National Research Insititute of Astronomy and Geophysics (NRIAG), 11421, Helwan, Cairo, Egypt
Abstract. After the onset of plate collision in the Alps, at 32–34 Ma, the deep structure of the orogen is inferred to have changed dramatically: European plate break-offs in various places of the Alpine arc, as well as a possible reversal of subduction polarity in the eastern Alps have been proposed. We review body-wave tomographic studies, compare them to our surface-wave-derived model for the uppermost 200 km, and reinterpret them in terms of slab geometries. We infer that the shallow subducting portion of the European plate is likely detached under both the western and eastern (but not the central) Alps. The Alps-Dinarides transition may be explained by a combination of European and Adriatic subduction. This would imply that the deep, high-velocity anomaly (> 200 km depth) mapped by tomographers under the eastern Alps is a detached segment of the European plate. The shallower fast anomaly (100–200 km depth) can be ascribed to European or Adriatic subduction, or both. These findings are compared to previously proposed models for the eastern Alps in terms of slab geometry, but also integrated in a new, alternative geodynamic scenario that best fits both tomographic images and geological constraints.
How to cite. Kästle, E. D., Rosenberg, C., Boschi, L., Bellahsen, N., Meier, T., and El-Sharkawy, A.: Slab Break-offs in the Alpine Subduction Zone, Solid Earth Discuss. [preprint], https://doi.org/10.5194/se-2019-102, 2019.
Received: 31 May 2019 – Discussion started: 06 Jun 2019
We compare a set of tomographic models that image the upper mantle beneath the Alps and try to find evidence for a potential break off of the subducting European plate. We infer that break offs are likely to have happened all around the Alpine arc, but timing, exact location and interaction between European and Adriatic plate still difficult to assess.
We highlight the value of integrating different tomographic methods to obtain a more complete picture of the deep structures.
We compare a set of tomographic models that image the upper mantle beneath the Alps and try to...