Evidence of mud diapirism and coral colonies in the Ionian Sea (Central Mediterranean) from high resultion chirp sonar survey

A chirp sonar survey in the Ionian Sea investigated the Calabrian margin, the Calabrian accretionary wedge, the Taranto Trench and the Apulian foreland. Shallow tectonic structures have been related to deeper ones, recognised on CROP seismic profiles. The identified echo characters have been compared with those described in the modern literature and have been related to different kinds of sediments, on the basis of core samples. Based on echo character and morphology we have recognised: 1) A widespread presence of mounds, up to 50 m high, occurring on the Apulian plateau as isolated mounds in the deepest zones (1600-800 m) and in groups in the shallower ones (800-600 m); they have been interpreted as coral mounds, according to a recent discovery of living deep water coral colonies in this zone. 2) Some mud diapirs, isolated or in groups of two or three elements, widespread in the whole study area. Similar to what has been observed on the Mediterranean ridge, their presence suggests the activity of deep tectonic structures (thrusts and faults) and a reduced thickness (or absence) of Messinian evaporites in this part of the Ionian Sea.