Éditeur(s) : Springer
Résumé : The Balearic Basin is a young basin composed of thick Plio-Quaternary sediments, including active gravity sedimentation. During the Quaternary, gravity processes deposited (1) turbidite systems, either as symmetrical fans (Petit-Rhone and Valencia fans) or asymmetrical ridges (Marseille-Planier, Grand- Rhone and Pyreneo-Languedocian ridges) and (2) several mass-transport deposits, indicating recurrent sedimentary failures of the margin. This paper synthesizes previous works and proposes a chronological sedimentary evolution for the basin. Except for the last 20 ka, the chronostratigraphy remains poorly constrained but should soon be established for the last 500 ka, based on the PROMESS1 drillings on the outer shelf of the Gulf of Lions, and hopefully for the last 30 Ma, based on ultra-deep drilling in the deep basin from aboard the Chikyu research vessel (IODP proposal Pre699).
Geo-Marine Letters (0276-0460) (Springer), 2006-12 , Vol. 26 , N. 6 , P. 347-359

Droits : 2006 Springer Science+Business Media
http://archimer.ifremer.fr/doc/2006/publication-2171.pdf
DOI:10.1007/s00367-006-0044-0
http://archimer.ifremer.fr/doc/00000/2171/

Éditeur(s) : Elsevier
Résumé : Emplacement of post-glacial turbidites is commonly controlled by rapid changes in sea level or by seismicity. On the continental rise of the Gulf of Lions (Western Mediterranean), an aseismic area, we identified turbiditic beds deposited during the rising stage and highstand of sea level. Swath bathymetry, sediment cores, in situ Cone Penetrating Tests (CPTU), heavy mineral associations and radiocarbon dating determined the source, composition, distribution and age of the turbiditic beds. Turbidites are composed of homogeneous to positively graded silts to medium sand with quartz (up to 90%), shell debris and shelfal benthic faunas. Their distribution on the sea floor is very patchy and controlled by abundant inherited erosional bedforms. Their source is found in relict regressive sands at the outershelf. Their deposition occurred just after the onset of the post-glacial sea level rise and the concomitant sediment starvation of the Rhone deep sea turbiditic system until recently. Whilst canyons are fed with sand by strong seasonal hydro-sedimentary dynamics on the outershelf, the emplacement of post-glacial turbidites is not controlled by sea level changes but probably by the periodic flushing of the canyons. Our study revealed that this low energy aseismic margin undergoes significant transport of sand, down to the base of slope, during the sea-level rise and the Holocene highstand.
Marine Geology (0025-3227) (Elsevier), 2009-02 , Vol. 257 , N. 1-4 , P. 65-86

Droits : 2009 Published by Elsevier Ltd.
http://archimer.ifremer.fr/doc/2009/publication-6316.pdf
DOI:10.1016/j.margeo.2008.10.013
http://archimer.ifremer.fr/doc/00000/6316/

Éditeur(s) : HAL CCSD Société géologique de France
Résumé : The Maguelone shore extends along the northern coast of the Gulf of Lions margin, West of the Rhone delta and East of some high gradient coastal streams that have been providing most of the elastic sediments to the Gulf of Lions margin since the early Miocene. This 10 km wide area comprises an onshore small coastal watershed (15 km long) in low-lying carbonate hills, kilometer wide marshes, sandy beach and shoreface featuring local low sedimentation. Deposit architecture in such a coastal zone records dynamics of incised valley fill under the influence of rivers and wave/current hydrodynamics in a microtidal environment during an eustatic cycle.;A detailed analysis of about 250 km of very high resolution seismic profiles, tens of cores and outcrops data revealed the evolution of the Maguelone coastal system from Late-Quaternary to present-day. It highlighted also dominant denudation processes in the upstream catchments associated to the formation of incised valley seaward during Quaternary. Combination of this inherited morphology together with hydrodynamics controlled the lagoonal environment evolution since the last transgression. In particular, the Maguelone shore is characterized by the formation of built-over-rias lagoonal systems and records an evolution from partially protected lagoon to isolated lagoon environment. These two stages of lagoon evolution correspond to distinct deposit environments. Correlation of fauna contents with deposit geometry improves lagoonal environment models.
EISSN: 1777-5817

hal-00486370
https://hal.archives-ouvertes.fr/hal-00486370
DOI : 10.2113/gssgfbull.181.2.211

Éditeur(s) : Amer Soc Limnology Oceanography
Résumé : A new benthic station equipped with oxygen microelectrodes and environmental sensors was developed by Laboratoire des Sciences du Climat et de L’Environnement (LSCE) and Division Technique of the Institut National des Sciences de L’Univers (DT-INSU) to perform in situ time series monitoring of sediment oxygen demand, linked to the mineralization of organic matter. The time series typically cover periods of 2-3 months, with a base frequency of 1 set of oxygen profiles per day. The profiling head assessed the lateral heterogeneity of the sediment oxygen demand at the beginning of the time series over a 0.8-m long rectangle to discriminate spatial and temporal variability. A continuous recalibration is performed using a moored oxygen optode anchored to the benthic station together with a set of environmental sensors. These sensors (turbidity, temperature, salinity, and oxygen) can trigger a high-frequency profiling mode to investigate the fate of particulate organic matter delivered during floods, resuspension, and deposition events. Deployments of the benthic station were performed in the Rhone River subaqueous delta (Mediterranean Sea). We show that “stable” periods (when neither floods nor storms occur) were characterized by a stable oxygen demand. In the case of resuspension events, an increase of the sediment oxygen demand by a factor of 2-3 with a relaxation time of 1 day was observed, indicating that the new benthic station can adequately capture the impact of resuspension events on the oxygen demand in deltaic sediments.
Limnology And Oceanography-methods (1541-5856) (Amer Soc Limnology Oceanography), 2014-11 , Vol. 12 , P. 729-741

Droits : 2014, by the American Society of Limnology and Oceanography, Inc.
http://archimer.ifremer.fr/doc/00230/34126/32597.pdf
http://archimer.ifremer.fr/doc/00230/34126/36349.pdf
DOI:10.4319/lom.2014.12.729
http://archimer.ifremer.fr/doc/00230/34126/

Éditeur(s) : Elsevier
Résumé : The fining upward trend commonly described on levees of turbidite systems can be either attributed to changes in the sediment supply (external forcing = allocyclic) or changes in the spillover processes related to the growth of the levee (internal forcing = autocyclic). However the real causes remain speculative and difficult to demonstrate. Knowledge of vertical change in flow velocity (or grain size) in turbidity currents, of the turbidity current's height, as well as the growth rate of a levee are theoretically sufficient to describe the evolution of the grain size of a leveed turbidite sequence deposited by spillover processes. A piston core (MD99-2344) retrieved on the right levee of the Petit-Rhone neofan, sampled an 8.50 m long turbidite sequence containing more than one hundred turbidite beds and showing a marked fining upward trend. With the help of two profiles describing respectively the vertical velocity [Stacey, M. and Bowen, A.J., 1988b. The vertical structure of turbidity currents and a necessary condition for self-maintenance, Journal of Geophysical Research, pp. 3543-3553.] and the vertical grain size [Migeon, S., 2000. Dunes geantes et levees sedimentaires en domaine marin profond: approche morphologique, sismique et sedimentologique. PhD Thesis, Universite Bordeaux 1, Talence, France, 288 pp.] of a turbidity current, and a simple graphical method, we test several hypotheses on the height of the turbidity current and on the grain size at the bottom of the turbidity current and we attempt to reproduce the vertical fining upward trend. Our results show that the fining upward trend of the turbidite facies can be explained by the aggradation of the turbidite levee and the gradual confinement of the turbidity currents in the channel. This is, therefore, an autocyclical phenomenon. However a high frequency variability of the grain size overprinted on the trend cannot be explained by internal forcing and is believed to be allocyclical, depending on changes to the sediment input. The vertical grain-size profile allows more realistic flow conditions to be determined and shows that the vertical velocity profile does not describe the ability of turbidity current to transport sediment. This simple graphical method allows a better understanding and quantification of the forcing on turbidite deposits and improves description of the characteristics of the turbidity currents from the grain size of the deposits.
Marine Geology (0025-3227) (Elsevier), 2006-12 , Vol. 234 , N. 1-4 , P. 191-213

Droits : 2006 Elsevier
http://archimer.ifremer.fr/doc/2006/publication-2311.pdf
DOI:10.1016/j.margeo.2006.09.019
http://archimer.ifremer.fr/doc/00000/2311/

Éditeur(s) : Elsevier
Résumé : The composition of the glacial vegetation of southern French plains has been a matter of debate for several decades. Vegetation is considered as steppic according to French and Spanish lacustrine pollen records whereas cave deposits suggest the presence of mesothermophilous trees through the Last Glacial Maximum. In our paper, we display new palynological records from marine sediments of the Gulf of Lions. They indicate the presence of Abies, Picea and deciduous Quercus in the Gulf of Lions, certainly located in the drainage basins of the Pyreneo-Languedocian rivers. These populations that were sensitive to short climatic events during Marine Isotopic Stage 2 could have been linked to northeastern Spanish and southeastern French relicts already evidenced by phylogenetic data. These trees were absent from the Rhone drainage basin during the deglaciation and certainly also disappeared from the Pyreneo-Languedocian drainage basins from ca 17 to 15 ky cal BP. Finally, the Last Glacial Maximum does not appear as stable, cold and dry as previously thought.
Quaternary Science Reviews (0277-3791) (Elsevier), 2007-04 , Vol. 26 , N. 7-8 , P. 1037-1054

Droits : 2007 Elsevier Ltd All rights reserved.
http://archimer.ifremer.fr/doc/2007/publication-2804.pdf
DOI:10.1016/j.quascirev.2006.12.009
http://archimer.ifremer.fr/doc/00000/2804/

Résumé : L'année 2004, année du vingtième anniversaire de sa création, aura été marquée, pour l'Ifremer, par une intense activité. 2004 a en effet été d'abord une année d'investissements et de résultats: de la biodiversité des massifs de coraux froids à la capacité des bactéries à produire des polymères biodégradables, de l'observation des effets de la crue centennale du Rhône sur les sédiments à la variabilité de l'hydrologie dans l'Atlantique Nord, de l'effet de la pluviométrie en hiver sur la mortalité estivale des huîtres à la sensibilisation environnementale des crevettes aux bactéries pathogènes, au lever par Lidar aéroporté de plus de 900 km² d'estrans de Bretagne, les résultats scientifiques ont été nombreux La technologie n'a pas été en reste avec les progrès de la protection contre la corrosion marine, les essais concluants de l'AUV, la mise à l'eau du Pourquoi pas?, ni les activités de surveillance du fait de l'augmentation des apparitions de toxines dans les coquillages. L'institut a en outre mené en 2004, avec ses ministères de tutelle, un important effort de réflexion sur ses missions et ses priorités, dont le contrat quadriennal 2005-2008, approuvéen conseil à' administration, finalisé en fin d'année et signé le 25 mai 2005 en présence de quatre ministres, trace désormais le cadre, en cohérence avec notre plan stratégique. [OCR NON CONTRÔLE]

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2004/rapport-4830.PDF
http://archimer.ifremer.fr/doc/00000/4830/