GEOCHEMICAL AND MINERALOGICAL STUDY OF THE CRETACEOUS SEDIMENTS IN KERI KERI, FIKA, GONGILA, AND BIMA SANDSTONE FORMATION BORNU BASIN, NORTH-EASTERN NIGERIA

The mineralogical and geochemical composition of Cretaceous and Tertiary sediments of the Bornu Basin, northeastern Nigeria penetrated by Kanadi Wells, have been studied towards deducing aspects of their derivation and deposition. The sediments comprising the Bima Sandstone Formation, sandy-shale Gongila Formation, and, clayey and shaley Fika Formation are mainly composed of quartz (35-58%) and kaolinitic clay (0-50%) with the quartz sympathetically decreasing up the succession. The basal Bima Sandstone Formation is notably arkosic with 25% albite feldspars. A significant abundance (15-25%) of barite also characterized the sandy units of the Bima and Fika Formations. The SiO2/Al2O3 ratios of 5 to 6 underline the general sandy nature of the sediments while the calcareous nature of Bima and Gongila Formation has reflected in their higher (NaO+K2O)/(MgO+CaO) ratios of 1 to 2. In addition, the occurrence of significant 2-3% SO3 constituents showed the important occurrences of barite in the Bima, Gongila, and lower parts of, Fika Formations. The sediments are mostly shallow water deposition in tropical-like paleoenvironment(s).