A deep seismic sounding investigation of lithospheric heterogeneity and anisotropy beneath the Iberian Peninsula

• Published in: Tectonophysics Vol. 221; no. 1; pp. 35 - 51
• Main Authors: Díaz, J., Gallart, J., Córdoba, D., Senos, L., Matias, L., SuriÑach, E., Hirn, A., Maguire, P.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: London Elsevier B.V 30.04.1993; Amsterdam Elsevier Science; New York, NY
• Subjects: Applied geophysics; Earth sciences; Earth, ocean, space; Exact sciences and technology; Internal geophysics; Iberian Peninsula; geotraverses; models; reflection methods; velocity structure; anisotropy; lithosphere; upper mantle; elastic waves; layered materials; deep seismic sounding; arrival time; heterogeneity; refraction methods; tectonic maps
• ISSN: 0040-1951; 1879-3266
• DOI: 10.1016/0040-1951(93)90026-G

The dimensions of the Iberian Peninsula, the facility of firing large charges in the surrounding waters, the well-known and relatively uniform geology, and prior knowledge of the crustal structure, resulted in it being chosen as a study area for the investigation of the seismic structure of the lower lithosphere via refraction-wide-angle reflection seismic profiling. The Iberian lithosphere Heterogeneity and Anisotropy experiment (ILIHA), with a star-shaped arrangement of six long-range DSS profiles, was carried out in October 1989. The models derived from a first interpretation of the recorded data are presented. Three crustal profiles cover the same western and central part of the Hercynian Massif as the mantle profiles. The resulting interpretations all include a middle as well as a lower crustal layer above the mantle. The velocities of the layers in all three models are similar; however, the layer depths vary beneath the profiles. Interpretation of the mantle derived data suggests a layered lower lithosphere. One reversed line and an intersecting unreversed line indicate the layering penetrates to at least 90 km depth. The homogeneity of these layers contrasts strongly with the heterogeneous Hercynian surface geology. Velocities derived from reflected data from the deep layers suggest the constituent materials are either anisotropic or that the layers suffer a slight regional dip.