A newly discovered Pliocene volcanic field on the western Sardinia continental margin (western Mediterranean

A previously unknown submerged volcanic field offshore western Sardinia, western Mediterranean Sea,has beenidentifiedbased on swath bathymetric data collected in November 2009, June 2010 and July 2013 and high-resolution seismic profiles collected in May 2011 and July 2013. About 40 conical-shapedvolcanic edifices (measuring an average width of about 400 m and average height of about 60 m) and wide (~1200 m)several lava outcrops (up to 1200 mwide) were recognized at 20 to 150 m water depth over an area of 800 km2. The volcanic edifices are mainly eruptive monogenic vents, mostly isolated with a rather distinct shape, or grouped to form a coalescent volcanic body in which single elements are often still recognizable. High-resolution seismics enabled identifying relationships between the volcanic bodies and continental margin successions. The edifices overlie a major erosion surface related to the margin exposure following the Messinian salinity crisis, and are overlain by anearly Pliocene marine sequence. This seismo-stratigraphic pattern dates the volcanic activity to the early Pliocene and isthus in agreement with the radiometric age for ofthe Catalano Islandlavas (4.7Ma) reported in earlier studies. The morphometry of the volcanic bodies suggests that cone erosion was higher at shallow water depths. Indeed, most of the shallow edifices are strongly eroded and flattened at 125to 130 m water depth, plausibly explained byrecurrent sub-aerial exposure during Pleistocene sea-level lowstands, whereas cones in deeper water are much better preserved. Volcanic vents and lava deposits, hereafter named the Catalano volcanic field (CVF),are emplaced along lineamentscorresponding to the main directions of the normal fault system that lowered the Sinis Basin and the western Sardinia continental margin. The CVF represents a volumetrically relevant phase of the late Miocene-Quaternary anorogenic volcanic cycle of Sardinia, which is related to the first stage of the extensional tectonics affecting the island since thelate Miocene.