Geochemistry of granitic rocks in Jebba area, southwestern Nigeria

Okonkwo, C. T.; Winchester, J. A.

doi:10.4314/jmg.v40i2.18814

Cited by 9 publications

(12 citation statements)

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“…These granitic rocks termed the "Older Granites" in Nigeria have been dated severally at 750-500Ma (van Breemen, Pidgeon, & Bowden, 1977;Rahaman et al, 1983;Fitches, Ajibade, Egbuniwe, Holt, & Wight, 1985;Ferre et al, 1998;Ekwueme & Kroner, 1998). Similar granitic rocks have also been studied in various parts of the Nigerian basement complex-northern Nigeria (Olarewaju & Rahaman, 1982), Jebba area (Okonkwo & Winchester, 2004), Obudu Plateau, southeastern Nigeria (Ukwang & Ekwueme, 2009), Kabba-Lokoja area (Ezepue & Odigi, 1993), among others.…”

Section: Introductionmentioning

confidence: 98%

Petrochemistry and Geotectonic Setting of Granitic Rocks in Aderan Area, S.W. Nigeria

Okonkwo¹,

Folorunso²

2012

JGG

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Aderan area, southwestern Nigeria is underlain by metaigneous and metasedimentary rocks which have been intruded by granitic rocks of probable Pan-African (ca. 600 Ma) age. Four types of granitic rocks have been identified in the area, including granitic gneisses, medium-grained granite, porphyritic granite and granodiorite. Geochemical analysis show that the rocks are largely calc-alkaline. The granodiorite is less siliceous and more calcic, and also contains less Ba, Nb and Rb, and more Sr, Ce and La than the granites. Tectonically, the rocks classify as volcanic arc and syn-collisional and possibly late-to- post-collisional granitic rocks with respect to the Pan-African orogeny. Chemical characteristics indicate that these rocks were derived from partial melting of mafic to semi-pelitic (metasedimentary) crustal rocks under conditions of intermediate oxygen fugacity and activities of H₂O.

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Section: Introductionmentioning

confidence: 98%

Petrochemistry and Geotectonic Setting of Granitic Rocks in Aderan Area, S.W. Nigeria

Okonkwo¹,

Folorunso²

2012

JGG

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“…The Oka-Akoko grey gneiss is similar in composition to the Kabala gneiss which is granodioritic [19]. The granite gneiss of Oka-Akoko is similar to Idofin-Osi-Eruku and Jebba granite gneisses which are also peraluminous, potassic, calcic to alkalic and silica-rich and inferred to be products of partial melting of crustal rocks [16,17].…”

Section: Discrimination Diagrams Of Garrel and Mckenzie And Tarney Indimentioning

confidence: 69%

“…However, the grey gneiss contains more TiO2, Al2O3, FeOtotal, MgO, CaO, and Na2O than the granite gneiss and this account for the higher amount of opaques (iron minerals and others), hornblende, and plagioclase in the grey gneiss than the granite gneiss. Oka-Akoko granite gneiss has lower silica content than the Arigidi, Ilesha, Jebba and Idofin-Osi-Eruku granite gneisses but higher silica content than the NE Obudu granitic gneiss (Table 3) [11,[15][16][17][18]. The Al2O3 and total alkali (Na2O + K2O) contents of Oka-Akoko granite gneiss is higher than that of Arigidi, Ilesha, Jebba, Idofin-Osi-Eruku and NE Obudu granitic gneisses indicating its higher peraluminous and alkaline nature.…”

Section: Resultsmentioning

confidence: 99%

Petrology and Geochemistry of Basement Gneissic Rocks Around Oka-Akoko, Southwestern, Nigeria

Adegbuyi¹,

Ogunyele²,

Akinyemi³

2018

Malays. j. geosci.

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The gneissic rocks of Oka-Akoko area forms part of the Migmatite-Gneiss-Quartzite Complex of the Southwestern Nigerian Basement Complex. The petrologic units in the study area include grey gneiss, granite gneiss, Older granite, charnockite and minor felsic and basic rocks. Twelve gneissic rock samples comprising six granite gneiss and six grey gneiss from the area were collected for petrographic and geochemical analyses. Petrographic analysis revealed that the granite gneiss is more enriched in quartz and alkali feldspar than the grey gneiss. The grey gneiss is richer in plagioclase, hornblende and opaques compared to the granite gneiss. Interpretation of petrographic and geochemical analyses results revealed that Oka-Akoko granite gneiss and grey gneiss were derived from igneous protoliths of granitic and granodioritic compositions respectively. The grey gneiss is ferroan, alkalic to alkali-calc and metaluminous suggesting that its igneous protolith(s) is a M-type granitoid derived from melting of rocks from upper mantle or lower crustal region under conditions of limited availability of H2O and low oxygen fugacity while the granite gneiss is magnesian, alkali-calc and slightly peraluminous suggesting that its igneous protolith(s) is an I-type granitoid derived from the partial melting of crustal igneous rocks.

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“…Okonkwo and Winchester, 2000), whereas the garnet-hornblende gneiss, the charnockites and granulites reflect an igneous parentage. The protolith of the garnet-sillimanite gneiss and biotitegarnet schist probably was a shale-greywacke sequence (Ekwueme, 1998).…”

Section: Geochemistrymentioning

confidence: 97%

Single zircon ages of migmatitic gneisses and granulites in the Obudu Plateau: Timing of granulite-facies metamorphism in southeastern Nigeria

Ekwueme

Kröner

2006

Journal of African Earth Sciences

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Geochemistry of granitic rocks in Jebba area, southwestern Nigeria

Cited by 9 publications

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Petrochemistry and Geotectonic Setting of Granitic Rocks in Aderan Area, S.W. Nigeria

Petrochemistry and Geotectonic Setting of Granitic Rocks in Aderan Area, S.W. Nigeria

Petrology and Geochemistry of Basement Gneissic Rocks Around Oka-Akoko, Southwestern, Nigeria

Single zircon ages of migmatitic gneisses and granulites in the Obudu Plateau: Timing of granulite-facies metamorphism in southeastern Nigeria

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