Biostratigraphy Studies Of X-1 Well Chad Basin Nigeria

Abstract These i The biostratigraphic study of the Cretaceous sediments penetrated by X-1 well Chad Basin was carried out. A total of 112 ditch cutting samples were analyzed and these yielded eight genera and seventeen species of both arenaceous benthonic and planktonic microfossils. Sixteen Pollen species 11 spore species and 15 Dinoflagellate species making up 14 genera 8 genera and 14 genera respectively for the microflora. The accessory microflora encountered are fungal spore pediastrum radiolarian foraminifera test lining spike and gastropod tooth. Biostratigraphiic analysis established albian-Cenomanian age for the studied interval on the basis of the First Downhole Occurrence FDO of index Heterohelix Heterohelix moremani and Electarao bearing microfossils Elaterosporites protensus Elaterosporites verrucatus and Elaterocoplites castelaini. The depositional environments and paleobathymetric ranges of the studied well samples were determined and interpreted with the use of the microfaunal palynoflora assemblages and other accessories such as glauconite foramnifera test lining and fungal spore which reflects a transition from a marginal marine to a shallow marine inner neritic-middle neritic environment within the continental shelf. Two maximum flooding surfaces MFS and one sequence boundary SB were identified from maximum and minimum faunal abundance and diversity peaks respectively. The strata in the study are divided into transgressive systems tracts TST and Highstand Systems Tracts HST.