Sains Malaysiana 50(2)(2021): 315-326

http://dx.doi.org/10.17576/jsm-2021-5002-04

Petrography and Geochemical Characterization of a Granite Batholith in Idanre, Southwestern Nigeria

(Pencirian Petrografi dan Geokimia Batolit Granit di Idanre, Barat Daya Nigeria)

OLUWATOYIN O. AKINOLA^1,2, AZMAN A. GHANI²* & ELVAENE JAMES^2,3

¹Department of Geology, Faculty of Science, Ekiti State University, Ado-Ekiti, Nigeria

²Department of Geology, University of Malaya, 50603 Kuala Lumpur, Federal Territory, Malaysia

³Department of Geoscience, Faculty of Earth Science, Universiti Malaysia Kelantan, 17600 Jeli, Kelantan Darul Naim, Malaysia

Received: 29 February 2020/Accepted: 21 July 2020

ABSTRACT

Idanre granite batholith in southwestern Nigeria contain three rock types, namely, Older granite undifferentiated (OGu), Older granite porphyritic (OGp) and Older granite fine-grained (OGf). The granitoids intruded into a basement rock of primarily migmatite gneiss. Petrography indicates that quartz, orthoclase, hornblende, and biotite are common to all members while microcline is more prominent in OGp and plagioclase is poorly represented in OGf. Despite minor differences in petrographic features, the granite units generally have similar geochemical relationships. The average SiO₂ contents in OGp (70.49%), OGu (68.7%) and OGf (65.8%) are comparable to similar Pan-African suites located in eastern and northern Nigeria. Na₂O+K₂O-CaO versus SiO₂ diagram shows all the granite members are calcic, K₂O vs SiO₂ plot classify the granites as high-K calcic alkali to shoshonitic. ANK vs ACNK plot indicates they are peraluminous. Plot of A/CNK vs SiO₂ and K₂O vs Na₂O diagrams classified the rock as S-type granite. The granitoids are calc-alkaline with elevated Na₂O (>2.6%) and Al/(Na₂O+CaO) contents (OGu, 2.1-3.4; OGp, 2.4-3.1 and OGf, 2.2-2.9). The tectonic diagram (Rb vs (Y+Nb) indicates that the batholith is Within Plate Granite (WPG).

Keywords: Idanre granite; Pan-African suites; peraluminous; S-type granite; within plate granite

ABSTRAK

Batolit Granit Idanre di barat daya Nigeria mengandungi tiga jenis batuan iaitu granit tua tidak terbeza (OGu), granit tua porfirit (OGp) dan granit tua berbutir halus (OGf). Granitoid telah menerobos ke dalam batuan dasar yang terdiri daripada gneis migmatit. Kajian petrografi menunjukkan bahawa mineral kuarza, ortoklas, hornblend dan biotit biasa dijumpai pada ketiga-tiga batuan manakala mikroklin lebih banyak dalam OGp serta plagioklas kurang didapati dalam OGf. Walaupun terdapat perbezaan kecil dalam ciri-ciri petrografi, namun kebanyakan batuan granit mempunyai hubungan geokimia yang sama. Purata kandungan SiO₂ pada OGp (70.49%), OGu (68.7%) dan OGf (65.8%) adalah lebih kurang sama dengan suit Pan-Afrika yang terletak di timur dan utara Nigeria. Rajah Na₂O+K₂O-CaO melawan SiO₂ menunjukkan semua batuan granit adalah kalsik, manakala rajah K₂O melawan SiO₂ mengkelaskan batuan granit sebagai kalsik alkali tinggi-K kepada batuan shoshonit. Rajah ANK melawan ACNK menunjukkan batuan granit ialah peralumina. Rajah A/CNK melawan SiO₂ dan rajah K₂O melawan Na₂O mengelaskan batuan granit sebagai granit jenis-S. Selain itu, granitoid turut menunjukkan ciri kalsik kalkali dengan kandungan Na₂O (> 2.6%) dan kandungan Al/(Na₂O+CaO) (OGu, 2.1-3.4, OGp, 2.4-3.1 dan OGf, 2.2-2.9). Rajah tektonik (Rb melawan Y+Nb) menunjukkan bahawa Batolit Granit Idanre tergolong dalam Granit Dalam-Kepingan (WPG).

Kata kunci: Granit dalam-kepingan; granit Idanre; granit jenis-S; peralumina; suit Pan-Afrika

REFERENCES

Adetunji, A., Olarewaju, V.O., Ocan, O.O., Ganev, V.Y. & Macheva, L. 2016. Geochemistry and U-Pb zircon geochronology of the pegmatites in Ede area, southwestern Nigeria: A newly discovered oldest Pan-African rock in southwestern Nigeria. Journal of African Earth Science 115: 177-190.

Ajibade, A.C. 1980. Geotectonic evolution of the Zungeru region Nigeria. University College of Wales, Ph.D. Dissertation (Unpublished).

Ajibade, A.C. & Wright, J.B. 1989. The Togo-Benin-Nigeria shield: Evidence of crustal aggregation in the Pan-African belt. Tectonophysics 165(1-4): 125-129.

Anifowose, A.Y.B. & Kolawole, F. 2012. Talus Caves: Geotourist attractions formed by spheroidal and exfoliation weathering on Akure-Ado Inselbergs, southwestern Nigeria. Ethiopian Journal of Environmental Studies and Management 4(3): 1-6. 

Bessoles, B. & Trompette, M. 1980. Geology of Africa, the Pan-African channel "central African mobile zone (southern part) and Sudanese mobile zone. Pascal and Francis Bibliographic Databases 92: 396.

Black, R., Latouche, L., Liégeois, J.P., Caby, R. & Bertrand, J.M. 1994. Pan-African displaced terranes in the Tuareg shield (central Sahara). Geology 22(7): 641-644.

Caby, R. 1989. Precambrian terranes of Benin-Nigeria and northeast Brazil and the Late Proterozoic South Atlantic fit. In Terranes in the Circum-Atlantic Palaeozoic Orogens, edited by Dallmeyer, R.D. Geological Society of America Special Paper 230: 145-158.

Ekwueme, B.N. & Kroner, A. 2006. Single zircon ages of migmatitic gneisses and granulites in the Obudu Plateau: Timing of granulite-facies metamorphism in southeastern Nigeria. Journal of Africa Earth Sciences 44: 459-469.

Ferré, E.C., Gleizes, G. & Caby, R. 2002. Oblique convergent tectonics and granite emplacement in the Trans-Saharan belt of Eastern Nigeria: A synthesis. Precambrian Research 114: 199-219.

Ferré, E.C., Caby, R., Peucat, J.J., Capdevila, R. & Monie, P. 1998. Pan-African post-collisional ferro-potassic granite and quartz-monzonite plutons of Eastern Nigeria. Lithos 45: 225-279.

Ferré, E.C., Deleris, J.L., Lar, A.U. & Peucat, J.J. 1996. The Pan-African reactivation of Eburnean and Archaean provinces in Nigeria: A structural and isotopic data. Journal of the Geological Society of London 153: 719-728.

Frost, B.R., Barnes, C.G. & Collins, W.J. 2001. A geochemical classification for granitic rocks. Journal of Petrology 42: 2003-2048.

Ghani, A.A., Muzammil, S., Ng, T.F., Noer, E.H.I., Mohamad, T.M.Z., Nur, I., Quek, L.X., Ahmad, F.A.B., Meor, H.A.H., Jasmi, H.A.A. & Amira, F.M. 2019. Ce anomaly in I-type granitic soil from Kuantan, Peninsula Malaysia: Retention of Zircon in the weathering product. Sains Malaysiana 48(2): 309-315.

Goodenough, K.M., Lusty, P.A.J., Roberts, N.M.W., Key, R.M. & Garba, A. 2014. Post-collisional Pan-African granitoids and rare metal pegmatites in western Nigeria: Age, petrogenesis, and the ‘pegmatite conundrum’. Lithos 200: 22-34.

Haruna, I.V. 2014. Petrology and geochemistry of granitoids of the northern part of Adamawa Massif, NE Nigeria. Journal of Geology and Geosciences 3(177): 1-9.

James, E., Ghani, A.A., Asis, J. & Simon, N. 2019. Subduction roles for neogene volcanic rocks in Semporna Peninsula: Petrology and geochemistry perspective. Sains Malaysiana 48(11): 2473-2481.

Kröner, A. & Stern, R.J. 2005. Pan-African orogeny. Encyclopedia Geology 1: 1-12.

Le Bas, M.L., Le Maitre, R.W., Streckeisen, A. & Zanettin, B. 1986. A chemical classification of volcanic rocks based on the total alkali-silica diagram. Journal of Petrology 27: 745-750.

Le Maitre, R.W., Bateman, P., Dudek, A., Keller, J. & Lameyre, J. 1989. A Classification of Igneous Rocks and Glossary of Terms: Recommendations of the International Union of Geological Sciences Sub-Commission on the Systematics of Igneous Rocks.New York: Cambridge University Press.

Liégeois, J.P., Latouche, L., Boughrara, M., Navez, J. & Guiraud, M. 2003. The LATEA metacraton (Central Hoggar, Tuareg shield, Algeria): Behavior of an old passive margin during the Pan- African orogeny. Journal of African Earth Science 37: 161-190.

Liégeois, J.P., Black, R., Navez, J. & Latouche, L. 1994. Early and late Pan-African orogenies in the air assembly of terranes (Tuareg Shield, Niger). Precambrian Research 67(1-2): 59-88.

Maniar, P.D. & Piccoli, P.M. 1989. Tectonic discrimination of granitoids. Geological Society of America Bulletin 101: 635-643.

Odeyemi, I.B., Asiwaju-Bello, Y.A. & Anifowose, A.Y.B. 1999. Remote sensing fracture characteristics of Pan-African granite batholiths in the basement complex of parts of south western Nigeria. The Journal of Technoscience 3: 56-60.

Oyinloye, A.O. & Obasi, R.A. 2006. Geology, geochemistry, and geotectonic setting of the Pan-African granites and charnockite around Ado-Ekiti, southwestern Nigeria. Pakistan Journal of Scientific and Industrial Research 49(5): 299-308.

Pearce, J.A., Harris, N.B.W. & Tindle, A.G. 1984. Trace elements discrimination diagrams for the tectonic interpretation of granitic rocks. Journal of Petrology 25: 956-983.

Peccerillo, A. & Taylor, S.R. 1976. Geochemistry of eocene calc-alkaline volcanic rocks from the Kastamona area, northern Turkey. Contributions to Mineralogy and Petrology 58: 63-81.

Rahaman, M.A. 1988. Recent advances in the study of the basement complex of Nigeria. Geological Survey of Nigeria. Precambrian Geology of Nigeria, Geological Survey of Nigeria, Kaduna South.

Rahaman, M.A. 1976. Review of the Basement Geology of Southwestern Nigeria in Geology of Nigeria. Nigeria: Elizabeth Publishing Co.

Talabi, A.O. 2013. Mineralogical and chemical characterization of major basement rocks in Ekiti State, SW Nigeria. RMZ-Materials and Geoenvironment 60: 73-86.

Whalen, J.B., Currie, K.L. & Chappell, B.W. 1987. A-type granites: Geochemical characteristics, discrimination and petrogenesis. Contributions to Mineralogy and Petrology 95: 407-419.

*Corresponding author; email: azmangeo@um.edu.my