Abstract

Geologically Europe is an ensemble of Phanerozoic and Precambrian terranes. Our work aims to understand the structure of the former collision zones of these terranes by imaging seismic discontinuities in the upper mantle. We used an improved version of the S-receiver function method without deconvolution and obtained high quality profiles through the study area. Below the Bohemian Massif, the southeastern Carpathians and Pannonian Basin and below the northern Apennines we found evidence for inclined velocity discontinuities below the lithosphereasthenosphere boundary reaching down to about 180 km depth. This might be interpreted as fossil subduction or delamination in collision zones in the Variscan area or ongoing subduction in the Alpine area. However, in the Vrancea seismic zone in the southern Carpathians this newly observed discontinuity does not agree with the near vertical distribution of the intermediate depth earthquake sources. A model of the structure below the Pannonian Basin and the Vrancea seismic zone might need to contain both, subduction and delamination.