Structural and geochemical data on the Rio Magno Unit: evidence for a new ‘Apenninic’ ophiolitic unit in Alpine Corsica and its geodynamic implications

Abstract

The Rio Magno Unit (RMU) tectonically overlies the Schistes Lustrés units in south‐eastern Alpine Corsica. It is represented by an ophiolitic sequence, showing remarkable differences with respect to the commonly recognized Corsican ophiolites. This unit can be distinguished from the Schistes Lustrés by the lack of HP–LT metamorphism, reflecting its different geodynamic setting, although both were involved early in the same tectonic events. Similarly, the RMU can be distinguished from the Balagne Unit by the presence of normal‐MORB basalts and the scarcity of continent‐derived sedimentary input, testifying to a different oceanic palaeogeographical setting. Moreover, the petrochemical and stratigraphic features of the RMU ophiolitic sequence show close analogies with the Internal Ligurides of the Northern Apennines. The RMU represents the first record of a nonmetamorphic ‘Apenninic’‐type ophiolitic unit in Alpine Corsica, supporting the hypothesis that the Alpine Corsica – Northern Apennine system represents a double‐vergent accretionary wedge.