Search

En el margen septentrional del Mar de Alborán, la deformación compresiva relacionada con la convergencia entre las placas de Eurasia y Nubia se resuelve mediante una intensa fracturación según dos grandes sistemas de fallas de dirección NNE-SSO con movimiento sinestro y NO-SE de desplazamiento dextral-normal. El análisis estructural de los elementos geomorfológicos presentes en el fondo marino permite establecer, además, una serie de elementos morfológicos generados por la actividad de pliegues anticlinales y sinclinales que conforman una serie de elevaciones de dirección N050-060ºE. Estos pliegues deforman a las unidades sedimentarias superficiales y han sido activos al menos durante el Cuaternario, como lo demuestra el patrón de espesores de las unidades sísmicas afectadas por el plegamiento y la deformación de la superficie erosiva asociada a una terraza contornítica. Este patrón de estructuras se interpreta como generado por la deformación existente sobre una falla de cabalgamiento, vergente hacia el norte, que asume parte de la deformación compresiva causada por la indentación del bloque de la Dorsal de Alborán. In the northern margin of the Alboran Sea, the compressive deformation related to the convergence between the Nubian and Eurasian plates is resolved by an intense fracturing along two large fault systems trending NNE-SSW with left-lateral movements and NW-SE with right-lateral normal components. The structural analysis of the geomorphological elements on the seafloor also allows us to establish a series of morphological elements generated by the activity of some anticline and syncline fold sets. It is basically a series of ridges heading N050-060ºE. These folds deform the shallow sedimentary units and have been active at least during the Quaternary, as evidenced by the thickness pattern of seismic units affected by the folding and the deformation of an erosive surface associated with a contouritic terrace. This pattern of structures is interpreted to be generated by the overlying deformation on a thrust fault, verging towards the north, which assumes part of the compressive deformation caused by the indentation of the Alborán Ridge block.

El análisis morfotectónico del sector central del Promontorio Balear, entre las islas de Ibiza y Mallorca, mediante batimetría multihaz y perfiles sísmicos de muy alta resolución ha permitido diferenciar varios rasgos morfológicos relacionados con la tectónica a dos escalas. Los elementos de gran escala, de dirección NE-SO, son: i) el escarpe Émile Baudot; ii) el monte submarino Émile Baudot, y iii) la alineación de montes submarinos Ausiàs March y Ses Olives. Los elementos de pequeña escala son: i) dos elevaciones longitudinales (ENE-OSO); ii) escarpes rectilíneos (NO-SE a NE-SO); iii) depresiones tectónicas (NNE SSO a NE-SO); y iv) alineaciones rectilíneas de pockmarks (NO-SE a NNE-SSO). Los elementos de mayor tamaño responden a la configuración estructural neógeno-cuaternaria. El escarpe Émile Baudot limita el Promontorio Balear y la cuenca oceánica del Mediterráneo Occidental. La alineación de montes submarinos Ausiàs March y Ses Olives está generada por una fase extensional, y el monte submarino Émile Baudot forma parte de una alineación volcánica NO-SE asociada a la Zona de Fractura de Ibiza. Los elementos de pequeña escala están relacionados con estructuras tectónicas activas que deforman las unidades sedimentarias del Cuaternario y el fondo marino. Las elevaciones longitudinales están generadas por pliegues anticlinales, mientras que el resto de estructuras están asociadas a la actividad de fallas normales de buzamiento alto. A morphotectonic analysis has been carried out between the islands of Ibiza and Majorca in the central sector of the Balearic Promontory using multibeam bathymetry and very high-resolution seismic profiles. Several morphological features related to tectonics at two different scales have been differentiated. The large-scale features have a NE-SW direction, they are: i) the Émile Baudot Escarpment; ii) the Émile Baudot seamount, and iii) the Ausiàs March and Ses Olives seamounts alignment. The differentiated small-scale elements are i) two longitudinal elevations (ENE-WSW); ii) rectilinear scarps (NW-SE to NE-SW); iii) tectonic depressions limited by one or two scarps (NNE-SSW to NE-SW), and iv) rectilinear pockmarks alignments (NW-SE to NNE-SSW). The largest elements respond to the Neogene-Quaternary structural configuration. The Émile Baudot escarpment is the limit between the Balearic Promontory and the Western Mediterranean oceanic basin. The alignment of the Ausiàs March and Ses Olives seamounts respond to the last extensional phase, and the Émile Baudot seamount forms part of a NW-SE volcanic alignment that could be associated with the Ibiza Fracture Zone. The smaller elements are related to active tectonic structures that deform Quaternary sedimentary units and the seafloor. The longitudinal elevations correspond to anticlinal folds, while the rest of the structures are associated to the activity of near vertical normal faults.

Plasencia, Cáceres, 18-21 de Octubre de 2021., Climate change may determine future trends of animal populations. Specifically, climate limitations may be released or tightened depending on species¿ climatic preferences. Here we assessed the limitation imposed by annual mean temperature and annual precipitation on the maximum potential abundance of 28 common bird species monitored by SACRE Program of SEO/BirdLife throughout 20 years. For each species we developed 20 models, each one corresponding to one year, and assessed their predictive capacity in the remaining 19 years. We found that 98% of models were better than the null model (dAIC

The Western Mediterranean basin has been formed by Miocene back-arc extension and is underlain by a thin and young lithosphere. This young lithosphere is warm, as testified by an overall elevated offshore heat flow. Heat flow within the Western Mediterranean is, however, highly variable and existing data are unevenly distributed and poorly studied in the central part of the Liguro-Provençal and Algero-Balearic basins. This central part is floored by a young oceanic crust, bordered by different continental margins, cut by transform faults, and filled by up to 8 km of sediments. We present a total of 148 new heat flow data collected during the MedSalt and WestMedFlux cruises in 2015 and 2016 and aligned along seven regional profiles that show an important heat flow variability on the basin-scale, but also locally on the margins. A new heat flow map for the Western Mediterranean outlines the following regional features: (1) a higher average heat flow in the Algero-Balearic basin compared to the Liguro-Provençal basin (94 ± 13 mW/m2 and 78 ± 16 mW/m2, respectively), and (2) a regional thermal asymmetry in both basins, but with opposed heat flow trends. Up to 20% of this heat flow difference can be explained by sediment blanketing, but age and heterogeneity of ocean crust due to an asymmetric and polyphased opening of the basins are believed to have given the major thermal imprint. Estimates of the age of the oceanic crust based on the new heat flow suggest a considerably younger West Algerian basin (16–23 Ma) compared to the East Algerian basin and the West Sardinia oceanic floor (31–37 Ma). On the margins and ocean-continent transitions of the Western Mediterranean the new heat flow data point out the existence of two types of local anomalies (length scale 5–30 km): (1) locally increased heat flow up to 153 mW/m2 on the Gulf of Lion margin results from thermal refraction of large salt diapirs, and (2) the co-existing of both low (110 mW/m2) heat flow areas on the South Balearic margin suggests a heat redistribution system. We suspect the lateral heat advection is resulting from a regional fluid circulation in the sediments associated to the widespread Plio-Pleistocene volcanism on the South Balearic margin

The Iberian margin in the Gulf of Cádiz hosts a fluid venting area embedded into a contourite depositional drift and is a natural laboratory to study how multiple interacting processes shape the seafloor. A high-resolution morpho-sedimentary analysis, based on geophysical data, sediment samples and submarine imagery, has been carried out; the onset and evolution of the main geoforms are discussed; and the influence of geological, oceanographic and biogenic processes conditioning substrate types and benthic community distribution are evaluated. The interplay of geological (e.g., salt and shale diapirism, mud volcanism), oceanographic (e.g., water mass circulation, secondary circulation, vertical eddies, internal waves) and biogenic (e.g., methane derived authigenic carbonates formation, coral mound aggradations) processes drive the formation of a large variety of geoforms including, among others, contourite drifts, channels, diapiric ridges, mud volcanoes, pockmarks, and coral mounds. At a smaller scale, the interaction between massive and fluid extrusive, biogenic, and bottom current-related processes (both depositional and erosive) determines the distribution of substrate types and benthic communities, which have been classified as belonging to different biotopes.

It is well known that bottom trawling affects the abiotic (seafloor morphology, sediment resuspension, water turbidity) and biotic components (biodiversity, biomass and production) of habitats. However, comparative studies on the effect of trawling on epibenthic communities of sedimentary bottoms are scarce. One of the objectives of LIFE IP INTEMARES project is to assess the impact of bottom trawling on vulnerable benthic habitats of the circalittoral bottoms of the Menorca Channel (western Mediterranean), designated Site of Community Importance (SCI) within the Natura 2000 network. The present study compares the benthic communities of four areas subjected to different bottom trawl fishing intensity levels (null, intermediate and high). The assignment of fishing effort levels was based on the fishing effort distribution in the area calculated from Vessel Monitoring System (VMS) data. The biological samples were collected from 46 beam trawl stations sampled during a scientific survey on April 2019. In order to detect differences related to the different levels of fishing intensity, we calculated four “traditional” diversity indices (i.e. species richness, Margalef’s richness, Pielou’s evenness and Shannon’s diversity), and the recently developed N90 diversity index, which has shown to be useful in the detection of the response of demersal and benthic communities to fishing pressure. Our results show the highest values of all the analyzed indices in the nonimpacted area, suggesting a negative effect of bottom trawling on the benthic communities present in Menorca Channel. However, no clear pattern was observed between different degrees of trawling intensity and diversity values, so other factors such as environmental conditions must be also considered to explain these results.

Based on geophysical (multibeam echosounder and very high resolution parametric profiles) and sedimentological (Shipek dredge) data acquired during the INTEMARESCANAL0419 expedition, different geomorphologic features have been identified. The study area is located in the continental shelf of the Menorca Channel between 37 and 116 m water depth (mwd). Shallower zones are dominated by lense shaped bedforms, up to 1 m high. They are characterized by very low backscatter values. Also small circular -or slightly elongated- mounds are very frequent morphologies occurring up to 100 mwd. Their sizes range from 1 to 5 m high and 20 to 80 m of diameter with high backscatter values. The most prominent morphological features at intermediate depths are a set of channels that dig in the shelf from 60 to 90 mwd. They show vertical walls and extend up to several km. In the parametric profiles, paleochannels filled by a sedimentary layer approximately 30 ms (two-way time) thick can be observed. The deepest zones are characterized by an erosive surface covered by a thin layer of no consolidated sediments. A visual analysis of the samples shows that sediments are characterized by coarse sand and gravel mainly composed of biogenic particles (carbonated fragmented bioclasts). Higher values of backscatter correspond to samples with a variable abundance of rhodoliths whereas lower values correspond to sands. The variety of morphological features can be mainly related to erosive and depositional Quaternary processes in the continental. Benthic communities strongly influence sediment composition, which was found to be characterized by a high carbonate content.

Tagoro, the youngest submarine volcano of the Canary Islands, erupted in 2011 South of El Hierro Island. Pre-existing sea floor and inhabiting biological communities were buried by the newly erupted material, promoting the appearance of new habitats. The present study pursues to describe the first metazoans colonizing different new habitats formed during the eruption and to create precedent on this field. Through dredge and remote operated vehicle samplings, five main habitat types have been detected based on the substrate type and burial status after the eruption. Inside the Tagoro volcanic complex (TVC), two new habitats are located in and around the summit and main craters—hydrothermal vents with bacterial mats and sulfurous-like fields mainly colonized by small hydrozoan colonies. Two other habitats are located downslope the TVC; new hard substrate and new mixed substrate, holding the highest biodiversity of the TVC, especially at the mixed bottoms with annelids (Chloeia cf. venusta), arthropods (Monodaeus couchii and Alpheus sp.), cnidarians (Sertularella cf. tenella), and molluscs (Neopycnodonte cochlear) as the first colonizers. An impact evaluation was done comparing the communities of those habitats with the complex and well-established community described at the stable hard substrate outside the TVC, which is constituted of highly abundant hydrozoans (Aglaophenia sp.), antipatharians (Stichopates setacea and Antipathes furcata), and colonizing epibionts (e.g., Neopycnodonte cochlear). Three years after the eruption, species numbers at Tagoro were still low compared to those occurring at similar depths outside the TVC. The first dominant species at the TVC included a large proportion of common suspension feeders of the circalittoral and bathyal hard bottoms of the area, which could have exploited the uncolonized hard bottoms and the post eruptive fertilization of water masses.

Reunión Ibérica sobre Fallas Activas y Paleosismología (3ª. 2018. Alicante). - Texto en español con resumen y palabras claves en inglés y español El Mar de Alborán está afectado en su transversal central por una zona de deformación y actividad sísmica NNE-SSO. Tras las series sísmicas de 1993-94 y 2004, ha ocurrido una nueva serie en su sector meridional durante 2016-17 (evento principal Mw = 6.3, 25/01/2016), con epicentros agrupados en dos alineaciones. La septentrional, OSO-ENE, está asociada a mecanismos focales de falla inversa y caracterizada por una zona con depósitos recientes de transporte en masa. La meridional, NNE-SSO, se inicia con eventos localizados de 5 a 10 km al oeste de la falla de Al Idrisi, y posteriormente la zona de deformación se extiende hasta dicha falla. La deformación cercana a la superficie incluye fallas activas verticales y normales NO-SE, identificadas por primera vez, asociadas en profundidad a un segmento mayor de falla sinistra. El desarrollo de nuevas fallas puede generar sismos de mayor magnitud que en fallas preexistentes = The central transect of the Alboran Sea is affected by an NNE-SSW seismic activity band and deformation zone. After the seismic series of 1993-94 and 2004, a new series has occurred in its southern sector during 2016-17 (main event Mw = 6.3, 01/25/2016), with epicenters grouped in two alignments. The northern one, WSW-ENE, is associated with focal mechanisms of reverse faults and characterized by an area with recent mass transport deposits. The southern one, NNE-SSW, starts with localized events from 5 to 10 km west of the Al Idrisi fault, and then the seismicity zone extends towards this fault. The deformation near the surface includes active vertical and normal NW-SE faults, identified for the first time, associated in depth to a larger segment of sinistral fault. The development of new faults can generate earthquakes of greater magnitude than in preexisting faults. Instituto Andaluz de Ciencias de la Tierra, España Departamento de Geodinámica, Universidad de Granada, España Institut de Ciències del Mar, Consejo Superior de Investigaciones Científicas, España Real Instituto y Observatorio de la Armada, España Université Pierre et Marie Curie, Francia Université Mohammed Premier, Marruecos Instituto Geológico y Minero de España, España Centro Oceanográfico de Málaga, Instituto Español de Oceanografía, España Facultés de Sciences, Université Mohammed V, Marruecos Faculté des Sciences, Université Abdelmalek Essaadi, Marruecos Instituto Hidrográfico de la Marina, España Departamento de Ingeniería Cartográfica, Geodesia y Fotogrametría, Universidad de Jaén, España Centro de Estudios Avanzados en Ciencias de la Tierra, Universidad de Jaén, España

Report on the environmental monitoring (geophysics, seabed sampling, physical and chemical characteristics, and planton) made on the submarine volcano of Tagoro (El Hierro Islands) to evaluate the degree of affection and recovery on the marine ecosystem of the last volcanic eruption in the Canary region, making it extendable to other regions of the Canary Islands of possible hydrothermal or volcanological interest. In this sense, the "Enmedio" volcano has been investigated, between the islands of Gran Canaria and Tenerife., Instituto Español de Oceanografía

En el talud medio del golfo de Cádiz se desarrolla un sistema deposicional contornítico generado por la masa de Agua Mediterránea de Salida (Mediterranean Outflow Water; MOW) que interacciona con la topografía del fondo erosionando una serie de canales contorníticos en cuyos diques o levees se han identificados ondas sedimentarias oblicuas o paralelas a sus ejes. Estas ondas se han estudiado con mosaicos batimétricos adquiridos en varias campañas oceanográficas. Las ondas sedimentarias se encuentran entre 520 y 650 m de profundidad, sus longitudes axiales varían entre 360 m y 2400 m, sus alturas entre 3 m en posiciones alejadas del canal y 10 m en las ondas más proximales y sus longitudes de onda entre 175 y 600 m. Las velocidades de la MOW medida sobre estos campos de ondas oscilan entre 0,18 y 0,32 m/s. El origen de estas ondas podría explicarse por el desbordamiento de la parte superior del flujo canalizado, de forma que los cambios de dirección del canal harían que se “desprendiesen” las partes del flujo situadas por encima del canal, que iría perdiendo velocidad a medida que se separa de éste, justificándose así las direcciones de las ondas y la disminución de sus alturas a medida que aumenta la distancia al canal.

"Two kinds of biopolymer films were made from mucilage nopal xoconostle (Opuntia joconostle), corn starch,polyvinyl alcohol, chitosan and glycerol, which were prepared by the casting/solvent evaporation method. A comparisonbetween the formed films using the mucilage extract and the direct addition of mucilage to the polymer matrix wasdiscussed. The FTIR analysis revealed that both biofilms possessed a similar chemical structure. The thermal behaviour ofthe two kinds of films resulted very similar with an initial thermal decomposition temperature around at 156 °C. Opticaland SEM microscopies showed that the total solids present in the directly-added mucilage formed microphases in the bulkof the films. The mechanical properties disclosed that the higher the content of plasticisers the lower the elastic modulusand hardness values when mucilage was added directly."

AMERICAN GEOPHYSICAL UNION

AMERICAN GEOPHYSICAL UNION

We present a morphometric analysis of 41 mounded edifices located on the seafloor to the west of Canary Islands, using a 150 m resolution DEM and very high-resolution seismic profiles. In order to carry out morphometric computation a set of variables (slope, size and shape) were calculated using ArcGIS Analyst tools. A mapping cluster has been generated using Grouping Analyst ArcGIS Statistics toolset where seven differents morphometric groups have been distinguished. Four main types of edifice shapes have been identified within the seven morphometric groups. The first type is a single giant dome elevation that can be considered as an outlier mound. The second type is the most frequent and can be considered as the standard type mound on the Canary continental slope due to its intermediate morphology. They show extrusive seismic characteristics in seismic profiles. The third type is morphologically derived from type 2, representing steeper and higher mounds related with extrusive processes whereas the fourth type represents smoother and flatter mounds related to faulting. This study shows that an elaborated geomorphometry resolves between types of extrusive edifices from those under tectonic conditions Versión del editor

The mud volcanism in the Iberian and Moroccan margins of the Gulf of Cadiz is well known over more than a decade. Nevertheless, new structures and morphologies related to fluid venting are still discovered in the recent oceanographic cruise SUBVENT2 in 2014 along the Moroccan margin. Four new mud volcanoes have been identified along two sector of Moroccan margin. Two of them in the Eastern Moroccan Margin - EMF (Subvent and Rosco mud volcanoes), located in the upper slope between 350 and 500 m depth. The other two in the Western Moroccan Margin - WMF (Demetrio de Armas and Port Royal), located in the middle slope at 1800 m depth. The main aim of this paper is the morphological characterization of these new mud volcanoes using swath bathymetric data to analyze the relation between tectonic and sedimentary processes with multiparametric sounder and high resolution multichannel seismic profiles. The interpretation of these seismic profiles show that the source of expelled material of mud volcanoes in the EMF is buried under a sedimentary cover of contouritic deposits of 200 m thickness. A high sedimentation rate can cause an increase of pressure that could act as triggered of mud volcano edificies. In the WMF, the new mud volcanoes are developed related to thrust of the Allocthonous Unit of the Gulf of Cadiz. The origin of these structures is mainly related to de NW-SE tectonic compression . Versión del editor

The northeastern sector of the Gulf of Cadiz continental margin has been deeply studied the last two decades. The seafloor is characterized by the Gulf of Cadiz Contourite Depositional System, strong diapirism and seepage related to the mobility of the frontal units of the Gibraltar Arc. Since 2010 high resolution bathymetric data and high and very high resolution seismic reflection and parametric echosounder profiles have improved the resolution of the previous collected data set. These data allow to analyze the middle continental slope morphology and its shallow structure with the aim to know the active tectonic processes on the seafloor. Two types of structures have been considered: (a) anticline domes and (b) normal faults which produce linear scarps and tectonic depressions. The shallow tectonics in this region is mainly related to the high mobility of geological formations in the subsoil and their ductile mechanical behaviour. Versión del editor

Technical advances in hydrographic studies of the seafloor and the progressive use of these techniques in oceanographic expeditions with scientific objectives, is generating greater collaborations between the hydrographic and oceanographic institutions. Coordination between the different institutions and the use of IHO criteria in the acquisition of bathymetric data in oceanographic expeditions, allow regional hydrographic offices to have an additional source of data for the improvement of the navigation charts. Meanwhile the Oceanographic Institutions will benefit by having validated bathymetric data of high precision. This product is of great interest in studies of submarine geological hazards where is necessary to have a very detailed knowledge of the seabed to determine possible morphological changes associated with the risk processes and the possible active structures. In addition, monitoring of active volcanoes need to have a good knowledge of changes in the physico-chemical properties of the water column, the possible changes in low intensity emissions (hot water, gas) can be detected with these studies in the overlying water masses. Versión del editor

The Passage of Lanzarote is an example of a wide oceanic corridor. It extends between the eastern Canary Islands and the Western Africa continental margin. Seafloor morphology of this passage has been analyzed with the aim to know the morphogenetic processes related to both the oceanography and the geology. Multibeam bathymetric data and high and very high resolution seismic profiles obtained in the SUBVENT2 cruise have been used. Five main morphological groups were analyzed: (a) Volcanic or diapiric submarine hills; (b) Tectonic features on the continental slope (linear scarps and a rhomboid-like depression) related to normal faults at the top of buried diapirs; (c) Giant circular depressions initially triggered by submarine venting at the top of diapirs; (d) Sedimentary instabilities and canyons (gullies, canyons, mass transport deposits) that are present specially on the Fuerteventura-Lanzarote ridge must be related to the high energy geological processes, both constructive and dismantling, associated to the evolution of these volcanic domains; and (e) Contouritic features both erosive (central channel, contourite channels) and depositional (mounded and plastered drifts) that occur in the central part of the bottom surface of the passage, and are generated by the interaction of the MW and the interface MW-AAIW with the seafloor. Versión del editor

The study of turbidity plumes developed in front of the river mouth, have an increasing scientific interest due to its contribution to infralittoral sediment transport and deposition. River plume evolution and deposition in submarine fans related to environmental constrains could be interpreted by the analysis of suspended particulate matter (SPM) retained during the filtering process. In this study, a new methodology approach to obtain quantitative results in sediment filters, using custom digital image processing techniques, is presented and some promising preliminary results are obtained. This procedure could avoid time-consuming during SPM analysis allowing an easy way to obtain fast and quantitative information, which might lead to a better interpretation and comprehension of factors involved in the evolution of riverine turbidity plumes. Versión del editor

Mud volcanism represents an important migration pathway for methane and other gases from deeper reservoirs to the surface; however most submarine sources remain poor quantified. During SUBVENT2 cruise, water column over several mud volcanoes were surveyed for gas seepage characterization. Water samples of ROV Niskin and Rosette-CTD Niskin bottles were recovered above the Bonjardim, El Cid, Las Negras, Mercator, Algacel, Mvseis, Madrid and Yuma mud volcanoes, and at three newly discovered, mud volcano like structures, to quantify overall gases release fluxes from seabed. CO2 and CH4 concentrations were measured by potentiometric titration and using a gas chromatograph, respectively, in order to understand the relationship between physicochemical and geological processes. Gases concentrations decreased from shallower to deeper mud volcanoes. Values varied widely within 50 to 200 nM for CH4 and between 400 to 1500 μatm for fCO2. Greenhouse gases variations were large influenced by water column depth, temperature, salinity and possibly by anaerobic oxidation of methane (AOM). Our observations suggest that the emission of methane and carbon dioxide from the mud volcanoes structures studied here may be relevant at the present as a part of the carbon global cycle. Versión del editor

The Gulf of Cadiz is located in the boundary of two lithospheric plates, this tectonic activity promote fluid rich hydrocarbon emissions from subsurface reservoirs and the formation of several mud volcanoes. The seabed and sedimentological heterogeneity, the complex oceanographic circulation, and the low fishing activity in certain areas may promote high biodiversity and complex habitats (habitat 1170 and 1180, Natura 2000). Environmental variables (fishing activity, substrate types, near bottom currents) and fauna collected with beam-trawl have been compared for several mud volcanoes and adjacent bottoms in order to understand the spatial distribution of both habitats and environmental/anthropogenic variables. The faunistic samples yielded high abundances, biomass and species richness in Gazul, Pipoca and Chica but low ones in Anastasya. In relation to environmental variables and fisheries activity, there is a strong correlation with the substrate type, depth, salinity and near-bottom current as primary variables influencing the distribution of habitats of different mud volcanoes. In this context, high species richness, abundance and biomass was found in areas with authigenic carbonates, coarse sediments, high near-bottom current speed, low salinities and low fishing activity.

The continental slope of the Canary Islands volcanic province is characterized by the occurrence of several seamounts and large landslides that have been widely documented. A detailed morphological study of the Echo seamount has been done by using multibeam bathymetry, backscatter data and very high resolution seismic profiles. The seamount shape, the occurrence of a flat summit and the presence of characteristics morphological features on the summit and along the flanks as volcanic cones, ridges, slides scars, gullies and channels, among others, have allowed establishing differences in its evolution. The analysis of these seamount features let to think that the seamount could be an oceanic island that becomes eroded and sank to its present depth. Recent geological processes observed at the base of the seamount let to establish different features and morpho-sedimentary units. They have been interpreted as the result of dismantling processes of the flanks although they have also related to the massive slope instabilities developed on the continental slope. Versión del editor

Extrusive edifices and structural reliefs, catalogued as mounds and located on the seafloor to the west of Canary Islands were analyzed by acoustic data obtained with multibeam and parametric echosounders during several oceanographic expeditions. They were carried out at deep waters, from 4800 to 5200 m, and they have allowed characterizing 41 newly discovered submarine structures which occur either as isolated edifices or clustered mounds. These features have circular to elongated shapes with diameters of 2-24 km and relief heights of 10 to 250 m, showing different flank slopes of 2-50°. They generally display mounded forms and show morphological elements as ridges, near-circular rock outcrops, depressions and fault scarps together with mass flow and slide deposits located at the vicinity of the edifices. Two types of extrusive features are evidenced by the morphological and seismic data analyses, the first one probably corresponds to high velocity extrusions that reach the seafloor surface and the second one is probably formed by the combination of faulted structures and low velocity extrusions that produce singular domes in the shallower sedimentary records. Based on both analyses, extrusive phenomena represent the dominant mechanism for mound field evolution in the Canary lower slope region. Versión del editor

Contourite drifts are one the main morphosedimentary features in the Alboran Sea and their sediments are important archives of the past oceanographic conditions and sedimentary processes. The end-member modelling approach lets to decompose multimodal grain-size distribution into genetically meaningful subpopulation that may be related to different sediment transport mechanisms and source areas. Three end-members have been identified in the contourite drift and moat system located at the southern side of the Dijbouti Ville seamount that have been interpreted in terms of sediment sources. Two end-members point to an eolian source and comprise fine silt (EM1) and coarse silt (EM2) as modal grain-sizes, characterized by high and low contents, respectively, of terrigenous elements (Al, Si, Ti and K). The third end-member (EM3) indicates a fluvial origin and is mainly defined by a clay modal grain-size of intermediate and homogeneous content in terrigenous elements. Downcore variation of the relative proportion of these EMs can be used to decipher paleocenographic and paleoclimatic conditions in the Alboran Sea. Versión del editor

New high-quality high-resolution bathymetric data along the northeastern slope of the Gulf of Cadiz continental margin reveals three gullies fields. The morphological and morphometric features of these gullies have been studied. The following morphometric variables have been measured in every gully in order to make a quantitative morphological analysis: width, depth, thalweg length, straight line length, area, sinuosity index, width/depth ratio, and stream order. The morphological characterization of the gullies suggests that these morphologies vary with the local physiography (concavity/convexity of the slope), the sediment transport efficiency, tectonic control and oceanographic regime. Versión del editor

The seabed morphology and the sub-bottom characteristics of a sector of the Gulf of Cádiz continental slope have been analyzed from different data sets. The morphological characteristics, the type of sediments and dominant benthic species of Gazul mud volcano and adjacent areas have been studied. The morphological characteristics identified were grouped in fluid escape related features, bottom current features, mass movement features, structural features and biogenic related features. Additionally, dominant benthic species associated to fluid escape and seepage, hard substrates or soft bottoms have also been indicated in these features. A bottom current velocity analysis allowed relating the morphological features with the different sedimentary and oceanographic processes as well as the benthic habitats and that currently occur in the mud volcano and nearby areas. The major factor controlling these features and their associated benthic habitats is the interaction of deep water masses with the seafloor topography. At high velocities, authigenic carbonates can be exhumed and colonized by sessile suspensivorous species associated with hard substrates such as cold-water corals, anthipatarians and large sponges. Mounds and diapiric ridges are found on the depressions and they could be relict structures. Living corals have been found on raised zones, revealing different oceanographic condition and strong enough currents to favour the availability of nutrients and organic particles. Chemosymbiotic organisms are very scarce at the summit and old remains of Lucinoma asapheus indicating past higher seepage activity. Versión del editor

Five different groups of gullies have been distinguished along the northeastern slope of the Gulf of Cádiz using geostatistical analysis. A Grouping Analyst has been carried out to six morphological variables of the gullies: area, straight line length, width/depth ratio, width, depth and stream order. The spatial distribution of the identified five groups and their mean characteristics have allowed us to propose an evolutionary model for the two zones of the upper continental slope. This model is related to the local physiography, the sediment supply, the tectonic control and the oceanographic regime. Versión del editor

The study of turbidity plumes developed in front of the river mouth, have an increasing scientific interest due to its contribution to infralittoral sediment transport and deposition. River plume evolution and deposition in submarine fans related to environmental constrains could be interpreted by the analysis of suspended particulate matter (SPM) retained during the filtering process. In this study, a new methodology approach to obtain quantitative results in sediment filters, using custom digital image processing techniques, is presented and some promising preliminary results are obtained. This procedure could avoid time-consuming during SPM analysis allowing an easy way to obtain fast and quantitative information, which might lead to a better interpretation and comprehension of factors involved in the evolution of riverine turbidity plumes.

The seabed morphology and the sub-bottom characteristics of a sector of the Gulf of Cádiz continental slope have been analyzed from different data sets. The morphological characteristics, the type of sediments and dominant benthic species of Gazul mud volcano and adjacent areas have been studied. The morphological characteristics identified were grouped in fluid escape related features, bottom current features, mass movement features, structural features and biogenic related features. Additionally, dominant benthic species associated to fluid escape and seepage, hard substrates or soft bottoms have also been indicated in these features. A bottom current velocity analysis allowed relating the morphological features with the different sedimentary and oceanographic processes as well as the benthic habitats and that currently occur in the mud volcano and nearby areas. The major factor controlling these features and their associated benthic habitats is the interaction of deep water masses with the seafloor topography. At high velocities, authigenic carbonates can be exhumed and colonized by sessile suspensivorous species associated with hard substrates such as cold-water corals, anthipatarians and large sponges. Mounds and diapiric ridges are found on the depressions and they could be relict structures. Living corals have been found on raised zones, revealing different oceanographic condition and strong enough currents to favour the availability of nutrients and organic particles. Chemosymbiotic organisms are very scarce at the summit and old remains of Lucinoma asapheus indicating past higher seepage activity.

We present a morphometric analysis of 41 mounded edifices located on the seafloor to the west of Canary Islands, using a 150 m resolution DEM and very high-resolution seismic profiles. In order to carry out morphometric computation a set of variables (slope, size and shape) were calculated using ArcGIS Analyst tools. A mapping cluster has been generated using Grouping Analyst ArcGIS Statistics toolset where seven differents morphometric groups have been distinguished. Four main types of edifice shapes have been identified within the seven morphometric groups. The first type is a single giant dome elevation that can be considered as an outlier mound. The second type is the most frequent and can be considered as the standard type mound on the Canary continental slope due to its intermediate morphology. They show extrusive seismic characteristics in seismic profiles. The third type is morphologically derived from type 2, representing steeper and higher mounds related with extrusive processes whereas the fourth type represents smoother and flatter mounds related to faulting. This study shows that an elaborated geomorphometry resolves between types of extrusive edifices from those under tectonic conditions

Mud volcanism represents an important migration pathway for methane and other gases from deeper reservoirs to the surface; however most submarine sources remain poor quantified. During SUBVENT2 cruise, water column over several mud volcanoes were surveyed for gas seepage characterization. Water samples of ROV Niskin and Rosette-CTD Niskin bottles were recovered above the Bonjardim, El Cid, Las Negras, Mercator, Algacel, Mvseis, Madrid and Yuma mud volcanoes, and at three newly discovered, mud volcano like structures, to quantify overall gases release fluxes from seabed. CO2 and CH4 concentrations were measured by potentiometric titration and using a gas chromatograph, respectively, in order to understand the relationship between physicochemical and geological processes. Gases concentrations decreased from shallower to deeper mud volcanoes. Values varied widely within 50 to 200 nM for CH4 and between 400 to 1500 μatm for fCO2. Greenhouse gases variations were large influenced by water column depth, temperature, salinity and possibly by anaerobic oxidation of methane (AOM). Our observations suggest that the emission of methane and carbon dioxide from the mud volcanoes structures studied here may be relevant at the present as a part of the carbon global cycle.