Control-Source Seismic Constraints on the Iberian Plate Structure: Insights into its Evolution and Deformation Processes (Invited)

Abstract

A large number of seismic transects have been acquired in Spain in the last ~40 years. These provided unique knowledge on the structure and nature of the Iberian lithosphere. Seismic imaging has unravel critical elements, e.g., the existence of orogen scale discontinuities that have resulted in controlling factors of Iberia¿s evolution. Control-source seismic data was first acquired in the early 80¿s across the Pyrenees. The resulting ECORS N-S transect constrained the internal architecture of the orogen, revealing changes in the deep reflection fabric that suggested the underthrusting of the Iberian crust below the European Plate. After ECORS, the ESCI programme was developed. Within this initiative, a number of transects targeted the N part of the Iberian Massif, the best exposed fragment of the European Variscides, and major Alpine orogens as the Betics. The former provided estimations of the Variscan accommodation of deformation and shortening, the effect of the opening of the Bay of Biscay and the imprint of the Alpine reactivation in the Cantabrian Mountains. The latter constrained the crustal thickness and the complexity of this young mountain belt located near a plate boundary. The Iberian margins were imaged by the VALSIS project in the Valencia Trough to the E of Iberia and, the IAM transects imaged the Atlantic margin to the W. These were complemented by seismic profiling in the southern and central part of the Iberian Massif. These were the IBERSEIS, ALCUDIA and CIMDEF, which characterize the crustal structure in an area where deformation was diachronous when compared with the N Iberian Massif. Furthermore, it contributed to understand the geometry of suture zones and the effects of important lower Carbonifeorus mantle upwelling in a zone later affected by transpression. These recent projects were an interdisciplinary scientific program promoted by EUROPROBE. All the datasets together result in a full transect across the Iberian Peninsula. With only some gaps in the northern Iberian, the above mentioned seismic reflection profiles have been critical to constrain the evolution and deformation of the Iberian Plate.