Bioerosive structures on the Pliocene rocky shores of Catalonia (Spain).

Abstract

Bioerosive structures relating to rocky shores active during the Pliocene and associated pebbles in three basins at Baix Ebre Baix Llobregat and Alt Emporda areas (Catalonia, Spain) are reviewed. A high degree of uniformity exists behveen the basins from the ichnological point of view, although each one presents certain particular characteristics. The main bioerosive structures observed are the following: Entobia ichnospp.; borings of cheilostomata bryozoans of Spatipora and Terebripora types; Gastrochaenolites lapidicus and G. torpedo ; Meandropolydora ichnosp.; Centrichnus eccentricus ; Caulostrepsis taeniola and Caulostrepsis ichnosp.; Trypanites ichnosp.; Genatichnus pentax and bowl-shaped pits attibuted to regular echinoid activity. Apart from these bioerosive structures, the etching scars caused by cirripedes and epilithic bivalves are also common. The extensive presence of the Gastrochaenolites-Entobia ichnocenosis in Neogene rocky shores is emphasized.