Subcrustal lithosphere around the Saxothuringian–Moldanubian Suture Zone — a model derived from anisotropy of seismic wave velocities

Abstract

We have modelled the thickness and large-scale fabric of the subcrustal lithosphere from the variations of P-wave delay times and the shear-wave splitting observed at seismological observatories and four mobile stations in central Europe. The Saxothuringian (S) lithosphere is characterized by a total thickness of 90–120km and by a coherent fabric in its mantle part with olivine (a,c) foliation planes dipping to the north–northwest. The Moldanubian (M) lithosphere is generally thicker — 120–140km, on the average, and characterized by (a,c) foliations dipping to the south. The divergently dipping anisotropic structures may represent remnants of successive paleosubductions of the ancient oceanic lithosphere “frozen” in the subcrustal lithosphere of both units a long time before their Variscan collision. The deep S/M contact is marked by a lithosphere thinning to about 80–90km beneath the S/M surface boundary. Within the subcrustal lithosphere, a complex structure of the transition of both units extends to about 150km toward the south as indicated by the anisotropic characteristics of body waves.