An appraisal of the geochemistry and geotectonic settings of the pan african rocks around akure and are-ekiti and environments, Southwestern, Nigeria

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.