Lithostratigraphy and palynofacies appraisal of the northern depobelt onshore, Niger Delta

Abstract

Palynological and lithological studies of two exploratory wells located within northern depobelt of the Niger Delta have
been carried out. Seventy-six cutting samples were studied in order to determine the diverse lithofacies, biozonation, age,
palaeoenvironment and palynofacies based on the recovered taxa. The main lithofacies identified are sandstones, shaly
sand, sandy shale, silty shale, siltstone and shale of Benin and Agbada Formations. The sandstones are coarse to fine
grain and sub-angular to sub-rounded. A total of one hundred and twenty pollen, one hundred and fifty spores, twenty
algae and ten dinoflagellate cysts were recovered and identified. The palynological Zone of P500 and P520 Subzone
(1,975m-2354m); P400 Zone and P470/P480 (2,179m-2,481m [Umutu-5]); (2,354m-2,793m [Umutu-2]); P450 (2,481m-3,060m)
[Umutu-5]); (2,793m-3,163m [Umutu-2]); and P430 (3,060m- 3578m [Umutu-5]); 3,163m-3,380m [Umutu-2]). Subzones were
established in the studied wells. The palynomorphstaxa show the occurrence of high species diversity of land derived
palynoflora suggesting a near shore environment. The abundant land-derived palynomorphs and common dinoflagellate
cysts recorded include Polysphaeridium zoharyi, Lingulodinium machaerophorum and Spiniferite ssp. suggesting
shallow marine setting. The occurrence of Psilamonocolpites marginatus, Doualaidites laevigatus, Echitriporites
trianguliformis, Botryococcus braunii and Gemmamonoporites sp. suggests middle Eocene to early Oligocene and
middle to late Eocene ages respectively.