Дисертації з теми "Sédiments (géologie) – Transport – Méditerranée (mer)"
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Higueras, Marina. "Impact of eastern storm on the transfert of particulate organic matter in the Gulf of Lion (NW Mediterranean sea)." Perpignan, 2014. http://www.theses.fr/2014PERP1240.
Rivers represent the primary pathway for particulate organic matter (POM) transport from continent to the continental shelf and are capable of discharging significant amounts of this organic matter during the occurrence of short but violent flash flood events, commonly associated with eastern storms. Terrestrial matter delivered by rivers during flash flood events is stored into continental shelf. Then, hydrodynamic conditions occurring at the shelf are capable of transferring this matter to the deep sea along submarine canyons. This study has allowed to simultaneously assess the variations of the quantity and origin of the POM in several rivers discharging into the NW Mediterranean Sea during a flash flood event, in the settling particles of two sediment traps deployed into the southern flank of the Cap de Creus canyon; and in the surficial sediments along 4 transects perpendicular to the continental shelf during March 2011. The obtained results will help us to understand land-sea exchanges
Gervais, Anne. "Analyse multi-échelles de la morphologie, de la géométrie et de l'architecture d'un système turbiditique sableux profond (Système du Golo, Marge est-Corse, Mer Méditerranée) : implications pour la reconnaissance des processus de transport et de dépôt des sédiments et pour la construction des lobes sableux en domaine profond." Bordeaux 1, 2002. http://www.theses.fr/2002BOR12621.
Meslard, Florian. "Apports sableux par les fleuves côtiers méditerranéens et aléa de submersion marine (ASPLEC)." Electronic Thesis or Diss., Perpignan, 2023. http://www.theses.fr/2023PERP0053.
Obtaining accurate estimates of sediment budgets on the land-sea continuum and understanding how these budgets affect coastal dynamics has become a crucial issue in the current context of rising sea levels and retreating coastlines. The torrential nature of mediterranean coastal rivers, linked to intense meteorological events, is characterized by brief but violent flooding episodes, during which most of the water and sediment discharge is delivered to the coastal zone in a few days. This episodic behavior of operation also has an impact on their river outlet as well, which can become obstructed by the development of sandy spits, leading to heavy flooding in coastal areas during concomitant storm and flood events. The aim of this thesis is to improve our understanding of intermittent river mouths processes, and to assess their interaction with the sediment transport in a land-sea continuum. A multi-scales (land-sea) spatio-temporal approach combining morphological, hydro-meteorological and sediment transport monitoring data was applied to the Têt River, an example of a mediterranean coastal river. The results provided with 1) a better understanding of the mechanisms at this intermittent river mouth system governed by auto-allocyclic and anthropogenic processes, 2) an improved estimates of suspended solids fluxes, provided by the first estimates of suspended and near-bottom sand fluxes, as well as understanding the role of morphology on their transfer to the coastal zone, and 3) an improved understanding of concomitant storm and flood events on the dynamics of the morphological response and the associated sediment transport
Payo, Payo Marta. "Modélisation du transport sédimentaire et des interactions morphodynamiques par les courants de turbidité dans les canyons sous-marins. Application à la Méditerranée Occidentale." Thesis, Brest, 2016. http://www.theses.fr/2016BRES0117/document.
Turbidity currents in submarine canyons are the main contribution for sediment transfer across the continental margins. Geological studies of submarine canyons and associated turbiditic systems for more than 30 years led to an extraordinary breakthrough in the understanding of how turbidite systems evolve. However, these studies remain limited to a posteriori interpretations, based on the distribution of deposits and morphological evidences. The overarching aim of this thesis is to apply a 2DH process-based model to simulate large-scale turbidity currents on two different submarine canyons in the western Mediterranean coast.The work in La Fonera canyon, in the Catalan margin, focuses on the modelling of sediment transport and accumulation resulting from trawling activities on the canyon flanks. The numerical process-based provides a 3D visualization of potential trawling impacts on sediment dynamics. The study represents a starting point for the assessment of the sedimentary impact of bottom trawling in deep continental margins. The present work can help in the identification of trawling areas with lesser impacts. The Var Sedimentary System, located in the vicinity of Nice (France), is connected to the Var River during both low and high-stands and it can be considered as a natural laboratory for the study of the climatic control on the turbiditic activity. The influence of Coriolis forces on the spatial evolution of the hyperpycnal flows and hence in the construction of the Var Sedimentary Ridge (VSR) is evidenced and supported for the first time.The major drawback is the limited amount of information for the necessary initial and boundary conditions; hence modelling results might not be of predictive quality. However, modelling results provide a full-scale vision of the system allowing the identification of sediment pathways and deposition areas on the basis of physical processes and enlarge the present knowledge of the canyons studied. The results obtained may help in the identification of strategic mooring and coring sites to further advance the state of our knowledge on sediment dynamics of the different cases studies
Reynaud, Jean-Yves. "Architecture et évolution d'un banc sableux de mer celtique méridionale." Lille 1, 1996. http://www.theses.fr/1996LIL10199.
Miralles, Jérôme. "Etude couplée des radionucléides isotopes stables du plomb en Méditerranée occidentale." Aix-Marseille 3, 2004. http://www.theses.fr/2004AIX30008.
The aim of this work is to identified an environmental deposit able to have stored the atmospheric signal over large time-scale leaning our investigations on lead stable isotopes (206Pb, 207Pb, 208Pb) and radionuclide (210Pb, 137Cs, 239Pu, 240Pu) analysis. Owing to prior studies on anthropogenic lead sources, emission intensity and sedimentary accumulation, we choose to investigate the marine sediments of the Western Mediterranean. In the Gulf of Lions, the sedimentary accumulation is 101±17 [micro]g. Cm-2 high in good agreement with the atmospheric inventory estimate we made from saltmarshes of Camargue (105±11 g. Cm-2). The reconstructed lead accumulation through a modelling step coupling 210Pb and stable isotopes corroborates the regional anthropogenic emissions (Ferrand, 1996). Briefly, in this context of the marine sediments are a relevant proxy to study past lead atmospheric concentration over the last hundred years. In the Alboran Sea, the study area is less constrained and more complex in terms of climatic meteorological and hydrological conditions. The sedimentary inventory is of 153±47 [micro]g. Cm-2, 1,5 higher than in the margin sediments of the Gulf of Lions. The analysis of aerosols, sediments and settling particles evidences a continuity between the atmospheric signal and the sedimentary record. In spite of this encouraging results, the knowledge of the Alboran system is still too restricted in order to unambiguously conclude on accuracy of deep marine sediments of this area to study past atmospheric fallouts
Ducassou, Emmanuelle. "Évolution du système turbiditique profond du Nil au cours du Quaternaire récent." Bordeaux 1, 2006. http://www.theses.fr/2006BOR13263.
Blanpain, Olivier. "Dynamique sédimentaire multiclasse : de l'étude des processus à la modélisation en Manche." Rouen, 2009. http://www.theses.fr/2009ROUES036.
The purpose of this work is the implementation of a sediment transport model in the English Channel. The design of such a model requires the identification of the physical processes, their modelling and their in-situ validation. Because of the sedimentary particularities of the study area, modelling of the mechanical behaviour of a non uniform mixture of sediments and particularly of the fine grains within a coarse matrix is required. This study focused on the characterization of the relevant processes by acquisition of experimental and in-situ data. Data acquired in hydro-sedimentary conditions comparable to those found in the English Channel are scarce. A new instrument and image processing technique were specifically conceived and implemented in-situ to observe and measure, with a high temporal resolution, the dynamics of a strongly heterogeneous mixture of particles in a grain-size scale. The data collected compared well with several existing formulations. One of these formulations was chosen to be adapted. The transfer dynamics of fine grains in coarse sediments and their depth of penetration were acquired from stratigraphic samples. The sediment transport model deals with multisize grains and multi sedimentary layers, it is forced by swell and currents, and accounts for beadload and suspended load transports. It was applied to realistic scenarios for the English Channel
Accornero, Alessandra. "Exportation de matière biogène dans la Mer de Ross : implications pour le cycle du carbone." Perpignan, 2005. http://www.theses.fr/2003PERP0671.
The researches conducted in the framework of this thesis allowed to describe, on yearly and interannual time scales, the transfers of materials from the surface water column to the sediments of the Ross Sea. On the basis of the observations carried out on sediment trap samples, the annual biogeochemical dynamics of the system, the temporal relationships between productivity and sedimentation yearly cycles, the role of dominant zooplankters as contributors to carbon fluxes were clarified. We identified the relations among phytoplankton succession, affected by hydrology, changes in composition of the superficial particulate stocks, and the tendency of suspended matter to sink, by following the evolution of the plankton community throughout the austral summer. The annual cycle of primary productivity, the succession of different phytoplankton assemblages and the predominance of different feeding modes are the factors that globally control particulate transport to sediments. Besides these aspects, which are characterized by a relatively recurrent annual trend, other factors, abiotic and largely unforeseeable, appear to play an important role. On a time scale of months, the vertical displacement of isopycnal surfaces can hinder sedimentation, while on a longer time scale currents determine, through advection, the decoupling of fluxes in the surface and deep layers
Radakovitch, Olivier. "Etude du transfert et du dépôt du matériel particulaire par le 210 Po et le 210 Pb : application aux marges continentales du Golfe de Gascogne (NE Atlantique) et du Golfe de Lion (NW Méditerranée) par Olivier Radakovitch." Perpignan, 1995. http://www.theses.fr/1995PERP0212.
Hemdane, Yacine. "Dynamique hydro-sédimentaire de l'avant-côte de type macrotidal : le cas du littoral du Nord-Pas-de-Calais, France." Littoral, 2006. http://www.theses.fr/2006DUNK0302.
Three field campaigns were carried out in the nearshore zone of the Opal Coast, Southern North Sea, with the aim of improving our understanding of the hydrodynamics and sediment transport patterns prevailing on a macrotidal shoreface subject to significant wind influence. Three field sites, respectively subject to erosion, accretion and stability, were chosen and hydrodynamic conditions (water levels, waves, longshore and cross-shore currents) were monitored at depths ranging from 5 to 10 m together with bed sediment sampling under various wind forcing conditions. Simulation of sediment transport was carried out using the semi-quantitative grain-size vector model of Gao and Collins (1992) and the Sedtrans96 model of Li and Amos (2001). The models of Yalin (1963) and Grant and Madsen (1986) were used to calculate bed shear stress and sediment entrainment. The results highlight an essentially longshore sediment circulation system hinged on the regional bi-directional flood-ebb tidal pattern. Superimposed on this system is a spatially and temporally variable asymmetry pattern due to wind and wind-wave forcing and to the local bathymetry which is dominated by a complex system of tidal banks and ridges. The local bathymetry probably induces resonance phenomena that affect the tidal wave and tidal ellipse vectors. Cross-shore sediment transport processes only occur during tidal reversal phases, when negligible tidal current velocities give way to wind-forced currents and wave action favourable to onshore transport, qith offshore transport induced by bed return flows and infragravity waves (between 0,03 and 0,003 Hz). However, the obliquity of the major axis of the tidal ellipse relative to shoreline orientation may also generate cross-shore flows across the shoreface. It is important to note that the strong longshore tidal currents, sometimes reinforced by wind forcing, may annul cross-shore sediment transport. This is highlighted by the longshore morphology of the shoreface tidal ridges which appear to be subject to little onshore movement
Minster, Gaspard. "Modélisation du processus de saltation en milieu extrême : application au Raz Blanchard." Thesis, Brest, École nationale supérieure de techniques avancées Bretagne, 2019. http://www.theses.fr/2019ENTA0006.
Understanding the mechanism of saltation in areas of high tidal currents such the Alderney Race, is needed to develop exploitation of hydrokinetics energy. In these areas, sediment transport is characterized by inertial regime. An experimental study in a channel and a numerical simulation are used. The principle consists to let spherical particles roll in different flows on a defined bed roughness. After having characterized the flow, we recorde the particles movement with a Fastcam in order to identify height and length of jumps, impact and rebound velocity and angle. A first law between relative roughness and length/height ratio is established, as well as a second law linking the Shields parameter and the height of the jumps. It is then possible, with the knowledge of theShields parameter, the bed roughness and the diameter of the sediments, to predict the mean jumps height and length. The experimental results are in agreement with the laws described in the literature, and complete them for the inertial regime. These proposed laws are then compared and completed by a numerical model of periodical saltation (Berzi et al. 2016). Finally, they are applied on the study area of the Alderney Race to carry out simple maps. These maps characterize the jumps in different places of the Alderney Race
Yu, Zhaojie. "Quaternary Indian and East Asian monsoon reconstructions and their impacts on weathering and sediment transport to the ocean." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS189.
The main objective of this PhD study is to reconstruct the evolution of the Asian monsoons during the Quaternary and their impacts on the continental erosion and sedimentary transfers from land to sea by the investigation of sediments cores collected in the Northern Bay of Bengal, the western Philippines Sea and the Arabian Sea. The implemented scientific strategy involves mineralogical (clay size fraction), sedimentological (grain-size laser) and geochemical (⁸⁷Sr/⁸⁶Sr and εNd) analyses in order to establish sedimentary sources, conditions of erosion and transfer of sediments to the Ocean. The analyses of the concentration of Rare Earth Elements (REE) and εNd were also made on seawater and foraminifera samples to better constrain the εNd as a proxy of weathering in a context of strong seasonal variations of sediment discharges by Himalayan rivers. Clay mineralogy and laser grain-size analyses have been conducted on sediments from core MD06-3050 collected on the Benham Rise (Philippines Sea). Siliciclastic grain-size results indicate variations of the relative proportion of three grain-size sub-populations corresponding to eolian dusts (EM2 about 9-11 μm) and Luzon rivers inputs (EM1 about 2-5 μm and EM3 about 19-25 μm). The long-term evolutions of the EM1/EM2 and smectite/(illite+chlorite) ratios permit to reconstruct variations of the contribution of detrital material deriving from the volcanic arc of Luzon and rainfall intensity of this tropical region. At long time scale, periods of intensification of monsoon rainfall on Luzon are associated to a reduction of precipitation on central China. These periods are also associated to an increase of the zonal gradient of sea surface temperatures on the equatorial Pacific Ocean suggesting a strengthening of El Niña conditions. These results highlight for the first time a strong role of the dynamics of the meridian circulation of ENSO on the long-term changes of rainfall of the tropical western Pacific during the Quaternary. In the Arabian Sea, clay mineralogy, siliciclastic grain-size, ⁸⁷Sr/⁸⁶Sr ratio and εNd were analysed on Quaternary sediments of the IODP site U1457. Our results suggest a change in the relative proportions of sediments from the Deccan Trapps (smectite) and the Indus river (mainly illite and chlorite). Variability of sedimentary sources and sediment transport (turbidites activity) to the Indus Fan have been reconstructed and attributed to monsoon rainfall and the sea level variations. The concentrations of REE combined with εNd were analysed on seawater samples collected in June 2012 along a North-South cross section in the Bay of Bengal. We highlighted from normalized REE patterns that the contributions of dissolved REE from the Ganges-Brahmaputra river system was the main source of the dissolved REE of surface waters of the Bay of Bengal, whereas the desorption of lithogenic particles dominate the dissolved REE of the intermediate and deep waters masses. We then revalued the residence time of the dissolved REE in the Bay of Bengal. A comparison of εNd, obtained just before the increase of the Ganges-Brahmaputra river discharge inferred by Indian monsoon rainfall, with the results obtained by Singh and al. (2012) for seawater samples collected after the peak of river discharge, allowed us to highlight for the first time a seasonal variability of seawater εNd of the Bay of Bengal. εNd have been analysed on planktonic foraminiferas of core MD77-176 located at 1375 m water depth to reconstruct for the first time the seawater εNd record of the intermediate waters masses of northern Bay of Bengal for the last 27 kyr. This new seawater εNd record of the Northern Bay of Bengal give us new constrain for this proxy already used to reconstruct past changes of the Himalayan weathering
Montero, Serrano Jean Carlos. "Sedimentary and paleoclimate dynamics of the Gulf of Mexico during the last glacial cycle." Thesis, Lille 1, 2009. http://www.theses.fr/2009LIL10059/document.
The objectives of this thesis are to study the sedimentary features of some basins of the Gulf of Mexico (Pigmy and La Salle basins) in order to reconstitute the variability of the detrital input via the Mississippi River during the last climatic cycle. An integrated approach coupling mineralogy, granulometry, and geochemistry (inorganic and organic), within a precise chronostratigraphic framework, allows to progress in the understanding of the relations between the mid- and high-latitude climatic mechanisms and the subtropical hydrology, as well as to propose synoptic models of the ocean-atmosphere coupling. The contrasting mineralogy of the zones drained by the catchment system of the Mississippi River watershed allows constraining the continental zones which will successively feed the sedimentation of the Gulf of Mexico. The modifications of the detrital sources revealed for the last climatic cycle enabled (1) to track down the localization of the zones of destabilization of the southern margin of the Laurentide Ice Sheet and the sequence of sedimentary processes during the freshwater discharges, which characterized the last deglaciation, (2) to highlight modifications of the precipitation front which were associated with episodes of large Mississippi River floods during interglacial times, and therefore, to deduce information on the hydrological regime, and (3) to suggest schematic models of meridian transfer of moisture contrasted during interglacial stages 1 and 5e, suggesting an appreciable difference in the atmospheric configurations. The confrontation of these results with other paleoclimatic records allowed to propose simple models of the atmosphere-ocean-continent interactions recorded in the Gulf of Mexico, which are based on the modifications of both the atmospheric configurations (Jet Stream and ITCZ) and oceanic (extension of Atlantic Warm Pool). These models confirm the major role of the atmosphere as a vector of rapid climatic variability
Lafosse, Manfred. "Distribution et enregistrement de la déformation en contexte de convergence oblique : évolution géodynamique de la marge marocaine du bassin d’Alboran au Plio-Quaternaire." Electronic Thesis or Diss., Paris 6, 2017. http://www.theses.fr/2017PA066651.
The oblique convergence of the tectonic plates with respect to the continental margins leads to the distribution of the deformation between raised zones and subsidence zones. In this context, vertical movements can be controlled by the structural inheritance and can influence the architecture of the sedimentary deposits of the continental shelf and the deep basin. Seismic reflection profiles and high resolution bathymetry allow to image the continental shelf and the deep basin. In the western Mediterranean, the African-Eurasian convergence and the back-arc context have controlled the deformation of the Alboran domain since the Miocene. The oblique convergence led to the formation of large transpressive structures crossing the Alboran basin and Miocene strike-slips faults reusing locally the boundaries of the thrust sheet set up during the Oligo-Miocene collision. Three aspects are developed in this thesis: 1) the characterization of the Pleistocene tectonic structures associated with the Nekor basin, a peripheral basin of the Alboran domain situated on its southern margin, with an emphasis on the importance of the alpine inheritance in the evolution of this basin, 2) the decoding of the architecture of the Nekor basin sedimentary platform, to propose an age model of deposited sequences for the last 500 000 years, demonstrating the influence of the tectonic segmentation of the margin on the geometry of the sedimentary platform, 3) the history of the evolution of folds and faults affecting the deep basin from the Pliocene and the chronology of the tectonic structures from the Messinian Salinity Crisis to present-day
Beny, François. "High resolution study of the deep-water Southern Ocean circulation during the last climatic cycle using geochemical and mineralogical proxies in marine sediments : implication for the CO2 cycle." Thesis, Lille 1, 2020. http://www.theses.fr/2020LIL1R031.
This PhD thesis provides new insights into both the deep Southern Ocean circulation and CO2 cycle based on geochemical, radiogenic isotopes and clay mineralogical signatures of the terrigenous fractions transported by the main deep-water masses using sediment cores recovered in the South Atlantic sector (core MD07-3076Q, central South Atlantic) and in the South Indian sector (core MD12-3396Q) of the Southern Ocean.A careful preliminary study of the geological properties of the potential sediments sources to the Southern Ocean and of the source-to-sink transportation patterns of detrital particles was crucial to develop a well constrained provenance study in this rather complex area. These preliminary data demonstrated that it was absolutely necessary to work on distinct grain-size fractions in the South Atlantic Ocean in order to efficiently track different water masses. Such an approach successfully permits: (1) provenance identification of the various grain-size fractions (clay, cohesive silt and sortable silt); (2) an assignment of each grain-size fraction to a specific water-mass; (3) the reconstruction of the main deep water-mass pathways past changes, (4) to reconstruct paleoenvironmental changes over South America during the Holocene.Overall, our data support the conclusions drawn using other proxies: Strong southern deep-water masses (i.e. AntArctic Bottom Water, AABW, and Circumpolar Deep Water, CDW) and weak southern North Atlantic deep-water (NADW) prevailed during the last glacial period. The transition from this glacial state to the modern period likely happened during the Bølling Allerød (B/A) with: (1) a southward migration and a deepening of the NADW into the South Atlantic sector of the Southern Ocean, (2) a retreat to the South and a slowdown of the southern deep-water masses.In addition, this study successfully permits the distinction between the AABW and the ACC (that includes CDW) in both sectors of the Southern Ocean. This enabled the quantification of the relative contribution to sedimentation of all the main deep-water masses in each sector (i.e. AABW, CDW and NADW in the South Atlantic sector; ACC and AABW in the South Indian sector). Thanks to this distinction, it was possible to provide evidences of previously unknown AABW activities through time, and to study the dynamical interactions between the AABW and the LCDW in the South Atlantic sector of the Southern Ocean. We show that Heinrich Events (HE) 1, 2 and 3 are preceded by a modification of the Southern Ocean overturning circulation, and especially associated to a significant increase in AABW contribution to sediment deposition. Consequently, this work highlights that a change in the Southern Ocean overturning circulation can play a major role or even trigger the Heinrich Events. Our data also indicates that the turbulent mixing was stronger during HE 2 than during HE 1, even though HE 2 is muted in atmospheric CO2 records. This suggests that the exchanges between the deep ocean and the atmosphere might have been disabled due to dynamical/physical barrier resulting from background conditions involved by low obliquity during the last glacial period. At the very end of this glacial period, our data indicate a substantial “pulse” of AABW speed and northern extent in the South Atlantic sector of the Southern Ocean. This "pulse" is concomitant with the first increase of the ventilation recorded in the same sediment core and ends with the beginning of the HS 1, a period of rising atmospheric CO2. These observations suggest that this rapid incursion of AABW into the South Atlantic Ocean may be responsible of the breakdown of the physical/dynamical barrier between the deep CO2-rich ocean and the surface, enabling the exchange between these CO2-rich waters and the atmosphere during the HS 1, and thus, the rise of atmospheric CO2 during the last deglaciation
Asia, Laurence. "Analyse des hydrocarbures dans des sédiments superficiels de zones côtières Méditerranéennes (Golfe de Fos, Rade de Marseille et Massif des Calanques)." Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4352.
The first part of this work concerns the origin, the nature and the distribution of hydrocarbons present in the coastal surface sediments located between the delta of the Rhone and Cassis harbor. Total hydrocarbons levels ranged from 10 mg.kg-1 to 260 mg.kg-1 sed dry weight. Only station 21 (Cortiou outfall sewer) has a very high hydrocarbon content (1067 dry mg.kg-1 sed. dry weight) compared to the other stations. Origins of hydrocarbons in surficial sediments are multiple : biogenic (terrestrial inputs, marine organisms), anthropogenic (petroleum contamination) and pyrolytic (residues of natural or anthropogenic combustions) The second part of the work deals with a study of the fate of oil in infralittoral coastal sediments. A field experimentation of artificial contamination has been conducted by 20 m of depth. We studied the evolution of hydrocarbons during a 1220 days period using PVC cores with or without a massive addition of crude Arabian Light oil (20 g.kg-1 sed wet.).The results of this study show clearly an important disappearance of saturated hydrocarbons after 1220 days with a preferential disappearance of n-alkanes compared to branched alkanes. This evolution is very well marked in the surface sediments (0-4 cm) but also, at a least degree, in the deeper sediments (8-10 cm). Our results are in good agreement with those related to the evolution of hydrocarbons in highly contaminated sediments by oil spills such as the Amoco-Cadiz in 1978 on the Brittany coasts or the Exxon Valdez in 1989 on the Alaska coasts
Sionneau, Thomas. "Transferts continent-océan : enregistrement du dernier cycle climatique par les sédiments terrigènes du Golfe du Mexique." Electronic Thesis or Diss., Lille 1, 2008. http://www.theses.fr/2008LIL10105.
The Gulf of Mexico (GOM) is a key area for the global thermohaline circulation (THC) and for the global-climatic system, since its hydrological characteristics (hlgh salinity and temperature) partly control Gulf Stream physical properties. Dunng the last climatic cycle, GOM hydrology was impacted by episodic freshwater inputs via the Mississippi River resulting from intermittent meltmg of the Laurentide Ice Sheet (LIS). The resulting salinity changes affected the THiC. global heat exchange and worldwide climatie conditions. Direct effeets of these freshwater supplies on the GOM paleoceanography have been documented studying the planktonic foraminifera [delta]18O evolution By contras!. terrigenous inputs associated with these meltwater pulses are poorly understood. These detrital fractions are. however. IIkeiv to provide information on the link between continental and marine records during the last climatic cycle. An overview of the main continental detrtital source areas, of the dominant factors controlling clav minerai transport patterns (by drawing clay minerai distribution maps in the US and northem GOM) and of thin terrigenous particle sedimentation in the GOM (by analogical modeIing), lays the groundwork for the use of clay-minerai assembiages for understanding the connection between North America and the GOM. The downcore investigations of sedimentary (clay mineralogy, grain-slze . .) and isotopic ([delta]18O) records ln two minibasins of the GOM (Orca Basin and Basin 4) allow us to explain the fluvial inputs variations, during the last climatic cycle, by paleoenvironmental (ice meltback) and paleocllmatic (atmospheric circulation) fluctuations that affected North America
Sionneau, Thomas. "Transferts Continent/Océan : Enregistrement du dernier cycle climatique par les sédiments terrigènes du Golfe du Mexique." Phd thesis, Université des Sciences et Technologie de Lille - Lille I, 2008. http://tel.archives-ouvertes.fr/tel-00366377.
Abessolo, Ondoa Grégoire. "Réponse des plages sableuses d'Afrique de l'Ouest, golfe de Guinée, face au forçage multi-échelle." Thesis, Toulouse 3, 2020. http://www.theses.fr/2020TOU30029.
This thesis presents a multi-scale investigation of the role of waves, sea level and human settlements to understand long-term coastal evolution of the 400-km long sandy Bight of Benin coast (Gulf of Guinea, West Africa). Coastal morphology and its ocean drivers are monitored using local shore-based video camera and regional satellite remote sensing. New video developpements show the potential of video camera in sensing daily beach profile, waves and sea level at the coast. The results reveal the dominant influence of waves on shoreline variability at the event (daily) and seasonal scales, whereas at the intraseasonal and interannual scales, the shoreline is dominantly modulated by sea level changes. Over longer periods (decades), anthropogenic influence, such as deep water harbours and the reduction of sediment river (such as Volta and Niger) discharge due to dams significantly alter sediment transport, creating several erosion zones. These observations over the long term are satisfactorily reproduced by the implemented shoreline model, specially in the vicinity of the harbors, and allows to estimate, for example, the amount of sediment nourishment necessary to limit erosion downstream of Lagos harbor. Beside their fundamental interest, these results put strong basis to improve regional coastal policies
Guerin, Thomas. "Modélisation morphodynamique pluri-décennale des côtes dominées par la marée et les vagues." Thesis, La Rochelle, 2016. http://www.theses.fr/2016LAROS002/document.
This work considers the pluri-decadal morphodynamic modeling of sandy coastal environments subjected to tides and waves. A process-based numerical model is used, together with a collection of field data from the LIENSs laboratory (i.e. bathymetric, hydrodynamic, and seismic data). To simulate the morphodynamic of these environments, two main numerical developments have been added to the model : (1) the sediment heterogeneity, and (2) the bed evolution computation following a WENO-based scheme adapted to unstructured grids. The first model application concerns the 40-year hindcast (period 1960 to 2000) of a wide estuary mouth sandbank located in the Marennes-Oléron bay : the Longe de Boyard sandbank. Numerical results suggest that this sandbank long-term evolution is strongly controlled by waves, in spite of its global tide-dominated morphology. Rhythmic nature of sediment accretion, which is observed and modeled in the south part of the bank, was then analyzed from a stratigraphic point of view thanks to the integration of sediment heterogeneity into the model. Grain size rhythmic variations in this area appeared to be related to local wave climate seasonality. The second model application considers the Arçay sandspit evolution (Vendée coast). Morphodynamic results suggest that this sandspit evolution, mainly controlled by waves, is characterized by a combination of both autogenic and external-influenced behaviors
Guillou, Nicolas. "Rôles de l'hétérogénéité des sédiments de fond et des interactions houle-courant sur l'hydrodynamique et la dynamique sédimentaire en zone subtidale - applications en Manche orientale et à la pointe de la Bretagne." Phd thesis, Université de Bretagne occidentale - Brest, 2007. http://tel.archives-ouvertes.fr/tel-00376679.
Cartier, Adrien. "Évaluation des flux sédimentaires sur le littoral du Nord-Pas de Calais : vers une meilleure compréhension de la morphodynamique des plages macrotidales." Phd thesis, Université du Littoral Côte d'Opale, 2011. http://tel.archives-ouvertes.fr/tel-00821126.