Morphostructure at the junction between the Beata ridge and the Greater Antilles island arc (offshore Hispaniola southern slope)

Oblique convergence between the Caribbean plate's interior and the inactive Greater Antilles island arc has resulted in the collision and impingement of the thickened crust of the Beata ridge into southern Hispaniola Island. Deformation resulting from this convergence changes from a low-angle southward-verging thrust south of eastern Hispaniola, to collision and uplift in south-central Hispaniola, and to left-lateral transpression along the Southern peninsula of Haiti in western Hispaniola. Using new swath bathymetry and a dense seismic reflection grid, we mapped the morphological, structural and sedimentological elements of offshore southern Hispaniola. We have identified four morphotectonic provinces: the Dominican sub-basin, the Muertos margin, the Beata ridge and the Haiti sub-basin. The lower slope of the Muertos margin is occupied by the active Muertos thrust belt, which includes several active out-of-sequence thrust faults that, were they to rupture along their entire length, could generate large-magnitude earthquakes. The interaction of the thrust belt with the Beata ridge yields a huge recess and the imbricate system disappears. The upper slope of the Muertos margin shows thick slope deposits where the extensional tectonics and slumping processes predominate. The northern Beata ridge consists of an asymmetrically uplifted and faulted block of oceanic crust. Our results suggest that the shallower structure and morphology of the northern Beata ridge can be mainly explained by a mechanism of extensional unloading from the Upper Cretaceous onward that is still active residually along the summit of the ridge. The tectonic models for the northern Beata ridge involving active reverse strike–slip faults and transpression caused by the oblique convergence between the Beata ridge and the island arc are not supported by the structural interpretation. The eastern Bahoruco slope an old normal fault that acts as a passive tear fault accommodating the sharp along-strike transition from low-angle thrusting to collision and uplifting.Universidad Complutense de Madrid - Proyecto Plan Nacional: GEODINÁMICA DEL NORTE DEL CARIBE: SECTOR REPÚBLICA DOMINICANA-HAITI (NORCARIBE).Versión del edito

MAPPING THE SPAIN´S EXCLUSIVE ECONOMIC ZONE IN THE GALICIAN MARGIN

MAPPING THE SPAIN´S EXCLUSIVE ECONOMIC ZONE IN THE GALICIAN MARGIN Gómez Ballesteros, M.1(*), González-Aller, J-D. 2, Martín Dávila, J. 3, Carbó, A., 4, Somoza, L. 5, Druet, M. 1, Martínez-Espinosa, S. 2, Catalán, M. 3, Muñoz, A. 4, León, R 5 1 Instituto Español de Oceanografía / C/. Corazón de María, 8, 28020 Madrid 2 Instituto Hidrográfico de la Marina / Pl. San Severiano, 3, 11007 Cádiz 3 Real Observatorio de la Armada, C/. Cecilio Pujazón s/n 11100Cádiz 4 Universidad Complutense de Madrid / Av Séneca, 2, 28040 Madrid 5 Instituto Geológico y Minero de España, Calle de Ríos Rosas, 23, 28003 Madrid (*)Corresponding Author: [email protected] In the context of the Hydrographic and Oceanographic Research of the Spain´s Exclusive Economic program (ZEEE), operated jointly by Instituto Hidrográfico de la Marina (IHM) and Real Observatorio de la Armada (ROA) working in close collaboration with the Instituto Español de Oceanografía (IEO), Universidad Complutense de Madrid (UCM) and Instituto Geológico y Minero de España (IGME) have conducted seven oceanographic cruises in Galician waters (EEZ -01 -02 ZEE , ZEE -03, ZEE -06 -07 ZEE , ZEE- ZEE- 08 and 09). The main objective of the Spain´s Exclusive Economic Zone project is mapping the seafloor, carrying out a systematic bathymetric survey of the 200 miles that comprise this area. In addition, as secondary objectives were performed acquiring that complement other geophysical parameters characterizing the seafloor and seabed from the knowledge of other variables such as the Terrestrial Magnetic Field , Terrestrial Gravity field, sound velocity and seabed internal structure. For the acquisition of detailed and accurate information during these cruises, carried on board the BIO Hespérides, high-resolution geophysical techniques were used to compile the data and the bathymetry of the region was mapped using a multibeam system during which 100 per cent coverage was obtained. At the same time high-resolution parametric seismic reflection profiles, as well as gravity and magnetic, were also recorded in the survey areas. These systems provide data on bathymetry, quality seafloor, acoustics backscatter , gravimetry, magnetometry and subsurface structure and require the use of precise positioning techniques, so were used in conjunction with GPSD and inertial navigation systems. As a result of these oceanographic researches and post-processing, analysis and interpretation of the whole acquired data, a synthesis of 6 maps were published with 1:500.000 scale and corresponding to Bathymetric map, Geomorphology map, Geomagnetic Anomaly map, Bouguer and Free Air Anomaly maps and backscatter map. REFERENCIAS J. Martín Davila, M. Catalán, M. Larrán, Sección de Hidrografía del IHM, A. Carbó, A. Muñoz-Martín, JL Granja, P. Llanes, L. Somoza, R. León, F.J. Gonzalez, M. Gómez-Ballesteros, M. Druet, and J. Acosta, 2014: Zona Económica Exclusiva Española (ZEEE): Margen Continental Gallego. Mapas Generales de batimetría, de anomalías Geomagnéticas, Graviméwtricas de Aire Libre y Bpouguer, Geomorfológico y Mosaico de Imágenes de Reflectividad (E. 1:500.000). Ministerio de Defensa. Secretaria General Técnica, NIPO: 083-12-230-3, DL: M-39518-201

Deep crustal structure and continent-ocean boundary along the Galicia continental margin (NW Iberia)

The Galicia continental margin is a magma-poor rifted margin with an extremely complex structure. Its formation involves several rifting episodes during the Mesozoic in the vicinity of a ridge triple junction, which produces a change in the orientation of the main structures. In addition, there is an overimposed Cenozoic partial tectonic inversion along its northern border. Although this continental margin has been widely studied since the 70’s, most studies have focused on its western part in the transition to the Iberia Abyssal Plain, and there is a significant lack of information on the north and northwestern flanks of this margin. This fact, along with its great structural complexity, has resulted in the absence of a previous comprehensive regional geodynamic model integrating all the processes observed. In the present study we integrate a large volume of new geophysical data (gravity, swath bathymetry and 2D multichannel reflection seismic). Data come from the systematic mapping of the Spanish EEZ project which provides a dense grid of gravity data and full seafloor coverage with swath bathymetry, and from the ERGAP project which provides serially-arranged 2D seismic reflection profiles across the NW Iberia margin. The combined interpretation and modelling of this new information has arisen significant constraints on the origin, the deep crustal structure and the physiographic complexity of the margin, as well as on the characterization of the along- and across-strike variation of the ocean-continent transition along NW Iberia margin. The analysis of this information leads us to propose a conceptual model for the initiation of the tectonic inversion of a magma-poor rifted margin. Finally, a framework for the geodynamic evolution of the Galicia margin has been constructed, involving three main stages: A) an early stage from the end of rifting and oceanic drift in the Bay of Biscay (Santonian); B) an intermediate stage with the beginning of tectonic inversion in the north and northwestern Iberia margin (Campanian-Paleocene) mainly concentrated along the exhumed mantle zone; and C) a final stage of compressive deformation (Eocene-Oligocene) affecting both the continental and the oceanic crust, evidenced by large dip-slip thrusting.0,000

Deep-sea benthic habitats modeling and mapping in a NE Atlantic seamount (Galicia Bank)

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Geomorphology of the Avilés Canyon System, Cantabrian Sea (BayofBiscay)

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

Cold-water corals research in the lab and in the field: (1) growth rates of four CWC species maintained in aquaria, (2) new research areas: the Galicia Bank and the Avilés canyon (Atlantic and Cantabrian Sea), a scientific and methodological approach

Growth rates of 4 Cold-water Coral (CWC) species (Madrepora occulata, Lophe/ia pertusa, Desmophyllum cristagalli and Dendrophyllia cornigera) from the Mediterranean Sea have been measured under the same and controlled laboratory conditions over a nine months period. Results showed that M. occulata grew faster than the other three species, which presented similar growth rates. These results are discussed and also compared with the growth of tropical coral species maintained in aquaria, but in different light and temperature conditions, which corresponded to the usual culture conditions of these corals. It appeared that the zooxanthellate tropical coral Galaxea fascicularis exhibited similar growth rates than the CWC M. oculata. Further we present new research areas on the Atlantic and Cantabrian continental margin, the Galicia Bank and the Aviles canyon, which are part of the zones studied in the Spanish LIFE project INDEMARES, as well as possible targets as Marine Protected Areas (MPAs) for the NATURA 2000 network. Both areas are studied considering an ecosystem approach, aboarding an integrated study of the physical scenario (hydrography, geomorphology), all ecosystem compartments (fish, endo-, epi-, and suprabenthic and benthopelagic fauna) and the trophic relationships between them. All this information, together with the study of the impact of the fisheries working in the areas, will be integrated in a trophodynamic mass-balance model and will be used to identify vulnerable ecosystems (VE) (as the CWC habitats are) and essential fish habitats (EFH). This methodological approach offers a holistic view of these deep-sea ecosystems and can be used to design more effective and successful management strategies for MPA

Shallower structure and active process in the northern Hispaniola offshore margin (Dominican Republic): Preliminary results

El margen submarino del norte de La Española registra el proceso de colisión activa entre los Bancos de las Bahamas y el arco isla. Esta colisión ha producido numerosos terremotos causando cuantiosos daños en la costa norte de la isla. La campaña NORCARIBE (2013) combinó la adquisición sistemática de datos geofísicos de todo el margen subductivo, especialmente en la zona de República Dominicana, proporcionando una información continua y de alta resolución. Esta información ha permitido estudiar con detalle la variación transversal y longitudinal del margen subductivo caracterizado por la Fosa de la Española (FE) y el Cinturón Deformado Septentrional (CDS). Este margen compresivo presenta una estructura imbricada con vergencia hacia el norte y segmentada por zonas de transferencia limitando la longitud máxima de las fallas inversas. Existen numerosas evidencias de deformación activa que deben ser consideradas en futuros estudios sobre la evaluación de la peligrosidad sísmica y tsunamigénica en la región, así como para la evaluación de recursos marinos y la ordenación del territorio de la República Dominicana.The northern Hispaniola offshore margin records the active collision between the Bahamas Banks and island arc. This collision is associated to the occurrence of numerous earthquakes that caused significant damages in the northern coast of the island. The NORCARIBE cruise carried out in 2013 combined the systematic acquisition of geophysical data in the whole collisional margin, mainly focused in Dominican Republic, providing continuous and high resolution information. This new information has allowed to study with more detail the along- and across-strike structure of the collisional margin characterized by the Hispaniola trench and the Northern Deformed Belt. This compressive margin shows a N-verging imbricate structure segmented along strike by transfer zones limiting the maximum fault length. There are numerous evidences of active deformation that have to be considered in future studies on the seismic and tsunamigenic assessment in the region, as well as for the assessment on marine resources and development planning of Dominican Republic.Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEMinisterio de Economía y Competitividad (MINECO)Universidad Complutense de Madridpu