Bioerosion structures from the Pliocene of the Agua Amarga Subbasin (Almería, SE Spain): Palaeoecological and palaeoenvironmental implications

The bioerosion trace fossils are described from the Pliocene cropping out at the Agua Amarga Subbasin (Betic Cordillera, Almería Province, SE Spain). They are associated with limestone clasts (pebbles and cobbles) and molluscs constituting a shallow marine conglomerate and an overlying composite shell bed that were deposited in a shallow marine setting. The ichnotaxa include borings produced by sponges (Entobia cateniformis, E. geometrica, E. laquea, E. form A and E. form B), bivalves (Gastrochaenolites torpedo, and G. lapidicus) and polychaete annelids (Caulostrepsis taeniola, Meandropolydora? decipiens, M. cf. elegans, and M. cf. sulcans). Encrustations by bryozoans and tube annelids are also present. The bioerosion trace fossils assemblages from the conglomerate and the shell bed can be ascribed to the Entobia subichnofacies, which is typical of Neogene rocky-shore settings. Bioerosion analysis allows improved interpretation of palaeoenvironmental (ecological and depositional) conditions i.e. hydrodynamic energy, rate of sedimentation, and exposure time, in the Agua Amarga Subbasin during the Pliocene.