The palaeoenvironment of deposition of Late Maastrichtian to Paleocene black shales in the eastern Dahomey Basin, Nigeria

Abstract

Extensive black shale facies of Late Maastrichtian to Paleocene age are associated with the equally widely distributed tar sand sequence in the Nigerian sector of the Dahomey Basin. The shales are commonly finely laminated and are rich in organic carbon. They contain an abundance of pyrite and have yielded a rich faunal assemblage indicating shallow water conditions. The co-occurrence of abundant benthos, pyrite and enhanced organic carbon contents in the shales suggests an overall euxinic depositional palaeoenvironment that was episodically oxygenated.