Major and Trace Element Evaluation of the Campano-Maastrichtian Sediments of Anambra Basin Exposed around Enugu, Nigeria
An integrated geochemical and sedimentological study of the Campano- Maastrichtian sediment of Ajali and Owelli Formation exposed within the southern portion of the Anambra basin was undertaken to determine the
sandstone provenance, tectonic setting, and paleo-weathering conditions. All sandstone samples are enriched in quartz (Q) but poor in feldspar (F) andlithic-fragments (L). The major-element concentrations of these sandstones reveal the relative homogeneity of their source. Geochemically, the sandstones are classified as quartzarenite, sub-litharenite, and subarkose. Tectonic setting discrimination diagrams suggest a passive continental margin. The sediments are enriched in SiO2 and depleted in Na2O, CaO and TiO2.Chemical index of weathering (CIW) of the sample suggests intense recycling and high degree of weathering in a humid climatic condition. Results of the elemental ratios critical of provenance compared to those of felsic and basic derived sediment of UCC and PAAS values suggests a felsic source rock. Cu/Zn, U/Th, Ni/Co and (Cu+Mo)/Zn paleo-oxygenation ratios used as redox parameters depicts an oxic environment. Finally, presence of minerals, like Anatase, Rutile and Microcline depicts an igneous and metamorphic source terrain.
Keywords: Provenance, Sub-litharenite, Sandstone, Minerals.