Submarine canyons incising the continental shelf and slope are hot spots for topography-internal wave interactions, with elevated dissipation and mixing contributing to regional transport and biological productivity. At two Barkley Canyon sites (the continental slope below the shelf-break, and deep within the canyon), four overlapping years of horizontal velocity time-series data are used to examine the effects of irregular topography on the internal wave field. Mean currents are topographically guided at both sites, and in the canyon there is an inter-annually consistent, periodic (about a week) up-canyon flow (-700 to -900 m) above a near-bottom down-canyon layer. There is elevation of internal wave energy near topography, up to a factor of 10, 130 m above the slope, and up to a factor of 100, 230 m above the canyon bottom. All bands display weak inter-annual variability, but significant seasonality. Sub-diurnal and diurnal flows are presumably sub-inertially trapped along topography, and the diurnal band appears to be forced locally (barotropically). Both sites have high near-inertial energy. At the slope site, near-inertial energy is attenuated with depth, while in the canyon it is amplified near the bottom. Both sites show intermittent near-inertial forcing associated with wind events, downward propagation of high-mode internal waves, and the seasonal mixed-layer depth, though fewer events are observed in the canyon. Free semidiurnal internal tides are focused and reflected near critical shelf-break and canyon floor topography, and appear to experience both local and remote (baroclinic) forcing. The high-frequency internal wave continuum has enhanced energy near bottom at both sites (up to 7 times the open-ocean Garrett-Munk spectrum), and inferred dissipation rates increasing from a background of less than 10^-9 W kg^-1 and reaching 10^-7 W kg^-1 near topography. Dissipation is most strongly correlated with the semidiurnal (M2) constituent at both sites, with secondary contributions from the sub-diurnal (Sub_K1) band on the slope, and the near-inertial (NI) band in the canyon. Power laws for these dependencies are dissipation ~ M2^0.83 + Sub_K1^0.59 at the slope, and dissipation ~ M2^1.47 + NI^0.24 in the canyon. There is evidence in spectra of a near-buoyancy frequency build-up of energy correlated with high-frequency continuum variability, with a power law fit of 'shoulder' power ~ dissipation^0.34 that is independent of site topography. Though some general results are expected from observations at other slope and canyon sites, the greater temporal extent of these data provide a uniquely long-term evaluation of such processes. / Graduate

This study investigated the concentration distributions of polyclic aromatic hydrocarbons (PAHs) in the sediment cores collected from Fang-Liao submarine canyon. Chemical fingerprinting techniques and statistical analysis were applied to delineate the possible sources of the PAHs in deposited sediment core samples. It is noteworthy that all cores were not dated; therefore the deposition age could not estimate from the depth of deposition directly. The average concentrations of polyclic aromatic hydrocarbons (£U51PAHs) were found ranged from 229 to 638 (ng/g dry wt) in the sediment cores in Fang-Liao submarine canyon. In addition, the low molecular weight PAHs (2-3 ring PAHs) were found dominant in the PAH composition pattern of most samples. Total PAH concentrations were significantly correlated with total organic carbon (TOC) in all the sediment cores. Compared with sediment quality guidelines (SQGs), the PAH concentrations of all sediment samples were lower than those outlined in the criteria, that suggests no evident adverse biological effects caused by PAHs. Results also showed that total PAH concentration of surface sediments (0-2 cm) decreased with the water depth. Identification of PAHs sources suggests that all up-cores were dominated by petrogenic sources, but all down-cores except for S17 and S18 were dominated by pyrogenic sources or mixed sources. In contrast, biogenic sources were found dominant in S17 and S18 as they were characterized by higher ratio of perylene/£Upenta-PAHs(%). Compared with literature, the sediment cores of Fang-Liao submarine canyon were moderately polluted with PAHs. Analysis of diagnostic ratios and hierarchical cluster analysis (HCA) as well as principal component analysis (PCA) all indicate PAHs sources of Fang-Liao submarine canyon were mainly from petroleum and petroleum combustion sources for site of S3,S5,S7,S8 and S17; while pyrogenic or mixed sources for site of S1,S2,S9,S18 and S33.

Here we investigate sedimentological responses to past climate change in shallow to deep marine depositional environments. Our primary study spans from the Late Pliocene to the Pleistocene (3.3 to 0.7 Ma), and features results from two International Ocean Discovery Program (IODP) Sites U1525 and U1524. Each of these sites is discussed in separate chapters here (Chapters 1 and 2). This interval experienced the change from the warming of the Late Pliocene, known as the Mid-Piacenzian Warming Period, to the Pleistocene cooling. This shift significantly impacted the expansion of the West Antarctic Ice Sheet, sea ice/polynya formation, and, notably, the genesis of Antarctic Bottom Water (AABW), a crucial component of the global thermohaline circulation. In Chapter 1, we propose that turbidite currents, arising from the formation of dense shelf water (DSW) in the Ross Sea (a precursor to AABW), leave a distinct record in the levees of Hillary Canyon. This canyon acts as a conduit, channeling DSW into the deep ocean and contributing to AABW production. By analyzing turbidite beds based on their frequency, thickness, and grain size, we gain insights into the historical occurrence and magnitude of these currents. Furthermore, we explore the influence of factors such as shelf availability and sea ice/polynya formation within the broader climate context of AABW formation. Chapter 2 shifts its focus to the sedimentological variability from shelf-to-slope along Hillary Canyon. This chapter examines the turbidite record associated with AABW formation within the shared timeframe (2.1 to 0.7 million years ago) between IODP Sites U1524 and U1525, and the impact of along slope currents and other processes in the sedimentary deposition and transport. The second study interval (Chapter 3), focuses on the regional sedimentological response proximal to a hydrothermal vent complex associated with the Paleocene-Eocene Thermal Maximum (PETM; ca. 56 Ma), a global warming event during which thousands of Gt C was released into the ocean-atmosphere on Kyr timescales. IODP Site U1568, strategically located near the hydrothermal vent complex and part of a broader drilling transect in the Modgunn Arch, North Atlantic, is the main study subject. This site's proximity to the vent complex offers a distinctive environment for refining our understanding of stratigraphy and sedimentology within the PETM. We achieve this through a comprehensive analysis of grain size and composition, coupled with a comparison to XRF data. Our findings show that the timing between the onset of the PETM and the response of the sedimentary system to the warming, reflected in the grain size coarsening after the start of the PETM, is not synchronous. Notably, the transition from a marine to a more terrestrial composition predates this shift in grain size, aligning with the PETM onset instead. / Doctor of Philosophy / Deep-marine core records are invaluable sources of sedimentological information that provide insights into the ocean's response to past climates. These cores, extracted from the deep-ocean floor, contain layers of sediment that accumulate over time because of the different processes that occur in the ocean. Analyzing these sediments, by looking at their physical characteristics like how frequently are they deposited, the thickness of the layers, their grain size, and their composition helps to reconstruct past environmental conditions and understand how the oceans have responded to climatic changes. This dissertation focuses on studying the record of two main processes. The first one is the sedimentary record left behind by the formation of Antarctic Bottom Water (AABW), one of the coldest (-1°C), deepest (> 2000 meters below sea level), and densest water masses in the ocean. AABW is a key component of the global ocean circulation system, often referred to as the "global conveyor belt" or the thermohaline circulation. This circulation pattern plays a crucial role in redistributing heat, salt, and nutrients around the world's oceans. AABW is formed near Antarctica through a process that begins with the cooling and sinking of surface waters near the continent. As these waters sink, they become denser and eventually form AABW, filling the deep ocean basins around Antarctica. The dense water flows from the surface to the bottom of the ocean forming turbidity currents. These turbidity currents, dense plumes of water and sediments, flow down submarine conduits, such as Hillary Canyon in the Ross Sea, Antarctica, leaving a sedimentary record in the levees or flanks, called turbidites. The turbidite sequences in sediment cores can reveal information about the frequency and magnitude of these currents, providing insights into the sediment transport processes in deep-marine settings, and for this work, the history of the AABW formation over the last 3.3 Ma. This study will help to understand what are the main controls for AABW formation across different climates in the past, and how we project this into the future climate scenarios. In the second part of the study (Chapter 3), we look at the sedimentary record of a warming event that happened around 56 million years ago. This event, known as the Paleocene-Eocene Thermal Maximum (PETM), involved a significant amount of carbon being released into the air and oceans over thousands of years (150,000 to 200,000). Our focus is IODP Site U1568, located near a submarine hydrothermal vent, and part of a larger drilling transect in the North Atlantic's Modgunn Arch. The vent's unique location provides a crucial perspective for understanding how the system responded to the warming during the Paleocene-Eocene Thermal Maximum (PETM). This warming event was triggered by the release of carbon into the atmosphere, with the vent serving as one of the conduits for this release. To understand this, we studied the grain size and content of the sediment, and compared that with XRF data. Changes in grain size serve as indicators of shifts in the energy of the environment – coarser grains signify a more energetic system. Warmer weather, for instance, can increase precipitation, leading to more erosion and sediment influx into the basin. This influx also brings in more materials from the land, as evidenced by the presence of microfossils and plant fragments. Our discoveries indicate that the sedimentary system responded gradually to the PETM, as reflected in the coarsening of grain size after the PETM's onset. Notably, the transition from a marine to a more terrestrial composition occurred before the change in grain size, aligning more closely with the initiation of the PETM itself.

The larger pelagic crustacean fauna of the Gully submarine canyon is described for the first time, based on three annual summer surveys. The larger Crustacea are a significant part of the Gully fauna, and are dominated by cold temperate species, in particular the northern krill Meganyctiphanes norvegica and the decapod Sergestes arcticus. In all, at least 69 species were collected from the surface to bathypelagic depths, with seventeen being new Canadian records. With the exception of M. norvegica, inter-annual variation in the dominant species was minor. The species assemblage varied primarily with depth surveyed and diel cycle, and not year. Comparing the larger pelagic crustaceans in the Gully and over the adjacent continental slope showed that overall species number, biomass, and abundance were all greater in the canyon, the biomass of S. arcticus particularly showing a positive “Gully effect”.

Submarine canyons are major geomorphic features, transporting large quantities of sediments from land to the deep sea. These sediments contain nutrients, enabling life in the deep sea and potentially forming hydrocarbon reservoirs. The transport of sediments towards the deep sea is also important as it links into fundamental concepts of the Earth’s system, such as the global carbon cycle and land surface denudation. Concepts based on the assumption of direct transport of sediments from land to the deep sea. However, how this transport occurs, on what timescales, and if there is potential storage of sediments along the way, is actually poorly known. The current theory is that gravity flow events, such as turbidity events, are the main mechanism behind canyon formation and maintenance. Luminescence dating, an absolute dating method, has been used in an earlier study to look at sediment transport via turbidity currents down the Monterey Canyon, off the coast of California, USA (Stevens et al., 2014). An active upper canyon was found at 1093 metres depth, with frequent events. At 3555 and 3612 metres depth the turbidity events dated were older and indications of major reworking of sediments were found. To pinpoint this change in environments, the present study used luminescence dating in order to get an age estimate of sediments at 2920 meter depth, creating a sequence of ages in the canyon. These cores have captured sediments that have been transported via sand waves, not turbidites. Sand waves are related to the frequent passing of turbidity events, but exact understanding of the mechanisms at hand is poorly understood. Single grain analysis on quartz is used to obtain the individual properties and ages of grains. This gives representative canyon entry ages of the sediments in addition to intrinsic grain properties. The data shows a skewed distribution of grain ages with a narrow, dominant peak between 180 and 240 years within a single core, indicating frequent flushing events and minor reworking of sediments. This is a similar pattern to the core at 1093 meter depth, albeit with increased age, suggesting temporary storage of sediment to at least a depth of 2920 metres. It is proposed that there is a gradual increase in ages down canyon towards 2900 meters depth with a more abrupt transition in environments with increased storage of sediments between 2900 and 3500 meter depth. Sand waves, and the exact relation to turbidites, remain a poorly understood transport mechanisms, but are potentially capable to transport vast amounts of sediments towards the deep sea. / Marina raviner transporterar stora mängder sand från land till havets botten. Men hur sker detta? I nuläget förklaras sandtransport med gravitationsflöde, att gravitationen drar ner sandkornen mot bottnen. Men sker detta vid ett enda stort skede eller i små gradvisa steg? Och kan det vara så att sand, på sin väg till botten, lagras i ravinerna? Det är dessa frågor som jag försöker att kasta ljus på i och med detta projekt.Målet var att komplettera vår kunskap om hur sand förflyttar sig från land till havsbotten genom att studera ifall det har skett en gradvis eller en abrupt transport av sand i ravinen Monterey Canyon vid Kaliforniens kust. Detta har jag gjort genom att datera åldern av sand vid ett djup av 2 920 meter, som i det här fallet deponerats av sandvågor, och sedan jämfört denna ålder med åldrarna på sanden från ett mindre (1 100 m) och större (3 500 m och djupare) djup, vilka analyserades i en tidigare studie (Stevens et al., 2014). Transportmekanism i den studien skiljer sig med min då det rör sig om gravitationsflöden.Med endast några få sandkorn av annan ålder så var den dominerande åldern på kornen i mitt prov mellan 180 till 240 år gamla. Provet vid 1 100 m djup visade sig också ha en liten spridning av ålder vilket tyder på att det skett återkommande utspolning av gammal sand som istället ersatts av ny. Man kan se att det ändå sker en tillfällig lagring av sediment mellan det minsta, studerade djupet och det nyligen tagna provet på 2 900 m, då en svag ökning i ålder kan mätas. Åldern på sandkornen i proven som kom från ett större djup var istället mycket spridd och generellt mycket högre än de från mindre djup. Att det finns en mix av ålder vid ett och samma djup tyder på att sanden vid återkommande tillfällen omfördelats i ravinen.Denna studie antyder att ravinen i fråga är aktiv upp till ett djup av minst 2 920 meter, med bara en svag stegring i ålder med ökande djup. Mellan 2 920 och 3 500 meter ändras miljön vilket gör att sprid-ningen av ålder ökar. Därutöver var det nya provet taget från en plats med ett annorlunda transport-mekanism, sandvågor istället för gravitationsflöde. Sandvågor, och dess relation till gravitationsflöden, är fortsättningsvis en dåligt förstådd transportmekanism som potentiellt är kapabel till att flytta stora mängder sediment till havets botten.

Ce travail présente une analyse de la morphologie et de la dynamique sédimentaire des systèmes turbiditiques actuels du Cap-Ferret et de Capbreton (sud du Golfe de Gascogne). La reconnaissance effectuée sur le système de Capbreton est la première à le considérer dans son ensemble. Ce travail se base sur des données acoustiques de subsurface (sondeur multifaisceaux, sondeur de sédiments Chirp) et de carottages issues de la campagne océanographique Sargass menée par l’Université de Bordeaux. L’analyse morpho-bathymétrique révèle l’organisation amont-aval des géométries sédimentaires dans ces systèmes et, couplée aux données sédimentaires, de préciser les processus de dépôts liés aux écoulements gravitaires. Le fonctionnement holocène du canyon de Capbreton montre des processus gravitaires haute fréquence, révélant son rôle de dépôt-centre pour le sud du golfe de Gascogne. Dans le système du Cap-Ferret, la zone de transition chenal-lobe a été investiguée à fine échelle, documentant ainsi des structures sédimentaires rarement identifiées avec ce niveau de détails dans les systèmes turbiditiques modernes. La dynamique sédimentaire de chacun de ces systèmes est soumise à des forçages auto-cycliques et glacio-eustatiques qui affectent chacun des systèmes de façons différentes. Ces informations ont permis de proposer un modèle régional de fonctionnement sédimentaire au cours des derniers 50 000 ans. / This work presents an analysis of the morphology and sedimentary dynamic of the Cap-Ferret and Capbreton turbidite systems (south Bay of Biscay), containing the first recognition of the whole Capbreton turbidite system. The dataset comprises subsurface geophysical data (multibeam bathymetric and imagery, Chirp sub-bottom profiler) and piston cores, acquired during the oceanographic cruise Sargass conducted by the Bordeaux University. Studied by morpho-bathymetric analyses, the upstream-downstream evolution of the sedimentary bodies joined to the sedimentological data help to understand the active gravity processes of the systems. In the Capbreton system, a special focus is made on its Holocene gravity deposits occurring at high frequencies. In the Cap-Ferret system, the channel-lobe transition zone has been investigated at high resolution and revealed sedimentary structures poorly documented at this scale of details in recent turbidite systems. The glacio-eustatic and autocyclic forcing are expressed in different ways in each turbidite sytem. A regional sedimentary dynamic model is proposed for the last 50,000 years.

L‘estudi dels fluxos de partícules té per objectiu quantificar el carboni que s‘exporta cap a l‘oceà profund, el qual controla el segrest de CO2 atmosfèric a llarg termini. Els marges continentals juguen un paper important en aquest cicle oceànic, ja que són una bomba de carboni i nutrients entre l‘ecosistema terrestre i l'interior de l'oceà. En aquest treball s‘ha investigat la transferència de material al llarg del marge continental del golf de Lleó. Aquest mar-ge, situat al nord-oest de la Mediterrània occidental, està format per una ampla plataforma que s‘estén fins a un talús solcat per un gran nombre de canyons submarins. La major part dels sediments que entren al golf de Lleó provinents dels rius o resuspesos de la plataforma, circulen cap al sud-oest empesos per la circulació ciclònica de la massa d‘aigua i són deflectits majoritàriament a través dels canyons submarins més occidentals (canyons de Cap de Creus i Lacaze-Duthiers) cap a l‘interior de la conca. Aquest procés té lloc sobretot durant les tempestes marines d‘hivern i durant els esdeveniments de cascades submarines. L‘objectiu d‘aquest treball és estudiar la variabilitat temporal i espacial dels fluxos de partícules així com l‘origen i el grau de degradació de la matèria orgànica dins els canyons de Lacaze-Duthiers i Cap de Creus i al talús de la zona més meridional del golf de Lleó. La mesura directa dels fluxos ha estat possible gràcies al fondeig de línies instrumentades dotades amb trampes de sediments i correntímetres al llarg de tres transsectes. Les dades obtingudes indiquen que hi ha una ràpida resposta del sistema als forçaments físics. Així, es detecta una forta relació entre els condicionants atmosfèrics (que desencadenen la cascada d‘aigua densa, les onades i les aportacions fluvials i atmosfèriques), la producció primària, i la quantitat i qualitat del material que sedimenta al llarg del marge continental. La cascada d‘aigua densa de plataforma continental (DSWC) enregistrada durant els mesos de gener, febrer i març de 2006, esdevé el principal factor que controla la sedimentació de partícules a la zona estudiada. Les aigües de la cascada que s‘enfonsen canyó avall, escapen de la constricció que suposa el canyó a la zona baixa, continuen el seu camí paral•leles a les isòbates, i afecten el talús superior. Aquest fet denota la capacitat de la cascada per conduir el material erosionat de la plataforma continental cap als canyons i dispersar-lo cap al talús sud. Per tant, la DSWC pot esdevenir un factor important en la sedimentació en els canyons, el talús i el fons de la conca de la Mediterrània nord-occidental. Independentment dels esdeveniments de DSWC, les parts altes dels canyons estan afectades per un continu intercanvi de material amb la plataforma. Per contra, la zona d‘oceà obert (les zones baixes dels canyons i el talús) rep l‘arribada de material de la plataforma només com a conseqüència directa de la DSWC, mentre que durant la resta de l‘any hi imperen condicions de calma amb el predomini de fluxos pelàgics. La DSWC va ser el principal factor que controlà l‘arriba de matèria orgànica tant marina com terrestre al sistema, amb la transferència de grans quantitats de matèria orgànica d‘orígen terrestre durant el gener de 2006 (provinent de dipòsits de la plataforma), i matèria orgànica d‘orígen marí durant març i abril de 2006 (provinent del bloom fitoplanctònic). Per tant, la dispersió del material orgànic marí i terrestre va ser controlat per les condicions energètiques que afavoriren la resuspensió i el transport mar endins del material de la plataforma. La matèria orgànica es degradà no només durant el seu transport al llarg dels canyons, sinó també a través de la columna d'aigua, abans d'arribar a la zona de convergència dels canyons i al talús obert. Tot i que les aportacions laterals de matèria orgànica de la plataforma adjacent predominaren durant els esdeveniments de DSWC, les aportacions provinents d‘esdeveniments esporàdics de producció primària i la constant advecció de material marí varen ser evidents durant períodes de condicions energètiques i fluxos baixos. / Particle flux studies aim at quantifying the amount of carbon and other components that are exported into deep ocean, which controls the long term atmospheric CO2 sequestration. Continental margins play an important role in this oceanic cycle as they pump carbon and nutrients from aerial ecosystems to the interior of the ocean. This work analyzes the transference of material along the continental margin of the Gulf of Lion. This margin, located in the northwestern Mediterranean, is a broad platform that extends to a slope cut by a large number of submarine canyons. Most of the sediments entering the system by rivers or resuspension in the shelf travel to the southwest due to the cyclonic circulation where are deflected mainly through the Cap de Creus and Lacaze-Duthiers submarine canyons to the deep basin. This process occurs mainly during winter sea storms and dense shelf water cascading events. The pourpose of this study is to analyze the temporal and spatial variability of particle fluxes and the source and degree of degradation of the organic matter within the Lacaze-Duthiers and Cap de Creus submarine canyons and the southern slope, in the Gulf of Lion. Direct flux measurements has been carried out by the deployment of 9 in-strumented lines equipped with sediment traps and currentmeters along three transects along the axis of the Lacaze-Duthiers and Cap de Creus canyons and the southern slope. Data indicate that there is a quick response of the system to physical forcings, with a close relation among atmospheric drivers (that trigger the dense water cascade, waving and river and atmospheric inputs), primary production, and the quantity and quality of settling material across the continental margin. The severe dense shelf water cascading (DSWC) event observed during January-March 2006 was the main factor controlling the sedimentation in the studied area. The dense waters escaped the lower canyon where it widens to flow along the isobaths and impacted the southern open slope. This denotes the capacity of such events to funnel and spread southwardly shelf eroded material through canyons. Therefore DSWC may become an important factor for the sedimentation in the middle and lower slope of the northwestern Mediterranean. Upper and middle canyon was primarily affected by continuous cross-slope exchanges with the shelf. The deeper ones were less affected by horizontal transferences and shelf material arrived only associated to the DSWC event, whereas outside the DSWC period pelagic fluxes become a significant part of the total mass flux. The severe DSWC event controlled also the arrival of organic matter to the sea floor, with the transfer of large quantities of land derived organic matter in January 2006 (from shelf deposits), and marine derived organic matter in March-April 2006 (from the concomitant spring bloom). Therefore, the timing of the dispersion of both terrigenous and marine derived organic material was controlled by the energetic conditions that enhance the resuspension and offshore transport of material in the shelf. In addition, this organic matter was degraded not only during its transport along the canyons but also in the water column before reaching the canyon mouth and open slope, as indicated by trends in amino acid and chloropigment concentrations and compositions. Furthermore, although lateral input of organic matter from the adjacent shelf predominated during DSWC events, sporadic primary production events and constant advection of land derived material were also evident during low energy and low flux periods.

La marge provençale, localisée au Nord-Ouest de la Méditerranée, constitue avec la marge du Golfe du Lion et la marge ligure, la bordure septentrionale du bassin Liguro-Provençal. L'objectif principal de ce travail est la reconstitution de l'histoire géodynamique, structurale et géomorphologique de la marge depuis le Tertiaire. Sa structure est principalement le résultat des phases tectoniques anté-miocènes. Sur la marge provençale la transition entre le plateau continental et le bassin est étroite et caractérisée par des pentes abruptes affectées par des phénomènes d'instabilité gravitaire dans l'axe du canyon sous-marin de Cassidaigne. A terre, la marge provençale est caractérisée par une compression pyrénéenne, des fossés oligocènes, et une sédimentation mésozoïque à cénozoïque essentiellement carbonatée propice à l'infiltration des eaux en profondeur. L'origine des cours d'eau de la région est essentiellement karstique, et les sources côtières de Port-Miou et Bestouan constituent des réseaux karstiques noyés développés sur plusieurs kilomètres dans le calcaire urgonien, au droit du canyon de Cassidaigne. Les travaux antérieurs suggèrent que l'absence de réseau fluviatile de surface en amont et la forme de reculée karstique de la tête du canyon de Cassidaigne sont le résultat d'une connexion karstique entre les sources côtières et le canyon, que la marge provençale n'ait pas été affectée par l'érosion messinienne et la transgression pliocène, que certains dépôts transgressifs marins miocènes sont situés à des altitudes anormalement élevées par rapport à leurs niveaux de dépôt théorique. / The Provence Margin is situated in the north-western Mediterranean and constitutes the northern edge of the Liguro-Provençal Basin with the margins of the Gulf of Lion and Ligurian sea. The main objectif of this thesis is the reconstruction of the geodynamic, structural and geomorphologic history of the margin since the Tertiary. This margin is mainly structured by ante-miocene tectonic events. On the Provence Margin, transition between the continental plate and the basin is narrow and characterized by abrupt slopes and associated gravitary instability within the axis of the Cassidaigne canyon. The Provence Margin is characterized by Pyrenean compression and Oligocene extension. The Mesozoïc-Cenozoïc sedimentary pile is dominated by carbonate rocks favorable to water circulation. The origin of the river system in the region is essentially karstic, and the coastal springs of Port-Miou and Bestouan correspond to drowned karstic network that develop along tens of kilometers within the Urgonian limestone, updip of the Cassidaigne Canyon. Previous work suggest (1) that the lack of updip river system and the karst pocket valley shape of the canyon head are the result of an active karstic connexion between the coastal springs and the canyon, (2) that the Provence Margin is not affected by the Messinian erosion and Pliocene transgression, and (3) that Miocene marine transgressions are preserved at higher altitudes than their theoretical level. These facts witness a recent tectonic deformation that is not well understood. This work is based on the integration of geology, geomorphology and hydrogeology with the aim to understand evolution and functioning of coastal karsts

Cette étude présente les architectures et la dynamique sédimentaire de la pente carbonatée au nord de Little Bahama Bank (Bahamas) à partir des données de sondeur multifaisceaux, de sondeur de sédiments (Chirp) et de sismique multitraces Haute Résolution (HR) issues de la mission Carambar 1(2010). Une analyse morpho-sédimentaire de surface permet de définir les grands domaines physiographiques et les éléments architecturaux de la pente et précise la répartition spatiale des sédiments dans le contexte actuel de haut niveau marin relatif. Elle révèle une pente dominée par de la boue de périplate-forme avec différents niveaux d’induration et entaillée par des glissements et des canyons sous marins.La variabilité spatiale du transfert de boue depuis la plate-forme vers la pente, couplée à l’évolution latérale de l’intensité du courant des Antilles est à l’origine de grandes différences morphologiques d’est en ouest. Dans la partie occidentale, la pente est environ deux fois plus étendue que dans la partie orientale,elle s’apparente à un système progradant. La pente orientale, quant à elle, est marquée par des processus de bypass. En effet, cette partie est caractérisée par de nombreux canyons sous-marins se poursuivant par des sillons distributaires alimentant des zones de dépôts distales confinées. Une étude intégrée permet la caractérisation à haute résolution des glissements et des canyons et la proposition d’un modèle déformation. Ces éléments architecturaux sont initiés par des déstabilisations intra-pente et leur évolution est contrôlée par des épisodes d’érosion régressive, la sédimentation pélagique et les écoulements gravitaires boueux. Enfin, une analyse sismo-stratigraphique permet de reconstituer l’évolution tectono-sédimentaire de la pente de l’Albien à l’Actuel en lien avec le contexte géodynamique des Caraïbes, l’eustatisme et la production carbonatée sur la plate-forme. / This study focuses on the architectures and the sedimentary dynamic of a carbonate slope located on the northern part of Little Bahama Bank (Bahamas) using a dataset composed of multibeam echo sounder,subbottom profiler (Chirp) and High-Resolution (HR) multichannel seismic collected during the Carambar 1cruise (2010). A morpho-sedimentary surface analysis defines the physiographic domains and the architectural elements of the slope and investigates the spatial distribution of sediments in the context of the current sea-level highstand. It reveals a slope dominated by periplatform ooze with several levels of induration and incised by numerous slides and submarine canyons. The spatial variability of off-bank transport, combined with the lateral variability of the Antilles Current intensity, are at the origin of a morphological evolution from west to east in the study area. In the western part, the slope is around twice as large as the eastern part and can be considered as a prograding system. The eastern slope is marked by bypass processes. Indeed, numerous submarine canyons are visible on the seafloor and are connected to several shallow distributary furrows feeding confined depositional areas. An integrated study allows a high resolution characterisation of slides and submarines canyons and enables us to propose a model of formation. These architectural elements are initiated by intra-slope destabilisations and their evolution is controlled by phases of retrogressive erosion,pelagic sedimentation and muddy gravity flows. Finally, a seismo-stratigraphic analysis allow to reconstitutethe tectonic and sedimentary evolution of the slope since the Albian to the present-day by establishing a link with the geodynamic context of Caraïbes, relative sea-level changes and the carbonate production on the platform.