Trace fossils from Maecuru Formation (Lower Devonian) of the Amazon Basin, and paleoenvironmental inferences

This paper discusses the trace fossil assemblage of the deposits of Maecuru Formation (Lower Devonian, Urupadi Group, Amazonas Basin, North of Brazil) exposed along the Trombetas River (Pará State, North of Brazil). The Maecuru Formation is composed of fine-grained sandstones and mudstones deposited in delta settings developed in shallow marine (neritic) environment subject to glacial incursions. Arthrophycus, Cruziana, Cymataulus, Lockeia, Palaeophycus, Rusophycus and two unidentified morphologies compose the trace fossil assemblage found in three outcrops. The ichnofauna occurs in sequences of massive body of fine-grained to medium-grained sandstones, in some cases showing lenticular geometry, with bed-parallel stratification, hummocky cross-stratification and climbing ripples. The trace fossil assemblage characterizes the Cruziana Ichnofacies and, together with the sedimentological features, suggests deposition in shallow, moderate to low-energy marine environment with wave influence, in a proximal shoreface.