Digital.CSIC. Repositorio Institucional del CSIC

oai:digital.csic.es:10261/232071

FRAME-MCS Cruise (29SG20180708) carried out on the Research Vessel Sarmiento de Gamboa in 2018, The nature and spatial distribution of geological domains across rifted continental margins are used to infer the processes that governed the formation of the system. Current conventional wisdom states that continental rifted margins formed away from the influence of hot-spots are systematically characterized by a spatial distribution of domains that implies a temporal sequence of geological events. The current paradigm proposes that extension of continental lithosphere causes thinning and break up of the crust leading to exhumation of the underlying mantle, followed by enough melting of the asthenosphere to form a spreading center. This widely accepted conceptual model is greatly influenced by past work in the West Iberia Margin, that is the model example of magma-poor rifted margins. However, the interpretation of the characteristics of the geological domains of the West Iberia Margin, including their nature (continental crust, synrift magmatism, oceanic crust etc), spatial distribution (e.g. width) and geometrical relationships (e.g. which occurred first) are for most of the region constrained by a few profiles of old-vintage, low-resolution geophysical data and locally restricted ground-truthing information. Based on our recent work, we propose that a considerable body of knowledge of the structure of the West Iberia continental margin needs to be updated with modern higher-resolution geophysical data, and the use of state-of-art methodologies to produce accurate quantifiable observations. Our recent work in the Gulf-of-Cadiz segment of the West Iberia Margin has shown that existing vintage data there provide ambiguous information, that cannot realistically constrain basement nature. Further, our work in the Tyrrhenian basin using several transects of modern seismic data has shown that the sequence of events accepted for the formation of rifted margins does not always apply, because there magmatic crust was formed before mantle exhumation. Therefore, a first main objective of this proposal is to collect, process, model with leading-edge methods and interpret several transects of geophysical data in key areas of the West Iberia Margin resulting from the separation of America from Iberia and African plates. Using those highly improved observation we aim at updating the characteristics of the geological domains of the rifted margin and refining existing conceptual models. As the second main objective of this proposal, we aim at analyzing the lithospheric-scale structures defined by the contacts among geological domains in the current kinematic framework of the region, where Africa and Iberian (Eurasian) plates are starting to collide. The Gulf-of-Cadiz segment of the West Iberia Margin is currently possibly entering into a new part of the Wilson cycle, in which structures formed by lithospheric deformation during basin opening are being re-activated with a different slip vector. The >100 Ma lithosphere is thick and lithospheric-scale faulting poses a major (albeit poorly studied and understood) hazard in the region. We aim at expanding our previous pilot work identifying and characterizing major lithospheric-scale boundaries, currently active and potentially capable of generating great seismic event of a magnitude similar to the catastrophic 1755 Lisbon earthquake and associated tsunami