Kinematics and metamorphism of a cretaceous core complex: The veporic unit of the Western Carpathians

The Veporic basement and its Permian-Mesozoic cover experienced medium-pressure, collision-related metamorphism during the Cretaceous. Geothermobarometric calculations of Alpine mineral assemblages indicate peak conditions of 8–12 kbar and 550–600°C in the deepest-exposed basement, and up to 8 kbar and 450–500°C in the Permian metasediments. After having reached the metamorphic peak conditions (at around 110 Ma, ⁴⁰Ar/³⁹Ar on amphiboles), the thermally softened Veporic unit was exhumed probably due to the underplating of a buoyant Tatric-Fatric crust. Exhumation was triggered by extensional denudation of former upper-crustal thrust units, overlying the Veporic unit. Unroofing was accomplished due to orogenparallel, top-to-east extension along low-angle, ductile normal shear zones. The area collapsed and rapidly cooled at 90-80 Ma (⁴⁰Ar/³⁹Ar on micas). As revealed by the structural record, the doming and tectonic exhumation of the Veporic core occurred in an overall contractional regime and was followed by additional Late Cretaceous—Early Tertiary shortening events.