A deep seismic reflection survey across the Betic Chain (southern Spain): first results

Abstract

Two land seismic reflection profiles across the Betic Chain have imaged the deep structure of the crust belonging to two different crustal domains. To the north, one profile samples the crust of the Variscan Iberian Massif that underlies the sedimentary cover of both the Guadalquivir foreland basin and the South Iberian crustal domain. The upper crust is non-reflective along the profile, but the lower crust is reflective in the northern half of the profile between 7 and 12 s two-way travel time. In this segment of the profile the Mono is also well imaged. The quality of the data diminishes significantly as the profile enters the Neogene Guadix-Baza basin. A second profile crossing the Alpine metamorphic complexes of the Betics reveals a reflective lower crust and a conspicuous reflection in the upper crust that is continuous for about 10 km. At 11 s, a distinct reflection has been interpreted as the reflection Moho. Deeper reflections are also seen in the central part of the profile in a segment about 10 km long. Comparison with available refraction and wide-angle reflection data shows some differences in both the crustal configuration and in the depth to the Moho.