Geochemical and Petrographic Studies of Some Quartz Mica Schists in Igarra and Environs, Southwestern Nigeria

Ovie Odokuma-Alonge; Susan Chioma Dibani

Ovie Odokuma-Alonge Department of Geology, Faculty of Physical Sciences, University of Benin, Benin City, Edo State, Nigeria
Susan Chioma Dibani

Keywords: Petrography, Schist, Chemical, Analysis, Facies

Abstract

Five schist samples from Igarra and Environs in Akoko Edo area of Southwestern Nigeria were obtained with the aim of determining their geochemical properties using XRF techniques and also for petrographic analysis. Results from the geochemical analysis revealed the presence of SiO₂ (54.65-59.01wt.%), Al₂O₃ (21.98-25wt.%), Fe₂O₃ (3.77-5.67wt.%), MgO (0.56-1.68wt.%), K₂O (4.62-6.56wt.%) and Na₂O (0.48-0.96wt.%). The geochemical evaluation revealed that the schists were probably generated from the metamorphism of shale. Discrimination diagrams show peraluminous character and plots within the metasedimentary field which also supports a sedimentary protolith. The A-CN-K plot reflects that the shale suffered moderate chemical weathering before being subjected to metamorphism. The petrographic studies also revealed the characteristics of the minerals present in the rock which shows the alignment of platy minerals in a preferred direction that aided the characteristic features of the rock foliation. Modal composition shows mineralogical assemblages of quartz + plagioclase + microcline + biotite + muscovite + hornblende which indicates that the schist belong to the greenschist facies grade.

References

Adegbuyi, O., Ogunyele A.C., Odindu, M., Erinfolami, T.G., 2017. Geochemical characteristics and petrogenesis of Basement rocks in Idoani Area, Ondo State, Southwestern Nigeria. International Journal of Advances Geosciences 5, 102-108.

Ajibade, A.C., Wright, J.B., 1988. Structural Relationship in the Schist Belts of North Western Nigeria. In P.O Oluyide et al (Eds). Precambrian geology of Nigeria. A Publication of Geological Survey, pp 103-109.

Alaku, O.I., Moshood, I.O., Agbor, T.A., Amos, A.A. 2017. Geochemical Characteristic and Petrogenesis of Malumfashi Schist around Tandama Area, North-Western Nigeria. British Journal of Applied Science & Technology 20 (1), 1-14.

Bishop, A.C., Woolley, A.R., Hamilton, W.R., 1999. Cambridge Guide to Minerals, Rocks and Fossils. Cambridge University Press. p. 153. Essentials of Geology, 3rd Ed, Stephen Marshak.

Dombrowski, A., Henjes-Kunst, F., Hohndorf, A., Kroener, A., Okrusch, M., Richter, P., 1995. Orthogneisses in the Sperssart Crystalline Complex, north-west Bavaria: Silurian granitoid magmatism at an active continental margin. Geologic Rundschau. Vol. 84, 399-411.

Garrel, R.M., Mackenzie, F.T., 1971. Evolution of Sedimentary Rocks. W.W. Norton and Co. Int. New York, 394 p.

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

Marshak, S., Wilkerson, M.S., Wilkerson, M.B., 2009. Essentials of Geology(3rd ed.). W.W. Norton.
Miyashiro, A., 1973. Metamorphism and metamorphic belts. George Allen & Unwin Ltd. London, 492.

Nesbitt H.W., Young G.M., 1982. Early Proterozoic climates and plate motions inferred from major element chemistry of lutites. Nature 299 (5885), 715-717.

Obioha, Y.E., Ekueme, B.N., 2012. Geochemistry of Schists of Northwest Obudu Plateau, Southeastern Nigeria. Global Journal of Geological Sciences 10, 157-165.

Odeyemi, I.B., 1976. Preliminary report on the field relationships of Basement complex rocks around Igarra, Mid-Western State, Nigeria: Geology of Nigeria. University of Ife, Nigeria.

Odeyemi, I.B., 1988. Lithostratigraphy and structural relationships of the Upper Precambrian Metasediments in Igarra area, southwestern Nigeria.

Oyebamiji, A.O., Okunlola, A.O., 2016. Geochemical Evaluations and Economic Potentials of Rare Metal Pegmatites in Iludun area, Southwestern Nigeria. IQSR Journal of Applied Geology and Geophysics 4, 72-78.

Pearce, M., Gorman, B.E., Birkett, T.C., 1975. The relationship between major element chemistry and tectonic environment of basic and intermediate volcanic rocks. Earth and Planetary Science Letters 36 (1), 121-132.

Usman, M.A., Ibrahim, A.A., 2017. Petrography and geochemistry of rocks of Northern part of Wonaka Schist Belt, Northwestern Nigeria. Nigerian Journal of Basic and Applied Science 25 (2), 87-99.