Metasediments Covering Ophiolites in the HP Internal Belt of the Western Alps: Review of Tectono-Stratigraphic Successions and Constraints for the Alpine Evolution

Ophiolites of the Alpine belt derive from closure Mesozoic Tethys Ocean that was interposed between palaeo-Europe and palaeo-Adria continental plates. The orogeny has intensely reworked oceanic rocks into metaophiolites with various metamorphic imprints. In Western Alps, continental-derived units are distributed within two paired bands: An inner band where subduction-related high-pressure (HP) metamorphism is preserved, an outer blueschist to greenschist facies recrystallisation due decompression path prevails. hugely important not just because they provide records prograde tectonic evolution but also retain signature intra-oceanic tectono-sedimentary evolution. Lithostratigraphic petrographic criteria applied metasediments associated HP reveal occurrence distinct tectono-stratigraphic successions including quartzites marbles, chaotic rock units, layered calc schists. These successions, although sliced, deformed, superposed in complex ways during orogenic stage, preserve remnants their primary depositional setting constraining pre-orogenic Jurassic Ocean.