Trace Fossils from the Campanian - Maastrichtian Enugu Formation of the Anambra Basin, South-eastern Nigeria: Implications for Paleoenvironmental Interpretation

The Enugu Formation is a member of the Nkporo Group, and forms part of the basal stratigraphic unit of the Anambra Basin in south-eastern Nigeria. The Enugu Formation has been the subject of many studies concerning stratigraphy [1], depositional environments [2; Onuigbo et al. [3], organic geochemistry [4-6], paleoecology [7], palynology [7-9] and ichnology [10]. Nwajide & Reijers [2] were the first to document the presence of some ichnofossils such as Planolites and Thalassinoides in the formation, but did not give any detailed descriptions of the trace fossils. Onuigbo & Okoro [10] made the first attempt at describing the distribution and significance of the trace fossils in the Enugu Formation. They reported the presence of some trace fossils such as Skolithos and Chondrites in association with Planolites, Thalassinoides and Teichichnus at the road cut near the flyover located 200 m from the NNPC filling station at Enugu along the Onitsha – Enugu expressway. However, the ichnofossil assemblage present were not properly described and documented. Their paleoenvironmental interpretation did not consider the lithofacies association of the ichnofossils present. Taxonomic descriptions and paleoecologic interpretation were also lacking. The purpose of this study therefore, is to describe the morphology of the various trace fossils, describe their mode of occurrence and interpret their paleoenvironmental significance by integrating ichnological and lithofacies data. The study area is bounded by the longitudes 7°25 ́E to 7°30 ́E and latitudes 6°25 ́N and 6°30 ́N. The study is limited to two outcrops located at: 200 m from NNPC filling station and Trans Ekulu junction, both along Onitsha – Enugu expressway (Figure 1).