Alpine geodynamic evolution of passive and active continental margin sequences in the Tauern Window (eastern Alps, Austria, Italy): a review

Abstract

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 as structural and petrological data have been combined with data from the 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 Triassic and Jurassic, the formation of the Glockner oceanic basin and its consumption during the Upper Cretaceous and the Paleogene. These units are incorporated into a nappe stack that was formed during the collision between a Penninic Zentralgneis block in the north and a southern Austroalpine block. The Venediger nappe and the Storz nappe are characterized by metamorphic Jurassic shelf deposits (Hochstegen group) and Cretaceous flysch sediments (Kaserer and Murtörl groups), the Eclogite Zone and the Rote Wand-Modereck nappe comprise Permian to Triassic clastic sequences (Wustkogel quartzite) and remnants of platform carbonates (Seidlwinkl group) as well as Jurassic volcanoclastic material and rift sediments (Brennkogel facies), covered by Cretaceous flyschoid sequences. Nappe stacking was contemporaneous to and postdated subduc-tion-related (high-pressure) eclogite and blueschist facies metamorphism. Emplacement of the eclogite-bearing units of the Eclogite zone and the Glockner nappe onto Penninic continental units (Zentralgneis block) occurred subsequent to eclogite facies metamorphism. The Eclogite zone, a former extended continental margin, was subsequently overridden by a pile of basement-cover nappes (Rote Wand-Modereck nappe) along a ductile out-of-sequence thrust. Low-angle normal faults that have developed during the Jurassic extensional phase might have been inverted during nappe emplacement.

Correlated crustal and mantle deformation in the Tauern Window, Eastern Alps

“…Interior parts of the Tauern Window have been affected by multiple folding, too. Structural and kinematic data documenting this evolution have recently been published by Kurz et al (1994Kurz et al ( , 1998, , and Scharf et al (2013).…”

“…These indicate NNE-to NNW-directed kinematics during nappe detachment ( Fig. 1), being related to the formation of the Venediger Duplex Kurz et al, 1998;Schmid et al, 2013), with a general overview of kinematics of nappe stacking and shearing contemporaneous to amphibolite to greenschist facies metamorphism (Tauern crystallization), including kinematic data (after Neubauer et al, 1999). Nappe-stacking-related kinematics was reconstructed from maps and field data (for summary, see , and references therein).…”

“…This deformation is only developed penetratively in the upper structural level of the Venediger Nappe System, parts of the Seidlwinkl-Rote Wand Nappe in the central part of the Tauern Window, and within high-pressure mylonites of the Eclogite Zone (Kurz et al, 1998(Kurz et al, , 2004. During D1 a first penetrative foliation (s1) parallel to the thrust surfaces and a S-to SSEdipping apparent stretching lineation (l1) were developed.…”

“…Anisotropy in the upper mantle can be due to the strain field in the lithosphere and/or asthenospheric flow (Savage, 1999). Laboratory experiments have shown that the upper mantle is dominated by strongly anisotropic minerals (Maupin and Park, 2007). The origin of seismic anisotropy in the upper mantle is assumed to be related to the lattice-preferred orientation (LPO) of olivine due to dislocation creep (Mainprice et al, 2000;Karato et al, 2008).…”

Regional analysis of slope instability processes along the southern border of the central Tauern Window (Eastern Alps)

“…dominant fault planes that strike in WNW-ESE, NNW-SSE, N-S, NNE-SSW and NE-SE directions (pol plot and great circles in equal area projection, lower hemisphere, n. 86) with a high degree of separation are the main cause for large volume rockfalls (GMM 12 in Fig. 1) (mapping by Melzner, S., 2010).___________________________________ The region is located within the southern part of the central Tauern Window, which is characterized by high tectonic and lithological complexity (Kurz et al, 1998).…”