Ophiolite-bearing melanges in southern Italy

In southern Italy two ophiolite-bearing belts, respectively involved in the Adria-verging southern Apennines and in the Europevergingthrust belt of the northern Calabrian Arc, represent the southward extension of the northern Apennines and of ‘AlpineCorsica’ ophiolitic units, respectively. They form two distinct suture zones, which are characterized by different age ofemplacement and opposite sense of tectonic transport. The ophiolite-bearing units of the southern Apennines are represented bybroken formation and tectonic me´lange associated with remnants of a well-developed accretionary wedge emplaced on top ofthe Adria continental margin, with an overall NE direction of tectonic transport. These units consist of a Cretaceous-Oligocenematrix, which includes blocks of continental-type rocks and ophiolites with remnants of their original Upper Jurassic to LowerCretaceous pelagic cover. The innermost portion of the accretionary wedge is represented by a polymetamorphosed andpolydeformed tectonic units that underwent a Late Oligocene high pressure/low temperature (HP/LT) metamorphism. Thenorthern Calabria ophiolitic-belt is indeed composed of west-verging tectonic slices of oceanic rocks which, embedded betweenplatform carbonate units of a western continental margin at the bottom and the basement crystalline nappes of the Calabrian Arcat the top, are affected by a Late Eocene-Early Oligocene HP/LT metamorphism. The main tectonic features of these two suturezones suggest that they can be interpreted as the result of the closure of two branches of the western Neotethys separated by acontinental block that includes the crystalline basement rocks of the Calabrian Arc. We thus suggest that the north-east vergingsouthern Apennine suture constituted by a well-developed accretionary wedge is the result of the closure of a large Late Jurassic-Early Cretaceous oceanic domain (the Ligurian Ocean) located between the African (the Adria Block) and European continentalmargins. The northern Calabria suture derives indeed from the deformation of a very narrow oceanic-floored basin developedduring the Mesozoic rifting stages within the European margin separating a small continental ribbon (Calabrian Block) from themain continent.