Trace fossils from the turonian dukul and jessu formations in the yola arm of the upper Benue trough, ne Nigeria.

Abstract

The trace fossils Thalassinoides sp., Planolites sp. and Chondrites sp. are described from the Dukul and Jessu Formations in the Yola Arm of the upper Benue Trough. Thalassinoides sp. from the Dukul Formation occurs on the undersurfaces of marlstone and limestone beds.These units are dark gray in colour and contain sparse glauconite grains. The Jessu Formation contains networking Thalassinoides sp., horinzontal Planolites and branching Chondrites from micaceous and carbonaceous siltstones and fine grained sandstones. These trace fossil species belong to the Cruziana ichnofacies. The lithofacies characteristics, body fossils and the presence of the Thalassinoides sp. indicate that the Dukul Formation was deposited in a low energy oxygen- deficient open marine (mid-outer shelf) environment. The Jessu Formation was deposited in the mid-shelf to lower shoreface environment.

Journal of Mining and Geology Vol. 43 (2) 2007: pp. 187-196