This project harnesses the high density of seismic stations in the AlpArray complementary experiment SWATH D, conducted during the first phase of SPP 2017 “Mountain Building Processes in 4D”, and also incorporates the wide EASI transect, in order to understand how the crustal structure seen today reflects the dramatic changes in mountain building style and reorganisation of plate boundaries at about 20 Ma. Uniform SE-directed subduction of European lithosphere during the Paleogene gave way to a more complex system involving not only the (partial) continuation of European subduction but the onset of Adriatic subduction below the Carpathians, the Apennines, and possibly the Alps. On the surface this revolution was reflected by laterally migrating subsidence patterns and infill in foreland basins as well as the development of different styles of accommodating shortening across the orogen. Within the crust, these changes must be accommodated by large scale decoupling horizons, but their geometry and relation to the structures seen at the surface, and even whether they are inside the crust or at the Moho, is disputed and probably differs laterally along the strike of the orogen. A still unresolved question concerns the existence of a possible polarity flip in the sense of subduction between the Central and Eastern Alps. If part of the continental crust is subducted, then a characteristic jump in the Moho is expected.

We have a clear focus on mapping the possible reorganisations within the crust and of the topography of the Moho. We also indirectly constrain the different scenarios of crustal evolution that could have led to the current structure. By including experts in both seismological analysis as well as Alpine geology and petrophysics of the continental crust, we aim to go beyond merely delivering images of seismic properties by associating lithological interpretations in a probabilistic way.

Time frame

• 2020 - 2024

Principal Investigators

• Frederik Tilmann (GFZ)
• Xiaohui Yuan (GFZ)

Doctorand/Staff

• Stefan Mroczek (GFZ)

Funding

• DFG im Rahmen des SPP 4DMB Phase 2

Project website

• spp-mountainbuilding

Cooperation/Partner

• Wolfgang Friederich (RU-Bochum)
• Timm John (FU-Berlin)
• Jan Pleuger (FU-Berlin)
• Sascha Zertani (Univ. Oslo)
• Emanuel Kaestle (FU-Berlin)

Allocation (POF/MESI/GIPP)

Topic 3 - Restless Earth

Publication

• Mroczek, S., Tilmann, F., Pleuger, J., Yuan, X., Heit, B. (2023): Investigating the Eastern Alpine–Dinaric transition with teleseismic receiver functions: Evidence for subducted European crust. - Earth and Planetary Science Letters, 609, 118096. https://doi.org/10.1016/j.epsl.2023.118096GFZPublic