The geochemistry of claystone-shale deposits from the maastritchian Patti formation,

An inorganic geochemical study of a claystone and shale sequence from the Patti Formation around Ahoko in the Southern Bida basin, Nigeria, was carried out to determine the basin’s depositional con-ditions, provenance and tectonics. Representative samples underwent mineralogical and geochemical analysis involving major, trace and rare earth element analysis. mineralogical studies using X-ray diffraction analysis revealed prominent kaolinite, dickite and illite peaks; accessory minerals included quartz and microcline. major element abundance showed that the shale samples had SiO2 (61.26%), Al2O3 (16.88%) and Fe2O3 (3.75%) constituting more than 79% of bulk chemical composition whilst claystone samples contained SiO2 (67.79%), Al2O3 (17.81%) and Fe2O3 (1.67%). Higher SiO2, Ba, Sr, V, and Nb concentrations were observed in claystone samples rather than shale whereas the shale samples were observed to be more Zr-, Ni- and Zn-enriched than the claystone ones. The shale and claystone samples showed slightly light rare earth enrichment and slightly flat heavy rare earth depleted patterns having a negative Eu and Tm anomaly. High TiO2 and Rb/K2O values also indicated that the shale and claystone samples were matured. Geochemical parameters such as U, U/Th, Ni/Co and Cu/Zn ratios indicated that these shales were deposited in oxic conditions; th