Sciences 121 (2016) 200e209