keywords: Bituminous sediments, ashing products, geochemistry, Afowo formation, Dahomey Basin
Eighteen tar sand samples were collected from a vast bituminous sand deposit in Dahomey Basin, Southwestern Nigeria. The tar sand samples were heated at 475oC for 24 h producing 18 ash samples. The chemical compositions (major, trace and rare earth elements) of the ash products were determined using FUS-ICP (Fusion-Inductively Coupled Plasma) and FUS-MS (Fusion-Mass Spectrometry) analytical techniques. SiO2, Al2O3 and Fe2O3 are the dominant oxides in the ash samples. The high concentrations of SiO2 (1.69-89.21% ), Al2O3 (0.22-18.87%) and Fe2O3 (0.06-6.81%) was due to quartz, feldspars and pyrite which constitute the main mineral phases of the ash bituminous sediment samples. Zr, V, Zn, Ba and Cr were found to be the most abundant trace elements with mean values of 289.3, 32.94, 31.39, 30.22 and 28.28 ppm, respectively. Furthermore, the correlation matrix result including factor analysis showed that the great majority of elements detected have a common source and also the chemistry of the bituminous sediments was influenced by the associated aluminosilicate minerals that constitute the matrix.
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