High-pressure metamorphism in the Aegean, eastern Mediterranean: Underplating and exhumation from the Late Cretaceous until the Miocene to Recent above the retreating Hellenic subduction zone

[1] We report 40Ar/39Ar ages from various tectonic units in the Aegean and westernmost Turkey. On the basis of published geochronologic data and our 40Ar/39Ar ages we propose that the Aegean is made up of several high-pressure units, which were successively underplated from the Late Cretaceous until the Miocene. Ages for high-pressure metamorphism range from 80-83 Ma in parts of the Vardar-Izmir-Ankara suture zone in the north to 21-24 Ma for the Basal unit in the Cyclades and the external high-pressure belt on Crete in the south. Published seismic data suggest that high-pressure metamorphism is currently occurring underneath Crete. Younging of high-pressure metamorphism in a southerly direction mimics the southward retreat of the Hellenic subduction zone. We propose that distinct stages of high-pressure metamorphism were controlled by the underthrusting of fragments of mainly thinned continental crust and that these punctuated events were superposed on progressive slab retreat. By far most of the exhumation of the high-pressure units occurred early during the orogenic history in a forearc position.