Geology, paleoclimatology and laterite genesis in the Gada sector of the Trans-Saharan seaway in northwestern Nigeria

Sediments of Maastrichtian and Paleocene age, deposited in the Trans-Saharan seaway, indicate littoral tidal flat conditions predominating, with periodic extensions of more fully marine conditions over the area. An unconformity between the Maastrichtian and Paleocene is described.

Evidence is given of a climate becoming increasingly humid through the Maastrichtian and Paleocene, giving rise to increased rates of chemical weathering. This led to the deposition of marine limestones and oolitic ironstones when less clastic sediment was available. The oolitic ironstones were not, therefore, formed within a soil profile as various authors have claimed.