Evidence for a developing plate boundary in the western Mediterranean

Acknowledgements The authors acknowledge support from the Spanish Ministry of Economy and Competitiveness through the Complementary Action ESF TopoEurope TOPOMED (CGL2008- 03474-E/BTE) and national project EVENT (CGL2006-12861-C02-02). L.G.P. was funded by the Spanish Ministry of Education, Culture and Sport through the FPU fellowship AP2012-1579 and a Short-Term Scientific Mission (COST-STSM-ECOST-STSM-ES1301- 180814-045667) inside the COST Action ES1301. This study benefited from a Marie Skłodowska-Curie Individual Fellowship to L.G.P. (H2020-MSCA-IF-2017 796013), the project “MORPHOMED” (PID2019-107138RB-I00) funded by MCIN/SRA (State Research Agency/10.13039/501100011033), FEDER/Junta de Andalucía-Consejería de Transformación Económica, Industria, Conocimiento y Universidades/Projects (B-RNM-305-UGR18, A-RNM-508-UGR20 and P18-RT-3632), and acknowledges the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S) and C.R.R. project PID2019-109559RB-I00 of the Spanish “Ministerio de Ciencia e Innovación”.We thank the reviewers (JoaoDuarte and anonymous) for their insightful comments. This work has been carried out within Grup de Recerca Consolidat de la Generalitat de Catalunya “Barcelona Center for Subsurface Imaging” (2017 SGR 1662).Additional information Supplementary information The online version contains supplementary material available at https://doi.org/10.1038/s41467-022-31895-z.The current diffuse-strain model of the collision between Africa and Eurasia in the western Mediterranean predicts a broad region with deformation distributed among numerous faults and moderate-magnitude seismicity. However, the model is untested because most deformation occurs underwater, at poorly characterized faults of undetermined slip. Here we assess the diffuse-strain model analysing two active offshore fault systems associated with the most prominent seafloor relief in the region. We use pre-stack depth migrated seismic images to estimate, for the first time, the total Plio-Holocene slip of the right-lateral Yusuf and reverse Alboran Ridge structurally linked fault system. We show that kinematic restoration of deformational structures predicts a slip of 16 ± 4.7 km for the Alboran Ridge Fault and a minimum of 12 km for the Yusuf Fault. Thus, this fault system forms a well-defined narrow plate boundary that has absorbed most of the 24 ± 5 km Plio-Holocene Africa-Eurasia convergence and represents an underappreciated hazard.MCIN Projects A-RNM-508-UGR20, B-RNM-305-UGR18, P18-RT-3632H2020 Marie Skłodowska-Curie Actions H2020-MSCA-IF-2017 796013, PID2019-107138RB-I00Society for Research on AdolescenceGeneralitat de Catalunya 2017 SGR 1662Ministerio de Educación, Cultura y Deporte AP2012-1579, COST-STSM-ECOST-STSM-ES1301-180814-045667, ES1301 MECDMinisterio de Economía y CompetitividadMinisterio de Ciencia e InnovaciónSevero Ochoa Centre of Excellence CEX2019-000928-S, PID2019-109559RB-I0

Seismic structure of the St. Paul Fracture Zone and Late Cretaceous to Mid Eocene oceanic crust in the equatorial Atlantic Ocean near 18°W

Plate tectonics characterize transform faults as conservative plate boundaries where the lithosphere is neither created nor destroyed. In the Atlantic, both transform faults and their inactive traces, fracture zones, are interpreted to be structurally heterogeneous, representing thin, intensely fractured, and hydrothermally altered basaltic crust overlying serpentinized mantle. This view, however, has recently been challenged. Instead, transform zone crust might be magmatically augmented at ridge-transform intersections before becoming a fracture zone. Here, we present constraints on the structure of oceanic crust from seismic refraction and wide-angle data obtained along and across the St. Paul fracture zone near 18°W in the equatorial Atlantic Ocean. Most notably, both crust along the fracture zone and away from it shows an almost uniform thickness of 5-6 km, closely resembling normal oceanic crust. Further, a well-defined upper mantle refraction branch supports a normal mantle velocity of 8 km/s along the fracture zone valley. Therefore, the St. Paul fracture zone reflects magmatically accreted crust instead of the anomalous hydrated lithosphere. Little variation in crustal thickness and velocity structure along a 200 km long section across the fracture zone suggests that distance to a transform fault had negligible impact on crustal accretion. Alternatively, it could also indicate that a second phase of magmatic accretion at the proximal ridge-transform intersection overprinted features of starved magma supply occurring along transform faults. Key Points: - Seismic structure along the St. Paul fracture zone reflects magmatically accreted oceanic crust - Oceanic crust across St. Paul shows only small thickness variations, lacking evidence for regional crustal thinning near fracture zones - Magmatic nature of crust supports a mechanism where transform crust is augmented before being turned into a fracture zon

A tribute to Marie Tharp: Mapping the seafloor of back-arc basins, mid-ocean ridges, continental margins and plate boundaries

European Geosciences Union (EGU) General Assembly 2020, 4-8 May 2020Marie Tharp (1920-2006) was a pioneer of modern oceanography. She was an American geologist and oceanographic cartographer who, together with his husband Bruce Heezen, generated the first bathymetric map of the Atlantic Ocean floor. Tharp's work revealed the detailed topography and geological landscape of the seafloor. Her work revealed the presence of a continuous rift valley along the Mid-Atlantic Ridge axis, causing a paradigm in earth sciences that led to the acceptance of plate tectonics and continental drift theories. Piecing maps together in the late 1940s and early 1950s, Marie and his partner Bruce Heezen discovered the 75.000 km underwater ridge bounding around the globe. By this finding, they laid the conclusion from geophysical data that the seafloor spreads from mid-ocean ridges and that continents are in motion with respect to one another¿a revolutionary geological theory at that time. Many years later, satellite images demonstrate that Tharp¿s maps were accurate. In this contribution, we focus on detailed bathymetric maps collected from year 1992 to today, which include bathymetric maps from diverse parts of the world. For instance, we will show a) Back-arc basins (i.e. the Bransfield Basin, Antarctica; and the North Fiji Basin, SW Pacific); b) Mid-ocean ridges and fracture zones (i.e. the MAR at the South of Azores, the MAR at the Oceanographer-Hayes, and the St. Paul Fracture Zone at the Equator), and c) Active tectonic structures from the Gulf of Cadiz and Alboran Sea, located at the Africa-Eurasia plate boundary (Gibraltar Arc). Regarding this last area, we will characterize the seafloor expression of the fault systems, as well as the subsurface structure of the faults in the Gulf of Cadiz and Alboran Sea. This zone is characterized by a moderate seismicity, mainly reverse and strike-slip focal mechanisms; although large historical (AD1755, AD1829) and instrumental earthquakes or large/great magnitude also occurred, such as the earthquakes of 1969, 1994, 2004 and 2016. In addition, the Gulf of Cadiz-Alboran Sea area is compartmentalized in different crustal domains, bounded by active strike-slip fault systems. We adopted a multi-scale approach, including morphological analysis of shipboard multibeam bathymetry, near-bottom bathymetry obtained with Autonomous Underwater Vehicles (AUVs) at a resolution of 1-2 m, and medium to deep penetration multi-channel seismic (MCS) data. Finally, we will also show a couple of videos from recent marine cruises in the Gibraltar Arc (SHAKE-2015 and INSIGHT-2018), both using state-of-the-art high-resolution marine technologie

Compressional tectonic inversion of the Algero-Balearic basin: Latemost Miocene to present oblique convergence at the Palomares margin (Western Mediterranean)

Interpretation of new multichannel seismic reflection profiles indicates that the Palomares margin was formed by crustal-scale extension and coeval magmatic accretion during middle to late Miocene opening of the Algero-Balearic basin. The margin formed at the transition between thinned continental crust intruded by arc volcanism and back-arc oceanic crust. Deformation produced during the later positive inversion of the margin offshore and onshore is partitioned between ~N50°E striking reverse faults and associated folds like the Sierra Cabrera and Abubacer anticlines and N10–20°E sinistral strike-slip faults like Palomares and Terreros faults. Parametric subbottom profiles and multibeam bathymetry offshore, structural analysis, available GPS geodetic displacement data, and earthquake focal mechanisms jointly indicate that tectonic inversion of the Palomares margin is currently active. The Palomares margin shows a structural pattern comparable to the north Maghrebian margins where Africa-Eurasia plate convergence is accommodated by NE-SW reverse faults, NNW-SSE sinistral faults, and WNW-ESE dextral ones. Contractive structures at this margin contribute to the general inversion of the Western Mediterranean since ~7 Ma, coeval to inversion at the Algerian margin. Shortening at the Alboran ridge and Al-Idrisi faults occurred later, since 5 Ma, indicating a westward propagation of the compressional inversion of the Western Mediterranean

Anandamide and 2-arachidonoylglycerol baseline plasma concentrations and their clinical correlate in gambling disorder

Introduction Different components of the endocannabinoid (eCB) system such as their most well-known endogenous ligands, anandamide (AEA) and 2-arachidonoylglycerol (2-AG), have been implicated in brain reward pathways. While shared neurobiological substrates have been described among addiction-related disorders, information regarding the role of this system in behavioral addictions such as gambling disorder (GD) is scarce.AimsFasting plasma concentrations of AEA and 2-AG were analyzed in individuals with GD at baseline, compared with healthy control subjects (HC). Through structural equation modeling, we evaluated associations between endocannabinoids and GD severity, exploring the potentially mediating role of clinical and neuropsychological variables.MethodsThe sample included 166 adult outpatients with GD (95.8% male, mean age 39 years old) and 41 HC. Peripheral blood samples were collected after overnight fasting to assess AEA and 2-AG concentrations (ng/ml). Clinical (i.e., general psychopathology, emotion regulation, impulsivity, personality) and neuropsychological variables were evaluated through a semi-structured clinical interview and psychometric assessments.ResultsPlasma AEA concentrations were higher in patients with GD compared with HC (p = .002), without differences in 2-AG. AEA and 2-AG concentrations were related to GD severity, with novelty-seeking mediating relationships.ConclusionsThis study points to differences in fasting plasma concentrations of endocannabinoids between individuals with GD and HC. In the clinical group, the pathway defined by the association between the concentrations of endocannabinoids and novelty-seeking predicted GD severity. Although exploratory, these results could contribute to the identification of potential endophenotypic features that help optimize personalized approaches to prevent and treat GD

New interpretation of the sedimentary infill of the San Pedro basin based on new seismic data (Dominican Republic offshore)

Los nuevos datos de sísmica de reflexión multicanal 2D adquiridos en la Cuenca de San Pedro (margen sudeste de la República Dominicana), junto con antiguos perfiles sísmicos reprocesados, han permitido llevar a cabo un detallado análisis y revisión de la estratigrafía sísmica. Los nuevos datos sísmicos aportan nuevas precisiones sobre la evolución de la cuenca sugiriendo un origen de al menos Eoceno Superior, en lugar de Mioceno. La nueva interpretación se basa en la correlación onshore-offshore de un nivel guía de abanicos bien desarrollado, con los eventos tectónicos constreñidos tierra y asociados a la colisión con los Bancos de las Bahamas con el arco isla el Eoceno Medio.New 2D multichannel seismic reflection data recorded in the San Pedro Basin (south-eastern margin of Dominican Republic,) combined with vintage seismic reflection profiles, have allowed a detailed analysis and review of the seismic stratigraphy. New data supply new constraints on the evolution of the basin and suggest at least an Upper Eocene origin instead of Miocene. The new interpretation is based on the onshore-offshore correlation of fan deposits with the main tectonic events constrained onshore and related with the collision of the Bahamas banks with the island arc in Middle Eocene ages.Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEpu