CRUSTAL STRUCTURE OF THE CENTRAL SECTOR OF THE BETIC CORDILLERA (SE SPAIN)

Deep seismic reflection, gravimetric, and magnetometric data allow the main features of the deep structure of the central sector of the Beti c Cordillera to be established. The Moho is horizontal or dips slightl y toward the S below the mountain chain, and its morphology has no dir ect relationship with the region's topography. The deep reflectors are not deformed by the Neogene kilometric-scale folds that produced the main topographic features, probably due to the existence of detachment levels in the crust. The crust is slightly thickened in the Betic Cor dillera (almost 35 km) and has an abrupt transition to the thin crust of the Alboran Sea (15 km in the central Alboran Sea) along an E-W ori ented narrow band, subparallel to the coast line, where the Moho dips more than 60 degrees N. The Neogene evolution of the mountain chain ca used compressive deformation in the External Zones. In the Internal Zo nes, pre-Tortonian low-angle normal faults developed after the alpine metamorphism, and later high- and low-angle normal faults and strike s lip faults occurred up to the Quaternary. Geophysical and field geolog y data can be used to establish a geological model for the recent evol ution of the crustal deformation. In this model, the recent evolution of the region is probably determined by thrusting of the thin continen tal crust of the Alboran Sea toward the NW over the southern margin of the Iberian Massif. This deformation could be a consequence of the ob lique convergent movement between the African and Eurasian plates, whi ch may have uplifted the entire region, causing regressions in the sed imentary basins and the formation of folds and extensional structures in the upper part of the thickened crust.