Compressional origin of the Aegean Orogeny, Greece

The Aegean Sea area is thought to be an actively extending back-arc region, north of the present day Hellenic volcanic arc and north-dipping subduction zone in Eastern Mediterranean. shows extensive normal faulting, ductile ‘extensional’ shear zones extensional S-C fabrics throughout islands that have previously been related regional extension associated with slab rollback on Subduction Zone. In this paper, we question interpretation, suggest Cenozoic geodynamic evolution region a Late Cretaceous–Eocene NE-dipping was responsible for continent-continent collision between Eurasia Adria-Apulia/Cyclades. Exhumation eclogite blueschist facies rocks Cyclades kyanite-sillimanite grade gneisses Naxos core complex pressures are far greater than could accounted purely by lithospheric isostatic uplift. We identify four stages crustal shortening affected prior extension, herein called Orogeny. This orogeny followed classic Wilson cycle from early ophiolite obduction (ca. 74 Ma) onto passive continental margin, attempted HP metamorphism 54–45 ​Ma), through thickening kyanite – sillimanite Barrovian-type 22–14 orogenic collapse (<14 ​Ma). At least three periods relate to: (1) blueschists showing tight-isoclinal folds top-NE, base-SW fabrics, recording return flow along channel compressional tectonic setting 50–35 (2) Extensional within complexes formed exhumation kyanite- thrust-related at base top 18.5–14 (3) Regional ductile-brittle low-angle faulting North Cycladic Detachment (NCD) South(West) (WCD) during flanks major NW–SE anticlinal fold middle Cyclades. Major faults show symmetry about area, NE chain (Andros, Tinos, Mykonos, Ikaria) exposing NCD consistent top-NE 200 ​km strike. contrast, Greek mainland (Attica) SE (Kea, Kythnos, Serifos) SW-dipping fault zone, WCD inferred 100 Islands deeper structural levels including sillimanite-grade metamorphic (Naxos, Paros) as well Variscan basement Ios). overall structure ~100 wavelength trending dome each flank, dipping away anticline axis SW. Many individual post-extensional large-scale folding around domes Paros, Ios, Sifnos) indicating post-Miocene late phase E–W shortening.