Old domains in the South Adria plate and their relationship with the West Hellenic front

The compactness and continuity of the Apulia carbonate platform, outcropping on the Salento penin-sula, contrasts with the structural complexity that developed during the Mesozoic–Miocene in the mostsouthern region, which was later affected by the Neogenic compression of the Calabrian and HellenicChains. Although the north-eastern margin of the Apulia carbonate platform has been clearly definedby seismic profiles in the South Adriatic basin, the identification of the southern platform margin andthe transition between the Apulia and Pre-Apulia units are more difficult. Our analysis, based on seismicfacies interpretation, suggests a complex trend of a reefal margin between the carbonate platform and anewly recognized deep basin, herein called as the South Apulia basin. This margin transversely crossesthe Otranto Channel from the Apulian coast, where it outcrops, to the Albanian/Greek coasts, where theplatform sinks below the Albanian/Hellenic Chain. The South Apulia basin originated from an extensionalphase that was probably active during the Jurassic. Furthermore, this pelagic sequence depicts a troughthat was almost partially separating the Apulia from the Pre-Apulia units, these last being widely exposedon the Ionian islands of Greece.The alternation of pelagic and differently evolved carbonate platform domains of the South Adria plateaffected the westward migration of the Hellenic Arc quite significantly. The thinner fractured foreland,which is characterized by pelagic sequences, is more suitable for underthrusting the chain, as does theSouth Apulia basin below the Corfù external front. In contrast, the thicker foreland sectors, which areassociated with the carbonate platform, resist flexural subsidence, similar to the Apulia and Pre-Apuliacarbonate platform domains. At a certain location, the thick, less-heaving foreland, which is resistantto subsiding, was overcome by compressional stress and thrusted as the Apulia units in the Karaborunpeninsula/Sazani isle. In the Paxos island, the carbonate platform has been uplifted by a salt diapir thatwas triggered by the Hellenic compression.The Cephalonia system cuts the Hellenic Chain with right transpressional tectonics, in response to thedifferent buoyancies of the foreland sectors to the westernmost prolongation of the North Anatolia Fault.While on the northern sector, the front of the chain currently has stopped to the east of the Apulia car-bonate platform, on the southern sector, the Ionian oceanic foreland is subducting below the Pre-Apuliaunits, a previous foreland of the Ionian units. This shifting of the Hellenic front through the Cephaloniasystem (from the eastern margin of the Apulia carbonate platform to the western margin of the Pre-Apulia zone) has caused an apparent horizontal displacement that is greater than the actual throw of theoverriding sequences.