Trace Elements and Major Oxides Characteristic of the Geochemistry of Ajali Sandstone, South West, Anambra Basin, Nigeria
Authors: Ilevbare M, Omoruyi DI
The study aimed at characterizing the geochemical compositions of the Maastritchtian Sandstones of Ajali formation, Anambra Basin, in Fugar, Ayoguri, Auchi and Uzebba area of Edo State Nigeria. X-Ray Fluorescence (XRF) and Induced Coupled Plasma-Mass Spectrometry (ICP-MS) analyses were used to determine the sandstone composition. A total of 51 samples were collected at an interval of 0.6 m in 5 different locations within the Ajali formation in the Benin flank. The geochemistry of the major oxides revealed that SiO2 averaged 98.24%, Al2O3 averaged 0.79%, Fe2O3 averaged 0.47% and TiO2 averaged 0.31%. The Maastritchtian sandstones are rich in SiO2 but are depleted in all other major elements. The observed depletion in Al2O3, Fe2O3 and TiO2 is not only likely due to quartz dilution but also indicates that the studied sediments have suffered from intense weathering and recycling. Generally, low concentrations of Fe2O3 and TiO2 in all sandstones reflect low abundances of Ti-bearing minerals (biotite, ilmenite, titanite and titaniferous magnetite) in the analyzed samples. The SiO2/Al2O3 ratio averaged 180.24. This high value indicates mineralogical mature sediments. The mean Al2O3/TiO2 ratio of 3.25, indicates that the sediments were likely sourced from igneous rocks. The concentrations of chromium (Cr), which averages 142 mg/L and the low concentration of iron (Fe) at 15.90 mg/L both confirm a felsic source.
Affiliations: Department of Science Laboratory Technology, Faculty of Life Sciences, University of Benin, PMB 1154, Benin City, Edo State, Nigeria.
Keywords: Trace Elements, Metallic Oxides, Felsic Source, Igneous Source Rock, Anambra Basin
Published date: 2020/12/30