SUBDUCTION RELATED STRUCTURES IN THE NORTH IBERIAN MARGIN

The oblique convergence of Eurasia and Iberia since the Early Cretaceo us, caused the formation of the Pyrenean intracontinental collisional orogen in the east, and progressed to continent-ocean collision with s ubduction of the Bay of Biscay oceanic crust beneath the North Iberian Margin in the west: Two deep multichannel seismic profiles (IAM-12 an d ESCIN-4), integrated with gravity modeling and other geological and geophysical data, provide the crustal-scale architecture of this margi n and its tectonic evolution during the convergence. The North Iberian Margin is modeled with a south or south-southeast dipping oceanic cru st beneath the outer part of,the continental shelf. Mesozoic basins an the shelf were inverted during the Tertiary, and compressional activi ty continued until recent times in the ESCIN-4 section, while a shallo wer, probably Neogene age basin is subjected to active recent erosion in the IAM-12 section. In the oceanic areas, a marginal trough deepens and widens toward the east as a result of the regional east dip of th e oceanic basement. The:accretionary prism increases iri size from wes t to east (18-56 km), and its internal structure and morphology varies along Strike. The prism is buried by postconvergence sediments in bot h sections and in the IAM-12 section appears to have been active at le ast during Lutetian to Burdigalian times. The crustal-scale structure of the North Iberian Margin is that of an arrested subduction zone in which a remnant oceanic basin was being consumed near two continental plates that collided obliquely.