Designation Of The Standard Stratotype And Age Of Nsukka Formation Of Anambra Basin, Southeastern Nigeria

Abstract

The type locality of Nsukka Formation was designated north of Nsukka in an area along Nadu River, without any formal description of the type section. Field mapping of the type locality was undertaken with the intention to formally define the type section. The thickest and best exposed is a 40 meter thick, stream section at Ugwu Nkalagu-Obukpa, designated the unit stratotype, and complemented by the road section at Umulolo near Okigwe as the hypostratotype. The unit stratotype contains coal towards the base and falls within the lower shaly facies of the formation. The hypostratotype belongs to the top facies without coal, having at the base ca. 0.8 m thick coquina sandstone. The palynomorphs of the type section indicate paralic sedimentation while at the complementary section marine conditions prevailed and continued across the K/T boundary into the Paleocene. The formation dates Late Maastrichtian at the type section and Paleocene (Danian) at the hypostratotype where a sharp boundary with overlying Imo Formation.

Journal of Mining and Geology Vol. 43 (2) 2007: pp. 147-166