Structural development of high-pressure metamorphic rocks on Syros island (Cyclades, Greece)

New data obtained during re-mapping of the northern part of Syros (Cyclades, Greece) allow the refinement of existing concepts about the structural evolution of this island. A metabasite belt and its metasedimentary envelope near Kampos and San Michali were mapped at a 1:5000 scale, with special emphasis on the structural inventory. The HP/LT rocks (P∼1.5 GPa; T∼500 °C at ∼50 Ma) exposed are intensely deformed by at least two isoclinal folding events. Relative age relations between deformation and peak metamorphism indicate that isoclinal folding took place before or during peak metamorphism. Later deformation stages include Miocene non-penetrative upright kink folding and crenulation, transpressional strike-slip faulting, and open upright cylindrical folding, followed by the development of steep normal faults. Taking into account recent zircon U–Pb geochronological constraints, lithostratigraphic observations, and published data on the Neogene structural evolution of the Aegean, we present a history for the rocks of Syros, beginning with the formation of the oceanic crust (represented by the metabasites) to the present.