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Workshop. Alboran Domain and Gibraltar Arc: Geological Research and Natural Hazards - El dominio de Alborán y el Arco de Gibraltar: Investigación geológica y riesgos naturales - Le Domaine Alboran et l'Arch de Gibraltar: Recherche géologique et risques naturels, 16-18 octubre 2019, Granada..-- 2 pages, 1 figure, The distal Almeria Turbidite System (ATS) is located in an active tectonic and partially-confined setting along the Spanish Mediterranean continental margin (NE Alboran Sea). The architectural elements are leveed-channel, distributary channels and several distributary channels and distal fringes forming a lobe system. In this work the lobe system has been studied with very high-resolution analysis integrating multibeam bathymetry, near-surface sub-bottom parametric seismic, and ODP-977A core data (depth, age, oxygen isotopes, and Marine Isotope Stages MIS). It allows us to establish the stratigraphy and give new clues to better understanding the sedimentary evolution of the most recent lobe system deposited over the last 575 kyr. The seismic stratigraphy analysis reveals two seismic units, U1and U2, from older to younger, and three sub-units (U1a to U1c, and U2a to U2c) in each seismic units that are bounded by six seismic boundaries (the oldest being R1 and the youngest R6) over the last 575 kyr (Fig. 1). The detailed seismo-facies analysis of the unit U2 allow the identification of three depositional bodies: channelized lobes, mass-transport deposits and hemipelagites. The lateral and vertical distributions of these deposits suggest change in deposition stacking pattern for the last 269 kyr. A stacking pattern of compensation occurred from 269 kyr to 70 kyr, with a general eastern migrating trend, in which the deposition of lobes within the U2 is controlled by the lows created by ancient lobes developed within U1 and sediment supply along the whole ATS. From 70 kyr to present, the system evolves from aggradational to retrogradational stacking pattern. The new approach of seismic chronostratigraphic correlations, coupled with Marine Isotope Stages (MIS), suggest the development of the lobe complex mostly conditioned by glacio-eustatic sea-level cycles of 200 and 100 kyr and associated sediment supply. During sea-level falls in lowstand stages (glacial MIS 8, 6 and 4), take place an increase of submarine canyon activity and mass-movements whereas during sealevel rises in highstand stages (interglacial 7 and 5) much of the terrigenous sediment remained trapped on the shelf or proximal reaches of the Almeria Canyon, leaving the distal Almeria Turbidite System dominated by hemipelagic settling. The lobe system can be defined as attached one taking into in consideration that the depositional architecture of the Almeria lobes begins at the mouth of the main leveed channel, in the absence of the channel lobe transition zone found in other turbidite system. The architecture with a great variety of seismofacies, and the plan-view morphology of the lobes elements would indicate that this system roughly matches of mixed sand-mud composition turbidite systems. Finally, this work provides new insights to calibrate deepwater facies models in complex tectonic and partially confined settings and it represents important modern analogue data to improve deep subsurface reservoir models for the oil and gas industry

Workshop. Alboran Domain and Gibraltar Arc: Geological Research and Natural Hazards - El dominio de Alborán y el Arco de Gibraltar: Investigación geológica y riesgos naturales - Le Domaine Alboran et l'Arch de Gibraltar: Recherche géologique et risques naturels, 16-18 octubre 2019, Granada..-- 2 pages, 1 figure, The NW Alboran Sea contains geological evidences of the intricate interplay of downslope and alongslope features on one hand, and of the interaction of the Atlantic Waters flowing out and the intermediate Mediterranean Waters (MWs) flowing into the Strait of Gibraltar on the other hand.Both of these interactions are of high scientific relevance and have been studied separately before, but must also be considered together since both phenomena occur simultaneously. The work is based on data acquired during the FAUCES surveys, comprising high-resolution bathymetry and seismic profiles, in combination with a database comprising seismic profiles acquired since the 70s. The interaction between downslope and alongslope processes occurs on both margins of the Alboran Sea, but this interaction is especially complex in the Spanish margin, where the turbidite canyons cut the continuity of terraced plastered drifts. The interaction may vary between the dominance of downslope processes over the alongslope processes (i.e., Almeria turbidite system), the alternation between downslope and alongslope deposits (which is the case of the most recent lobe of the Guadiaro fan) and the influence of alongslope processes over downslope processes. The Guadiaro canyon provides an example of the last case: After a first phase in which the canyon was incised, during a second phase (Pliocene) downslope processes were dominant, as indicated by the chaotic facies infilling the canyon incision. A last phase (Quaternary) characterized by stratified discontinuous facies indicate a greater influence of contourite alongslope deposits. During the stage two and mostly during stage three, the lateral accretion of packages (LAPs) of stratified facies with NE progradation trend have been recognized on its SW side (right margin), progressively invading of the Guadiaro Palaeocanyon and affecting its current location and shape (Fig. 1). These findings have been confirmed by isochore maps, in which a depocentre of Quaternary age runs parallel to the canyon on its SW side. The oceanography of the study area is marked by the closeness to the Strait of Gibraltar, located to the west. The Mediterranean intermediate waters, comprising Western Intermediate Waters (WIW), Levantine Intermediate Waters (LIW) and the upper portion of Tyrrhenian Dense Waters (TDWi), flow along the Spanish margin towards the Strait. On the opposite, the Atlantic Waters enter forming a strong jet into the Mediterranean. These two groups of water masses are separated by a pycnocline, along which internal waves formed in the Camarinal Sill travel eastwards. The NE progradation of the LAPs affecting the Guadiaro canyon points to the much stronger effect of the Atlantic Jet and the eastwardtravelling internal waves over the intermediate MWs directed towards the Strait of Gibraltar. Ultimately, these findings may shed light on one of the reasons behind the sudden abandonment and obliteration of the Estepona Palaeocanyon after the BQD, possibly located where the Atlantic Jet and the internal waves cease their sediment transport towards the NE and where the weaker SW transport by the intermediate Mediterranean Waters become the only alongslope transport mechanism, Contribution from Project FAUCES - CTM2015-65461-C2-R (MINECO/FEDER)

Workshop. Alboran Domain and Gibraltar Arc: Geological Research and Natural Hazards - El dominio de Alborán y el Arco de Gibraltar: Investigación geológica y riesgos naturales - Le Domaine Alboran et l'Arch de Gibraltar: Recherche géologique et risques naturels, 16-18 octubre 2019, Granada..-- 2 pages, 1 figure, 1 table, La presencia de cabeceras de cañón submarino cerca de la línea de costa en los márgenes continentales del sur de la Península Ibérica representa una amenaza potencial, debido tanto a sus posiciones poco profundas como a sus configuraciones morfosedimentarias activas. El cañón Almanzora-Alías-Garrucha, ubicado en el margen continental de Palomares (SO de Iberia), es un sistema de cañones profundamente incidido en la plataforma continental. El cañón tiene una longitud total de 74 km y se extiende desde la costa hasta -2500 m. La cabecera y el curso superior del cañón están constituidos por varios tributarios como los cañones Almanzora, Garrucha, Cabrera y Alías de N a S. Todos ellos convergen a los -1820 m, resultando un cañón único de 46 km orientado O-E. La mayoría de los afluentes muestran una indentación progresiva y sus partes más someras llegan costa alcanzar el infralitoral representando un peligro potencial para el puerto de Garrucha. La combinación de batimetría de alta resolución, perfiles sísmicos, testigos de sedimento y medidas geotécnicas (laboratorio e in-situ-CPTu) ha permitido caracterizar la fisiografía, geomorfología y los procesos sedimentarios asociados a los diferentes dominios del cañón, incluidos sus márgenes. Las características erosivas y de inestabilidad sedimentaria tienen una amplia distribución en toda el área y pueden observarse como características de primer (cicatrices y depósitos de transporte en masa), o segundo orden (cicatrices menores, escarpes, bloques aislados). Además, todas las morfologías observadas en la cabecera y el curso superior del cañón están relacionadas con los procesos erosivos asociados a la evolución del cañón, por ejemplo redes de cárcavas dendríticas y cicatrices que afectan a los flancos del cañón. El riesgo asociado a la evolución de la cabecera del cañón de Garrucha sobre el puerto de Garrucha se ha evaluado mediante la caracterización geotécnica del área (incluyendo ensayos CPTu) y realizando análisis de estabilidad para calcular el Factor de Seguridad (FS) en aquellos perfiles batimétricos más representativos del área. En las zonas cercanas al puerto, se han definido 3 unidades geotécnicas (GU1-3; Tabla 1). La GU1, próxima al puerto, está compuesta por sedimento granular (arenas limosas densas), no plástico, de nula cohesión y poco compresibles. En caso de deslizarse y aunque fuesen eventos superficiales, éstos afectarían a la estructura del puerto. La GU2 es otra unidad granular poco compresible, de grano fino y sin plasticidad. Se distribuye a lo largo de las zonas más someras de los flancos internos del cañón y podría ser interpretada como sedimentos retrabajados de origen gravitacional. La GU3 distribuida en zonas más alejadas del puerto, en la plataforma continental, está caracterizada por sedimento limoso y cohesivo, de baja plasticidad y muy compresible. En caso de desestabilizarse esta unidad movilizaría un mayor volumen de sedimento que la GU1 aunque tendría un menor impacto directo sobre el puerto. El factor de seguridad en condiciones estáticas muestra que el único valor cercano a la inestabilidad se localiza en las áreas dominadas por la unidad GU3, mientras que ante la presencia de una carga sísmica las condiciones de no equilibrio se imponen en toda la zona

Workshop. Alboran Domain and Gibraltar Arc: Geological Research and Natural Hazards - El dominio de Alborán y el Arco de Gibraltar: Investigación geológica y riesgos naturales - Le Domaine Alboran et l'Arch de Gibraltar: Recherche géologique et risques naturels, 16-18 octubre 2019, Granada..-- 2 pages, La zone d’Alboran constitue un laboratoire d’exception pour l’étude in situ de la réactivation des bassins localisés à la frontière de plaques. Le bassin d’Alboran s’est formé lors d’un épisode extensif Oligo-Miocène contrôlé par le retrait du panneau plongeant Ouest Méditerranéen, puis a subi une inversion tectonique depuis la fin du Miocène sous l’effet de la convergence Afrique-Europe. En mer d’Alboran, de nombreuses manifestations fonds de mer sont liées aux interactions entre des systèmes sédimentaires variés (sédimentation-érosion), les variations glacio-eustatiques et une structuration tectonique active. Les bancs de Xauen/Tofiño, de Francesc Pagès et la Ride d’Alboran, ainsi que les zones sismiquement actives comme la zone de faille d’Al Idrissi et la Baie d’Al Hoceima au large du Maroc, ont été sélectionnés comme zones d’étude car elles ont enregistré l’ensemble des déformations du bassin Sud d’Alboran depuis plus de 8 millions d’années. La taille modeste de ce bassin et ses connexions avec l’océan mondial réduites depuis 6 millions d’années permettent de mieux contraindre les processus en action lors de l’interaction entre les courants de contour de méditerranée, les systèmes gravitaires au sens large et les hauts structuraux en formation depuis le Tortonien-Messinien. L’objectif de ce projet est d’acquérir des données de carottage en mer d’Alboran sur différents systèmes sédimentaires, et zones de tectoniques actives afin de réaliser une étude intégrée des interactions entre les systèmes sédimentaires, l’activité tectonique pliocènequaternaire et les variations du niveau marin. L’activité des failles et des plis de croissance ont un contrôle sur les circulations des masses d’eau enregistrées par les dépôts de contourites. Les variations du niveau de la mer contrôlent les interfaces entre ces masses d’eau. L’ensemble des processus de dépôts (contourites, turbidites, MTD) et d’érosions (terrasses marines) enregistrent les interactions entre processus sédimentaires et tectonique active. La campagne océanographique Albacore, qui aura lieu sur le navire océanographique le Marion Dufresne en 2020, se focalise sur cinq objectifs principaux : - Objectif 1 : comprendre le modèle morpho-structural actuel de la partie sud de la mer d'Alboran, dater les pulses tectoniques et les systèmes sédimentaires associés, et préciser la source et la nature du banc Xauen-Tofiño. - Objectif 2 : déterminer le profil stratigraphique des contourites de la mer d'Alboran et du plateau continental marocain du Pléistocène tardif à l’Holocène et leurs implications paleoocéanographiques : modèles et rocessus. - Objectif 3 : explorer l'évolution chronologique des monts de coraux d’eaux profondes (DWC) et leur signature paléo-océanographique et paléoclimatique depuis le Pléistocène supérieur. Objectif 4 : étudier les facteurs déclenchants et favorisants les instabilités de pentes et évaluer le risque géologique associé aux pulses tectoniques agissant dans la partie sud de la mer d'Alboran. - Objectif 5 : déterminer la stratigraphie séquentielle récente de haute résolution du plateau continental d'Al-Hoceima afin d’analyser les changements du niveau de la mer au Pléistocène tardif et à l'Holocène, qui varient de l'échelle millénaire, centenaire à multi-décennale, et afin de mieux comprendre les processus contrôlant la variabilité de la sédimentation sur le plateau. Les carottages Calypso, Casq, gravité, prélèvement CNexo-Ville, mesures in situ géotechniques avec le Penfeld, et dragages nous permettront de déterminer la nature, de dater et ainsi calibrer des marqueurs clés, de déterminer les taux de sédimentation ainsi que les caractéristiques mécaniques des sédiments dans la zone d’étude. L’objectif général étant de contraindre l’évolution paléo-océanographique de la Mer d’Alboran depuis le Pliocène, de quantifier les mouvements verticaux de la marge sud, d’obtenir un meilleur contrôle chronostratigraphique des structures actives et une caractérisation mécanique de la couverture sédimentaire permettant l’analyse de la stabilité des pentes actuelles. A terme une meilleure compréhension des aléas naturels (tremblements de terre, glissements de terrain et tsunamis) constitue un des objectifs de ce projet

Workshop. Alboran Domain and Gibraltar Arc: Geological Research and Natural Hazards - El dominio de Alborán y el Arco de Gibraltar: Investigación geológica y riesgos naturales - Le Domaine Alboran et l'Arch de Gibraltar: Recherche géologique et risques naturels, 16-18 octubre 2019, Granada..-- 2 pages, El talud superior de Cádiz se sitúa en las cercanías del Estrecho de Gibraltar (latitud 36º10’N-36º40’N), desde el borde de la plataforma, en torno a 120 m de profundidad, hasta la conexión con el talud medio a 400-500 m. Mediante el análisis de perfiles de sísmica de reflexión de diferentes resoluciones y de mapas batimétricos del talud, este trabajo explora la relación entre procesos estructurales profundos, principalmente diapiros y altos estructurales relacionados con la actividad de la Unidad Alóctona del Golfo de Cádiz, con los procesos sedimentarios deposicionales y erosivos derivados del flujo de las masas de agua y los procesos gravitacionales en el talud superior. El registro sedimentario reciente desde el Pleistoceno medio hasta la actualidad en el talud de Cádiz se divide en dos unidades sísmicas, correlacionadas con el marco estratigráfico regional (Hernández-Molina et al., 2016). Ambas unidades definen la construcción de un depósito contornítico adosado al talud superior (Hernández-Molina et al., 2013) y su continuación como depósito laminar en el talud medio. Sin embargo, muestran diferencias significativas en cuanto a su distribución y sus características sísmicas. También se identifican variaciones importantes en su configuración interna, entre la parte SE de la zona de estudio, donde el talud superior conecta con el canal contornítico de Cádiz, y la parte NW donde conecta con depósitos laminares del talud medio. La unidad inferior (Pleistoceno medio-Cuaternario inferior) está deformada por la actividad de numerosos diapiros, en particular en la zona SE, según revela la inclinación y acuñamiento de los reflectores hacia los edificios diapíricos. Sus principales depocentros se distribuyen en las zonas deprimidas entre altos diapíricos, y su configuración interna incluye reflectores estratificados paralelos en la zona NW y ondulados en la zona SE. Por el contrario, la unidad superior (Cuaternario inferior- presente) se distribuye de forma más homogénea en el talud superior actual, mostrando deformación por efecto de diapiros sólo en la parte NW del área de estudio, que afecta hasta el registro más superficial. En esta unidad se desarrollan los principales rasgos morfo-estratigráficos que definen la configuración actual del margen: progradación del talud, canales contorníticos relacionados con las dorsales diapíricas, y valles submarinos de origen gravitacional que muestran mayores profundidades de incisión en la parte SE del área de estudio. La configuración interna de la unidad superior muestra reflectores ondulados en el talud superior de toda la zona de estudio. La interpretación preliminar de estos datos indica que la construcción del talud de Cádiz desde el Pleistoceno medio ha estado fundamentalmente controlada por una compleja interacción entre los procesos tectónicos recientes relacionados con la actividad de los diapiros fósiles o aflorantes y la dinámica de las masas de agua y sus interfases. La variabilidad del registro sísmico y morfológico entre las zonas SE y NW del área de estudio sugiere una progresiva migración de la actividad diapírica hacia el NW, donde controla los procesos sedimentarios recientes. En cambio, en la zona SE la sedimentación reciente está más dominada por los procesos oceanográficos, y por su interacción con procesos gravitacionales, Esta investigación ha sido financiada por los proyectos Talus (CGL2015-74216-JIN), Inpulse (CTM2016-75129-C3-1-R), Graco (Eurofleets2), Mower (CTM2012-39599-C03-02) y Contouriber (CTM2008-06399-04-04)

34th International Association of Sedimentologists (IAS) Meeting of Sedimentology, Sedimentology to face societal challenges on risk, resources and record of the past, 10-13 September 2019, Rome.-- 1 page, The Almanzora-Alías-Garrucha canyon system is located in the Palomares continental margin (SW Mediterranean Sea). The canyon head is constituted by several tributaries such as Almanzora, Garrucha, Cabrera and Alías canyons from N to S. The Garrucha canyon is deeply incised in a narrow continental shelf (less than 5 km wide). Its head is very complex with a dense network of gullies and tributaries that reach almost the shore at 7-20 meters water depth (mwd). In contrast, the Almanzora canyon is less incised and its head is located at 65-90 mwd on the outer prodelta of the Almanzora river. The aim of this work is to study the interaction processes of the Almanzora prodelta with the canyon head, in particular with the Almanzora and some tributaries of Garrucha canyon. For this goal, high resolution multibeam bathymetry adquired in the ESPACE project and surface sediments, recently obtained in the framework of FAUCES project, have been used.The Almanzora prodelta is 3500 m wide and 4000 m long with E-NE direction. The morphological analysis shows different scale bedforms that develop an undulation field which affect almost the whole área of the prodelta. A dense network of radial erosive channels (up to 140 m wide) can be also observed with some of them clearly connected with the gullies that feed the canyon heads of Almanzora and Garrucha tributaries. Associated to these channels and gullies there are several pockmarks on the westernmost distal part of the prodelta. Grain-size analysis of samples distributed along and across the prodelta and the upper courses of gullies shows that sediment texture ranges from silty sand to sandy silt and silt, with less than 11% of clay. Visual analysis of the coarser fraction of sediment evidenced the presence of quartz and micas with heavy minerals (e.g. goethite, hematite) and a variable percentage of bioclasts. Principal Component Analysis determined two main factors that explain the 97% of the total variance and allow establishing 3 textural groups. F1 (84%) let to split the samples in two main groups, i.e. sand and fine-grained dominated, and F2 (13%) that shows the influence of depth on fine sediments with increasing clay content. The first textural group includes sandy sediments of the undulation field in the prodeltaic deposit. The second group is composed by silty sediment observed in the distal boundary of the prodelta and adjacent zones, including gullies and pockmarks. The finest sediments (third group) are in the head of Almanzora and some tributaries of Garrucha canyon that also correspond to the deepest samples (± 270 mwd). The spatial distribution of these deposits is interpreted as the result of the main influence of flows crossing the prodeltaic deposit related to hyperpycnal flows favored during periods of high river discharge and triggered by torrential precipitations. The coarser sediments are mainly deposited in the prodeltaic lobe favoring its development, while fine-grained sediments are transported through the erosive channels and gullies to canyon head, feeding the canyon system, Contribution from Project FAUCES CTM2015-65461-C2-R (MINECO/FEDER)

34th International Association of Sedimentologists (IAS) Meeting of Sedimentology, Sedimentology to face societal challenges on risk, resources and record of the past, 10-13 September 2019, Rome.-- 1 page, The Algeciras Canyon is located in the axis of the horseshoe-shaped Algeciras Bay (SW Mediterranean Sea, NE Strait of Gibraltar) and can be considered a potential geohazard source due to its proximity to the coast. Full-covered multibeam bathymetry and highresolution parametric seismic profiles have allowed us to characterise the geomorphology and morphosedimentary dynamics of this canyon. The canyon varies in width from 1.2 to 3.6 km and reaches a length of 19 km along a winding but mainly NNW-SSE course, with a sinuosity index of 1.15 and relief features (margins¿thalweg) ranging from 90 to 560 m. There are larger NNW-SSE to N-S oriented segments along its course, conditioned by faults, and shorter sections controlled by WNW-ESE trending structures. The canyon head is 0.7 to 0.9 km offshore, at 60-80 m below sea level (mbsl) and its mouth outflows in the northeastern part of the Strait of Gibraltar, at 890 mbsl.Morphologically characterising the Algeciras Canyon (thalweg and walls) has allowed us to define three sectors: headwall, middle course, and distal part. These sectors reflect different sedimentary dynamics through the canyon, where alongslope and downslope processes interact. (1) The headwall (60-390 mbsl) is characterised by a sharp rim, located at 60-80 mbsl, which is shallower and sharper in the western margin. This sector also presents an asymmetric transverse profile, with the thalweg located close to the western margin and a slightly and wider eastern margin. Erosive processes are dominant in the upper segment and western margin, while the eastern margin is affected by bottom current dynamics that rework and redistribute the sediments, creating a sedimentary deposit, between 140 and 300 mbsl, characterised by small mounded and separated drifts. Its architecture comprises aggradational layered deposits separated by erosive surfaces. (2) The middle sector (390-550 mbsl) is marked by a meandering pathway, gullied walls, rocky outcrops, a structural bend in the southern part, and minor sedimentary patches on the western margin. This sector is dominated by downslope and alongslope processes. Gully incisions increase towards the down-canyon on both flanks, particularly the eastern one, which seems to control the down-canyon reactivation of sedimentary processes in the main channel. Also, minor patches of plastered drifts occur in different locations on the western flank. In (3) the distal sector (550-890 mbsl), downslope confined gravitational processes dominate. These are related to the dynamics of the eastern margin gullies described in the middle sector, where their mouths follow the direction of the main channel course of the canyon. Several crescent bedforms spreading along the thalweg also indicate sediment reworking down-canyon. The inflow and outflow dynamics of the Atlantic Jet and Mediterranean Outflow Water masses through the canyon produce alternating deposition and erosion in different segments of the canyon as a consequence of its irregular morphology. These dynamics also influence the occurrence of gravitational processes in the headwall segment and along several gullies, This is a contribution from RIGEL (IEO, Spain) and FAUCES (CTM2015-65461-C2-R, MINECO/FEDER) Projects

34th International Association of Sedimentologists (IAS) Meeting of Sedimentology, Sedimentology to face societal challenges on risk, resources and record of the past, 10-13 September 2019, Rome.-- 1 page, The occurrence of extensive Plio-Quaternary contourite drifts in the Alboran region has recently been well documented, principally using geophysical methods. However, the sedimentological characteristics are not yet well documented, in spite of the fact that they provide a record of palaeoceanographic/climate changes. In this study, the sedimentary and geochemical characteristics of the contourite drifts formed by the Western Mediterranean Deep Water (WMDW) are examined in a core transect represented by three cores at 631 m, 712 m, and 914 m water depth. Three facies (1 to 3) are defined based on a combination of sedimentological and Zr/Al ratio. Facies 1 is the most dominant and consists of silty-clay, representing the finest-grained sediments; Facies 2 is composed of bioturbated clayey-silt with a remarkable Zr/Al peak, deposited during the Younger Dryas; Facies 3 consists of the coarsest sediments (sand), deposited during Heinrich event 2. The latter two facies present a remarkable Zr/Al peak. The mainly fine-grained contourites allow the Alboran contourite drifts to be classified as ¿muddy contourites¿. The vertical succession of these three facies permits the definition of two bi-gradational sequence types. Sequence A, represented by the vertical succession of facies 1, 2, 3, 2, 1, corresponds to the standard contourite sequence model, while Sequence B is composed of a vertical succession of facies 1, 2, 1, and corresponds to partial contourite sequences. Both sequences, A and B, are linked to shifts in the strength of the bottom currents, from weak to strong and then back to weak, corresponding to acceleration/deceleration periods. To decode the contourite facies successions in terms of bottom current speed, a comparison between two binary plots has been made: magnitude changes in mean sortable silt (meanss in µm) and changes in WMDW flow speed (in cm/s) versus four periods of acceleration of bottom currents (a: 23.4- 19 ka, b: 17.8-16.2 ka; c:15.0-12.5 ka; d: 9.8-8.0 ka). The regional Alboran palaeo-WMDW flow speed has been assessed using a similar record (meanss) from another contourite drift in the NW Mediterranean at 2391 m wd, close to the formation zone of the water mass. This comparison reveals that the Alboran contourite drifts were affected by low (~1.5-5.5 cm/s) and moderate flow speeds (~8-13 cm/s). These palaeo-speeds are in the same range as modern oceanographic data, indicating that the WMDW flow operated on the construction of those drifts in two hydrodynamic scenarios: Scenario 1 corresponded to low bottom current speeds (< 5.5 cm/s) for the period b; Scenario 2 was defined by higher bottom current speeds (up to ~12.8 cm/s), during the periods a, c, and d. This research represents a prime example of bottom current effect on the construction of contourite drifts and how to apply fine-grained, mainly muddy contourites in sedimentological and palaeoceanographic studies, despite the strong bioturbation. The core transect provides a regional perspective of bottom current flow, from close to its formation area along its pathway, which is governed by topographic restrictions (e.g., seamounts and submarine canyons), Contribution from Project FAUCES CTM2015-65461-C2-R (MINECO/FEDER)

34th International Association of Sedimentologists (IAS) Meeting of Sedimentology, Sedimentology to face societal challenges on risk, resources and record of the past, 10-13 September 2019, Rome.-- 1 page, Submarine canyons are deep incisions acting as sediment pathways that connect shallow continental shelves to deep basins. The sediment from shallow waters can mix with seawater to form downslope running submarine density flows that are extremely powerful. These flows carry crucial nutrients to submarine life, control the hydrocarbon reservoir distribution, and mobilise the seabed sediment to form erosional and depositional features such as bedforms. Previous works have suggested links among the characteristics of the bedforms (e.g. size, shape, grain- size), density flow dynamics and submarine canyon architecture. Recent progress in monitoring technology has allowed a better understanding those links but field measurement are key to correlating that complex interplay. Here we show field measurements collected in the Garrucha Canyon (SW Mediterranean Sea) within the framework of FAUCES project. The measurements comprise: 1) high-resolution bathymetry data acquired by an autonomous underwater vehicle to characterise the submarine canyon; 2) video images recorded by a remote operated vehicle (ROV) of erosional and depositional features; and 3) grain size analysis of 5 micro-cores collected in each ROV dive at different settings within the canyon. The high-resolution bathymetry data show that crescentic-shaped bedforms are common in a section of the canyon floor at 1,500-2,000 m of water depth. The wavelength and wave height of those bedforms spreads from 15 to 120 m and from 1 to 10 m respectively. These bedforms suggest that the floor of the Garrucha Canyon is active. Previous observations in other submarine canyons of similar crescentic-shaped bedforms have been suggested to be related to the transition between supercritical and subcritical flows, and interpreted as cyclic steps. A further analysis of the video images and grain size of the micro-cores might point out the sedimentary process that controls the bedforms of the Garrucha Canyon. The outcome of this work highlights the difficulties to identify a particular bedform as the unique signature of submarine canyon dynamics. It will also provide additional results to achieve an enhanced knowledge of the sedimentary processes within submarine canyon and have potential implications to identify spatial geohazards and benthic ecosystem niches in these submarine environments, Contribution from Project FAUCES CTM2015-65461-C2-R (MINECO/FEDER), Spain

34th International Association of Sedimentologists (IAS) Meeting of Sedimentology, Sedimentology to face societal challenges on risk, resources and record of the past, 10-13 September 2019, Rome.-- 1 page, The Alboran Sea is a key location to understand the geologic evolution of the Strait of Gibraltar and also to understand the influence of straits in sedimentation of adjacent areas. Since the Upper Messinian, the Strait of Gibraltar has conditioned sedimentation in the Western Alboran Sea (WAB). This work brings together the results of several works during the last few years. These results allow us to define three major sedimentary phases closely related to the geological evolution of the Strait of Gibraltar and its influence in the circulation of the Atlantic and Mediterranean waters: I) erosion, II) downslope and alongslope sedimentation; and III) predominance of alongslope sedimentation with erosive and depositional processes.The erosive phase (I) occurred during the Messinian Salinity Crisis when the Strait was closed, and during the Zanclean Atlantic flooding when the Strait was opened. Both periods provoked a great erosion on the margins and deep-sea areas of the WAB. The erosive surface displays different types of features, being the most striking the canyons, which are interpreted as formed in subaerial conditions and represent the >mother> submarine valleys of most of the present-day canyons, and also a large longitudinal channel that evolves from the Strait of Gibraltar corridor. The second phase (II) began just after the Atlantic flooding, when the circulation of the Mediterranean waters restored, and spaned until the end of the Pliocene. Sedimentation was characterized by the interplay of downslope gravitational processes that affected to the subaerial valleys when they were submerged. These processes contributed to form turbidite systems mostly in the northern margin. Contrasting, most of the subaerial canyons of the southern margin were obliterated by an alongslope sedimentation that allowed the formation of contourite drifts. The local topography of the Strait of the Gibraltar and WAB controlled the pattern currents, mainly of the proto-Mediterranean deep waters. This water mass seemed to be affected by a relatively important recirculation in the WAB before it outflowed through the Strait of Gibraltar to the Atlantic Sea. The third phase (III) is mainly dominated by the Atlantic and the Mediterranean alongslope processes and spans during the Quaternary until the present-day. Their action contributes to erode the upper continental slope and to deposit on the lower slope and adjacent deep sea area. Likewise, the erosive character seems to increases toward the Strait of Gibraltar, due to an acceleration of the Mediterranean waters in that direction and the high energy of the incoming Atlantic Water

34th International Association of Sedimentologists (IAS) Meeting of Sedimentology, Sedimentology to face societal challenges on risk, resources and record of the past, 10-13 September 2019, Rome.-- 1 page, The occurrence of extensive contouritic deposits along the Alboran Sea (SW Mediterranean Sea) is well known and described. Sedimentary instability linked with contouritic depositional systems has been observed around the world. Erosive processes associated to bottom currents may, in fact, cause undermining slopes and instability but contouritic sediments may be also prone to failure because of their composition (i.e., well-sorted) and geometry. They often develop excess pore pressure due to high sedimentation rates and/or relatively high organic-carbon content. The aim of this work is to study the morphological, sedimentary and geotechnical characteristics of a contouritic drift located on the Spanish margin of the Alboran Sea, between the Guadiaro and Baños submarine canyons. Geotechnical and sedimentological properties have been determined along two profiles across the contouritic drift, where 14 in situ geotechnical tests (CPTU) and several gravity cores were recovered in the framework of Fauces project. Sedimentological and geotechnical tests, such as grain size analysis, Atterberg limits, oedometric, direct shear and triaxial have been carried out at different intervals of sediment cores.The drift is shaped by a contouritic terrace mostly formed by sediments that contain poorly and very poorly sorted coarse medium sand (2.6 Ø medium size). The sand fraction (74%) is mainly composed of relict bioclastic fragments (30%), mixed with glauconite grains (44%). In the rest of the drift, sediments can be defined as high plasticity silts that, in general, are fine-grained towards the distal parts of the drift (> 96% of silts and clays) and coarser towards the shallow parts (30-40% of silts and clays); the plasticity also increases towards the deepest areas (Plasticity index from 4 to 28). This zoning across the drift has also been observed in geotechnical properties. CPTU tests allowed to determine the undrained shear strength (Su), obtaining values up to 10-15 kPa in the distal areas of the drift, and very high values for the coarser sediments. On the other hand, the direct shear tests (CD) results provide, for the silty sediments, an effective cohesion between 3.8 and 7.4 kPa and an effective friction angle between 25° and 28°.The results of the geotechnical and sedimentological tests allowed to model the stability of the contouritic drift, adding in some cases a seismic acceleration characteristic of the area. Although no significant number of sedimentary instabilities has been observed and described along the drift, its geotechnical properties indicate that they could be triggered. The discrepancy can be explained by: 1) small seismic accelerations can favour the consolidation of surficial sediment and therefore the increase of its strength; 2) the cyclic loading pulses induced by the formation of solitons in the Strait of Gibraltar could also favoured strength increase; 3) the drift can be affected by small surficial landslides, that are under the resolution of bathymetry, which would produce a stable and slightly overconsolidated seafloor; and 4) the geometry of the drift, shaped by an upper contouritic terrace would makes the whole deposit more stable

XV Reunión Nacional Cuaternario, 1-5 July 2019, Bilbao.-- 4 pages, 4 figures, Se presenta un estudio sedimentológico y cronoestratigráfico de las contornitas del Mar de Alborán (Mediterráneo SO) en base al registro sedimentario de dos testigos de sedimento. En este estudio se incorporan marcadores físicos de corrientes de fondo (¿sortable silt mean grain size¿ meanss) y marcadores químicos de cambios ambientales (Si/Si+Al y Zr/Al ratios) con el objeto de decodificar las sucesiones de contorníticas en términos de variabilidad de velocidad de las corrientes de fondo en relación con cambios paleoambientales. Estos resultados son validados con la inclusión del registro del meanss de un testigo localizado en el Mediterráneo Nor-Occidental. Este transecto proporciona una perspectiva regional de los cambios de velocidades de la corriente profunda del Mediterráneo Occidental durante los últimos 24 ka B.P., This work was supported by the FAUCES Project (CTM2015-65461-C2-R; MINECO /FEDER)

European Geosciences Union (EGU) General Assembly, 7-12 April 2019, Vienna, Austria.-- 1 page, The FAUCES project addresses the study of marine geological hazards, with special emphasis on slope stability, associated with three submarine canyons located on the Mediterranean continental margins of southern Iberia. The working hypothesis of FAUCES project is that the Almanzora-Alías-Garrucha canyon head on the continental margin of Palomares, and the La Linea and Guadiaro canyon heads on the Alboran margin, represent a potential threat, because of their shallow locations and active morphosedimantary configurations. To achieve the project FAUCES a multi-disciplinary approach is running and integrates geological and geotechnical data of the three study areas through the acquisition of different data sets (acoustic, seismic, sedimentological, geotechnical and in-situ measurements). This data allowed to determine the geomorphology and geological evolution and to analyze the slope-stability of the canyon heads. During the recent oceanographic cruises performed, we described a great variety of features such as bedforms, mass-movement deposits (isolated blocks, slides, mass flow deposits and hummocky topographies/debris avalanche deposits), erosive surfaces, fluid dynamic features and contourites. The preliminary results point to canyons show different geomorphological activity and sediment transport, and their canyon heads unequally interact with coastal and fluvio-marine processes, the action of bottom currents, or seismicity related to tectonic features. Likewise, a closer examination of the morphology of the Garrucha canyonhead lead us to point that it represents a potential hazard for the Garrucha habour, located just above it, where numerous erosive features are being been mapped

34th International Association of Sedimentologists (IAS) Meeting of Sedimentology, Sedimentology to face societal challenges on risk, resources and record of the past, 10-13 September 2019, Rome.-- 1 page, The NW margin of the Alboran Sea (SW Mediterranean) is dominated by terraced plastered drifts cut by downslope turbidite systems. This work focuses on the Quaternary (2.6 Ma to present) seismic stratigraphy and geomorphology of the Guadiaro Canyon (located close to the Strait of Gibraltar) and its vicinity. The work is based on data acquired during the FAUCES surveys (high-resolution bathymetry and seismic profiles).A detailed analysis of the seismic stratigraphy of the Quaternary deposits on the occidental margin of the Guadiaro. Canyon has revealed the presence of a plastered deposit prograding towards the NE and invading the area formerly occupied by the canyon, which has progressively narrowed and constricted due to the lateral accretion of packages of stratified facies on its occidental margin. This narrowing decreased the canyon width from up to 2.6 km at the base of the Quaternary, to 1 km at present; during the same time span the canyon axis moved up to 0.6 km towards the NE. The progradation of the plastered drift inside the canyon is supported by an analysis of the thickness distribution of these deposits, which shows a depocentre (210 ms) parallel to the current trend of the occidental margin of the Guadiaro Canyon and above its former course. Despite the presence of some prograding deposits on the opposite margin, these are only about 20 ms thick and show more frequent and larger erosive events, suggesting the dismantlement of the oriental margin parallel to the progradation of the occidental margin. Furthermore, an area with frequent downslope activity affecting the plastered deposits of the oriental margin of the canyon has been interpreted based on bathymetric and seismic data. This downslope activity is indicated by the presence of two modern slide scars (one almost rectilinear and close to the canyon, at a water depth of 500-550 m; the second curvy and located about 6 km away from the canyon, at a water depth of 375-490 m), and several buried cut-and-fill features headed towards the canyon. The most recent cut-and-fill feature runs almost N-S, and its infill deposits prograde towards the NE.The correlation of progradation vs. erosion and the distribution of depocentres provide evidence of how alongslope deposits have impacted a downslope feature: the progressive invasion of the palaeo-Guadiaro Canyon by contourite deposits has affected its current location and shape. On the other hand, mapping the slide scars and cut-and-fill features has revealed an area with frequent downslope activity, partly dismantling the northern contourite drift and feeding the Guadiaro downslope activity. Together, both the prograding direction of the southern plastered drift and the infill of the channel cut into the northern plastered drift point towards a NE-directed current being the main mechanism driving the interaction between the Guadiaro Canyon and its annexed contourite drifts. This NE alongslope flow may be the consequence of internal waves from the Strait of Gibraltar travelling along the Spanish continental slope, overcoming the background flow of light Mediterranean waters headed towards the strait, Contribution from Project FAUCES CTM2015-65461-C2-R (MINECO/FEDER)

34th International Association of Sedimentologists (IAS) Meeting of Sedimentology, Sedimentology to face societal challenges on risk, resources and record of the past, 10-13 September 2019, Rome.-- 1 page, The Almanzora-Alías-Garrucha canyon system incises the narrow (5 km wide) continental shelf of the Palomares continental margin (SW Mediterranean Sea). The canyon is 74 km long running from west to east almost from the coastline down to 2500 meters water Depth (mwd). The canyon system is constituted by several tributary canyons such as the Almanzora, the Garrucha, the Cabrera and the Alias (from N to S) merging at 1820 mwd and resulting in a single canyon body 4 km wide, following a strait direction for 46 km.Different multibeam echosounder datasets were merged to study the canyon system. A base map belonging to the Spanish Secretary-General for Fisheries (SGP) was recently improved with data recorded in the framework of Fauces project in order to produce 10 to 2 m grid size maps of the Almanzora-Alías-Garrucha canyon. Extensive network of highresolution seismic and parametric profiles visual observations along with ROV system were also recorded. This integration has allowed mapping the morphological variability of the mass-movement features and brings new insights about the processes that shaped the canyon system. Two main areas have been differentiated: (i) the canyon head and upper course (from 7 to up 1400 mwd), where erosion and mass-movements have resulted in dense networks of dendritic gullies, minor scars and falls affecting the canyon walls. These processes have produced a progressive incision and retrogradation of the canyon heads up to almost reach the coastline; (ii) the middle and distal courses (from 1400 to up 2500 mwd), where turbidity flows and related flows have contributed to the progressive incision of the thalweg, floored by bedforms and scars affect the canyon walls. The seafloor of the southern margin of the canyon is highly irregular defining an area of about 262 km that extends from 600 to 2240 mwd affected by a composite mass flow deposits. In contrast, the northern margin presents a set of nested concave-downward scars, with a W-E trend, lengths of 2 to 8 km and slope gradients up to 17º. These recurrent mass-movements have resulted in the enlargement of the canyon and in an asymmetric bathymetric profile.By zooming over the seafloor, through the ROV observations, the canyon walls appear as near-vertical outcrops flaking by instability features . Mass flows deposits, topples/falls and metric isolated blocks are observed along the canyon floor. Although the occurrence of mass-movements is affecting the present-day seafloor, the presence of muddy sediments draping and smoothing the seafloor inside and outside of the canyon may inform about a sub-recent instability activity

Workshop. Alboran Domain and Gibraltar Arc: Geological Research and Natural Hazards - El dominio de Alborán y el Arco de Gibraltar: Investigación geológica y riesgos naturales - Le Domaine Alboran et l'Arch de Gibraltar: Recherche géologique et risques naturels, 16-18 octubre 2019, Granada..-- 2 pages, 1 figure, La integración de observaciones geológicas mar-tierra ha permitido obtener nuevas pistas para comprender los rasgos morfológicos en el Golfo de Vera (Fig. 1). La fisiografía del margen continental está definida por un borde de plataforma localizado a 20-200 m de profundidad, y un talud continental relativamente ancho (60 km) que se extiende hasta unos 2500 m de profundidad, donde se conecta con la cuenca Argelino-Balear. El talud continental es irregular y presenta escarpes, plataformas de talud y cuencas intra-talud. Su morfología comprende una gran variedad de rasgos tectónicos y sedimentarios, siendo los más representativos: i) tres altos estructurales alargados, con orientaciones WSW-ENE a SW-NE, y naturaleza volcánica y metamórfica; ii) tres depósitos de inestabilidad sedimentaria de gran escala, que se extienden desde el talud superior al inferior. Dos de estos depósitos están erosionados por prominentes cañones W-E, de hasta 80 km de longitud; iii) depósitos de inestabilidad sedimentaria de menor escala, de pocos a decenas de kilómetros de longitud; y iv) rasgos contorníticos en el talud superior (Fig. 1). En la cuenca adyacente, los rasgos más destacados son numerosas alineaciones (en su mayoría SW-NE) de estructuras de intrusión relacionadas con los diapiros de sal mesiniense (Fig. 1). La formación de estos rasgos fisiográficos y morfológicos es consecuencia de la deformación del margen continental en el marco de la colisión NW-SE de las placas Euroasiática y Africana. En este contexto, la deformación tectónica se ve favorecida por la presencia de la corteza continental delgada del margen continental, entre la corteza oceánica más resistente de la cuenca Argelina-Balear y la gruesa corteza continental de la Cordillera Bética oriental. El Golfo de Vera, que se encuentra dentro del Arco de Aguilas, está afectado por la indentación hacia el noroeste de las Zonas Internas de las Béticas y el desarrollo de la falla sinistra de Palomares (Fig. 1). En contraste con los pliegues W-E en las Cordilleras Béticas centro-orientales, los altos SW-NE a WSWENE en el talud continental, representan antiformas resultantes de la acomodación de la indentación tectónica (Fig. 1). Esta determina el basculamiento del margen continental lo cual provoca cambios de pendiente y en el nivel base del margen. Este hecho, junto con la presencia de sales mesinienses, podrían ser responsables de la inestabilidad sedimentaria dominante en el talud continental del Golfo de Vera. Aquellas áreas del talud superior donde la actividad de las corrientes de fondo es relativamente más importante, favorecen la formación de una terraza contornítica y crestas contorníticas de tipo adosada y elongada separada (Fig. 1). La indentación tectónica también habría condicionado la distribución y orientación de las estructuras de intrusión relacionadas con los diapiros de sal mesiniense (Fig. 1)

European Geosciences Union (EGU) General Assembly, 7-12 April 2019, Vienna, Austria.-- 1 page, Based on seismic geomorphology, geomorphometry, sedimentology and tectonic analysis, new clues have been obtained to understand one of the margins with the most complex morphology in the Spanish Mediterranean. The physiography of the Gulf of Vera comprises a continental shelf break located at 20-200 m water depth and a relatively wide (60 km) continental slope that extends down to about 2500 m water depth, where it connects with the Algero-Balear basin.. The slope profile is irregular, with large escarpments, slope platforms and intraslope basins. Its morphology is defined by a great variety of tectonic and sedimentary features, being the most striking ones: i) three main elongated structural highs, with different trends (WSW-ENE to SW-NE) and nature (volcanic and metamorphic); ii) three large scale mass-transport deposits (MTDs) extending from the upper to the lower slope. Two of them are incised by prominent W-E canyons (up to 80 km long) whose enlargement is controlled by the gravitational instability of their walls; iii) minor-scale MTDs (few to tens of kilometres long) that spread practically throughout the rest of the continental slope; and iv) local contourites in the upper slope. In the adjacent basin, the most outstanding seafloor features are numerous alignments (mostly SW-NE) of piercement structures related to the Messinian salt diapirs. The formation of those features is consequence of the deformation of the continental margin in the frame of the NW-SE Eurasian-African plate collision. In this setting, tectonic deformation is favoured by the presence of the thin continental crust of the continental margin, between the more resistant oceanic crust of the Algero-Balear basin and the thick continental crust of the eastern Betic Cordillera. The Gulf of Vera, that is located within the Aguilas tectonic indentation domain, is defined by northwestward indentation of the Internal Zones of the Betics and the related development of the sinistral Palomares fault. Contrasting with the W-E folds in the central-eastern Betic Cordilleras, the SW-NE to WSW-ENE elongated highs in the continental slope, represent antiformal structures that are consequence of the accommodation of the tectonic indentation. This recent deformation determines the tilting of the margin that may provoke changes in the slope gradients and in the margin base-level. This fact together with the presence of Messinian salts could be responsible of the significant sedimentary instability displayed by the Gulf of Vera continental slope. Those areas of the upper slope where the bottom currents activity is relatively more important, a contouritic slope terrace is sculpted. The tectonic indentation would have also conditioned the distribution and trend of the piercement structures related to the Messinian salt diapirs

34th International Association of Sedimentologists (IAS) Meeting of Sedimentology, Sedimentology to face societal challenges on risk, resources and record of the past, 10-13 September 2019, Rome.-- 1 page, Turbidite systems contain global and local palaeoenvironmental information. The distal Almeria Turbidite System (ATS), located in the eastern Alboran Sea, is a sedimentary system developed in an active tectonic and semi-confined setting that extends from a wáter depth of 1600 m to 1950 m. This work presents the chronostratigraphy of 269 ka defined after an analysis of the very high-resolution seismic data (TOPAS profiles), and the oxygen isotope record obtained of core ODP-977. The distal ATS comprises the following architectural elements: a leveed-channel; distributary channels; and several distributary channel fringes forming a lobe complex. Three seismic units, 1 to 3, bounded by three discontinuities (the oldest being R1 and the youngest R3) can be correlated with marine isotope stages (MIS) MIS 8, MIS 6, and MIS 4, respectively. Three channel-levee complexes (the oldest being 1 and the youngest 3), intercalated with mass-transport deposits and overlain by hemipelagites, have been identified within each seismic unit. The spatial and temporal distribution of these deposits allow us to divide their sedimentary history over the last 269 kyr into three periods. Unit 1 was deposited in Period 1 (269-190 ka), with the development of channel-levee 1. The relatively large dimensions (450 km and 11 km3) of this channel-levee could be related to significant sediment supply during the sea-level lowstand of MIS 8. The semi-confined setting and palaeotopography conditioned the sediment distribution along the base-of-slope and Eastern Alboran Basin. Unit 2 was deposited in Period 2 (190-70 ka). The development of channel-levee 2 with similar dimensions to its predecessor (300 km and 9 km3) initiated during the sea-level lowstand of MIS 6. The lateral migration to the NE of these deposits would have been related to avulsion processes in the main channel and accommodation space. Unit 3 was deposited in Period 3 (70 ka to present). The development of the somewhat smaller, turbiditic channel-levee 3 (180 km2 and 3 km3) began during the sea-level lowstand of MIS 4. This strong decrease in dimension suggests a decrease in turbidite activity. This change could have been related to relatively less land sediment being input, as consequence of the relatively minor sea-level fall (~80 m) in MIS 4 compared to the earlier MIS 6 and MIS 8, which were defined by falls of ~120 m. There was, therefore increased submarine canyon activity and more slope instability processes during the low stand stages, while during the highstand stages much of the terrigenous sediments remained trapped on the shelf, and the distal ATS was dominated by a hemipelagic setting

34th International Association of Sedimentologists (IAS) Meeting of Sedimentology, Sedimentology to face societal challenges on risk, resources and record of the past, 10-13 September 2019, Rome.-- 1 page, The combination of surface and vertical imagery obtained in the framework of the FAUCES and DAMAGE projects, has allowed us to improve the physiographic characterization and to map the morphological features that characterize the Gulf of Vera (southwestern Mediterranean).On the Continental Slope: A large plastered drift shaped by a contouritic terrace is mapped along the upper slope. Mass-movement features are evidenced by disappearance of sediment or by its deformation; six types of features are characterized. (i) two relatively long and asymmetric canyon systems, the Garrucha and Cabo de Gata, that incise the entire slope; (ii) smaller canyons and gullies, mostly identified in the north where the slope narrows drastically; (iii) gully like landslide troughs comprise slide scars that continues downslope defining troughs that resemble a ravine or gully morphologies; (iv) mass-flow deposits extending far away from these troughs; (v) a large mass-transport deposit (MTD) affecting the entire continental slope is mapped to the north; and (vi) the slides appear locally as clusters of rotational and translational slide scars associated with mass-flow deposits.On the Basin: Asymmetric beforms with rectilinear and sinuous crests occur at the distal end of the Garrucha canyon floor. Mass-movement features comprising seafloor lineations, are mapped in a bypass zone of unchannelized mass-flows deposits coming from the smaller canyons. In addition, a cluster of diapiric crests appears aligned roughly following SW-NE and NNW-SSE directions.The oceanography as well as Deep structure of the margin and land, help to understand the present-day geomorphology. Contourites form under the action of the Mediterranean Intermediate Water. The large canyons were excavated during the Messinian Salinity Crisis and their pathways are conditioned by the basement structures. The mass-movement feature distribution seems governed by the interplay between the gradients and the irregular geometry of the slope, which have influenced the mechanics of the downslope movements and runout distances. They have occurred quasi-continuously during the Plio-Quaternary, contributing to the progressive mass-wasting or ¿exfoliation¿ of the open slope and the enlargement of the canyons. The MTD appears to be related to the flow of the unlithified Messinian salt that acts as a weak layer favouring the sliding downslope. Diapir crests indicate those Messinian salts have penetrated the Plio-Quaternary sediments, through a set of fractures formed by the downslope flow of the salt. The marine geophysical data alone, however, does not explain why the margin of the Gulf of Vera is a margin in continuous mass-wasting during the Plio-Quaternary. The land morphology bordering the Gulf of Vera gives the clues. This area is structurally dominated by the Arc of Aguilas to the north, the Palomares Fault to the west and the probable oceanic crust of Algerian-Balearic basin to the south. The continental indentation of the Arc of Aguilas produces a tectonic southeastwards tilting of the whole land-sea region that may influence the steepness of the seafloor and its quasi-continuous readjustment that reduced substantially the stability of seafloor sediments. In this setting, the continental margin was built up affected by continuous mass movement structures

Workshop. Alboran Domain and Gibraltar Arc: Geological Research and Natural Hazards - El dominio de Alborán y el Arco de Gibraltar: Investigación geológica y riesgos naturales - Le Domaine Alboran et l'Arch de Gibraltar: Recherche géologique et risques naturels, 16-18 octubre 2019, Granada..-- 2 pages, Seafloor of the Alboran Sea is characterized by several minor and major features related to tectonic activity. Minor features are basically alignments of tectonic scarps, longitudinal and rhombic depressions, longitudinal ridges and smooth elongated bulges. These morphotectonic features are generated by a penetrative system of faults and folds that have been active along the Quaternary deforming and displacing the seabed. These structures have been evidenced by means of multibeam bathymetry mosaics and subsurface very high resolution parametric and high resolution seismic (airgun, sparker) profiles, which allow to analyze their morphologic characteristics and the related deformation. The active Quaternary structures are constituted by three families of strike-slip faults that work as a conjugated system. The first one has a WNW-ESE to NW-SE trend and right-lateral shear movement with extensional secondary component; this group correspond to structures as the Yussuf Fault that bounds the Alboran ridge to the east, the Averroes Fault that displaced the Adra ridge, and several structures in the northern Alboran Basin margin as the Adra and Balanegra faults. The other two have respectively NE-SW and NNE-SSW geometry and a left-lateral shear displacement, the first family corresponds basically to the La Serrata-Carboneras Fault that has also push and swell segments related to reverse secondary component, and the second group is constituted by several fault zones extended from close the Alhoceima region in northern Africa through the Alboran Ridge to nearby the Adra region in the south of the Iberian Peninsula. The NNE-SSW system is so marked at the Motril-Djibouti marginal plateau where this family is constituted at least by five left-lateral fault zones that are characterized on the seafloor by corridors of fault escarpments and tectonic depressions, both grabens and halfgrabens, featured as minor pull-apart basins. The corridors lengths vary between 18 and 48 km and their widths between 0.2 and 3.9 km. A dense secondary N-S normal faulting is related to the strike-slip movement of the main faults, and several intermediate normal fault zones are located between them. These fault systems are extended south-westwards of the Motril-Djibouti marginal plateau, between the Banks of Djibouti and the Ibn-Batouta seamount, where these faults have a splay configuration on the seafloor, except the eastern one, that corresponds to boundary fault of this fault system. The eastern fault zone of the NNE-SSW family is the Al Idrissi fault prolongation, and is strongly marked by development of longitudinal ridges features, generated by push and swell structures, to the west of the Alboran ridge that appoint to a reverse secondary component of this fault in this area. Likewise, to the north of the Motril-Djibouti marginal plateau, it has been recognized the presence of N-S trending normal faults and NE-SW anticline folds affecting the seabed. The northern margin of the Alboran Sea is located to the south-west of the Eastern Betics Seismic Zone. The distribution pattern of seismicity epicentres in this area has a good correlation with the describe NNE-SSW left lateral strike slip faults. These active fault zones are currently responsible of a large part of the regional seismicity

67 Sesión Científica de la Sociedad Geológica de España, 22-23 de noviembre de 2019, Peñarroya - Pueblonuevo, Córdoba

34th International Association of Sedimentologists (IAS) Meeting of Sedimentology, Sedimentology to face societal challenges on risk, resources and record of the past, 10-13 September 2019, Rome.-- 1 page, The Garrucha harbour, located in the Gulf of Vera (SW Mediterranean) was built in the 30¿s of the 20th century, and in the last decades different expansion works have been carried out due to its increasing commercial activity. Due to this expansion, the infrastructure interacts with the Garrucha canyon head. The Garrucha canyon is a northern tributary of the Almanzora-Alías-Garrucha canyon system with its shallowest rim located close to the shore, at 7-20 meter water depth. The canyon is affected by sedimentary processes producing progressive entrenchment and retrogradation that may represents a potential hazard for the harbour.The aim of this work is to present a preliminary assessment of the submarine slopes stability in the surrounding area (2 km) of the harbour based on the results of limit equilibrium analysis carried out in six representative profiles, and the definition of the geotechnical units in the first 20 m of the seafloor. To do so, high resolution bathymetry, sediment sampling and in situ testing (7 CPTu) recently obtained in the framework of Fauces project have been used. Grain size analysis, Atterberg limits and oedometer, direct shear and triaxial tests allowed to define the geotechnical properties of sediments. The geotechnical characterization and the in situ tests (CPTu) allowed to define three geotechnical units (GU) in the area. GU 1, predominantly located in the harbour vicinity, is a granular and non-plastic sediment, with 75% of sand content and strength parameters defined by 27.1° effective friction angle (¿¿) and null effective cohesion (c¿). The second granular unit, GU 2, with a higher fine content (59 %) is a ML soil which shear strength is governed by an effective cohesion of 18.2 kPa and an effective friction angle of 26.4°. Finally, a cohesive normally consolidated GU 3 has been defined, with fine content > 90% and low plasticity. In these materials, undrained is the most suitable condition for stability analysis, and therefore, Su values from 20 to 100 kPa have been assigned according the CPTu and TUU tests. Slope stability analyses were carried out using limit equilibrium slope stability software, calculating the Factor of Safety (FS) with the Bishop simplified method. For the six profiles considered, and under static conditions, the FS obtained were higher than 1, but close to this value in the locations where GU 3 is present. For these particular profiles, non-equilibrium resulted when the seismic load for this area was taken into account. As a conclusion, the results obtained so far indicate the existence of a geological hazard associated with the generation of submarine landslides in the surrounding area of the Garrucha harbour considering a seismic activity context, and they would be preferently developed in locations where UG 3 appears. The nearest area to the harbour infrastructure, where granular materials predominate, is more stable; however, its granulometric nature points to potential liquefaction, and therefore, a more deep study about its dynamic behaviour is needed

4th Fault2SHA Workshop, Fault Complex Interaction: Characterization and Integration into Seismic Hazard Assessment (SHA), 3-5 June 2019, Barcelona, Seafloor of the Alboran Sea is characterized by a penetrative system of tectonic structures that are well defined both by displacement and folding of Quaternary sedimentary units and formation of several marked morphological features related to contemporary faulting activity. These structures are evidenced in multibeam bathymetry mosaics and subsurface parametric and high resolution seismic (airgun, sparker) profiles, which allow to analyze their strong deformation. The pattern of seismic epicentres distribution has also a good correlation with these structures. The group of Quaternary structures is constituted by three families of strike-slip faults that they work as a conjugated system. The first one has a WNW-ESE to NW-SE trend and right-lateral shear movement, and the other two have respectively NE-SW and NNE-SSW geometry and a left-lateral shear displacement. The activity of NNE-SSW family is recent than the NE-SW one since they displace them. Likewise it has been recognized the presence of N-S trending normal faults and NE-SW anticline folds. The Motril-Djibouti marginal plateau (northern margin of Alboran Sea) on the southwestward prolongation of the Eastern Betic Shear Zone, is crossed by at least eight active fault zones of NNE-SSW direction. They are characterized on the seafloor by corridors of fault escarpments and tectonic depressions, both grabens and halfgrabens, as minor pull -apart basins. The corridors length vary between 18 and 48 km and their widths between 0.2 and 3.9 km. A dense secondary N-S normal faulting is related to the strike-slip movement of the main faults. The main fault zones currently are responsible of a large part of the regional seismicity. The eastern fault zone corresponds to the northern prolongation of the Al Idrissi fault

5 pages, 1 figure, The Miocene is an essential period in the configuration of the present-day relief of the Betic Cordillera and the South Iberian continental margin, which determined the structure and evolution of the Neogene sedimentary basins (Fig. 3.1). The crustal thinning processes that occurred during the early and middle Miocene, after the main metamorphic events, generated major low-angle normal faults that separate the main metamorphic complexes. Although a wide variety of tectonic models have been proposed for this setting, most of them are related to delamination or to subduction with associated roll-back. During the late Miocene, the relatively flat and low relief of the continental crust facilitated the accumulation of sedimentary deposits, which are interlayered with volcanic rocks in the eastern Betic Cordillera and Alborán Sea. The continuous Eurasian-African convergence finally produced regional uplift since the late Miocene and the development of large late regional E-W to NE-SW folds, which determine the main reliefs