The structural and kinematic development of the Austroalpine-Pennine boundary, S.E. Tauern, Eastern Alps

Thesis



The Eastern Alps are a belt of major deformation formed by the convergence and collision of Europe with the Adriatic microcontinent. A major tectonic boundary can be defined between the dominantly continental Austroalpine domain, which represents the northerly fringe of Adria; and the Pennine oceanic domain, which once lay between the Austroalpine domain and Europe. This boundary is one of the key areas for unravelling the convergent tectonic history of the Eastern Alps. The main emphasis of this thesis is on the deformational behaviour of the Austroalpine domain and its implications for the regional tectonic processes that were instrumental in forming the structure of the Eastern Alps. The data for this work are derived from structural and metamorphic studies in the S.E. Tauern in profiles straddling the boundary, and a review of the published regional geology.

The first manifestation of convergence is the development of a broad zone of thickened crust, including both Pennine and Austroalpine units, which underwent Cretaceous burial metamorphism. Postdating this thermal event in the Austroalpine domain, there was a further phase of regional deformation, which caused substantial reduction in the structural thickness. To the south of the Tauern Window, a study of the associated kinematic development gives a minimum estimate of 10km for this thinning, which radiometric dating suggests took place while convergence was still active. A comparable 10km post-metamorphic thinning is suggested throughout the Austroalpine domain in the Eastern Alps by the shortfall in the overburden compared to the depth of burial indicated by the Cretaceous metamorphic conditions.

Major extension in a dominantly convergent tectonic setting cannot be accounted for by the paradigm of plate tectonics and implies that body forces acting on the thickened crust of the destructive margin were a major driving force for deformation.

Authors: Wallis, S; Wallis, Simon Richard

• Publication date: 1988
• DOI: 10.5287/ora-5rbppmapb
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Subjects: Rock deformation; Kinematics