E.C. Chukwu (1), B.N. Ekwueme (2), C.J. Hetherington (3), K. Werts (4), A. C. Ugwu (5), I. Agbi (6)
General Background This study examines the geochemical behavior of granitic rocks in the Shintaku area, a region within the Nigerian Basement Complex where magmatic evolution remains debated due to limited integrated structural–geochemical data. Specific Background Earlier works suggest that Pan-African tectonism produced heterogeneous magmas in southwest Lokoja, yet the mechanisms generating the acidic and intermediate intrusive rocks in this locality are still insufficiently constrained. Knowledge Gap Despite numerous metamorphic studies, the petrogenesis and geochemical pathways of the granitic bodies in southeastern Lokoja have not been comprehensively analyzed using modern analytical techniques. Aims This research investigates magma sources, fractionation trends, and alumina saturation indices to reconstruct the magmatic evolution of the Shintaku granites. Results Major element compositions show enrichment in SiO2, Al2O3, and alkalis, with smooth Harker trends implying fractional crystallization, while rough trends indicate partial melting and magma mixing. The coexistence of metaluminous and peraluminous signatures, along with subalkaline affinities, supports heterogeneous mantle–crust melt interaction. Novelty This study provides the first integrated petrographic and geochemical characterization of the Shintaku granites using XRF, SEM, and LA-ICP-MS datasets. Implications Findings refine the petrogenetic model of southeastern Lokoja and offer a stronger basis for assessing mineralization potential and regional tectonomagmatic evolution.Highlight :
Highlights major compositional variations that reflect the influence of magma fractionation.
Emphasizes evidence of partial melting and magma mixing as drivers of magma heterogeneity.
Confirms the S-type granitoid character linked to peraluminous supracrustal sources.
Keywords : Granitic Rocks, Magmatic Fractionation, Fractional Crystallization, Partial Melting, Magma Mixing
Ajibade, A. C., “Structural and Tectonic Evolution of the Nigerian Basement With Special Reference to NW Nigeria,” International Conference on Proterozoic Geology and Tectonics of High-Grade Terrain, University of Ife, Nigeria, 1988.
Akindele, O. O., “Geology and Geotectonic Setting of the Basement Complex Rocks in Southwestern Nigeria: Implications on Provenance and Evolution,” Earth and Environmental Science, 2011, ISBN 978-953-307-468-9.
Annor, A. E. and Freeth, S. J., “Thermo-Tectonic Evolution of the Basement Complex Around Okene, Nigeria, With Special Reference to the Deformation Mechanism,” Precambrian Research, vol. 28, pp. 269–281, 1985, doi:10.1016/0301-9268(85)90034-8.
Barnes, J. W., Basic Geological Mapping, 4th ed., New York, John Wiley and Sons, 1981.
Bowen, N. L., The Evolution of the Igneous Rocks, Princeton University Press, Princeton, NJ, 1928 (1956 reprint by Dover, New York).
Caen-Vachette, M. and Ekwueme, B. N., “Rb–Sr Ages of the Schists in the Metasedimentary Belts in Southeast Lokoja and Their Implications for the Precambrian Evolution of Central Nigeria,” Journal of African Earth Sciences, vol. 7, no. 1, pp. 127–131, 1988.
Cahen, L., Snelling, N., Delhal, J., and Vail, J. R., The Geology of Africa: The Geochronology and Evolution of Africa, Clarendon (Oxford University Press), New York, 1984, doi:10.1126/science.226.4680.1309.
Chappell, B. W. and White, A. J. R., “Two Contrasting Granite Types: 25 Years Later,” Australian Journal of Earth Sciences, vol. 48, no. 4, pp. 489–499, 2001.
Chukwu, E. C., Granitic Magmatic Processes in the Area Southeast of Lokoja, Southwest Basement Complex, Nigeria, PhD dissertation, University of Calabar, Nigeria, 2025.
Chukwu, E. C., Agibe, A. N., Oshinowo, T. L., and Adaralode, I. M., “The Tectonic Setting of the Rocks Around the Shintaku Area, Southeast of Lokoja, North Central Nigeria,” Journal of Basic Physical Research, vol. 12, no. 1, pp. 30–41, 2024.
Chukwu, E. C., Awoyemi, A. S., and Adejare, B. E., “Structural Attributes and Sequence of Entry of Index Minerals in the Rocks Around the Shintaku Area of Southeastern Lokoja, North Central Nigeria,” Journal of Basic Physical Research, vol. 11, no. 1, pp. 33–44, 2023.
Chukwu, E. C., Agibe, A. N., and Olaoye, S. A., “Aspects of the Petrogenetic Evolution of the Shintaku, Lokoja, North-Central Nigeria,” Minna Journal of Geosciences, vol. 7, pp. 62–76, 2023.
Cox, K. G., Bell, J. D., and Pankhurst, R. J., The Interpretation of the Igneous Rocks, George Allen and Unwin Ltd., London, 1979.
Dada, S. S., “Proterozoic Evolution of Nigeria,” in The Basement Complex of Nigeria and Its Mineral Resources, O. Oshi, Ed., Akin Jinad and Co., Ibadan, 2006, pp. 29–44.
Dada, S. S., “Proterozoic Evolution of the Nigeria–Boborema Province,” West Gondwana: Pre-Cenozoic Correlations Across the South Atlantic Region, Geological Society of London Special Publication, vol. 294, pp. 121–136, 2008, doi:10.1144/SP294.7.
Ejimofor, O. C., Umeji, A. C., and Turaki, U. M., “Petrology and Major Element Geochemistry of the Basement Rocks of the Northern Obudu Area, Eastern Nigeria,” Journal of Mining and Geology, vol. 32, pp. 1–9, 1996.
Ekwueme, B. N., Field Geology and Geological Map Production and Interpretation, Bachudo Science Printing Press, Calabar, 2004.
Ekwueme, B. N., Precambrian Geology and Evolution of the Southeastern Nigerian Basement Complex, University of Calabar Press, Calabar, 2003.
Ekwueme, B. N., “The Petrogenesis of Schists in Southeast Lokoja, Central Nigeria,” Global Journal of Geological Sciences, vol. 1, no. 1, pp. 29–42, 2003, doi:10.4314/gjgs.v1i1.18670.
Ekwueme, B. N., “Rb–Sr Ages and Petrologic Features of Precambrian Rocks From the Oban Massif, Southeastern Nigeria,” Precambrian Research, vol. 47, pp. 271–286, 1990, doi:10.1016/0301-9268(90)90042-0.
Ekwueme, B. N., “Staurolites in Pelitic Schists, Southeast of Lokoja, Nigeria: Composition and Petrologic Implications,” Nigeria Journal of Science, vol. 20, pp. 113–121, 1985.
Ekwueme, B. N., “Regional Metamorphism of Pelitic Rocks in the Southeast of Lokoja, Nigeria,” Nigerian Journal of Mining and Geology, vol. 20, nos. 1–2, pp. 71–77, 1983.
Ekwueme, B. N., “Mineralogy and Petrology of the Metamorphosed Rocks in Southeast Lokoja, Nigeria,” M.Phil. dissertation, University of Nigeria, Nsukka, 1981.
Ekwueme, B. N. and Onyeagocha, A. C., “Plagioclases in Metamorphosed Rocks of Lokoja, Eastern Nigeria,” Journal of African Earth Sciences, vol. 7, nos. 7–8, pp. 887–894, 1988, doi:10.1016/0899-5362(88)90003-6.
Ephraim, B. E., Petrology and Geochemistry of Basement Rocks, Northeast Obudu Bamenda Massif, Southeastern Nigeria, PhD dissertation, University of Calabar, Nigeria, 2005.
Ezepue, M. C. and Odigi, M. I., “Petrology and Geochemistry of Monzodiorites, Granodiorites, and Granites From the Precambrian Terrain Between Kabba and Lokoja, Southwestern Nigeria,” Journal of Mining and Geology, vol. 29, no. 1, pp. 27–39, 1993.
Ferre, E., Deleris, J., Bouchez, J. L., Lar, A. U., and Peucat, J. J., “The Pan-African Reactivation of the Eburnean and Archean Provinces in Nigeria: Structural and Isotopic Data,” Journal of the Geological Society, vol. 153, pp. 719–728, 1996, doi:10.1144/gsjgs.153.5.0719.
Fitches, W. R., Ajibade, A. C., Egbuniwe, I. G., Holt, R. W., and Wright, J. B., “Late Proterozoic Schist Belts and Plutonism in NW Nigeria,” Journal of the Geological Society, vol. 142, pp. 319–337, 1985, doi:10.1144/gsjgs.142.2.039.
Foster, D. A. and Fanning, C. M., “Geochronology of the Northern Idaho Batholiths and the Bitterroot Metamorphic Core Complex: Magmatism Preceding and Contemporaneous With Extension,” Geological Society of America Bulletin, vol. 109, no. 4, pp. 379–394, 1997.
Frost, B. R. and Frost, C. D., “A Geochemical Classification for Feldspathic Igneous Rocks,” Journal of Petrology, vol. 49, no. 11, pp. 1955–1969, 2008.
Frost, B. R., Barnes, C. G., Collins, W. J., Arculus, R. J., Ellis, D. J., and Frost, C. D., “A Geochemical Classification for Granitic Rocks,” Journal of Petrology, vol. 42, no. 11, pp. 2033–2048, 2001.
Harker, A., The Natural History of Igneous Rocks, Macmillan, New York, 1909.
Harper, C. T., Sherrer, G., McCurry, P., and Wright, J. B., “K–Ar Retention Ages From the Pan-African of Northern Nigeria,” Geological Society of America Bulletin, vol. 84, pp. 919–926, 1973.
Haruna, I. V., “Review of the Basement Geology and Mineral Belts of Nigeria,” Journal of Applied Geology and Geophysics, vol. 5, no. 1, pp. 37–45, 2017.
Hubbard, F. H., “Precambrian Crustal Development in Western Nigeria: Indications From the Iwo Region,” Geological Society of America Bulletin, vol. 86, no. 4, pp. 548–554, 1975.
Hyndman, D. W., Petrology of the Igneous and Metamorphic Rocks, 2nd ed., McGraw-Hill, New York, 1985.
Irvine, T. N. and Baragar, W. R. A., “A Guide to the Chemical Classification of Common Volcanic Rocks,” Canadian Journal of Earth Sciences, vol. 8, no. 5, pp. 523–548, 1971.
Kohanpour, F., Gorczy, W., Lindsley, M. D., and Occhipinti, S., “Examining Tectonic Scenarios Using Geodynamic Numerical Modeling: Halls Creek Orogen, Australia,” Gondwana Research, vol. 46, pp. 95–113, 2017.
Kroner, A., Ekwueme, B. N., and Pidgeon, R. T., “The Oldest Rocks in West Africa: SHRIMP Zircon Age for Early Archean Migmatitic Orthogneiss at Kaduna, Northern Nigeria,” Journal of Geology, vol. 109, pp. 399–406, 2001.
Lawal, M., Ayomaya, S. A., Ojero, J. O., Muhammad, A., Yelwa, N. A., Bello, J., and Bello, A., “Integrated Geology and Geochemical Analysis of Eruku Basement Complex, Southwestern Nigeria,” Nigerian Journal of Basic and Applied Sciences, vol. 25, no. 1, pp. 63–72, 2017.
Le Maitre, R. W., Streckeisen, A., Zanettin, B., Le Bas, M. J., Bonin, B., Bateman, P., et al., Igneous Rocks: A Classification and Glossary of Terms, Cambridge University Press, Cambridge, 2002.
Le Maitre, R. W., “The Chemical Variability of Some Common Igneous Rocks,” Journal of Petrology, vol. 17, pp. 589–637, 1976.
MacDonald, G. A., “Composition and Origin of Hawaii Lavas,” Geological Society of America Memoirs, vol. 116, pp. 477–522, 1968.
Metcalfe, S. M., Komorowski, J. C., Robertson, R., Christopher, T. E., Joseph, E. P., and Moretti, R., “Diverse Magma Storage and Major and Volatile Magma Composition Across a Volcanic Arc,” Earth-Science Reviews, vol. 241, pp. 1–32, 2023.
Nuhu, A. T., “A Review of Geotectonic Evolution of the Nigerian Crystalline Basement Complex,” Journal of Science Technology and Education, vol. 10, no. 4, pp. 343–358, 2022.
O’Connor, J. T., “A Classification of Quartz-Rich Igneous Rocks Based on Feldspar Ratios,” US Geological Survey Paper 525-B, pp. 79–91, 1965.
Odeyemi, I. A., “A Review of the Orogenic Events in the Precambrian Basement of Nigeria, West Africa,” Geologische Rundschau, vol. 70, no. 3, pp. 897–909, 1981.
Odigi, M. I., Ezepue, M. C., and Onyeagocha, A. C., “Geochemical Evolution of Pan-African Magmatic Rocks From the Basement Complex Between Okene and Lokoja, Southwestern Nigeria,” Journal of African Earth Sciences, vol. 17, no. 4, pp. 541–553, 1993.
Olarewaju, V. O. and Rahaman, M. A., “Petrology and Geochemistry of the Older Granites From Some Parts of Northern Nigeria,” Nigerian Journal of Mining and Geology, vol. 18, pp. 16–28, 1982.
Ominigbo, O. E., “Evolution of the Nigerian Basement Complex: Current Status and Suggestions for Future Research,” Journal of Mining and Geology, vol. 58, no. 1, pp. 229–236, 2022.
Onyeagocha, A. C. and Ekwueme, B. N., “Temperature–Pressure Distribution Patterns in Metamorphosed Rocks of the Nigerian Basement Complex,” Journal of African Earth Sciences, vol. 11, nos. 1–2, pp. 83–93, 1990.
Pearce, J. A., Harris, N. B. W., and Tindle, A. G., “Trace Element Discrimination Diagrams for the Tectonic Interpretation of Granitic Rocks,” Journal of Petrology, vol. 25, no. 4, pp. 956–983, 1984.
Pitcher, W. S., “Granite Type and Tectonic Environment,” in Mountain Building Processes, Academic Press, London, 1983, pp. 19–40.
Shand, S. J., Eruptive Rocks: Their Genesis, Composition, Classification, and Their Reaction to Ore-Deposits, Thomas Murby and Co., London, 1927.
Streckeisen, A. L., “To Each Plutonic Rock Its Proper Name,” Earth-Science Reviews, vol. 12, pp. 1–33, 1976.
Tijani, M. N., Geology of Nigeria, Springer Nature Switzerland, Cham, 2023.
Ugwu, A. C. and Ekwueme, B. N., “Tracing the Geologic Evolution of Rocks in Ugep Southwest, Southeastern Nigeria,” Global Journal of Geological Sciences, vol. 23, no. 1, pp. 49–59, 2025.
Umeji, A. C., “Petrology and Geochemistry of Monzogranites From Jato Aka and Their Significance to Plutonism in the Pan-African Belts of Nigeria,” Journal of Mining and Geology, vol. 27, no. 1, pp. 115–128, 1991.
Wright, E. P., “Basement Complex,” Geological Survey of Nigeria Bulletin, vol. 32, pp. 12–47, 1971.
Zen, E., “Phase Relations of Peraluminous Granitic Rocks and Their Petrogenetic Implications,” Annual Review of Earth and Planetary Sciences, vol. 16, pp. 21–51, 1998.