Part of SSP 4D-MB Mountain Building in four dimensions
One of the prime goals of the SSP is to link surface geological observations with structures in the mantle. Our part is the interpretation of seismic S-receiver function data in terms of structure of the mantle below the Alps and surroundings. Previously we have studied the mantle structure in this region using data from the existing permanent seismic stations. The result of this study is that structures directly below the Alps are still relatively unclear. For this reason we will repeat our study adding all the newly collected data of the temporary seismic stations within the DFG project. However, we found in our preparatory study surprisingly complex structures below the Bohemian Massif and the Pannonian Basin in front of the northern boundary of the Alps. This is the region of germanotype tectonics defined by Hans Stille which is characterized by mainly vertical motions. It appears that our previous results suggest that the germanotype tectonics is not confined to the crust but extends into the mantle lithosphere.
The following figure shows an east-west S-receiver function profile through Bohemia. Blue signals are discontinuities with increasing velocities downward and read signals indicate velocity reductions downward. LABp stands for the Phanerozoic lithosphere-asthenosphere boundary (LAB) in the western part of Europe, MLD is the mid-lithospheric discontinuity and SLD (sub-lithospheric discontinuity) is the newly discovered north-west dipping deep discontinuity below the Bohemian Massif. LABc is the LAB of the east European craton. “Lehmann” stands for the Lehmann discontinuity, “LVZ” for a low-velocity zone on top of the discontinuity at 410 km depth, and “410” is the known discontinuity at that depth.