Abstract

Biostratigraphy of the Runji Beau outcrops was investigated in order to characterize lithological beds and to determine the palynomorph assemblages, age, and paleoenvironment of deposition. Methodology employed involves standard palynological slide preparation processes such asdecarbonisation of the samples with dilute HCl, hydrofluoric acid digestion, sieved with 5µm mesh, oxidation with HNO3, heavy liquid separation of macerals using ZnCl2with density of 2.1g/cc,rinsed with ethanol, and mounting of the slides. Lithostratigraphy succession is composed of repetitive, bioturbated sandstone and claystone beds. The stratigraphic section belongs to Milfordiaspp. Acme Zone, dated Campanian on the basis of maximum occurrence ofMilfordia spp. and Milfordiajardinei.Other stratigraphically important forms present and used for the dating of the outcrops includeLongapertitesmarginatus, Trichotomosulcitessp., Echitriporitestrianguliformis, Crototricolporitescrotonoisculptus, Syncolporites subtilis, Proteaciditessp., Retidiporitesmagdalenensis, andCingulatisporitesornatus.The Runji Beau sediments are equivalent to Wurno Formation, dated Campanian age, deposited in a fluviomarine setting based on the co-occurrence of terrestrially derived miospores, recovery of peridinacean type of organic wall organisms such as Senegalinium spp., Andalusiellapolymorpha, Florentinia sp., Phelodiniumbolonienae, and algae forms such as Pediastrum sp., and Botryococcusbraunii. The age of Wurno Formation deduced here is Campanian, different from the Paleocene age given by earlier researchers, thus, the Wurno Formation is suggested not to belong to the stratigraphic nomenclature Rima Group (Paleocene) of the Sokoto Basin, Nigeria.