Trace fossils and depositional environments in the Hawaz Formation, Middle Ordovician, western Libya

Trace fossils from the Lower Muschelkalk of Raciborowice Górne (North Sudetic Synclinorium, SW Poland) and their palaeoenvironmental interpretation

“…Bromley and Ekdale (1984) interpret Thalassinoides as structures left on a shelf by big arthropods. Thalassinoides in Palaeozoic strata might have been constructed by trilobites, other arthropods, enteropneust worms, ancestors of decapods or unidentified organisms (Gouramanis et al 2003;Cherns et al 2006;Gibert et al 2011;. In non-marine environments the most likely producers are decapod crustaceans and crayfish (Kim et al 2002).…”

“…Thalassinoides occurs from the Cambrian (Miller and Byers 1984;Mikuláš 2000;Gibert et al 2011;Hofmann et al 2011) to the Holocene (Sheehan and Schiefelbein 1984;McCann and Pickerill 1988). It becomes abundant in the Ordovician (Myrow 1995;Ekdale and Bromley 2003;Pruss and Bottjer 2004;Jin et al 2011;Phillips et al 2011).…”

“…Polychaetes, sipunculans and barnacles are the most typical tracemakers of Trypanites weisei Knaust 2007a;Checconi et al 2010;Gibert et al 2011;Bassi et al 2013). …”

The Ediacaran–Cambrian and Ordovician rocks of Al Qasim Province, Saudi Arabia: Facies, depositional history and regional correlation

“…The bioturbated sand-flat facies reflects environments located between the shoreline and shoaling area beyond which sedimentation was storm dominated (Jean-Francois et al, 2007). The Skolithos ichnofacies in the Hawaz Formation (Middle Ordovician), western Libya is related to shallow marine settings and to regressive sand belts prograding during high-stand sea level conditions (Gibert et al, 2011). Though most of the Skolithos-generated piperocks are classically attributed to storm-dominated nearshores, tidal influences are suggested by frequent tidally-bundled , migrating bedform (Nio and Yang, 1991).…”

“…In the Middle Ordovician Hawaz Formation, in western Libya, In transgressive facies are dominated by horizontal burrows and trails, characteristic of the Cruziana ichnofacies. Higher diversity is achieved in those heterolithics found as forming part of the storm-dominated facies association, while similar facies associated to tidal deposits exhibit a less variety and abundance of traces indicating less favorable ecological conditions(Gibert et al, 2011). Muddy interbeds reflects post-storm deposition of fine material and/ or fair weather conditions(Jean-Francoie et al, 2007) …”