ABSTRACT Jebba area southwestern Nigeria forms part of the Nigerian basement complex which lies in the Neoproterozoic PanAfrican mobile belt. It is underlain by several lithological units among which is a polydeformed granitic gneiss. This rock has been dated by LA-ICP-MS yielding a concordant U-Pb zircon age of 2207 ± 20 Ma indicating the crystallization age of the granite protolith. This early Rhyacian age and its affinity with within-plate granites indicates emplacement during crustal extension and rifting presceding the main phase of the Eburnean orogeny. The strong, early, shear fabric, S1, in the rock is interpreted to be also of Paleoproterozoic age i.e. imprinted during the Eburnean orogeny. The Jebba granitic gneiss is thus correlatable with the widely abundant Paleoproterozoic granitic magmatism now represented by many orthogneisses and documented in other parts of southwestern Nigeria, the West African craton, the Borborema Province, the Gurupi Belt, Sao Luis craton and Sao Francisco craton in Brazil.
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C. Okonkwo and V. Ganev, "U-Pb Geochronology of the Jebba Granitic Gneiss and Its Implications for the Paleoproterozoic Evolution of Jebba Area, Southwestern Nigeria," International Journal of Geosciences, Vol. 3 No. 5, 2012, pp. 1065-1073. doi: 10.4236/ijg.2012.35107.
 E, Ferre, G. Gleizeis and R. Caby, “Obliquely Convergent Tectonics and Granite Emplacement in the Trans-Saharan Belt of Eastern Nigeria: A Synthesis,” Precambrian Research, Vol. 114, No. 3, 2002, pp. 199-219.
 A. E. Annor, “U-Pb Zircon Age for Kabba-Okene Granodiorite Gneiss: Implication for Nigeria’s Basement Chronology,” Africa Geoscience Reviews, Vol. 2, No. 1, 1995, pp. 101-105.
 S. S. Dada, “Proterozoic Evolution of the Nigeria-Borborema Province,” In: R. J. Pankhurst, R. A. Trouw, B. B. Brito Neves and M. J. De Wit, Eds., West Gondwana: Pre-Cenozoic Correlations across the South Atlantic Region, Geological Society of London Special Publication, London, 2008, pp. 121-136.
 N. K. Grant, “The Geochronology of Precambrian Basement Rocks from Ibadan, Southwestern Nigeria,” Earth and Planetary Science Letters, Vol. 10, No. 1, 1970, pp. 28-38. doi:10.1016/0012-821X(70)90061-0
 V. M. Oversby, “Lead Isotope Study of Aplites from the Precambrian Rocks near Ibadan Southwestern Nigeria,” Earth and Planetary Science Letters, Vol. 27, No. 2, 1975, pp. 177-180. doi:10.1016/0012-821X(75)90027-8
 O. van Breemen, R. Pidgeon and P. Bowden, “Age and Isotopic Studies of Pan-African Granites Fromnorthcentral Nigeria,” Precambrian Research, 1977, Vol. 4, pp. 301-319.
 W. R. Fitches, A. C. Ajibade, I. G. Egbuniwe, R. W. Holt and J. B. Wright, “Late Proterozoic Schist Belts and Plutonism in NW Nigeria,” Journal of the Geological Society of London, Vol. 142, No. 2, 1985, pp. 312-337.
 M. Caen-Vachette and A. C. Umeji, “Geology and Geochronology of Okene Area: Evidence for an Eburnean Orogenic Cycle in South-Central Nigeria,” Journal of African Earth Sciences, Vol. 7, No. 1, 1987, pp. 121-126.
 M. A. Rahaman, “Recent Advances in the Study of the Basement Complex of Nigeria,” In: P. O. Oluyide, W. C. Mbonu, A. E. Ogezi, I. G. Egbuniwe, A. C. Ajibade and A. C. Umeji, Eds., Precambrian Geology of Nigeria, Geological Survey of Nigeria, Kaduna, 1988, pp. 11-41.
 A. E. Annor and S. J. Freeth, “Thermotectonic Evolution of the Basement Complex around Okene, Nigeria: With Special Reference to Deformation Mechanism,” Precambrian Research, Vol. 28, No. 3-4, 1983, pp. 269-281.
 A. C. Ajibade and J. B. Wright, “Structural Relationships in the Schist Belts Ofnorthwestern Nigeria,” In: P. O. Oluyide, W. C. Mbonu, A. E. Ogezi, I. G. Egbuniwe, A. C. Ajibade and A. C. Umeji, Eds., Precambrian Geology of Nigeria, Geological Survey of Nigeria, Kaduna, 1988, pp. 103-109.
 B. N. Ekwueme, “The Geological Evolution of Southeastern Nigeria,” University of Calabar Press, Calabar, 1987.
 C. T. Okonkwo, “Structural Evolution of Precambrian Basement Rocks of Jebba Area, S. W. Nigeria”, Global Journal of Geological Sciences, Vol. 6, 2008, pp. 145152. doi:10.4314/gjgs.v6i2.18764
 M. A. Rahaman, W. O. Emofurieta and M. Caen-Vachette, “The Potassic Granites of Igbeti Area: Further Evidence of the Polycyclic Evolution of the Pan-African Belt in Southwestern Nigeria,” Precambrian Research, Vol. 22, No. 1-2, 1983, pp.75-92.
 C. T. Okonkwo and J. A. Winchester, “Geochemistry of Granitic Rocks in Jebba Area, Southwestern Nigeria,” Journal of Mining and Geology, Vol. 40, No. 2, 2004, pp. 95-100.
 K. G. Cox, J. D. Bell and R. J. Pankhurst, “The Interpretation of Igneous Rocks,” George Allen and Unwin, London, 1979.
 A. Peccerillo and S. R. Taylor, “Geochemistry of Eocene calc-Alkaline Volcanic Rocks from the Kastamonu Area, Northern Turkey,” Contributions to Mineralogy and Petrology, Vol. 58, No. 1, 1976, pp. 63-81.
 B. R. Frost, C. G. Barnes, W. J. Collins, R. J. Arculus, D. J. Ellis and C. D. Frost, “A Geochemical Classifycation for Granitic Rocks,” Journal of Petrology, Vol. 42, No. 11, 2001. pp. 2033-2048.
 J. A. Pearce, N. B. W. Harris and A. G. Tindle, “Trace Element Discrimination Diagrams for the Tectonic Interpretation of Granitic Rocks,” Journal of Petrology, Vol. 25, No. 4, 1984, pp. 956-983.
 C. T. Okonkwo and J. A. Winchester, “Geochemistry and Geotectonic Setting of Precambrian Amphibolites and Granitic Gneisses in the Jebba Area, Southwestern Nigeria,” Journal of Mining and Geology, Vol. 32, No. 1, 1996, pp. 11-18.
 F. Corfu, J. M. Hanchar, P. W. O. Hoskin and P. Kinny, “Atlas of Zircon Textures,” Reviews in Mineralogy and Geochemistry, Vol. 53, 2003, pp. 469-495
 S. E. Jackson, N. J. Pearson, W. L. Griffin and E. A. Belousova, “The Application of Laser Ablation-Inductively coupled Plasma-Mass Spectrometry to in Situ U-Pb Zircon Geochronology,” Chemical Geology, Vol. 211, No. 1-2, 2004, pp. 47-69. doi:10.1016/j.chemgeo.2004.06.017
 J. Slama, J. Kosler, D. J. Condon, J. L. Crowley, A. Gerdes, J. M. Hanchar, M. S. A. Horstwood, G. A. Morris, L. Nasdala, N. Norberg, U. Schaltegger, B. Schoene, M. N. Tubrett and M. J. Whitehouse, “Plesovice Zircon—A New Natural Reference Material for U-Pb and Hf Isotopic Microanalysis,” Chemical Geology, Vol. 249, No. 1-2, 2008, pp. 1-35. doi:10.1016/j.chemgeo.2007.11.005
 C. Paton, J. Hellstrome, B. Paul, J. Woodhead and J. Hergt, “Iolite: Freeware for the Visualization and Processing of Mass Spectrometer Data,” Journal of Analytical Atomic Spectrometry, Vol. 26, 2011, pp. 2508-2518.
 K. R. Ludwig, “Isoplot/Ex Version 3.00: A Geochronological Toolkit for Microsoft Excel,” Berkeley Geochronology Center, Berkeley, 2003.
 J. P. Liegeois, W. Claessens, D. Camara and J. Klerkx, “Short-Lived Eburnian Orogeny in Southern Mali. Geology, Tectonics, U-Pb and Rb-Sr Geochronology,” Precambrian Research, Vol. 50, No. 1-2, 1991, pp. 111-136.
 G. S. de Kock, H. Theveniaut, P. M. W. Botha and W. Gyapong, “Timing the Structural Events in the Paleoproterozoic Bole-Nangodi Belt Terrane and Adjacent Maluwe Basin, West African Craton, in Central-West Ghana,” Journal of African Earth Sciences, Vol. 65, 2012, pp. 1-24. doi:10.1016/j.jafrearsci.2011.11.007
 C. D. Frost and B. R. Frost, “On Ferroan (A-type) Granitoids: Their Compositional Variability and Modes of Origin,” Journal of Petrology, Vol. 52, No. 1, 2011, pp. 3953. doi:10.1093/petrology/egq070
 M. Boher, W. Abouchami, A. Michard, F. Albarede and N. Arndt, “Crustal Growth in West Africa at 2.1 Ga,” Journal of Geophysical Research, Vol. 97, No, B1, 1992, pp. 345-369. doi:10.1029/91JB01640
 M. H. B. M. Hollanda, C. J. Archanjo, L. C. Souza, L. Dunyi and R. Armstrong, “Long-Lived Paleoproterozoic Granitic Magmatim in the Serido-Jaguaribe Domain, Borborema Province-NE Brazil,” Journal of South American Earth Sciences, Vol. 32, No. 4, 2011, pp. 287-300.
 N. Ennih and J. P. Liegeois, “The Boundaries of the West African Craton, with Special Reference to the Basement of the Moroccan Metacratonic Anti-Atlas Belt,” In: N. Ennih and J. P. Liegeois, Eds., The boundaries of the West African Craton, Geological Society of London, London, 2008, pp. 1-17.
 M. H. Arthaud, R. Caby, R. A. Fuck, E. L. Dantas and C. V. Parente, “Geology of the Northern Borborema Province, NE Brazil and Its Correlation with Nigeria, NW Africa,” In: R. J. Pankhurst, R. A. Trouw, B. B. Brito Neves, and M. J. De Wit, Eds., West Gondwana: Pre-Cenozoic Correlations across the South AtlanticRegion, Geological Society of London, London, 2008, pp. 49-67.
 E. L. Klein and C. A. V. Moura, “Sao Luis Craton and Gurupi Belt (Brazil): Possible Links with the West African Craton and Surrounding Pan-African Belts,” In: R. J. Pankhurst, R. A. Trouw, B. B. Brito Neves and M. J. De Wit, Eds., West Gondwana: Pre-Cenozoic Correlations across the South Atlantic Region, Geological Society of London, London, 2008, pp. 137-151.
 E. L. Klein, C. A. V. Moura, R. S. Krymsky and W. L. Griffin, “The Gurupi Belt, Northern Brazil: Lithostratigraphy, Geochronology, and Geodynamic Evolution,” Precambrian Research, Vol. 141, No. 3-4, 2005, pp. 83105. doi:10.1016/j.precamres.2005.08.003
 S. P. Neves, “Proterozoic History of the Borborema Province (NE Brazil): Correlations with Neighboring Cratons and Pan-African Belts and Implications for the Evolution of Western Gondwana,” Tectonics, Vol. 22, No. 4, 2003, p. 1031, doi:10.1029/2001TC001352