Evaluation of Aeromagnetic Data Over Some Parts of Lower Benue Trough, Nigeria Using Spectral Analysis

C. C Ezeh; O. S Okanya; A.O Usman; O. P Odoh

doi:10.37899/journallamultiapp.v3i1.555

C. C Ezeh Department of Geology And Mining, Enugu State University of Science and Technology, Enugu
O. S Okanya Department of Geology And Mining, Enugu State University of Science and Technology, Enugu
A.O Usman Department of Geology/Geophysics, Alex Ekwueme Federal University, Ndufu-Alike, Ikwo, Ebonyi, Nigeria
O. P Odoh Department of Physics, Michael Okpara University, Umudike, Abia State

DOI: https://doi.org/10.37899/journallamultiapp.v3i1.555

Keywords: Aeromagnetic Data, Spectral Analysis, Basement Topography, Qualitative Interpretation, Quantitative Interpretation

Abstract

We obtained, processed, and interpreted spectral analyses of aeromagnetic data across a portion of the Lower Benue Trough with the goal of estimating the depth to magnetic basement, modeling a conspicuous magnetic anomaly, identifying the basement topography, and evaluating basin configurations. Qualitative interpretation based on visual examination of the total magnetic intensive anomalies map, residual contour map, and first vertical derivative map reveals major faults trending east-west (E-W) and minor faults trending northeast-southwest (NE-SW), which is consistent with the structure of the lower Benue Trough. The western portion of the research region indicates structural change near the towns of Afikpo and Ishiagu, indicating areas of documented intrusive igneous body activity. According to the quantitative interpretation of the aeromagmatic data, the average sedimentary thickness is between (2.3 and 3.2 kilometers) and Quantitative interpretation utilizing spectral analysis identifies two distinct depth sources in the region: shallower sources ranging from 1.09 to 1.6 kilometers in the southern portion of the research area, and deeper sources ranging from 1.61 to 4.90 kilometers in the northern section. Additionally, the research reveals that the depths to the centroid and magnetic bodies (sedimentary thicknesses) vary between 5.02 and 10.65 kilometers and 0.23 and 3.5 kilometers, respectively. It was recommended that a ground magnetic survey be used in conjunction with this work to provide a more conclusive result.

References

Abraham, E. M., Lawal, K. M., Ekwe, A. C., Alile, O., Murana, K. A., & Lawal, A. A. (2014). Spectral analysis of aeromagnetic data for geothermal energy investigation of Ikogosi Warm Spring-Ekiti State, southwestern Nigeria. Geothermal Energy, 2(1), 1-21.

Abraham, E. M., Obande, E. G., Chukwu, M., Chukwu, C. G., & Onwe, M. R. (2015). Estimating depth to the bottom of magnetic sources at Wikki Warm Spring region, northeastern Nigeria, using fractal distribution of sources approach. Turkish Journal of Earth Sciences, 24(5), 494-512.

Akande, S. O., Egenhoff, S. O., Obaje, N. G., Ojo, O. J., Adekeye, O. A., & Erdtmann, B. D. (2012). Hydrocarbon potential of Cretaceous sediments in the Lower and Middle Benue Trough, Nigeria: Insights from new source rock facies evaluation. Journal of African Earth Sciences, 64, 34-47.

Anakwuba, E. K., & Chinwuko, A. I. (2015). One dimensional spectral analysis and Curie depth isotherm of Eastern Chad Basin, Nigeria. Journal of Natural Sciences Research, 5(19), 14-22.

Anthony, C., & Obiora, S. C., (2014) Whole-rock geochemistry of basic and intermediate intrusive rocks in the Ishiagu area: further evidence of anorogenic setting of the Lower Benue rift, southeastern Nigeria; Turkish Journal of Earth Science, 23(4), 427-443.

Anudu, G. K., Onuba, L. N., Onwuemesi, A.G. and Ikpokonte, A.E. (2012). Analysis of aeromagnetic data over Wamba and its adjoining areas in north-central Nigeria. Earth Sci. Res. Journ. 16(1), pp. 25 – 33.

Ayodele, M. O., & Ukaegbu, V. U., (2017) A geologic field report on the geology of Afikpo Basin, Lower Benue Trough, southeastern Nigeria. International Journal of Geography, Geology and Agricultural Research; 1(1), 50-72.

Bhattacharryya, B. K., & Leu, L. K. (1975). Spectral analysis of gravity and Magnetic anomalies due two dimensional structures. Geophysics, (40), pp. 993-1031.

Bhattacharyya, B. K. (1966). Continuous spectrum of the magnetic field anomaly due to a rectangular prismatic body. Geophysics, (31), pp. 121.

Ezepue, M. C. (1984). The Geologic Setting of Lead-Zinc Deposits at Ishiagu, Southeastern Nigeria. Jour. of Afri. Earth Sci.,2, pp. 97-101.

Likkason, O. K. (2007). Angular spectral analysis of aeromagnetic data over the Middle Benue Trough, Nigeria. Journal of Mining and Geology, 43(1), pp. 53 – 62.

Okonkwo, C. C., Onwuemesi, A. G., Anakwuba, E. K., Chinwuko, A. I., Ikumbur B. E. and Usman, A. O., (2012). Aeromagnetic Interpretation over Maiduguri and Environs of Southern Chad Basin, Nigeria. Journal of Earth Sciences and Geotechnical Engineering. 2(3), pp. 77-93.

Okubo, Y.J., Graf, R., Hansen, R.O., Ogawa, K., Tsu, H., (1985). Curie point depth of the Island of Kyushu and surrounding areas. Japan Geophysicics, 53, pp. 481-491.

Petters, S. W. (1978). Stratigraphic evolution of the Benue Trough and its Implications for the upper cretaceous paleogeography of West Africa. Journal of Geology, 86, pp. 311-322.

Ross, H.E., Blakely, R.J., & Zoback, M.D. (2006). Testing the use of aeromagnetic data for the determination of Curie depth in California. Geophysics, 71(5), pp. 51–59.

Saibi, H, Aboud, E. & Azizi, M. (2015). Curie point depth map for Western Afghanistan deduced from the analysis of aeromagnetic data. Proceedings World Geothermal Congress 2015, Melbourne, Australia, pp. 19-25.

Spector, A., & Grant, F. S. (1970). Statistical models for interpretation of aeromagnetic data. Geophysics, 35, pp. 293–302.

Tanaka, A.Y., Okubo, Y. and Matsubayashi, O. (1999). Curie point depth based on spectrum analysis of the magnetic anomaly data in East and Southeast Asia. Tectonophysics, 396, pp. 461-470.

Telford, W. M., Geldart, I. P. and Sheriff, R. E., (1998). Applied Geophysics, Second Edition, Springer, Berlin, 770p.

Usman, A.O., Ezeh, C.C & Chinwuko, A. I (2018). Integration of Aeromagnetic Interpretation and Induced Polarization Methods in Delineating Mineral Deposits and Basement Configuration within Southern Bida Basin, North-West Nigeria. Journal of Geology Geophysics. 7(5) pp. 1-13