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Geomorphic evolution of tectonically active continental margins is the result of the interplay of deformation and sedimentary structures. Iberian Peninsula, located in the present-day NW-SE convergent Eurasia-Africa plate boundary, is mainly deformed in the northern Cantabrian margin (NE Atlantic) and in the southern, both Alboran and Gulf of Vera margins (SW Mediterranean). These margins develop elongated highs and basins roughly parallel to the margins. Moreover, faults and volcanic structures affect the southern Iberia margin. All these deformation structures are responsible for the regional configuration and physiographic components of the margin, seafloor topography, as well as entry points of sediment and pathways of the alongslope (bottom currents) and downslope (mass-transport and gravity flows) sedimentary processes. The deformation structures condition the distribution of deep-sea bottom currents and their sedimentary geomorphic impact is regionally variable during the Quaternary. Contourite features are dominant in the Alboran Sea to the extent that their distribution conditions the physiography. This significant action of bottom currents is linked to the semi-enclosed basin configuration that favours the confinement of the Mediterranean waters. Contrasting, in the Cantabrian and Aguilas open margins, bottom currents are topographically steered by the highs and form local contourite features. Deformation structures also influence the downslope sedimentary processes. Mass-transport and sediment gravity flow features are mostly shaping the Cantabrian and Gulf of Vera margins during the Quaternary. Their occurrence is related to the overstepping or tectonic tilting of the margins, shelf-indenting canyons and narrow shelves. Contrasting, those features are less extended in the Alboran Sea, where their formation is related to seismicity, overstepping of highs, fluid dynamics and turbidite systems. These results indicate that the regional tectonic style of defo

We present a multidisciplinary study of morphology, stratigraphy, sedimentology, tectonic structure, and physical oceanography to report that the complex geomorphology of the Palomares continental margin and adjacent Algerian abyssal plain (i.e., Gulf of Vera, Western Mediterranean), is the result of the sedimentary response to the Aguilas Arc continental tectonic indentation in the Eurasian–Africa plate collision. The inden tation is imprinted on the basement of the margin with elongated metamorphic antiforms that are pierced by igneous bodies, and synforms that accommodate the deformation and create a complex physiography. The basement is partially covered by Upper Miocene deposits sealed by the regional Messinian Erosive Surface characterized by palaeocanyons that carve the modern margin. These deposits and outcropping basement highs are then covered and shaped by Plio-Quaternary contourites formed under the action of the Light Intermediate and Dense Deep Mediterranean bottom currents. Even though bottom currents are responsible for the primary sedimentation that shapes the margin, 97% of this region's seafloor is affected by mass-movements that modified contourite sediments by eroding, deforming, faulting, sliding, and depositing sediments. Mass-movement processes have resulted in the formation of recurrent mass-flow deposits, an enlargement of the submarine canyons and gully incisions, and basin-scale gravitational slides spreading above the Messinian Salinity Crisis salt layer. The Polopo, Aguilas and Gata slides are characterized by an extensional upslope domain that shapes the continental margin, and by a downslope contractional domain that shapes the abyssal plain with diapirs piercing (hemi)pelagites/sheet-like turbidites creating a seafloor dotted by numerous crests. The mass movements were mostly triggered by the interplay of the continental tectonic indentation of the Aguilas Arc with sedimentological factors over time. The indentation, which involves t

This article offers an overview of the main sedimentary systems defining the geomorphology of deep sea environments from low to high latitudes. Mass-transport deposits, turbidite systems, contourites, volcaniclastic aprons, glacial trough mouth systems, carbonate mounds and other bathyal systems, such as pelagites, hemipelagites, mid-ocean channels and polymetallic mineral deposits, are presented with special attention to their morphology, sediments, processes and controlling factors. The integration of the main systems on the continental margins and adjacent abyssal plains in the North Atlantic and westernmost Mediterranean allows to characterize different sedimentation models.

The seafloor of the Alboran Sea reflects its complex tectonic, sedimentary, and oceanography dynamics as a consequence of the geological context, involving interaction between the Eurasian and African plates, and oceanographic context, as it is where the Atlantic and Mediterranean waters meet. Their physiography has a semi-enclosed configuration characterized by two margins (the Spanish Iberian and North Africa—mostly Moroccan margins) enclosing deep basins. Tectonic activity is mainly attested by folds and faults that predominantly affect the central and eastern seafloor sectors, as well as numerous seamounts and fluid-flow features (pockmarks, mud volcanoes, and diapirs) that dot the seafloor. The sedimentary and oceanographic processes allow us to distinctly define two principal environments in the Alboran Sea: the shallow proximal margin (continental shelf); and the deep distal margin (continental slope and base of the slope) with the adjacent sub-basins. The shelf mostly comprises prodeltaic and infralittoral prograding wedges, with local bedform fields, submarine valleys, and wave-cut terraces. Coastal and fluvio-marine sedimentary processes, acting since the last glacial period, are responsible for these features. The deep marine environment is characterised by the ubiquity of contourites, whose continuity is interrupted by turbidite systems, canyons, and landslides. The alongslope action of the Mediterranean waters and their interfaces with the Atlantic water has been the main process governing transport, seafloor reworking, and sedimentation of contourites. Mass-movement processes are responsible for the formation of: (1) turbidite systems—turbidity flows and mass flows were dominant during the last glacial sea-level lowstand, evolving to dilute gravity flows during present interglacial high stand; and (2) landslides—the main triggering factors comprising over-steepening, seismicity, under consolidation due to overpressure by interstitial fluids, stratigrap

Offshore geological hazards can occur in any marine domain or environment and represent a serious threat to society, the economy, and the environment. Seismicity, slope sedimentary instabilities, submarine volcanism, fluid flow processes, and bottom currents are considered here because they are the most common hazardous processes; tsunamis are also examined because they are a secondary hazard generated mostly by earthquakes, slope instabilities, or volcanic eruptions. The hazards can co-occur and interact, inducing a cascading sequence of events, especially in certain contexts, such as tectonic indentations, volcanic islands, and canyon heads close to the coast. We analyze the key characteristics and main shortcomings of offshore geological hazards to identify their present and future directions for marine geoscience investigations of their identification and characterization. This review establishes that future research will rely on studies including a high level of multidisciplinarity. This approach, which also involves scientific and technological challenges, will require effective integration and interplay between multiscale analysis, mapping, direct deep-sea observations and testing, modelling, and linking offshore observations with onshore observations

A new basin-scale comprehensive view of contourite features, turbidite systems, and mass-wasting deposits comprising the Spanish and Moroccan margins and basins of the Alboran Sea has been achieved after a new detailed seismic stratigraphic analysis and the construction of sedimentary maps for the Pliocene and Quaternary sedimentary units. Multiple contourite systems were defined in this sea: i) the Intermediate Mediterranean contourite system (IMCS), formed under the action of the LMW on the Spanish continental margin; ii) the Deep Mediterranean contourite system (DMCS), formed under the action of the DMW and made up of contourites mostly found on the Moroccan margin and annex sub-basins; and iii) the Atlantic contourite system (ACS), shaped by the AW and its interfaces with the LMW and DMW on the uppermost continental slopes of both margins. The contourite features (drifts, moats, channels and terraces) coexist during the various stages of the Plio-Quaternary with turbidite systems showing different onsets and cessations in activity, and with masswasting deposits. In this work, the temporal and spatial distributions of contourite and turbidite systems can be considered as proxies to deduct the long-term impacts of bottom-current circulations and related processes, and ultimately allowed to decipher past bottom-current dynamics and the multiple factors controlling PlioQuaternary sedimentation in the Alboran Sea.

Since the Miocene, the thinned continental crust below the Alboran Sea and its overlying sedimentary cover have been undergoing deformation caused by both convergence of Eurasia and Africa and by deep processes related to the Tethyan slab retreat. Part of this deformation is recorded at the Xauen and Tofiño banks in the southern Alboran Sea. Using swath bathymetry and multichannel seismic reflection data, we identified different stages and styles of deformation. The South Alboran Basin is made up of Early Miocene to Pliocene sedimentary layers that correlate with the West Alboran Basin depocenter and are dominated by E‐W trending folds and thrusts. The Xauen and Tofiño Banks first recorded the phase of extension and strike‐slip movement during the slab retreat, followed by the phase of compressional inversion since the Tortonian and are now structured by tight folds, thrusts, and mud bodies. This study proposes that the Banks were located on the southern‐inherited Subduction Tear Edge Propagator (STEP) fault related to the westward migration of the Alboran domain during the Miocene. The STEP fault zone, acting as a boundary between the African block and the Alboran block, was located along the onshore Jebha‐Nekor fault and the offshore Alboran Ridge and the Yusuf fault zone. Thick‐skinned and thin‐skinned shortening occurred when slab retreat stopped, and inversion began. The present‐day style of the deformation seems to be linked to a decollement level made of undercompacted shale on top of the Ghomaride complex.

This paper presents the stratigraphic architecture of the lobe complex (LC) of the distal Almeria turbidite system over the last 575 ka based on very high-resolution data (seismic parametric sub-bottom profiles, bathymetry and stable oxygen isotope core data). Its depositional architecture suggests the 575 ka oldest lobe represents a lobe system, which is essentially organized in vertical stacking of channel-levee/lobes. Their morpho-sedimentary characteristics point to: (i) this turbidite system roughly matches that of mixed sandmud composition systems; and (ii) the lateral relocation of turbidites may be conditioned by factors such as the sediment load, the energy of gravity flows, related avulsion processes and the local morphological confinement. The detailed seismofacies analysis enabled the identification of channel-levee/lobes, mass-transport deposits and hemipelagites formed over the last 269 ka. Their lateral and vertical distribution suggests that an increased submarine canyon activity and mass-movements took place during lowstand stages (MIS 8, MIS 6, MIS 4 and MIS 2) whereas hemipelagic settling dominated during the highstand stages (MIS 7 and MIS 5), Se presenta la arquitectura estratigráfica del complejo de lóbulo (LC) del sistema turbidítico distal de Almería de los últimos 575 ka basada en datos geológicos de muy alta resolución (perfiles sísmicos paramétricos, batimetría e isotopos estables de oxígeno). Su arquitectura deposicional sugiere que el lóbulo más antiguo (575 ka) está organizado por el apilamiento vertical de complejos de canal-dique/ lóbulo. Sus características morfo-sedimentarias apuntan a: (i) su coincidencia con las de los sistemas mixtos de composición areno fangosa y que (ii) la reubicación lateral de los depósitos turbidíticos pudo estar condicionada por la carga de sedimento, la energía de los procesos gravitacionales, los procesos de avulsión y el confinamiento local. El análisis detallado de las sismofacies permite la identificación de lóbulos canalizados, depósitos de transporte en masa, y hemipelagitas formados durante los últimos 269 ka. Su distribución lateral y vertical sugiere que la actividad del cañón submarino y los movimientos en masa fueron mayores durante las etapas de bajo nivel del mar (MIS 8, MIS 6, MIS 4 y MIS 2) y la sedimentación dominante sería hemipelágica durante las etapas de alto nivel del mar (MIS 7 y MIS 5).

The Djibouti Ville Drift is part of a contourite depositional system located on the southern side of the Djibouti Ville Seamount in the Alboran Sea (Western Mediterranean). The sedimentary record of a core located in the drift deposits has been characterized to achieve the possible sediment sources for the Saharan dust supply and the paleocurrent variability related to Mediterranean intermediate waters for the last 133 kyr. Three end-member grain-size distributions characterize the sediment record transported by the bottom current to address the different aeolian populations, i.e., coarse EM1, silty EM2, and fine EM3. For these particles, the most likely source areas are the Saharan sedimentary basins and deserts, as well as the cratonic basins of the Sahara-Sahel Dust Corridor. The prevalence of these main source areas is shown in the core record, where a noticeable change occurs during the MIS 5 to MIS 4 transition. Some punctual sediment inputs from the seamount have been recognized during sea-level lowstand, but there is no evidence of fluvial supply in the drift deposits. The paleocurrent reconstruction allows the characterizing of the stadial and cold periods by large increases in the mean sortable silt fraction and UP10, which point to an enhanced bottom current strength related to intermediate water masses. Conversely, interglacial periods are characterized by weaker bottom current activity, which is associated with denser deep water masses. These proxies also recorded the intensified Saharan wind transport that occurred during interstadial/stadial transitions. All these results point to the importance of combining sediment source areas with major climatic oscillations and paleocurrent variability in palaeoceanographic sedimentary archives, which may help to develop future climate prediction models.

This is an interdisciplinary study that combines morphoseismics, sedimentology and numerical modelling to elucidate at different scales of resolution the influence of alongslope processes on the turbidite systems (TSs) and canyons in the Alboran Sea (southwestern Mediterranean). Nine TSs are mapped in the Spanish margin (La Linea, Guadiaro, Baños, Torrenueva, Fuengirola, Salobreña, Sacratif, Calahonda and Almeria) and two in the Alboran Ridge (Piedra Escuela and Al-Borani). In the Moroccan margin, there are only two canyons (Ceuta and Nekor). Distinctive morphoseismic and sedimentological signatures from TSs and canyons have enabled three regional models of alongslope influence to be distinguished: a) Alongslope processes are dominant. This scenario characterizes the canyons of the Moroccan margin. The diagnostic signature is the lack of leveed channels and lobes at the Ceuta and Nekor Canyon mouths. b) Different degrees of interplay exist between alongslope and downslope processes. This scenario occurs in the TSs of the western Spanish margin. Here, the alongslope influence on TSs (La Linea, Guadiaro, Baños, Torrenueva and Fuengirola) is evidenced by the lack of overbank deposits in the La Linea and Guadiaro Canyons and an alongslope trend in the morpho-architecture of the channelized lobes and in the textural distribution of canyon/channel deposits (mass-flow deposits and turbidites). Both signatures indicate sandier TSs as well as Bouma turbidite sequences lacking the finest levels towards the Strait of Gibraltar. Local intercalations of contourites are also present in the Guadiaro lobe deposits. c) Downslope processes are dominant. This scenario characterizes the TSs of the eastern and central Spanish margin and Alboran Ridge. There, TSs seem to be controlled solely by the characteristics of the downslope gravity flows that transport sediment. The hydrodynamic and sediment dispersion models confirm that the main oceanographic factors governing the variable along

We have investigated the origin of morphological depressions (circular-elliptical depressions, amphitheatre-shaped escarpments and valleys) on the Guadalquivir Bank uplifted area (Gulf of Cadiz middle slope). This work is based on swath bathymetry and high- and mid-resolution reflection seismic datasets. Depressions occur on the distal (depositional) sector of the Gulf of Cadiz Contourite Depositional System, which has been developed under the influence of the Mediterranean Outflow Water (MOW). The Guadalquivir Bank is a NE-oriented relief that was uplifted along the Neogene and Quaternary. It forms the southern limit of the Bartolomeu Dias and Faro Sheeted Drift (SD) plateaus that are separated by the NW-trending Diego Cao Contourite Channel. Circular-elliptical depressions occur on the Bartolomeu Dias SD plateau, aligned parallel to the rim of the Diego Cao Channel. Irregular, crescent-shaped depressions occur to the SE of the study area and a valley surrounds the Guadalquivir Bank. The origin of these features is interpreted as the result of the interplay between oceanographic, mass-wasting, tectonic and fluid-escape processes. Four stages define the development of these features: 1) Onset of a contourite mounded drift associated with a proto-Diego Cao moat originated by a weak MOW circulation as it interacted with the structural features of the Guadalquivir Bank during the Lower Pliocene; 2) Evolution to a more complex multi-crest drift and moat system, probably as a result of an enhanced MOW and increased deformation of the underlying structures during the Upper Pliocene-Early Quaternary; 3) Event of enhanced tectonic activity that provoked widespread mass-wasting events along middle slope sheeted drift plateaus during the Mid Pleistocene. It was recorded in a prominent erosive surface under the present-day Diego Cao channel western rim and numerous slide scars displaying amphitheatre shapes on the limits of the plateaus; 4) Final stage (Late Quaternary) when t

This study focuses on the Alboran Sea area (Westernmost Mediterranean), where a seismic analysis of the Pliocene and Quaternary stratigraphy was conducted in the Alboran Sea (Westernmost Mediterranean) using ~2000 profiles consisting of single and multi-channel seismic records. The seismic facies and architectural analysis of the deposits evidence the presence of bottom-current deposits (plastered, sheeted, elongated-separated and confined monticular drifts) and associated erosive features (terraces, scarps, moats and channels). Many of these deposits were previously considered to be open slope turbidite deposits which have now been reinterpreted as contourites.The contourite features have developed under the continuous influence of Mediterranean water masses, after the opening of the Strait of Gibraltar (roughly divided into light and dense Mediterranean waters), with plastered drifts dominating on the Spanish and Moroccan continental slopes, and sheeted drifts infilling the subbasins. The location and growth of contourite features have been mainly controlled by two main factors: i) tectonics, which has governed the relocation of the main pathways of the water masses; and ii) climate, which has influenced both water mass conditions and the depth of interfaces, as well as hinterland sediment sources, conditioning the morphoseismic characteristics of the drifts (facies and geometry) and terrace formation (dimensions). The mapping of the contourite facies through time has allowed defining three main scenarios for deep water circulation since the opening of the Strait of Gibraltar, which are: i) Atlantic Zanclean flooding; ii) the Pliocene sea, with two different stages caused by the progressive relocation of flow pathways; and iii) the Quaternary sea, with well defined characteristics and mostly stable flow pathways for the AW, and light and dense Mediterranean waters.This work lead us to consider the geologic framework characterizing the Alboran Sea may have played a

This work aims to analyze the interaction between alongslope contouritic and downslope gravitational processes in the Alboran Sea. Recent results (Juan et al., 2012, 2016) demonstrated that the Pliocene and Quaternary stratigraphic architecture is mostly made up the vertical stacking of contourites interrupted by turbidite systems (TSs). The accurate analysis of all available seismic profiles has revealed several morpho-sedimentary signatures produced by the interaction of the Atlantic Water (AW) and Mediterranean waters (MWs) with the gravity flows in the Pliocene and Quaternary sedimentary record, as well as on the present-day seafloor. Different levels of interaction have been identified and they move between two-end-members: from bottom currents dominating gravity flows, to gravity flows dominating bottom currents. In between these extreme cases, a range of possibilities can occur. First, downslope and alongslope processes can alternate, with vertical and cyclic stacking of both types of deposit. Second, these processes can be balanced, allowing the simultaneous outbuilding of contourites and gravity flow deposits. Last, bottom currents can influence gravity flows. This last interaction is the most common in the Alboran Sea, resulting in the migration of the fan deposits in the direction of the dominant current, and also with effects on the architecture of the turbidite fans, and on their sedimentary composition (grain size). The different levels of interaction change in space and time. These changes have controlled the different depositional architecture displayed by the Spanish and Moroccan margins and the lateral changes along the Spanish margin as a consequence of the different architecture of the turbidite systems. Although interaction occurs in both margins, it is especially complex and varied on the Spanish margin, where the alongslope action is related to the AW, the light intermediate and the dense deep Mediterranean waters (LMw and DMw, respectively).

Our understanding of bottom-currents and associated oceanographic processes (e.g., overflows, barotropic tidal currents) including intermittent processes (e.g., vertical eddies, deep sea storms, horizontal vortices, internal waves and tsunamis) is rapidly evolving. Many deep-water processes remain poorly understood due to limited direct observations, but can generate significant depositional and erosional features on both short and long term time scales. This paper represents a review work, which describes for the first time these oceanographic processes and examines their potential role in the sedimentary features along the Iberian continental margins. This review explores the implications of the studied processes, given their secondary role relative to other factors such as mass-transport and turbiditic processes, and highlights three major results: a) contourite depositional and erosional features are ubiquitous along the margins, indicating that bottom currents and associated oceanographic processes control the physiography and sedimentation; b) the position of interfaces between major water masses and their vertical and spatial variation in time specifically appears to exert primary control in determining major morphologic changes along the slope gradient, including the contourite terraces development; and c) contourites deposits exhibit greater variation than the established facies model suggests. Therefore, a consistent facies model however faces substantial challenges in terms of the wide range of oceanographic processes that can influence in their development. An integrated interpretation of these oceanographic processes requires an understanding of contourites, seafloor features, their spatial and temporal evolution, and the near-bottom flows that form them. This approach will synthesize oceanographic data, seafloor morphology, sediments and seismic images to improve our knowledge of permanent and intermittent processes around Iberia, and evaluate their co

We present an interdisciplinary study of the geomorphology, sedimentology and physical oceanography of the Alboran Sea (south-western Mediterranean Sea) to evaluate the potential role of bottom currents in shaping the Spanish and Moroccan continental margins and adjacent basins. Bathymetric and seismic data have allowed the recognition of the contourite deposits, including depositional (plastered, sheeted, channel-related, mounded confined, elongated and separated drifts), erosive (moats, channels and furrows) and mixed (terraces and scarps) features. Hydrographic data offer new insights into the distribution of the Mediterranean water masses, and reveal that bottom circulation of the Western Intermediate Water (WIW) and the Levantine Intermediate Water (LIW) interact with the Spanish slope, and the Western Mediterranean Deep Water (WMDW) on the Moroccan slope, Spanish base-of-slope and deep basins. The integration of distinct datasets and approaches allows a proposal of a new sedimentary model for the Alboran Sea that details the significance of bottom current processes in shaping deep-sea morphology. This model considers the bottom circulation of water masses governs physiography, that interface positions of water-masses with contrasting densities sculpt terraces on a regional scale, and that the morphologic obstacles play an essential role in the local control of processes and water-mass distributions. Our findings demonstrate the pivotal role of bottom water circulation in seafloor shaping and sedimentary stacking patterns for continental margins, establishing a new outlook for future studies of deep marine sedimentation.

Our understanding of the role of bottom currents and associated oceanographic processes (e.g, overflows, barotropic tidal currents) including intermittent processes (e.g, vertical eddies, deep sea storms, horizontal vortices, internal waves and tsunamis) is rapidly evolving. Many deep-water processes remain poorly understood due to limited direct observations, but may generate significant depositional and erosional features on both short-and long-term time scales. This paper describes these oceanographic processes and examines their potential role in the sedimentary features around the Iberian margin. The paper explores the implications of the processes studied, given their secondary role relative to other factors such as mass-transport and turbiditic processes. An integrated interpretation of these oceanographic processes requires an understanding of contourites, sea-floor features, their spatial and temporal evolution, and the near-bottom flows that form them. Given their complex, three-dimensional and temporally-variable nature, integration of these processes into sedimentary, oceanographic and climatological frameworks will require a multidisciplinary approach that includes Geology, Physical Oceanography, Paleoceanography and Benthic Biology. This approach will synthesize oceanographic data, seafloor morphology, sediments and seismic images to improve our knowledge of permanent and intermittent processes around Iberia, and evaluate their conceptual and regional role in the sedimentary evolution of the margin. © 2015, Instituto Geologico y Minero de Espana. All rights reserved, El conocimiento del papel de las corrientes de fondo y los procesos oceanográficos asociados (overflows, corrientes de marea barotrópicas, etc), incluyendo procesos intermitentes (eddies, tormentas profundas, ondas internas, tsunamis, etc), está evolucionando rápidamente. Muchos de estos procesos son poco conocidos, en parte debido a que las observaciones directas son limitadas, si bien pueden generar importantes rasgos deposicionales y/o erosivos a escalas temporales de corto o largo periodo. Este artículo describe dichos procesos oceanográficos y examina su influencia en la presencia de rasgos sedimentarios alrededor del margen Ibérico. El trabajo discute las implicaciones de dichos procesos y el papel secundario que juegan en relación a otros factores tales como los procesos de transporte gravitacionales en masa y los turbidíticos. Para un mejor conocimiento de la sedimentación marina profunda, y en concreto de los sistemas contorníticos, se requiere de una interpretación de estos procesos oceanográficos, cuál es su evolución espacial y temporal, cómo afectan a las corrientes de fondo y cómo se ven afectados por la topografía submarina. Sin embargo, dada su complejidad y su variable naturaleza tridimensional y temporal, es necesario que estos procesos se integren en un marco sedimentológico, oceanográfico y climatológico con un enfoque multidisciplinar que incluyan la Geología, la Oceanografía Física, la Paleoceanografía y la Biología bentónica. Esta integración requiere de una mayor compilación de datos oceanográficos, de un mejor conocimiento de la morfología del fondo marino, y de una mejor caracterización de los sedimentos en ambientes profundos. Todo ello permitirá mejorar nuestro conocimiento de los procesos permanentes e intermitentes alrededor de Iberia y evaluar su verdadero efecto en la evolución sedimentaria delos márgenes continentales que le rodean

A multiple Contourite Depositional System has been defined in the Plio-Quaternary sedimentary register in the Alboran Sea. This multiple system formed by the Atlantic and the low density and high density Mediterranean Waters, which shaped the margins and basins since the opening of the Gibraltar Strait. Three different (paleo)circulation scenarios are proposed since then: the Atlantic water Flooding;the Pliocene circulation, characterized by immature low and high density Mediterranean waters and a strong countercurrent in the Western Basin; and the Quaternary circulation, characterized by tabular Mediterranean water masses with multiple current dynamics,an increasing influence of density contrasts, and climate shifts causing major vertical and horizontal displacements of their interfaces.

The Quaternary stratigraphic architecture of seamounts and surrounding deposits in the eastern Alboran Sea reveals at least 53 stacked MTDs in the Pollux Bank, Sabinar Bank (Sabinar Platform and Western Sabinar), Maimonides Ridge, and Adra Ridge. These MTDs are grouped into two types based on their size: small-scale MTDs (length <5 km and thickness <18 ms) and large-scale MTDs (length >5 km and thickness >18 ms). The study of these deposits has allowed us to define a close relationship between size (thickness-length) and source area gradients. The frequency of MTD events has varied between 40 and 373 kyr throughout the Quaternary (1.8 Ma to present). Correlation between individual MTDs is difficult but could be done for at least one local MTD event between Sabinar Platform and Western Sabinar (Sabinar Bank); in addition, one regional MTD event has been recognized around all of the studied seamounts. These failure events could have been triggered by tectonically controlled seismicity at both regional and local scale.

The Portimao Bank is a structural high situated at the westernmost part of the Gulf of Cadiz continental margin, in the lower slope of the South Portuguese sector, between 3500 and 1200 m depth. This high has a W-E orientation and is bounded on the north by the D. Carlos valley and on the south by the Cadiz valley. This morphostructure has been related to a Variscan basement high strongly deformed by NW Africa-Eurasia convergence during Pliocene-Quaternary times and has been defined like a pop-up structure controlled by reverse faults both northwards and southwards with Pliocene-Quaternary activity. From a structural point of view, this bank exhibits a clear differentiation between western and eastern sectors. The main objective of this work is to contribute to the knowledge of the Pliocene-Quaternary and actual tectonic evolution of the Portimao Bank. This has been possible by the interpretation of the high resolution singled airguns and parametric profiles obtained in the MONTERA 0412 cruise, and two previous MCS profiles acquired in the TASYO 2000 cruise. Bank morphology shows a southern flank steeper and more gravity eroded than in the northern one, where also intense erosion is observed related to the D. Carlos valley. The summit shows a ramp-like morphology down westwards. However, this morphology is broken by the presence of the D. Carlos diapir in the center part of this bank, which marks also the boundary between western and eastern structural styles. In the eastern sector a basement high has been observed southwards which is interpreted as a reactivated reverse fault, which uplifted Pliocene-Quaternary units that thinning on the top. Northwards a longitudinal ridge is delimited at seafloor surface in relation to an anticline fold which is caused by a blind thrusts. In this sector the Pliocene-Quaternary uplift of the Portimao Bank is controlled by blind thrusts bounding the north and south. Their central part corresponds to an uplifted basin with syncline

Critical reviews of the available seismic records and analyses of CTD data in the Alboran Sea have changed the previous interpretations about the types of deposits making up the nearsurface sediments of the Alboran Sea. During the last 20 years many studies about sedimentation in the Alboran Sea suggested that turbiditic fans, gravitative deposits and hemipelagites characterized the slopes and sub-basins of the Alboran Sea. The new results suggest the dominance of contourites interrupted by submarine fans and sedimentary instabilities in those physiographic domains

Several attempts for establishing a good Plio-Quaternary stratigraphy were proposed and disputed since the beginning of the studies in the Alboran Sea during the 80’s. Now, we have reviewed all the available data with the purpose of improving the detail of the previous stratigraphy by adding new chronostratigraphic boundaries (Lower Pliocene Revolution –LPR-, Base Quaternary Discontinuity –BQD- and Middle Pleistocene Revolution –MPR-) with paleoclimatic and paleoceanographic significances. Their addition have allowed tracking the effects of the Mediterranean water masses on the sedimentation since the opening the Strait of Gibraltar. The new results indicate that the Pliocene and Quaternary sedimentary record is mainly characterized by contourites, comprising both depositional and erosive features, that contribute to the outbuilding of the margins and infilling of the basins. Thus, a new Plio-Quaternary sedimentary evolution model with dominance of the alongslope processes has been established for the Alboran Sea., Desde el inicio de la investigación científica en el Mar de Alborán en los años 80 se han presentado varios trabajos de estratigrafía Plio-Cuaternaria. Recientemente hemos revisado todos los datos disponibles con el propósito de mejorar el nivel de detalle de la estratigrafía previa, añadiendo nuevos límites cronoestratigráficos (Lower Pliocene Revolution –LPR-, Base Quaternary Discontinuity –BQD- y Middle Pleistocene Revolution –MPR-) con significados paleoclimático y paleoceanográfico. Su inclusión nos ha permitido rastrear los efectos de las masas de agua mediterráneas sobre la sedimentación desde la apertura del Estrecho de Gibraltar. Los nuevos resultados indican que el registro sedimentario Plio-Cuaternario está principalmente caracterizado por contornitas, que comprenden tanto rasgos deposicionales como erosivos, que contribuyen a la construcción de los márgenes y relleno de las cuencas. Esto ha permitido establecer un nuevo modelo de evolución sedimentaria durante el Plio-Cuaternario con dominancia de los procesos longitudinales para el Mar de Alborán.

Este trabajo presenta la caracterización morfo-sísmicas de depósitos de movimientos en masa que se desarrollaron durante el Cuaternario en el margen de Almería y en la Cuenca Oriental de Alborán en base a datos batimétricos y sísmicos de alta y muy alta resolución. Los depósitos de movimientos en masa están localizados en dos ambientes sedimentarios, talud abierto y altos morfológicos. Las áreas afectadas por estos depósitos varían entre 10 km2 y 255 km2. Asimismo, se propone una clasificación de los movimientos en masa para estos márgenes en base a una serie de criterios que incluyen el mecanismo causante, la localización del área fuente y la localización fisiográfica y que estaría constituida por tres tipos de sistemas de inestabilidad sedimentaria: i) adosados a plataforma, ii) adosados a talud, iii) localmente no adosados., This paper presents the morpho-seismic characterization of Quaternary mass-movement in the Almeria margin and eastern Alboran Basin on the basis of the bathymetric and high and very highresolution seismic data. The mass-movement deposits are located in two sedimentary environments, open slope and morphological highs. The area affected by these deposits varies between 10 km2 and 255 km2. A classification of these mass movements deposits, based on a series of criteria including the causative mechanism, the source area location and physiographic location, is here proposed, differentiating three types of systems: i) attached to platform, ii) attached to slope and iii) detached locally.

Este trabajo analiza la arquitectura estratigráfica del abanico distal de Almería del Pleistoceno Superior en base a datos batimétricos y sísmicos de alta y muy alta resolución. Se establecen dos unidades sísmicas, U2 y U1, que alcanzan respectivamente un espesor máximo de 200 ms y 136 ms. Están constituidas fundamentalmente por un total de seis lóbulos de abanicos que de base a techo son del 1 al 6 con intercalaciones de depósitos de movimiento de masa. En base a las dimensiones geométricas de estos lóbulos de abanico así como de su arquitectura se establecen dos importante fases evolutivas. La fase 1 (0.900-0.440 ma.) es de tipo agradante y en ella tiene lugar el confinamiento de los lóbulos de abanico 6 al 4 que presentan una morfología elongada y con dimensiones geométricas similares. La fase 2 (0.440 ma.-presente) es de tipo retrogradante y durante su desarrollo no están confinados los tres lóbulos de abanico (3 al 1), que presentan formas lobuladas y elongadas y así como una disminución de sus dimensiones geométricas., This paper focus on a seismic-stratigraphic and architecture analysis of the Almeria fan based on bathymetric data and high and very high resolution seismic data. Two seismic units are defined above the reflector MPR (0.900-0.920 ma) and they consist mainly by six fanlobes and interbedded mass movement deposits. The Pleistocene sedimentary evolution could be explained by two phases. Phase 1 (0900-0440 m.) is aggrading type during which confinement of three fanlobes (6-4) occurred. They present an elongated morphology and similar geometric dimensions. Phase 2 (0.440 ma-present) is a retrograding type during which three fanlobes (3-1) showing lobe/elongate forms and decreased on their geometric dimensions.