Integrated Airborne Potential Field Data Analysis for Mapping the Basement and Structural Architecture of the Lower Benue Trough, Nigeria: Implications for Hydrocarbon Potential
Chigoziem C. Onyekwelu
Department of Physics and Industrial Physics, Nnamdi Azikwe University, Awka, Anambra State, Nigeria.
Gabriel N. Egwuonwu
Department of Physics and Industrial Physics, Nnamdi Azikwe University, Awka, Anambra State, Nigeria.
Izuchukwu I. Obiadi
Department of Applied Geophysics, Nnamdi Azikwe University Awka, Anambra State, Nigeria.
Uzochukwu. C. Omoja
Department of Physics and Industrial Physics, Nnamdi Azikwe University, Awka, Anambra State, Nigeria.
Ejike K. Nnaemeka *
Department of Physics and Industrial Physics, Nnamdi Azikwe University, Awka, Anambra State, Nigeria.
Nneji G. Ezenwa
Department of Physics and Industrial Physics, Nnamdi Azikwe University, Awka, Anambra State, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Airborne magnetic and gravity datasets for the Lower Benue Trough were analysed and interpreted to map concealed subsurface structures within the basin. The basin's hydrocarbon potential was assessed by estimating sedimentary thickness, mapping the basement architecture, and identifying favourable geological structures that may facilitate hydrocarbon migration and entrapment and warrant further detailed investigation. The aeromagnetic and gravity data were processed using regional-residual separation, the first vertical derivative (FVD), and Centre for Exploration Targeting (CET) analysis supported by rose diagrams. Source depths were estimated using Euler deconvolution and Source Parameter Imaging (SPI), while two-dimensional forward modelling of the magnetic and Bouguer anomalies was used to map the subsurface architecture. The FVD maps and rose diagrams revealed major magnetic lineaments and faults trending NE-SW, E-W, and ENE-WSW, whereas the gravity data showed major NE-SW, E-W, NW-SE, and WNW-ESE trends. Minor magnetic trends occurred in the N-S, NW-SE, and NNE-SSW directions, while minor gravity trends occurred in the WNW-SSE, N-S, ENE-WSW, and NNE-SSW directions. Euler deconvolution yielded depths of 717.7-4933.9 m for the magnetic data and 1029-5042 m for the gravity data, whereas SPI yielded depths of 691.7-5121.1 m and 180.3-5518 m, respectively. Two-dimensional forward modelling along the NE-SW profiles yielded depths of 0.8-2.8 km for the magnetic model and 0.4-3.4 km for the gravity model. The undulating basement indicates deep-seated structures that may provide migration pathways and traps for hydrocarbon accumulation. The results therefore indicate sedimentary depths and fault-fracture systems that justify further detailed hydrocarbon exploration studies.
Keywords: Aeromagnetic data, bouguer gravity anomalies, basement architecture, structural lineaments, centre for exploration targeting, source parameter imaging, Euler deconvolution, two-dimensional forward modelling, sedimentary depocentres, hydrocarbon prospectivity