Mantle fabric of western Bohemian Massif (central Europe) constrained by 3D seismic P and S anisotropy

New teleseismic data from a dense network of temporary and permanent seismic stations were analyzed to investigate large-scale fabric of the lithosphere–asthenosphere system beneath the western part of the Variscan Bohemian Massif. We study three-dimensional orientation and strength of seismic anisotropy and model a fabric of the mantle lithosphere from shear-wave splitting and directional terms of relative P residuals. Fast shear-wave polarizations have mostly E–W orientation and split-delay times δt are around 1.2 s, on average. Small but systematic changes of the fast S split polarizations show a difference at about 20° to 30° between the Teplá-Barrandian (TBU)/Moldanubian (MD) tectonic units and the adjacent part of the Saxothuringian (ST), and about 40° between two parts of the ST, separated by a suture identified in the upper crust by different authors and by other methods. On the other hand, P-velocity anisotropy clearly indicates three different orientations of fossil olivine fabrics with inclined axes of symmetry in the mantle lithospheres of three tectonic units (ST, TBU, MD). The seeming contradiction between the results of the two independent data sets can be explained by different 3D anisotropic models: one with hexagonal ‘slow’ symmetry axis b and divergently dipping (a,c) foliations (ST, MD) and the other with hexagonal or orthorhombic symmetry with dipping high-velocity lineation a (TBU). These 3D self-consistent anisotropic models are compatible for both the P- and S-anisotropy observables. Our results suggest that a directionally varying constituent of the anisotropic signal is “frozen” in the mantle lithosphere. Regional changes in seismic anisotropy thus map tectonic boundaries, which cut the whole lithosphere, though with shifted crustal and mantle parts (TBU). Depending on symmetry and orientation of fabrics of the lithosphere domains, lateral changes are reflected in either P-velocity anisotropy and/or shear-wave polarizations. About half of the shear-wave split-time delays with predominantly E–W polarization azimuths represent a constant anisotropic signal which we associate with an olivine preferred orientation due to present-day flow in the asthenosphere. Our study emphasizes the importance of combining different methods of analysis and using complementary data sets in the three-dimensional analysis of mantle fabrics.