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22 pages, 9 figures, supporting information https://doi.org/10.1029/2021JB022629.-- Data Availability Statement: Seismic and gravity data were collected by Spanish R/V Sarmiento de Gamboa in 2018. High-resolution images of the data used in this article are available in Figshare public database (https://figshare.com/articles/figure/MCS-seismic-line-interpreted_pdf/14865480 and https://figshare.com/articles/figure/OBS_H-seismic-record-sections_pdf/14865483). The bathymetric grid is freely available as a.xyz file from the website of the EMODnet (https://www.emodnet-bathymetry.eu/) and Generic Mapping Tools (Wessel & Smith, 1995) was used in the preparation of this manuscript.-- This is a contribution of the Barcelona Center for Subsurface Imaging that is a Grup de Recerca 2017 SGR 1662 de la Generalitat de Catalunya ; The West Iberia margin is the focus of intense research since the 1980s, with some of the most exemplary geophysical cross-sections and drilling expeditions. Those data sets have been used to create conceptual models of rifting used as a template to interpret margins worldwide. We present two collocated ∼350 km long lines of multi-channel seismic (MCS) streamer data and wide-angle seismic (WAS) data collected across the Tagus Abyssal Plain (TAP). We use travel-times of first arrivals identified at WAS and reflected seismic phases identified at both WAS and MCS records to jointly invert for the P wave velocity (Vp) distribution and the geometry of a sediment unconformity, the top of the basement, and the Moho boundary. The Vp model shows that the TAP basement is more complex than previously inferred, presenting abrupt boundaries between five domains. Domain I under the foot of the slope and Domain III under the abyssal plain display Vp values and gradients of thin continental crust. In between, Domain II displays a steep Vp gradient and high Vp values at shallow depth that support that basement is made of exhumed partly serpentinized mantle. Domain IV and Domain V, further oceanward, have oceanic crust Vp structure. The new results support an unanticipated complex rift history during the initial separation of Iberia and America. We propose a geodynamic scenario characterized by two phases of extension separated by a jump of the locus of extension, caused by the northward propagation of the oceanic spreading center during the J-anomaly formation, which terminated continental rifting ; The Spanish Ministry of Science, Innovation and Universities funded the FRAME project (CTM2015-71766-R) and I. Merino Ph.D. (BES-2016-077786). M. Prada is supported by the Beatriu de Pinós postdoctoral programme of the Catalonia Government (2017BP00170). [.] With the institutional support of the "Severo Ochoa Centre of Excellence" accreditation (CEX2019-000928-S) ; Peer reviewed

11 pages, 7 figures, supplementary material https://doi.org/10.1016/j.epsl.2020.116480 ; The formation of Cenozoic mountain belts in the Mediterranean realm was preceded by tens of millions of years of subduction, forming volcanic arcs, and frontal contractional systems. In addition, subduction usually involves slab rollback and formation of oceanic backarcs. Although such structure must have influenced the orogeny of Mediterranean mountain belts, no active analog has been mapped with modern crustal-scale seismic methods. Here, we study the entire Calabrian subduction system to map the structure resulting from Tethys lithosphere subduction and slab rollback, in a process that must be akin to that operating during a phase of the formation of the Mediterranean orogenic belts. We present a crustal-scale cross section of the entire Calabrian subduction system obtained from on- and off-shore wide-angle seismic data. The 2D P-wave velocity section shows spatially abrupt (<5 km of profile distance) structural and petrological transitions from the Ionian sedimentary wedge and Calabrian arc, to the rifted NW Calabrian margin, where the Quaternary Aeolian arc is emplaced. The margin, then, transitions northwards into the Marsili backarc region, where exhumed mantle and localized volcanism occurred during its formation. This complex structure implies rapid temporal and spatial changes between magmatic and amagmatic processes, and between compressional and extensional regimes during the evolution of this subduction system. We find that some terranes involved in the Alpine orogeny share petrological and tectonic similarities with some domains of the Calabrian subduction system. Based on the results of this study we propose the Calabrian Arc system as an analog for the subduction structuration that preceded the formation of Alpine orogenic systems ; The CHIANTI survey was part of the HADES project funded by the Spanish MINECO (Ref # CTM2011-30400-C01 and CTM2011-30400-C02). [.] M. Prada is funded by the Beatriu de Pinós postdoctoral programme of the Government of Catalonia's Secretariat for Universities and Research of the Ministry of Economy and Knowledge (Ref # 2017BP00170)

19 pages, 8 figures, supporting information https://doi.org/10.1029/2020JB019854.-- Data Availability Statement. The WESTMED data are archived at PANGAEA repository (https://doi.pangaea.de/10.1594/PANGAEA.921252), GEBCO bathymetry grid (https://doi.org/10.5285/a29c5465‐b138‐234d‐e053‐6c86abc040b9), and SRTM bathymetry/topography grid (https://doi.org/10.5067/MEaSUREs/SRTM/SRTMGL1.003) ; In continental settings, seismic failure is generally restricted to crustal depth. Crustal structure is therefore an important proxy to evaluate seismic hazard of continental fault systems. Here we present a seismic velocity model across the Gibraltar Arc System, from the Eurasian Betics Range (South Iberian margin), across offshore East Alboran and Pytheas (African margin) basins, and ending onshore in North Morocco. Our results reveal the nature and configuration of the crust supporting the coexistence of three different crustal domains: the continental crust of the Betics, the continental crust of the Pytheas Basin (south Alboran Basin) and onshore Morocco, and a distinct domain formed of magmatic arc crust under the East Alboran Basin. The magmatic arc under the East Alboran Basin is characterized by a velocity structure containing a relatively high‐velocity lower crust (~7 km/s) bounded at the top and base by reflections. The lateral extension of this crust is mapped integrating a second perpendicular wide‐angle seismic profile along the Eastern Alboran basin, together with basement samples, multibeam bathymetry, and a grid of deep‐penetrating multichannel seismic profiles. The transition between crustal domains is currently unrelated to extensional and magmatic processes that formed the basin. The abrupt transition zones between the different crustal domains support that they are bounded by crustal‐scale active fault systems that reactivate inherited structures. Seismicity in the area is constrained to upper‐middle crust depths, and most earthquakes nucleate outside of the magmatic arc domain ; This work is supported by the Cluster of Excellence "The Future Ocean", within the framework of the Excellence Initiative by the Deutsche Forschungsgemeinschaft (DFG) on behalf of the German federal and state governments. Efforts benefitted from funding of the German Science Foundation (DFG Grants GR1964/12‐1, RA 925/2‐1+2‐2, and RE 873/17‐1). The TOPOMED cruise was part of the EUROMARGINS and TOPO‐EUROPE initiatives of the EUROCORES Programme of the European Science Foundation (ESF). This study benefitted from an EU Marie Skłodowska‐Curie Individual Fellowship to L. Gómez de la Peña (H2020‐MSCA‐IF‐2017 796013). The Spanish Science and Innovation Ministry funded C. R. Ranero through the project FRAME CTM2015‐71766‐R and G. Booth‐Rea through the project PID2019‐107138RB‐I00. This is a contribution of the Barcelona Center for Subsurface Imaging, Grup de Recerca 2017 SGR 1662, Generalitat de Catalunya ; Peer reviewed