Abstract: The study of geochemistry, classification and geotectonics of granitic rocks of Akure, Southwestern Nigeria are undertaken. Geochemical analysis classified the rocks suites as quartz-rich, silica-saturated, alumina-saturated, dorminant peraluminous, S-type, slightly metaluminuos, I-type and A-type granites. A plot of total alkalies-silica of alkaline and sub-alkaline rock suites indicated granite, syenite, quartz-diorite, gabbro, monzogranite and monzodiorite as rock types. The sub-alkaline rocks exhibited evidence of crystal fractionation from a magmatic melt generated by partial melting of basaltic materials. The Y/Nb ratio (1.39-7.03 1.2) affirmed that magmas that produced the rocks were either derived from crustal or mixed sources. Significant variations in the correlation of Sr, Zr, Ba and Rb with SiO2 suggested the involvement of more than one sources in the genesis of the rocks. The depletion of Ba (0.48-8.76), the presence of distinct negative Eu in the REE pattern, with a strong negative correlation of Al2O3 and CaO with increasing SiO2 are characteristics suggestive of an extensive fractionation of plagioclase. These rocks were involved in the active magmatic and tectonic activities with post collision uplift and late orogeny that were in conformity with the tectonic scenario of Pan-African granite. These geodynamic activities resulted in the emplacement of granitic rocks suites into the host rock.
Romanus Obasi, Henry Madukwe and Olajumoke Adewumi, 2021. Geochemistry, Classification and Geotectonic Studies of Pan-African Rocks Around Akure, Southwestern Nigeria. Research Journal of Applied Sciences, 16: 85-101.