ALPINE GEODYNAMIC EVOLUTION OF PASSIVE AND ACTIVE CONTINENTAL-MARGIN SEQUENCES IN THE TAUERN WINDOW (EASTERN ALPS, AUSTRIA, ITALY) - A REVIEW

The Penninic oceanic sequence of the Glockner nappe and the foot-wall Penninic continental margin sequences exposed within the Tauern Window (eastern Alps) have been investigated in detail. Field data as well a s structural and petrological data have been combined with data from t he literature in order to constrain the geodynamic evolution of these units. Volcanic and sedimentary sequences document the evolution from a stable continent that was formed subsequent to the Variscan orogeny, to its disintegration associated with subsidence and rifting in the T riassic and Jurassic, the formation of the Glockner oceanic basin and its consumption during the Upper Cretaceous and the Paleogene. These u nits are incorporated into a nappe stack that was formed during the co llision between a Penninic Zentralgneis block in the north and a south ern Austroalpine block. The Venediger nappe and the Storz nappe are ch aracterized by metamorphic Jurassic shelf deposits (Hochstegen group) and Cretaceous flysch sediments (Kaserer and Murtorl groups), the Eclo gite Zone and the Rote Wand-Modereck nappe comprise Permian to Triassi c elastic sequences (Wustkogel quartzite) and remnants of platform car bonates (Seidlwinkl group) as well as Jurassic volcanoclastic material and rift sediments (Brennkogel facies), covered by Cretaceous flyscho id sequences. Nappe stacking was contemporaneous to and postdated subd uction-related (high-pressure) eclogite and blueschist facies metamorp hism. Emplacement of the eclogite-bearing units of the Eclogite zone a nd the Glockner nappe onto Penninic continental units (Zentralgneis bl ock) occurred subsequent to eclogite facies metamorphism. The Eclogite zone, a former extended continental margin, was subsequently overridd en by a pile of basement-cover nappes (Rote Wand-Modereck nappe) along a ductile out-of-sequence thrust. Low-angle normal faults that have d eveloped during the Jurassic extensional phase might have been inverte d during nappe emplacement.