An integrated study of the structure and thermomechanical properties of the European lithosphere

SUMMARY This Ph.D. thesis focuses on construction and analysis of a comprehensive model of the European lithosphere, which is based on the integration of most of the existing geophysical studies and estimation of physical (density, temperature, velocity) and rheological parameters. The model describes the structure and physical properties of the principal lithospheric layers, drawing special attention to their rheology. The objective of the research is reached through several steps. Chapter 1 describes the aim of this research and provides a review of the geodynamic evolution and the structural setting of Europe. Most of eastern Europe is dominated by the old, cold East European Craton (EEC), partly covered by the little deformed Phanerozoic and Meso-Neoproterozoic rift and platform successions. Western Europe, with some exceptions, is composed of thinner, warmer, dominantly Phanerozoic lithosphere, accreted to the EEC during Paleozoic and younger orogenesis. The European continent is affected by high seismicity, both in terms of frequency and magnitude, and vertical movements (uplift and subsidence), which are a direct expression of the current stress fields. The tectonic heterogeneity of Europe and the large number of geophysical investigations performed in the last years made this area an ideal place to perform the research project. Indeed, Europe is the locus of natural laboratories (e.g. the Alpine/Carpathians-Pannonian system, the Iberian Peninsula) comprising tectonic features (e.g. orogens, sedimentary basins) different for age and evolution. In Chapter 2 EuCRUST-07 is presented, a new high-resolution 3-D model of the European crust (35ºN-71ºN, 25ºW-35ºE), which is available from open sources The new model offers a starting point in any kind of numerical modelling, which has to resolve a trade-off between crustal and mantle effects. EuCRUST-07 was implemented assembling several hundred seismic profiles and receiver functions determinations (nearly all published data) and about 20 local compilations of the main crustal boundaries, basement and Moho depth. These data were analysed and cross-checked to select the most robust, before interpolating at a uniform 15'x15' grid using kriging method. The new model consists of three layers: sediments and two layers of the crystalline crust. Each layer of the crystalline crust is characterized by average P-wave velocities. EuCRUST-07 demonstrates large differences in the Moho depth compared to previous compilations, over ±10 km in some specific areas (e.g. the Baltic Shield). The basement is outcropping in some parts of eastern Europe, while in western Europe it is up to ~16 km deep, with an average value of …