Tectonic Evolution of the Cycladic Blueschist Belt (Aegean Sea, Greece)

Abstract

The Cycladic blueschist belt comprises a number of tectonic units showing transitional paleogeographic affinities of a paleomargin from the carbonate platform of the external Hellenides to the Pindos-Cyclades oceanic basin. The blueschists were emplaced between the underlying los-Menderes crystalline basement plus its Mesozoic cover and the overlying non-metamorphic internal Hellenides (carbonate platform with the Axios-Vardar ophiolite nappe emplaced during Late Jurassic - Early Cretaceous during Late Eocene - Early Miocene. Several successive stages of the Cycladic blueschists can be detected, on the basis of metamorphic, structural and magmatic events, throughout their evolution from the Eocene subduction zone to the present situation behind the active volcanic arc. The internal structure of the blueschists is characterized by a radial distribution of fold hinges and co-parallel stretching lineations , probably representing a-structures, forming an amphitheatre with an overall tectonic transport from NE to SW, similar to the present plate-kinematics of the Hellenic arc and trench system.