Lithosphere structure along the northern part of EUROBRIDGE in Lithuania; results from integrated interpretation of DSS and gravity data

In the summer of 1995, the first on-shore phase of the EUROBRIDGE DSS experiment took place in Lithuania. The quality of recordings was good and contained clear P-wave reflections from inter-crustal interfaces and the Moho boundary. Very clear reflections were also registered from the interface below the Moho boundary. The arrivals of both reflected and refracted P-waves from 10 shotpoints were processed using the seis83 ray-tracing program. As a result, a 2-D seismic model along the Lithuanian part of EUROBRIDGE has been obtained. The comparison of synthetic and experimental seismograms showed good agreement of the model with registered travel times. To visualise better the existing tectonic discontinuities, an integrated 2-D seismic and density model along the northern part of EUROBRIDGE was compiled. For this purpose, the technique of gravity data inversion based on a non-linear relationship between density and seismic P-wave velocity was used. This integrated velocity–density model helped to reveal differences in deep lithosphere structure beneath the northern part of EUROBRIDGE where the tectonic contact of two Proterozoic terrains is located.