Characterization of the Sulfide Deposits in the Southeastern Nigeria Using VLF Method: Insights from Numerical Modeling and Field Examples
Source: By:D. E. Falebita, O. Afolabi, B. O Soyinka, A. A. Adepelumi
DOI: https://doi.org/10.30564/jgr.v3i1.2809
Abstract:A priori geologic and geophysical information has been used to construc conceptual VLF experiments on conductively and inductively coupled overburden geological models of the lead-zinc (Pb-Zn) mineralization zone found in southeastern Nigeria.This is based on the finite element approach to (1) simulate different geologic situations of overburden occurrence, (2) examine the roles played by overburden in modifying and masking VLF responses of a buried conductor target, and (3) confirm the effectiveness of VLF method in mapping lead-zinc lodes found in sedimentary terrains.The computed theoretical model curves and field examples are expected to serve as guide for VLF anomaly pattern recognition due to overburden thickness, resistivity and width of conductor in similar terrain as the study area.
References:[1] Eze, C. L., Mamah, L. I., and Israel-Cookey, C.,2004. Very low frequency electromagnetic (VLF-EM) response from a lead sulphide lode in the Abakaliki lead/zinc field, Nigeria. Interational Journal of Applied Earth Observation and Geoinformation, 5, 159-163. [2] Victor, O. M., Onwuemesi, A. G., and Aniwetalu, E.U. 2015. Exploration of Lead-Zinc (Pb-Zn) mineralization using very low frequency electromanetic (VLF-EM) in Ishiagu, Ebonyi State. Journal of Geol.Geosci. 4: 214. DOI: https://doi.org/10.4172/2329-6755.1000214 [3] Phillips, W. J., and Richards, W. E., 1975. A study of effectiveness of the VLF method for the location of narrow-mineralised fault zones: Geoexploration, 13,215-226. [4] Warnana, D. D., and Bahri, A. S., 2004. On the use of resistivity and VLF method for profiling underground cave in Ngeposari, Semanu Gunung Kidul. In: Proceedings of the 1st International Seminar of Early Warning System. LPPM-ITS, Surabaya, pp. 33-43. [5] Monteiro-Santos, F. A., Mateus, A., Figueiras, J.,and Gonçalves, M. A. 2006. Mapping groundwater contamination around a landfill facility using the VLF-EM method – a case study. Journal of Applied Geophysics, 60, 115-125. [6] Kaya, M.A., Özürlan, G., and Şengül, E., 2007.Delineation of soil and groundwater contamination using geophysical methods at a waste disposal site in Çanakkale, Turkey. Environmental Monitoring Assessment, 135, 441-446. [7] Al-Tarazi, E., Abu Rajab, J., Al-Naqa, A., and El-Waheidi, M., 2008. Detecting leachate plumes and ground water pollution at Ruseifa municipal landfill utilizing the VLF-EM method. Journal of Applied Geophysics, 65, 121-131. [8] Bahri, A.S., Santoso, D., Kadir, W.G.A., Puradimedja, D. D., Tofan, R. M., and Monteiro-Santos, F.A.,2008. Penerapan metoda Very Low Frequency-vertical Gradient (VLF-EM-vGRAD) untuk memetakan Sungai bawah permukaan di daerah karst. In:Proceedings of the 33rd Pertemuan Ilmiah Tahunan Himpunan Ahli Geofisika Indonesia (PITHAGI), pp.10 - 20. [9] Gürer, A., Bayrak, M., and Gürer, Ö. F., 2009. A VLF survey using current gathering phenomena for tracing buried faults of Fethiye–Burdur fault zone, Turkey.Journal of Applied Geophysics, 68,437-447. [10] Neumann, T., Berner, Z., Stüben, D., Bahri, A. S.,and Jaya, M., 2009. Geowissenschaftliche Bewertung von Karsthöhlen für die asserbewirtschaftung in Gunung Sewu. Wasser Wirtsch. 7-8,31-36. [11] Sharma, S. P., Anbarasu, K., Gupta, S., and Sengupta,A., 2010. Integrated very low- frequency EM, electrical resistivity, and geological studies on the Lanta Khola landslide, North Sikkim, India. Landslides, 7,pp. 43-53. [12] Abbas, A.M., Khalil, M.A., Massoud, U., Monterio-Santos, F., Mesbah, H. A., Lethy, A.,Soliman,M., and Ragab, E. S. A., 2012. The implementation of multi-task geophysical survey to locate leopatra Tomb at Tap-Osiris Magna, Borg El-Arab, Alexandria, Egypt “Phase II”. NRIAG Journal of Astronomy and Geophysics. 1, 1-11. [13] Adelusi, A. O., Ayuk, M. A., and Kayode, J. S., 2014.VLF-EM and VES: an application to groundwater exploration in a Precambrian basement terrain SW Nigeria. Annals of Geophysics, 57, 1, 2014, S0184;DOI: https://doi.org/10.4401/ag-6291. [14] Sungkono, A. S., Bahri, D. D. W., Fernando. A.M.S,and Bagus. J.S., 2014: Fast, simultaneous and robust VLF-EM data denoising and reconstruction via multivariate empirical mode decomposition. Computer and Geoscience, 67: 125-138. [15] Paterson, N. R. and Ronka, V., 1971. Five years of surveying with the very low frequency electromagnetic method. Geoexploration, 9, 7-26. [16] Saydam. A. S., 1981. Very low frequency electromagnetic interpretation using tilt angle and ellipticity measurements. Geophysics, 46, 1594-1605. [17] Jeng, Y., Lin, M-J., Chen, C-S., and Wang, Y-H.2007. Noise reduction and data recovery for a VLFEM survey using a nonlinear decomposition method.Geophysics, vol. 72, No. 5,September-October, pp.F223-F235. [18] Bayrak, M., and Şenel, L., 2012. Two-dimensional resistivity imaging in the Kestelek boron area by VLF and DC resistivity methods. Journal of Applied Geophysics, 82, pp. 1-10. [19] Lowrie, W., and West. G. F., 1965. The effect of conducting overburden on electromagnetic prospecting measurements. Geophysics, 30, 624-632. [20] Lajoie, J. J., and West. G. F., 1976. The electromagnetic response of a conductive inhomogeneity in a layered earth. Geophysics, 41, 1133-1156. [21] Joshi, M. S., Gupta, O. P., Negi, J. G., 1984.Scale-model response of a thin vertical conductor below a conductive, inductive, or laterally inhomogeneous over-burden layer. Geophysics, 49,2159-2165. [22] Babu, V. R, Ram, S. and Sundararajan, N. 2007.Modeling and inversion of magnetic and VLF-EM data with an application to basement fractures: A case study from Raigarh, India. Geophysics, Vol. 72, No. 5;p. B133–b140.10.1190/1.2759921. [23] Akande, S. O., and Mucke, A., 1989. Mineralogical,textural and paragenetic studies of the Lead-ZincCopper mineralization in the lower Benue Trough (Nigeria) and their genetic implications. Journal of African Earth Science, 9, 23-29. [24] Akande, S. O., and Mucke, A., 1993. Coexisting copper sulphides and sulphosalts in the Abakaliki PbZn deposit, lower Benue Trough (Nigeria) and their genetic significance. Mineralogy and Petrology,Volume 47, Issue 2-4, pp 183-192. [25] Benkhelil, J. 1987. Cretaceous deformation, magmatism and metamorphism in the lower Benue Trough,Nigeria. Geological Journal, 22, 467-493. [26] Etim, O.N., Louis, P., and Maurin, J.C., 1988. Interpretation of electrical sounding on the Abakaliki lead–zinc and brine prospects, S.E. Nigeria: Geological and genetic implications. Journal of African Earth Science, 7 (5-6), 743-747. [27] Orajaka, S., and Nwachukwu, S.O., 1968. Combined electromagnetic and geochemical investigations in Ameri lead-zinc area. Journal of Mining Geology, 3,49-52. [28] Olade, M. A and Morton, R. D. 1985. Origin of leadzinc mineralization in the southern Benue trough,Nigeria. Fluid inclusions and trace element studies.Mineral Deposita, 20, 76-80. [29] Mamah, L. I., and Eze, L.C., 1988. Electromagnetic and ground magnetic survey over zones of leadzinc mineralization in Wanakom (Cross River State).Journal of African Earth Science, 7,749-758. [30] Coppo, N., Schnegg, P-A., Defago, M., and GSCB.2006. Mapping a shallow large cave using a high-resolution very low frequency electromagnetic method.Proceedings of the 8th conference on limestone hydrogeology. Neuchatel Switzerland - Web edition,N. Goldscheider, J, Mudry, L. Savoy and F. Zwahlen (Eds), 268 pages. [31] Sinha, A. K., 1990. Interpretation of ground VLFEM data in terms of vertical conductor models.Geoexploration, 26, 213-231. [32] Turberg P., and Müller I., 1992. La méthode inductive VLF-EM pour la prospection hydrogéologique gp" eqpvkpw" fw" oknkgw" Ýuuwtg0" Cppcngu"UekgpvkÝswgu" fg"nÓWpkxgtukvfi" fg Dgucp›qp,Mémoire Hors de Série, nº 11, Cinquième Colloque d´Hydrogéologie en Pays Calcaire et en Milieu Fissuré, Neuchâtel, Suisse, 207-214. [33] Bosch. F. P., and Muller, I., 2001. Continuous gradient VLF measurements: a new possibility for high resolution mapping of karst structures. First Break,19, 343-350. [34] Beamish, D. 1998. "Three-dimensional modelling of VLF data", Journal of Applied Geophysics,vol. 39,pp. 63-76. [35] Sharma. S. P., Biswas, A., and Baranwal. V. C. 2014. Very Low-Frequency Electromagnetic Method: A Shallow Subsurface Investigation Technique for Geophysical Applications. Recent Trends in Modelling of Environmental Contaminants. DOI: https://doi.org/10.1007/978-81-322-1783-1_5 [36] Smith, B. D., and Ward, S. H., 1974. On the computation of polarization ellipse parameters.Geophysics,39, 867-869. [37] Adepelumi, A. A., Yi, M. J., Kim, J. H. and Ako, B. D.2006. Integration of surface geophysical methods for fracture detection in crystalline bedrocks of southwestern Nigeria, Hydrogeology Journal,vol. 14, pp.1284-1306. [38] Saydam. A. S. 1981. Very low-frequency electromagnetic interpretation using tilt angle and ellipticity measurements. Geophysics, Vol. 46 (11), 1508-1618 [39] Kayode, J. S., A.O. Adelusi, M.N.M. Nawawi, M.Bawallah, T.S. and Olowolafe 2016."Geo-electrical investigation of near surface conductive structures suitable for groundwater accumulation in a resistive crystalline basement environment: A case study of Isuada, southwestern Nigeria", Journal of African Earth Sciences, vol. 119, pp. 289-302. [40] Cagniard, L., 1953. Basic theory of the magnetotelluric method of geophysical prospecting.Geophysics,18 (3), 605-635. [41] Kaikkonen, P, 1980. Interpretation nomograms for VLF measurements. Acta. Univ. Ouluensis, A. 92,Phys. 17: 1-48. [42] Karous, M., and Hjelt, S. E., 1983. Linear filtering of VLF dip-angle measurements. Geophysical Prospecting, 31, 782-794. [43] Chung, S. H., Lee, S. H and Kim, J. H., 1990. Depth presentation of VLF-EM data using digital filtering.Geophysical exploration method development series KR-89-2D-2 of Korea institute of energy and resources, 97-115. [44]EM2Dmodel, 2002. EM2DmodelTM version 1.0,Processing and interpretation software for electrical resistivity data. KIGAM,Daejeon, South Korea. [45] Ogilvy, R. D., and Lee, A. C., 1991. Interpretation of VLF-EM in-phase data using current density pseudo sections. Geophysical Prospecting, 39, 567-580. [45] Poddar, M., 1982. Very low-frequency electromagnetic response of a perfectly conducting half-plane in a layered half-space. Geophysics, 47, 1059-1067.