Ichnology of the Cenomanian-Turonian of the Calabar Flank, SE Nigeria

Abstract

Trace fossils are described for the first time from Cenomanian-Turonian rocks of the Calabar Flank, SE Nigeria. The rocks essentially consist of SW dipping shales intercalated with thin beds of calcareous mudstone. In places, marly limestone occurs as low ridges parallel to the strike of the sequence. Thalassinoides are common in the calcareous rocks. Another, less numerous trace fossil, is probably the borings of phoronid. Marine benthonic pelecypods and gastropods, although of low diversity, are common in the mudstone and are rare or absent in most of the shale intervals which contain planktonic and impoverished benthonic foraminifera. Ichnological analysis supported by palaeontological and sedimentologicic evidence suggest a depositional environment with fluctuating shallow, aerated and oxygen-deficient bottom conditions.