Éditeur(s) : Université de Paris 7
Résumé : The Seine estuary and its adjacent region Pays de Caux are two significant sources of mercury for coastal marine environments. It is carried through fluvial means for the Seine bay and through karstic fresh water emergences for Pays de Caux's coastal area. Mercury cycle in the Seine estuary and bay is affected by additional anthropical activities. The estuary's maximal turbidity area acts like a trap and a chemical reactor for fluvial mercury. Within this area, we can confirm: (i) the non conservative behaviour of dissolved mercury; (ii) mercury enrichment of particles when comparing the Seine's and marine environment and we suggest mercury particle redistribution from the organic fraction to the oxyhydroxydes fraction. A large fraction of mercury is exported in this state towards coastal areas. Mercury reduction in surface coastal waters and its atmospherical recycling are major phenomena. Photoreduction and biological reduction play quantitative roles equivalent to total mercury recycling via the atmosphere corresponding approximately to 30 % of fluvial exchanges. We are demonstrating that reactive forms of mercury are supporting photoreduction. Mercury behaviour within Pays de Caux's karst depends of the hydrogeological context of the system (time and flow speed, turbidity, flow); regardless of the speciation and/or partition in underground waters, the total amount of mercury in intertidal areas is quantitatively the same as in the Seine estuary. Mercury brought through intertidal emergences (karstic exudations) is not « filtered » by a maximal turbidity area and is more widely bio-available for mussels than in the Seine estuary. Even being free from growth factor influences through simple models, mussels found in Pays de Caux still show one of the highest mercury contamination on the French coast; for the first time this places the emphasis on how much mercury is brought from underground waters to the coastal environment. Surface complexation modelisation tests are able to reproduce the major part of mercury partition in the Seine estuary and bay if a very low mercury exchangeable fraction and minimum complexation parameters are taken into account; thermodynamic calculations also suggest that a strong or highly concentrated « dissolved » ligand must be present in the water in order to compete with chlorocomplex formations and explain our measures.
L'estuaire de la Seine et la région adjacente du Pays de Caux sont deux sources significatives en mercure pour le milieu marin côtier. Les apports sont d'une part fluviatiles en ce qui concerne la Baie de Seine et karstiques via des émergences d'eau douce pour la zone côtière du Pays de Caux. Le cycle du mercure en estuaire et baie de Seine est perturbé par les apports liés aux activités anthropiques. La zone de turbidité maximum de l'estuaire joue le rôle de piège et de réacteur chimique pour le mercure fluviatile. Au sein de cette zone, nous mettons en évidence : (i) un comportement non-conservatif du mercure dissous; (ii) un enrichissement en mercure des particules par rapport à celles de la Seine et du milieu marin et suggérons une redistribution du mercure particulaire de la fraction organique vers la fraction oxyhydroxydes. C'est sous cette forme qu'une fraction importante du mercure est exportée vers la zone côtière. La réduction du mercure dans les eaux côtières de surface et son recyclage atmosphérique sont des phénomènes majeurs. En effet, la photoréduction et la réduction biologique jouent des rôles quantitativement équivalents avec un recyclage total du mercure via l'atmosphère correspondant à environ 30% des apports fluviatiles. Nous montrons que les formes réactives du mercure constituent le substrat de la photoréduction. Le comportement du mercure au sein du karst du Pays de Caux dépend du contexte hydrogéologiques du système (temps et vitesse de circulation, turbidité, débit) ; quelle que soit la spéciation et/ou la partition dans les eaux souterraines, l'apport en mercure total à la zone intertidale est quantitativement du même ordre de grandeur que les apports de la Seine. Le mercure apporté par les émergences intertidales (exutoires karstiques) n'est pas « filtré » par une zone de turbidité maximale et se trouve plus largement biodisponible pour les moules qu'en estuaire de Seine. En s'affranchissant, par des modèles simples, de l'influences des facteurs de croissance, les moules du Pays de Caux affichent toujours une contamination par le mercure parmi les plus élevées du littoral français; ceci met pour la première fois l'emphase sur l'importance de l'apport en mercure par des eaux souterraines dans un environnement côtier. Les essais de modélisation de complexation de surface reproduisent la majeure partie de la partition du mercure dans l'estuaire et la baie de Seine si l'on tient compte d'une fraction échangeable en mercure très faible et de paramètres de complexation minimums ; les calculs thermodynamiques suggèrent aussi qu'un ligand « dissous » fort ou présent à de fortes concentrations doit être présent dans l'eau afin d'entrer en compétition avec la formation de chlorocomplexes et expliquer nos mesures.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2001/these-1842.pdf
http://archimer.ifremer.fr/doc/00000/1842/

Éditeur(s) : Université de Brest
Résumé : The channel-lobe transition zone has been studied in two turbiditic systems: the Amazon channel-mouth lobe complex at the termination of the last eight channel-levee systems and the Neochannel termination, the last active channel of the Petit-Rhone turbidite system. - In the two cases, the internal geometry and stacking pattern of the deposits show a significant control of the configuration (size and shape) of the receiving basins, their morphology (gradients and subtle gradient changes), and their degree of confinement. - The Amazon and Petit-Rhone systems, with lobes built after the Last Glacial Maximum and the ensuing sea-level rise, evidence the major impact of external forcings (climatic events and eustatic variations) that induce variations in sediment fluxes delivered to the deep basin and therefore exert a control on channel-mouth lobes construction. The channel-mouth lobes of the Amazon and Petit-Rhone systems, even if they are located at great distances from the river mouths, at the termination of the turbidite systems and in areas characterised by subtle morphological variations, are both constrained by combined internal (accommodation and compensation) and external factors (post-glacial deconnection between the fluvial system and the deep basin).
La zone de transition chenal-levées/lobes a été étudiée dans 2 systèmes turbiditiques : le complexe de lobes à la terminaison des 8 derniers chenaux de l'éventail de l'Amazone et la terminaison du Néochenal, dernier chenal de l'éventail du Petit-Rhône. - Dans les deux cas, l'agencement des dépôts et leur évolution dans l'espace et le temps révèlent un fort contrôle de la configuration des réceptacles (taille et forme), de la morphologie des fonds (pentes et taux de changement des pentes) et du degré de confinement. - Les systèmes de l'Amazone et du Petit-Rhône, dont les lobes se sont construits à partir du Dernier Maximum Glaciaire et lors de la remontée du niveau marin qui a suivi, ont en outre permis de souligner l'impact majeur, sur la mise en place des lobes terminaux, de certains forçages externes (événements climatiques et variations eustatiques), qui déterminent les variations des flux sédimentaires arrivant au bassin. Ainsi, bien que situés à des distances considérables des sources fluviatiles et dans des zones distales où les variations de relief sont très ténues, les lobes terminaux de ces deux grands systèmes turbiditiques se sont révélés contraints à la fois par des processus internes (processus de compensation) et par des processus externes (déconnexion post-glaciaire du fleuve et du bassin).

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2008/these-6796.pdf
http://archimer.ifremer.fr/doc/00000/6796/

Éditeur(s) : Gauthier-Villars
Résumé : The distribution and behaviour of nutrients (nitrate, nitrite, ammonia, silicate and phosphate) have been examined over the course of a year in two major Scottish estuaries, the Forth and Tay. Maximum concentrations of nitrate and silicate in both estuaries occur in winter, when mixing is conservative. By contrast maximum phosphate, ammonia and nitrite concentrations (notably in the Forth) are observed in summer, these are related to lower oxygen concentrations both within the water column and sediments. Phosphate, ammonia and nitrite concentrations are high in the Forth relative to the Tay. Phosphate behaviour in plots for both estuaries show some common features including removal at low salinity, mid estuary inputs and simple dilution at high salinity. The results are interpreted on the basis of removal onto particles at low salinity followed by desorption at higher salinity together with an input from sediment porewaters. In the Forth the phosphate flux from sediments during the summer is estimated to be 1.98 +/- 1.25 mmol m-2 day-1. At this time the river input of phosphorus is only 10- 14 % of the mid estuary input. Under low river flow conditions in summer a large turbidity maximum (400-500 mg l-1 suspended solids) develops in the Forth estuary and this results in removal of phosphate. Removal is less dramatic in the Tay estuary as the turbidity is wind generated and therefore rarely exceeds 100 mg 1-1. Water quality in the Forth (as defined by the occurrence of low dissolved oxygen concentrations and the presence of species such as ammonia and nitrite) is inferior to that of the Tay. Relative to contaminated estuaries however concentrations in both estuaries are low. By virtue of its high fresh water discharge the Tay is a more significant source of nitrate to the North Sea during the winter than is the Forth. In the Forth bacterial mineralisation and nitrification of organic nitrogen occurs in the upper estuary, this results in an input of nitrate and consumption of dissolved oxygen. Further downstream broad mid estuarine peaks of nitrite and ammonia are observed indicative of a benthic source. Estimates of this source for ammonia and nitrite are 19-44 and 3.9-8.1 mmol m-2 day-1 respectively. In winter the main source of nitrogen to the Forth is from the river but in summer mid estuarine sources dominate. In the outer Tay a peak in dissolved ammonia is estimated to represent an input of 0.5-1.1 tonnes N day-1, this is attributed to sewer inputs from Dundee.
Oceanologica Acta (0399-1784) (Gauthier-Villars), 1992 , Vol. 15 , N. 3 , P. 261-277

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00100/21160/18779.pdf
http://archimer.ifremer.fr/doc/00100/21160/

Éditeur(s) : Estuaries Research Federation
Résumé : Estuarine systems are complex environments where seasonal and spatial variations occur in concentrations of suspended particulate matter, in primary constituents, and in organic matter content. This study investigated in the laboratory the flocculation potential of estuarine-suspended particulate matter throughout the year in order to better identify the controlling factors and their hierarchy. Kinetic experiments were performed in the lab with a "video in lab" device, based on a jar test technique, using suspended sediments sampled every 2 months over a 14-month period at three stations in the Seine estuary (France). These sampling stations are representative of (1) the upper estuary, dominated by freshwater, and (2) the middle estuary, characterized by a strong salinity gradient and the presence of an estuarine turbidity maximum. Experiments were performed at a constant low turbulent shear stress characteristic of slack water periods (i.e., a Kolmogorov microscale > 1,000 A mu m). Flocculation processes were estimated using three parameters: flocculation efficiency, flocculation speed, and flocculation time. Results showed that the flocculation that occurred at the three stations was mainly influenced by the concentration of the suspended particulate matter: maximum floc size was observed for concentrations above 0.1 g l(-1) while no flocculation was observed for concentrations below 0.004 g l(-1). Diatom blooms strongly enhanced flocculation speed and, to a lesser extent, flocculation efficiency. During this period, the maximum flocculation speed of 6 A mu m min(-1) corresponded to a flocculation time of less than 20 min. Salinity did not appear to automatically enhance flocculation, which depended on the constituents of suspended sediments and on the content and concentration of organic matter. Examination of the variability of 2D fractal dimension during flocculation experiments revealed restructuring of flocs during aggregation. This was observed as a rapid decrease in the floc fractal dimension from 2 to 1.4 during the first minutes of the flocculation stage, followed by a slight increase up to 1.8. Deflocculation experiments enabled determination of the influence of turbulent structures on flocculation processes and confirmed that turbulent intensity is one of the main determining factors of maximum floc size.
Estuaries and coasts : Journal of the Estuarine Research Federation (1559-2723) (Estuaries Research Federation), 2009-07 , Vol. 32 , N. 4 , P. 678-693

Droits : 2009 Springer
http://archimer.ifremer.fr/doc/2009/publication-6631.pdf
DOI:10.1007/s12237-009-9160-1
http://archimer.ifremer.fr/doc/00000/6631/

Éditeur(s) : Pergamon-elsevier Science Ltd
Résumé : Sites of monomethylmercury (MMHg) production in Amazonian regions have been identified in hydraulic reservoirs, lake sediments and wetlands, but tailings ponds have not yet received sufficient attention for this purpose. This work evidenced high MMHg production within the water column and the interstitial water of two tailings ponds of French Guiana Au mines located; (i) in a small scale exploitation (Combat) where Hg was used for Au amalgamation, and (ii) in an industrial on-going Au mine (Yaoni) processing without Hg. The (MMHg)(D) maximum (2.5 ng L-1) occurred in the oxic water column above the sediment-water interface (SWI) of the most recent tailings pond (Combat), where the substrate was fresh, the redox transition was sharp and the pool of total Hg was large. In the Yaoni pond, the (MMHg)(D) maximum concentration (1.4 ng L-1) was located at the SWI where suboxic conditions prevailed. Using the (MMHg)(D) concentration as a proxy for Hg methylation rates, the present results show that Hg methylation may occur in various redox conditions in tailings ponds, and are favored in areas where the organic matter regeneration is more active. A 3-month long laboratory experiment was performed in oxic and anoxic boxes filled with high turbidity waters from the Combat Au mine to simulate tailings ponds. Slaked lime was added in an experimental set (2 mg L-1)and appeared to be very efficient for the reduction of suspended particulate matter (SPM) to environmentally acceptable concentrations. However, at the end of the experiment, large (MMHg)(D) concentrations were monitored under treated anoxic conditions with the (MMHg)(D) maximum located at the SWI above the Fe-reducing zones. No (MMHg)(D) was detected in oxic experiments. The use of slaked lime for SPM decantation appears to be an efficient and non-onerous process for Au miners to avoid Hg methylation in tailings ponds when it is combined with rapid drainage of the mine waters. A subsequent human intervention is however necessary for the recovery of soil structure through the cover of dried ponds with organic rich materials and reforestation to avoid the stagnation of rain waters and the occurrence of anoxia. (C) 2010 Elsevier Ltd. All rights reserved.
Applied Geochemistry (0883-2927) (Pergamon-elsevier Science Ltd), 2011-02 , Vol. 26 , N. 2 , P. 222-229

Droits : 2010 Elsevier Ltd All rights reserved.
http://archimer.ifremer.fr/doc/00030/14117/12133.pdf
DOI:10.1016/j.apgeochem.2010.11.022
http://archimer.ifremer.fr/doc/00030/14117/

Éditeur(s) : Université de Bretagne Occidentale
Résumé : Study of mineral suspended particulate matter (SPM) is essential to understand ecosystem dynamics. SPM influences light penetration which is closely related to primary production and carries pollutants and nutrients within the water masses. This work aims to study near-surface mineral SPM dynamics in the English Channel using two complementary methods: remote-sensing by satellites and numerical modelling. Firstly, MODIS and MERIS satellite images processed by the IFREMER semi-analytical algorithm and describing non-algal SPM, are analysed to build three statistical models which are able to estimate near-surface SPM using simple variables, e.g., tidal coefficient, significant wave height and mean chlorophyll-a concentration. Secondly, the three-dimensional hydrosedimentary model ROMS (Regional Ocean Modeling System) is applied in the English Channel. It considers tidal forcing along open boundaries, wind stress at the sea-surface, wave-current interactions in the bottom boundary layer and realistic heterogeneous bottom sediments. Results of the more sophisticated statistical model is also used to impose SPM concentrations at open boundaries. Sensitivity tests on SPM boundary conditions show the importance of prescribing realistic sediment concentrations to improve the model predictions. Biological influences on mineral SPM are also tested using settling velocity and critical shear stress for erosion which vary with seasons. Both statistical and numerical models highlight and locate respective influences of tide, waves and biology on mineral SPM. Numerical predictions indicate that near-surface SPM is mainly composed of silts (>70%). Near-surface suspended silts come largely from seabed resuspension alongshore in the Eastern Channel and from the open boundaries of our limited-area coastal model at the West of Cotentin Peninsula and offshore. Near-surface SPM variations are investigated at semi-diurnal, neap-spring tidal cycle time scales and during a wave event. Finally, dynamics of sediments in the turbidity maximum zone around the Isle of Wight is examined depending on hydrodynamical conditions in order to distinguish the role played by advection and local erosion/settling processes in this area. Keywords: Suspended particulate matter, satellite, remote-sensing, modelling, English Channel, sediments, turbidity, tide, wave
L'étude des matières en suspension (MES) minérales est essentielle pour comprendre le fonctionnement des écosystèmes en Manche : les MES influencent la pénétration de la lumière dans la colonne d'eau, paramètre clé pour la production biologique, et sont susceptibles de transporter des polluants et nutriments. Lors de ce travail, la dynamique des MES minérales de surface en Manche est étudiée à l'aide de deux méthodes complémentaires : l'observation par satellite et la modélisation numérique tridimensionnelle. Dans un premier temps, les images satellite MODIS et MERIS, traitées par l'algorithme semi-analytique développé par l'IFREMER et représentant les MES non-algales de surface, sont analysées afin d'élaborer trois modèles statistiques permettant d'estimer la MES de surface en fonction de variables basiques telles que le coefficient de marée, la hauteur significative des vagues et la concentration moyenne en chlorophylle-a. Dans un deuxième temps, le modèle hydrosédimentaire multiclasse tridimensionnel ROMS (Regional Ocean Modeling System) est implémenté en Manche. Il prend en considération le forçage par la marée aux frontières ouvertes, la contrainte exercée par le vent à la surface de la mer, l'interaction houle-courant en couche limite de fond et l’hétérogénéité spatiale réaliste du lit sédimentaire. Les résultats du modèle statistique le plus sophistiqué sont également utilisés pour forcer la concentration en MES aux frontières ouvertes du domaine de calcul. Des tests de sensibilité sur les conditions limites montrent l'importance de considérer de manière réaliste les sédiments entrant en Manche par les frontières ouvertes lors de la modélisation numérique. L'influence de la biologie sur les MES minérales est testée en utilisant une formulation de la vitesse de chute et de la contrainte critique d'érosion variant saisonnièrement. Grâce à ces deux outils associés, les influences respectives de la marée, de la houle et de la biologie sur les MES minérales sont mises en avant et localisées en Manche. Le modèle numérique prédit que les MES de surface sont composées principalement de silts (>70%). Les silts en suspension en surface proviennent majoritairement du lit sédimentaire près des côtes en Manche orientale et des frontières ouvertes du domaine de calcul à l'ouest de la presqu'île du Cotentin et au large en Manche centrale et orientale. Les variations des MES de surface sont ensuite étudiées aux échelles des cycles de marée semi-diurnes, vive-eau/morte-eau et autour d'un épisode de houles. Enfin, l'évolution de la concentration de sédiments dans la zone de forte turbidité autour de l'île de Wight peut être analysée suivant les conditions hydrodynamiques afin d'évaluer les rôles respectifs des processus locaux d'érosion/dépot et d'advection dans la génération de ces turbidités remarquables. Mots-clés : Matière en suspension, télédétection, satellite, modélisation, Manche, sédiments, turbidité, marée, houle

Droits : 2013 UBO
http://archimer.ifremer.fr/doc/00157/26783/24884.pdf
http://archimer.ifremer.fr/doc/00157/26783/

Éditeur(s) : Elsevier
Résumé : A coupled three-dimensional physical-biogeochemical model was developed in order to simulate the ecological functioning of the Rio de la Plata estuary and plume. The biogeochemical model reproduces the nitrogen cycle between five compartments: dissolved inorganic nitrogen, phytoplankton, zooplankton, detritus and dissolved organic nitrogen. The coupling is tested in seasonal climatological configurations and for the particular year 1999. The circulation is forced with Parana and Uruguay rivers discharges, NCEP wind and tide. The biogeochemical model includes loads of inorganic and organic nitrogen from both rivers. The model reproduces the correct tidal amplitudes in the estuary, as well as the most outstanding features of the observed horizontal and vertical structures of the salinity plume. Simulated surface chlorophyll a concentrations exhibit maximum values all year long seaward of the turbidity front, between the 0.5 and 15 isohalines, in agreement with SeaWiFS images of the area. The model simulates well the low primary production in the light-limited highly turbid tidal river (20 gC/m(2)/yr), the high production area in the frontal zone where it can reach 500 gC/m(2)/yr, and the nutrient-limited production in the outer estuary and inner shelf (300 gC/m(2)/yr), with realistic values in each case. According to the 1999 model simulation, the tidal river is the location of organic nitrogen remineralization with a consequent increase of the inorganic pool. At the entrance of the frontal zone, inorganic nitrogen represents about 75% of the whole nitrogen pool, it is reduced to 50% at its sea end-member. The outer estuary has the same sink role for inorganic nitrogen, suggesting that organic nitrogen is the major form exported to the shelf.
Continental Shelf Research (0278-4343) (Elsevier), 2005-03 , Vol. 25 , N. 5-6 , P. 629-653

Droits : 2004 Elsevier Ltd.
http://archimer.ifremer.fr/doc/2005/publication-334.pdf
DOI:10.1016/j.csr.2004.10.003
http://archimer.ifremer.fr/doc/00000/334/

Éditeur(s) : HAL CCSD
Résumé : International audience
The Heliosat-II method was developed to process Meteosat satellite images in order to assess the solar irradiation at surface. It is modified for its use with GOES satellite images in order to estimate the solar irradiation over French Guiana.Modifications include a change in the calibration formula, in the calculation of the cloud albedo, and in the values of the Linke turbidity factor. These modifications allow the improvement of the performances of the Heliosat-II model in Intertropical zones in French Guiana. The outcomes were compared to coincident measurements of hourly irradiation performed by ground stations.The results show that the use of the maximum apparent albedo as the cloud albedo (ρcmax), along with a fixed value of the Linke turbidity factor produces the best results; the bias was less than 23.61 Wh/m2 (5% of the mean value of the measurements) overall, and the RMSE was less than 109.39 W/m2 (24%) overall when using hourly values. In the case of daily means, the RMSE drops to less than 10.08 W/m2 (10%) overall, whereas the overall bias remains unchanged, as expected. The model performs better in clear skies than in cloudy skies. The results suggest that the Linke turbidity factor used in the Heliosat-II method does not reproduce well the attenuation of the solar radiation in French Guiana. The results were compared to those obtained from Heliosat II method and Meteosat images (HelioClim-3 database) and we found a better accuracy for GOES satellite data, which exhibits smaller viewing angle. The use of the Heliosat II method with GOES images allows assessment of the SSI with a good accuracy and high temporal and spatial resolutions.
Canadian Journal of Remote Sensing

meteo-01304576
https://hal-meteofrance.archives-ouvertes.fr/meteo-01304576
DOI : 10.1080/07038992.2015.1040876

Éditeur(s) : Elsevier Science Bv
Résumé : The Var turbiditic system located in the Ligurian Sea (SE France) is an intermediate mud/sand-rich system. The particularity of the Var deep-sea fan is its single channel with abrupt bends and its asymmetric and hyper-developed levee on the right hand side: the Var Sedimentary Ridge. Long-term sediment accumulation on the Var Sedimentary Ridge makes this an ideal target for studying the link between onshore climate change and deep-sea turbidite stratigraphy. This paper focuses on the establishment of the first detailed stratigraphy of the levee, which is used to analyze the timing of overbank deposition throughout the last deglaciation. Main results indicate that high variability in turbidite frequencies and deposition rates along the Var Sedimentary Ridge are determined by two main parameters: 1) the progressive decrease of the levee height controlling the ability of turbidity currents to spill out from the channel onto the levee, and 2) climatic variations affecting the drainage basin, in particular changes in glacial condition since late Last Glacial Maximum to early Holocene. Compared to other deep-water areas, this study confirms the ability of turbiditic systems to record past climatic events on millennial timescales, and underlines the influence of European deglaciation on the observed decrease in turbidite activity in the Var canyon. The presence of a very narrow continental shelf and a single, large channel-levee system makes the Var Sedimentary Ridge a unique example of climate-controlled turbiditic accumulations. (C) 2010 Elsevier B.V. All rights reserved.
Marine Geology (0025-3227) (Elsevier Science Bv), 2011-01 , Vol. 279 , N. 1-4 , P. 148-161

Droits : 2010 Elsevier Ltd All rights reserved.
http://archimer.ifremer.fr/doc/00030/14104/11370.pdf
DOI:10.1016/j.margeo.2010.10.021
http://archimer.ifremer.fr/doc/00030/14104/

Éditeur(s) : HAL CCSD American Geophysical Union (AGU)
Résumé : International audience
This paper presents a new balanced structural cross-section of the Jaca thrust-sheet-top basin of the southern Pyrenees combined with paleo-thermometry and apatite fission track (AFT) thermochronology data. The cross-section, based on field data and interpretation of industrial seismic reflection profiles, allows refinement of previous interpretations of the south-directed thrust system, involving the identification of new thrust faults, and of the kinematic relationships between basement and cover thrusts from the middle Eocene to the early Miocene. AFT analysis shows a southward decrease in the level of fission track resetting, from totally reset Paleozoic rocks and lower Eocene turbidites (indicative of heating to Tmax > ~120 °C), to partially reset middle Eocene turbidites and no/very weak resetting in the upper Eocene-lower Oligocene molasse (Tmax < ~60 °C). AFT results indicate a late Oligocene-early Miocene cooling event throughout the Axial Zone and Jaca Basin. Paleo-maximum temperatures determined by vitrinite reflectance measurements and Raman spectroscopy of carbonaceous material reach up to ~240 °C at the base of the turbidite succession. Inverse modelling of AFT and vitrinite reflectance data with the QTQt software for key samples show compatibility between vitrinite-derived Tmax and the AFT reset level for most of the samples. However, they also suggest that the highest temperatures determined in the lowermost turbidites correspond to a thermal anomaly rather than burial heating, possibly due to fluid circulation during thrust activity. From these results, we propose a new sequential restoration of the south Pyrenean thrust system propagation and related basin evolution.
ISSN: 0278-7407

insu-01312746
https://hal-insu.archives-ouvertes.fr/insu-01312746
https://hal-insu.archives-ouvertes.fr/insu-01312746/document
https://hal-insu.archives-ouvertes.fr/insu-01312746/file/Labaume_et_al-2016-Tectonics.pdf
DOI : 10.1002/2016TC004192

Éditeur(s) : Elsevier
Résumé : High-resolution sedimentological and micropaleontological studies of several deep-sea cores retrieved from the levees of the Celtic and Armorican turbidite systems (Bay of Biscay - North Atlantic Ocean) allow the detection of the major oscillations of the British-Irish Ice Sheet (BIIS) and 'Fleuve Manche' palaeoriver discharges over the last 30,000 years, which were mainly triggered by climate changes. Between 30 and 20 cal ka, the turbiditic activity on the Celtic-Annorican margin was weak, contrasting with previous stratigraphic models which predicted a substantial increase of sediment supply during low sea-level stands. This low turbidite deposit frequency was most likely the result of a weak activity of the 'Fleuve Manche' palaeoriver and/or of a reduced seaward transfer of sediments from the shelf to the margin. However, two episodes of turbiditic activity increase were detected in the Celtic-Armorican margin, during Heinrich events (HE) 3 and 2. This strengthening of the turbiditic activity was triggered by the meltwater releases from European ice sheets and glaciers favouring the seaward transfer of subglacial material, at least via 'Fleuve Manche' palaeoriver. At around 20 cal ka, a significant increase of turbidite deposit frequency occurred as a response to the onset of the last deglaciation. The retreat of the European ice sheets and glaciers induced a substantial increase of the 'Fleuve Manche' palaeoriver discharges and seaward transfer of continentally-derived material into the Armorican turbidite system. The intensification of the turbiditic activity on the Celtic system was directly sustained by the widespread transport of subglacial sediments from the British-Irish Ice Sheet (BIIS) to the Celtic Sea via the Irish Sea Basin. A sudden reduction of turbiditic activity in the Armorican system, between ca. 19 and 18.3 cal ka, could have been triggered by the first well known abrupt sea-level rise ('meltwater pulse', at around 19 cal ka) favouring the trapping of sediment in the 'Fleuve Manche' palaeoriver valleys and the decrease of the seaward transfer of continentally-derived material. The maximum of turbiditic activity strengthening in the Celtic-Armorican margin, between ca. 18.3 and 17 cal ka, was induced by the decay of European ice sheets and glaciers producing the most extreme episode of the 'Fleuve Manche' palaeoriver runoff and a great seaward transfer of subglacial material into the Bay of Biscay, Between ca. 17.5 and 16 cal ka, the turbiditic activity significantly decreased in both Celtic and Armorican turbidite systems in response to a global re-advance of glaciers and ice sheets in Europe. The last episode of ice sheet retreat, between ca. 16 and 14 cal ka, is well expressed in the Celtic system by a new increase of the turbiditic activity. The major episode of sea-level rise at around 14 cal ka ('Meltwater Pulse 1A'), precluding the seaward transfer of sediments, induced the end of turbiditic activity in both the Celtic and the Armorican system. Although two main phases of global sea-level rise seem to have had an effect on the Celtic-Armorican margin, this work proposes the BUS retreat and associated riverine discharges as the main trigger mechanisms of the turbiditic activity in this region during the last 30,000 years.
Marine Geology (0025-3227) (Elsevier), 2008 , Vol. 247 , N. 1-2 , P. 84-103

Droits : 2008 Elsevier B.V. All rights reserved
http://archimer.ifremer.fr/doc/2008/publication-3729.pdf
DOI:10.1016/j.margeo.2007.08.006
http://archimer.ifremer.fr/doc/00000/3729/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The Taiwan area, where the Philippine Sea Plate collides with Eurasia, is one of the most seismically active areas in the world and has been consequently struck repeatedly by destructive earthquakes. To better constrain the occurrence of large earthquakes, we have conducted two cruises in 2012 and 2013 from which five piston, gravity and box-cores were retrieved from selected sites in targeted areas that contain continuous and accurate turbidite deposition offshore eastern Taiwan. Forty-seven turbidite layers deposited between 675 BC and 2012 AD have been described in the cores with facies varying from silty clay to coarse sand. We modeled each turbidite layer using the sedimentation rate deduced from radiocarbon age measurements performed on planktonic foraminifers. Precise dating based on 210Pb–137Cs chronology provided ages for the XXth century turbidites. Coring sites' locations, biotic association within turbidites beds and seismic calibration over the instrumental period, suggest that earthquakes are the most likely triggering mechanisms of turbidity currents over the last 2700 years. Calibration of correlations between turbidites and instrumental earthquakes allowed us to determine the minimum magnitude of recorded events (Mw = 6.8) and the maximum distance between the epicenter and the slope failure. Turbidites' synchroneity between cores has been tested but results showed that this criterion cannot be used in our study area because of the high level of seismicity, i.e., a M > 6.8 earthquake recurrence interval much smaller than the uncertainty on radiocarbon ages. The excellent accuracy of dating allows correlating all the turbidites deposited since 1920 with instrumental earthquakes. For each core, we established a return time ranging between 112 and 147 years for the period pre-1900 and ~ 27 and 34 years for the period post-1900. The discrepancy between pre-1900 and post-1900 recurrence either suggests, that slope stability varies, with higher slope instability after 1900 possibly due to increased sediment delivery by rivers.
ISSN: 0040-1951

hal-01467627
https://hal.archives-ouvertes.fr/hal-01467627
DOI : 10.1016/j.tecto.2016.04.030

Éditeur(s) : HAL CCSD
Résumé : Satellite and in situ chlorophyll concentration data collected as part of VALidation HYperspectral of a BIOgeochemical model (ValHyBio), a PNTS-sponsored project dedicated to satellite ocean-colour imaging of the Southwest Pacific, are analyzed to describe chlorophyll variability in the Coral Sea, a vast oligotrophic region characterized by a deep chlorophyll maximum and blue waters of high transparency. Average chlorophyll concentrations estimated from MODIS-Aqua are very low (<0.2 mg m-3) except in the vicinity of main islands and coral reefs, where enrichment may occur due to upwelling or internal waves that bring nutrients to the euphotic zone from the deep part of the water column. During the summer season, blooms of cyanobacteria (Trichodesmium) develop in the surface waters and may form large slicks. The nitrogen fixed by these slicks is a potential source of new nitrogen later assimilated by picoplankton and the marine food chain. Coastal areas exhibit higher chlorophyll concentrations because of nutrient input from the land, as observed in 2008 around New Caledonia. In lagoon areas, the sea colour is influenced by turbidity and bathymetry, and the MODIS OC3 algorithm is inadequate, with a systematic overestimation of chlorophyll concentration in the New Caledonia lagoon. Improved bio-optical algorithms are needed for those turbid and shallow waters, to allow not only a better description of chlorophyll variability, but also evaluation of chlorophyll simulations by recently developed biogeochemical models.
of the 12th International Coral Reef Symposium, 18E
CAIRNS, Australia

hal-00746470
https://hal.archives-ouvertes.fr/hal-00746470
https://hal.archives-ouvertes.fr/hal-00746470/document

Éditeur(s) : Elsevier Science Bv
Résumé : The Danube River Basin–Black Sea area represents a unique natural laboratory for studying the interplay between lithosphere and surface as well as source to sink relationships and their impact on global change. This paper addresses some information on the “active sink” of the system; i.e. the Danube deep sea fan and the Black Sea basin. The present study focuses on the distal sedimentary processes and the evolution of sedimentation since the Last Glacial Maximum. This is investigated through recently acquired long piston coring and shallow seismic data recovered at the boundary of influence of the distal part of the Danube turbidite system (to the north-west) and the Turkish margin (to the south). This dataset provides a good record of the recent changes in the sedimentary supply and climato-eustasy in the Black Sea region during the last 25 ka. This study demonstrates that the deep basin deposits bear the record of the Late Quaternary paleoenvironmental changes and that the western Black Sea constitutes an asymmetric subsident basin bordered by a northern passive margin with confined, mid-size, mud-rich turbidite systems mainly controlled by sea-level, and a southern turbidite ramp margin, tectonically active. Highlights ► Oceanographic results from survey carried out in the western Black Sea are presented. ► The Danube fan distal part: the Black Sea main depositional feature is described. ► This study is on the morphology and gravity sedimentation in the Black Sea deep basin. ► Data were collected at the boundary between the Danube fan and the Turkish margin. ► The dataset provide a good record of sedimentary supply and climato-eustatic changes.
Global And Planetary Change (0921-8181) (Elsevier Science Bv), 2013-04 , Vol. 103 , P. 232-247

Droits : 2012 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/00095/20637/18272.pdf
DOI:10.1016/j.gloplacha.2012.05.002
http://archimer.ifremer.fr/doc/00095/20637/

Éditeur(s) : Elsevier Science Bv
Résumé : The timing, routing and processes of sediment transfer from the continents to the oceans at millennial time-scale are still largely unknown. The potential of turbidite systems (dominantly deposited during sea-level lowstands) to record global or regional environmental fluctuations is usually under-exploited because of the difficulty to obtain robust chronostratigraphic constraints in turbiditic deposits, and therefore to tie changes in sedimentary processes to environmental fluctuations. We were able to obtain a millennial-scale chronostratigraphy based on oxygen isotopes of the scarce foraminifera preserved in turbiditic deposits of the Rhone Turbidite System within the Western Mediterranean. Our results show that 1) objective criteria can be defined for the selection of foraminifera preserved within the pelagic intervals between the turbiditic sequences, in order to obtain a reliable isotope stratigraphy; 2) Turbidites triggered by hyperpycnal currents are described for the first time within the Rhone Turbidite System. They are related to the periods of direct fluvial connection with the canyon head (during the sea-level lowstand and early rise), and to a period of high sediment flux in relation with the massive recession of the Rhone glaciers in the Alps; 3) The lithofacies change passing from hyperpycnal to “Bouma-type” is dated at ca 19 cal. ka BP, which might correspond to an acceleration of sea-level rise (19-ka Meltwater Pulse,).
Sedimentary Geology (0037-0738) (Elsevier Science Bv), 2015-06 , Vol. 323 , P. 148-166

Droits : 2015 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/00266/37712/35730.pdf
DOI:10.1016/j.sedgeo.2015.04.009
http://archimer.ifremer.fr/doc/00266/37712/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Reef positions record the interaction between eustasy and tectonics, and have been used worldwide to characterize vertical deformations of upper-plates at different time-scales and constrain the seismic behavior of megathrusts. Along the Lesser Antilles volcanic arc, high-resolution marine geophysical data were collected on the 2–20 km wide eastern Martinique reef platform to reconstruct its stratigraphic and morphologic history, and understand the influence of local normal faulting, volcanism and plate-scale subduction processes on Holocene and Late Pleistocene reef development. The subsiding Martinique platform's stratigraphy is composed of multiple superimposed sea-level highstand deposits separated by subaerial exposure surfaces of sea-level low stands. The carbonate platform consists of two laterally-extensive carbonate units (unit U2 overlying unit U3) that extend to the platform edge to a depth of − 95 m MSL (mean sea level), and form two morphologic terraces, M2 and M3 respectively. The landward portion of unit U2 is partially overlain between 0 and − 60 m MSL by the living reef tract U1. The current reef is composed of a landward fringing reef, a lagoon and a seaward barrier reef, the latter forming a double-bank barrier around the Caravelle Peninsula. In near-shore multi-channel seismic profiles, a distinct reflector at ~− 35 m MSL, probably a subaerial exposure surface E1, separates the reef sequence formed during the last transgression from a Pleistocene fossil reef tract forming unit U2. Offshore of Mount Pelée volcano (Late Pleistocene), the Holocene reef did not develop above unit U2, whose upper surface is incised by channels and apparent sinkholes. During the Holocene transgression, the possibility of excessive turbidity due to volcanic activity may have inhibited reef development in this area. The un-dated unit U2 probably developed 120–130 ka ago during the last interglacial (MIS 5.5) + 6 m MSL highstand as thick, extensive reefs deposited all along the Lesser Antilles arc. Due to subsidence, MIS 5.5 reefs are not represented by onshore facies, except along the southern Sainte Anne Peninsula where normal faulting and uplift balances island-scale subsidence. Based on unit U2's present elevation and assuming an MIS 5.5 age and + 6 m MSL sea level, Martinique has subsided at maximum 0.3 m/ky, likely due to subduction processes that question the coupling state of the megathrust.
ISSN: 0025-3227

hal-01307036
https://hal.archives-ouvertes.fr/hal-01307036
DOI : 10.1016/j.margeo.2015.08.001

Éditeur(s) : Elsevier Sci Ltd
Résumé : A detailed morphological analysis of the outer shelf and continental slope of the Western Gulf of Lion is presented, based on swath bathymetry data together with sub-bottom profiles and high resolution seismic reflection profiles. These data reveal two main erosive features, of very different dimensions: the axial incision and the canyon's major valley. The height of axial incisions' flanks with respect to the canyon deepest point (the thalweg) ranges from 40 to 150 m. It creates a small axial erosive path within the canyon's major valley, which is typically bounded by flanks of more than 700 m in height. We interpret the axial incision observed in the sea floor as the imprint of turbidity currents that eroded the floor of canyons during phases of connection to rivers (hyperpycnal turbidity current). Such currents are most likely to have formed during the Last Glacial Maximum (LGM) as both proximity of the shoreline (due to the lowstand of sea level) and high detrital sediment supply (due to glacial abrasion upstream) increased the flow of sediments delivered to the canyon heads. Fossil axial incisions, observed in seismic lines, are related to equivalent conditions. The axial incision, however, has a key influence on canyon evolution as it triggers mass wasting of different sizes that affect the canyon's major valley (head and flanks). We interpret the geometry of the canyon's major valley as the result of recurrent activity of axial incisions. These periods of activity occurred during low sea levels at glacial maxima and show a cyclicity of 100,000 years for the last 400,000 years.
Marine And Petroleum Geology (0264-8172) (Elsevier Sci Ltd), 2005-06 , Vol. 22 , N. 6-7 , P. 805-826

Droits : 2005 Elsevier Ltd All rights reserved
http://archimer.ifremer.fr/doc/2005/publication-353.pdf
DOI:10.1016/j.marpetgeo.2005.03.011
http://archimer.ifremer.fr/doc/00000/353/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The Miradouro da Lua cliffs, which are 60 km south of Luanda, record the building and uplift of the late Neogene Palaeo-Cuanza delta. The detailed study of the sedimentary architecture and stacking pattern permitted separation of the pile into five depositional units bounded by erosional surfaces and characterised by separate facies associations (genetic sequences = units in this paper). At the base of the series, aeolian deposits (Unit 1) mark the development of a possible coastal desert during the late Miocene aridification. The major Pliocene sea-level rise (Transgressive Systems Tract) led to the drowning of the continental platform into a discrete shoreface-foreshore sequence (Unit 2), followed by an expanded deltaic sequence (Unit 3) that represents the main outcrop of the area. The sedimentary fabric of this prograding wedge during the Highstand Systems Tract reveals laterally stacked pluri-hectometic mouth bars built by the abrupt switching of a bird-foot delta during the Pliocene highstand. The clinoforms are deeply incised by submarine gullies filled both by periodic river-driven turbidite and tidal currents (Unit 4) during the coeval growing of the delta. The topset of the prograding wedge and associated gullies infill is truncated by an overall erosional unconformity that marks the widespread development of an extensive braid-delta system (Unit 5) during the lower Pleistocene sea-level drop (Lowstand Systems Tract). The last 6 m of the Braid-delta unit is overprinted by a ferallitic profile, forming the surface of the plateau and indicating long-term subaerial exposure and weathering processes consistent with the maximum warming of the middle to late Pleistocene interglacial periods. The successive abrupt shifts of the depositional systems through the sedimentary pile indicate a high-amplitude sea level amplified by major coastal uplifts and the reorganisation of the fluvial network. In this context, the palaeo-Cuanza prograding wedge signals the westward tilting and 60 m total uplift of the coastal plain during the Pliocene. A new uplift pulse by differential tilt and slope increase is deduced from the widespread development of the braid-delta complex during the early Pleistocene. The last tectonic event corresponds to the 80- to 100-m uplift and ferallitic paedogenesis during the middle to late Pleistocene interglacial stages.
ISSN: 0899-5362

hal-01053716
https://hal.archives-ouvertes.fr/hal-01053716
DOI : 10.1016/j.jafrearsci.2014.01.013

Éditeur(s) : Springer Berlin / Heidelberg
Résumé : The role of particles in the fate and speciation of trace metals in macrotidal estuaries was studied using a surface complexation model (MOCO). Cadmium was selected as the target metal contaminant due to its reactivity in estuaries: cadmium behavior is mainly controlled by heterogeneous processes (sorption/desorption) related to salinity and suspended matter gradients. Various scenarios of suspended matter distribution according to salinity were simulated. The impact of surface properties (specific surface area, density of surface sites, acido-basic properties, and complexation constant) was evaluated using data collected on particles from the Gironde, Loire, and Seine estuaries. Our results show that particle surface properties, evaluated on the basis of various parameters, are instrumental in "non-conservative" contaminant speciation in the estuarine environment. Their evaluation enables us to understand and simulate, to a large extent, the fate of "Cd-type" contaminants (whose behavior is controlled by competition between sorption and desorption processes). The natural variations of these properties can be responsible for significant modifications of the Cd speciation in the macrotidal estuaries where salinity and SM gradients are very strong.
The Handbook of Environmental Chemistry (1433-6839) (Springer Berlin / Heidelberg), 2006 , Vol. 5H , P. 265-301

Droits : 2006 Springer
http://archimer.ifremer.fr/doc/2006/publication-2005.pdf
DOI:10.1007/b89479
http://archimer.ifremer.fr/doc/00000/2005/

Éditeur(s) : HAL CCSD
Résumé : Fault zones are major discontinuities in sedimentary basins. Understanding their role on fluid migrations is an essential issue to (i) characterize the mechanisms and kinematics of deformation and (ii) to determine the parameters which control the distribution of energetic or mineral resources. This work applies to faulting under a temperature range of 200-250°C, corresponding to that of deeply buried reservoirs as well as potentially seismogenic fault zones. The studied faults are normal faults affecting the “Grès d’Annot” Formation, a Priabonian-Rupelian siliclastic turbidite succession of the Alpine foreland basin. They are located in two distinct areas: the Moutière-Restefond area in the eastern part of the basin and the Estrop area in the western part. Vitrinite reflectance outside fault zones indicates maximal temperatures of 240-260°C at Moutière-Restefond and 170-200°C at Estrop, i.e. burial depths around 8 km and 6 km, respectively, assuming a mean geothermal gradient of 30°C/km. Burial was due to underthrusting below the Embrunais-Ubaye Alpine nappes, the difference in burial between the two areas traducing the westward taper of the nappe front.The studied faults affect alternating arkosic sandstone beds and pelite layers with offsets from centimeters to decameters. Two types of core zones are recognized: (1) the foliated core zones of the Moutière-Restefond area, where deformation dominated by pressure solution and synkinematic phyllosilicate neoformation resulted in a foliated fabric, and (2) the core zones of the Estrop area, characterized by dilatant quartz-mineralized veins and breccia. Fault and host rock petrophysical properties were measured on drill plugs, using the water porosity technique and nitrogen permeability technique under 2 Mpa of confining pressure. In the Moutière-Restefond fault zones, plug axes were oriented in three orthogonal directions corresponding to the main deformation axes (X, Y, Z) of the foliated arkose to characterize the effect of structural anisotropy. In the Estrop fault zones, where deformation does not show equivalent anisotropy, the plug axes were oriented according to the main fault plane orientation (i.e., parallel to azimuth, parallel to dip and normal). In each fault zone, the porosity of fault rocks is equivalent to that of host rocks. In the Moutière-Restefond fault zones, the plugs parallel to the X and Z axes of deformation have a permeability similar to that of the host rocks, whereas permeability parallel to the Y axis (i.e. parallel to the foliation and the main fault plane) is one order of magnitude higher. By contrast, the permeability values in the Estrop fault zones are isotropic and equivalent to the host rock values. This study highlights the importance of various types of deformation mechanisms and related fluid-rock interactions in determining different fault rock types within a similar protolith, ultimately controlling distinct petrophysical properties of fault zones.
Les zones de failles constituent des discontinuités majeures dans la croûte supérieure. Ce mémoire s’intéresse aux failles actives à des profondeurs de 5-8 km, i.e. dans des conditions pouvant jouer un rôle important (i) sur le comportement mécanique de de la croûte, en particulier sur son potentiel sismogénique et (ii) sur la compartimentation des réservoirs géologiques profondément enfouis.Les failles étudiées sont des failles normales (rejet jusqu’à 50 mètres) affectant des alternances de bancs de grès arkosiques et de pélites dans les Grès d’Annot, une formation turbiditique d’âge priabonien-rupélien du bassin d’avant-chaine alpin. Les Grès d’Annot ont été enfouis sous les nappes de l’Embrunais-Ubaye peu de temps après leur dépôt et exhumés au Miocène moyen-supérieur. L’étude a été réalisée dans deux secteurs des Alpes de Haute-Provence, (1) le secteur de l’Estrop (chaine des Trois Evéchés, dans la partie occidentale du bassin) et (2) le secteur de Point Vert-Restefond (alentours du col de la Bonette, dans la partie orientale du bassin). La réflectance de la vitrinite dans les Grès d’Annot indique des températures maximales de 160-190°C dans le secteur (1) et de 240-260 °C dans le secteur (2) , soit des profondeurs d’enfouissement de 5-6 km et 8-10 km, respectivement, dans l’hypothèse d’un gradient géothermique moyen de 25-30°C/km. A partir des observations microstructurales, de données d’inclusions de fluides, de modélisations thermodynamiques sur chlorites syncinématiques et des indices de cristallinité de l’illite, on a établi que les failles du secteur (1) ont fonctionné à une température d’environ 200°C pour une pression de 0.6Kbar et celles du secteur (2) dans une gamme de température de 200-220°C et de pression comprise entre 0.6 et 1.1 Kba. L’activité de la faille de Point-Vert a été datée par la méthode 40Ar/39Ar au Miocène inférieur (21 Ma). Ces failles sont interprétées comme associées aux premiers stades du soulèvement résultant de l’activité des chevauchements dans le socle sous-jacent.Deux types principaux de roches de failles caractérisent les failles étudiées. Les brèches dilatantes sont majoritaires dans les zones de failles du secteur (1) alors que les arkoses foliées sont majoritaires dans les zones de failles du secteur (2). Les brèches dilatantes témoignent de mécanismes de déformation dominés par la fracturation transgranulaire et la pression-solution des silicates. Ce dernier mécanisme se manifeste principalement par d’abondantes précipitations cycliques de quartz, les stylolites restant peu développés. Les géométries structurales sont associées à l’activation de plans T de Riedel déterminant l’ouverture de relais extensifs et un régime localement dilatant. Nous associons ce type de roche de faille à une faible pression effective au cours de la déformation.La déformation cisaillante exprimée dans les arkoses foliées témoigne de mécanismes de déformation dominés par (i) la fracturation intragranulaire et transgranulaire, (ii) la pressionsolution/ précipitation des silicates, principalement le quartz, (iii) la néoformation de micas blancs liée à l’altération des feldspaths et (iv) la précipitation de chlorite. Ce travail montre également que les transformations minéralogiques liées aux interactions fluide-roche dans la zone de faille (forte augmentation de la proportion des phyllosilicates au dépend des feldspaths) changent radicalementla composition minéralogique de la roche. Nous associons ce type de roche de faille à une forte pression effective au cours de la déformation.La pétrophysique montre que les brèches de failles (secteur 1) ont une perméabilité isotrope et équivalente à celle du protolithe (10-3mD sous 2 MPa de confinement) tandis que les roches foliées (secteur 2) montrent une augmentation de perméabilité (10-2mD) selon l’axe Y de la déformation, d’un ordre de grandeur supérieure aux perméabilités suivant les axes X et Z et dans la roche hôte (10-3mD). Ce drain préférentiel potentiel est associé à l’orientation des phyllosilicates dans la foliation.
https://hal.archives-ouvertes.fr/tel-01310382

tel-01310382
https://hal.archives-ouvertes.fr/tel-01310382
https://hal.archives-ouvertes.fr/tel-01310382/document
https://hal.archives-ouvertes.fr/tel-01310382/file/Th%C3%A8seCAVAILHES2012.pdf