Deep structure of the transition between the Cantabrian Mountains and the North Iberian Margin from wide-angle ESCI-N data

In the northern Iberian Peninsula, a N-S lithospheric transect along the Cantabrian Mountains and the continental margin can be constrained not only from the seismic images of the vertical reflection ESCI-N profiles but also from the analysis of complementary large-aperture reflection data. The seismic velocities interpreted from a refraction profile in the land segment confirma Variscan-type crust beneath the Duero basin, which has been reworked and thickened in the Cantabrian Mountains as a result of the Alpine tectonics. Forward modelling of high-quality wide-angle reflections, obtained by piggy-back recording onland the ESCI-N4 marine shots on 7 stations in a N-S line, indicates the existence of two different Moho levels. The deeper one is an "Iberian Moho" located in the sampled segment inland, strongly deepening northwards and defined up to the coast where it reaches about 60 km depth. A much shallower "Cantabrian margin Moho" is found in the marine segment, at depths ranging from 30 km beneath the coast to 22 km at the continental slope. The extend and location of this Moho is confirmed in a large-offset stacked section, obtained by multichannel processing of the wide-angle data. However, this technique cannot properly image the deeper Moho inland. The N-S seismic section that is built up by combining the different ESCI-N data sets suggests a wedge-type pattern of crustal subduction northwards, similar to the image given by the ECORS Pyrenees profile.