Tectonic Control on Sedimentary Dynamics in Intraplate Oceanic Settings: A Geomorphological Image of the Eastern Canary Basin and Insights on its Middle-Upper Miocene to Quaternary Volcano-Tectonic-Sedimentary Evolution

This paper integrates sedimentary, tectonic and volcanic geological processes inside a model of volcano-tectonic activity in oceanic intraplate domains related to rifted continental margins. The study case, the eastern Canary Basin (NE Atlantic), is one of the few places in the world where giant MDTs and Quaternary volcanic and hydrothermal edifices take place in intraplate domains. In this paper, we analyse how two structural systems (WNW-ESE and NNE-SSW) matching with the oceanic fabric control the location of volcanic systems, seafloor tectonic reliefs and subsequently the distribution of main sedimentary systems. Linear turbidite channels, debris flow lobes and the lateral continuity of structural and volcanic reliefs follow a WNW-ESE trend matching the tracks of the oceanic fracture zones. Furthermore, escarpments, anticline axes and volcanic ridges follow a NNE-SSW trend matching normal faults delimiting blocks of oceanic basement. The morpho-structural analysis of all the above geomorphological features shows evidence of a volcanic and tectonic activity from the middle–upper Miocene to the Lower–Middle Pleistocene spread over the whole of the eastern Canary Basin that reached the western Canary Islands. This reactivation changes the paradigm in the seamount province of Canary Islands reported inactive since Cretaceous. A tecto-sedimentary model is proposed for this period of time that can be applied in other intraplate domains of the world. A tectonic uplift in the study area with a thermal anomaly triggered volcanic and hydrothermal activity and the subsequent flank collapse and emplacement of mass transport deposits on the Western Canary Slope. Furthermore, this uplift reactivated the normal basement faults, both trending WNW-ESE and NNE-SSW, generating folds and faults that control the location of turbidite channels, escarpments, mass transport deposits and volcanic edifices.Versión del edito

Discovering the Fine-Scale Morphology of the Gulf of Cádiz: An Underwater Imaging Analysis

The dense and deep water flow that leaves the Mediterranean Sea to the Atlantic flows through the upper and middle slope of the Gulf of Cádiz as a powerful bottom stream that model sand interacts with bathymetry. The detailed analysis of underwater images,obtained with a photogrammetric sled in the central area of the upper and middle slope of the Gulf of Cádiz, together with multibeam bathymetry and oceanographic and sediment types data, has allowed conducting a detailed study of the seafloor microtopography and the predominant oceanographic dynamics in the study area. Different fine-scale spatial bedforms were identified, such as ripples, dunes, burrows, mounds, obstacle marks, rock bottoms, and low-roughness bottoms using underwater images. Besides, a geostatistical study of the different video transects studied was carried out and allowed us to differentiate three types of bottoms depending on the processes that affect their microtopography.En prens

Morfometría de montículos submarinos del talud inferior del margen continental canario (O de las Islas Canarias): Análisis basado en un MDT

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

Modelización de los end-members para reconocer fuentes de aporte sedimentario en contornitas: un caso de estudio en el Mar de Alborán

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

Los Montes Submarinos de la Plataforma Marginal de Motril, Mar de Alborán: Interacción con las Masas de Agua Profunda

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First faunistic results on Valencia (Cresques) Seamount, with some ecological considerations

The living and dead fauna of Valencia Seamount, a deep promontory in the middle of the Balearic Basin which summit is at ca. 1100m depth, is described by first time based in a rock dredge perfomed in a sedimentary area of the summit Mount. Surface-feeder polychaetes (the Paraonidae Levinsenia gracilis and Terebellidae as dominant), and taxodont bivalves (Ledella messanensis and Yoldiella ovulum) were the main species of benthos. We found alive remains of the bamboo coral Isidella elongata, a vulnerable, habitat-forming species in the deep Mediterranean. Benthos density was low (0.6 organisms/2 dm3 mud). Thanatocoenosis evidenced a rather moderate diversity on benthic bivalves (11 species) and gastropods (9 species) also dominated by surface deposit feeders. Fish (identified/ quantified from sedimented otoliths) showed diversified and abundant mesopelagic fauna, mainly Myctophidae. More interestingly, we highlighted among benthopelagic fish the occurrence of recruits of Merluccius merluccius, Micromesistius poutassou, or Hymenocephalus italicus, all species that live in the neighboring slopes of the Iberian Peninsula and the Balearic Islands at quite shallower depths (at 100-700 m) than their distribution in the Valencia Seamount summit (1102–1130 m) based on the deposited otoliths found. Some ecological aspects were discussed and the necessity to consider the deep Valencia Seamount as a potential area that should be under protection.En prensa

Mapping giant mass transport deposits (MTDs) for delineating the extended Continental Shelf of Spain to the West of Canary Islands according UNCLOS Art. 76

European Geosciences Union General Assembly (2017. Viena)On 19 December 2014, Spain presented a third partial submission for the delineation of the Extended Continental in the area west of the Canary Islands to the Commission on the Limits of the Continental Shelf (CLCS) according to the United Nations Convention on the Law of Sea (UNCLOS). The Canary Islands are located within a NE-SW 1,350 km long ridge of hotspot-inferred volcanic islands and seamounts (composed by more of 100, from Lars to Tropic seamounts). This submission has been documented with an extensive dataset specifically obtained for the project during ten oceanographic cruises between 2010 and 2014 aboard the Spanish research vessels Hespérides, Sarmiento de Gamboa and Miguel Oliver. This new dataset allows to investigate an area of 440,000 km2 with acoustic backscatter images and multibeam echosounder bathymetric (MBES) data (Simrad EM-12, EM-120 and EM-302, and Atlas HYDROSWEEP DS), a dense network of 65,800 km of very-high resolution (VHR) seismic lines (including chirp parametric source TOPAS PS-18 and Atlas PARASOUND P-35) and 4,471 km of multichannel seismic reflection lines (MCS) acquired with an array of air-guns yielding a total volume of 4,600 inch3 (75.38 L) and a 3,500 m long streamer composed of 280 channels.Instituto Geológico y Minero de España, EspañaInstituto Español de Oceanografía, EspañaInstituto Hidrográfico de la Marina, Españ

Morphological characterization of contourite and mass-wasting recent processes at the Guadalquivir Bank Margin uplift, Gulf of Cádiz

The Gulf of Cadiz records the interplay of a variety of sedimentary processes related to the circulation of water masses. The most important one is the Mediterranean Outflow Water (MOW) that exits the Mediterranean Sea, but other water masses also affect the seafloor, with complex variations along time and space. This work studies the interplay between oceanographic and gravitational sedimentary processes on the Guadalquivir Ridge, based on bathymetry and high-resolution seismic profiles. A series of morphological features including flat terraces, circular/elliptical depressions, semicircular scarps and valley-shaped features are analysed in order to better understand the interaction between water masses circulation and mass-wasting processes of the Gulf of Cadiz.Versión del edito

From hyperextended rift to convergent margin types: mapping the outer limit of the extended Continental Shelf of Spain in the Galicia area according UNCLOS Art. 76

European Geosciences Union General Assembly (2017. Viena)Spain presented on 11 May 2009 a partial submission for delimiting the extended Continental Shelf in respect to the area of Galicia to the Commission on the Limits of the Continental Shelf (CLCS). The Galicia margin represents an example of the transition between two different types of continental margins (CM): a western hyperpextended margin and a northern convergent margin in the Bay of Biscay. The western Galicia Margin (wGM 41º to 43º N) corresponds to a hyper-extended rifted margin as result of the poly-phase development of the Iberian-Newfoundland conjugate margin during the Mesozoic. Otherwise, the north Galicia Margin (nGM) is the western end of the Cenozoic subduction of the Bay of Biscay along the north Iberian Margin (NIM) linked to the Pyrenean-Mediterranean collisional belt.Instituto Geológico y Minero de España, EspañaCentro Oceanográfico de Málaga, Instituto Español de Oceanografía, EspañaInstituto Hidrográfico de la Marina, Españ