Estructura y evolución geodinámica del extremo noreste del margen continental catalán durante el Neógeno

The neogene structure and geodynamic evolution of the continental margin between the Cape Bagur and the Cape Creus, has heen studied by means of multichannel seismic profiles. This structure is explained in a regional geodynarnic framework: the opening of the Western Mediterranean and the changes of the relative motion between the European and Afncan plates (NNE in the Latest Oligocene and NO in the Tortonian age). Major margin structures consist of a set of structural highs, grabens and semigrabens infilled by Neogene-Quaternary sediments, whose thicknesses range from 400 m near the coast to 4.000 m in the continental slope. This structures are associated to NE-SW to N-S and NWSE to WNW-ESE fault systems. The NE-SW to N-S system produces the structural configuration of the continental margin and the KW-SE to WNW-ESE is associated to the main basins: Rosas and Bagur. Three main units have been differenciated in the seismic profiles overlying a pre-Neogene basement: the two lowest units (Oligocene?- Lower Miocene and Middle-Upper Miocene units) are associated with the development of neogene deposits, whilst the third consist of post-Messinian deposits (Plio-Quaternary unit). The proposed geodynamic evolution of the area includes two stages: (1) latest Oligocene-Burdigalian rifting where extensión was accomodated by NE-SW normal faults and NW-SE transfer faults related to the Burdigalian drifting, (2) Tortonian to Present stage characterized by the blocking of the NE-SW faults and the extensional development of the NW-SE fault trend. Each stage involves a basin geometry and a style of faulting

Estructura y evolución geodinámica del extremo noreste del margen continental catalán durante el Neógeno

The neogene structure and geodynamic evolution of the continental margin between the Cape Bagur and the Cape Creus, has heen studied by means of multichannel seismic profiles. This structure is explained in a regional geodynarnic framework: the opening of the Western Mediterranean and the changes of the relative motion between the European and Afncan plates (NNE in the Latest Oligocene and NO in the Tortonian age). Major margin structures consist of a set of structural highs, grabens and semigrabens infilled by Neogene-Quaternary sediments, whose thicknesses range from 400 m near the coast to 4.000 m in the continental slope. This structures are associated to NE-SW to N-S and NWSE to WNW-ESE fault systems. The NE-SW to N-S system produces the structural configuration of the continental margin and the KW-SE to WNW-ESE is associated to the main basins: Rosas and Bagur. Three main units have been differenciated in the seismic profiles overlying a pre-Neogene basement: the two lowest units (Oligocene?- Lower Miocene and Middle-Upper Miocene units) are associated with the development of neogene deposits, whilst the third consist of post-Messinian deposits (Plio-Quaternary unit). The proposed geodynamic evolution of the area includes two stages: (1) latest Oligocene-Burdigalian rifting where extensión was accomodated by NE-SW normal faults and NW-SE transfer faults related to the Burdigalian drifting, (2) Tortonian to Present stage characterized by the blocking of the NE-SW faults and the extensional development of the NW-SE fault trend. Each stage involves a basin geometry and a style of faulting

Seismic and tectonic interpretation of the ESCI-Béticas and ESCI-Alborán deep seismic reflection profiles: structure of the crust and geodynamic implications

The seismic and tectonic interpretation of the ESCI-Béticas and ESCI-Alborán deep seismic reflection profiles provides an overall image of the crust on the northern flank of the Betic-Rif orogenic system. In these interpretations, previous wide-angle refraction-reflection and MCS industrial profiles were used in order to identify the sequence of collisional-extensional events that built up the crust in this escape-type orogenic area. A model of convergence between the Iberian crust and the Alborán domain, including coeval extension due to lateral escape, is consistent with the data presented in this paper

Historical palaeohydrology and landscape resilience of a Mediterranean rambla (Castellon, NE Spain): Floods and people.

This paper provides a new methodological approach to analyse secular patterns of flooding (magnitude and frequency) from sedimentary evidence (palaeofloods), taking into account changes in channel geometry, and their links to historical environmental changes and the inherent social and demographic evolution within the catchment. A case study analysis was focused in Rambla de la Viuda (drainage area of 1500 km2) whose stream flow is related to extreme rainfalls. A 500 years sedimentary archive was reconstructed from eight stratigraphic profiles comprising continuous sequences of slackwater flood deposits interbedded with episodic colluvial and edaphic horizons. Discharge estimates associated to sedimentary flood evidences were obtained from one-dimensional hydraulic modelling. The stratigraphic units were sampled to characterise their geochemical and paleobotanical (phytoliths) contents. Palaeoflood chronology was obtained from radiocarbon and luminescence (OSL) dating, supported by documentary data (written historical documents). A high frequency and high magnitude palaeoflood period took place during the 15th-middle 16th century, which seem to correlate in time with general wetter conditions. Three short-term environment stability conditions (land use and climatic) also made possible the development of three paleosols. The lowest flood magnitude and discharges in the sedimentary record was found between the mid-17th to mid-18th centuries, under prevailing drier environmental conditions. Episodic high magnitude flooding took place at late 18th century, correlating in time with palaeovegetation and geochemical evidences of important changes on land use (deforestation and grazing). Poorer developed soils were found at upper stratigraphic sequences (19th century) characterised by thick units of colluvium deposits, usually culminating sequences of short-lived continuous slackwater flood units. Despite of the potential human influence (land-use) on soil hydrology, the longterm behaviour of high magnitude floods (>1000 m3 s-1) has been stationary over the last 500 years

Factors controlling rare earth element plus yttrium enrichment in Fe–Mn crusts from Canary Islands Seamounts (NE Central Atlantic)

Marine minerals are important because concentrate in their structure high contents of strategic and critical elements as rare earth elements. Forty-two samples from eight seamounts of Canary Islands Seamount Province (CISP) have been analyzed in order to evaluate their rare earth elements plus yttrium contents (REY). Highest contents of REY are related to hydrogenetic minerals and essentially Fe-vernadite (on average 3000 μg/g). Diagenetic minerals, on the other hand, show the lowest REY contents with an average content of 260 μg/g. These differences also depend on the growth rates, hydrogenetic minerals with growth rates between 0.5 and 5 mm/Ma allow the incorporation of more REY in their structure. REY contents in studied samples varies depending several factors associated with depth and location, shallowest samples presumably growth near or within the oxygen minimum zone are the most enriched with up to 3800 μg/g due to local enrichment of these elements and the slowest growth rate promoted by the reduced ambient conditions while deeper samples around 3000 m water depth show 2800 μg/g. Location also has a role in REY contents essentially due to the presence of different currents. Samples faced to north are exposed to the more oxygenated waters of the North Atlantic Deep Water and are depleted in REY if compared with deeper samples facing to south to the more oxic Antarctic Bottom Water. Finally, the case of study made on three different seamounts of the CISP show that Fe–Mn crusts from this area could provide on average 130 tons of hydrometallurgical recovered REY (based on 1 km2 areal crust coverage) together with interesting quantity of several other strategic and base elements as Mn, Co, Ni, Cu, V, Mo between others

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

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

Seismic architecture of mud volcano systems in the Ceuta

Analysis of a new dataset of high-resolution seismic and swath bathymetry data acquired during the CONTOURIBER-1 cruise in the Ceuta Contourite Depositional System (Western Alborán Sea), reveals the detailed architecture of several mud volcanoes systems that comprises both surface and buried constructional edifices as well as their subsurface feeder complex which pierces the contourite deposits. Seismic characterization, distribution and interpretation of structural elements associated to the mud volcano system promotes a more comprehensive understanding of the processes involved in their genesis and evolution.El análisis de los datos batimétricos y de sísmica de alta resolución durante la campaña CONTOURIBER-1 en el Sistema Deposicional Contornítico de Ceuta (Mar de Alborán occidental) muestran la arquitectura en detalle de varios sistemas de volcanes de fango que comprenden edificios en el fondo marino y edificios enterrados, así como sus complejos de alimentación a través de los depósitos contorníticos. La caracterización sísmica, distribución e interpretación de estos elementos estructurales que componen el sistema de volcán de fango constituyen una importante ayuda para un mejor y mayor conocimiento de su génesis y evolución.Publicado

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

Características morfológicas y estructura superficial de montículos submarinos del talud inferior del margen continental canario (O de las Islas Canarias)

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