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Sample LOF 3/12 was crushed in a steel mortar. A representative aliquot was powdered in an agate mill for bulk rock analysis. A second split of the sample was sieved and the minerals were separated from a 355-500 μm size fraction using a Frantz magnetic mineral separator. Further garnet separation was obtained by hand picking under a binocular microscope. The garnet

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High-and ultrahigh-pressure rocks occur in the Austroalpine Nappes in a $400 km long belt from the Texel Complex in the west to the Sieggraben Unit in the east. Garnet growth during pressure increase was dated using Lu-Hf chronometry. The results range between c. 100 and 90 Ma, indicating a shortlived period of subduction. Combined with already published data, our estimates of metamorphic conditions indicate a field gradient with increasing pressure and temperature from the northwest to the southeast, where the rocks experienced ultrahigh-pressure metamorphism. The P-T conditions of the eclogites generally lie on the 'warm' side of the global range of subduction-zone metamorphic conditions. The oldest Cretaceous eclogites (c. 100 Ma) are found in the Saualpe-Koralpe area derived from widespread gabbros formed during Permian to Triassic rifting. In the Texel Complex garnets showing two growth phases yielded a Variscan-Eoalpine mixed age indicating re-subduction of Variscan eclogite-bearing continental crust during the Eoalpine orogeny. Jurassic blueschist-facies metamorphism at Meliata in the Western Carpathians and Cretaceous eclogite-facies metamorphism in the Austroalpine are separated by a time gap of c. 50 Ma and therefore do not represent a transition from oceanic to continental subduction but rather separate events. Thus, we propose that subduction initiation was intracontinental at the site of a Permian rift. K E Y W O R D S Eastern Alps, Eoalpine (Cretaceous) event, high-pressure metamorphism, thermodynamic modelling, Lu-Hf geochronology 1 | INTRODUCTION Two general scenarios have been proposed for the physical mechanism of nucleation of subduction zones:spontaneous, that is, caused by gravitational instability of oceanic lithosphere, and induced, that is, resulting from compressive stress acting on a plate (Stern, 2004). According to the prevalent view, subduction begins