Tectonics of the Syros blueschists (Cyclades, Greece): From subduction to Aegean extension

摘要: [1] On Syros, high-pressure metamorphism affects a lithological pile that is composed of, from base to top: (1) the Komito-Vari granitic basement, (2) margin sedimentary sequence predominantly made of marbles and schists (the Pyrgos Kastri units), (3) Kambos metaophiolitic melange. The tectonic history occurred in three main stages. During first stage, mid-Eocene, oceanic unit was thrust southward on top pile. Top-to-the-south-southwest ductile senses shear are synchronous with prograde associated this thrusting event. second stage corresponds top-to-the-northeast whole metamorphic retrogression eclogite greenschist facies. However, remained partly undeformed, as shown by significant volumes containing undeformed lawsonite pseudomorphs. No major extensional detachment related exhumation event outcrops island. localized semibrittle brittle deformation third postmetamorphic development ramp-flat system at island scale, whose minimum displacement estimated approximately 7 km, two sets steeply dipping strike-slip faults normal component, trending either east–west or around north–south, indicating mean stretching shortening directions NNE–SSW ESE–WNW, respectively. This events their relationship interpreted within framework subduction Pindos Ocean then Adria continental passive margin.