mmentology and palaeoenvironment of deposition of THE DEBA- FULANI MEMBER OF THE PINDIGA FORMATION AROUND KWADON-KANAWA AREA UPPER BENUE TROUGH NORTH EAST NIGERIA

The Deba Fulani Member is a sandy unit that occurs in the middle part of the Pindiga Formation and passes laterally to the Dumbulwa Member south of die Dumbulwa - Bage High and to the Gulani Member east of die Gongola River. The unit is made up of a lower part comprising Kanawa member-type shales and thin sandstones with Thalassinoides burrows. The major part of die Deba Fulani member is made up of repetitive cyclic arrangement, of a similar but thinner subfacies overlain by large scale tabular cross-bedded sub-unit with a general coarsening-up wards or progradational character and affected by minor vertical faults. The sandstones are very coarse-grained (-0.120), poorly to moderately sorted (0.910), platykurtic (1.440), and negatively skewed (-0.190). Petrographically, they are sub-angular to sub-rounded quartz arenites consisting of monocrystalline quartz and minor polycrystalline quartz, a general absence of feldspar and a low diversity of heavy mineral assemblage, suggesting a sedimentaiy source perhaps a reworked late- Cenomanian to early Turonian littoral sand deposited during a preceding transgressive interval. The mineral phases present in all samples of the Deba Fulani Member observed from XRD analysis indicates that they have quartz, feldspar, illite, muscovite, biotite, glauconite,