Obasi Romanus Ayoola ✉

Department of Geology, Ekiti State University, Ado Ekiti, Ekiti State, Nigeria

Received: Nov 17, 2022/ Revised:  Dec 24, 2022/ Accepted: Dec 20, 2022

(✉) Corresponding Author: romanus.obasi@eksu.edu.ng

Abstract

The geochemical characteristics of the Pan-African rocks from Akure and Are –Ekiti and Environs show a minor variations in the contents of silica (SiO2 50.18-98.92 wt%,), alumina, Al2O3 (0.26-17.26wt%), potash (K2O, 0.07-5.98wt%), and iron F2O3 (0.52-10.77wt%) respectively. The rocks suites from both areas are also characterized by high alumina, high silica, and presence of biotite, microcline, monzogranite, syenogranites, diorite, granodiorite as well as granites. The rocks from both studied areas plotted into the S-Type and I-Type granites suggestive of their derivation from mixed sources. The presence of shoshonitic series suggests rock association characterized by k-rich, high Na2O + K2O and low TiO2.  The granites from b Akure and Are Ekiti and environs are characteristically potassic with metaluminous I-Type and peraluminous S-Type affinity and elong to high-K calcalkaline to shoshonitic series. The rocks are strongly enriched in Ba-Sr with pronounced negative Eu anomaly, belonging to syn-to post collisional tectonic setting. However, the plots of Rb versus Y+Nb, Rb versus Ta + Yb, Ta versus Yb, Nb versus Y, as well as Ta versusYb respectively showed that the granitic rocks of Akure and Are Ekiti and environs were formed in the tectonic environments of volcanic arcs, syn-collisional and post collisional as well as within plate settings, suggesting their derivation from fractional crystallization and partial melting.

Keywords: Appraisal, Geochemistry, Characteristics, Geotectonic Setting

References

Ayodele, O. S. (2015). The geology, geochemistry and petrogenetic studies of the Precambrian Basement rocks around Iworoko, Are and Afao area, Southwestern Nigeria. J Geol Geophys4(212), 2.

Bathelor, R. A., & Bowden, P. (1985). Petro genetic interpretion of granitoid rock series using mulicationic Parametra Chemical Geology.

Harris, N. B., Pearce, J. A., & Tindle, A. G. (1986). Geochemical characteristics of collision-zone magmatism. Geological Society, London, Special Publications19(1), 67-81.

Irvine, T. N., & Baragar, W. R. A. (1971). A guide to the chemical classification of the common volcanic rocks. Canadian journal of earth sciences8(5), 523-548.

Jakeš, P., & White, A. J. R. (1971). Composition of island arcs and continental growth. Earth and Planetary Science Letters12(2), 224-230.

Janoušek, V., Moyen, J. F., Martin, H., Erban, V., & Farrow, C. (2015). Geochemical modelling of igneous processes: principles and recipes in R language. Springer.

Le Bas, M. J., & Streckeisen, A. L. (1991). The IUGS systematics of igneous rocks. Journal of the Geological Society148(5), 825-833.

Le Maitre, R. W. (1989). A classification of igneous rocks and glossary of terms. Recommendations of the international union of geological sciences subcommission on the systematics of igneous rocks.

Loiselle, M. C. (1979). Characteristics and origin of anorogenic granites. In Geological society of America abstracts with programs (Vol. 11, p. 468).

Maniar, P. D., & Piccoli, P. M. (1989). Tectonic discrimination of granitoids. Geological society of America bulletin101(5), 635-643.

Middlemost, E. A. (1994). Naming materials in the magma/igneous rock system. Earth-science reviews37(3-4), 215-224.

Mohamed, F. H., & Hassanen, M. A. (1997). Geochemistry and petrogenesis of Sikait leucogranite, Egypt: an example of S-type granite in a metapelitic sequence. Geologische Rundschau86(1), 81-92.

Nakamura, N. (1974). Determination of REE, Ba, Fe, Mg, Na and K in carbonaceous and ordinary chondrites. Geochimica et cosmochimica acta38(5), 757-775.

Obasi, R. A., & Maduekwe, H. Y. (2021). Potential Ecological and Health Risk Assessment of Dumpsite from Ibadan, Southwestern Nigeria. Nature Environment and Pollution Technology20(2), 833-842.

Oversby, V. M. (1975). Lead isotopic study of aplites from the Precambrian basement rocks near Ibadan, southwestern Nigeria. Earth and Planetary Science Letters27(2), 177-180.

Oyinloyea, A. O., & Obasi, R. (2006). Geology, geochemistry and geotectonic setting of the Pan-African granites and charnockites around Ado-Ekiti, Southwestern Nigeria. Biological Sciences-PJSIR49(5), 299-308.

Pearce, J. A., & Cann, J. R. (1973). Tectonic setting of basic volcanic rocks determined using trace element analyses. Earth and planetary science letters19(2), 290-300.

Pearce, J. A., Harris, N. B., & Tindle, A. G. (1984). Trace element discrimination diagrams for the tectonic interpretation of granitic rocks. Journal of petrology25(4), 956-983.

Pearce, T. H., Gorman, B. E., & Birkett, T. C. (1975). The TiO2–K2O–P2O5 diagram: a method of discriminating between oceanic and non-oceanic basalts. Earth and Planetary Science Letters24(3), 419-426.

Peccerillo, A., & Taylor, S. R. (1976). Geochemistry of Eocene calc-alkaline volcanic rocks from the Kastamonu area, northern Turkey. Contributions to mineralogy and petrology58(1), 63-81.

Rahaman, M. A. (1988). Recent advances in the study of the basement complex of Nigeria. Pre Cambrian geology of Nigeria, 11-41.

Sayyed, M. R. G. (2014). Lithological control on the mobility of elements during chemical weathering. Comunicaçõe Geológicas101(1).

Schandl, E. S., & Gorton, M. P. (2002). Application of high field strength elements to discriminate tectonic settings in VMS environments. Economic geology97(3), 629-642.

Shahabpour, J. (2007). Island-arc affinity of the Central Iranian volcanic belt. Journal of Asian earth sciences30(5-6), 652-665.

Sylvester, P. J. (1989). Post-collisional alkaline granites. The Journal of Geology97(3), 261-280.

Taylor, S. R. (1964). Abundance of chemical elements in the continental crust: a new table. Geochimica et cosmochimica acta28(8), 1273-1285.

Vernikovskaya, A. E., Romanov, M. I., Kadilnikov, P. I., Matushkin, N. Y., & Romanova, I. (2017, December). Shoshonites and Associated Calc-Alkaline Rocks from the Eastern Sayan, Central Asian Orogenic Belt: Geochemistry and Tectonic Setting. In AGU Fall Meeting Abstracts (Vol. 2017, pp. V13D-0412).

Villaseca, C., Barbero, L., & Rogers, G. (1998). Crustal origin of Hercynian peraluminous granitic batholiths of Central Spain: petrological, geochemical and isotopic (Sr, Nd) constraints. Lithos43(2), 55-79.

Whalen, J. B., Currie, K. L., & Chappell, B. W. (1987). A-type granites: geochemical characteristics, discrimination and petrogenesis. Contributions to mineralogy and petrology95(4), 407-419.

Wilson, C. C. (1991). Geology of the Quaternary Bridgewater Formation of southwest and central South Australia (Doctoral dissertation, Flinders University of South Australia).

How to cite this article

Ayoola, O. R. (2022). An appraisal of the geochemistry and geotectonic settings of the pan-African rocks around Akure and are-Ekiti and environments, southwestern, Nigeria. Chemical and Environmental Science Archives, Vol. 2(4), 46-62. https://doi.org/10.47587/CESA.2022.2404

 

License                      Article Metadata

This work is licensed under a Creative Commons Attribution 4.0 International License.

View Details