Magnetic inversion modeling of subsurface geologic structures for mineral deposits mapping in southeastern Nigeria

Yıl 2024, Cilt: 173 Sayı: 173, 85 - 105, 26.04.2024

Ema Abraham , Ayatu Usman Kelvin Chıma George-best Azuoko Iheanyi Ikeazota

https://doi.org/10.19111/bulletinofmre.1267876

Cited By: 3

Öz

Magnetic inversion techniques have been implemented to infer the extension and geometry of magnetic structures and also evaluate its influence on mineralization within Abakaliki and its environs, southeastern Nigeria. The modeling approach considers the techniques of threedimensional (3D) magnetic data inversion, Euler deconvolution, analytic signal inversion, Enhanced Local Wavenumber (ELW) Technique and Particle Swarm Optimization (PSO) to estimate source parameters and compare results. Model solutions were interpreted to represent possible geologic
units with varying trends, housing mineralization within the study region. Results from inversion computation over some active mine locations show subsurface bodies with magnetic susceptibilities
>0.00188 SI. Model results also show structural sources with almost 5.5 km depth extension, stretching 18 km in the EW direction at Ngbo – Ekerigwe location. This could imply significant mineral deposits at the location. Inversion of both magnetic anomaly and analytical signal enabled derivation of the actual subsurface structures in the region, with most of the structures appearing as dykes with depths ranging from 0.2 – 1.8 km at most of the mining sites. Location and depths of some of the modeled intrusions have been corroborated with the active on-site mines. The delineation of mineralization structures by this study would guide systematic exploration in the region.

Anahtar Kelimeler

Magnetic modeling, Aeromagnetic data, Particle Swarm Optimization (PSO), Minerals, Depths

Etik Beyan

We are grateful to the anonymous reviewers, including the editor, whose comments contributed to improve this manuscript. We also acknowledge Dr. Ben Earl Barrowes of Engineer Research and Development Center – U.S. Army for his advice on the programs. Dr. Harish Garg of Thapar Institute of Engineering and Technology, Patiala, School of Mathematics, is also recognized for his advice on the PSO program. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.We would like to declare that total compliance with ethical standards was observed in the preparation of this manuscript and the submitted manuscript posses no conflict of interest between the authors and any other party.

Teşekkür

We are grateful to the anonymous reviewers, including the editor, whose comments contributed to improve this manuscript. We also acknowledge Dr. Ben Earl Barrowes of Engineer Research and Development Center – U.S. Army for his advice on the programs. Dr. Harish Garg of Thapar Institute of Engineering and Technology, Patiala, School of Mathematics, is also recognized for his advice on the PSO program. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.We would like to declare that total compliance with ethical standards was observed in the preparation of this manuscript and the submitted manuscript posses no conflict of interest between the authors and any other party.

Kaynakça

• Abdelrahman, E. M., El-Araby, H. M., El-Araby, T. M., Essa, K. S. 2003. A least-squares minimization approach to depth determination from magnetic data: Pure and Applied Geophysics 160, 1259– 1271.
• Aboud, E., Wameyo, P., Alqahtani, F., Moufti, M. R. 2018. Imaging subsurface northern Rahat Volcanic Field, Madinah city, Saudi Arabia, using Magnetotelluric study. Journal of Applied Geophysics 159, 564 – 572.
• Abraham, E. M., Alile, O. M. 2019. Modelling Subsurface Geologic Structures at Ikogosi Geothermal Field, Southwestern Nigeria, using Gravity, Magnetics, and Seismic Interferometry Techniques. Journal of Geophysics and Engineering 16, 729– 741.
• Abraham, E. M., Itumoh, O., Chukwu, C., Rock, O. 2018. Geothermal Energy Reconnaissance of Southeastern Nigeria from Analysis of Aeromagnetic and Gravity-Data. Pure and Applied Geophysics, 176, 22 – 36.
• Agarwal, B. N. P., Srivastava, S. 2008. FORTRAN codes to implement enhanced-local-wave-number technique to determine location, depth and shape of the causative source using magnetic anomaly. Computer Geosciences 34, 1843–1849.
• Agha, S. O., Arua, A. I. 2014. Integrated-geophysical investigation of sequence of deposition of sedimentary strata in Abakaliki, Nigeria. European Journal of Physical and Agricultural Sciences 2(1) 1-5.
• Anyanwu, G., Mamah, L. 2013. Structural Interpretation of Abakaliki-Ugep using Airborne magnetic and Landsat Thematic Mapper (TM) data. Journal of Natural Science Research 3(13) 20-31
• Benkhelil, J. 1988. Structure Et Evolution Geodynamique De basis Intercontinental De Ca Benoue (Nigeria). Bulletin des Centres de Researches Exploration – Production ELF Aquaintaine 1207, 29.
• Büyüksaraç, A., Reiprich, S., Ates¸ A. 1998. Three- dimensional magnetic model of amphibolite complex in Taskesti area, Mudurnu valley, North- West Turkey. Journal Of The Balkan Geophysical Society 1 (3) 44-52.
• Büyüksaraç, A., Jordanova, D., Ates¸ A., Karloukovski, V. 2005. Interpretation of the Gravity and Magnetic Anomalies of the Cappadocia Region, Central Turkey. Pure Applied Geophysics 162, 2197–2213.
• Clerc, M. 1999. The swarm and the queen: towards a deterministic and adaptive, particle swarm optimization. The Proceedings of International Conference on Evolutionary Computing, Washington 1951–1957.
• Couto, M. A., Aisengart, T., Barbosa, D., Ferreira, R. C. R., Baltazar, O. F., Marinho, M., Cavalcanti, A. D., Araujo, J. C. S. 2017. Magnetization-Vector Inversion, Application in quadrilatero Ferrifero region, MG, Brazil. 15th International Congress of the Brazil Geophysical Society, Rio de Janeiro, Brazil.
• Dobrin, M. B., Savit, C. H. 1988. Introduction to geophysical prospecting. McGraw-Hill Book Co. 867.
• Eshaghzadeh, A., Seyedi Sahebari, S., Dehghanpour, A. 2020. 3D inverse modeling of the gravity field due to a chromite deposit using the Marquardt’s algorithm and forced neural network. Bulletin of the Mineral Research and Exploration 161, 33-47.
• Essa, K. S., Munschy, M. 2019. Gravity data interpretation using the particle swarm optimization method with application to mineral exploration. Journal of Earth System Science 128, 123.
• Essa, K. S., Elhussein, M. 2020. Interpretation of magnetic data through particle swarm optimization: Mineral exploration cases studies. Natural Resources Research 29, 521–537.
• Essa, K. S., Abo-Ezz, E. R. 2021. Potential field data interpretation to detect the parameters of buried geometries by applying a nonlinear least-squares approach. Acta Geodaetica et Geophysica 56, 387– 406.
• Essa, K. S., Nady, A. G., Mostafa, M. S., Elhussein, M. 2018. Implementation of potential field data to depict the structural lineaments of the Sinai Peninsula, Egypt. Journal of African Earth Sciences 147, 43–53.
• Essa, K. S., Mehanee, S., Elhussein, M. 2021. Magnetic Data Profiles Interpretation for Mineralized Buried Structures Identification Applying the Variance Analysis Method. Pure and Applied Geophysics 178, 973–993.
• Eze, L. C., Mamah, L. I. 1985. Electromagnetic, and Ground Magnetic survey, over zones of Lead-Zinc Mineralization in Wanakom (Cross River State). Journal of Earth sciences 7, 749.
• Ezema, P. O., Doris, E. I., Ugwu, G. Z., Abdullahi, U. A. 2014. Hydrocarbon and mineral exploration in Abakaliki, southeastern-Nigeria. The International Journal of Engineering and Science 3(1), 24-30.
• Ford, S. O. 1981. The Economic Mineral Resources of the Benue-Trough. Earth Evolution Sciences 2, 154-163.
• Ganguli, S. S., Singh, S., Das, N., Maurya, D., Pal, S. K., Rama Rao, J. V. 2019. Gravity and magnetic survey in south western part of Cuddapah Basin, India and its implication for shallow crustal architecture and mineralization. Journal of Geological Society of India 93(4) 419-430.
• Ganguli, S. S., Pal, S. K., Kumar, S. K. P. 2021. Insights into the crustal architecture from the analysis of gravity and magnetic data across Salem-Attur Shear Zone (SASZ), Southern Granulite Terrane (SGT), India: an evidence of accretional tectonics. Episodes 44(4) 419 – 422.
• GSNA, 2004. Mineral resources map of Nigeria. Geological- Survey of Nigeria Agency(GSNA).
• Huang, L., Guan, Z. 1998. Discussion on Magnetic- interpretation using the 3-D analytic signal, by Walter R. Roest, Jacob Verhoef, and Mark Pilkingtonç Geophysics 63, 667–670.
• Jain, S. 1988. Total magnetic field reduction—The Pole or Equator? A model study. Canadian Journal of Exploration Geophysics 24 (2) 185–192
• Kennedy, J., Eberhart, R. 1995. Particle-swarm optimization. The Proceedings of IEEE Conference on Neural Networks, Piscataway, NJ 1942–1948.
• Kowalczyk, P., Oldenburg, D., Phillips, N., Nguyen, T. H., Thomson, V. 2010. Acquisition and analysis of the 2007–2009 geosciences BC-airborne data. The Australian, SEG-PESA Airborne, Gravity Workshop.
• Kumar, S., Pal, S. K., Guha, A., Sahoo, S. D., Mukherjee, A. 2020. New insights on Kimberlite emplacement around the Bundelkhand Craton using integrated satellite-based remote sensing, gravity, and magnetic data. Geocarto International 37 (4) 999– 1021.
• Leâo-Santos, M., Li, Y., Moraes, R. 2015. Application of 3D-magnetic amplitude inversion, to iron oxide- copper-gold deposits, at low magnetic latitudes: A case-study from Carajas Mineral Province, Brazil. Geophysics 80(2) B13 – B22.
• Lelievre, P. G. 2003. Forward modeling and inversion of geophysical magnetic data. A master’s thesis submitted to The University of British Columbia.
• Leu, L. K. 1981. Use of reduction-to-the-equator process for magnetic data interpretation. Geophysics 47, 445.
• Li, X. 2003. On the use of different methods for estimating magnetic depth. Leading Edge 22, 1090–1099.
• Li, Y., Sun, J. 2016. Geology-differentiation with uncertainty estimation using inverted-magnetization directions. SEG International Exposition and 86th Annual Meeting 2159
• MacLeod, I. N., Ellis, R. G. 2013. Magnetic vector inversion a simple approach to the challenge of varying direction of rock magnetization. ASEG-PESA 2013. 23rd International Geophysical Conference and Exhibition, 11-14 August 2013-Melbourne, Australia.
• Mahmoodi, O., Smith, R. S., Spicer, B. 2016. Using constrained, inversion of gravity and magnetic- field to produce a 3D litho-prediction model. SEG Inter. Exposition and 86th Annual Meeting 2170– 2174.
• Mehanee, S., Essa, K. S., Diab, Z. E. 2021. Magnetic data interpretation using a new R-parameter imaging method with application to mineral exploration: Natural Resources Research 30, 77–95.
• Melo, A. T., Sun, J., Li, Y. 2015. Geophysical-inversions applied to geological differentiation, and deposit characterization: A case study at an IOCG deposit in Carajás-Mineral-Province, Brazil. 85th Annual International Meeting, SEG, Expanded Abstracts 2012–2016.
• Nabighian, M. N. 1972. The analytic signal of two- dimensional magnetic bodies with polygonal cross-section: its properties and use for automated anomaly interpretation. Geophysics 37, 507–517
• NGA, 2004. GM-SYS Gravity/Magnetic Modeling Software. Northwest Geophysical Associates, Inc., USA.
• Nwachukwu, S. O. 1972. The Tectonic Evolution of the Southern Portion of the Benue Trough, Nigeria. Geological Magazine 109, 411-419.
• Obande, G. E., Lawal, K. M., Ahmed, L. A. 2014. Spectral analysis of aeromagnetic data for geothermal investigation of Wikki Warm Spring, north-east Nigeria. Geothermics 50, 85–90.
• Obarezi, J. E., Nwosu, J. I. 2013. Structural Controls, of Pb- Zn Mineralization, of Enyigba District, Abakaliki, Southeastern Nigeria. Journal of Geology and Mining Research 5 (11) 250-261.
• Ofoegbu, C. O. 1985. A review of the Geology of the Benue Trough. Nigeria, Journal of African Earth Science 3, 283.
• Oha, I. A., Onuoha, K. M. 2013. Contrasting Styles of Pb- Zn-Ba Mineralization in the Lower Benue Trough, Southern Nigeria. A paper presented at the 49th Annual International Conference and Exhibitions of the Nigerian Mining and Geosciences Society (NMGS), Ibadan, March 2013.
• Olade, M. A. 1975. Evolution of Nigeria’s Benue-Trough (Aulacogen): A tectonic model. Geological Magazine 112, 575–581.
• Omada, J. I., Ike, E. C. 1996. On the Economic Appraisal and Genesis of the Barite Mineralization and Saline Springs in the Middle-Benue-Trough. Nigeria. Journal of Mineralogy, Petrology and Economic Geology 91,109-115
• Ovat, O. O. 2015. Obubra yesterday, today, and tomorrow: An assessment of the economic development of a local government area in Cross River State. Nigeria. Journal of Economic and Sustainable Developments 6 (20) 78 – 86.
• Pallero, J. L. G., Fernandez-Martinez, J. L., Bonvalot, S., Fudym, O. 2015. Gravity inversion and uncertainty assessment of basement relief via Particle Swarm Optimization. Journal of Applied Geophysics 116,180–191.
• Pilkington, M. 2009. 3D magnetic data-space inversion with sparseness constraints. Geophysics 74 (1) P.L7-L15.
• Pilkington, M., Bardossy, Z. 2015. DSIM3D: software to perform unconstrained-3D-inversion of magnetic data. Geological Survey of Canada.
• Press, W. H., Teukolsky, S. A., Vetterling, W. T., Flannery, B. P. 1994. Numerical Recipes in FORTRAN. Cambridge University Press, New Delhi.
• Reid, A. B., Thurston, J. B. 2014. The structural index in gravity and magnetic interpretation: Errors, uses, and abuses. Geophysics 79, J61-J66.
• Reid, A. B., Allsop, J. M., Grauser, H., Millet, A. J., Somerton, I. N. 1990. Magnetic interpretation in 3D using Euler-Deconvolution. Geophysics 55, 80-91
• Riedel, S. 2008. Airborne-Based geophysical investigation in Dronning Maud land Antarctica. Dissertation, Christian Albrechts Universitat Zu Kiel, Kiel.
• Roest, W. R., Verhoef, J., Pilkington, M. 1992. Magnetic interpretation using the 3D analytic signal. Geophysics 57 (1) 116-125.
• Sacchi, M. D., Ulrych, T. J. 1995. High-resolution velocity gathers and offset space reconstruction: Geophysics 60, 1169–1177.
• Salem, A., Ravat, D., Smith, R. S., Ushijima, K. 2005. Interpretation of magnetic data using an enhanced local wave number (ELW) method. Geophysics 70, L7–L12.
• Srivardhan, V., Pal, S. K., Vaish, J., Kumar, S., Bharti, A. K., Priyam, P. 2016. Particle swarm optimization inversion of self -potential data for depth estimation of coal ¦res over East Basuria colliery, Jharia coal field, India. Environmental Earth Sciences 75(8) 1-12.
• Srivastava, S., Agarwal, B. N. P. 2010. Inversion of the amplitude of the two-dimensional analytic signal of the magnetic anomaly by the particle swarm optimization technique. Geophysical Journal International 182, 652-662.
• Srivastava, S., Pal, S. K., Rajwardhan, K. 2020. A time- lapse study using Self-Potential and Electrical Resistivity Tomography methods for mapping of old mine working across railway-tracks in a part of Raniganj Coalfield, India. Environmental Earth Sciences 79, 332.
• Stocco, S., Godio, A., Sambuelli, L. 2009. Modelling and compact inversion of magnetic data: A Matlab code. Computers and Geosciences 35, 2111–2118
• Thompson, D. T. 1982. Euldph: A new technique, for making computer-assisted, depth- estimates, from magnetic data, Geophysics 47, 31-37
• Thurston, J. B., Smith, R. S. 1997. Automatic conversion of magnetic data to depth, dip, and susceptibility contrast using the SPITM method. Geophysics 62, 807–813.
• Ugwu, G. Z., Alasi, T. K. 2016. Aeromagnetic Survey for Determining Depth, to Magnetic Source of Abakaliki and Ugep Areas, of the Lower Benue Trough, Nigeria. Engineering and Technology Journal 1(1) 18 – 31.
• Whitehead, N., Musselman, C. 2005. Montaj Gravity/ Magnetic interpretation: Processing, analysis, and visualization system, for 3-D inversion of potential field data, for Oasis montaj v6.1. Geosoft Inc. ON, Canada.
• Yao, C. 2007. Iterative 3-D gravity and magnetic inversion for physical properties. SEG/San Antonio 2007 Annual meeting 805 – 810.