Deep Tectonics in the Eastern Hellenides Uncovered: The Record of Variscan Continental Amalgamation, Permo‐Triassic Rifting, and Early Alpine Collision in Pre‐Variscan Continental Crust in the W‐Rhodope (Vertiscos‐Ograzden Complex, N‐Greece)

Abstract

AbstractThe Vertiskos‐Ograzden metamorphic complex (VOC; W‐Rhodope Metamorphic Domain, RMD) is a key area for reconstructing the geodynamic history of the Hellenides. We distinguish four metamorphic events: (1) an (U)HP eclogite facies metamorphism, succeeded by partial melting during decompression, amphibolite facies reequilibration in the kyanite stability field, and injection of muscovite pegmatites; (2) a LP‐HT event, associated with partial melting within the stability field of sillimanite, cordierite, and K‐feldspar (andalusite at subsolidus conditions) and magmatic intrusions; (3) a prograde moderate high‐pressure (MHP) metamorphism within the kyanite stability field increasing to the NE from epidote amphibolite to upper amphibolite facies; and (4) in the easternmost VOC, a LP amphibolite facies event (new cordierite and andalusite). Considering existing geochronological data, the VOC formed part of successive tectonic settings: (1) the “Variscan” collision zone between “East‐Avalonian” and Armorican continental fragments; (2) the Triassic middle crust of a continental rift zone, (leading to formation of oceanic crust, in the eastern VOC); (3) late Jurassic‐early Cretaceous closure of the oceanic basin and accretion of the VOC to southern European margin and northeastward polarity of subduction/collision; (4) late Cretaceous extension and crustal thinning. Then, subduction of the Neo‐Tethys and Apulian plate underneath Europe occurred, and the VOC plus the upper units of the RMD were part of the upper (European) plate. Large‐scale north dipping low‐angle normal detachments exhumed the VOC from the vicinity of a magmatic arc presently situated in the north RMD and Sredna Gora and Strandja zones and drag it into its present position.