Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published August 2001 | public
Journal Article

DAV and Periadriatic fault systems in the Eastern Alps south of the Tauern window

Abstract

Alpine deformation of Austroalpine units south of the Tauern window is dominated by two kinematic regimes. Prior to intrusion of the main Periadriatic plutons at ~30 Ma, the shear sense was sinistral in the current orientation, with a minor north-side-up component. Sinistral shearing locally overprints contact metamorphic porphyroblasts and early Periadriatic dykes. Direct Rb–Sr dating of microsampled synkinematic muscovite gave ages in the range 33–30 Ma, whereas pseudotachylyte locally crosscutting the mylonitic foliation gave an interpreted ^(40)Ar–^(39)Ar age of ~46 Ma. The transition from sinistral to dextral (transpressive) kinematics related to the Periadriatic fault occurred rapidly, between solidification of the earlier dykes and of the main plutons. Subsequent brittle–ductile to brittle faults are compatible with N–S to NNW–SSE shortening and orogen-parallel extension. Antithetic Riedel shears are distinguished from the previous sinistral fabric by their fine-grained quartz microstructures, with local pseudotachylyte formation. One such pseudotachylyte from Speikboden gave a ^(40)Ar–^(39)Ar age of 20 Ma, consistent with pseudotachylyte ages related to the Periadriatic fault. The magnitude of dextral offset on the Periadriatic fault cannot be directly estimated. However, the jump in zircon and apatite fission-track ages establishes that the relative vertical displacement was ~4–5 km since 24 Ma, and that movement continued until at least 13 Ma.

Additional Information

© 2001 Springer-Verlag. Received: 6 March 2000; Accepted: 15 November 2000; Published online: 15 March 2001. Thanks to A. Meier for help in dating the pseudotachylytes, and to B. Schulz and B. Cesare for introducing us to the Staller Satel and Hochhorn sections, respectively. Thanks also to L. Ratschbacher and B. Stöckhert for thorough and constructive reviews. Financial support for W. Müller from ETH grant 0-20-797-94, for B. Fügenschuh from ETH grant 0-20-479-91 and for G. Viola from ETH grant 0-20-211-96 is gratefully acknowledged.

Additional details

Created:
August 21, 2023
Modified:
October 20, 2023