PETROCHEMICAL STUDIES OF PEGMATITES AROUND AWO, SOUTH WESTERN NIGERIA
Jimoh, M. T.
Journal Title:Journal of Environmental Issues and Agriculture in Developing Countries
Pegmatites around Awo bear valuable economic minerals; the rocks which trend mostly in the North East/South West are associated with other rock types like syenite, quartzite, porphyritic granite, biotite gneiss and migmatite gneiss. This study involves geological mapping of the study area showing its associated rock types, petrographic studies and chemical analysis were also considered. Five representative samples of the rock were investigated for their geology, petrography and geochemistry. Geological field mapping of the study area was carried out by collecting various rock types, studying their field occurrences, structural components and hand specimen observation. Petrographic studies entailed cutting polished sections of the rocks to identify each constituent mineral under petrological microscope while the geochemistry involved carrying out X-ray Fluorescence spectrometry analytical method on the digested samples at ACME Laboratory in Canada. The Petrographic studies revealed the modal composition of constituent minerals like microcline, plagioclase, quartz, mica (muscovite +/- biotite), opaque minerals and accessory minerals in the pegmatites. Geochemical analysis showed the mean weight of the major oxides like SiO2 , TiO2 , Al2 O3 , Fe2 O3 , MnO, MgO, CaO , Na2 O, K2 O, and P2 O5 . The AFM diagram plot falls on the calc-Alkaline rock suite while the harker's plot revealed that the plots between and SiO2 and other major elements are derived from the same geological environments. The study generally showed that the pegmatites of the study area bear semblance with pegmatites from other parts of the basement complex of South Western Nigeria with proven mineralisation.