Search

Your search keyword '"Vincent Hanquiez"' showing total 71 results
Start Over Author "Vincent Hanquiez"
71 results on '"Vincent Hanquiez"'

1. Microscopic charcoals in ocean sediments off Africa track past fire intensity from the continent

Author

Aritina Haliuc, Anne-Laure Daniau, Florent Mouillot, Wentao Chen, Bérangère Leys, Valérie David, Vincent Hanquiez, Bernard Dennielou, Enno Schefuß, Germain Bayon, and Xavier Crosta

Subjects
Geology, QE1-996.5, Environmental sciences, GE1-350
Abstract

Abstract Fires in Africa account for more than half of global fire-carbon emissions but the long-term evolution of fire activity and its link to global climate change remains elusive. Paleofire records provide descriptive information about fire changes through time, going beyond the range of satellite observations, although fire regime characteristics are challenging to reconstruct. To address this conceptual gap, we report here the abundance and morphometric data for a large set of microscopic charcoal samples (n = 128) recovered from surface ocean sediments offshore Africa. We show that in subtropical Southern Africa, large and intense fires prevailing in open savanna-grassland ecosystems produce a high abundance of small and elongated microcharcoal particles. In contrast, in the forest ecosystems of equatorial and tropical regions of western and central Africa, low-intensity fires dominate, producing low amounts of squared microcharcoal particles. Microcharcoal concentration and morphotype in marine sediment records off Africa are thus indicative of fire regime characteristics. Applied to down-core marine charcoal records, these findings reveal that at orbital time-scale intense and large, open grassland-savanna fires occurred during wet periods in the sub-tropical areas. A strong contribution of fire carbon emissions during periods of precession and summer insolation maxima in the geological record is thus expected.

Published
2023
Full Text
View/download PDF

2. Monitoring Sea Level and Topography of Coastal Lagoons Using Satellite Radar Altimetry: The Example of the Arcachon Bay in the Bay of Biscay

Author

Edward Salameh, Frédéric Frappart, Vincent Marieu, Alexandra Spodar, Jean-Paul Parisot, Vincent Hanquiez, Imen Turki, and Benoit Laignel

Subjects
radar altimetry, coastal altimetry, sea surface height, topography of the intertidal zone, ERS-2, ENVISAT, SARAL, CryoSat-2, Science
Abstract

Radar altimetry was initially designed to measure the marine geoid. Thanks to the improvement in the orbit determination from the meter to the centimeter level, this technique has been providing accurate measurements of the sea surface topography over the open ocean since the launch of Topex/Poseidon in 1992. In spite of a decrease in the performance over land and coastal areas, it is now commonly used over these surfaces. This study presents a semi-automatic method that allows us to discriminate between acquisitions performed at high tides and low tides. The performances of four radar altimetry missions (ERS-2, ENVISAT, SARAL, and CryoSat-2) were analyzed for the retrieval of sea surface height and, for the very first time, of the intertidal zone topography in a coastal lagoon. The study area is the Arcachon Bay located in the Bay of Biscay. The sea level variability of the Arcachon Bay is characterized by a standard deviation of 1.05 m for the records used in this study (2001–2017). Sea surface heights are very well retrieved for SARAL (R~0.99 and RMSE < 0.23 m) and CryoSat-2 (R > 0.93 and RMSE < 0.42 m) missions but also for ENVISAT (R > 0.82 but with a higher RMSE >0.92 m). For the topography of the intertidal zone, very good estimates were also obtained using SARAL (R~0.71) and CryoSat-2 (R~0.79) with RMSE lower than 0.44 m for both missions.

Published
2018
Full Text
View/download PDF

4. Linking carbonate sediment transfer to seafloor morphology: Insights from Exuma Valley, the Bahamas

Author

Hervé Gillet, Emmanuelle Ducassou, Thibault Cavailhes, Marie-Claire Perello, Audrey Recouvreur, Johan Le Goff, Thierry Mulder, Vincent Hanquiez, Natacha Fabregas, and John J. G. Reijmer

Subjects
010506 paleontology, Turbidity current, Knickpoint, Stratigraphy, Sorting (sediment), Sediment, Geology, 010502 geochemistry & geophysics, 01 natural sciences, Turbidite, Sedimentary depositional environment, chemistry.chemical_compound, Paleontology, chemistry, General Earth and Planetary Sciences, Carbonate, Sediment transport, 0105 earth and related environmental sciences, General Environmental Science
Abstract

The depositional record of carbonate slopes provides a valuable archive of past environmental and climatic changes. Modern carbonate slopes reveal morphological variabilities (for example, gullies and canyons) shaped by episodic slope collapses and turbidity currents. Furthermore, climate-induced fluctuations in sea level regulate sediment availability and delivery to the deep-sea. Morphological and climatic controls on calciclastic sediment transfer are often complex to decipher. The aim of this study is to link seafloor morphology and depositional processes in an active carbonate submarine channel (Exuma Valley, the Bahamas) over the last 40 kyr. The dataset includes multibeam and seismic surveys, and two sediment cores retrieved from the valley axis. A series of abrupt slope-breaks, called knickpoints, occurs along Exuma Valley, and plays a key role in sediment transport and accumulation. Initiation processes proposed for knickpoint formation include bank-collapse, side gully erosion and loss of confinement. Slope collapses detected on the bathymetry prevail in the upstream muddy section of the submarine valley, as attested to by a planktic-rich debrite–turbidite couplet in the first core. In contrast, the second core collected downstream of the knickpoints train, includes 32 bioclastic sandy event-beds (i.e. turbidites). Hydrodynamic sorting generates grain segregation (for example, Halimeda-rich base versus planktic-rich top) and geochemical contrasts (Sr/Ca) in turbidites. Turbidite frequency and grain composition within beds reflect the variation of carbonate sources during glacial–interglacial periods. This research allows to link slope morphology with deposits of a modern large-scale carbonate factory, and to deduce sea-level changes over that last 40 kyr in the Bahamas. These results can provide new perspectives on the understanding of ‘source to sink’ mechanisms in carbonate systems.

Published
2020

5. The abyssal giant sinkholes of the Blake Bahama Escarpment: evidence of focused deep-ocean carbonate dissolution

Author

Thibault Cavailhes, Hervé Gillet, Léa Guiastrennec-Faugas, Thierry Mulder, and Vincent Hanquiez

Subjects
Tectonics, Carbonates, Sinkholes, Escarpments, Earth-Surface Processes
Abstract

This study reports the discovery of abyssal giant depressions located at the toe of the Bahamian carbonate platform, along the Blake Bahama structurally-controlled Escarpment (BBE) that exhibits up to 4 km of submarine elevation above the San Salvador Abyssal Plain (SSAP). Analysis of seismic reflection and bathymetric data collected during the CARAMBAR 2 cruise revealed the presence of 29 submarine depressions; their water depths range from 4584 m to 4967 m whereas their negative reliefs are elliptical in shape, range in diameter from 255 m to 1819 m, and in depth from 30 m to 185 m. The depression alignment trends are parallel to the BBE as well as to structural lineaments of the area, exclusively between 2200 and 5000 m from its toe, and overlies a buried carbonate bench in which a high-amplitude seismic anomaly has been detected. The depression density interestingly increases where the recognized structural lineaments intersect the BBE. Based on their physical attributes (i.e. location, jagged morphologies, water depths), we interpret these depressions as collapse sinkholes rather than pockmarks or plunge pools. The aforementioned observations suggest an atypical relationship between the spatial occurrence of the giant abyssal sinkholes, the carbonate platform tectonic structures, the buried carbonate bench that underlies the hemipelagites in the SSAP and the geomorphology of the area. According to the wider literature that reports fluid seepages along submarine carbonate escarpments, we propose that the ground water entrance during low sea-level stands, the dissolution of evaporites by meteoric water, the platform-scale thermal convection and the seawater entrance at the platform edge most probably collectively act in concert to favor the circulation of brines and therefore the corrosion within the Bahamian carbonate platform. These mechanisms are particularly efficient along the structural heterogeneities (e.g. the Sunniland Fracture Zone, SFZ) which act as fluid conduits localizing the dissolution and control the physiography of the area by maintaining the location of the sedimentary pathways. The dense fluids would migrate along the faults towards the BBE free edge and are subsequently trapped into the buried carbonate bench that laterally disappears below the low-permeability deep-sea hemipelagites of the SSAP. In consequence, the trapped corrosive fluids dissolve the carbonates preferentially along the tectonic structures such as the SFZ. They are this way at the origin of the BBE curvature and generate collapse-structures in the overlying fine-grained deposits finally resulting in the formation of giant abyssal sinkholes. This structurally-directed process of dissolution seems efficient to provide a brines density head to move out down to >4.5 km of water depth and is believed to have played a major role in the BBE 5–6 km erosional retreat.

Published
2022

6. Source-to-sink pathways of clay minerals in the cadiz contourite system over the last 25 kyrs: The segregational role of mediterranean outflow water

Author

Paul Moal-Darrigade, Marie-Claire Perello, Jacques Giraudeau, Viviane Bout-Roumazeilles, Vincent Hanquiez, Thierry Mulder, Emmanuelle Ducassou, Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 (LOG), Institut national des sciences de l'Univers (INSU - CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Nord]), Centre National de la Recherche Scientifique (CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Institut national des sciences de l'Univers (INSU - CNRS), and Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE)

Subjects
010504 meteorology & atmospheric sciences, [SDV]Life Sciences [q-bio], Geochemistry, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Deposition (geology), Sedimentary depositional environment, Settling, Geochemistry and Petrology, 14. Life underwater, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, [PHYS]Physics [physics], [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Sediment, Geology, Contourite, Last Glacial Maximum, Sedimentation, 13. Climate action, [SDU]Sciences of the Universe [physics], [SDE]Environmental Sciences, Sedimentary rock
Abstract

Despite major advances in our understanding of the interactions between bottom currents and sedimentary deposits over the last forty years, few studies have focused on the nature of fine particles in contourite depositional systems (CDS). XRD analyses of marine sediments can be used to improve our understanding of fine-grained sediment sources and settling processes. This work presents a detailed sedimentological study of sediment cores collected over the middle slope of the Gulf of Cadiz as part of Integrated Ocean Drilling Program Expedition 339 and the 2001 CADISAR cruise. We performed high-resolution clay mineral analyses to reconstruct the pathways of fine-grained particles from their sources to their deposition along the contourite depositional system of the Gulf of Cadiz (source-to-sink approach). The clay mineral associations reflect the major contribution of the Guadalquivir River and North African rivers/dusts to fine particles settling over the middle slope. Our results suggest that size segregation deposition processes along the path of the Mediterranean Outflow Water (MOW) are responsible for the distinct clay mineral associations between sites located under the upper MOW and the lower MOW. We observed changes of sedimentation rates over the contourite depositional system throughout the last 25 kyrs. We propose that these changes are due to temporal variations in the vertical distribution of the upper and the lower MOW whose concentrations in suspended particulate matter are drastically different. Sea-level and large scale atmospheric changes (e.g., ITCZ migration) over this period induced major variations in the distance of river mouths to the Gulf of Cadiz CDS, and in the amount of Northwest African dust delivered to this depositional system, respectively. Climate changes therefore modified fine particle sources and pathways, which considerably influenced clay minerals settling in the middle slope of the Gulf of Cadiz since the Last Glacial Maximum.

Published
2022

7. Contour current imprints and contourite drifts in the Bahamian archipelago

Author

Hervé Gillet, Ludivine Chabaud, Jean Borgomano, Kelly Fauquembergue, E. Tournadour, Paul Moal, Emmanuelle Ducassou, Anais Schmitt, John J. G. Reijmer, Vincent Hanquiez, Mélanie Principaud, Audrey Recouvreur, Thierry Mulder, Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE)-Centre National de la Recherche Scientifique (CNRS), King Fahd University of Petroleum and Minerals (KFUPM), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Collège de France (CdF)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Institut National de la Recherche Agronomique (INRA), Earth Sciences, Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), and Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
drifts, 010506 paleontology, contour currents, Bahamas, Stratigraphy, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Escarpment, 010502 geochemistry & geophysics, 01 natural sciences, Deposition (geology), Paleontology, 14. Life underwater, SDG 14 - Life Below Water, Seabed, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, geography, geography.geographical_feature_category, Abyssal plain, Sediment, contourites, Geology, Contourite, Erosion, Siliciclastic
Abstract

New data collected along the slopes of Little and Great Bahama Bank and the abyssal plain of the Bahama Escarpment provides new insights about contour current-related erosive structures and associated deposits. The Bahamian slope shows abundant evidence of bottom current activity such as furrows, comet-like structures, sediment waves and drifts. At a seismic scale, large erosion surfaces and main periods of drift growth resulted from current acceleration related to plate tectonic processes and progressive opening and closure of gateways and long-term palaeoclimate evolution. At present-day, erosion features and contourite drifts are either related to relatively shallow currents (2500 m water depth). It appears that the carbonate nature of the drifts does not impact the drift morphology at the resolution addressed in the present study. Classical drift morphologies defined in siliciclastic environments are found, such as mounded, plastered and separated drifts. In core, contourite sequences show a bi-gradational trend that resembles classical contourite sequences in siliciclastic deposits showing a direct relationship with a change in current velocity at the sea floor. However, in a carbonate system the peak in grain size is associated with increased winnowing rather than increased sediment supply as in siliciclastic environments. In addition, the carbonate contourite sequence is usually thinner than in siliciclastics because of lower sediment supply rates. Little Bahama Bank and Great Bahama Bank contourites contain open-ocean input and slope-derived debris from glacial episodes. Inner platform, platform edge and open ocean pelagic input characterize the classical periplatform ooze during interglacials. In all studied examples, the drift composition depends on the sea floor topography surrounding the drift location and the type of sediment supply. Carbonate particles are derived from either the slope or the platform in slope and toe of slope drifts, very deep contourites have distant siliciclastic sources of sediment supply. The recent discovery of the importance of a large downslope gravitary system along Bahamian slopes suggests frequent interactions between downslope and along-slope (contour currents) processes. The interlayering of mass flow deposits and contourites at a seismic scale or the presence of surface structures associated with both contour currents and mass flow processes shows that both processes act at the same location. Finally, contour currents have an important impact on the repartition of deep-water coral mounds. Currents can actively interact with mounds as a nutrient and oxygen supplier or have a passive interaction, with mounds solely being obstacles orienting erosion and deposition.

Published
2019

8. Into the deep: A coarse-grained carbonate turbidite valley and canyon in ultra-deep carbonate setting

Author

Thierry Mulder, Vincent Hanquiez, J. Le Goff, Audrey Recouvreur, Kelly Fauquembergue, Sara Bashah, John J. G. Reijmer, Jean Borgomano, Stéphane Bujan, Jérémy Ragusa, L. Guiastrennec, Mélanie Principaud, D.G. Blank, Gilles Conesa, Natacha Fabregas, Thibault Cavailhes, Hervé Gillet, Chloé Seibert, J. Busson, Emmanuelle Ducassou, André W. Droxler, UMR 5805 Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE)-Centre National de la Recherche Scientifique (CNRS), King Fahd University of Petroleum and Minerals (KFUPM), Rice University [Houston], Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Rosenstiel School of Marine and Atmospheric Science (RSMAS), University of Miami [Coral Gables], Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Collège de France (CdF)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Institut National de la Recherche Agronomique (INRA), Section of Earth and Environmental Sciences [Geneva], University of Geneva [Switzerland], IFP Energies nouvelles (IFPEN), Environnements et Paléoenvironnements OCéaniques (EPOC), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Earth and Environmental Sciences [Geneva], Université de Genève = University of Geneva (UNIGE), Earth Sciences, Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Université Paris Diderot - Paris 7 (UPD7)-IPG PARIS-Institut national des sciences de l'Univers (INSU - CNRS), and Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA)

Subjects
010504 meteorology & atmospheric sciences, Carbonate platform, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Escarpment, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, chemistry.chemical_compound, Paleontology, Geochemistry and Petrology, SDG 14 - Life Below Water, 14. Life underwater, Slumping, 0105 earth and related environmental sciences, Canyon, geography, geography.geographical_feature_category, Plateau, Abyssal plain, Geology, chemistry, Carbonate, Siliciclastic
Abstract

International audience; New high-resolution multibeam mapping images detail the southern part of Exuma Sound (Southeastern Bahamas), and its unchartered transition area to the deep abyssal plain of the Western North Atlantic, bounded by the Bahama Escarpment extending between San Salvador Island and Samana Cay. The transition area is locally referred to as Exuma Plateau. The newly established map reveals the detailed and complex morphology of a giant valley draining a long-lived carbonate platform from its upper slope down to the abyssal plain. This giant valley extends parallel to the slope of Long Island, Conception Island, and Rum Cay. It starts with a perched system flowing on top of a lower Cretaceous drowned main carbonate platform. The valley shows low sinuosity and is characterized by several bends and flow constrictions related to the presence of the small relict isolated platforms that kept alive longer than the main platform before drowning and merging tributaries. Turbidite levees on either side of the valley witness the pathway of multiple gravity flows, generated by upper slope over steepening around Exuma Sound through carbonate offbank transport, some of them locally >15°, and resulting slumping. In addition, additional periplatform sediments are transported to the main valley through numerous secondary slope gullies and several kilometre-long tributaries, draining the upper slopes of cays and islands surrounding Exuma Plateau. Some of them form knickpoints indicating surincision of the main Exuma Valley which is consistent with an important lateral supply of the main Exuma Valley. Prior to reaching the abyssal plain, the main valley abruptly evolves into a deep canyon, 5 km in width at its origin and as much as 10 km wide when it meets the abyssal plain, through two major knickpoints named “chutes” with outsized height exceeding several hundred of meters in height. Both chutes are associated with plunge pools, as deep as 200-m. In the deepest pools, the flows generate a hydraulic jump and resulting sediment accumulation. When the canyon opens to the San Salvador abyssal plain, the narrow, deep, and strong flows release significant volume of coarse-grained calcareous sediments in numerous turbidite layers interbedded with fine mixed siliciclastic and carbonate sediments transported by the Western Boundary Undercurrent (WBUC) along the Bahama Escarpment. Carbonate gravity flows exiting the canyon decelerate at the abyssal plain level and construct a several-kilometre-wide coarse-grained deep-sea turbidite system with well-developed lobe-shape levees, partially modified by the flow of strong contour-currents along the Bahama Escarpment.

Published
2019

9. Modern relationships between microscopic charcoal in marine sediments and fire regimes on adjacent landmasses to refine the interpretation of marine paleofire records: an Iberian case study

Author

Florent Mouillot, Polychronis C Tzedakis, Filipa Naughton, Maria Fernanda Sánchez-Goñi, Anne-Laure Daniau, Muriel Georget, Pierre Anschutz, Thierry Mulder, David A. Hodell, Fatima F Abrantes, Bernard Dennielou, Marion Genet, Vincent Hanquiez, Jérôme Bonnin, Valérie David, Linda Rossignol, Franck Bassinot, Sabine Schmidt, Frédérique Eynaud, Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), ANR BRAISEFrench INSU (Institut National des Sciences de l'Univers) programme LEFE (Les Enveloppes Fluides et l’Environnement) CAMPFIRE projectESA FIRECCI, ANR-19-CE01-0001,BRAISE,Reconstruction des surfaces brulées à partir des particules de microcharbon préservées dans le sédiment marin(2019), and EPOC - CNRS, UMR 5805

Subjects
Mediterranean climate, Archeology, 010504 meteorology & atmospheric sciences, Microcharcoal, Climate, Marine surface sediments, 010502 geochemistry & geophysics, 01 natural sciences, Iberian peninsula, Western europe, River mouth, Glacial period, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Ecology, Evolution, Behavior and Systematics, Holocene, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, geography, geography.geographical_feature_category, Vegetation, Fire regime, Sediment, Geology, 15. Life on land, 13. Climate action, [SDU]Sciences of the Universe [physics], Interglacial, Calibration, Physical geography
Abstract

Marine microcharcoal records provide invaluable information to understand changes in biomass burning and its drivers over multiple glacial and interglacial cycles and to evaluate fire models under warmer climates than today. However, quantitative reconstructions of burnt area, fire intensity and frequency from these records need calibration studies of the current fire-microcharcoal relationship. Here, we present the analysis of microcharcoal concentration and morphology in 102 core-top sediment samples collected in the Iberian margin and the Gulf of Cadiz. We show that microcharcoal concentrations are influenced by the water depth or the distance from the river mouth. At regional scale, the mean microcharcoal concentrations and microcharcoal elongation (length to width ratio) show a marked latitudinal variation in their distribution, primarily controlled by the type of burnt vegetation in the adjacent continent. High microcharcoal concentrations in marine sediments represent rare, large and intense fires in open Mediterranean woodlands. Based on these results, the increasing trend of microcharcoal concentrations recorded since 8 ka in the well-known marine sedimentary core MD95-2042 off the Iberian margin indicates the occurrence of large and infrequent fires of high intensity due to the progressive degradation of the Mediterranean forest and the expansion of shrublands. info:eu-repo/semantics/publishedVersion

Published
2021

10. Synthèse cartographique de la pente des Bahamas

Author

Thierry Mulder, Kelly Fauquembergue, Vincent Hanquiez, Stanislas Wilk, Emmanuelle Ducassou, Emmanuelle Poli, and Sciencesconf.org, CCSD

Subjects
[SDU] Sciences of the Universe [physics], élément architectural, Bahamas, Corps sédimentaires, carbonates, pente
Published
2021

11. Geomorphology of a modern carbonate slope system and associated sedimentary processes: Example of the giant Great Abaco Canyon, Bahamas

Author

Thierry Mulder, E. Tournadour, Vincent Hanquiez, Jean Borgomano, Stanislas Wilk, Emmanuelle Poli, Hervé Gillet, Natacha Fabregas, Kelly Fauquembergue, Jean‐Baptiste Kucharski, Audrey Recouvreur, Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010506 paleontology, Backscatter, Bahamas, Stratigraphy, Geochemistry, 010502 geochemistry & geophysics, 01 natural sciences, chemistry.chemical_compound, giant canyon, 14. Life underwater, ComputingMilieux_MISCELLANEOUS, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, Canyon, sedimentary processes, geography, geography.geographical_feature_category, Geology, echofacies, chemistry, carbonate slope, [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, sea floor morphology, Carbonate, Sedimentary rock
Abstract

The large acoustic data set acquired during the Carambar cruises is composed of high resolution bathymetry, backscatter data and very‐high resolution seismic lines which allow for an overview of the morphology and sediment transfer processes from the shallow upper slope to the abyssal plain of a modern carbonate system: the north‐eastern slope of the Little Bahama Bank. Surficial distribution of the acoustic facies and echofacies reflects a wide variety of sedimentary processes along and across the slope. The western sector of the Little Bahama Bank is dominated by depositional processes whereas its eastern sector, which is incised in the lower slope by giant canyons, is affected by erosion and bypass processes. Datasets suggest that currents play an important role both along‐slope sedimentary processes and in the abyssal plain. The Antilles Current appears to affect a large part of the middle and lower slopes. The absence of sizable present‐day channel/levée complexes or lobes at the mouth of the canyon – revealed by the bathymetric map – indicates that the southward flowing Deep Western Boundary Current influences modern abyssal sediment deposition. Based on depositional processes and indicators of canyon maturity observed in facies distribution, the current study proposes that differential subsidence affects the eastern versus western part of the bank. The morphology of the Great Abaco Canyon and Little Abaco Canyon, which extends parallel to the platform, and the Little Bahama Bank slope appears to be related to the Great Abaco Fracture Zone.

Published
2020

12. Upstream migrating knickpoints and related sedimentary processes in a submarine canyon from a rare 20-year morphobathymetric time-lapse (Capbreton submarine canyon, Bay of Biscay, France)

Author

Laure Simplet, Antoine Rousset, Hervé Gillet, Sabine Schmidt, Bernard Dennielou, Léa Guiastrennec-Faugas, Ricardo Silva Jacinto, Vincent Hanquiez, Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Unité de recherche Géosciences Marines (Ifremer) (GM), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), UMR 5805 Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), and Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne)

Subjects
Canyon, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Continental shelf, Morphobathymetry, Geology, Submarine canyon, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Head (geology), Thalweg, Longshore drift, Paleontology, Geochemistry and Petrology, Bathymetric time-lapse, Bathymetry, Sedimentary rock, Knickpoints, [SDU.STU.AG]Sciences of the Universe [physics]/Earth Sciences/Applied geology, 0105 earth and related environmental sciences, cap-breton
Abstract

International audience; The Capbreton submarine canyon is a striking feature of the south-east of the Bay of Biscay. This canyon forms a deep incision through the continental shelf and slope, and displays remarkable structures linked to its present-day hydrosedimentary activity. Its head has been disconnected from the Adour River since 1310 CE, but remains close enough to the coast to be supplied with sediment by longshore drift. Gravity processes in the canyon body are abundantly described and documented, but activity in the head and the fan of the canyon is poorly constrained. Furthermore, many questions remain regarding the details of processes affecting the head, the body and the fan of the Capbreton canyon. In this work, we address the paucity of documentation concerning (1) the temporal evolution of sediment transfer between the head and the deep reaches of the canyon, and (2) the interaction between gravity processes and the morphology of the canyon floor, including both shaping and feedback mechanisms.This study is based on the analysis and comparison of eight multibeam bathymetric surveys acquired in the upper part of the Capbreton canyon between 1998 and 2018, in depths ranging 10–320 m below sea level. This rare time series exposes the morphological evolution of this outstanding dynamic area over the last 20 years. Our work shows that much of the changes are located in the canyon floor and head. Following a period characterized by a unique flat floor thalweg, the canyon was affected by an incision with low lateral terraces which resulted in a narrow axial thalweg. The deepening of the narrow thalweg was induced by retrogressive erosion according to the presence of upstream-migrating knickpoints, while low elevation residual terraces formed as the canyon reached a local equilibrium profile.The flat thalweg observed in 1998 is likely a result of a partial filling of the canyon thalweg by a substantial emptying of the canyon head and significant mass transfer to the proximal part of the canyon. A flat floor thalweg was not observed again in the remaining of our time series (since 2010), suggesting a possible quieter working mode of the canyon. We also propose the first accurate volume quantification of sediment displacement on the canyon floor. Our findings underline the alternation of filling and erosive periods in the canyon axis and an unexpected continuous sediment deposition in the canyon head during the last 20 years.

Published
2020

13. The abyssal giant pockmarks of the Black Bahama Escarpment: Relations between structures, fluids and carbonate physiography

Author

Hervé Gillet, Thibault Cavailhes, Léa Guiastrennec-Faugas, Thierry Mulder, and Vincent Hanquiez

Subjects
geography, geography.geographical_feature_category, Carbonate platform, Pockmark, Abyssal plain, Geochemistry, Escarpment, Abyssal zone, chemistry.chemical_compound, chemistry, Meteoric water, Carbonate, Sedimentary rock, Geology
Abstract

This study reports the discovery of spectacular abyssal giant pockmarks located at the toe of the Bahamian carbonate platform, along the Black Bahama structurally-controlled Escarpment (BBE) that exhibits up to 4 km of submarine elevation above the San Salvador Abyssal Plain (SSAP). Analysis of seismic reflection and bathymetric data collected during the CARAMBAR 2 cruise revealed the presence of 29 pockmarks; their water depths range from −4584 m to −4967 m whereas their bathymetric depressions are elliptical in shape, range in diameter from 255 m to 1819 m, and in depth from 30 m to 185 m. The pockmarks alignment trends parallel to the BBE as well as the structural lineaments of the area, exclusively between 2200 and 5000 m from its toe, and overlies a buried carbonate bench in which a high-amplitude seismic anomaly has been detected. The pockmark density interestingly increases where the recognized structural lineaments intersect the BBE. The aforementioned observations suggest an atypical relationship between the spatial occurrence of the abyssal fluid releases, the carbonate platform tectonic structures, the buried carbonate bench that underlies the hemipelagites in the San Salvador abyssal plain and the physiography of the area. Indeed, the ground water entrance during low-level stands, the dissolution of evaporites by meteoric water, the platform-scale thermal convection and the seawater entrance at the platform edge most probably act in concert to favor the circulation of brines and therefore the corrosion within the Bahamian carbonate platform. These mechanisms are particularly efficient along the structural heterogeneities (i.e. faults and fractures) which act as fluid conduits and control the physiography of the area by maintaining the location of the sedimentary pathways. The dense fluids migrate along the faults towards the BBE free edge and are subsequently trapped into the buried carbonate bench that laterally disappears below the low-permeability deep-sea hemipelagics of the SSAP. In consequence, the trapped corrosive fluids dissolve the carbonates preferentially along the tectonic structures such as the Samana Fracture Zone, at the origin of the BBE curvature and triggers collapse-structures in the overlying fine-grained deposits generating giant pockmarks. This structurally-directed process of dissolution is believed to have played a major role in the BBE 5–6 km erosional retreat and also probably explains the occurrence of plunge pools in the area.

Published
2020

14. Conclusion générale

Author

Sabine Schmidt, Jérôme Baron, Didier Felts, Emmanuel Garnier, Alain Dupuy, Bruno de Grissac, Aldo Sottolichio, Aurélie Chaalali, Alexandra Coynel, David Doxaran, Henri Etcheber, Vincent Hanquiez, Pierre Le Hir, Lauren Ross, and Isabel Jalon-Rojas

Published
2020

17. Estuaire et nappes profondes de Gironde

Author

Sabine Schmidt, Jérôme Baron, Didier Felts, Emmanuel Garnier, Alain Dupuy, Bruno de Grissac, Aldo Sottolichio, Aurélie Chaalali, Alexandra Coynel, David Doxaran, Henri Etcheber, Vincent Hanquiez, Pierre Le Hir, Lauren Ross, and Isabel Jalon-Rojas

Published
2020

19. Recent morphology and sedimentary processes along the western slope of Great Bahama Bank (Bahamas)

Author

Vincent Hanquiez, Ludivine Chabaud, Jean Borgomano, Thierry Mulder, Mélanie Principaud, Emmanuelle Ducassou, and Gregor P. Eberli

Subjects
Paleontology, 010504 meteorology & atmospheric sciences, Seismic facies, Stratigraphy, Geology, Morphology (biology), Sedimentary rock, 010502 geochemistry & geophysics, 01 natural sciences, 0105 earth and related environmental sciences
Published
2018

20. Biostratigraphy of the last 50 kyr in the contourite depositional system of the Gulf of Cádiz

Author

Josette Duprat, Eliane Gonthier, Rim Hassan, Vincent Hanquiez, Thierry Mulder, and Emmanuelle Ducassou

Subjects
010504 meteorology & atmospheric sciences, biology, Limacina retroversa, Pleistocene, Geology, Contourite, Biostratigraphy, 010502 geochemistry & geophysics, Oceanography, biology.organism_classification, 01 natural sciences, law.invention, Foraminifera, Sedimentary depositional environment, Paleontology, Geochemistry and Petrology, law, Radiocarbon dating, Holocene, 0105 earth and related environmental sciences
Abstract

This paper proposes a biostratigraphic framework for the last 50 kyr in the contourite depositional system (CDS) of the Gulf of Cadiz with a solid and independent age control, and tests the reliability of faunal-based analyses in a bottom current-dominated environment related to high current velocities. The distribution of planktonic foraminifera and pteropods has been studied in twenty-two piston cores of the Holocene and Late Pleistocene age from the Gulf of Cadiz. A detailed correlation between the cores has been made possible by a large radiocarbon and isotopic data set and a high degree of similarity of frequency changes within several species by coiling direction changes of Globorotalia truncatulinoides and Globorotalia hirsuta and by occurrences of the polar species Neogloboquadrina pachyderma and Limacina retroversa. Occurrences of these polar species are clearly related to paleoclimatic oscillations and reflect rapidly changing surface water conditions in the Gulf of Cadiz during the latest Pleistocene that have been observed regardless of sedimentation rates and sedimentary environments (contouritic drifts vs slope without bottom current influence).

Published
2018

21. Carbonate slope morphology revealing sediment transfer from bank-to-slope (Little Bahama Bank, Bahamas)

Author

Emmanuelle Ducassou, J. Busson, E. Tournadour, Jara S.D. Schnyder, M. Joumes, John J. G. Reijmer, Jean Borgomano, Mélanie Principaud, Kelly Fauquembergue, Thierry Mulder, Hervé Gillet, Vincent Hanquiez, Ludivine Chabaud, Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Vrije Universiteit Amsterdam [Amsterdam] (VU), University of Miami [Coral Gables], Total M&S [Paris La Defense], TOTAL FINA ELF, IFP Energies nouvelles (IFPEN), and Geology and Geochemistry

Subjects
Turbidity current, 010504 meteorology & atmospheric sciences, Carbonate platform, Stratigraphy, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Escarpment, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, 14. Life underwater, SDG 14 - Life Below Water, Geomorphology, [SDU.STU.AG]Sciences of the Universe [physics]/Earth Sciences/Applied geology, 0105 earth and related environmental sciences, Canyon, geography, geography.geographical_feature_category, Geology, Last Glacial Maximum, Seafloor spreading, Geophysics, Facies, Economic Geology, Quaternary
Abstract

New high-quality multibeam and high-resolution seismic data reveal new observations on sediment transfer and distribution and margin morphometrics in the uppermost slope of Northeastern Little Bahama Bank between 20 and 300 m water depth. The echofacies/backscatter facies show an alongslope sediment distribution forming successive strips. The upper part of the uppermost slope corresponds to the alternation of several submerged coral terraces and escarpments that could be related to Late Quaternary sea-level variations. The terraces could either be related to periods of stagnating sea-level or slow-down in sea-level change and therefore increased erosion by waves, or periods of accelerated sea-level rise since the Last Glacial Maximum. Terraces could therefore be related to coral construction and drowing. The medium part corresponds to the marginal escarpment, a steep cemented area. The lower part of the uppermost slope shows a discontinuous Holocene sediment wedge with varying thickness between 0 and 35 m. It is separated from the upper part by a zone of well-cemented seafloor associated with the marginal escarpment. Passing cold fronts result in sediment export caused by density cascading. The associated sediment fall-out and convective sedimentation can generate density currents that form this wedge and eventually flow through linear structures on the upper slope. The survey reveals the presence of recently active channels that extend over the entire uppermost slope and interrupt the wedge. The channels connect shallow tidal channels to submarine valleys connected to the proximal part of canyons. They directly feed the canyons with platform-derived sediment forming low-density turbidity currents and could supply the deepest part of the system with coarse-grained sediment directly exported from the carbonate platform.

Published
2017

22. Mercury contamination levels in the bioindicator piscivorous fish Hoplias aïmara in French Guiana rivers: mapping for risk assessment

Author

Gilles Durrieu, Patrice Gonzalez, Nathalie Mesmer-Dudons, Agnès Feurtet-Mazel, Alexia Legeay, Valérie Laperche, Sophie Gentès, Régis Vigouroux, Emilie Pauline Dassié, Vincent Hanquiez, Régine Maury-Brachet, Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), UMR 5805 Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), HYDRECO, Laboratoire Environnement de Petit Saut, Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Laboratoire de Mathématiques de Bretagne Atlantique (LMBA), Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Université de Brest (UBO)-Université de Bretagne Sud (UBS)-Centre National de la Recherche Scientifique (CNRS), and Hydreco

Subjects
Gold mining, Health, Toxicology and Mutagenesis, Fishing, chemistry.chemical_element, 010501 environmental sciences, [CHIM.INOR]Chemical Sciences/Inorganic chemistry, Risk Assessment, 01 natural sciences, [MATH.MATH-ST]Mathematics [math]/Statistics [math.ST], Animals, Humans, Environmental Chemistry, Ecotoxicology, 14. Life underwater, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, [SDV.EE]Life Sciences [q-bio]/Ecology, environment, geography, geography.geographical_feature_category, Environmental Biomarkers, biology, business.industry, Fishes, Estuary, Mercury, General Medicine, Contamination, biology.organism_classification, Pollution, 6. Clean water, French Guiana, Mercury (element), Fishery, Mercury . Piscivorous fish . Freshwater . Gold mining . Hydropower . Swamp, chemistry, [SDE]Environmental Sciences, Environmental science, Gold, Hoplias aimara, business, Bioindicator, Water Pollutants, Chemical, Environmental Monitoring
Abstract

International audience; In French Guiana, native populations present high level of mercury contamination, which has been linked to the consumption ofcontaminated fishes. The goal of this study is to undertake a cartography of mercury contamination levels in fishes from the sixmain Guiana rivers. The selected species for this study is the ubiquitous piscivorous fish Hoplias aimara. A total number of 575fishes from 134 discrete fishing sites are regrouped into 51 river sectors. Results from this study permits to rank the six mainGuiana rivers by their mean level of contamination: Oyapock (0.548 mg kg−1), Comté (0.624 mg kg−1), Maroni (0.671 mg kg−1),Approuague (0.684 mg kg−1), Mana (0.675 mg kg−1), and Sinnamary (1.025 mg kg−1). The contamination is however notspatially homogenous along each river, and a map of the different levels of mercury contamination in fishes is provided. Sectorsof low mean Hg contamination are observed both upstream (0.471 mg kg−1) and downstream (0.424 mg kg−1), corresponding toareas without any influence of gold mining activities and areas under the influence of estuarine dilution, respectively. Anoxia andgold mining activities are found to be the two main factors responsible for the high mercury concentration in fish muscles. Whilemean levels of mercury contaminations are higher in anoxia areas (1.029 mg kg−1), contaminations induced by gold miningactivities (0.717 mg kg−1) present the most harmful consequences to human populations. No significant differences in Hgconcentrations are observed between 2005 and 2014 for neither a pristine nor a gold mining area, while Hg concentrationdifferences are observed between former (0.550 mg kg−1) and current gold mining sites (0.717 mg kg−1).

Published
2019

23. The expansion of Central and Northern European Neolithic populations was associated with a multi-century warm winter and wetter climate

Author

William E. Banks, Chantal Leroyer, Maria Fernanda Sanchez Goñi, Vincent Hanquiez, Jacques Giraudeau, Elena Ortu, École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL), UMR 5805 Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), De la Préhistoire à l'Actuel : Culture, Environnement et Anthropologie (PACEA), Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB), Centre de Recherche en Archéologie, Archéosciences, Histoire (CReAAH), Université de Nantes (UN)-Le Mans Université (UM)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Ministère de la Culture (MC), Ministère de la Culture et de la Communication (MCC), French National research Agency [ANR-09-CEP-004-01/OBRESOC], European Community Marie Curie Actions, 'CASE' ITN [238111], Environnements et Paléoenvironnements OCéaniques (EPOC), Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Université de Bordeaux (UB)-Centre National de la Recherche Scientifique (CNRS), Ministère de la Culture (MC), École Pratique des Hautes Études (EPHE), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Le Mans Université (UM)-Université de Rennes (UR)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Université de Nantes - UFR Histoire, Histoire de l'Art et Archéologie (UFR HHAA), Université de Nantes (UN)-Université de Nantes (UN)-Ministère de la Culture (MC), ANR-09-CEPL-0004,OBRESOC,Un observatoire rétrospectif d'une société archéologique: La trajectoire du néolithique Rubané.(2009), Université de Nantes - UFR Histoire, Histoire de l'Art et Archéologie (UFR HHAA), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Ministère de la Culture (MC)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Le Mans Université (UM), Nantes Université (NU)-Ministère de la Culture (MC)-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes 1 (UR1), and Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université de Rennes 2 (UR2)

Subjects
010506 paleontology, Archeology, [SHS.ARCHEO]Humanities and Social Sciences/Archaeology and Prehistory, 010504 meteorology & atmospheric sciences, fluctuations, tree-line area, Climate change, data set, medicine.disease_cause, 01 natural sciences, pollen data, Spatial reconstruction, Pollen, medicine, Precipitation, ComputingMilieux_MISCELLANEOUS, Holocene, surface sediments, 0105 earth and related environmental sciences, Earth-Surface Processes, Global and Planetary Change, Ecology, reconstructions, Paleontology, Subsistence agriculture, Vegetation, Geography, atlantic oscillation, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, 13. Climate action, Climatology, trondheimsfjord, Period (geology), central norway, holocene climate
Abstract

International audience; It is still debated whether climate changes had an impact on the emergence, spread, and disappearance of early production-based (Neolithic) adaptations. To date, and despite the incorporation of various paleoclimatic proxies, there exists no spatial reconstruction of the regional impact of the North Atlantic cooling events on Central-Western European climate and environments during the early Holocene. In order to address these two issues, we estimated seasonal and annual temperature and precipitation from a marine pollen record from Trondheimsfjord (central Norway) along with 68 pollen records distributed across Central-Western Europe for the time period associated with the Linearbandkeramik (LBK) cultural tradition, 7600-6900 yr cal. BP. Two distinct vegetation-derived rapid

Published
2016

24. Sediment failure types, preconditions and triggering factors in the Gulf of Cadiz

Author

A. Régert, D. Leynaud, Eliane Gonthier, Thierry Mulder, and Vincent Hanquiez

Subjects
geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Sediment, Landslide, Escarpment, 010502 geochemistry & geophysics, Geotechnical Engineering and Engineering Geology, 01 natural sciences, Seafloor spreading, Tectonics, Discontinuity (geotechnical engineering), Bathymetry, Geomorphology, Seismology, Geology, 0105 earth and related environmental sciences, Mud volcano
Abstract

A series of morphological structures, such as scars and escarpments related to seafloor instabilities, were observed in the Gulf of Cadiz using multibeam bathymetry and acoustic imagery. According to the geometry of the slide scars, the slope angle, the surrounding seafloor morphology and the mechanical parameters of the sediment, we suggest the likely mechanisms initiating the failures for the different types of observed structures. Most of the small-scale sediment failures (≤2 km2) seem directly related to dome-like structures (where slopes are steep) or are located in the vicinity of such structures (fluid flows). It appears that progressive deformation or fluid flow related to the growing of dome-like structures may have weakened the sediments sufficiently to bring 7°-steep slopes to metastable conditions (with a factor of safety close to 1.0). The other instability types are likely related to high-magnitude (Ms > 6) earthquakes, which are prone to occur in this area (located in the neighbourhood of the 1755 Lisbon earthquake area). Some particular large-scale structures were observed among these seafloor features, for example on the Guadalquivir Bank. On this bank, a series of successive large scars (at least 4 km long), composed of multiple and very regular arcuate segments (1 km in diameter), were observed at different bathymetric levels (every 40 m). These structures might be related to a deep-rooted detachment zone (e.g. successive listric faults) and triggered by high-magnitude earthquakes or by accumulated displacement along a tectonic discontinuity. This would explain such a large-scale deformation, providing a regular escarpment of 40 m high without any sediment flow downslope, thereby suggesting an ongoing (or unfinished) deformation.

Published
2016

25. Sedimentary processes determining the modern carbonate periplatform drift of Little Bahama Bank

Author

Gilles Conesa, Emmanuelle Ducassou, John J. G. Reijmer, Ludivine Chabaud, E. Tournadour, Thierry Mulder, Jacques Giraudeau, Vincent Hanquiez, Lauren Ross, Jean Borgomano, Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Collège de France (CdF)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Institut National de la Recherche Agronomique (INRA), Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Université d'Alexandrie, College of Petroleum Engineering and Geosciences, King Fahd University of Petroleum and Minerals (KFUPM), Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), TOTAL S.A., TOTAL FINA ELF, Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA), UMR 5805 Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), and Geology and Geochemistry

Subjects
010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Geology, Contourite, Pelagic sediment, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Geochemistry and Petrology, Interglacial, Sedimentary rock, 14. Life underwater, Glacial period, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, SDG 14 - Life Below Water, Geomorphology, Sediment transport, Seabed, Sea level, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences
Abstract

International audience; This paper presents an analysis of the combined influence of along-slope sediment transport and off-bank sediment export from the Little Bahama Bank (LBB) to the periplatform sediment wedge of the northwestern part of the slope over the last 424 ka. The LBB northwestern slope is divided in (i) a plateau-like structure (margin) at similar to 40 m water depth over at least 4 km parallel to the edge of the LBB; (ii) the uppermost slope with a mean slope angle of similar to 1.15 degrees from 40 to 300 m water depth; (iii) the upper, slope with slope angle of similar to 0.7 from 300 to 650 m water depth, (iv) the middle slope with slope angle of similar to 1.2, from 650 to 800 m water depth, and (v) the lower slope with slope angle of -6 m) that occurred during interglacial periods, the highest sedimentation rates (10-30 cm/ka) and the finest sediment fades were found on the slope. During interglacial periods when RSL < -6 m, LBB was emerged but bank margins were still flooded and correspond to intermediate sedimentation rates (a few to 10 cm/ka) on the slope. Finally, during glacial periods (RSL < -90 m), LBB was emerged (including its margins), sedimentation rates on the slope dropped to a few mm/ka associated to coarser sediment facies. Off-bank-transported sediment is the main sediment supply during sea-level highstands, occurring preferentially during three major periods of LBB flooding over the last 424 ka: marine isotopic stages 1, 5e and 11. During sea level lowstands, shallow carbonate production was very low but could develop over a 4 km-wide plateau-like structure when RSL was above -40 m. The regional Antilles Current affected the sea floor along the northwestern LBB slope and influenced coral mound distribution as well as sediment facies and sequences along the upper and middle slopes (300-800 m). During glacial periods, the stronger influence of the Antilles Current upon the along-slope sedimentation promoted diagenesis via the development of indurated nodules in the upper slope (similar to 400 m water depth). It also encouraged bi-gradational sequences showing a coarsening-up unit followed by a fining-up unit along the middle slope (similar to 800 m water depth) that is thoroughly bioturbated. The characteristics of these contourite sequences were similar to those described in siliciclastic environments, but in contrast were condensed with low sedimentation rates over long (glacial) periods. (C) 2015 Elsevier B.V. All rights reserved.

Published
2016

26. On the architecture of intra-formational Mass-Transport Deposits: Insights from the carbonate slopes of Great Bahama Bank and the Apulian Carbonate Platform

Author

Thibault Cavailhes, Thierry Mulder, Emmanuelle Ducassou, Vincent Hanquiez, J. Le Goff, Arnoud Slootman, John J. G. Reijmer, and Jalel Jaballah

Subjects
010504 meteorology & atmospheric sciences, Outcrop, Carbonate platform, Geology, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Sedimentary depositional environment, Tectonics, chemistry.chemical_compound, chemistry, Geochemistry and Petrology, Carbonate, Sedimentary rock, Shear zone, Petrology, Lithification, 0105 earth and related environmental sciences
Abstract

Large sub-tropical carbonate platforms shed huge volumes of sediment onto their adjacent slopes. Resulting carbonate successions are comprised of gravity-flow beds (turbidites, debrites), which are occasionally reworked into mass-transport deposits (MTDs) by the failure of inconsistently lithified portions of slope strata. Despite their significance in the depositional record, the internal architecture of MTDs along relatively tectonically stable and sediment-producing carbonate platforms is poorly understood in comparison with counterparts in active compressional tectonic settings. This study compares carbonate-slope-derived MTDs imaged in seismic reflection data with those observed in outcrop. The internal architecture of MTDs from two case studies is presented: the seismically-imaged MTDs in Miocene-Recent carbonate-slope deposits from the Bahamas, and MTDs off the Cretaceous Apulian carbonate margin exposed in outcrops of the Ionian Basin (Albania). Understanding the large-scale (kilometers to tens of kilometers) internal architecture of MTDs in seismic is crucial for identification of these structures in outcrop. In turn, only outcrop studies allow the detailed analysis of the reworking style within these massive sediment bodies at a smaller scale (meters to kilometers). The internal architecture of the studied carbonate MTDs testifies to the existence of an along-slope continuum of deformation structures, characterized by vertical partitioning into distinct mass flows during single mass-transport events. Mass-wasting processes are inferred from strain-partitioning structures, recording along-slope and slope-parallel architectural heterogeneities. Three deformation domains are recognized: extensional headwall domain, translational body domain, and contractional toe domain. Confined MTDs are limited by steep and deep lateral margins and frontal ramps that mark the boundaries between failed deposits and undisturbed strata. Vertical strain-partitioning is pronounced in the toe domain. Upward intensification of deformation within MTDs is common and corresponds to a top-down reorganization of failed strata during downslope transport. Intra-formational MTDs along carbonate slopes that are lacking exotics, such as the ones studied here, differ from extra-formational MTDs occurring in compressional tectonic settings that form sedimentary melanges. Ductile-layer deformation structures are predominant in carbonate MTDs as opposed to block-in-matrix fabrics in sedimentary melanges. The development of shear surfaces, rather than ductile shear zones, in the body and toe domains presents predictive (in modern environments) and diagnostic criteria (in fossil examples) of mass-wasting events along carbonate slopes.

Published
2020

27. Modern pollen representation of the vegetation of the Tagus Basin (central Iberian Peninsula)

Author

Ludovic Devaux, Vincent Hanquiez, César Morales-Molino, Maria Fernanda Sanchez Goñi, and Muriel Georget

Subjects
Palynology, Mediterranean climate, geography, geography.geographical_feature_category, Ecology, Paleontology, Woodland, Evergreen, medicine.disease_cause, Shrubland, Pollen, Paleoecology, medicine, Dominance (ecology), Ecology, Evolution, Behavior and Systematics
Abstract

The study of modern vegetation–pollen relationships has long been recognized as crucial for the proper interpretation of fossil pollen records. Despite the quickly growing number of palynological studies from central Iberia and its adjacent Atlantic margin, comprehensive studies about modern pollen representation at broad spatial scales were still lacking. In this paper, we have studied the vegetation–pollen relationships in the Tagus Basin in 62 sites located along a wide environmental gradient from Thermomediterranean evergreen mixed thermophilous woodlands by the Atlantic coast to Oromediterranean shrublands above the treeline in the Guadarrama Mountains (central Spain). At each site, we analyzed pollen from moss polsters and conducted vegetation surveys. Most forested vegetation types (pinewoods, oak woods, evergreen mixed thermophilous woodlands) presented rather distinct pollen assemblages dominated by the pollen equivalents of the major tree species. Nevertheless, enhanced taxonomic resolution within Pinus and Quercus ilex-type would represent significant progress, e.g., enabling to separate Mediterranean and mountain pinewoods. Pollen spectra from shrubland and steppic communities are in general less differentiated, due to high regional pollen input associated with low local pollen production and/or the dominance of insect-pollinated species (e.g., Cytisus oromediterraneus in mountain shrublands). The results presented here will readily assist the interpretation of regional fossil pollen records from small mires/bogs/lakes and forest hollows, given their comparable pollen catchments. Comparison of modern pollen assemblages with pollen records from larger lakes and marine settings is not so straightforward, but our results suggest that marine pollen assemblages might average the pollen signature of the entire basin.

Published
2020

28. Genesis and growth of a carbonate Holocene wedge on the northern Little Bahama Bank

Author

Emmanuelle Ducassou, Thierry Mulder, Marie-Claire Perello, Jean Borgomano, Vincent Hanquiez, Emmanuelle Poli, Kelly Fauquembergue, Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), TOTAL-Scientific and Technical Center Jean Féger (CSTJF), TOTAL FINA ELF, Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Collège de France (CdF)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Institut National de la Recherche Agronomique (INRA), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Centre scientifique et Technique Jean Feger (CSTJF), and Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Density cascading, 010504 meteorology & atmospheric sciences, Carbonate platform, Bahamas, Stratigraphy, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, engineering.material, Off-bank transport, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Wedge (geometry), Cold fronts, Paleontology, chemistry.chemical_compound, 14. Life underwater, Meltwater, Holocene, 0105 earth and related environmental sciences, Carbonate slope, Aragonite, Meltwater pulses, Geology, Last Glacial Maximum, Hurricanes, Geophysics, chemistry, 13. Climate action, [SDU]Sciences of the Universe [physics], engineering, Carbonate, Economic Geology, Sedimentary rock
Abstract

International audience; The study focuses on the sedimentary dynamics at the transition between the modern Bahamas carbonate platform and related adjacent slopes and deeper environments. A Holocene carbonate sedimentary wedge is developed at the edge of the carbonate platform extending along the northern Little Bahamas Bank (LBB; Bahamas). The transition area between the platform and the wedge shows superposed terraces. The Holocene wedge thickness varies from 0 to 35 m. Its surface is dominated by homogeneous, fine-grained, soft sediments. It lies on a Pleistocene substratum and fills depressions corresponding to lowstand erosional surfaces. On the uppermost slope, this wedge represents the main depocenter of fine-grained bank-derived sediments since the last bank flooding.Twelve gravity cores were sampled from this wedge and allow the identification of both the processes that can supply this wedge and the wedge evolution based on content analyses and 19 radiocarbon ages.At present, particle export from the LBB margins mostly occurs during episodes of winter cold fronts but also occurs during hurricanes. Evidence of hurricane impact in the sedimentary record is suggested by the recovery of two laminated sequences showing both decreasing sedimentation rates and varying velocities during platform export. The local morphology of the platform edge allows the better sorting and export of sediments according to the presence of tidal outlets and sediment sorting on the wedge. However, because no ooids from tidal deltas located on the platform edge were found in cores, tidal currents are probably not energetic enough to both mobilize and export sediment, even if tide–induced currents may help the export of fine-grained carbonate particles remobilized by either cold fronts or hurricanes on the platform and upper slope.The formation of the wedge started at 13.6 ± 3.5 kyr cal BP following the meltwater pulse 1 A. It was supplied by shallow environment-derived particles produced on four narrow terraces between 60 and 20 mbsl after meltwater pulses. Since the LGM (Last Glacial Maximum), terrace formation seems to correspond to periods of sea-level stillstands and wedge formation, whilst escarpments correspond to periods of high rates of rising sea-level due to meltwater pulses. The main period of wedge growth started around 6.5 ± 0.9 kyr cal BP, when sea level finally reached the platform margins. The maximum flooding period around 4 kyr cal BP is characterized by the highest contents of aragonite needles exported from the platform.

Published
2018

29. Monitoring Topography of Coastal Lagoons Using Satellite Radar Altimetry

Author

Benoit Laignel, Jean-Paul Parisot, Imen Turki, Frédéric Frappart, Vincent Marieu, Edward Salameh, Alexandra Spodar, and Vincent Hanquiez

Subjects
010504 meteorology & atmospheric sciences, 0211 other engineering and technologies, Intertidal zone, 02 engineering and technology, 01 natural sciences, Satellite radar altimetry, Spaceborne radar, Geoid, Altimeter, Orbit determination, Geology, 021101 geological & geomatics engineering, 0105 earth and related environmental sciences, Remote sensing
Abstract

Satellite radar altimetry was initially designed to measure the marine geoid. Thanks to the improvement in the orbit determination from the meter to the centimeter level, this technique has been providing accurate measurements of the sea surface topography over the open ocean since the launch of Topex/Poseidon in 1992. In spite of a decrease in the performance over land and coastal areas, it is now commonly used over these surfaces. This study analyzes the ability of satellite radar altimetry to retrieve for the very first time the topography of the intertidal zone in coastal lagoons.

Published
2018

30. To What Extent Multidecadal Changes in Morphology and Fluvial Discharge Impact Tide in a Convergent (Turbid) Tidal River

Author

Sabine Schmidt, A. Fort, Aldo Sottolichio, Vincent Hanquiez, Isabel Jalón-Rojas, Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), and Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS)

Subjects
geography, Morphology (linguistics), 010504 meteorology & atmospheric sciences, 0208 environmental biotechnology, Fluvial, 02 engineering and technology, Oceanography, 01 natural sciences, 020801 environmental engineering, Geophysics, geography.body_of_water, Space and Planetary Science, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), Tidal river, Regime shift, 14. Life underwater, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Geology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

International audience

Published
2018

31. Dynamics of particulate organic matter composition in coastal systems: Forcing of spatio-temporal variability at multi-systems scale

Author

Philippe Pineau, Aurore Gueux, Martine Bréret, Sophie Ferreira, Muriel Crouvoisier, Cédric Leroux, Pascal Claquin, Francois Dindinaud, Peggy Rimmelin-Maury, Camilla Liénart, Elsa Breton, Gaël Guillou, Pascal Conan, Mireille Pujo-Pay, Patrick Raimbault, Franck Petit, Béatrice Lauga, Emilie Grossteffan, Nicolas Susperregui, Michel Lafont, Paco Rodriguez Tress, Véronique Lagadec, Emmanuelle Sultan, Eric Maria, Pierre-Guy Sauriau, Yann Bozec, Julien Guillaudeau, Jézabel Lamoureux, Sandrine Geslin, Fabien Aubert, Orianne Jolly, Anne-Marie Corre, Nicolas Savoye, Maïa Durozier, Laurence Costes, Eric Feunteun, Sabrina Bichon, Stéphane L'Helguen, Eric Macé, Benoit Lebreton, Nicolas Lachaussée, Christophe Boinet, Valérie David, Vincent Marieu, Laure Mousseau, Jocelyne Caparros, Hervé Derriennic, Yolanda Del Amo, Vanessa Rouaud, Jean-Paul Lehodey, Sébastien Aubin, Robert Duran, Thierry Cariou, Nicole Garcia, Line Bourasseau, Pierre Ramond, Vincent Hanquiez, Eric Lecuyer, Jérémy Devesa, Antoine Nowaczyk, UMR 5805 Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Dynamiques de l'Environnement Côtier (DYNECO), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Environnements et Paléoenvironnements OCéaniques (EPOC), Centre De Recherche et d'Enseignement sur les Systèmes Côtiers (CRESCO), Station marine Dinard, Centre National de la Recherche Scientifique (CNRS), LIttoral ENvironnement et Sociétés - UMRi 7266 (LIENSs), Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS), CHImie Marine (CHIM), Adaptation et diversité en milieu marin (AD2M), Station biologique de Roscoff (SBR), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Station biologique de Roscoff (SBR), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 (LOG), Centre National de la Recherche Scientifique (CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Institut national des sciences de l'Univers (INSU - CNRS), Laboratoire d'Océanographie Microbienne (LOMIC), Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Observatoire océanologique de Banyuls (OOB), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU), Laboratoire d'océanographie de Villefranche (LOV), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de la Mer de Villefranche (IMEV), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Nutrition et Neurobiologie intégrée (NutriNeuro), Université Bordeaux Segalen - Bordeaux 2-Institut National de la Recherche Agronomique (INRA)-Université Sciences et Technologies - Bordeaux 1-Institut Polytechnique de Bordeaux-Ecole nationale supérieure de chimie, biologie et physique, Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux (IPREM), Université de Pau et des Pays de l'Adour (UPPA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Observatoire océanologique de Villefranche-sur-mer (OOVM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'océanographie et de biogéochimie (LOB), Université de la Méditerranée - Aix-Marseille 2-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut méditerranéen d'océanologie (MIO), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Centre de recherches en environnement côtier (CREC), Université de Caen Normandie (UNICAEN), Institut des Milieux Aquatiques, PERMALA-LIGA, funded by the Aquitaine Regional Council, EC2CO-DRIL MOSLIT, Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Dynamiques des Écosystèmes Côtiers (DYNECO), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), LIttoral ENvironnement et Sociétés (LIENSs), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), Adaptation et diversité en milieu marin (ADMM), Institut national des sciences de l'Univers (INSU - CNRS)-Station biologique de Roscoff (SBR), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Station biologique de Roscoff (SBR), Institut national des sciences de l'Univers (INSU - CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Nord]), Observatoire océanologique de Banyuls (OOB), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Fédération de recherche de Roscoff (FR2424), Normandie Université (NU)-Normandie Université (NU)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Université Bordeaux Segalen - Bordeaux 2-Institut National de la Recherche Agronomique (INRA)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut Polytechnique de Bordeaux-Ecole nationale supérieure de chimie, biologie et physique, Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Sorbonne Université (SU)-Université des Antilles (UA)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut de Recherche pour le Développement (IRD), Analytical, Environmental and Geo- Chemistry, Vrije Universiteit [Brussels] (VUB), LIttoral ENvironnement et Sociétés - UMR 7266 (LIENSs), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Station biologique de Roscoff [Roscoff] (SBR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Station biologique de Roscoff [Roscoff] (SBR), Université de Lille-Université du Littoral Côte d'Opale-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Institut Universitaire Européen de la Mer (IUEM), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Université de Brest (UBO)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Nutrition et Neurobiologie intégrée (NutriNeur0), Ecole nationale supérieure de chimie, biologie et physique-Institut Polytechnique de Bordeaux-Université Sciences et Technologies - Bordeaux 1-Institut National de la Recherche Agronomique (INRA)-Université Bordeaux Segalen - Bordeaux 2, Université de Pau et des Pays de l'Adour (UPPA)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire océanologique de Villefranche-sur-mer (OOVM), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Evolution des Systèmes Naturels et Modifiés (LESNM), Muséum national d'Histoire naturelle (MNHN)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), Centre de recherche et d'enseignement des systèmes côtiers (CRESCO), Muséum national d'Histoire naturelle (MNHN), UMS 3113, Institut Universitaire Européen de la Mer (IUEM), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université de Brest (UBO), Qualité des eaux et prévention des pollutions (UR QELY), Centre national du machinisme agricole, du génie rural, des eaux et forêts (CEMAGREF), Centre National de la Recherche Scientifique (CNRS)-Université de Toulon (UTLN)-Aix Marseille Université (AMU)-Institut de Recherche pour le Développement (IRD), Station Marine, Université de Lille, Sciences et Technologies-PRES Université Lille Nord de France-Centre National de la Recherche Scientifique (CNRS), Sorbonne Universités, Centre d'Analyse et d'Intervention Sociologiques (CADIS), École des hautes études en sciences sociales (EHESS)-Centre National de la Recherche Scientifique (CNRS), EMBIO, Centre National de la Recherche Scientifique (CNRS)-Université de Toulon (UTLN)-Aix Marseille Université (AMU)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Université de Toulon (UTLN)-Aix Marseille Université (AMU)-Institut de Recherche pour le Développement (IRD), Laboratoire Biens, Normes, Contrats (LBNC), Avignon Université (AU), Station biologique de Roscoff [Roscoff] (SBR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Station biologique de Roscoff [Roscoff] (SBR), Institut de Recherche pour le Développement (IRD)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université de Pau et des Pays de l'Adour (UPPA), Institut de Recherche pour le Développement (IRD)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Pau et des Pays de l'Adour (UPPA), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS)-Université de Brest (UBO)

Subjects
0106 biological sciences, 010504 meteorology & atmospheric sciences, Environmental forcing, Forcing (mathematics), Aquatic Science, 01 natural sciences, Water column, Particulate organic matter, Phytoplankton, medicine, Coastal systems, 14. Life underwater, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, ComputingMilieux_MISCELLANEOUS, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, Trophic level, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, geography, geography.geographical_feature_category, 010604 marine biology & hydrobiology, ACL, Geology, Estuary, Seasonality, medicine.disease, Meta-analysis, Oceanography, 13. Climate action, Benthic zone, [SDE]Environmental Sciences, Environmental science, Sedimentary rock, France, [SDE.BE]Environmental Sciences/Biodiversity and Ecology
Abstract

International audience; In costal systems, particulate organic matter (POM) results from a multiplicity of sources having their respective dynamics in terms of production, decomposition, transport and burial. The POM pool experiences thus considerable spatial and temporal variability. In order to better understand this variability, the present study employs statistical multivariate analyses to investigate links between POM composition and environmental forcings for a panel of twelve coastal systems distributed along the three maritime regions of France and monitored weekly to monthly for 1 to 8 years.At multi-system scale, two main gradients of POC composition have been identified: a 'Continent-Ocean' gradient associated with hydrodynamics, sedimentary dynamics and depth of the water column, and a gradient of trophic status related to nutrient availability. At local scale, seasonality of POC composition appears to be station-specific but still related to part of the above-mentioned forcings. A typology of systems was established by coupling spatial and temporal variability of POC composition. Four groups were highlighted: (1) the estuarine stations where POC composition is dominated by terrestrial POM and driven by hydrodynamics and sedimentary processes, (2) the oligotrophic systems, characterized by the contribution of diazotrophs due to low nutrient availability, and the marine meso/eutroph systems whose POC composition is (3) either deeply dominated by phytoplankton or (4) dominated by phytoplankton but where the contribution of continental and benthic POC is not negligible and is driven by hydrodynamics, sedimentary processes and the height of the water column.Finally, the present study provides several insights into the different forcings to POM composition and dynamics in temperate coastal systems at local and multi-system scales. This work also presents a methodological approach that establishes statistical links between forcings and POM composition, helping to gain more objectively insight of forcings.

Published
2018

32. Monitoring Sea Level and Topography of Coastal Lagoons Using Satellite Radar Altimetry: The Example of the Arcachon Bay in the Bay of Biscay

Author

Jean-Paul Parisot, Imen Turki, Alexandra Spodar, Vincent Marieu, Frédéric Frappart, Edward Salameh, Benoit Laignel, Vincent Hanquiez, Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Morphodynamique Continentale et Côtière (M2C), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Géosciences Environnement Toulouse (GET), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 (LOG), Centre National de la Recherche Scientifique (CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Institut national des sciences de l'Univers (INSU - CNRS), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), and Institut national des sciences de l'Univers (INSU - CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Nord])

Subjects
010504 meteorology & atmospheric sciences, Science, 0211 other engineering and technologies, topography of the intertidal zone, Intertidal zone, 02 engineering and technology, 01 natural sciences, radar altimetry, coastal altimetry, sea surface height, ERS-2, ENVISAT, SARAL, CryoSat-2, Geoid, 14. Life underwater, Sea level, Radar altimetry, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 021101 geological & geomatics engineering, 0105 earth and related environmental sciences, Pelagic zone, Sea-surface height, Oceanography, General Earth and Planetary Sciences, Orbit determination, Bay, Geology
Abstract

(IF 4.12; Q1); International audience; Radar altimetry was initially designed to measure the marine geoid. Thanks to the improvement in the orbit determination from the meter to the centimeter level, this technique has been providing accurate measurements of the sea surface topography over the open ocean since the launch of Topex/Poseidon in 1992. In spite of a decrease in the performance over land and coastal areas, it is now commonly used over these surfaces. This study presents a semi-automatic method that allows us to discriminate between acquisitions performed at high tides and low tides. The performances of four radar altimetry missions (ERS-2, ENVISAT, SARAL, and CryoSat-2) were analyzed for the retrieval of sea surface height and, for the very first time, of the intertidal zone topography in a coastal lagoon. The study area is the Arcachon Bay located in the Bay of Biscay. The sea level variability of the Arcachon Bay is characterized by a standard deviation of 1.05 m for the records used in this study (2001-2017). Sea surface heights are very well retrieved for SARAL (R~0.99 and RMSE < 0.23 m) and CryoSat-2 (R > 0.93 and RMSE < 0.42 m) missions but also for ENVISAT (R > 0.82 but with a higher RMSE >0.92 m). For the topography of the intertidal zone, very good estimates were also obtained using SARAL (R~0.71) and CryoSat-2 (R~0.79) with RMSE lower than 0.44 m for both missions.

Published
2018

33. Spatial and temporal patterns of shoreline change of a 280-km high-energy disrupted sandy coast from 1950 to 2014: SW France

Author

Benoit Guillot, Eric Chaumillon, Coline Poppeschi, Vincent Marieu, Stéphane Bujan, Vincent Hanquiez, Bruno Castelle, Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), LIttoral ENvironnement et Sociétés - UMRi 7266 (LIENSs), and Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS)

Subjects
High energy, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Aquatic Science, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Coastal dunes, Wave height, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, 14. Life underwater, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, ComputingMilieux_MISCELLANEOUS, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, Shore, geography, geography.geographical_feature_category, Estuary, Inlet, Sea level rise, 13. Climate action, [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, Geology, Accretion (coastal management)
Abstract

A dataset of 15 geo-referenced orthomosaics photos was generated to address long-term shoreline change along approximately 270 km of high-energy sandy coast in SW France between 1950 and 2014. The coast consists of sandy beaches backed by coastal dunes, which are only disrupted by two wide tidal inlets (Arcachon and Maumusson), a wide estuary mouth (Gironde) and a few small wave-dominated inlets and coastal towns. A time and spatially averaged erosion trend of 1.12 m/year is found over 1950–2014, with a local maximum of approximately 11 m/year and a maximum local accretion of approximately 6 m/year, respectively. Maximum shoreline evolutions are observed along coasts adjacent to the inlets and to the estuary mouth, with erosion and accretion alternating over time on the timescale of decades. The two inlet-sandspit systems of Arcachon and Maumusson show a quasi-synchronous behaviour with the two updrift coasts accreting until the 1970s and subsequently eroding since then, which suggests that shoreline change at these locations is controlled by allocyclic mechanisms. Despite sea level rise and the well-established increase in winter wave height over the last decades, there is no capture of significant increase in mean erosion rate. This is hypothesized to be partly the result of relevant coastal dune management works from the 1960s to the 1980s after a long period of coastal dune disrepair during and after the Second World War. This study suggests that long-term shoreline change of high-energy sandy coasts disrupted by inlets and/or estuaries is complex and needs to consider a wide range of parameters including, non-extensively, waves, tides, inlet dynamics, sea level rise, coastal dune management and coastal defences, which challenges the development of reliable long-term coastal evolution numerical models.

Published
2018

34. Carbonate slope morphology revealing a giant submarine canyon (Little Bahama Bank, Bahamas)

Author

André W. Droxler, Gilles Conesa, Jérémy Ragusa, J. Le Goff, Sara Bashah, John J. G. Reijmer, Hervé Gillet, Mélanie Principaud, L. Guiastrennec, N. Fabregas, A. Recouvreur, Stéphane Bujan, D.G. Blank, Thierry Mulder, Vincent Hanquiez, Chloé Seibert, Thibault Cavailhes, Emmanuelle Ducassou, Kelly Fauquembergue, Geology and Geochemistry, Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Collège de France (CdF)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Institut National de la Recherche Agronomique (INRA), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA), and Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Canyon, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Carbonate platform, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Geology, Submarine canyon, Contourite, 010502 geochemistry & geophysics, 01 natural sciences, Paleontology, Blake Plateau, Sediment gravity flow, Siliciclastic, Sedimentary rock, 14. Life underwater, SDG 14 - Life Below Water, Geomorphology, 0105 earth and related environmental sciences
Abstract

International audience; New high-quality multibeam data detail the morphology of the giant 135-km-long Great Abaco Canyon (GAC) located between Little Bahama Bank (LBB, Bahamas) and Blake Plateau. Knickpoints, chutes, and plunge pools mark the canyon main axis, which is parallel to the LBB margin. The canyon head covers a large area but does not represent the main source of the modern sediments. The material supplied through the LBB canyon systems originates below this head, which only shows erosive lineaments related to the pathway of currents running along the seafloor and restricted failure scars. Most of the sediment supply originates from the canyon sides. The northern canyon flank incises the Blake Plateau, which comprises contourites on top of a drowned Cretaceous carbonate platform. These deposits are susceptible to translational slides and form dissymmetric debris accumulations along the northern edge of the canyon. A large tributary drains the Blake Plateau. Two large tributaries connecting the southern flank of the GAC directly to the LBB upper slope form additional sources of sediments. Subbottom profiles suggest the presence of a sedimentary levee on the tributary canyon and of sediment gravity flow deposits. The GAC has been a permanent structure since the drowning of the Cretaceous platform, and its size and morphology are comparable to those of canyons in siliciclastic environments. The orientation of the GAC parallel to large-scale regional tectonic structures suggests a structural control. The size of the observed structures, especially plunge pools at the base of gigantic chutes, is unusual on Earth. The presence of deposits downflow of the pools suggests that the GAC results from or at least is maintained by persistent and sustained submarine gravity flows rather than by retrogressive erosion.

Published
2018

35. Pervasive multidecadal variations in productivity within the Peruvian Upwelling System over the last millennium

Author

Isabelle Billy, Xavier Crosta, Sophie Fleury, Karine Charlier, Thomas Blanz, Vincent Hanquiez, Philippe Martinez, Ralph R Schneider, Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Institut für Geowissenschaften [Kiel], and Christian-Albrechts-Universität zu Kiel (CAU)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Archeology, Global and Planetary Change, Intertropical Convergence Zone, Geology, 15. Life on land, Oxygen minimum zone, Productivity (ecology), [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, 13. Climate action, North Atlantic oscillation, Climatology, Walker circulation, Upwelling, 14. Life underwater, Precipitation, Climate state, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, Ecology, Evolution, Behavior and Systematics
Abstract

There is no agreement on the pluri-decadal expression of El Nino-Southern Oscillation (ENSO) in the Pacific over the last millennium. Marine records from the Peruvian margin indicate humid conditions (El Nino-like mean conditions) over the Little Ice Age, while precipitation records from the eastern equatorial Pacific infer arid conditions (La Nina-like mean conditions) for the same period. We here studied diatom assemblages, nitrogen isotopes, and major and minor elements at the lamination level in three laminated trigger cores located between 11 degrees S and 15 degrees S on the Peruvian shelf within the oxygen minimum zone (OMZ) to reconstruct precipitation and ocean productivity at the multiannual to multidecadal timescales over the last millennium. We respected the sediment structure, thus providing the first records of the mean climatic conditions at the origin of the lamination deposition, which ones represent several years. Light laminations were deposited under productive and dry conditions, indicative of La Nina-like mean conditions in the system, while dark laminations were deposited under non-productive and humid conditions, representative of El Nino-like mean conditions. La Nina-like mean conditions were predominant during the Medieval Warm Period (MWP; 1000-600 years BP) and Current Warm Period (CWP; 150 years BP to present), while El Nino-like mean conditions prevailed over the Little Ice Age (LIA; 600-150 years BP). We provide evidence for persistent multidecadal variations in productivity over the last millennium, which were disconnected from the mean climate state. Multidecadal variability has been stronger over the last 450 years concomitantly to increased variability in the NAO index. Two intervals of strong multidecadal variability were also observed over the MWP, congruent to decreased solar irradiance and increased volcanic activity. (C) 2015 Elsevier Ltd. All rights reserved.

Published
2015

36. Origin and architecture of a Mass Transport Complex on the northwest slope of Little Bahama Bank (Bahamas): Relations between off-bank transport, bottom current sedimentation and submarine landslides

Author

Jean Borgomano, Emmanuelle Ducassou, Hervé Gillet, E. Tournadour, Vincent Hanquiez, and Thierry Mulder

Subjects
Stratigraphy, Front (oceanography), Sediment, Geology, Sedimentary rock, Sedimentation, Fault scarp, Geomorphology, Seafloor spreading, Deposition (geology), Submarine landslide
Abstract

The analysis of the sedimentary dynamics of the carbonate slope of the northwest part of Little Bahama Bank (LBB, Bahamas) reveals a complex interaction between slope destabilisations, off-bank sediment export and longitudinal transport, the latter being driven by the Antilles and the Florida currents, at the northern end of the Florida Strait. Their combined action since the middle Miocene resulted in an extensional growth slope, previously called ‘LBB Drift’ (Mullins et al., 1980). Deposition within this extensional growth slope is dominated by either platform-derived downslope sedimentation or bottom current sedimentation. The latter induces the formation of a plastered drift, showing both upslope and downslope migrations, which do not correspond to the ‘LBB Drift’ as described by Mullins et al. (1980). Interestingly, a large submarine landslide affects the upper part of this plastered drift, and displays a complex and striking geomorphology on the seafloor. A new high-quality multibeam echosounder and seismic dataset allowed a detailed characterisation of the architecture of this Mass Transport Complex (MTC). A 44 km-long circular incision at 275 m and 460 m water depths, with a steep external edge (from 40 to 70 m high), forms the only present day evidence of this ancient MTC. It comprises confined Mass Transport Deposits (MTDs), which are delimited by frontal and lateral edges that developed inside the plastered drift. The top of this plastered drift is marked by a major erosional surface, most likely induced by an increase in oceanic current circulation. Channelised geometries, laterally associated with overspill deposits, developed within the depression induced by the MTC, and are an additional evidence of bottom current activity in this area. In addition, recent pockmarks are visible on the seafloor in front of the circular scarp of the MTC and probably relate to fluid escape, originating from the underlying MTDs' compressional area. All these features seen on the northwest slope of LBB bring new understanding on MTC sedimentary processes and associated morphologies in carbonate slope settings. Furthermore, this study highlights the interplay between off-bank transport, oceanic circulation and mass flow processes, which are seen as key processes in the shaping of Bahamian slopes and in their sedimentary dynamics.

Published
2015

37. Dynamics of particulate organic matter composition in coastal systems: a spatio-temporal study at multi-systems scale

Author

Francois Dindinaud, Michel Lafont, Aurore Gueux, Benoit Lebreton, Christophe Boinet, Vincent Cornille, Gaël Guillou, Jocelyne Caparros, Martine Bréret, Jean-Paul Lehodey, Julien Guillaudeau, Pierre Richard, Fabien Aubert, Sabrina Bichon, Stéphane L'Helguen, Fabrice Garcia, Eric Maria, Laurence Costes, Yolanda Del Amo, Eric Macé, Nicolas Lachaussée, Sandrine Geslin, Pascal Riera, Gauthier Schaal, Elsa Breton, Emilie Grossteffan, Valérie David, Laure Mousseau, Emmanuelle Sultan, Pierre-Guy Sauriau, Karine Grangeré, Nicolas Savoye, Maïa Durozier, Nicole Garcia, Line Bourasseau, Eric Lecuyer, Olivier Crispi, Pascal Claquin, Michel Fornier, David Lemeille, Yann Bozec, Philippe Kerhervé, Franck Petit, Mireille Pujo-Pay, Cédric Leroux, Anne-Marie Corre, Marie Czamanski, Antoine Nowaczyk, Jérémy Devesa, Karine Charlier, Jézabel Lamoureux, Orianne Joly, Hervé Derriennic, Sébastien Aubin, Thierry Cariou, Peggy Rimelin-Maury, Vincent Hanquiez, Sébastien Lefebvre, Camilla Liénart, Patrick Raimbault, Eric Feunteun, Philippe Pineau, Sophie Ferreira, Muriel Crouvoisier, Pascal Conan, Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), CHImie Marine (CHIM), Adaptation et diversité en milieu marin (ADMM), Institut national des sciences de l'Univers (INSU - CNRS)-Station biologique de Roscoff (SBR), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Station biologique de Roscoff (SBR), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 (LOG), Institut national des sciences de l'Univers (INSU - CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Nord]), Université du Littoral Côte d'Opale (ULCO), Laboratoire d'Océanographie Microbienne (LOMIC), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Observatoire océanologique de Banyuls (OOB), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre De Recherche et d'Enseignement sur les Systèmes Côtiers (CRESCO), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Station marine Dinard, Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Centre de Formation et de Recherche sur les Environnements Méditérranéens (CEFREM), Université de Perpignan Via Domitia (UPVD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), LIttoral ENvironnement et Sociétés (LIENSs), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'océanographie de Villefranche (LOV), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de la Mer de Villefranche (IMEV), Institut méditerranéen d'océanologie (MIO), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Ecogéochimie et Fonctionnement des Ecosystèmes Benthiques (EFEB), Muséum national d'Histoire naturelle (MNHN), Station biologique de Roscoff (SBR), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Fédération de recherche de Roscoff (FR2424), Observatoire océanologique de Villefranche-sur-mer (OOVM), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre de recherches en environnement côtier (CREC), Normandie Université (NU)-Normandie Université (NU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Adaptation et diversité en milieu marin (AD2M), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Station biologique de Roscoff (SBR), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire océanologique de Banyuls (OOB), Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Université de Caen Normandie (UNICAEN), Centre National de la Recherche Scientifique (CNRS), Université de Perpignan Via Domitia (UPVD)-Centre National de la Recherche Scientifique (CNRS), LIttoral ENvironnement et Sociétés - UMRi 7266 (LIENSs), Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Toulon (UTLN), UMR 5805 Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Sorbonne Université (SU)-Université des Antilles (UA)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut de Recherche pour le Développement (IRD), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Station biologique de Roscoff [Roscoff] (SBR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Station biologique de Roscoff [Roscoff] (SBR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université de Lille-Université du Littoral Côte d'Opale-Centre National de la Recherche Scientifique (CNRS), Observatoire océanologique de Banyuls (OOB), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), LIttoral ENvironnement et Sociétés - UMR 7266 (LIENSs), Centre de recherche et d'enseignement des systèmes côtiers (CRESCO), Harte Research Institute for Gulf of Mexico Studies, Texas A&M University [Corpus Christi], Institut de Recherche pour le Développement (IRD)-Institut Universitaire Européen de la Mer (IUEM), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Université de Brest (UBO)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire océanologique de Villefranche-sur-mer (OOVM), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université de Toulon (UTLN)-Aix Marseille Université (AMU)-Institut de Recherche pour le Développement (IRD), ESEO-GSII (GSII), ESEO-Tech, Université Bretagne Loire (UBL)-Université Bretagne Loire (UBL), CNRS 5320, Centre de Recherche Paul Pascal (CRPP), Université de Bordeaux (UB)-Centre National de la Recherche Scientifique (CNRS), Station biologique de Roscoff [Roscoff] (SBR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Nutrition et Neurobiologie intégrée (NutriNeur0), Ecole nationale supérieure de chimie, biologie et physique-Institut Polytechnique de Bordeaux-Université Sciences et Technologies - Bordeaux 1-Institut National de la Recherche Agronomique (INRA)-Université Bordeaux Segalen - Bordeaux 2, Observatoire Volcanologique et Sismologique de Guadeloupe (OVSG), Institut de Physique du Globe de Paris, Institut de Biologie Intégrative de la Cellule (I2BC), Université Paris-Sud - Paris 11 (UP11)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Saclay, Université de Brest (UBO), EMBIO, Centre National de la Recherche Scientifique (CNRS)-Université de Toulon (UTLN)-Aix Marseille Université (AMU)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Université de Toulon (UTLN)-Aix Marseille Université (AMU)-Institut de Recherche pour le Développement (IRD), UMS 3113, Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université de Brest (UBO), Biologie des écosystèmes aquatiques (UR BELY), Centre national du machinisme agricole, du génie rural, des eaux et forêts (CEMAGREF), Normandie Université (NU), Centre Émile Durkheim (CED), Centre National de la Recherche Scientifique (CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Institut national des sciences de l'Univers (INSU - CNRS), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS)-Université de Brest (UBO), Biologie des Organismes et Ecosystèmes Aquatiques ( BOREA ), Université des Antilles ( UA ) -Université de Caen Normandie ( UNICAEN ), Normandie Université ( NU ) -Normandie Université ( NU ) -Institut de Recherche pour le Développement ( IRD ) -Muséum National d'Histoire Naturelle ( MNHN ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Centre National de la Recherche Scientifique ( CNRS ), Environnements et Paléoenvironnements OCéaniques ( EPOC ), Observatoire aquitain des sciences de l'univers ( OASU ), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -École pratique des hautes études ( EPHE ) -Centre National de la Recherche Scientifique ( CNRS ), CHImie Marine ( CHIM ), Adaptation et diversité en milieu marin ( ADMM ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 ( LOG ), Université du Littoral Côte d'Opale-Université de Lille-Centre National de la Recherche Scientifique ( CNRS ), Laboratoire d'Océanographie Microbienne ( LOMIC ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Centre National de la Recherche Scientifique ( CNRS ), LIttoral ENvironnement et Sociétés - UMR 7266 ( LIENSs ), Université de La Rochelle ( ULR ) -Centre National de la Recherche Scientifique ( CNRS ), Centre de recherche et d'enseignement des systèmes côtiers ( CRESCO ), Muséum National d'Histoire Naturelle ( MNHN ), Centre de Formation et de Recherche sur les Environnements Méditérranéens ( CEFREM ), Université de Perpignan Via Domitia ( UPVD ) -Centre National de la Recherche Scientifique ( CNRS ), Harte Research Institute for Gulf of Mexico Studies, Texas A&M University – Corpus Christi, Rongeurs Sauvages – Risques Sanitaires et Gestion des Populations, INRA, VetAgro Sup ( USC1233/RS2GP ), Institut National de la Recherche Agronomique ( INRA ) -VetAgro Sup ( VAS ), Laboratoire des Sciences de l'Environnement Marin (LEMAR) ( LEMAR ), Centre National de la Recherche Scientifique ( CNRS ) -Université de Brest ( UBO ) -Institut Français de Recherche pour l'Exploitation de la Mer ( IFREMER ) -Institut Universitaire Européen de la Mer ( IUEM ), Institut de Recherche pour le Développement ( IRD ) -Université de Brest ( UBO ) -Centre National de la Recherche Scientifique ( CNRS ) -Institut de Recherche pour le Développement ( IRD ) -Université de Brest ( UBO ) -Centre National de la Recherche Scientifique ( CNRS ) -Institut de Recherche pour le Développement ( IRD ), Laboratoire d'océanographie de Villefranche ( LOV ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Institut méditerranéen d'océanologie ( MIO ), Institut de Recherche pour le Développement ( IRD ) -Aix Marseille Université ( AMU ) -Université de Toulon ( UTLN ) -Centre National de la Recherche Scientifique ( CNRS ), Ecogéochimie et Fonctionnement des Ecosystèmes Benthiques ( EFEB ), ESEO-GSII ( GSII ), PRES Université Nantes Angers Le Mans ( UNAM ) -PRES Université Nantes Angers Le Mans ( UNAM ), Centre de recherche Paul Pascal, CNRS, Université de Bordeaux ( UPR8641 ), Centre de Recherche Paul Pascal, CNRS, Université de Bordeaux, Centre National de la Recherche Scientifique ( CNRS ), UMR 5805 Environnements et Paléoenvironnements Océaniques et Continentaux ( EPOC ), Station biologique de Roscoff [Roscoff] ( SBR ), Nutrition et Neurobiologie intégrée ( NutriNeur0 ), Université Bordeaux Segalen - Bordeaux 2-Institut National de la Recherche Agronomique ( INRA ) -Université Sciences et Technologies - Bordeaux 1-Institut Polytechnique de Bordeaux-Ecole nationale supérieure de chimie, biologie et physique, OVSG-IPGP, Observatoire Volcanologique et sismologique de la Soufrière de Guadeloupe, Institut de Biologie Intégrative de la Cellule ( I2BC ), Université Paris-Sud - Paris 11 ( UP11 ) -Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay-Centre National de la Recherche Scientifique ( CNRS ), Université de Brest ( UBO ), Institut de Recherche pour le Développement ( IRD ) -Aix Marseille Université ( AMU ) -Université de Toulon ( UTLN ) -Centre National de la Recherche Scientifique ( CNRS ) -Institut de Recherche pour le Développement ( IRD ) -Aix Marseille Université ( AMU ) -Université de Toulon ( UTLN ) -Centre National de la Recherche Scientifique ( CNRS ), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Institut Universitaire Européen de la Mer ( IUEM ), Institut de Recherche pour le Développement ( IRD ) -Université de Brest ( UBO ) -Centre National de la Recherche Scientifique ( CNRS ) -Institut de Recherche pour le Développement ( IRD ) -Université de Brest ( UBO ) -Centre National de la Recherche Scientifique ( CNRS ), Centre de recherches en environnement côtier ( CREC ), Université de Caen Normandie ( UNICAEN ), Normandie Université ( NU ) -Normandie Université ( NU ), Biologie des écosystèmes aquatiques ( UR BELY ), CEMAGREF, Normandie Université ( NU ), Centre Émile Durkheim ( CED ), and Université de Bordeaux ( UB ) -Sciences Po-Centre National de la Recherche Scientifique ( CNRS )

Subjects
0106 biological sciences, Mediterranean climate, 010504 meteorology & atmospheric sciences, chibido, Mixing model, Aquatic Science, 01 natural sciences, coastal systems, N ratio [C], C:N ratio, Water column, Particulate organic matter, Phytoplankton, Littoral zone, medicine, Coastal systems, Organic matter, 14. Life underwater, particulate organic matter, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, chemistry.chemical_classification, [ SDE.BE ] Environmental Sciences/Biodiversity and Ecology, geography, geography.geographical_feature_category, C and N stable isotopes, 010604 marine biology & hydrobiology, ACL, Geology, Estuary, Seasonality, mixing model, medicine.disease, meta-analysis, Oceanography, chemistry, 13. Climate action, Benthic zone, Environmental science, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, france
Abstract

International audience; In coastal systems, the multiplicity of sources fueling the pool of particulate organic matter (POM) leads to divergent estimations of POM composition. Eleven systems (two littoral systems, eight embayments and semi-enclosed systems and one estuary) distributed along the three maritime façades of France were studied for two to eight years in order to quantify the relative contribution of organic matter sources to the surface-water POM pool in coastal systems. This study was based on carbon and nitrogen elemental and isotopic ratios, used for running mixing models. The POM of the estuary is dominated by terrestrial material (93% on average), whereas the POM of the other systems is dominated by phytoplankton (84% on average). Nevertheless, for the latter systems, the POM composition varies in space, with 1) systems where POM is highly composed of phytoplankton (≥ 93%), 2) systems characterized by a non-negligible contribution of benthic (8 to 19%) and/or riverine (7 to 19%) sources, and 3) the Mediterranean systems characterized by the contribution of diazotroph organisms (ca. 14%). A continent-to-ocean gradient of riverine and/or benthic POM contribution is observed. Finally, time series reveal 1) seasonal variations of POM composition, 2) differences in seasonality between systems, and 3) an inshore-offshore gradient of seasonality within each system that were sampled at several stations. Spatial and seasonal patterns of POM composition are mainly due to local to regional processes such as hydrodynamics and sedimentary hydrodynamic (e.g. resuspension processes, changes in river flows, wind patterns influencing along-shore currents) but also due to the geomorphology of the systems (depth of the water column, distance to the shore). Future studies investigating the link between these forcings and POM composition would help to better understand the dynamics of POM composition in coastal systems.

Published
2017

38. Submarine canyon morphologies and evolution in modern carbonate settings: The northern slope of Little Bahama Bank, Bahamas

Author

Jean Borgomano, E. Tournadour, Hervé Gillet, Ludivine Chabaud, Emmanuelle Ducassou, Thierry Mulder, Vincent Hanquiez, Samuel Etienne, Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Collège de France (CdF)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Institut National de la Recherche Agronomique (INRA), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA), and Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Canyon, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Submarine, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Geology, Submarine canyon, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Sedimentary depositional environment, chemistry.chemical_compound, Echo sounding, chemistry, Geochemistry and Petrology, Carbonate, Bathymetry, 14. Life underwater, Levee, Geomorphology, 0105 earth and related environmental sciences
Abstract

International audience; The recent high-quality multibeam echosounder swath bathymetry data and very high-resolution seismic profiles collected along the northern slope of Little Bahama Bank (LBB, Bahamas) constitute a unique dataset that can be used to investigate submarine canyon morphologies in modern carbonate settings. This region represents one of the few examples of submarine canyons that have developed in a purely carbonate system around the world. Our study reveals that there are 18 submarine canyons within the survey area that incise the slope between water depths of 450 m and 1000 m. Morpho-sedimentary analyses allow us to characterise their geometry and spatial distribution and to interpret their formation and control parameters. Among these canyons we distinguish four types: the amphitheatre-shaped canyons (1), canyons with up-dip linear incisions (2), canyons with internal recent depositional geometries, including levees and aggrading terraces on the side of their talweg (3) and canyons that are partially to completely filled (4). Based on these new morphological and geometrical classifications, the distributions of canyon morphologies and the integration of the full dataset, we propose a model for the formation and evolution of carbonate canyons. The latter emphasises that canyon initiation is solely the result of slope failures, which subsequently evolve into proper canyons through two successive phases of retrogressive erosion processes that are controlled by a downslope submarine cementation gradient. The first phase of retrogressive erosion produces widened canyon shapes at water depths of up to 600 m, whereas the second phase forms up dip-propagating linear incisions at water depths of up to 450 m. These linear incisions, which are located 5 to 10 km away from the platform edge, favour the funnelling of sediment fluxes originating from the platform. Subsequently or contemporaneously with this retrogressive erosion, muddy gravity flows are responsible for canyon-fills and the formation of levees and aggrading terraces, which will eventually lead to the complete infill of the canyons, marking the end of an ``erosion-fill'' cycle. On a larger scale, the persistence of such canyons on the slope of LBB is of particular interest, as these are considered to be an exception along the present-day accretionary Bahamian slopes. Although similar canyons have been identified along the western slope of Great Bahama Bank (GBB), today these are totally buried, unlike those of LBB. We therefore suggest that the persistence of LBB canyons may be the result of relatively low sedimentation rates linked with the windward orientation of the platform. This low sedimentation rate has prevented the burial of these canyons since the Pliocene.

Published
2017

39. Impact of explosive volcanic eruptions on the main climate variability modes

Author

Didier Swingedouw, Myriam Khodri, Martin Ménégoz, Juliette Mignot, Pablo Ortega, Christophe Cassou, Vincent Hanquiez, Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Climate and Environmental Physics [Bern] (CEP), Physikalisches Institut [Bern], Universität Bern [Bern] (UNIBE)-Universität Bern [Bern] (UNIBE), Oeschger Centre for Climate Change Research (OCCR), University of Bern, Processus de la variabilité climatique tropicale et impacts (PARVATI), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), NCAS-Climate [Reading], Department of Meteorology [Reading], University of Reading (UOR)-University of Reading (UOR), Barcelona Supercomputing Center - Centro Nacional de Supercomputacion (BSC - CNS), Centre Européen de Recherche et de Formation Avancée en Calcul Scientifique (CERFACS), Barcelona Supercomputing Center, Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Universität Bern [Bern]-Universität Bern [Bern], Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), CERFACS [Toulouse], and Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Desenvolupament humà i sostenible::Medi ambient [Àrees temàtiques de la UPC], 010504 meteorology & atmospheric sciences, Radiative forcing, Climate change, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], 010502 geochemistry & geophysics, Oceanography, Atmospheric sciences, 01 natural sciences, Climate models, Climate predictability, Atlantic multidecadal oscillation, Erupcions volcàniques, Volcanic eruptions, ComputingMilieux_MISCELLANEOUS, Detectors de radiació, 0105 earth and related environmental sciences, Global and Planetary Change, Explosive eruption, Climate oscillation, 13. Climate action, North Atlantic oscillation, Climatology, Climate model, Climate state, Geology
Abstract

Volcanic eruptions eject largeamounts of materials into the atmosphere, which can have an impact on climate. In particular, the sulphur dioxide gas released in the stratosphere leads to aerosol formation that reflects part of the incoming solar radiation, thereby affecting the climate energy balance. In this review paper, we analyse the regional climate imprints of large tropical volcanic explosive eruptions. For this purpose, we focus on the impact on three major climatic modes, located in the Atlantic (the North Atlantic Oscillation: NAO and the Atlantic Multidecadal Oscillation: AMO) and Pacific (the El Niño Southern Oscillation, ENSO) sectors. We present an overview of the chain of events that contributes to modifying the temporal variability of these modes. Our literature review is complemented by new analyses based on observations of the instrumental era as well as on available proxy records and climate model simulations that cover the last millennium. We show that the impact of volcanic eruptions of the same magnitude or weaker than 1991 Mt. Pinatubo eruption on the NAO and ENSO is hard to detect, due to the noise from natural climate variability. There is however a clear impact of the direct radiative forcing resulting from tropical eruptions on the AMO index both in reconstructions and climate model simulations of the last millennium, while the impact on the ocean circulation remains model-dependent. To increase the signal to noise ratio and better evaluate the climate response to volcanic eruptions, improved reconstructions of these climatic modes and of the radiative effect of volcanic eruptions are required on a longer time frame than the instrumental era. Finally, we evaluate climate models' capabilities to reproduce the observed and anticipated impacts and mechanisms associated with volcanic forcing, and assess their potential for seasonal to decadal prediction. We find a very large spread in the simulated responses across the different climate models. Dedicated experimental designs and analyses are therefore needed to decipher the cause for this large uncertainty. This research was partly funded by the ANR MORDICUS project (ANR-13-SENV-0002-02). It is also funded by the SPECS project funded by the European Commission's Seventh Framework Research Programme under the grant agreement 308378 and by the EMBRACE project with research number 282672. To analyse the CMIP5 data, this study benefited from the IPSL Prodiguer-Ciclad facility, which is supported by CNRS, UPMC, Labex L-IPSL, which is funded by the ANR (grant # ANR-10-LABX-0018) and by the European FP7 IS-ENES2 project (grant # 312979). The research leading to these results has received funding from the Ministerio de Economía y Competitividad (MINECO) as part of the VOLCADEC project CGL2015-70177-R. We also thank Patrick Brockmann for help with the figure design and Eric Guilyardi for useful insights on the section dealing with ENSO. Finally, we acknowledge the comments from two reviewers that helped to clarify our arguments and complete the paper with some useful references.

Published
2017

40. First Discovery of Channel-Levee Complexes In A Modern Deep-Water Carbonate Slope Environment

Author

Pascal Kindler, François Fournier, Ludivine Chabaud, Mélanie Principaud, Hervé Gillet, Jean Borgomano, Vincent Hanquiez, Philippe Léonide, Thierry Mulder, Isabelle Billeaud, Emmanuelle Ducassou, Eliane Gonthier, and Gregor P. Eberli

Subjects
geography, geography.geographical_feature_category, Geochemistry, Geology, Turbidite, Deep water, chemistry.chemical_compound, chemistry, Erosion, Carbonate, Siliciclastic, Levee, Hydrocarbon exploration, Geomorphology, Channel (geography)
Abstract

New high-quality high-resolution seismic data along the western slope of the Great Bahama Bank reveals a present-day channel–levee complex developed in a pure carbonate setting. This complex grew over two buried complexes separated by erosion surfaces, suggesting both the continuity of downslope gravity-driven processes along this carbonate slope, and channel migration through avulsion, processes similar to what happens along siliciclastic slopes. Complex morphology and geometry are similar to analogs described in siliciclastic systems, but the size of the presented carbonate complex is smaller by a factor of ten. Integrating high-resolution seismic and core studies shows that this complex was built by the stacking of gravity-flow deposits, including turbidites. It presently is inactive and buried by deposits from hemipelagic fallout or low-energy density processes channeled by the gully network; Recent sediments are reworked by along-slope bottom currents dominated by internal tides. The discovery of these channel–levee complexes has implications both on the conceptual models describing the behavior of carbonate slope systems and on hydrocarbon exploration by enhancing the reservoir-bearing potential of carbonate slopes.

Published
2014

41. Application of the European Water Framework Directive: Identification of reference sites and bioindicator fish species for mercury in tropical freshwater ecosystems (French Guiana)

Author

Régis Vigouroux, Sophie Gentès, Marina Coquery, Régine Maury-Brachet, Vincent Hanquiez, and Luc Allard

Subjects
0106 biological sciences, Ecology, biology, General Decision Sciences, 010501 environmental sciences, 15. Life on land, biology.organism_classification, 010603 evolutionary biology, 01 natural sciences, Freshwater ecosystem, 6. Clean water, Water Framework Directive, 13. Climate action, Indicator species, Environmental science, 14. Life underwater, Hoplias aimara, Water quality, Gymnotus, Bioindicator, Ecology, Evolution, Behavior and Systematics, Moenkhausia, 0105 earth and related environmental sciences
Abstract

Mercury (Hg) is a toxic metal subject to several international regulations. The European Water Framework Directive (WFD) established in 2008 an Environmental Quality Standard for biota (EQSbiota) at 0.02 µg.g−1 fresh weight. This standard is not always adapted, such as in French Guiana subjected to high natural background Hg levels and intensive illegal gold mining. Therefore, this study focuses on how to apply the WFD for the definition of good chemical status (i.e., EQSbiota) in a context of strong and generalized natural and anthropic Hg contamination. Based on Hg concentrations measured in 6208 fish over >200 sites between 2004 and 2015, we first aimed at discriminating the natural or anthropogenic influences at each site. Then, as WFD recommends considering only high trophic level fish species as bioindicator species, we selected carnivorous/piscivorous fish species able to significantly accumulate Hg and discriminate reference sites from gold mining polluted sites. Total Hg concentrations measured in fish muscle were mostly above the EQSbiota (100% for creeks and 84% for rivers), confirming the unsuitability of the direct application of this standard in French Guiana. Among the studied sites, few potential reference sites were identified: eight sites spread over six different watersheds for creeks, and only two areas (group of sites) both on the Oyapock watershed for rivers. Several relevant bioindicators fish species are proposed: ten species (over 35 species tested) belonging to seven genera on creeks (Moenkhausia oligolepis, Gymnotus carapo, Sternopygus macrurus, Jupiaba [abramoides + keithi], Pimelodella [cristata + geryi + macturki], Copella carsevennensis, Pyrrhulina filamentosa.), and four species (over 21 species tested) belonging to three genera on rivers (Acestrorhyncus [micropelis + falcatus], Hoplias aimara, Ageneiosus inermis). In order to facilitate field sampling, difficult in such remote hydrosystems, and to improve results interpretation, we tested the possibility to group some of these species. Our results indicate that only Jupiaba, Moenkhausia, Pimelodella and Pyrrhulina on creeks could be grouped; and the three bioindicators species proposed on rivers could be pooled. Finally, this work proposes in situ-based reference Hg concentrations for selected bioindicator fish species from French Guiana as an alternative to detect Hg-impacted sites and help the application of the WFD in tropical systems.

Published
2019

42. Contourites in the Gulf of Cadiz: a cautionary note on potentially ambiguous indicators of bottom current velocity

Author

Eliane Gonthier, Elodie Marchès, Samuel Toucanne, Emmanuelle Ducassou, Vincent Hanquiez, Rim Hassan, Thierry Mulder, and Sébastien Zaragosi

Subjects
geography, Mass transport, geography.geographical_feature_category, Continental shelf, Current velocity, Contourite, Environmental Science (miscellaneous), Geotechnical Engineering and Engineering Geology, Oceanography, Sedimentary depositional environment, Paleontology, Clastic rock, Facies, Earth and Planetary Sciences (miscellaneous), Outflow, Geology
Abstract

Facies associations in cores collected in the deep part of the Gulf of Cadiz, which is under the influence of the lower branch of the Mediterranean Outflow Water, are investigated in terms of the classical contourite model using grain-size analyses and thin sections of indurated sediment. Cores include both low-energy (contourite drift) and high-energy (channel) environments. The thin sections and grain-size distributions show that clayey fine silts and sandy coarse silts are the most common facies associations in the studied contourite sequences, while coarse-grained, gravelly contourites are less common. Grain-size distributions are unimodal in the fine-grained and bi- or trimodal in the coarser-grained contourites. This change in grain-size composition is related both to the partial removal of the fine-grained fraction and to the replenishment of the coarser-grained one. In addition, most of the contacts between individual facies are sharp rather than transitional. This suggests that the contourite sequence is only in part related to changes in bottom current velocity and flow competency, but may also be related to the supply of a coarser terrigeneous particle stock, provided by either increased erosion of indurated mud along the flanks of confined contourite channels (mud clasts), or by increased sediment supply by rivers (quartz grains) and downslope mass transport on the continental shelf and upper slope. The classical contourite facies association may therefore not be solely controlled by current velocity, but may be the product of a variety of depositional histories. The classical contourite depositional sequence should therefore be interpreted with greater care and in the light of the regional sedimentological background. In addition, the wisdom of exclusively using mean or modal particle size for the interpretation of depositional contourite processes is questioned. Instead, it is proposed that the vertical evolution of grain-size populations in the facies successions forming contourite sequences be assessed.

Published
2013

43. Morphological evolution of Cap Lopez Canyon (Gabon): Illustration of lateral migration processes of a submarine canyon

Author

Jean-Pierre Crespin, Laurie Biscara, Eric Braccini, Thierry Garlan, Vincent Hanquiez, Thierry Mulder, and Vincent Marieu

Subjects
Canyon, geography, geography.geographical_feature_category, Geology, Submarine canyon, Sinuosity, Oceanography, Thalweg, Headward erosion, Longshore drift, Geochemistry and Petrology, Overbank, Erosion, Geomorphology
Abstract

Comparison of bathymetric data on short time scales (1959–2008) is used to provide new insights into the modern sedimentary dynamics of the Cap Lopez Canyon (Gabon, West Africa). The canyon head evolution is characterized by a north–eastward lateral migration of ~ 180 m between 1959 and 2008. The evolution of the coastline position over the same period highlights the strong relationship between the probable increase of the longshore transport, related to the smoothing of the coast and the morphological evolution of the canyon head. Lateral migration of the thalweg from the inner bend to the outer bend is estimated between 77 and 190 m (or between 1.6 and 3.8 m/year), leading to an increase of the sinuosity (from 1–1.5 in 1959 to 1.3–3.6 in 2008). The migration of the thalweg is associated with strong erosion on the outer bends (up to 60 m) and sediment deposition on the inner bends (up to 25 m). Both the absence of overbank deposits and the developing point-bar morphology may reflect that equilibrium flows are the most frequent flows encountered in the Cap Lopez Canyon. Although erosion of the outer bends is the result of slope failures and steady erosional processes, our study suggests that erosion related to the transit of sediment gravity flows would be the predominant process.

Published
2013

44. Evaluation of the recent morphological evolution of the Gironde estuary through the use of some preliminary synthetic indicators

Author

Olivier Weber, Helene Périnotto, Vincent Hanquiez, Laurie Sabouraud, and Aldo Sottolichio

Subjects
Water mass, geography.geographical_feature_category, Ecology, Intertidal zone, Sediment, Fluvial, Context (language use), Estuary, Geography, Oceanography, Water Framework Directive, Streamflow, Earth-Surface Processes, Water Science and Technology
Abstract

Sottolichio, A., Hanquiez, V., Perinotto, H., Sabouraud, L. and Weber, O., 2013. Evaluation of the recent morphological evolution of the Gironde estuary through the use of some preliminary synthetic indicators. In: Conley, D.C., Masselink, G., Russell, P.E. and O’Hare, T.J. (eds.), Proceedings 12 th International Coastal Symposium (Plymouth, England), Journal of Coastal Research, Special Issue No. 65, pp. 1224-1229, ISSN 0749-0208. Drastic evolution of the physical coastal environment are expected in the future under the effect of climate change. They make necessary to better understand the past morphology evolution, especially considering areas that are the habitat for some specific ecosystems. Moreover, because the context of the water framework directive (WFD), EU members need to generate indicators to evaluate the status of estuarine water masses. To satisfy these two obectives, the recent evolution of the Gironde estuary has been studied by the analysis of bathymetry with GIS. The Gironde is the largest estuary of western Europe, and one of the most turbid. In this study, the analysis extents from 1962 to 1994. Results show that the zone of maximum volume of deposited sediment has migrated continuously towards the upstream portion of the estuary, which is coherent with the decrease of summer river flow and the upstream shift of the turbidity maximum toward the riverine sections. In addition, zones with relative stable and unstable morphology were identified, showing rythmic distribution similarly to those previously recognized through the evolution over 160 years (18251984). This seems to be independent from the fluvial regime, but rather related to the interaction between tidal cooscillations and estuarine morphology, which is not elucidated yet. Finally, some hydro-morpho-sediemntary (HMS) indicators useful to the WFD have been described : distribution of depths, changes on cross section areas, changes of intertidal areas. They are discussed to discriminate the “natural” and “anthropogenic” contribution to morphological changes observed.

Published
2013

45. A survey of the summer coccolithophore community in the western Barents Sea

Author

Ludovic Devaux, Thierry Garlan, Hélène Howa, Vivien Hulot, Vincent Hanquiez, Jacques Giraudeau, Bio-Indicateurs Actuels et Fossiles (BIAF), Université d'Angers (UA), Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Energy Efficient Computing ArchItectures with Embedded Reconfigurable Resources (CAIRN), Inria Rennes – Bretagne Atlantique, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-ARCHITECTURE (IRISA-D3), Institut de Recherche en Informatique et Systèmes Aléatoires (IRISA), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Bretagne Sud (UBS)-École normale supérieure - Rennes (ENS Rennes)-Institut National de Recherche en Informatique et en Automatique (Inria)-Télécom Bretagne-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Bretagne Sud (UBS)-École normale supérieure - Rennes (ENS Rennes)-Institut National de Recherche en Informatique et en Automatique (Inria)-Télécom Bretagne-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche en Informatique et Systèmes Aléatoires (IRISA), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Bretagne Sud (UBS)-École normale supérieure - Rennes (ENS Rennes)-Télécom Bretagne-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Établissement principal du Service hydrographique et océanographique de la Marine (EPSHOM), EPSHOM, UMR 5805 Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), CentraleSupélec-Télécom Bretagne-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National de Recherche en Informatique et en Automatique (Inria)-École normale supérieure - Rennes (ENS Rennes)-Université de Bretagne Sud (UBS)-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Télécom Bretagne-Université de Rennes 1 (UR1), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Institut de Recherche en Informatique et Systèmes Aléatoires (IRISA), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-École normale supérieure - Rennes (ENS Rennes)-Université de Bretagne Sud (UBS)-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), and Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)

Subjects
0106 biological sciences, Water mass, 010504 meteorology & atmospheric sciences, Coccolithophore, [SDV]Life Sciences [q-bio], Population, Aquatic Science, Oceanography, 01 natural sciences, Coccolith, Water column, Summer phytoplankton community, Coccolith calcite, Coccolithophores, Summer phytoplankton community, Western Barents Sea, Coccolithophores, Photic zone, 14. Life underwater, education, Ecology, Evolution, Behavior and Systematics, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, Emiliania huxleyi, Polar front, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, education.field_of_study, biology, Western Barents Sea, 010604 marine biology & hydrobiology, Coccolith calcite, biology.organism_classification, 13. Climate action, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Geology
Abstract

International audience; The Barents Sea is particularly vulnerable to large-scale hydro-climatic changes associated with the polar amplification of climate change. Key oceanographical variables in this region are the seasonal development of sea-ice and the location and strength of physico-chemical gradients in the surface and subsurface water layers induced by the convergence of Arctic- and Atlantic-derived water masses. Remote sensing imagery have highlighted the increasing success of calcifying haptophytes (coccolithophores) in the summer phytoplankton production of the Barents Sea over the last 20years, as a response to an overall larger contribution of Atlantic waters to surface and sub-surface waters, as well as to enhanced sea-ice melt-induced summer stratification of the photic layer.The present study provides a first thorough description of coccolithophore standing stocks and diversity over the shelf and slope of the western Barents Sea from two sets of surface and water column samples collected during August–September 2014 from northern Norway to southern Svalbard. The abundance and composition of coccolithophore cells and skeletal remains (coccoliths) are discussed in view of the physical–chemical–biological status of the surface waters and water column based on in-situ (temperature, salinity, fluorescence) and shore-based (microscope enumerations, chemotaxonomy) measurements, as well as satellite-derived data (Chl a and particulate inorganic carbon contents).The coccolithophore population is characterized by a low species diversity and the overwhelming dominance of Emiliania huxleyi. Coccolithophores are abundant both within the well stratified, Norwegian coastal water — influenced shallow mixed layer off northern Norway, as well as within well-mixed cool Atlantic water in close vicinity of the Polar Front. Bloom concentrations with standing stocks larger than 4million cells/l are recorded in the latter area north of 75°N. Our limited set of chemotaxonomic data suggests that coccolithophores contribute substantially (ca. 20% of the total Chl a) to the summer phytoplankton community which is made essentially of small-sized algal groups. Excluding the bloom area, coccolith calcite accounts for an average of 20% to the bulk particulate inorganic carbon content in the surface waters, and explains to some extent the satellite-derived spatial distribution of this parameter. Deep water living coccolithophore species thriving below the pycnocline as well as populations present in well-mixed cool Atlantic water are rapidly transferred to depth in the form of intact coccospheres down to at least 200m. High amplitude internal waves which, according to our observations, affect a wide range of water depth up to the lower photic zone, might strengthen the vertical transfer of this sinking population.

Published
2016

46. New insights into the morphology and sedimentary processes along the western slope of Great Bahama Bank

Author

François Fournier, John J. G. Reijmer, Eliane Gonthier, Mélanie Principaud, Emmanuelle Ducassou, Gregor P. Eberli, I. Billeaud, R. Joussiaume, B. Marsset, Philippe Léonide, M. Pakiades, Pascal Kindler, Thierry Mulder, C. Bondu, Vincent Hanquiez, Dynamic Earth and Resources, and Amsterdam Global Change Institute

Subjects
Canyon, geography, geography.geographical_feature_category, Turbidity current, Sorting (sediment), Geology, Structural basin, Slump, chemistry.chemical_compound, Paleontology, chemistry, Carbonate, Sedimentary rock, Siliciclastic, SDG 14 - Life Below Water, Geomorphology
Abstract

New high-quality multibeam and seismic data image the western slope of the Great Bahama Bank and the adjacent floor of the Straits of Florida. The extensive survey reveals several unexpected large- and small-scale morphologies. These include bypass areas, channel-leveelobe systems, gullied slopes, and products of slope instabilities at various scales, including long slump scars at the lower slope and mass transport complexes that extend ~30 km into the adjacent basin floor. The toe of the slope is irregularly covered with deep-water carbonate mounds. The abundance of the individual morphological features varies from north to south. From 26°00'N to 25°20'N, the slope is dissected by numerous deep canyons that abruptly end southward, where the slope is characterized by a smooth lower portion and small regularly spaced furrows in its upper part. Further south, two long (25-50 km) scars document instability at the lower slope. One of these scars is the source area of a large mass transport complex. In addition to this large-scale feature, several types of gravity-induced sedimentary processes are revealed. Most of the morphologies and inferred processes of this carbonate system are similar to those observed in siliciclastic systems, including mass transport complexes, gravity currents initiated by density cascading, and overspilling channeled turbidity currents. For the first time, a clear asymmetric channel-levee system has been identified along the slope, suggesting similitude in sorting processes between carbonate and siliciclastic systems and enhancing the reservoir-bearing potential of carbonate slopes. Notable differences with siliciclastic systems include: the lack of connection with the shallow and emerged part of the system (i.e., bank top), and the small size of the sedimentary system. © 2012 Geological Society of America.

Published
2012

47. Submarine slide initiation and evolution offshore Pointe Odden, Gabon — Analysis from annual bathymetric data (2004–2009)

Author

Vincent Hanquiez, E. Braccini, D. Leynaud, J.-P. Crespin, Thierry Mulder, J.-M. Gallissaires, Laurie Biscara, Vincent Marieu, and Thierry Garlan

Subjects
Waves and shallow water, Longshore drift, Geochemistry and Petrology, Erosion, Submarine, Sediment, Geology, Bathymetry, Submarine pipeline, Oceanography, Geomorphology, Seafloor spreading
Abstract

Time serial bathymetric data acquired between 2004 and 2009 are used to evaluate the morphological evolution of the coastal area offshore Pointe Odden, located on the Mandji Island (Gabon). Data analysis highlights the alternation between fast sedimentation periods at shallow water depth related to intense longshore drift and catastrophic erosional events. Because of sediment overloading and slope oversteepening, small-scale instabilities are generated (successive slide scars, channel formation and growth by retrogressive erosion). However, when critical stability conditions are reached, large failures occur (2005 submarine slide). Geotechnical measurements and sedimentological analyses on the study area suggest that flow liquefaction would be the triggering mechanism of the 2005 event. Moreover, our analysis shows that the associated slide scar is rapidly filled by compensation and that failure morphology could disappear from the seafloor in about 15–20 years.

Published
2012

48. Perched lobe formation in the Gulf of Cadiz: Interactions between gravity processes and contour currents (Algarve Margin, Southern Portugal)

Author

Michel Cremer, Thierry Garlan, Elodie Marchès, Eliane Gonthier, Pascal Lecroart, Vincent Hanquiez, and Thierry Mulder

Subjects
Canyon, geography, geography.geographical_feature_category, Continental shelf, Stratigraphy, Sediment, Geology, Contourite, Terrace (geology), Erosion, Sedimentary rock, Quaternary, Geomorphology
Abstract

The Gulf of Cadiz is swept by the strong saline Mediterranean Outflow Water (MOW). On the Algarve Margin (South Portugal), this current has constructed fine-grained contourite drifts. This margin is dissected by the Portimao Canyon and three short channels that only incise the upper slope, and are absent on a terrace located at mid-slope depths along the Algarve Margin. High-resolution seismic profiles and sediment cores highlight the original architecture of the sedimentary deposits on this terrace. Coarse-grained lenticular chaotic bodies formed during major relative sea-level lowstands are intercalated within the drift. The lobate shape and sandy nature of the lenticular chaotic bodies and their location at the mouths of the three short channels suggest they are gravity-generated deposits that are perched on the middle continental slope. In the Gulf of Cadiz, the interaction between contour current and gravity processes is strongly controlled by climatic variations and relative sea-level changes during the late Quaternary. During cold periods when sea-level was low, erosion intensified on the continental shelf and the deepest part of MOW was active. Sediment was transported downslope through the channels and deposited on sedimentary lobes perched on the mid-slope terrace. During warm periods when relative sea-level was high, the supply of sediment from the shelf was shut off and the shallowest part of MOW was more active. Contourite drifts fill the channels and bury the sandy lobes.

Published
2010

49. The sandy channel–lobe depositional systems in the Gulf of Cadiz: Gravity processes forced by contour current processes

Author

Pascal Lecroart, Eliane Gonthier, Vincent Hanquiez, Samuel Toucanne, Elodie Marchès, Thierry Mulder, Cédric Bonnel, Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Environnements Sédimentaires - Géosciences Marines (GM/LES), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Centre Jacques-Petit - Archives, Textes et Science des Textes (ATST), Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Laboratoire des Fluides Complexes et leurs Réservoirs (LFCR), and Centre National de la Recherche Scientifique (CNRS)-Université de Pau et des Pays de l'Adour (UPPA)-TOTAL FINA ELF

Subjects
010504 meteorology & atmospheric sciences, Stratigraphy, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, 010502 geochemistry & geophysics, deposition, 01 natural sciences, Quaternary, Sedimentary depositional environment, Mediterranean Outflow Water, Gulf of Cadiz, climate oscillation, gravity field, Sedimentology Engineering main heading: Process control GEOBASE Subject Index: climate change, continental slope, 14. Life underwater, Sedimentology, Geomorphology, 0105 earth and related environmental sciences, geography, geography.geographical_feature_category, Sandy lobes Engineering controlled terms: Anoxic sediments, Continental shelf, Sediment, marine sediment, sedimentation Regional Index: Atlantic Ocean, Geology, Contourite, climate forcing, sediment core, 13. Climate action, Contourite channels, contourite, Progradation, Retrogradation
Abstract

International audience; The sedimentation in the Gulf of Cadiz (NE Atlantic Ocean) is significantly controlled by the Mediterranean Outflow Water (MOW). Along its pathway onto the continental slope, the MOW is canalized by contourite channels, some of them feeding gravity sandy channel-lobe depositional systems firstly recognized in previous study [Habgood et al., 2003. Deep-water sediment wave fields, bottom current sand channels and gravity flow channel-lobe systems: Gulf of Cadiz, NE Atlantic. Sedimentology 50(3), 483-510.].Using very high resolution acoustic data and cores, a detailed characterization and a new evolution pattern of these channel-lobe depositional systems is established. Complex internal geometry of the lobes shows several depositional units revealing a polyphase evolution of these systems, with a general progradation punctuated by retrogradation and avulsion phases. A gravity origin controlled by contouritic processes and climatic changes is demonstrated for the feeding and the evolution of these sandy channel-lobe depositional systems. Climate oscillations, via the MOW variations, act as a major forcing of the activity of the channel-lobe depositional systems during the Late Quaternary.

Published
2010

50. High-resolution analysis of submarine lobes deposits: Seismic-scale outcrops of the Lauzanier area (SE Alps, France)

Author

Thierry Mulder, Elodie Marchès, Sébastien Zaragosi, Yannick Callec, Brice Ferger, Jean-Luc Schneider, Olivier Parize, Mathieu Gaudin, Samuel Toucanne, Tristan Salles, Cécile Robin, Cédric Bonnel, Emmanuelle Ducassou, Philippe Joseph, Fabien Linares, Jonathan Allard, Emmanuel Dujoncquoy, Vincent Hanquiez, Samuel Etienne, Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Département Géosciences (AREVA-BU Mines), Groupe AREVA, IFP Energies nouvelles (IFPEN), Géosciences Rennes (GR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre Armoricain de Recherches en Environnement-Centre National de la Recherche Scientifique (CNRS), Université de Pau et des Pays de l'Adour (UPPA), Unité de recherche Géosciences Marines (Ifremer) (GM), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre Armoricain de Recherches en Environnement-Centre National de la Recherche Scientifique (CNRS), and Géosciences Marines (GM)

Subjects
Turbidity current, Gravity processes, 010504 meteorology & atmospheric sciences, Outcrop, Stratigraphy, Channelled lobe, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Geology, Annot Sandstone, 010502 geochemistry & geophysics, Topographic compensation, 01 natural sciences, Unconformity, Sedimentary depositional environment, Paleontology, Non-channelled lobe, Clastic rock, Confined basin, Facies, Sedimentary rock, Progradation, Geomorphology, 0105 earth and related environmental sciences
Abstract

International audience; The Lauzanier area represents the northernmost extension of the Annot Sandstone series and contains deposits between 650 and 900 m-thick. This basin was active from upper Bartonian or lower Priabonian to early Rupelian. It is composed of two superposed units separated by a major unconformity. The sediment supply is due to channelled flows coming from the south. Flow processes include mass flow to turbidity currents. The size of the particles and the absence of fine-grained sediment suggest a transport over a short distance. The Lower Unit is made of coarse-grained tabular beds interpreted as non-channelled lobe deposits. The Upper Unit is made of massive conglomerates interpreted as the channelled part of lobes. These lobe deposits settle in a tectonically confined basin according to topographic compensation that occurs from bed scale to unit scale. The abrupt progradation between the lower and the upper unit seems related to a major tectonic uplift in the area. This uplift is also suggested by a change in the petrographic nature of the source and an abrupt coarsening of the transported clasts. This field example allows providing high resolution analysis for depositional sedimentary sequences of terminal lobe deposits in a coarse-grained turbidite system. The outcrop analysis shows the lateral evolution of deposits and the system progradation allows a longitudinal analysis of facies evolution by superposing on the same outcrops the channelled lobe system and the non-channelled lobe system. These results of high-resolution outcrop analysis can be extrapolated to results obtained on sedimentary lobes in recent deep-sea turbidite system that are either restricted to cores, or with a lesser resolution (seismic).

Published
2010

Catalog

Books, media, physical & digital resources
See catalog results