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Structural Geology of the Basement Complex Rocks in Iwaraja Area, Southwestern Nigeria

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The geological and structural evolution assessment of the Basement Complex rocks in Iwaraja area, southwestern Nigeria showed that the basement rocks comprise quartzites and quartz-schists of the Effon Psammite Formation, quartz-mica schists, biotite schists, migmatitic gneisses, granitic gneisses, late and post-tectonic granitic rocks including pegmatites, which have been subjected to two phases of deformation. The first phase is mainly a fabric forming deformation that also led to the development of moderately plunging mineral lineation. No minor fold of this phase was recognized. The second deformation phase gave rise to the development of Iwaraja (ductile) shear zone. Mylonitic foliation is sub-vertical and steeply dipping and while the mineral lineation is sub-horizontal and shallowly plunging. Within granitic gneiss mylonites, the shear zone is characterised by early and late open to tight folds of pegmatite dykes. Adjacent the shear zone, ptygmatic folds of quartzo-feldspathic veins in gneisses and crenulated cleavages that overprinted earlier schistosity surfaces in the quartz-mica schist also characterised this deformation phase. Extensional fractures in the various lithologies generally show bimodal orientations mainly in the WNW-ESE and NW-SE directions, which are nearly perpendicular to the regional metamorphic foliations. These deformation conditions depict structural features that are associated with internal zones of orogenic belts. Within the study area, the structures document late-Precambrian deformation during the closing stages of Pan-African orogenesis.


International Letters of Natural Sciences (Volume 58)
B. Adeoti and C. T. Okonkwo, "Structural Geology of the Basement Complex Rocks in Iwaraja Area, Southwestern Nigeria", International Letters of Natural Sciences, Vol. 58, pp. 16-28, 2016
Online since:
Sep 2016

[1] F.H. Hubbard, Precambrian crustal development in western Nigeria: indications from the Iwo region, Geological Society of America Bulletin. 86 (1975) 548-564.

DOI: 10.1130/0016-7606(1975)86<548:pcdiwn>;2

[2] A.A. Elueze, Geology of the precambrian schist belt in Ilesha area, southwestern Nigeria. In: P.O. Oluyide et al., (Eds. ), Precambrian geology of Nigeria, Geological Survey of Nigeria, (1988) 77-82.

[3] I.B. Odeyemi, A comparative study of remote sensing images of the structure of the Okemesi fold belt, Nigeria, ITC Netherlands Journal. (1993) 77–81.

[4] R. Caby, J.M. Boesse, Pan-African Nappe System in Southwest Nigeria: The Ife-Ilesha Schist Belt, Journal of African Earth Sciences. 33 (2001) 211-225.

DOI: 10.1016/s0899-5362(01)80060-9

[5] V.M. Oversby, Lead isotope study of aplites from the Precambrian rocks near Ibadan, south western, Nigeria, Earth Planetary Science Letters. 27 (1975) 177-180.

DOI: 10.1016/0012-821x(75)90027-8

[6] M.A. Rahaman, Recent advances in the study of the basement complex of Nigeria. In: P.O. Oluyide et al., (Eds. ), Precambrian geology of Nigeria, Geological Survey of Nigeria. (1988) 21-41.

[7] C.T. Okonkwo, V.Y. 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. 3 (2012) 1065-1073.

DOI: 10.4236/ijg.2012.35107

[8] C.T. Okonkwo, V.Y. Ganev, Geochemistry and geochronology of orthogneisses in Bode Saadu area, southwestern Nigeria and their implications for the palaeoproterozoic evolution of the area, Journal of African Earth Sciences. 109 (2015) 131-142.

DOI: 10.1016/j.jafrearsci.2015.05.012

[9] O. Van-Breemen, R. Pidgeon, P. Bowden, Age and isotopic studies of Pan-African granites from north-central Nigeria, Precambrian Research. 4 (1977) 301-319.

DOI: 10.1016/0301-9268(77)90001-8

[10] W.R. Fitches et al., Late-Proterozoic schist belts and plutonism in NW Nigeria, Journal of Geological Society of London. 142 (1985) 319-337.

DOI: 10.1144/gsjgs.142.2.0319

[11] R. Caby, Precambrian terranes of Benin- Nigeria and northeast Brazil and the late Proterozoic south Atlantic fit, Geological Society of America Special paper. 230 (1989)145-158.

DOI: 10.1130/spe230-p145

[12] R. Caby, Terrane assembly and geodynamic evolution of central-western Hoggar: a synthesis, Journal of African Earth Sciences. 37 (2003) 133-159.

DOI: 10.1016/j.jafrearsci.2003.05.003

[13] E. Ferre, G. Gleizes, R. Caby, Obliquely convergent tectonics and granite emplacement in the Trans-Saharan belt of eastern Nigeria: a synthesis, Precambrian Research, 114 (2002)199-219.

DOI: 10.1016/s0301-9268(01)00226-1

[14] R. Black et al., Outline of the Pan-African geology of Adrar des Iforas (rep. of Mall), Geol. Rundsch. 68(2) (1979) 543-564.

[15] A. Kroner, R.J. Stern, Pan African Orogeny. In: R.C. Selley, L.R.M. Cocks, R.I. Plimer (Eds. ), Encyclopedia of Geology. 1 (2005) 1-12.

[16] K.C. Burke, J.F. Dewey, Orogeny in Africa. In: T.F.J. Dessauvagie A.J. Whiteman, (Eds. ) African Geology, University of Ibadan. (1972) 583-608.

[17] R. Caby, J.M.L. Bertrand, R. Black, Pan-African Ocean Closure and Continental Collision in the Hoggar-Iforas segment. Central Sahara, in Precambrian Plate Tectonics. A. Kroner (ed. ) Elsevier Amsterdam, 1981, pp.407-434.

DOI: 10.1016/s0166-2635(08)70021-5

[18] B. Adeoti, Structural evolution of the basement complex rocks in Iwaraja area, southwestern Nigeria. unpublished master of technology thesis, Federal University of Technology, Akure, (2015).

[19] G.I. Alsop, R.E. Holdsworth, Shear zones - an introduction and overview. In: G. I. Alsop, R. E. Holdsworth, K. J. W. Mccaffrey, M. Hand, (Eds. ), Flow Processes in Faults and Shear Zones. Geological Society, London, Special Publications. 224 (2004).

DOI: 10.1144/gsl.sp.2004.224.01.01

[20] J. Carreras, E. Druguet, A. Griera, Shear zone-related folds, Journal of Structural Geology. 27 (2005) 1229-1251.

DOI: 10.1016/j.jsg.2004.08.004

[21] J.M. Boesse, O.O. Ocan, M.A. Rahaman, Lithology and the structure of the Ife-Ilesha area (abstract), 25th Annual Conf. Nig. Mining and Geosc. Soc. (1989) 6-7.

[22] C.T. Okonkwo, Early recumbent folding and thrusting in the Jebba area, S.W. Nigeria (abstract), 32nd Annual Conf. Nig. Mining and Geosc. Soc. (1996) 77.

[23] C.T. Okonkwo, Structural evolution of bode Saadu area, Southwestern Nigeria African, Journal of Science and Technology. 2(2) (2001) 17-24.

DOI: 10.4314/ajst.v2i2.44666

[24] G.I. Alsop, Relationships between distributed and localized shear in the tectonic evolution of a caledonian fold and thrust zone, northwest Ireland, Geol. Mag. 131 (1994) 123-136.

DOI: 10.1017/s0016756800010542

[25] J.G. Ramsay, M. Casey, R. Kligfield, Role of shear in development of helvetic fold-thrust belt of Switzerland, Geology. 11 (1983) 439-442.

DOI: 10.1130/0091-7613(1983)11<439:rosido>;2

[26] A.Y.B. Anifowose, I.B. Odeyemi, A.M. Borode, The tectonic significance of the Ifewara-Zungeru megastructure in Nigeria, Proceedings of the 1st international workshop on geodesy and geodynamics center for geodesy and geodynamics, Toro, Nigeria. (2007).

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