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An integrated approach combining swath bathymetry, high-resolution seismic reflection and seabed sediment sampling was performed to characterize a field of sand ridges on the Murcia continental shelf in the western Mediterranean Sea. The aim of this work was to improve knowledge about the formation, evolution and presentday dynamics of these bedforms on a narrow, tideless continental shelf receiving little sediment input. Sand ridges are observed on the middle shelf at water depths ranging between 58 and 78 m. The sand ridges are 1.5 to 3 m high and show a predominant E-W orientation oblique to the present-day shoreline. Smaller-scale subaqueous dunes (0.3–1.3 m high) appear superimposed on the sand ridges and beyond the ridge field. The subaqueous dunes show a NW-SE orientation and asymmetric profiles, with the lee side facing southwest. The comparison of two bathymetric surveys 10 years apart revealed that the subaqueous dunes are migrating towards the southwest at very low rates (~3 m yr−1 ). Internally, both sand ridges and dunes display southwestward dipping oblique reflections, indicating long-term migration in that direction. The morphology, architecture and distribution of the Murcia sand ridges suggest that they were formed in a shallow-water environment during the Holocene transgression and were later detached from the coast due to the subsequent sea level rise. The shallow architecture of the sand ridges reveals the presence of small, mound-like features within the sand ridges, most probably associated with coastal deposits, which could have served as a precursor for the development of the sand ridges. The preservation of these deposits within the sand ridges evidences limited offshore ridge migration. At present, active subaqueous dunes superimposed on the sand ridges suggest that they may play a significant role in the ridge evolution. At a regional scale, the comparison of the Murcia sand ridges with those described in the western Mediterranean allows

The magma‐poor rifted continental margin of Galicia has an extremely complex structure. Its formation involved several rifting episodes that occurred ultimately during the early Cretaceous near a ridge triple junction, which produced a change in the orientation of the main structures in its transition to the north Iberia margin. In addition, there is a superimposed partial tectonic inversion along its northwest and northern border which developed from the Late Cretaceous to at least Oligocene times. The present study integrates a large volume of new geophysical information (mainly marine gravity data and 2‐D seismic reflection profiles) to provide insights on the formation of this rift system and on the development of its later inversion. The combined interpretation and modeling of this data enable the presentation of a new crustal and structural domain map for the whole Galicia margin. This includes the rift domains related to the extreme thinning of the crust and the lithospheric mantle (stretched, necking, and hyperextension and mantle exhumation domains), as well as a domain of intense compressional deformation. New constraints arise on the origin, the deep structure, and the characterization of the along‐ and across‐strike variation of the continent‐ocean transition of the margin, where a progressive change from hyperextension to partial inversion is observed. The development of both rifting and later partial tectonic inversion is influenced by the existence of former first‐order tectonic features. Most of the tectonic inversion is focused on the hyperextension and mantle exhumation domain, which in some areas of the northwestern margin is completely overprinted by compressional deformation

Recently acquired swath bathymetry, high-resolution seismic profiles and bottom sediment samples have revealed the presence of large-scale fine-grained sediment waves over the Gulf of Valencia continental slope. Like many other deep-water sediment waves, these features were previously attributed to gravitational slope failure related to creep-like deformation, and have now been reinterpreted as sediment wave fields extending from 250 m depth to the continental rise at ~850 m depth. Sediment wave lengths range between 500 and 1000 m and maximum wave heights of up to 50 m are found on the upper slope, decreasing downslope to a minimum height of 2 m. Seismic profiles showed continuous internal reflectors and several sediment wave packages were differentiated, being thicker on the crest of each wave and thinner on the downslope flank, indicating that these sediment waves are upslope-migrating. The sediment wave formation process was inferred from contemporary hydrodynamic observations, and internal wave activity is suggested to be the most probable mechanism for the sediment transport and deposition and subsequent maintenance of the sediment waves over the Gulf of Valencia continental slope

A sand ridge field with crests oriented NE–SW (52°) located between 55 and 85 m water depth on the Valencia continental shelf (Spain) was mapped with multibeam swath bathymetry and characterized with high-resolution seismic reflection profiling and sediment sampling. Boundary layer hydrodynamic and suspended sediment concentration measurements conducted over a sand ridge at 66 m depth showed evidence of wave and current sediment resuspension during a major storm event. It is argued that these sand ridges developed in a shallow environment and there is no evidence of present-day ridge migration or morphological degradation

Multibeam swath bathymetry, high-resolution seismic data and sediment samples were used to characterize a field of sand ridges and subaqueous dunes on the outer Murcia continental shelf (western Mediterranean Sea). Sand ridges are 1.5–3 m high and show a predominant E-W orientation oblique to the present-day shoreline. High-resolution seismic data reveal a backstepping stacking pattern of high-angle clinoforms dipping towards the southwest, interpreted as buried sand bodies. Subaqueous dunes have a mean height of 0.3 m and appear superimposed on the sand ridges showing a NW-SE orientation oblique to the ridges. They are composed of sandy sediments and display asymmetric morphology, with the lee side towards the southwest. Ridge and dune asymmetry and internal structure are indicative of long-term sediment transport towards the southwest. At present, dune migration rates deduced from repeated bathymetric surveys indicate that the dunes remain stationary or migrate at very low rates on a decadal scale Dune migration rates were determined from the net displacement of the crests and troughs positions deduced from repeated multibeam surveys (2003 and 2013). Results indicate that the subaqueous dunes remain stationary or migrate at low rates towards the southwest (migration rates < 1 m yr-1). Bedform asymmetry and migration are consistent with the general circulation of the margin, characterized by a predominant geostrophic current flowing south-westward along the shelf break

This atlas illustrates the characteristics of present-day bedforms, from the shoreline to deep-sea environments, and it also includes short reviews of the main mechanisms that generate such bedforms. The atlas is aimed at the research community, in addition to students, the public at large and companies with interests in the marine environment. The book is divided into seven sections composed of a number of short chapters: 1) bedform analysis and the main physical processes, 2) bedforms in the coastal zone, 3) bedforms on prodeltas and sorted bedforms, 4) bedforms on the continental shelf, 5) bedforms and benthos, 6) bedforms in submarine canyons and 7) slope and deep-sea bedforms. This atlas offers a comprehensive, though not exhaustive, view of the diversity of bedforms and associated processes and of the morphological and temporal scales in the enclosed tideless western Mediterranean Sea

Multibeam bathymetric data collected along the Menorca Channel (Balearic Islands) for a depth range of 70–850 m revealed the occurrence of bedforms along some of the submarine canyons of the Balearic southern slope. The four main canyons presented in this study display a linear to sinuous geometry, incising the slope for up to 170 m and carving the shelf-edge at a depth of 110 m. Bedforms along these canyons are more developed along the two northernmost canyons, particularly within the 300–700 m depth range. The crescentic shape of the bedforms and their wavelengths of between 120 and 210 m resemble the morphology of bedforms found in other submarine channels and canyons. In line with these previously observed bedforms, we here explore the possibility that the bedforms in the canyons could be interpreted as cyclic steps formed by supercritical turbidity currents. Assuming this interpretation holds, then some simple modelling would allow us to give rough estimates of velocity and thickness of the flows that formed the cyclic steps

La presente Tesis Doctoral lleva por t tulo Geodin amica del margen continental de Galicia: Estructura profunda y morfotect onica. Este estudio se aborda a partir de la integraci on de un gran volumen de nuevos datos geof sicos (gravim etricos, batim etricos y s smica de re exi on multicanal 2D y de ultra-alta resoluci on), procedentes de los proyectos ZEEE, ERGAP y BURATO4242. La nueva informaci on ha aportado constricciones muy relevantes sobre el origen, la estructura profunda y la complejidad siogr a ca del margen, as como sobre la caracterizaci on de la variaci on lateral de la transici on oc eano-continente. El margen continental de Galicia se clasi ca como un margen de rift pobre en magma. Este tipo de m argenes tienen dos rasgos comunes, que son: 1) Los pares de m argenes conjugados son asim etricos, teniendo uno de ellos una zona m as ancha de corteza extremadamente adelgazada, subrayada por un re ector s smico subhorizontal; 2) Entre la corteza continental adelgazada y la corteza oce anica normal, hay una zona de basamento compuesto por manto serpentinizado. La estructura del margen continental gallego es extremadamente compleja, re ejando la superposici on de varias etapas sucesivas de rift, y una etapa compresiva posterior que da como resultado la inversi on parcial del margen. Adem as, la proximidad de un punto triple de dorsal produce un cambio de orientaci on de las estructuras principales. Este margen continental ha sido ampliamente estudiado desde la d ecada de los '70. Sin embargo, la mayor parte de los estudios se han centrado en la parte occidental, existiendo una importante carencia de informaci on en los ancos norte y noroeste. Este hecho, junto con su gran complejidad estructural, ha provocado que no exista un modelo geodin amico previo que integre todos los procesos observados. Algunos aspectos, como son la transici on entre el margen oeste (extensivo) y el margen norte (compresivo), y la forma en que se produce su inversi on tect onica, apen, This PhD Thesis is entitled Geodynamics of the continental margin of Galicia: Deep structure and morphotectonics. This study is approached from the integration of a large volume of new geophysical data (gravimetric, bathymetric, 2D multichannel seismic re ection and ultra-high resolution seismic imaging), from the ZEEE, ERGAP and BURATO4242 projects. The new information has brought signi cant constraints on the origin, the deep structure and the physiographic complexity of the margin, as well as on the characterization of the lateral variation of the oceancontinent transition. The Galicia continental margin is classi ed as a magma-poor rift margin. Margins of this type have two common features, namely: 1) The conjugate margin pairs are asymmetric, one of them showing a wider zone of extreme crustal thinning, as underlined by sub-horizontal seismic re ections; (2) Between the thinned continental crust and the normal oceanic crust, there is an area whose basement is composed of serpentinized mantle. The structure of the Galicia continental margin is extremely complex, since its formation involves several rifting episodes, and a later partial tectonic inversion. In addition, the vicinity of a ridge triple junction produces a change in the orientation of the main structures. This continental margin has been widely studied since the 70's. However, most studies have focused on the western part, and there is a signi cant lack of information on the north and northwestern anks. This fact, along with its great structural complexity, has resulted in the absence of a previous geodynamic model integrating all the processes observed. Some aspects, such as the transition between the western margin (extensive) and the northern margin (compressive), and the way the tectonic inversion develops, have barely been addressed previously by the scientific community...

The Galicia continental margin is a magma-poor rifted margin with an extremely complex structure. Its formation involves several rifting episodes during the Mesozoic in the vicinity of a ridge triple junction, which produces a change in the orientation of the main structures. In addition, there is an overimposed Cenozoic partial tectonic inversion along its northern border. Although this continental margin has been widely studied since the 70’s, most studies have focused on its western part in the transition to the Iberia Abyssal Plain, and there is a significant lack of information on the north and northwestern flanks of this margin. This fact, along with its great structural complexity, has resulted in the absence of a previous comprehensive regional geodynamic model integrating all the processes observed. In the present study we integrate a large volume of new geophysical data (gravity, swath bathymetry and 2D multichannel reflection seismic). Data come from the systematic mapping of the Spanish EEZ project which provides a dense grid of gravity data and full seafloor coverage with swath bathymetry, and from the ERGAP project which provides serially-arranged 2D seismic reflection profiles across the NW Iberia margin. The combined interpretation and modelling of this new information has arisen significant constraints on the origin, the deep crustal structure and the physiographic complexity of the margin, as well as on the characterization of the along- and across-strike variation of the ocean-continent transition along NW Iberia margin. The analysis of this information leads us to propose a conceptual model for the initiation of the tectonic inversion of a magma-poor rifted margin. Finally, a framework for the geodynamic evolution of the Galicia margin has been constructed, involving three main stages: A) an early stage from the end of rifting and oceanic drift in the Bay of Biscay (Santonian); B) an intermediate stage with the beginning of tectonic inversion in

Concepcion Bank is the largest seamount in the Canary Islands Seamount Province (CISP), an oceanic area off NW Africa including 16 main seamounts, the Canaries archipelago and the Selvagens subarchipelago. The Bank is located 90 km northeast of Lanzarote Island and has been identified as a candidate Marine Protected Area (MPA) to be included in the Natura 2000 network. A compilation of complementary datasets consisting of multibeam bathymetry, TOPAS seismic reflection profiles, side scan sonar sonographs, Remotely Operated Vehicle video records and seafloor samples allowed describing in detail and ground truthing the submarine landforms and bioconstructions exhibited by the bank. The Concepcion Bank presently rises up to 2,433 m above the adjacent seafloor and exhibits two main domains: an extensive summit plateau and steep flanks. The sub-round summit plateau is 50km by 45 km and ranges from 158 to 1,485 m depth. The steep flanks that bound it descend to depths ranging between 1,700 and 2,500 m and define a seamount base that is 66km by 53 km. This morphology is the result of constructive and erosive processes involving different time scales, volumes of material and rates of change. The volcanic emplacement phase probably lasted 25–30 million years and was likely responsible for most of the 2,730 km3 of material that presently form the seamount. Subsequently, marine abrasion and, possibly, subaerial erosion modulated by global sea level oscillations, levelled the formerly emerging seamount summit plateau, in particular its shallower (<400 m), flatter (<0.5°) eastern half. Subsidence associated to the crustal cooling that followed the emplacement phase further contributed the current depth range of the seamount. The deeper and steeper (2.3°) western half of Concepcion Bank may result from tectonic tilting normal to a NNE-SSW fracture line. This fracture may still be expressed on the seafloor surface at some scarps detected on the seamount’s summit. Sediment waves an

[EN] The continental margin of Galicia presents a very complex structure, due to two main effects. On the one hand, it's a magma-poor rift margin, generated in the vicinity of the triple R-R-R junction, which resulted in the simultaneous opening of the Atlantic Ocean and the Bay of Biscay during the Cretaceous. On the other hand, the Cenozoic compressive stress regime led to the partial inversion of the continental margin to the north and northwest, providing a greater structural complexity. In this work we have carried out a detailed analysis of new gravity and bathymety data acquired during the ZEE Project cruises, as well as new 2D multichannel seismic reflection profiles from the ERGAP Project. We present here some the results of this joint analysis of all the geophysical and geological information available, consisting of a continuous mapping of the different lithospheric domains and of the style of deformation which affect them, from the western margin of the Iberian Peninsula to the northern one, [ES] El margen continental de Galicia presenta una estructura muy compleja, debido a dos efectos principales. Por un lado, se trata de un margen de rift pobre en magma, generado en las proximidades del punto triple R-R-R que dio lugar a la apertura simultánea del Océano Atlántico y el golfo de Vizcaya durante el Cretácico. Por otra parte, el régimen de esfuerzos compresivo Cenozoico generó la inversión parcial del margen continental hacia el norte y el noroeste, aportando una mayor complejidad estructural. En este trabajo hemos realizado un análisis detallado de la nueva información gravimétrica y batimétrica obtenida durante las campañas del Proyecto ZEE, así como de nuevos perfiles de sísmica de reflexión multicanal procedentes del Proyecto ERGAP. Presentamos aquí parte de los resultados de este análisis conjunto de toda la información geofísica y geológica disponible, consistentes en una cartografía continua de los diferentes dominios litosféricos y del tipo dedeformación que los afectan, desde el margen oeste de la Península Ibérica hasta el margen norte

The Palomares continental margin is located in the southeastern part of Spain. The margin main structure was formed during Miocene times, and it is currently part of the wide deformation zone characterizing the region between the Iberian and African plates, where no well-defined plate boundary occurs. The convergence between these two plates is here accommodated by several structures, including the left lateral strike–slip Palomares Fault. The region is characterized by sparse, low to moderate magnitude (Mw < 5.2) shallow instrumental earthquakes, although large historical events have also occurred. To understand the recent tectonic history of the margin we analyze new high-resolution multibeam bathymetry data and re-processed three multichannel seismic reflection profiles crossing the main structures. The analysis of seafloor morphology and associated subsurface structure provides new insights of the active tectonic features of the area. In contrast to other segments of the southeastern Iberian margin, the Palomares margin contains numerous large and comparatively closely spaced canyons with heads that reach near the coast. The margin relief is also characterized by the presence of three prominent igneous submarine ridges that include the Aguilas, Abubacer and Maimonides highs. Erosive processes evidenced by a number of scars, slope failures, gullies and canyon incisions shape the present-day relief of the Palomares margin. Seismic images reveal the deep structure distinguishing between Miocene structures related to the formation of the margin and currently active features, some of which may reactivate inherited structures. The structure of the margin started with an extensional phase accompanied by volcanic accretion during the Serravallian, followed by a compressional pulse that started during the Latemost Tortonian. Nowadays, tectonic activity offshore is subdued and limited to few, minor faults, in comparison with the activity recorded onshore. The deep Algero

Detailed analysis of recently acquired swath bathymetry, together with high-resolution seismic profiles and bottom sediment samples, revealed the presence of large-scale fine-grained sediment waves over the Gulf of Valencia continental slope. As many other deep-water sediment waves, these features were previously attributed to gravitational slope failure, related to creep-like deformation, and are here reinterpreted as sediment wave fields extending from 250m depth to the continental rise, at ~850m depth. Geometric parameters were computed from the high-resolution multibeam dataset. Sediment wave lengths range between 500 and 1000m, and maximum wave heights of up to 50m are found on the upper slope, decreasing downslope to minimum values of 2m high. Sediment waves on the lower part of the slope are quasi-stationary vertically accreting, whereas they show an upslope migrating pattern from the mid-slope to the upper part of the continental slope. High-resolution seismic profiles show continuous internal reflectors, with sediment waves merging down-section and sediment wave packages decreasing in thickness downslope. These sediment packages are thicker on the crest of each individual sediment wave and thinner on the downslope flank. 210Pb analyses conducted on sediment cores collected over the sediment wave fields also indicate slightly higher sediment accumulation rates on the wave crests. Sediment wave formation processes have been inferred from contemporary hydrodynamic observations, which reveal the presence of near-inertial internal waves interacting with the Gulf of Valencia continental slope. Internal wave activity is suggested to be the preferential mechanism for the transport and deposition of sediment, and the maintenance of the observed sediment wave fields. © 2015 Elsevier B.V.

La presente Tesis Doctoral lleva por t tulo Geodin amica del margen continental de Galicia: Estructura profunda y morfotect onica. Este estudio se aborda a partir de la integraci on de un gran volumen de nuevos datos geof sicos (gravim etricos, batim etricos y s smica de re exi on multicanal 2D y de ultra-alta resoluci on), procedentes de los proyectos ZEEE, ERGAP y BURATO4242. La nueva informaci on ha aportado constricciones muy relevantes sobre el origen, la estructura profunda y la complejidad siogr a ca del margen, as como sobre la caracterizaci on de la variaci on lateral de la transici on oc eano-continente. El margen continental de Galicia se clasi ca como un margen de rift pobre en magma. Este tipo de m argenes tienen dos rasgos comunes, que son: 1) Los pares de m argenes conjugados son asim etricos, teniendo uno de ellos una zona m as ancha de corteza extremadamente adelgazada, subrayada por un re ector s smico subhorizontal; 2) Entre la corteza continental adelgazada y la corteza oce anica normal, hay una zona de basamento compuesto por manto serpentinizado. La estructura del margen continental gallego es extremadamente compleja, re ejando la superposici on de varias etapas sucesivas de rift, y una etapa compresiva posterior que da como resultado la inversi on parcial del margen. Adem as, la proximidad de un punto triple de dorsal produce un cambio de orientaci on de las estructuras principales. Este margen continental ha sido ampliamente estudiado desde la d ecada de los '70. Sin embargo, la mayor parte de los estudios se han centrado en la parte occidental, existiendo una importante carencia de informaci on en los ancos norte y noroeste. Este hecho, junto con su gran complejidad estructural, ha provocado que no exista un modelo geodin amico previo que integre todos los procesos observados. Algunos aspectos, como son la transici on entre el margen oeste (extensivo) y el margen norte (compresivo), y la forma en que se produce su inversi on tect onica, apen

A sand ridge field with crests oriented NE-SW (52°) located between 55 and 85m water depth on the Valencia continental shelf (Spain) was mapped with multibeam swath bathymetry and characterized with seismic profiling and sediment sampling. Boundary-layer hydrodynamic measurements conducted over a sand ridge at 66m depth show evidence of wave and current sediment resuspension during a major storm event with a three-year recurrence period. From the measured intrawave sediment concentration profiles it is shown that the suspended sediment time evolution is related not only to mean currents but also to the wave field. The near-bottom shear stress generated during storm conditions reached around 1N/m2 and was able to resuspend and transport sandy and muddy sediments for more than 32h. The total suspended sediment transport in a layer of 1m above the bottom was around 4000kg per meter width and directed 160°.It is argued that these sand ridges were developed in a shallow environment and there is no evidence of present-day ridge migration or morphological degradation. It is hypothesized that sediment dynamics affecting sand ridges during storms favors the maintenance of their morphology. © 2015 Elsevier B.V.

El banco de Galicia es un monte submarino profundo situado a 180 km de la costa gallega, con una cima situada entre los 650 y los 1.500 m de profundidad y rodeado de zonas abisales de más de 4.000 m de profundidad. El relieve de las montañas submarinas interactúa con la circulación oceánica modificando las condiciones de oligotrofismo imperantes en el mar profundo. El cambio de dirección de las corrientes marinas, al chocar con el banco, produce las llamadas columnas de Taylor que tienen como consecuencia giros sobre la cima y finalmente un enriquecimiento de las aguas que bañan el banco, lo que influye, a través de la cadena trófica, en las especies de cetáceos, aves y tortugas. Estas condiciones, junto al aislamiento de estos bancos, convierten a estos bancos en puntos calientes de biodiversidad. Esta teoría se ha visto corroborada por los estudios realizados en el proyecto INDEMARES, basados en dos campañas de investigación, dónde se ha encontrado una elevada biodiversidad y la presencia de hábitats vulnerables. El banco de Galicia está bañado por tres capas diferentes: la masa de agua central del Atlántico nordeste europeo (East North Atlantic Central Water: ENACW), por debajo de las aguas superficiales y hasta los 500-600 m; la masa de agua mediterránea (Mediterranean Outflow Water: MOW) y la masa de agua del Labrador (Labrador Sea Water: LSW), que es la capa más profunda. En cuanto al tipo de fondo, se encuentra roca en el área del flanco oriental y hacia el sureste y en los montes adyacentes como el Rucabado, distinguiendo claramente dos tipos en cuanto a la pendiente, correspondiendo con la roca plana de la cima y la roca en pendiente del borde del banco y paredes. En la cima se encuentran fondos de arenas medias, de reflectividad media y baja según el espesor de sedimento, y arenas finas en los fondos sedimentaruios de los flancos, a profundidades mayores de 1.500. En el banco se han identificado hasta el momento 793 especies, con taxones que superan las 10

Esta campaña ha consistido en una prospección por métodos Geofísicos de los fondos que albergarán en un futuro la Infraestructura Científico Técnica Singular (ICTS) PLOCAN; Plataforma Oceánica de Canarias. Los trabajos se han llevado a cabo a bordo del B/O Ángeles Alvariño, y en ellos han participado, junto al IEO, el IHM Instituto Hidrográfico de la Marina, y la UB Universidad de Barcelona. Las tres instituciones han puesto en común el personal participante que ha desarrollado además de la tarea conjunta y compartida de la adquisición de los datos, otras tareas del interés particular de cada organismo como la formativa en el caso de la UB, la de obtención de datos brutos y procesado para la edición de cartas náuticas en el caso del IHM, y la de obtención de datos y procesado con fines científicos desarrollada por el personal del IEO

El Mapa Topobatimétrico en relieve del margen continental del principado de Asturias, es un producto destinado a la divulgación científica y a la enseñanza. Ha sido realizado aprovechando el resultado de varios estudios del Instituto Español de Oceanografía (IEO) y la Secretaría General de Pesca (SGP) sobre los fondos marinos y su geología. Se trata, por tanto, de un producto derivado de la actividad científica y tecnológica del IEO y de la SGP. El presente mapa es el quinto de una serie que muestra nuestros fondos marinos, y se enmarca dentro de una campaña de divulgación de las ciencias del mar que ha iniciado el IEO para contribuir a mejorar la cultura científica de la sociedad española y el conocimiento que ésta tiene del Instituto y sus actividades.

Se trata de un libro que pretende divulgar a la sociedad las principales investigaciones multidisciplinares llevadas a cabo por el Instituto Español de Oceanografía durante su primer siglo de vida, y dar a conocer la historia del organismo, de su Sede Central y de los nueve centros oceanográficos repartidos por los litorales mediterráneo y atlántico, en la península y archipiélagos.

The Avilés Canyon System (ACS) is a complex, structurally-controlled canyon and valley system constituted by three main canyons of different morphostructural character. They are, from east to west: La Gaviera Canyon, El Corbiro Canyon and Avilés Canyon. In addition to this ACS, a new canyon has been surveyed: Navia Canyon. We present for the first time a high resolution multibeam map showing with great detail the morphological and structural complexity of this segment of the Cantabrian margin. ACS presents a tectonic imprint marked by NW-SE, NNE-SSW and E-W structures. The morphology of their reaches as well as their single mouth, in addition to some rock dredges in their major valleys, demonstrates active down-slope flushing. The continental shelf shows a flat, uniform slope with local and well defined rock outcrops south of Aviles Canyon head. Sedimentary zones are limited, showing thin unconsolidated sedimentary cover. Strong continental margin water dynamics avoid thicker sediment deposition, being littoral sedimentary dynamics responsible for transport to the canyons heads and conduit to the Biscay Abyssal plain. Biscay Abyssal Plain shows evidence of a strong westward current affecting the surveyed strip of this more than 10 km wide plain. Presence of two parallel deep sea channels, erosive scarps, and erosion of gully divides on the lower slope, may indicate that this is part of the distal fan at the termination of the large turbiditic system fed by Cap Ferret, Capbreton and other large canyons (Santander, Torrelavega, Lastres and Llanes) to the west of ACS.

El proyecto INDEMARES ha permitido utilizar amplios medios económicos y personales para estudiar en detalle y desde múltiples perspectivas la zona del Sur de Fuerteventura (montes de Amanay y El Banquete). Se han aplicado metodologías para el estudio de la hidrografía, caracterizando la región, describiendo sus principales masas de agua y la hidrodinámica de las corrientes. También se ha abordado la geología de la zona, incluyendo levantamientos batimétricos, perfiles sísmicos, muestreos de sedimento y petrológicos, obteniendo modelos digitales del terreno, mapas de tipos de fondo, geomorfológicos. Se han caracterizado las comunidades bentopelágicas, demersales, epibentónicas y endobentónicas, prestando especial atención a aquellas que conforman o estructuran los hábitats sensibles cuyo inventariado y cartografía era objeto principal del proyecto. Los trabajos de identificación de hábitats se han realizado con muestreadores directos, pero también con muestreadores visuales, que han permitido hacer un mayor esfuerzo de muestreo sin aumentar el impacto sobre los fondos de la zona. Por otro lado se ha estudiado la huella pesquera de la zona por medio del análisis de los datos VMS y los cuadernos de pesca proporcionados por la SGP, además de una ardua labor a pie de puerto de entrevistas y encuestas. Toda la información ha sido gestionada y analizada por diferentes grupos de investigación de diferentes centros (Universidad de La Laguna, Instituto Universitario de Ciencias Políticas y Sociales, Universidad de Las Palmas de Gran Canaria, Instituto de Ciencias del Mar de Barcelona, Universidad de Barcelona, Centro de Investigaciones Medioambientales del Atlántico, Centro Oceanográfico de Santander y Centro Oceanográfico de Málaga del Instituto Español de Oceanografía, …), aunque el grueso de esta labor, además de la coordinación, se ha llevado a cabo en el Centro Oceanográfico de Canarias del Instituto Español de Oceanografía. Los resultados permiten tener un conocimiento, INDEMARES Project made possible to bring together economic and staff resources to study in detail, and from multiple perspectives, the area of South of Fuerteventura (Amanay and El Banquete Semounts). Methodologies have been applied to study hydrography, making a regional characterization, depicting main water masses, and current hydrodynamics. Geology has been tackled including bathymetric uplifting, seismic profiles, sediment and petrological sampling, obtaining digital terrain models, type of bottom maps, geomorphological maps, as an output. Benthopelagic, demersal, epibenthic and endobenthic communities have been characterized, paying special attention to sensitive habitats which inventory and mapping was the project’s main aim. Habitat identification has been made with direct and visual samplers, the latter making a major sampling effort possible without an increase of bottom impact. Moreover, fisheries footprint has been identified by Vessel Monitoring System data, together with logbooks from Secretaría General de Pesca (Fisheries Ministry), as well as a hard interviewing and surveying task at landing points. Information has been managed and analysed by different research groups from different Centres (Universidad de La Laguna, Instituto Universitario de Ciencias Políticas y Sociales, Universidad de Las Palmas de Gran Canaria, Instituto de Ciencias del Mar de Barcelona, Universidad de Barcelona, Centro de Investigaciones Medioambientales del Atlántico, Centro Oceanográfico de Santander y Centro Oceanográfico de Málaga del Instituto Español de Oceanografía), although the main body of the work, plus coordination, has been made by the Canary Islands Oceanographic Centre, from the Spanish Institute of Oceanography. Results let us have a multidisciplinary profound knowledge of the study zone, comparable to few other marine research projects off Macaronesia. The study about oceanography, geology and biologic communities has allowed the habitats characteriz

El proyecto INDEMARES ha permitido utilizar amplios medios económicos y personales para estudiar en detalle y desde múltiples perspectivas la zona del Banco de La Concepción. Se han aplicado metodologías para el estudio de la hidrografía, caracterizando la región, describiendo sus principales masas de agua y la hidrodinámica de las corrientes. También se ha abordado la geología de la zona, incluyendo levantamientos batimétricos, perfiles sísmicos, muestreos de sedimento y petrológicos, obteniendo modelos digitales del terreno, mapas de tipos de fondo, geomorfológicos. Se han caracterizado las comunidades bentopelágicas, demersales, epibentónicas y endobentónicas, prestando especial atención a aquellas que conforman o estructuran los hábitats sensibles cuyo inventariado y cartografía era objeto principal del proyecto. Los trabajos de identificación de hábitats se han realizado con muestreadores directos, pero también con muestreadores visuales, que han permitido hacer un mayor esfuerzo de muestreo sin aumentar el impacto sobre los fondos de la zona. Por otro lado se ha estudiado la huella pesquera de la zona por medio del análisis de los datos VMS y los cuadernos de pesca proporcionados por la SGP, además de una ardua labor a pie de puerto de entrevistas y encuestas. Toda la información ha sido gestionada y analizada por diferentes grupos de investigación de diferentes centros (Universidad de La Laguna, Instituto Universitario de Ciencias Políticas y Sociales, Universidad de Las Palmas de Gran Canaria, Instituto de Ciencias del Mar de Barcelona, Universidad de Barcelona, Centro de Investigaciones Medioambientales del Atlántico, Centro Oceanográfico de Santander y Centro Oceanográfico de Málaga del Instituto Español de Oceanografía, …), aunque el grueso de esta labor, además de la coordinación, se ha llevado a cabo en el Centro Oceanográfico de Canarias del Instituto Español de Oceanografía. Los resultados permiten tener un conocimiento profundo y multidisciplinar de, INDEMARES Project made possible to bring together economic and staff resources to study in detail, and from multiple perspectives, the area of Banco de La Concepción. Methodologies have been applied to study hydrography, making a regional characterization, depicting main water masses, and current hydrodynamics. Geology has been tackled including bathymetric uplifting, seismic profiles, sediment and petrological sampling, obtaining digital terrain models, type of bottom maps, geomorphological maps, as an output. Benthopelagic, demersal, epibenthic and endobenthic communities have been characterized, paying special attention to sensitive habitats which inventory and mapping was the project’s main aim. Habitat identification has been made with direct and visual samplers, the latter making a major sampling effort possible without an increase of bottom impact. Moreover, fisheries footprint has been identified by Vessel Monitoring System data, together with logbooks from Secretaría General de Pesca (Fisheries Ministry), as well as a hard interviewing and surveying task at landing points. Information has been managed and analysed by different research groups from different Centres (Universidad de La Laguna, Instituto Universitario de Ciencias Políticas y Sociales, Universidad de Las Palmas de Gran Canaria, Instituto de Ciencias del Mar de Barcelona, Universidad de Barcelona, Centro de Investigaciones Medioambientales del Atlántico, Centro Oceanográfico de Santander y Centro Oceanográfico de Málaga del Instituto Español de Oceanografía), although the main body of the work, plus coordination, has been made by the Canary Islands Oceanographic Centre, from the Spanish Institute of Oceanography. Results let us have a multidisciplinary profound knowledge of the study zone, comparable to few other marine research projects off Macaronesia. The study about oceanography, geology and biologic communities has allowed the habitats characterization and mapping by means of intensive samp

During the last years, the increasing application of multibeam sonar systems for mapping the seafloor has revealed the occurrence of sedimentary bedforms on the continental shelves worldwide. In addition, repeated multibeam surveys are used to monitor and compare the temporal evolution of such morphologies providing important insights into the sedimentary processes on the continental shelf. In the Murcia continental shelf, Western Mediterranean Sea, a large filed of subaqueous dunes has been observed in the middle and outer shelf. Here, we present a detailed morphologic and sedimentological analysis of these features with the aim to discuss their possible mechanism of formation and assess their potential mobility. The findings are based on swath-bathymetry collected using a SIMRAD EM 710 and EM3000D multibeam echosounders, high-resolution seismic profiles acquired with a TOPAS 018 system and sediment samples. Dunes are widely distributed between 60 and 110 m depth, from the Cope Cape, to the north, to the Águilas submarine canyon head rim, to the south. Dunes range from 18 to 140 m in wavelength and from 0.29 to 1.28 m in height. Dunes have asymmetrical profiles (average asymmetry of 0.065) with the lee slope facing towards the southwest that indicate a net south-westward sediment transport. Seabed samples collected in the crests and troughs of individual dunes show a similar grain-size distribution curve, but differ in the content of fines, which is higher in the trough, whereas the crests are dominated by coarse particles. High resolution seismic profiles reveal the presence of a continuous strong reflector that constitutes the base of the subaqueous dunes and could likely correspond to the Holocene transgressive ravinement surface. Dune migration rates were determined from the net displacement of the crests and troughs positions deduced from repeated multibeam surveys (2003 and 2013). Results indicate that the subaqueous dunes remain stationary or migrate at low

Recently acquired swath bathymetry on the Gulf of Valencia continental margin (NW Mediterranean Sea) allowed characterizing a large-scale sediment wave field which develops on the continental slope, from 250 m in depth to the continental rise, found at 850 m in depth. Geometric parameters as wavelength, wave height, asymmetry index, and steepness were obtained from the analysis of the bathymetric models. The internal structure of the sediment waves was determined using parametric (TOPAS), single-channel (Sparker) and multi-channel (Airgun) seismic reflection profiles. Sediment wavelengths range between 500 and 1000 m, and maximum wave heights of up to 50 m were observed on the upper-slope, decreasing downslope to just 2 m high on the continental rise. These depositional sediment waves over the continental slope are preferentially developed on the foreset region of the prograding margin clinoform, and are preserved in the sediment record since the Early/Lower Pliocene. Contemporary hydrodynamic data have determined the presence of strong near-inertial internal waves interacting with the continental slope, playing an important role in the redistribution of near-bottom suspended particles. Such hydrodynamic process can contribute to the sediment transport and deposition and to the formation of the sediment waves over the Gulf of Valencia continental slope. These morphological features were previously interpreted as a result of gravitational slope failures. However, the use of adequate seafloor mapping techniques, together with oceanographic and sedimentary dynamics measurements, allowed changing the previous interpretation and providing new insights on the seafloor morphology over this part of the NW Mediterranean continental margin

Recently acquired swath bathymetry and seismic datasets revealed the presence of a series of very-large undulations over the Gulf of Valencia (GoV) continental slope. Such undulations have already been described in previous studies, interpreted as a result of sliding and/or creeping processes, presumably affected by neotectonic fracture system, which apparently produced mass movements along the continental slope. However, the analysis of previous data could have been misinterpreted similar to other case studies, such as the “Humbolt slide” (northern California) or the Landes Plateau slope. In this study we present newly detailed morphological and geometrical analysis of the sediment undulations observed on the GoV continental slope. Morphological parameters and quantitative measurements of the undulations were computed, measuring the common geomorphic parameters from the multibeam dataset (i.e. wave-length, wave-height, asymmetry index, slope, etc.). In addition, seismic profiles were acquired at different resolutions across the undulations using TOPAS, Sparker and Airguns. The interpretation of the internal structure of such undulations indicated that they correspond to depositional sediment waves that affect a large portion of the continental slope sedimentary record, being preferentially developed in the three major fields separated by structural heights. The sediment waves formation processes has been inferred from contemporary hydrodynamics observations, which indicate that near-inertial internal waves interacting with the GoV continental slope could play an important role in redistribution of near-bottom suspended particles, contributing to the development and/or maintenance of such sediment wave fields. This study will provide a new detailed characterization of the sediment waves observed over the GoV, and suggest a formation model that could be extended to similar sediment waves fields developed in continental slope regions elsewhere

Sediment starved passive margins, particularly those of insular slopes, display significant mass transport activity despite the absence of environmental stresses from high sedimentation rates. The “Menorca Channel” represents the up to 120 m deep shelf sector connecting the Menorca and Mallorca Islands (Balearic Islands – Western Mediterranean). South of the Menorca Channel submarine gravitational processes have been mapped and interpreted from swath-bathymetry, TOPAS parametric echosounder and deep-towed videos. The shelf-break is located at an average depth of 140 m, and sediment instability is a widespread phenomenon. The slope region south the Menorca Channel shows a number of submarine canyons disrupting the outer shelf. The north-easternmost canyon is the more active feature, with an incised axis and scars shaping the flanks up to their edges. Headwall scarps, between 140 and 700 m depth, are up to 20 m high. The shallower scarps producing slab-type failures have carved the outer edges of planar sedimentary bodies interpreted as formed in shallow environments during previous glacial stages. Results show that a variety of sediment instability processes extensively shape the southern upper slope of the Menorca Channel. Submarine canyons develop on the Emile Bodout Escarpment (EBE), a passive tectonic feature which bounds the slope region of the study area. A number of knickpoints within the canyons suggest backward erosion control on mass wasting and, at the same time, that slope failure is one of the main drivers for canyon upslope migration. Steep gradients of the upper slope, the presence of weak layers and the action of major storms during lowstand stages are additional factors likely to influence the distribution and frequency of mass wasting processes in this area

Surveys conducted at the complex Avilés Canyon System (southern Bay of Biscay) in order to identify vulnerable habitats and biological communities revealed the presence of noteworthy deep-water coral reefs in one of the tributaries of the system (La Gaviera Canyon). The aim of the present study is to determine why this deep-sea canyon provides suitable environmental conditions for corals to grow. This hanging canyon is characterized by an irregular U-shaped floor with two narrow differentiated flanks. Sand ripples and rocky outcrops structured in diverse W–E directed steps are observed on the canyon floor, suggesting intense hydrodynamic activity. Accordingly, high-frequency near-bottom current and thermal structure profiles showed that there occur strong shifts in currents/hydrography behaving as front-like features at each tidal cycle. These involve the sudden increase of along-axis velocities to over 50 cm/s and vertical velocities of over 5 cm/s in each tidal cycle associated with the passage of sharp thermal fronts and thermal inversions suggesting overturning. A year-long near-bottom current record showed events with near-bottom velocities well over 1 m/s lasting for several days. Three cold-water coral settings were distinguished: a dense coral reef located on stepped rocky bottoms of the eastern and western flanks, carbonate mounds (20–30 m high) located on the canyon floor, and a cluster of shallower water dead coral framework at the head sector of the canyon. Video and still images from a towed sled and ROV verified the presence of dropstones and rippled sand sheets surrounding the mounds and revealed changes in the coral population (alive or dead; total or patchy coverage) in coral reef and carbonate mound areas. The dominant species of the reef are Lophelia pertusa and Madrepora oculata, which considerably increase the habitat′s complexity and biodiversity in relation to other facies described in the canyon. The presence of living cold-water reefs is dir