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Anisotropic shear wave tomography of the european subcontinental lithospheric mantle


IPGP - Îlot Cuvier


Séminaires de Sismologie

Salle 310

Blanka Nita


The accretionnary history of the European continent is reflected in its terrane structure of hugely varying age. A very efficient way of investigating differences in physical parameters of those diversified tectonic provinces are seismic tomographic studies. In my talk, I will present the results of tomography studies undertaken with the aim of obtaining S-wave anisotropic structure of increased resolution compared to previous studies. A rich database of surface wave disperion data has been calculated from teleseismic events data for the aim of our modelling. The database includes Rayleigh as well as Love waves. Phase velocities of vertically polarised surface waves have been inverted at depth for retrieveing isotropic and anisotropic parameters. Taking into account the 36-200 s period range of surface waves enables us to model the deep subcontinental structure down to 300 km. After presenting a methodological approach, I will focus on the geological interpretation of the representative 2-D profiles cutting our 3-D model. Different anisotropy patterns are observed along the most distinctive feature on our maps - the bordering zone between the Palaeozoic and Precambrian Europe. I will focus on the depth changes of the lithosphere-asthenosphere boundary along the profiles crossing the chosen tectonic units of different origin and age: Fennoscandia, East European Craton, Anatolia, Mediterranean subduction zones. Within the flat and stable cratonic lithophere, we find traces of the mid-lithospheric discontinuity at a depth of about 80-100 km.