Sedimentological and Palyno-environmental appraisal of the late quaternary sediments, north-eastern Bornu Basin

Abstract An integrative study has been carried out on some Quaternary sediments of the Chad Formation in Tuma-1 and Sa-1 wells. They are located between 11° N and 13° 43′ 38″N; 8° 21′ 49″and 14° 40′ 22″E. Sedimentological study entailed textural analysis and thin section preparation on the disaggregated samples, while the palynological study involves the recovering of the age diagnostic species which gave clues to the paleoenvironmental settings for these sediments. The sediments consist predominantly of terrigenous and argillaceous mudstone with thin sandstone interbeds of point bar deposits of laterally migrating, moderate to high sinuosity river channels. The dominant sandstones are angular to subrounded, moderately poor sorted, fine modal mineralogically and texturally immature. The presence of Botryococcus braunii , freshwater algae, suggests a freshwater-lacustrine environment.