Palynological Evidence of a Campanian-Maastrichtian Age of the Central Bida Basin, Nigeria: Implication for Paleoenvironment, Paleoclimate and Hydrocarbon Prospectivity

Abstract

The result of the study herby documented is probably the first of its kind in terms of the source of the samples (ditch cutting) used for the palynological analysis. The ditch cuttings analysed were sampled from the pilot exploratory well drilled at Kudu of the Central Bida Basin. The well was drilled to a depth of 71m and sampled at 1m interval giving a total of 71 ditch cuttings. The studied samples are mainly sandstones, Mudstone and coaly carbonaceous shales. Palynological analysis were performed on the 71 samples obtained from the well using the conventional acid method of palynological preparation technique and the microscopic analysis of the palynoslides. The well is very rich in palynomophs both in terms of taxonomical species and quantity and has afforded a clear interpretation of the paleohistory of the section of the Basin penetrated. Palynomophs identified include Monocolpitessp, Proteaciditessigalii, psilatricolporistessp, Tricolporollennitessp, Acrostichumaureum, Cyathiditessp, Laevigatosporitessp, Rugulatisporitescaperatus, and Verrucatosporitessp. Three (3) palynostratigraphic zones from Late Cambrain to Early Maastrischtian are proposed. The zones, in stratigraphic ascending order, are as follows: Proteaciditessigalli – Psilotricolporitessp interval range zone, Longapertitesvandeburgii-Longapertitesmicrofovelatus concurrent range zone and Monocolpitesmarginatus-Inaperturopollenites sp. Interval range zone. The vertical distribution of the palynoforms and the few presence of dinoflagellates show only one major paleodepositional environment; the terrestrial to nearshore type characterized by dominant terrestrial spores and pollen occasionally inundated by marine incursion. The inferred paleoclimate ranged from savannah tom Rainforest as evidence from diagnostic palynoforms. Also, the paleoclimate, paleoenvironment and age of the penetrated strata of the basin indicate a good prospectivity potential for the basin though with prevalence of dry gas