Abstract
Airborne geophysical (aeromagnetic and gravity) data of Nsukka area was interpreted qualitatively and quantitatively with the aim of determining the susceptibilities of rock types, depth/mass of the anomalous bodies, possible cause of the anomalies and type of mineralization prevalent in the area. The estimated depths from forward and inverse modeling of aeromagnetic data for profiles 1, 2, 3, 4 and 5 were 1200m, 1644m, 1972m, 2193m and 2285m respectively. The respective susceptibility values were 0.0031, 0.0073, 1.4493, 0.0069 and 0.0016. These indicate dominance of iron rich minerals like limonite, hematite, pyrrhotite, and pyrite and forms lateritic caps on sandstones. SPI depth result ranges from 151.6m minimum (shallow magnetic bodies) to 3082.7 m maximum (deep lying magnetic bodies). Euler depths for the four different structural index (SI = 0.5, 1, 2, 3) ranges from 7.99 to 128.93m which are depths of shallow magnetic sources resulting from lateritic bodies in the outcrops in the study area. From the gravity data interpretation, Euler depth estimation reveals that depth to anomalous bodies ranges from 89.13 to 2296.92m. Density of the causative body obtained from modeling results for profile 1 was 1498kg/m3, which is in the range of clay material and the depth was about 923m. From models 2, 4 and 5, the densities of the causative bodies were 3523, 4127 and 3707kg/m3, while depths to the surface were about 604, 815 and 1893m respectively. These density ranges correspond to that of ironstone. From model three, the density of causative body obtained was 2508kg/m3, located at a depth of about 268m below the surface. This work has shown that Nsukka area is underlain by thick strata of shales, sandstones and ironstones, which together are suitable for ceramic production, and sufficiently thick sediments suitable for hydrocarbon accumulation.
Similar content being viewed by others
References
Adetona, A.A. and Abu, M. (2013) Investigating the structures within the Lower Benue and Upper Anambra Basins, Nigeria, using First Vertical Derivative, Analytical Signal and (CET) Center for Exploration Targeting Plug-in. Earth Sci., v.2(5), pp.104–112.
Agagu, O.K. and Ekweozor, C.M. (1982) Source rock characteristics of Senonian shales in the Anambra Syncline, Southern Nigeria. Jour. Min. Geol., v.19, pp.52–61.
Agagu, O.K., Fayose, E.A. and Petters, S.W. (1986) Stratigraphy and sedimentation in the Senonian Anambra Basin of eastern Nigeria. Jour. Min. Geol., v.22, pp.25–36.
Akaegbobi, I. M. and Schmitt, M. (1998) Organic facies, hydrocarbon source potential and the reconstruction of depositional paleoenvironment of Campano-Maastrichtian Nkporo shale in the Cretaceous Anambra Basin, Nigeria. NAPE Bull., v.13(1), pp.1–19.
Akaegbobi, I.M., Nwachukwu, J.I. and Schmitt, M., (2000) Aromatic hydrocarbon distribution and calculation of oil and gas volumes in post-Santonian shale and coal, Anambra Basin, Nigeria. In: M.R. Mello and B.J. Katz (Eds.), Petroleum systems of south Atlantic margins. AAPG Mem., v.73, pp.233–245.
Akande, S.O. and Erdtmann, B.D. (1998) Burial Metamorphism (Thermal Maturation) in Cretaceous sediments of the Southern Benue Trough and Anambra Basin, Nigeria. AAPG Bull., no.82, pp.191–1206
Briggs, R.P. (1974) Economic geology of Isla de Mona Quadrangle, Puerto Rico. USGS Open File Report, pp.74–226.
Deeba, F. (2001) Seismic analysis of Beani Bazar structure, Surma Basin, Bangladesh. M.Sc. Thesis, Department of Geological Sciences, Jahangirnagar University, Savar, Dhaka, Bangladesh
Dobrin, M.B. and Savit, C.H. (1998) Introduction to Geophysical Prospecting. McGraw Hill Book Co. Inc., New York
Ezema, P.O., Eze, I.D., Ugwu, G.Z. and Abudullahi, U.A. (2014) Hydrocarbon and Mineral Exploration in Abakaliki, Southeastern Nigeria. Internat. Jour. Engr. Sci., v.3, pp.24–30.
Igwesi, I.D. and Umego, N.M. (2013) Interpretation of aeromagnetic anomalies over some parts of lower Benue trough using spectral analysis technique. Internat. Jour. Sci. Tech. Res., v.2(8), pp.153–165.
Nwachukwu, J.I., Odulaja, A.A. and Akinokun, A.A., 1988, Source and reservoir rock potentials of Eze-Aku shale and associated limestones. NAPE Bull., no.3, pp.81–89.
Nwajide, C.S. (1990) Cretaceous sedimentation and paleogeography of the central Benue Trough. In: C.O. Ofoegbu, (Ed.), The Benue Trough structure and evolution. Braunschweig and Wiesbaden, Germany, Vieweg and Sohne Verlag, pp.19-38.
Nwajide, C.S. and Reijers, T.J.A. (1995) Sedimentology and sequence stratigraphy of selected outcrops in the upper cretaceous of lower Tertiary of the Anambra basin. SPDC Exploration Report XPMW. 96007: pp.21–37
Nwajide, C.S. and Reijers, T.J.A. (1997) Sequence architecture of the Campanian Nkporo and Eocene Nanka Formations of the Anambra Basin, Nigeria. NAPE Bull. no.12, pp.75–87
Obaje, N.G. (2009) Geology and Mineral Resources of Nigeria. Lecture Notes in Earth Sciences 120. Springer-Verlag
Ogala, J.E. (2011) Hydrocarbon potential of the upper cretaceous coal and shale units in the Anambra basin, southeastern Nigeria. Petroleum & Coal, v.53(1), pp.35–44.
Onu, N.N., Opara, A.I. and Oparaku, O.I. (2011) Geological interpretation of the aeromagnetic data over the lower Benue trough and some adjoining areas. 47th Annual International Conference of Nigerian Mining and Geoscience Society (NMGS), Programmes and Book of Abstracts, 43
Onwuemesi, A.G. (1997) One dimensional spectral analysis of aeromagnetic anomalies and curie depth isotherm in Anambra basin of Nigeria. Jour. Geodyn., v.23(2), pp.95–107
Onwuemesi, A.G. (1995) Interpretation of magnetic anomalies from the Anambra Basin of southeastern Nigeria. PhD Thesis, Nnamdi Azikiwe University, Awka, Nigeria.
Parasins, D.S. (1986) Principles of applied geophysics, fourth edition. Chapman and Hall, New York.
Petters, S.W. (1978) Stratigraphic Evolution of the Benue Trough and its implications for the Upper Cretaceous Paleogeography of West Africa. Jour. Geol., v.86(3), pp.11–322
Petters, S.W. and Ekweozor, C.M. (1982) Petroleum Geology of Benue Trough and southeastern Chad Basin, Nigeria. AAPG Bull., v.66, pp.1141–1149.
Reid, A. B., Allsop, J.M., Granser, A., Millett, A.J. and Somertom, I.W. (1990) Magnetic interpretation in three dimension using Euler deconvolution. Geophys., v.55, pp.80–91.
Reijers, T.J.A. and Nwajide, C.S. (1988) Geology of the Southern Anambra Basin. Field Course Note 66, Chevron Nigeria Limited.
Reyment, R.A. (1965) Aspects of Geology of Nigeria. Ibadan Univ. Press, Ibadan, Nigeria.
Telford, W.M., Geldart, L.P. and Sheriff, R.E. (1990) Applied Geophysics, second edition. Cambridge Univ. Press, Cambridge.
Thompson, D.T. (1982) EULDPH -new technique for making computer assisted depth estimate of magnetic data. Geophys., v.47, pp.31–37
Ugbor, D.O. and Okeke, F.N. (2010) Geophysical investigation in the lower Benue Trough of Nigeria, using gravity method. Internat. Jour. Phys. Sci., v.5(11), pp.1757–1769.
Ugwu, G.Z. and Ezema, P.O. (2012) Forward and inverse modeling of aeromagnetic anomalies over Abakaliki and Nkalagu areas of the Lower Benue Trough, Nigeria. Internat. Res. Jour. Geol. Min., v.2(8), pp.222–229.
Ugwu, G.Z. Ezema, P.O. and Ezeh, C.C. (2013) Interpretation of aeromagnetic data over Okigwe and Afikpo areas of lower Benue trough, Nigeria. Internat. Res. Jour. Geol. Min., v.3(1), pp.1–8
United States Geological Survey (USGS) (1997) Introduction to Potential Fields. Magnetics.
Wright, J.B., Hastings, D., Jones, W.B. and Williams, H.R. (1985) Geology and Mineral resources of West Africa. George Allen and Urwin, London.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Obiora, D.N., Ossai, M.N., Okeke, F.N. et al. Interpretation of airborne geophysical data of Nsukka area, southeastern Nigeria. J Geol Soc India 88, 654–667 (2016). https://doi.org/10.1007/s12594-016-0532-4
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s12594-016-0532-4