A DEEP SEISMIC-REFLECTION SURVEY ACROSS THE BETIC CHAIN (SOUTHERN SPAIN) - 1ST RESULTS

Two land seismic reflection profiles across the Betic Chain have image d the deep structure of the crust belonging to two different crustal d omains. To the north, one profile samples the crust of the Variscan Ib erian Massif that underlies the sedimentary cover of both the Guadalqu ivir foreland basin and the South Iberian crustal domain. The upper cr ust is non-reflective along the profile, but the lower crust is reflec tive in the northern half of the profile between 7 and 12 s two-way tr avel time. In this segment of the profile the Moho is also well imaged . The quality of the data diminishes significantly as the profile ente rs 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 t he reflection Moho. Deeper reflections are also seen in the central pa rt of the profile in a segment about 10 km long. Comparison with avail able refraction and wide-angle reflection data shows some differences in both the crustal configuration and in the depth to the Moho.