Trace fossils from the Lower Jurassic Ciechocinek Formation, SW Poland

Mud-silt deposits of the Lower Jurassic Ciechocinek Formation from the Czestochowa-Wielun region are characterized by a low diversity ichnofossil association, which includes the ichnogenera Planolites, Palaeophycus, Helminthopsis, Gyrochorte, Protovirgularia and Spongeliomorpha as well as some unidentified pascichnia. This association points to deposition in a low-energy brackish environment with poorly oxygenated sediments. Changes of seafloor oxygenation, influenced by periodical bottom currents, resulted in various bioturbation intensities, which range from none to high.