Hunting the European-Adriatic plate boundary in Eastern Alps: a receiver function perspective

The type of collision between the European and the Adriatic plates in the easternmost portion of the Alps is one the most intriguing questions regarding the Alpine evolution. The interaction between the two plates is controversial all along the Alpine chain, e.g. changes of subduction polarity have been argued, but never clarified. This study focuses on the crust-mantle boundary, and on the differences between the European and Adriatic plate structures along a North-South oriented Receiver-Function profile from the Bohemian Massif to the Adriatic Sea. A seismically anisotropic layer is observed on top of the Moho interface from the Adriatic Sea to one of the major tectonic lines of the area, the SEMP fault. A seismically anisotropic upper mantle is detected at the boundary of the two plates, belonging to Europe and downgoing beneath Adria. These anisotropic features witness a different response to deformation of the two plates. The plate boundary appears to extend further north than the recognized boundary on surface, raising new questions on the deep interaction between the two plates.