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A new rheological model for thixoelastic materials in subaqueous gravity driven flows ArchiMer
Hermidas, Navid; Silva Jacinto, Ricardo; Eggenhuisen, Joris T.; Luthi, Stefan M..
A new viscoelastic constitutive model for subaqueous clay-rich gravity flows is presented. It is explained that for the materials which exhibit a minimum in their strain controlled flow curves the structure parameter must be a symmetric function of strain rate and stress. Therefore, the destruction of structure within the material is modeled using the dissipation energy. An expression for the elastic strain of the flowing structure is derived. The final set of equations can reproduce the viscosity bifurcation that clay suspensions may exhibit under a given load. This is explained to be important for prediction of the run-out distance of clay-rich gravity flows. The ability of the model to reproduce the general response of pasty materials to step stress and...
Tipo: Text Palavras-chave: Gravity flow; Thixotropy; Clay suspension; Viscosity bifurcation.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00483/59497/62365.pdf
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Benthic foraminiferal response to sedimentary disturbance in the Capbreton canyon (Bay of Biscay, NE Atlantic) ArchiMer
Duros, Pauline; Silva Jacinto, Ricardo; Dennielou, Bernard; Schmidt, S.; Martinez Lamas, Ruth; Gautier, Emeric; Roubi, Angelique; Gayet, Nicolas.
Living (Rose Bengal stained) and dead benthic foraminifera were investigated at 6 deep-sea sites sampled in the Capbreton canyon area (Bay of Biscay, France). Three sites were located along the canyon axis at 301 m, 983 m and 1478 m and 3 stations were positioned on adjacent terraces at 251 m, 894 m and 1454 m. Sedimentary features indicate that frequent sedimentary disturbances of different magnitudes occur along the Capbreton canyon axis and adjacent terraces. Such environmental conditions cause the presence of very particular benthic environments. Along the 6 studied sites, different foraminiferal responses to various sedimentary patterns are observed revealing the complexity of this canyon environment. Some sites (Gitan 3 (canyon axis), Gitan 5 (canyon...
Tipo: Text Palavras-chave: Benthic foraminifera; Capbreton canyon; Habitat disturbance; Turbidite; Submarine canyon.
Ano: 2017 URL: http://archimer.ifremer.fr/doc/00360/47121/47052.pdf
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Different types of sediment gravity flows detected in the Var submarine canyon (northwestern Mediterranean Sea) ArchiMer
Khripounoff, Alexis; Crassous, Philippe; Lo Bue, N.; Dennielou, Bernard; Silva Jacinto, Ricardo.
Current velocities and vertical sediment fluxes in the Var submarine canyon were assessed at three stations respectively at 800 m, 1200 m and 1800 m depth, using moorings deployed for 4 months during winter 2008-2009. During this period, we observed three major sediment gravity flows, all characterized by sudden increases in current velocity that lasted 2-5 h and by downward particle fluxes. Each gravity flow, described using a high frequency current meter and two Acoustic Doppler Current Profiler (75 and 300 kHz ADCP) showed distinctive features. The first event, triggered during a flood of the Var River, was determined to be a hyperpycnal current with a large vertical extent (>100 m high) and relatively low velocity (40 cm s(-1)). The second event,...
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Ano: 2012 URL: http://archimer.ifremer.fr/doc/00113/22394/20343.pdf
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Direct monitoring reveals initiation of turbidity currents from extremely dilute river plumes ArchiMer
Hage, Sophie; Cartigny, Matthieu J.b.; Sumner, Esther J.; Clare, Michael A.; Hughes Clarke, John E.; Talling, Peter J.; Lintern, D. Gwyn; Simmons, Stephen M.; Silva Jacinto, Ricardo; Vellinga, Age J.; Allin, Joshua R.; Azpiroz‐zabala, Maria; Gales, Jenny A.; Hizzett, Jamie L.; Hunt, James E.; Mozzato, Alessandro; Parsons, Daniel R.; Pope, Ed L.; Stacey, Cooper D.; Symons, William O.; Vardy, Mark E.; Watts, Camilla.
Rivers (on land) and turbidity currents (in the ocean) are the most important sediment transport processes on Earth. Yet, how rivers generate turbidity currents as they enter the coastal ocean remains poorly understood. The current paradigm, based on laboratory experiments, is that turbidity currents are triggered when river plumes exceed a threshold sediment concentration of ~1 kg.m‐3. Here we present direct observations of an exceptionally dilute river‐plume, with sediment concentrations one order of magnitude below this threshold (0.07 kg.m‐3), which generated a fast (1.5 m.s‐1), erosive, short‐lived (6 min) turbidity current. However, no turbidity current occurred during subsequent river‐plumes. We infer that turbidity currents are generated when...
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Ano: 2019 URL: https://archimer.ifremer.fr/doc/00514/62594/66952.pdf
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Dragages et environnement marin Etat des connaissances ArchiMer
Alzieu, Claude; Abarnou, Alain; Bassoullet, Philippe; Boutier, Bernard; Chiffoleau, Jean-francois; Crenn, Isabelle; Derrien, Annick; Erard-le Denn, Evelyne; Gourmelon, Michele; Guiliaud, Jean-françois; Silva Jacinto, Ricardo; Le Cann, Pierre; Le Guyader, Françoise; Le Hir, Pierre; L'Yavanc, Jacky; Mauvais, Jean-louis; Menard, Dominique; Michel, Pierre; Monbet, Yves; Pommepuy, Monique; Quiniou, Francoise.
Port activities require continuous or occasional dredging of considerable quantities of sediments : approximately 50 million m3 along the French coastline. A large proportion of the dredgings is authorized for dumping at sea in geographically delimited areas and following an impact evaluation of their potential harmfulness to the marine environment. The environmental risks assessment linked to dredging operations relies on knowledge related to several scientific disciplines contributing to changes in the regulations. This work, intended both for managers and for environmental scientists and engineers, is designed to take stock of the current state-of-the-art in the field of sediment contamination and related ecotoxicological hazards, along with a review of...
Tipo: Text Palavras-chave: Regulations; Management; Impact; Contaminants; Dredging; Réglementation; Gestion; Impact; Contaminants; Dragages.
Ano: 1999 URL: http://archimer.ifremer.fr/doc/1999/rapport-1040.pdf
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Glacial erosion dynamics in a small mountainous watershed (Southern French Alps): A source-to-sink approach ArchiMer
Bonneau, Lucile; Toucanne, Samuel; Bayon, Germain; Jorry, Stephan; Emmanuel, Laurent; Silva Jacinto, Ricardo.
In this study we used major element composition, neodymium isotopes ratios (εNdεNd) and concentration of REE to track and quantify the sediment routing in the Var sedimentary system from source (Southern French Alps) to sink (Ligurian Sea) over the last 50 ka. Our data reveal that changes in sediment sources over that period, associated with concomitant changes in the hyperpycnal (i.e. flood-generated turbidity currents) activity in the Var submarine canyon, were mainly driven by paleoenvironmental conditions in the upper basin and in particular by the presence of glaciers during the last glacial period. Based on this evidence, we determined when and how glacier-derived sediments were produced, then excavated and transferred to the ocean, allowing us to...
Tipo: Text Palavras-chave: Var; Routing system; Glacial erosion; Source-to-sink.
Ano: 2017 URL: http://archimer.ifremer.fr/doc/00358/46957/47130.pdf
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Millennial-Scale Response of a Western Mediterranean River to Late Quaternary Climate Changes: A View from the Deep Sea ArchiMer
Bonneau, Lucile; Jorry, Stephan J.; Toucanne, Samuel; Silva Jacinto, Ricardo; Emmanuel, Laurent.
Although it is widely accepted that erosion and sediment transfer respond to millennial-scale climatic variability, these changes remain difficult to detect in marine sedimentary archives. In the Var sediment-routing system, northwestern Mediterranean Sea, the absence of a continental shelf results in a direct connection between the Var River mouth and the deep basin during both highstand and lowstand conditions. This makes the Var sediment-routing system an ideal target to test whether rivers can transmit climate-driven high-frequency changes in sediment flux to the ocean. On the basis of an unprecedented (centennial-to-millennial-scale) resolution in turbidite sequences, we reconstructed the activity of turbidity current overflows along the deep-sea Var...
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Ano: 2014 URL: http://archimer.ifremer.fr/doc/00248/35925/34447.pdf
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Numerical modeling of bottom trawling-induced sediment transport and accumulation in La Fonera submarine canyon, northwestern Mediterranean Sea ArchiMer
Payo-payo, Marta; Silva Jacinto, Ricardo; Lastras, G.; Rabineau, Marina; Puig, P.; Martin, J.; Canals, M.; Sultan, Nabil.
Bottom trawling leads to recurrent sediment resuspension events over fishing grounds. Recent studies have shown how bottom trawling can drive seascape reshaping at large spatial scales and enhance sediment transport in submarine canyons, which subsequently impacts deep-sea ecosystems. Present knowledge on the transfer and accumulation of sediment flows triggered by bottom trawling is based on localized and infrequent measurements whilst a more complete picture of the process is needed. The present work focuses on the modeling of sediment transport and accumulation resulting from trawling activities in La Fonera submarine canyon, northwestern Mediterranean Sea, thus contributing to an improved assessment of trawling impacts. Based on mooring data within a...
Tipo: Text Palavras-chave: Bottom trawling; Inverse model; Modeling; Sediment transport; Submarine canyon; Turbidity currents.
Ano: 2017 URL: http://archimer.ifremer.fr/doc/00374/48549/48862.pdf
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Paleo-depths reconstruction of the last 550,000 years based on the transfer function on recent and Quaternary benthic foraminifers of the East Corsica margin ArchiMer
Minto'O, Charlie Morelle Angue; Silva Jacinto, Ricardo; Bassetti, Maria-angela; Jouet, Gwenael.
In this study, the model H(i) = 109.6103 + C1 × F1(i) + C2 × F2(i) + … + C33 × F33(i) obtained from depth modelling based on 33 recent benthic foraminifer species distribution, has been applied to the fossil benthic foraminifers from the borehole GDEC-4-2 drilled at a water depth of 491 m, in the East-Corsica basin, covering the last 550,000 years. The obtained variations of the paleo-depths show a medium correlation with the oscillations of the relative sea level and also with the fluctuations of the oxygen isotopic ratio (δ18O G. bulloides and δ18O C. pachyderma–C. wuellerstorfi). This newly developed transfer function is accompanied by an error margin of ± 86 m, suggesting that this model will probably be more suitable for a time scale of the order of a...
Tipo: Text Palavras-chave: Benthic foraminifers; East-Corsica basin; Paleo-depths; Transfer function.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00463/57477/64237.pdf
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Réalisation d'un modèle de dispersion d'un rejet de dragage et des contaminants associés. Rapport définitif: contrat « LITEAU » 2ème phase ArchiMer
Alzieu, Claude; Andral, Bruno; Bassoullet, Philippe; Boutier, Bernard; Gonzalez, Jean-louis; Huet, Martial; Jestin, Herve; L'Yavanc, Jacky; Michel, Pierre; Paulet, Yves-marie; Quiniou, Francoise; Silva Jacinto, Ricardo.
Le projet à pour but de modéliser la dispersion des immersions des boues de dragage, à partir de modèles numériques de manière à pouvoir évaluer le devenir de la charge particulaire et des contaminants associés. Les résultats des expérimentations en laboratoire montrent, qu'à l'échelle représentative du temps de séjour des particules dans la colonne d'eau du champ proche (quelques heures), on ne constate pas de solubilisation des métaux. La libération de la fraction associée aux eaux interstitielles et les flux à l'interface eau-sédiment (diagenèse précoce) après dépôt des sédiments rejetés, sont les processus qui pourraient être la cause d'un apport important de Cd (ou autre contaminant) dissous dans le milieu. Les hypothèses retenues pour l'élaboration...
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Ano: 2003 URL: http://archimer.ifremer.fr/doc/00075/18621/16172.pdf
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The influence of bottom currents on the Zambezi Valley morphology (Mozambique Channel, SW Indian Ocean): In situ current observations and hydrodynamic modelling ArchiMer
Miramontes, Elda; Penven, Pierrick; Fierens, Ruth; Droz, Laurence; Toucanne, Samuel; Jorry, Stephan; Jouet, Gwenael; Pastor, Lucie; Silva Jacinto, Ricardo; Gaillot, Arnaud; Giraudeau, Jacques; Raisson, François.
Mixed turbidite-contourite systems can be found in oceans where bottom currents and turbidity currents interact. The Zambezi turbidite system, located in the Mozambique Channel (SW Indian Ocean), is one of the largest sedimentary systems in the world in length and area of the related catchments. The oceanic circulation in the Mozambique Channel is intense and complex, dominated by eddies flowing southwards and deep currents flowing northwards along the Mozambican margin. Current measurements obtained from moorings at 3400–4050 m water depth in the Zambezi and Tsiribihina valleys show periods of intense currents at the seafloor with peaks of 40–50 cm s−1 that last up to one month and are not related to turbidity currents. These strong bottom-current events...
Tipo: Text Palavras-chave: Contourite; Turbidity current; Mixed system; Oceanic circulation; Mooring; ADCP; ROMS model; Bedform.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00476/58743/61269.pdf
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Turbiditic levee deposition in response to climate changes: The Var Sedimentary Ridge (Ligurian Sea) ArchiMer
Jorry, Stephan; Jegou, Isabelle; Emmanuel, Laurent; Silva Jacinto, Ricardo; Savoye, Bruno.
The Var turbiditic system located in the Ligurian Sea (SE France) is an intermediate mud/sand-rich system. The particularity of the Var deep-sea fan is its single channel with abrupt bends and its asymmetric and hyper-developed levee on the right hand side: the Var Sedimentary Ridge. Long-term sediment accumulation on the Var Sedimentary Ridge makes this an ideal target for studying the link between onshore climate change and deep-sea turbidite stratigraphy. This paper focuses on the establishment of the first detailed stratigraphy of the levee, which is used to analyze the timing of overbank deposition throughout the last deglaciation. Main results indicate that high variability in turbidite frequencies and deposition rates along the Var Sedimentary Ridge...
Tipo: Text Palavras-chave: Last deglaciation; Overbank deposits; Turbidity currents; Var Sedimentary Ridge; Ligurian Sea.
Ano: 2011 URL: http://archimer.ifremer.fr/doc/00030/14104/11370.pdf
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