Permian metamorphic event in the Alps

In addition to the well-known Variscan and Alpine orogenic cycles, a Permian thermal event occurred in the European Alps. The geodynamic background of this event is not well understood. Here we suggest that the event is a reflection of lithospheric thinning accompanied by magmatic underplating causing partial melting of the lower crust and low-pressure-high-temperature metamorphism. The event was terminated by Early Triassic opening of the Meliata ocean and was followed by sag-stage subsidence during slow lithospheric cooling. This last stage of the evolution allowed the onset of the Mesozoic marine evolution with the orogen-wide formation of Triassic carbonate platforms well known from the Dolomites and the Northern Calcareous Alps. The combined evidence for magmatism, metamorphism, and late subsidence identifies the Permian event of the Alps as an excellent example of underplating events suggested as a cause for low-pressure-high-temperature terrains worldwide.