Timing of high-pressure metamorphic events in the Bulgarian Rhodopes from Lu–Hf garnet geochronology

摘要: Within the Mediterranean realm, Rhodopes represent a nappe stack of oceanic and continental fragments assembled along Eurasian margin during Alpine orogeny. The timing high-pressure (HP) metamorphism has long been ambiguous, lacking detailed geochronological geochemical control on subduction-exhumation stacking processes. Here we apply Lu–Hf Sm–Nd chronometers to suite representative eclogite samples covering two different key units Rhodopean stack: (1) Kimi Complex (Upper Allochthon) (2) Middle Allochthon. In addition geochronology, also determined whole rock Hf Nd isotope compositions as well major trace element concentrations in order constrain nature protoliths. Two HP metamorphic events were revealed by geochronology: Lower Cretaceous event Upper Allochthon (126.0 ± 1.7 Ma) an Eocene (44.6 ± 0.7 Ma; 43.5 ± 0.4 Ma; 42.8 ± 0.5 Ma), at conditions ca. 700°C/20–25 kbar. Our new data provide direct evidence for multiple subduction Rhodopes. Exhumation subsequent thrusting can be narrowed down time span between 42 34 Ma. broader tectonic context, ages support view that large-scale window, exposing deepest Hellenides.