| Summary: | 4th Fault2SHA Workshop, Fault Complex Interaction: Characterization and Integration into Seismic Hazard Assessment (SHA), 3-5 June 2019, Barcelona We present a new classification of geological domains at the Africa-Eurasia plate boundary off SW Iberia, together with a regional geodynamic reconstruction spanning from the Mesozoic extension to the Neogene-to-present-day convergence. It is based on seismic velocity and density models along two regional wide-angle seismic transects, combined with previously available information. The seismic velocity and density structure at the Seine Abyssal Plain (SAP) and the internal Gulf of Cadiz (GC) indicates the presence of a highly heterogeneous oceanic crust, whereas in the Horseshoe and Tagus abyssal plains, the basement structure resembles that of exhumed mantle sections identified in the Northern Atlantic margin. The integration of all this new information allows defining the presence of 3 oceanic domains off SW Iberia: (1) the SAP domain, generated during the first stages of slow seafloor spreading in the NE Central Atlantic (Early Jurassic); (2) the GC domain, made of oceanic crust generated in the Alpine-Tethys spreading system between Iberia and Africa, which was coeval with the formation of the SAP domain and lasted up to the North Atlantic continental break-up (Late Jurassic); and (3) the Gorringe Bank (GB) domain, mainly made of rocks exhumed from the mantle with little synchronous magmatism, which formed during the first stages of North Atlantic opening. Our models suggest that the SAP and GC domains are separated by the Lineament South strike-slip fault, whereas the GC and GB domains appear to be limited by a deep thrust fault located at the center of the Horseshoe Abyssal Plain. The formation and evolution of these 3 domains during the Mesozoic is key to understand the sequence of events that occurred during the first stages of opening of the Northern Atlantic Peer Reviewed
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