(1) Geophysical Institute, Academy
of Science of the Czech Republic, Prague
(2) EOST - Institut de Physique du
Globe Strasbourg, France
We studied lithospheric structure of the MC and BM, two Variscan units which have been reactivated by rifting and Tertiary volcanism. P-velocity tomography, geodynamic modelling, and geochemical characteristics of the volcanic activity provide an evidence for the ascent of a mantle plume beneath the MC. The seismic data have been reprocessed in order to compute P-residual spheres which together with shear-wave splitting measurements led to anisotropic structural model. Such 3D self-consistent model confirms that the MC is built by two different juxtaposed lithospheric domains of different structure separated by a zone comprising the Limagne Graben and Sillon Houiller fault. Seismic data recorded recently in the BM are used to build a tomographic model as well as to show different orientations of anisotropic structures within the southern (Moldanubian) and the northwestern (Saxothuringian) parts. The change in orientation patterns relates to the Eger Graben and its continuation to the west. These results, as well .as results from other regions, suggest that the lithosphere consists of tectonic domains of different origin, structure and age, characterized by large-scale dipping anisotropic structures.
Not available.