"International Journal of Geography, Geology and Environment"

Author(s): Akinola Oluwatoyin O and OlaOlorun Olusola A

Abstract: This study presents lithologic and petrogenetic investigation of bedded quartzite from Okemesi and massive quartzites from Ado-Ekiti in southwestern Nigeria. Okemesi quartzite is extensive, thickly bedded and steeply dipping while quartzite from Ado-Ekiti is hummocky, ferruginous, fractured, and non-bedded. Analytical results reveal average SiO₂ Okemesi (94.74 %) and Ado-Ekiti quartzite (93.88%). Similarly, average Rb/Sr are 0.74 and 1.22 while Sr/Ba are 0.89 and 0.69, respectively. These parameters portray them as supracrustal rocks of continental origin. Implying quartzites in Ekiti are non-schistose pelitic metasediments. Na₂O/Al₂O₃ versus K₂O/Al₂O₃ diagram revealed the quartzite units are sedimentary in origin and are compositionally similar to the Scottish metapelite and Igarra quartz mica-schist. Chemical Index of Alteration (CIA) of Okemesi quartzite (88 %) and Ado-Ekiti quartzite (91 %) which are relatively high signifies intense chemical weathering of their source rocks. Index of compositional variability (ICV) of Okemesi quartzite (0.83) and Ado-Ekiti quartzite (0.74) indicate the quartzites are immature pelite.

DOI: 10.22271/27067483.2022.v4.i2a.116

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