Browsing by Author "Aina, I.O"

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    Preliminary Investigation of Petrographic and Geochemical Characteristics of Crystalline Rocks in Jebba Central Nigeria
    (2019) Omotoso, Oladele Ajiboro; Ojo, Olusola Johnson; Aina, I.O; Udeafor, J.I.; Alebiosu, Mercy Titilayo
    The preliminary investigation of petrographic and geochemical characteristics of crystalline rocks in Jebba, central Nigeria was carried out in order to establish the various rock types in the area. Petrographic studies were carried out using thin sections of the rock samples and geochemical analysis was carried out using X-ray Fluorescence (XRF) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Field mapping indicated that the area is underlain by granite (porphyritic granite), granite gneiss, quartzite and schist. The petrographic studies indicated the main mineral assemblages in the crystalline rocks as; quartz, plagioclase, microcline and biotite. Results of geochemical analysis established SiO2 and Al2O3 as dominant major oxides in the investigated rocks ranging from 46.66 to 97.6 wt. % and 0.25 to 17.48 wt. % respectively. Average values of CIA (Chemical Index of Alteration), PIA (Plagioclase Index of Alteration) and CIW (Chemical Index of Weathering) of the rocks are 59.2, 65.0 and 72.8 (granite gneiss); 58.4, 62.9 and 70.6 (granite); 67.7, 79.9 and 83.3 (quartzite); 57.9, 61.4 and 66.4 (schist) respectively. The intensive weathering of the rocks would have contributed to the concentration of metals in the water phase of the study area. Most of the rare earth elements in granite gneiss are highly enriched with respect to abundance in the earth crust having values greater than 1ppm while granite and quartzite are depleted in these elements.