Distribution of Heavy Minerals in Sediments of Osun River Basin Southwestern Nigeria

Heavy minerals assemblage of sediments in Osun River basin have been studied in five states in Southwest Nigeria to determine their concentrations and provenance. Twenty-five sediment samples were analysed for heavy mineral assemblage determination. The separation of these minerals was carried out using bromoform (Specific gravity 2.85) and slide examination under the petrographic microscope. The heavy minerals assemblages of Zircon, Tourmaline, Rutile, Silimatate, Garnet, Epidote and Staurolite indicate its derivation from mixed sources of acid igneous rock to medium and high grade metamorphic rocks. The calculated ZTR % values varied between 21.1% in Ekiti to 56.7% in Lagos state and the mean ZTR (Zircon, Tourmaline, Rutile) percentage indices was 36.4%. The two most abundant are Staurolite and Rutile with 43.92% and 11.95% respectively. We found that their concentrations and sizes increase from Ekiti state in the upper section of Osun basin to Lagos in the southern part of the basin according to coastal drift whereas the mineralogical component remains constant.