Papers by Juan Tomas Vazquez
Marine Geology, 2008
Multibeam bathymetry, high (sleeve airguns) and very high resolution (parametric system-TOPAS-) s... more Multibeam bathymetry, high (sleeve airguns) and very high resolution (parametric system-TOPAS-) seismic records were used to define the morphosedimentary features and investigate the depositional architecture of the Cantabrian continental margin. The outer shelf (down to 180-245 m water depth) displays an intensively eroded seafloor surface that truncates consolidated ancient folded and fractured deposits. Recent deposits are only locally present as lowstand shelf-margin deposits and a transparent drape with bedforms. The continental slope is affected by sedimentary processes that have combined to create the morphosedimentary features seen today. The upper (down to 2000 m water depth) and lower (down to 3700-4600 m water depth) slopes are mostly subject to different types of slope failures, such as slides, mass-transport deposits (a mix of slumping and mass-flows), and turbidity currents. The upper slope is also subject to the action of bottom currents (the Mediterranean Water-MW) that interact with the Le Danois Bank favouring the reworking of the sediment and the sculpting of a contourite system. The continental rise is a bypass region of debris flows and turbidity currents where a complex channel-lobe transition zone (CLTZ) of the Cap Ferret Fan develops. The recent architecture depositional model is complex and results from the remaining structural template and the great variability of interconnected sedimentary systems and processes. This margin can be considered as starved due to the great sediment evacuation over a relatively steep entire depositional profile. Sediment is eroded mostly from the Cantabrian and also the Pyrenees mountains (source) and transported by small stream/river mountains to the sea. It bypasses the continental shelf and when sediment arrives at the slope it is transported through a major submarine drainage system (large submarine valleys and mass-movement processes) down to the continental rise and adjacent Biscay Abyssal Plain (sink). Factors controlling this architecture are tectonism and sediment source/dispersal, which are closely interrelated, whereas sea-level changes and oceanography have played a minor role (on a long-term scale).
El objetivo principal del proyecto VULcanología CAnaria submariNA, VULCANA, es evaluar el grado d... more El objetivo principal del proyecto VULcanología CAnaria submariNA, VULCANA, es evaluar el grado de afección y la recuperación sobre el ecosistema marino del volcán submarino de la isla de El Hierro, haciéndolo extensible a otras regiones canarias de posible interés hidrotermal o vulcanológico. En este sentido, se ha investigado además el volcán de "Enmedio", entre las islas de Gran Canaria y Tenerife. Para ello, se realizará un estudio completo de las propiedades físico-químicas, biológicas y geológicas en las dos áreas descritas (Figura 1).
carga del material de campaña se realizó en el puerto de Cádiz durante los días 16 y 17 de noviem... more carga del material de campaña se realizó en el puerto de Cádiz durante los días 16 y 17 de noviembre del 2016. FECHA FINAL: 24 de noviembre 2016, atraque en el puerto de Cádiz. La descarga del material de campaña y el desembarque del personal científico tuvieron lugar el día 25 de noviembre del 2016. OBSERVACIONES: La realización de esta campaña se ha coordinado con el proyecto del Plan Nacional de I+D+i FAUCES (CTM2015-65461-C2-2-R) "Factores de Riesgo Geológico asociado a cabeceras de cañones submarinos en los márgenes continentales mediterráneos del sur de Iberia" cuyo coordinador es el Dr. David Casas del Instituto Geológico y Minero de España (IGME). Así mismo, los dos últimos días de la campaña se dedicaron a la realización del muestreo de los montículos estudiados por el proyecto MONCARAL (IEO) "Montículos carbonatados Mar de Alborán" del que es Investigadora Principal Dña. María Gómez-Ballesteros (Sede Central del IEO, Madrid).
Multichannel high resolution seismic data acquired during the ERGAP 1 and ERGAP 2 allowed the int... more Multichannel high resolution seismic data acquired during the ERGAP 1 and ERGAP 2 allowed the interpretation of a set of NW-SE to N-S morphological features, mainly ridges, scarps and depressions, recognized in the multibeam data. These features correspond to structures of deformation (faults and folds) that have been developed over the most recent sedimentary units defined in this margin. The Unit 3 has worked as a viscous layer, favouring the upper units deformation and decoupling their deformation from basement structures. The deformation of these units must be considered as the results of a factors addition: i) the presence of viscous layers in the base of postrifts units and ii) the deformation of the margin along Cenozoic Pyrenean compressive phases that has flexured the basement and the margin physiography, generating gravitational gradients, and reactivated basement structures.
The Gulf of Cadiz records the interplay of a variety of sedimentary processes related to the flow... more The Gulf of Cadiz records the interplay of a variety of sedimentary processes related to the flow of the Mediter-ranean Outflow Water (MOW) exiting the Mediterranean Sea, with downslope sedimentary processes and the topography of the region. This work presents detailed morphological features of the Guadalquivir Ridge area, based on high resolution bathymetry and very-high resolution seismic profiles (TOPAS) acquired during the MONTERA cruise. The Guadalquivir Ridge is a SW-NE-oriented relief located on the middle slope of the Gulf of Cadiz (8º-7º10' W). It reaches minimum depths at two highs, one at the Guadalquivir Bank, at the western extreme of the ridge (275 m), and a second one close to the eastern extreme (350 m). The ridge is cut by a gap where the Diego Cao contourite moat is incised forming a narrow, 4-5 km wide, SE-NW oriented channel. It delimits two contourite sheeted drifts (SD) at the northern side of the ridge: the Faro SD at the east (∼ 600 m water depth) and the...
The Gulf of Cadiz records the interplay of a variety of sedimentary processes related to the circ... more 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, semi-circular 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.
Multibeam bathymetry has been used to study in detail the morphology of the Galicia Bank region (... more Multibeam bathymetry has been used to study in detail the morphology of the Galicia Bank region (< 700 m down to 5200 m water depth), in the NW Iberian Margin. Five pshyiographic provinces displaying a complex morphology have been defined. Their geomorphology is characterized by three types of features based on their origin: tectonic, erosive and depositional. Tectonic features are dominant, comprise fault scarps (normal and inverse), seamounts and highs. They condition the general geometry and morphology of the provinces. Erosive and depositional features are mainly related to tectonic features, both their location and genesis. The erosive features comprise slide scars, gullies, channels, and main channels. The valleys eroding the provinces form turbidity systems that drain radially the region of the Galica Bank, transporting the sediment toward the Biscay and Iberian abyssal plains. The depositional features comprise slides and wedges and lobes formed by mass-flow deposits. The...
La zona central de la Cuenca de Alborán se caracteriza por presentar los elementos fisiográficos ... more La zona central de la Cuenca de Alborán se caracteriza por presentar los elementos fisiográficos más importantes de Alborán, como son las dorsales de Alborán y Adra que limitan la depresión del Canal de Alborán. Estos elementos morfoestructurales son el resultado de la convergencia de las placas Africana y Euroasiática. El análisis de datos batimétricos y de perfiles de sísmica con diferentes grados de resolución, ha permitido establecer dos fases de deformación recientes: una de carácter transcurrente de salto normal y otra posterior compresiva que produce una inversión tectónica. Esta última fase sería el resultado de la colisión del Bloque tectónico de la Dorsal de Alborán con el de Adra al consumirse el espacio del curso medio del Canal de Alborán.
The analysis of multibeam bathymetric data and high resolution seismic profiles has allowed us to... more The analysis of multibeam bathymetric data and high resolution seismic profiles has allowed us to define the tectonic geomorphology of the Adra margin, northern Alboran Sea. Four geomorphic tectonic-related structures have been analyzed: (i) Longitudinal ridges (N50-70); (ii) Linear scarps (N30, N55, N130, N165, N-S); (iii) Tectonic depressions (N130, N165, N-S), and (iv) Lines of changes in the slope gradient (N130). In the northwestern sector morphostructure is related to a blind thrust (NE-SW), which folds Quaternary units, and in the eastern sector is linked to the NE-SW sinistral strike slip fault of La Serrata (NE-SW). Between these two structures, a NW-SE dextral strike-slip fault system, including the Adra Fault, and a NNE-SSW highly deformed corridor constituted by secondary NNW-SSE faults have been developed. Minor high angle N-S reverse faults can be related to secondary deformation features, due mainly to the interference of Chella Bank and the regional main fault systems.
A multiple Contourite Depositional System has been defined in the Plio-Quaternary sedimentary reg... more A multiple Contourite Depositional System has been defined in the Plio-Quaternary sedimentary register in the Alboran Sea. This multiple system formed by the Atlantic and the low density and high density Mediterranean Waters, which shaped the margins and basins since the opening of the Gibraltar Strait. Three different (paleo)circulation scenarios are proposed since then: the Atlantic water Flooding;the Pliocene circulation, characterized by immature low and high density Mediterranean waters and a strong countercurrent in the Western Basin; and the Quaternary circulation, characterized by tabular Mediterranean water masses with multiple current dynamics,an increasing influence of density contrasts, and climate shifts causing major vertical and horizontal displacements of their interfaces.
Multidisciplinary work between oceanography, geomorphology and sedimentology has uncovered eviden... more Multidisciplinary work between oceanography, geomorphology and sedimentology has uncovered evidence explaining the uneven development of the turbidite systems (TSs) in the Alboran Sea. Nine TSs have been mapped in the Spanish margin, ranging from sandy to mixed sand-mud fans, and which become sandier towards the Strait of Gibraltar; in contrast TSs do not develop in the Moroccan margin, where three canyons incise the continental slope but there is no TS formation. We interpret that the uneven development of TSs in the two margins and their variable architectures are conditioned by the interaction of alongslope with downslope processes. Two different interaction scenarios with varying intensities are proposed.
ABSTRACT This paper presents the morpho-seismic characterization of Quaternary mass-movement in t... more ABSTRACT This paper presents the morpho-seismic characterization of Quaternary mass-movement in the Almeria margin and eastern Alboran Basin on the basis of the bathymetric and high and very high-resolution seismic data. The mass-movement deposits are located in two sedimentary environments, open slope and morphological highs. The area affected by these deposits varies between 10 km2 and 255 km2. A classification of these mass movements deposits, based on a series of criteria including the causative mechanism, the source area location and physiographic location, is here proposed, differentiating three types of systems: i) attached to platform, ii) attached to slope and iii) detached locally.
ABSTRACT This paper focus on a seismic-stratigraphic and architecture analysis of the Almeria fan... more ABSTRACT This paper focus on a seismic-stratigraphic and architecture analysis of the Almeria fan based on bathymetric data and high and very high resolution seismic data. Two seismic units are defined above the reflector MPR (0.900-0.920 ma) and they consist mainly by six fanlobes and interbedded mass movement deposits. The Pleistocene sedimentary evolution could be explained by two phases. Phase 1 (0900-0440 m.) is aggrading type during which confinement of three fanlobes (6-4) occurred. They present an elongated morphology and similar geometric dimensions. Phase 2 (0.440 ma-present) is a retrograding type during which three fanlobes (3-1) showing lobe/elongate forms and decreased on their geometric dimensions.
Marine Geology, 2008
The high-resolution seismic stratigraphy of the Galicia Bank Region and adjacent deposits of the ... more The high-resolution seismic stratigraphy of the Galicia Bank Region and adjacent deposits of the neighbouring Iberian and Biscay Abyssal Plains was included as part of the geological studies conducted in the area where the oil-tanker Prestige wreck is located. This seismic stratigraphy is characterized by five seismic units (5 to 1, from oldest to youngest) lying above an irregular acoustic basement defined by a highly fractured system of horsts and grabens. These faulted systems have controlled the local depositional architecture, deforming, fracturing, relocating and distributing sediments since the Valanginian. Three depositional models of facies can be recognized on the Galicia Bank Region and surrounding abyssal plains: bank, escarpment, and abyssal plain facies. The bank facies reflects the depositional evolution from initial filling to obliterating stages of the horsts and grabens. The escarpment facies has a local distribution and represents deposition associated with active slopes of the faulted escarpments. The abyssal plain facies represents gravity flow deposits coming mostly from the bounded-fault flanks of the Galicia Bank Region. The Valanginian to Quaternary sedimentary evolution of the Galicia Bank Region reflects depositional responses to tectonic condition. The occurrence of mass-movements confirms that the syn-rift period (Valanginian to Aptian age) along the Galicia margin was diachronous, beginning in the Interior Basin and shifting later toward the west of the Galicia Bank Region (Deep Galicia Margin). The Albian to Quaternary post-rift evolution is characterized by a decrease in tectonic activity and sedimentary variations in the style of deposition (valley and related features, mass-movement deposits, contourites, and drape deposits) conditioned by changes in the sedimentary processes, paleoenvironments, and tectonic reactivation of the regional slopes. The effects of tectonic movements persist, as evidenced in areas where faulted escarpments and highs outcrop, and in areas of nearsurface faulting. The syn-rift and post-rift stages have also conditioned the depositional architecture of the Prestige sinking area. The evolution of the surrounding abyssal plains does not reflect the same pattern to tectonic condition.
Marine Geology, 2008
An analysis of Cenozoic tectonics was carried out on the Galicia Bank Region by means of 750 km o... more An analysis of Cenozoic tectonics was carried out on the Galicia Bank Region by means of 750 km of single-channel and 155 km of multi-channel vertical seismic profiles and multibeam bathymetry. This work forms part of a general study aimed at determining the geological risk in the wreck area of the Prestige oil tanker. Several structures affecting the post-rift sedimentary units were identified: I) Faults inherited from the Lower Cretaceous propagating rift (reactivated and non-reactivated), including reactivated normal (N-S, NW-SE) and transfer (NE-SW) faults; and II) Structures resulting from compressive episodes in the Paleogene to Upper Miocene and the Upper Miocene to the Present, including a) neotectonic normal faults decoupled from the basement structure, b) folds and flexures and c) reverse faults (NE-SW to ENE-SWS) related to the Bay of Biscay subduction, that are the most striking regional structures. The characterization of structural style, sedimentary post-rift unit deformation and morphological trends were used to carry out a detailed study of the morphostructure of the Galicia Bank Region. Six morphostructural provinces were differentiated, from E to W: 1) the Galicia Interior Basin related to a main graben; 2) the Transitional Zone, which is a horst and graben territory; 3) the Galicia Bank Main Horst; 4) the Half-Graben Domain; 5) the Deep Galicia Margin, whose structure shows rotated blocks; and 6) the Northwestern Flank, characterized by reverse faults. The Transitional Zone and the Galicia Bank provinces are assumed to be the two morphostructural provinces of the Galicia Bank marginal platform. The origin of the Cenozoic deformation must have been related to reactivation processes during the Pyrenean orogeny. We propose that the fault pattern observed in the study area is related to the phase of renewed Mesozoic fault activity. Polyphase extension in the rifting stage and Cenozoic movements have produced an extensional interference pattern that is evident in the physiography. The decouplage between basement tectonics and upper sedimentary unit tectonics suggests the presence of a viscous layer. A thrust-related main antiform related to the Bay of Biscay subduction is proposed to explain the origin of the Galicia Bank morphology.
Marine Geophysical Research, 2011
Multibeam bathymetry, high resolution multichannel, and very high resolution single-channel (3.5 ... more Multibeam bathymetry, high resolution multichannel, and very high resolution single-channel (3.5 kHz) seismic records were used to depict the complex geomorphology that defines the Galicia Bank region (Atlantic, NW Iberian Peninsula). This region (&620-5,000 m water depth) is characterized by a great variety of features: structural features (scarps, highs, valleys, fold bulges), fluid dynamics-related features (structural undulations and collapse craters), mass-movement features (gullies, channels, mass-flow deposits, slope-lobe complexes, and masstransport deposits), bottom-current features (moats, furrows, abraded surface, sediment waves, and drifts), (hemi)pelagic features, mixed features (abraded surfaces associated to mixed sediments) and bioconstructions. These features represent architectural elements of four sedimentary systems: slope apron, contouritic, current-controlled (hemi)pelagic, and (hemi)pelagic. These systems are a reflection of different sedimentary processes: downslope (mass transport, mass flows, turbidity flows), alongslope (bottom currents of Mediterranean Outflow Water, Labrador Sea Water, North Atlantic Deep Water, and Lower Deep Water), vertical settling, and the interplay between them. The architectural and sediment dynamic complexities, for their part, are conditioned by the morphostructural complexity of the region, whose structures (exposed scarps and highs) favor multiple submarine sediment sources, affect the type and evolution of the massmovement processes, and interact with different water masses. This region and similar sedimentary environments far from the continental sediment sources, as seamounts, are ideal zones for carrying out submarine source-to-sink studies, and can represent areas subject to hazards, both geologic and oceanographic in origin. Keywords Geomorphology Á Sediment dynamics Á Massmovements Á Contourites and bottom current circulation Á Hemi-pelagic processes Á Galicia Bank volcanism, or by means of biostromes (Roberts 1971;
The development of the Scotia Sea resulted from the plate motions of South America and the Antarc... more The development of the Scotia Sea resulted from the plate motions of South America and the Antarctic Peninsula since the Oligocene. During the SCAN 2001 cruise we investigated a sector of the central and southern Scotia Sea using swath bathymetry, multichannel and high resolution seismic profiles, together with magnetic field measurements. The objectives of our study were to analyze the
Solid Earth Discussions
Progresses in understanding the sedimentary dynamic of the Western Alboran Basin lead us to propo... more Progresses in understanding the sedimentary dynamic of the Western Alboran Basin lead us to propose a model of evolution of its tectonic inversion since the Pliocene to present-time. Extensive and strike-slip structures accommodate the Miocene back-arc extension of the Alboran Basin, but undergo progressive tectonic inversion since the Tortonian. Across the Alboran Basin, the Alboran Ridge becomes a transpressive structure accommodating the shortening. We map its southwestern termination: a Pliocene rhombic structure exhibiting series of folds and thrusts. A younger structure, the Al-Idrissi fault zone (AIF), is Pleistocene to present-day active strike-slip fault zone. This fault zone crosses the Alboran Ridge and connects southward to the transtensive Nekor Basin and the Nekor fault. In the Moroccan shelf and at the edge of a submerged volcano, we date the inception of the local shelf subsidence from the 1.81-1.12 Ma. It marks the propagation of the AIF toward the Nekor Basin. Pliocene thrusts and folds and Quaternary transtension appear at first sight as different tectonic periods but reflects the long-term evolution of a transpressive system. Despite a constant direction of Africa/Eurasia convergence since 5Ma at the scale of the southern margin of Alboran Basin, the Pliocene-Quaternary inversion evolves from transpressive to transtensive on the AIF and the Nekor Basin. This system reflects the expected evolution of the deformation of the Alboran Basin under the indentation of the African lithosphere.
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Papers by Juan Tomas Vazquez