ABSTRACT
Seven (07) samples of granitic rocks from Igarra-Ugbogbo area in Akoko-Edo Local Government Area of Southwestern Nigeria were obtained with the aim of determining their geochemical and mineralogical properties using XRF, XRD techniques and thin section. Results of the analysis revealed the presence of SiO2 (56.99-71.22wt.%), Al2O3 (13.55-20.76wt.%), Fe2O3(T)* (3.55-5.85wt.%), K2O (0.95-7.21wt.%), Na2O (2.82-3.98wt.%), CaO (1.88-3.03wt.%) and MgO (0.50-1.56wt.%). The abundance of these major oxides in the samples showed that samples UGB 02, 3, UGB 04, UGB 05 and UGB 07 are probably from a felsic magma and UGB 01 and UGB 06 from an intermediate magma. Using Al2O3 classification scheme, its showed that all the samples are peraluminous. The XRD analysis revealed the presence of quartz, alkali feldspars (microcline, orthoclase and sanidine), plagioclase feldspars (albite and anorthite), muscovite, lepidolite, petalite, amblygonite and illite. The modal composition of the quartz, alkali feldspar, plagioclase were plotted on a QAP diagram which showed that the rock falls within the granitoidal class. Thin section results revealed the optical properties of the minerals present and their behaviours to light. The photomicrographs reveal the presence of various minerals such as quartz, microcline, plagioclase, muscovite and biotite. The trace element plot of Rb versus (Y+Nb) reveal their tectonic setting to be from post-collision to
