Teresa Medialdea

Instituto Geológico y Minero de España

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Luı́s Somoza

Instituto Geológico y Minero de España

J.T. Vázquez

Instituto Español de Oceanografía

Javier González

Instituto Geológico y Minero de España

Ricardo León

San Francisco State University

Gemma Ercilla

Institut de Ciències del Mar

Desirée Palomino

Instituto Español de Oceanografía

Estefanía Llave

Instituto Geológico y Minero de España

Adolfo Maestro

Instituto Geológico y Minero de España

M.C. Fernández‐Puga

Universidad de Cádiz

David Casas

Institut de Ciències del Mar

Cooperative Institutions

Instituto Geológico y Minero de España

Consejo Superior de Investigaciones Científicas

Universidad Complutense de Madrid

Instituto Español de Oceanografía

University of Lisbon

Institut de Ciències del Mar

Universitat de Barcelona

Institut Català de Ciències del Clima

Universidade de Vigo

Universidad de Granada

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Morphostructure of the Galicia continental margin and adjacent deep ocean floor: From hyperextended rifted to convergent margin styles

Marine Geology (2018)

Luı́s Somoza Teresa Medialdea Javier González Ricardo León Desirée Palomino

Continental Margin

Passive margin

Seafloor Spreading

Margin (machine learning)

Submarine landslide

10.1016/j.margeo.2018.11.011

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Citations (16)

Morfología y tectónica del talud inferior del Golfo de Cádiz: implicaciones tectónicas y sedimentarias

Geotemas ( Madrid ) (2004)

J.T. Vázquez Teresa Medialdea Francisco Javier Hernández Molina Luı́s Somoza Víctor Díaz del Río

Analysis of bathymetric and seismic reflection data allow us to characterize the processes andstructures that generate seafloor morphological features in the lower continental slope and the transition to the abyssal plain of the Betic-Rif Margin. Several differences can be stablished in the lowerslope and the transition to the Horseshoe and Sena Abyssal Plains. The lower slope in the Horseshoe sector shows an upper convex - lower concave profile and the transition to the abyssal plainis marked by a scarp related to the activity of a main NE-SW reverse fault. Whereas in the Sena sector the lower slope appears as a convex profile and the region boundary with the abyssal plain isdetermined by the position of the external front of the Allochthonous Betic-Rif Units.

Abyssal plain

Seafloor Spreading

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Nature and tectonic setting of the Guadalquivier Bank (Gulf of Cadiz, SW Iberian Peninsula)

Revista de la Sociedad Geológica de España (2003)

Ramón Vegas Teresa Medialdea Mercedes Muñoz García Víctor Díaz del Río Luı́s Somoza

During two oceanographic cruises on the Guadalquivir Bank (continental slope of the southwestern Atlantic margin of the Iberian Peninsula), Variscan basement rocks were dredged, as well as, lithified hardground-related carbonate sediments containing Late Tortonian-Early Messinian foraminifers. Basement samples contained graywackes, shales, quartzites, basic volcanics, and metabasites in amphibolite facies. All these sedimentary and volcanic rocks can be attributed to the Volcano-Sedimentary Complex of the Pyrite Belt (South Portuguese Zone of the Iberian Variscan belt). This correlation is based on petrological similarities and the occurrence of low-grade metamorphism in prehnite-pumpellyite facies, identical to those defined in the Pyrite Belt. The metabasites have been correlated with the Beja-Acebuches Ophiolite Complex. These results have led us to consider two problems: the relationship between the Guadalquivir Bank and the South Portuguese Zone and the situation of this bank in the context of the Mesozoic evolution of the continental margin.The outcrop of these rocks on the middle slope of the Portuguese margin implies Variscan fold-and-thrust tectonics of greater intensity for the South Portuguese Zone, and the erosion of the Culm Group in the Guadalquivir Bank area. This erosion is explained by the uplift of the continental side of the transform fault that gave rise to the Mesozoic margin of the Southern Iberian Peninsula.

Continental Margin

Basement

Lithification

Outcrop

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Citations (9)

Adelgazamiento de la corteza en el margen septentrional del Golfo de Cádiz

Geotemas ( Madrid ) (2004)

Teresa Medialdea Diego Córdoba Ramón Vegas Juan José Dañobeitia

Refraction/wide angle seismic profiles acquired in 2000 during the Parsifal cruise across the Southportuguese Zone, the Algarve Basin and the South Iberian continental margin have allowed us to determine the crustal structure west of the Bank of Guadalquivir, which has been constrained by gravity modelling. According to the crustal model obtained, a crustal thinning of 11 km takes place from the shoreline to the Guadalquivir Bank area, where enhanced crustal attenuation has been found. Under the sedimentary cover, the velocity structure consists of a wedge-shaped upper crust with velocities between 5.8 and 5.9 km/s, characterised by a pronounced thickness variation. In the middle-lower crust, velocity increases from 6 to 7 km/s.

Continental Margin

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Hydrogenetic, Diagenetic and Hydrothermal Processes Forming Ferromanganese Crusts in the Canary Island Seamounts and Their Influence in the Metal Recovery Rate with Hydrometallurgical Methods

Minerals (2019)

Egidio Marino Javier González Thomas Kuhn Pedro Madureira Anna V. Wegorzewski

Four pure hydrogenetic, mixed hydrogenetic-diagenetic and hydrogenetic-hydrothermal Fe-Mn Crusts from the Canary Islands Seamount Province have been studied by Micro X-Ray Diffraction, Raman and Fourier-transform infrared spectroscopy together with high resolution Electron Probe Micro Analyzer and Laser Ablation Inductively Coupled Plasma Mass Spectrometry in order to find the correlation of mineralogy and geochemistry with the three genetic processes and their influence in the metal recovery rate using an hydrometallurgical method. The main mineralogy and geochemistry affect the contents of the different critical metals, diagenetic influenced crusts show high Ni and Cu (up to 6 and 2 wt. %, respectively) (and less Co and REY) enriched in very bright laminae. Hydrogenetic crusts on the contrary show High Co and REY (up to 1 and 0.5 wt. %) with also high contents of Ni, Mo and V (average 2500, 600 and 1300 μg/g). Finally, the hydrothermal microlayers from crust 107-11H show their enrichment in Fe (up to 50 wt. %) and depletion in almost all the critical elements. One hydrometallurgical method has been used in Canary Islands Seamount Province crusts in order to quantify the recovery rate of valuable elements in all the studied crusts except the 107-11H, whose hydrothermal critical metals’ poor lamina were too thin to separate from the whole crust. Digestion treatment with hydrochloric acid and ethanol show a high recovery rate for Mn (between 75% and 81%) with respect to Fe (49% to 58%). The total recovery rate on valuable elements (Co, Ni, Cu, V, Mo and rare earth elements plus yttrium (REY)) for the studied crusts range between 67 and 92% with the best results for Co, Ni and V (up to 80%). The genetic process and the associated mineralogy seem to influence the recovery rate. Mixed diagenetic/hydrogenetic crust show the lower recovery rate for Mn (75%) and Ni (52.5%) both enriched in diagenetic minerals (respectively up to 40 wt. % and up to 6 wt. %). On the other hand, the presence of high contents of undigested Fe minerals (i.e., Mn-feroxyhyte) in hydrogenetic crusts give back low recovery rate for Co (63%) and Mo (42%). Finally, REY as by-product elements, are enriched in the hydrometallurgical solution with a recovery rate of 70–90% for all the studied crusts.

Ferromanganese

Seamount

10.3390/min9070439

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Citations (45)

Submarine Active Faults and Morpho-Tectonics Around the Iberian Margins: Seismic and Tsunamis Hazards

Frontiers in Earth Science (2021)

Luı́s Somoza Teresa Medialdea Pedro Terrinha Adrià Ramos J.T. Vázquez

The aim of this work is to make a synthesis at regional scale focused on the geophysical characterization of submarine faults around the Iberian margin to identify active structures and analyze their development in the framework of the present plate organization. Most of these submarine faults show seabed morphological expressions mapped with high-resolution swath bathymetry data, high-resolution parametric sub-bottom profiles and multichannel seismic profiles. Present active tectonics, deformation, seismicity, and tsunami-affected coastal areas is mainly focused on south Iberia at the Eurasian and Nubia plate boundary. Submarine active faults in these areas are represented by long strike-slip fault systems and arcuate fold-thrust systems. Their development takes place in response to present NW-SE convergence between the Eurasian and Nubia plates. We propose a strain partitioning model of the plate boundary into simple and pure shear zones to explain the distribution and mechanisms of active submarine faults along the Gulf of Cádiz, Gibraltar Arc and Alborán Sea in response to the present-day shear stress orientation. Nevertheless, deformation is also focused in the NW Iberian margin. Thus, along the Galician and Portuguese margin, several submarine faults mapped as thrust fault systems with high-seismic activity along the Iberian ocean-continent transition reflect the re-activation of former structures. We suggest that submarine active faults in the NW and W Iberia are also the response to the eastwards transfer of short-offset transform faults of the Mid Atlantic Ridge into the oceanic Iberian along a weakness as the former plate boundary between the oceanic Iberia and Eurasia domains. The distribution and activity of submarine faults mapped in this work from geophysical and bathymetric data are in good agreement with geodetic data and focal mechanisms.

Passive margin

Transform fault

Convergent boundary

Thrust fault

Continental Margin

Submarine landslide

10.3389/feart.2021.653639

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Citations (35)

High-resolution multibeam bathymetry of the northern Mid-Atlantic Ridge at 45–46° N: the Moytirra hydrothermal field

Journal of Maps (2021)

Luı́s Somoza Teresa Medialdea Javier González Sara Machancoses Jose A. Candón

This work presents a new high-resolution multibeam bathymetric map of a segment of active deep sea-floor spreading in the Atlantic Ocean, the northern Mid-Atlantic Ridge (MAR) at 45–46º N. New high-resolution bathymetry data were acquired using an Atlas multibeam echosounder onboard the research vessel Sarmiento de Gamboa during the EXPLOSEA-2 survey in 2019. The final map of the MAR (50 m cell grid size) at the original scale of 1:200,000 shows a segment of 140 × 35 km of the MAR, at water depths from 715 to 3700 m. This new high-resolution bathymetric map allows to better defining the submarine morphology of the Moytirra hydrothermal active field, the only high-temperature field identified between the Azores Archipelago (Portugal) and Iceland. ROV submarine observations reaching the deepest part of the system for the first time show giant anhydrite-sulfide chimneys up to 20 m high, active strong black smokers and polymetallic massive sulfides.

Echo sounding

Seabed

Mid-Atlantic Ridge

Archipelago

Bathymetric chart

10.1080/17445647.2021.1898485

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Citations (18)

Submarine active tectonics in the south and northwest Iberian margins 

Adrià Ramos Luı́s Somoza Teresa Medialdea Pedro Terrinha J.T. Vázquez

The Iberian Peninsula is surrounded to the north by the convergence margin between Eurasia and the former Iberian plates (North and Northwest Iberian margin), and to the south by a transform plate boundary between Eurasia and Nubia (Gulf of C&#225;diz) to a shear-compressive indentation of Nubia northwards in the Albor&#225;n Sea. These margins are affected by historic and present-day seismicity, which are linked to active tectonic structures deforming the seafloor of the margins. The main objective is to better understand their development in the framework of the present plate organization and thus evaluate the seismic hazard around Iberia. Therefore, we carried out an extensive geophysical characterization of submarine faults, focusing on those that show seabed morphological expressions, by mapping them with high-resolution swath bathymetry data, high-resolution parametric sub-bottom profiles and multichannel 2D seismic profiles. Their activity and distribution are in good agreement with the geodetic and seismological observations.Our results show that the present-day active tectonics and its related deformation, including seismicity and tsunami-affected coastal areas, are mainly located in the south Iberian margin, around the boundary between the Eurasian and Nubia tectonic plates. The submarine active faults are represented in this margin by a large strike-slip fault system and fold-thrust systems, in response to the NW-SE convergence between the aforementioned tectonic plates. The different orientation and distribution of submarine faults, and the fault type from focal mechanism of seismic events, led us to identify simple and pure shear zones from the Albor&#225;n Sea to the east, to the Gibraltar Arc and Gulf of Cadiz to the west. This suggests a strain partitioning model along the plate boundary in response to the present-day shear stress orientation.Deformation is also documented in the NW Iberian margin. Thrust fault systems with high seismic activity were identified and mapped along Iberian ocean-continent transition around the Galician and Portuguese margins, reflecting the re-activation of former Cenozoic faults. Deformation in this margin is also derived from the westward motion of the Iberian oceanic domain and the clockwise rotation of the Iberian continental domain with respect to the Eurasian plate.

Seafloor Spreading

10.5194/egusphere-egu22-11506

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Giant depressions on Atlantic continental margins: Relationship with diapirs

J.T. Vázquez Gemma Ercilla Luı́s Somoza Desirée Palomino Belén Alonso

IX Simposio sobre a Margem Iberica Atlântica (MIA 2018) - IX Simposio sobre el Margen Iberico Atlantico - IX Symposium on the Iberian Atlantic Margin, 4-7 September de 2018, Coimbra.-- 2 pages, 1 figure

Continental Margin

Margin (machine learning)

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Morphological feature analyses of the Prestige half-graben on the SW Galicia Bank

Marine Geology (2007)

Estefanía Llave Marga García C. M. Morcillo Perez M. Sayago M. Farrán

Fault block

10.1016/j.margeo.2007.09.010

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Citations (15)