Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The In-Ezzane volcanic district (EZD), located at the triple junction of Algeria, Niger and Libya belongs to the Eastern Hoggar, covers 350 km2 and includes 9 volcanic edifices that are probably aligned along NW-SE faults, parallel to the Tafassasset valley. The low volume (0.7 and 1 km3) of emitted lavas, the similar morphology of the monogenic cones and the lack of differentiated rocks indicate that the volcanic activity of the EZD was restricted in time and volume. The new K-Ar age (i.e. 2.86 ± 0.07 Ma) indicates that the EZD is contemporaneous with the last alkali volcanism paroxysm in Hoggar and with the nearby Libyan volcanics. The EZD alkali basalts (mainly basanite) show a remarkable homogeneous compositions both in major elements (44.8 ⩽ SiO2 ⩽ 45.8 wt.%; 5.2 ⩽ (Na2O + K2O) ⩽ 6.2 wt.%), trace elements (4.3 ⩽ Th ⩽ 5.5 ppm; 34.7 ⩽ La ⩽ 44.7 ppm; 16.1 < La/Yb(N) < 21.6) and radiogenic isotopes (0.70285 < 87Sr/86Sr < 0.70303; 0.51298 < 143Nd/144Nd < 0.51301; (19.212 < 206Pb/204Pb < 19.340, 15.589 < 207Pb/204Pb < 15.602 and 38.834 < 208Pb/204Pb < 38.903). Relative to the Hoggar alkaly basalts the EZD basalts appear systematically impoverished in incompatible elements and show a depleted signature both in Sr and Nd isotopes (almost MORB-like). The Pb isotopes are relatively enriched and intermediate between tholeiites and alkali basalts of the Hoggar. This unusual geochemical signature, is uneasy to reconcile with the known characteristics of the Hoggar swell, and would rather fingerprint a circum cratonic mantle lying beneath the west border of the Murzuq craton (Libya).
ISSN: 0899-5362

hal-01054340
https://hal.archives-ouvertes.fr/hal-01054340
DOI : 10.1016/j.jafrearsci.2013.12.001

Éditeur(s) : Springer
Résumé : Batch culture experiments using viral enrichment were conducted to test the response of a coastal bacterial community to autochthonous (i.e., co-existing) or allochthonous riverine viruses. The effects of viral infections on bacterial dynamics and activity were assessed by epifluorescence microscopy and thymidine incorporation, respectively, whereas the effect of viral infection on bacterial community composition was examined by polymerase chain reaction-single strand conformation polymorphism 16S ribosomal RNA fingerprinting. The percentages of high nucleic acid-containing cells, evaluated by flow cytometry, were significantly correlated (r (2) = 0.91, n = 12, p < 0.0001) to bacterial production, making this value a good predictor of active cell dynamics along the study. While confinement and temperature were the two principal experimental factors affecting bacterial community composition and dynamics, respectively, additions of freshwater viruses had significant effects on coastal bacterial communities. Thus, foreign viruses significantly reduced net bacterial population increase as compared to the enrichment treated with inactivated virus. Moreover, freshwater viruses recurrently and specifically affected bacterial community composition, as compared to addition of autochthonous viruses. In most cases, the combined treatment viruses and freshwater dissolved organic matter helped to maintain or even enhance species richness in coastal bacterial communities in agreement to the 'killing the winner' hypothesis. Thus, riverine virus input could potentially influence bacterial community composition of the coastal bay albeit with modest modification of bulk bacterial growth.
Microbial Ecology (0095-3628) (Springer), 2009-02 , Vol. 57 , N. 2 , P. 295-306

Droits : 2009 Springer
http://archimer.ifremer.fr/doc/2009/publication-6636.pdf
DOI:10.1007/s00248-008-9428-1
http://archimer.ifremer.fr/doc/00000/6636/

Éditeur(s) : Université de Bretagne Occidentale
Résumé : This activity report entitled (“Chemical contamination of the marine environment: from measurement to risk assessment”) summarizes the main stages my career at Ifremer from November 1975 to june 2013. The first chapter deals with the seawater chlorination and chlorinated waters released into the sea, the identification and the conditions of the formation of various by-product of these processes. The second chapter concerns PCBs, their nature, their chemical analysis in environmental matrices. PCBs are considered as the best examples of persistant and bioaccumulable compounds and therefore, in all this report they are flagship contaminants to which other groups of studied substances are compared. The third chapter refers to studies performed within marine pollution monitoring programme RNO (Réseau National d’Observation de la qualité de l’environnement marin - National observation network on the quality of the marine environnment) and well as other more limited studies like a first assessement on the presence of dioxins and dioxin-like PCBs in the French coastal marine environment and last, on the use of zebra mussel (Dresseinia polymorpha) as sentinelle species of the chemical contamination in the Seine estuary. The next two chapters are about bioaccumulation and about the distribution of organic contaminants (PCBs, dioxins, PAHs, PBDEs) in marine organisms and in marine foodwebs. These studies aim at a better knowledge of the presence and fate of these compounds in fish and marine organisms eitheir in an environmental perspective (chapter IV) or in order to contribute to the assessment of their health impact, or more precisely to estimate therelative part of fish and seafood to the human exposure to chemical residues (chapter V). To conclude, the chapter VI concerns the PCB and dioxin fingerprints in the various studied marine matrices ; analytical and environmental interpretations of the observed differences are suggested as well as possible applications.
Ce bilan d’activité intitulé « Contamination chimique du milieu marin : de la mesure à l’évaluation des risques » retrace les étapes essentielles de mon parcours à Ifremer entre novembre 1975 et juin 2013. Le premier chapitre traite de la chloration dans l’eau de mer et les rejets chlorés en mer, l’identification des sous-produits formés lors de ces traitements, les conditions de leur formation. Le second chapitre concerne la nature des PCB et leur analyse dans les matrices environnementales. Les PCB considérés comme les meilleurs exemples de composés persistants bioaccumulables constituent les « contaminants phares » de l’ensemble de ce travail et c’est par rapport aux PCB que sont comparés et évalués les autres groupes de contaminants étudiés. Le troisième chapitre se rapporte aux travaux réalisés dans le cadre de la surveillance RNO (Réseau National d’Observation de la qualité de l’environnement marin) ainsi que dans des études ponctuelles comme un premier inventaire sur les niveaux de présence des dioxines (PCDD et PCDF) dans l’environnement marin littoral ou sur l’utilisation de la moule zébrée (Dresseinia polymorpha) comme espèce indicatrice de la contamination de l’estuaire de la Seine. Les deux chapitres suivants sont consacrés aux travaux sur la bioaccumulation et aux contaminants organiques (PCB, dioxines, HAP, PBDE) dans les organismes et les réseaux trophiques marins soit dans une perspective environnementale sur le devenir des contaminants dans le vivant (chapitre IV) soit dans le cadre de l’évaluation des risques sanitaires ou, plus précisément, de l’estimation de la contribution de la consommation des produits de la mer à l’exposition de l’homme aux résidus chimiques (chapitre V). Pour terminer, le chapitre VI concerne les empreintes de PCB et de dioxines dans les différentes matrices étudiées ; une interprétation analytique et environnementale des différences observées est proposée ainsi que de possibles applications.

Droits : 2013 UBO
http://archimer.ifremer.fr/doc/00168/27946/26237.pdf
http://archimer.ifremer.fr/doc/00168/27946/

Éditeur(s) : HAL CCSD Elsevier
Résumé : Extracting and purifying a representative fraction of bacteria from soil is necessary for the application of many techniques of microbial ecology. Here the influence of different soil types on the quantitative and qualitative recovery of bacteria by soil grinding and Nycodenz density gradient centrifugation was investigated. Three soils presenting contrasted physicochemical characteristics were used for this study. For each soil, the total (AODC: acridine orange direct count) and culturable (cfu: colony-forming units) bacterial densities were measured in three distinct fractions: (i) the primary soil, (ii) the soil pellet (soil remaining after centrifugation), and (iii) the extracted cells. The automated-ribosomal intergenic spacer analysis (A-RISA) was used to characterize the community structure directly from the DNA extracted from each fraction. The physicochemical characteristics of soils were found to influence both the efficiency of bacterial cell recovery and the representativeness of the extracted cells in term of community structures between the different fractions. Surprisingly, the most representative extracted cells were obtained from the soil exhibiting the lowest efficiency of cell recovery. Our results demonstrated that quantitative and qualitative cell recovery using Nycodenz density gradient centrifugation are not necessarily related and could be differentially biased according to soil type.
ISSN: 1164-5563

hal-01031904
https://hal.archives-ouvertes.fr/hal-01031904
DOI : 10.1016/j.ejsobi.2005.08.003

Éditeur(s) : HAL CCSD Inter-Research
Résumé : Precise knowledge of lifetime migrations is vital in exploited fish species, since all essential habitats must be protected to maintain sustainable stock levels. The present study used multi-element otolith fingerprints of the gilthead sea bream Sparus aurata (L.) to discriminate its main juvenile and adult habitats in the Languedoc-Roussillon region (Gulf of Lions, northwest Mediterranean) and infer the lifetime migrations of 12 individuals from the area (11 from the present day and 1 from the Roman era). This allowed for the first time the identification of key habitats for the successful completion of the species' life cycle in the Gulf of Lions, and the connectivity between them. Our results revealed that lagoon use by S. aurata is probably ancient (>2500 yr) and confirmed its current commonness. Yet, although most observed migration patterns were in accordance with the migratory behavior previously described for the species, strong inter-individual variations and new patterns in habitat use were detected. At the juvenile stage, a preference for shallow lagoons with low salinities was evidenced. Nevertheless, the first year of life can also be successfully completed in marine conditions. At the adult stage, lagoon use was shown to occur until at least age 4 yr, with periods of lagoon residency of up to 11 mo in a year, often including winter months. Because overwintering in the lagoons was previously thought to be impossible for S. aurata due to low temperatures, this finding has important implications for future stock management, especially since the species breeds in winter.
Marine Ecology Progress Series

hal-00682003
https://hal.archives-ouvertes.fr/hal-00682003
DOI : 10.3354/meps09444

Éditeur(s) : HAL CCSD Ecological Society of America
Résumé : Reliable assessment of fish origin is of critical importance for exploited species, since nursery areas must be identified and protected to maintain recruitment to the adult stock. During the last two decades, otolith chemical signatures (or "fingerprints") have been increasingly used as tools to discriminate between coastal habitats. However, correct assessment of fish origin from otolith fingerprints depends on various environmental and methodological parameters, including the choice of the statistical method used to assign fish to unknown origin. Among the available methods of classification, Linear Discriminant Analysis (LDA) is the most frequently used, although it assumes data are multivariate normal with homogeneous within-group dispersions, conditions that are not always met by otolith chemical data, even after transformation. Other less constrained classification methods are available, but there is a current lack of comparative analysis in applications to otolith microchemistry. Here, we assessed stock identification accuracy for four classification methods (LDA, Quadratic Discriminant Analysis [QDA], Random Forests [RF], and Artificial Neural Networks [ANN]), through the use of three distinct data sets. In each case, all possible combinations of chemical elements were examined to identify the elements to be used for optimal accuracy in fish assignment to their actual origin. Our study shows that accuracy differs according to the model and the number of elements considered. Best combinations did not include all the elements measured, and it was not possible to define an ad hoc multielement combination for accurate site discrimination. Among all the models tested, RF and ANN performed best, especially for complex data sets (e. g., with numerous fish species and/or chemical elements involved). However, for these data, RF was less time-consuming and more interpretable than ANN, and far more efficient and less demanding in terms of assumptions than LDA or QDA. Therefore, when LDA and QDA assumptions cannot be reached, the use of machine learning methods, such as RF, should be preferred for stock assessment and nursery identification based on otolith microchemistry, especially when data set include multispecific otolith signatures and/or many chemical elements.
ISSN: 1051-0761

hal-00644549
https://hal.archives-ouvertes.fr/hal-00644549
DOI : 10.1890/09-1887.1

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
To understand the deep cycle of water, upper mantle water content and distribution between nominally anhydrous minerals (NAMs) and hydrous minerals (e.g., amphibole) must be constrained. We need then to understand H behaviour during mantle melting and metasomatism. Major, minor and trace element compositions including water contents were obtained on ten xenoliths of spinel-bearing peridotites from the Ray Pic locality, in the Southern part of the Massif Central (France). The sample suite investigated here is composed of rather fertile lherzolites (89.4 ≤ Fo ≤ 90.8%; 11.3 ≤ cr# in spinel ≤ 21.1%; 0.942 ≤ [Yb]cpx ≤ 1.90 ppm; cpx: clinopyroxene), which can be best explained by batch melting, with degree of melting between 3 and 10%. These xenoliths contain up to 8% modal amphibole. Three groups are defined as a function of the amphibole modal abundance (above or below 1%) and equilibrium temperature (above or below 1000 °C). Results show no clear positive correlation between modal metasomatism (amphibole) and incompatible element enrichment in cpx. Trace element compositions in cpx show strong enrichments of the most incompatible elements (e.g., (La/Sm)PM as high as 15.7; PM: normalised to primitive mantle values), but strong negative anomalies of the high field strength elements (e.g., (Th/Nb)PM as high as ~ 680). Such trace element fractionations are usually ascribed to the so-called carbonatitic metasomatism involving the percolation of small volume melts which are enriched in volatiles. The hydrogen concentrations in cpx range from 203 to 330 ppm wt. H2O, in orthopyroxene from 66 to 160 ppm wt. H2O and in olivine from 2 to 6 ppm wt. H2O. These values are within the common concentration range of other spinel-bearing peridotites. Amphiboles contain 1.9 ± 0.5 wt.% of H2O.The effect of metasomatism on water abundances in NAMs is not straightforward. Hydrous metasomatism (i.e., leading to the crystallisation of OH-bearing amphibole) has no effect on the water content of the co-existing NAMs. This suggests thus that the occurrence of hydrous minerals, such as amphibole, does not systematically imply that the coexisting NAMs are water-rich (saturated). Further, the percolation of volatile-rich small volume melts, which is fingerprinted by the strong enrichment of the incompatible elements, has also no clear effect on the water content of the NAMs. These data are thus difficult to reconcile with the admitted highly incompatible behaviour of H in upper mantle minerals.
ISSN: 0024-4937

hal-01278062
https://hal.archives-ouvertes.fr/hal-01278062
DOI : 10.1016/j.lithos.2015.08.013

Éditeur(s) : HAL CCSD
Résumé : International audience
More and more animal species are endangered. In order to study and protect them, several measures have been taken, which now seem to show their limit. This work focuses on the counting process, a key issue for any project that aims to protect animals. Indeed, this paper proposes an algorithm for automatic counting of singing birds in their habitat by using wireless sensors fitted with microphone. Sensors are used to record audio samples of bird songs. These samples are used to extract some kinds of song fingerprint that are thereafter used to recognize the bird species, through a classification process. Afterwards, by analyzing data which have been collected by a central base, the network structure derived from detection fields of sensors, allows our algorithm to propose an estimate of singing birds in the habitat. This paper details the counting algorithm which uses graph theory and audio inputs comparison. Finally, we demonstrate our scheme efficiency through experimentations.
Local Computer Networks (LCN)
Clearwater, United States

hal-00786165
https://hal.archives-ouvertes.fr/hal-00786165
DOI : 10.1109/LCNW.2012.6424060

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Recent geochemical work shows that subduction-zone serpentinites are repositories for fluid-mobile elements absorbed during interaction with sediment-derived fluids. Unraveling the geochemical fingerprint of these rocks helps to define timing of tectonic accretion of sediments along the subduction interface and the role of serpentinite in element recycling to volcanic arcs. Here we present the trace element and isotopic composition (B–O–H, Sr, Pb) of high-pressure serpentinites from the Voltri Massif (Ligurian Western Alps, Italy), to discuss their role as incompatible element carriers and their contribution to recycling of sediment-derived components in subduction zones.The serpentinites presented here record metamorphic olivine growth during eclogite-facies metamorphism and show undeformed and mylonitic textures. Field relations show that undeformed rocks are enclosed in deformed ones and that no metasedimentary rocks are present nearby. Undeformed serpentinite has very high δ11BSRM951 (from +26‰ to +30‰), low Sr and Pb isotope ratios (87Sr/86Sr = 0.7053–0.7069; 206Pb/204Pb = 18.131–18.205) and low As and Sb contents (0.1 and 0.01 μg/g, respectively). Oxygen and hydrogen isotope compositions are +4.5‰ and −67‰, respectively. In contrast, mylonitic serpentinite shows lower δ11B (from +22‰ to +17‰), significant enrichment in radiogenic Sr and Pb isotopes (87Sr/86Sr up to 0.7105; 206Pb/204Pb up to 18.725), and enrichment in As and Sb (1.3 and 0.39 μg/g, respectively). δ18O of the mylonitic serpentinites reaches values of +5.9‰, whereas δD is comparable with that of undeformed rocks (approximately −70‰). In mylonitic serpentinites, the B and Sr isotopic values and the fluid-mobile element (FME) concentrations are near those for the Voltri metasedimentary rocks (calc- and mica-schists). Pb systematics also reveal influx of a crust-derived component.Our dataset shows that undeformed serpentinite still preserves an oceanic geochemical fingerprint, whereas mylonitic serpentinite is reset in its concentrations of FME and its B, Sr and Pb isotope compositions, due to interaction with sediment- and crust-derived fluids. The environment of this interaction is either compatible with (i) an outer-rise zone setting, with percolation of seawater-derived fluids enriched in sedimentary components into bending-related fault structures, or with (ii) subduction channel domains, where ascending sediment-derived slab fluids infiltrate slices of former oceanic serpentinite accreted to the plate interface domain. Influx of sediment-derived subduction fluids along major deformation zones in serpentinite modifies the element budget of the rocks, with important implications for element recycling and the tectonic history of serpentinite. The B, Sr and Pb isotopic systematics, coupled with FME concentration in serpentinites are particularly helpful geochemical tracers of interaction between different reservoirs in subduction-interface environments, and are more sensitive than the traditionally applied stable oxygen and hydrogen isotope compositions.
ISSN: 0016-7037

hal-01419940
https://hal.archives-ouvertes.fr/hal-01419940
DOI : 10.1016/j.gca.2016.06.034

Éditeur(s) : HAL CCSD BioMed Central
Résumé : International audience
UNLABELLED: ABSTRACT: BACKGROUND: Genomics, transcriptomics and proteomics of glioblastoma multiforme (GBM) have recently emerged as possible tools to discover therapeutic targets and biomarkers for new therapies including immunotherapy. It is well known that macroscopically complete surgical excision, radiotherapy and chemotherapy have therapeutic limitations to improve survival in these patients. In this study, we used a differential proteomic-based technique (2D-Difference Gel Electrophoresis) coupled with matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry to identify proteins that may serve as brain tumor antigens in new therapeutic assays. Five samples of patients presenting a GBM and five samples of microscopically normal brain tissues derived from brain epileptic surgery specimen were labeled and run in 2D-PAGE (Two-Dimensional Polyacrylamide Gel Electrophoresis) with an internal pool sample on each gel. Five gels were matched and compared with DIA (Difference In-gel Analysis) software. Differential spots were picked, in-gel digested and peptide mass fingerprints were obtained. RESULTS: From 51 protein-spots significantly up-regulated in GBM samples, mass spectrometry (MS) identified twenty-two proteins. The differential expression of a selected protein set was first validated by western-blotting, then tested on large cohorts of GBM specimens and non-tumor tissues, using immunohistochemistry and real-time RT-PCR. CONCLUSIONS: Our results confirmed the importance of previously described proteins in glioma pathology and their potential usefulness as biological markers but also revealed some new interesting targets for future therapies.
ISSN: 1477-5956

inserm-00585020
http://www.hal.inserm.fr/inserm-00585020
http://www.hal.inserm.fr/inserm-00585020/document
http://www.hal.inserm.fr/inserm-00585020/file/1477-5956-9-16.pdf
DOI : 10.1186/1477-5956-9-16

Éditeur(s) : Elsevier Science Bv
Résumé : The main objective of this work was to establish the influence of sex, maturity and reproduction on the contamination of the demersal fish Merluccius merluccius by organochlorine compounds. Polychlorinated biphenyls (PCBs) and p,p'DDE were quantified in muscle, liver and gonads of female and male hakes collected in the Gulf of Lions in 2004 and 2005. Observed levels appeared higher than the population of the Bay of Biscay and lower than the population of the Thyrrenian Sea. Contaminant fingerprints were roughly constant whatever the studied organ and the hake biological condition. Concentrations varied significantly according to the sex and maturity of hakes. Mature specimens were more contaminated than immature, and males presented higher levels than females. This sex effect can be linked to a lower growth rate of males, and a contaminant elimination during female spawning. Gonadal contamination depends on the importance of lipid content and increases with the maturation degree. Although the main organ of energy and PCB storage is the liver, muscle appears as the main contributor to the gonad contamination. (C) 2009 Elsevier B.V. All rights reserved.
Science Of The Total Environment (0048-9697) (Elsevier Science Bv), 2009-12 , Vol. 408 , N. 2 , P. 304-311

Droits : 2009 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/00000/11129/9317.pdf
DOI:10.1016/j.scitotenv.2009.10.004
http://archimer.ifremer.fr/doc/00000/11129/

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
BACKGROUND: The use of pesticides and the related environmental contaminations can lead to human exposure to various molecules. In early-life, such exposures could be responsible for adverse developmental effects. However, human health risks associated with exposure to complex mixtures are currently under-explored. OBJECTIVE: THIS PROJECT AIMS AT ANSWERING THE FOLLOWING QUESTIONS: What is the influence of exposures to multiple pesticides on the metabolome? What mechanistic pathways could be involved in the metabolic changes observed? METHODS: Based on the PELAGIE cohort (Brittany, France), 83 pregnant women who provided a urine sample in early pregnancy, were classified in 3 groups according to the surface of land dedicated to agricultural cereal activities in their town of residence. Nuclear magnetic resonance-based metabolomics analyses were performed on urine samples. Partial Least Squares Regression-Discriminant Analysis (PLS-DA) and polytomous regressions were used to separate the urinary metabolic profiles from the 3 exposure groups after adjusting for potential confounders. RESULTS: The 3 groups of exposure were correctly separated with a PLS-DA model after implementing an orthogonal signal correction with pareto standardizations (R2 = 90.7% and Q2 = 0.53). After adjusting for maternal age, parity, body mass index and smoking habits, the most statistically significant changes were observed for glycine, threonine, lactate and glycerophosphocholine (upward trend), and for citrate (downward trend). CONCLUSION: This work suggests that an exposure to complex pesticide mixtures induces modifications of metabolic fingerprints. It can be hypothesized from identified discriminating metabolites that the pesticide mixtures could increase oxidative stress and disturb energy metabolism.
ISSN: 1932-6203

inserm-00863407
http://www.hal.inserm.fr/inserm-00863407
http://www.hal.inserm.fr/inserm-00863407/document
http://www.hal.inserm.fr/inserm-00863407/file/journal.pone.0064433.pdf
PUBMED : 23704985

Éditeur(s) : HAL CCSD
Résumé : International audience
A key issue for any project that aims to study endangered animals is the counting process. In this work, we propose an algorithm for automatic counting of singing birds in their habitat by using wireless sensors fitted with microphone. Sensors are used to record audio samples of bird songs and samples are analyzed to extract fingerprints that permit to recognize bird species. This paper details the counting algorithm that uses graph theory and audio inputs comparison. Finally, we demonstrate our scheme efficiency through experimentations.
International Symposium on a World of Wireless, Mobile and Multimedia Networks
Lucca, Italy

hal-00618563
https://hal.archives-ouvertes.fr/hal-00618563
DOI : 10.1109/WoWMoM.2011.5986215

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
We report on microstructural data obtained by optical microscopy and transmission electron microscopy concerning the crystallographic relationships of serpentine minerals with their host olivine in two contrasting situations. In the first case, mesh-textured lizardite (liz) is developed in a standard 60% serpentinized oceanic harzburgite from the Oman ophiolite where olivine converts to columnar lizardite. The joined columns are perpendicular to the basal plane (001)(liz), corresponding to the pseudofibres observed optically. The plane (001)(liz) is locally parallel to the narrow boundary ol-liz; thus column orientations register the interface of serpentinization. The ol-liz relationships are not strictly topotactic, but reflect preferred cracking orientations in olivine, parallel to (010)(ol). In the second case, antigorite (atg) develops in a rare sample of antigorite schist in a kimberlite from Moses Rock (Colorado Plateau), representative of a suprasubduction-zone mantle wedge. High-resolution transmission electron microscopy (HRTEM) images along [010](atg) show domains of very regular modulation with a 43 center dot 5 A wavelength (m = 17, where m is the number of silicate tetrahedra along the wave), with few defects, indicative of HP-HT antigorite, and also heavily kinked regions as fingerprints of strong tectonic shear. TEM imaging and electron diffraction patterns reveal two topotactic relationships between antigorite and olivine: [100](atg)//[010](ol) and < 100 >(atg)//< 100 >(ol); the planes in contact are (001)(atg)//(100)(ol) and (001)(atg)//(010)(ol), respectively. The [010](atg)//[001](ol) and antigorite lamellae are parallel to the forsterite b-axis. In both cases, the topography of olivine-serpentine interfaces is controlled by open fluid pathways along microcracks oriented according to the anisotropy of the olivine aggregate. In the cases studied, the serpentine aggregate exhibits a preferred orientation inherited from that of the peridotite. These results have some relevance to the seismic anisotropy of serpentinized mantle. Anisotropy of propagation of seismic waves as a result of the olivine fabric is maintained and reinforced with the development of lizardite. Conversely, the development of antigorite produces a trench-parallel fast S-wave polarization and an anisotropy that is lowered at low degrees of serpentinization and then increased with increasing serpentinization.
ISSN: 0022-3530

hal-00456061
https://hal.archives-ouvertes.fr/hal-00456061
DOI : 10.1093/petrology/egp049

Éditeur(s) : Oxford Univ Press
Résumé : In subduction zones, melting and dehydration of the subducted slab introduce material into the mantle wedge and modify its chemical and isotopic composition. As a consequence, island arc lavas differ significantly from mid-ocean ridge basalts and ocean island basalts. In some arcs, the composition of lavas is strongly influenced by the sedimentary material introduced with the slab; in others, magma composition is mainly affected by aqueous fluids released by the slab. The Lesser Antilles arc is known for its extreme continental-crust-like signature but for some Lesser Antilles lavas subducted sediments are barely involved and enrichment in fluid-mobile elements (Ba, U, Sr, Pb, etc.) is the dominant feature. Here we evaluate whether La/Sm is a quantitative proxy of sediment involvement in volcanic arcs, and we relate dehydration and melting processes to the temperature and pressure conditions of the slab. We use Martinique as a case study because in this island both dehydration and sediment melting fingerprints coexist. We measured major and trace elements for about 130 age-constrained samples, carefully chosen to cover all volcanic phases of Martinique (25 Ma to present). Using these results we demonstrate that: (1) weathering does not modify the La/Sm ratio; (2) fractional crystallization of amphibole and/or garnet does not increase La/Sm by more than 20%; (3) rare earth element transfer from wall-rock to magma during fractionation is not significant; (4) melting of the mantle source increases La/Sm by only about 20%. As a consequence, we show that the proportion of slab sediment incorporated in the mantle wedge controls the La/Sm ratio of the source. The observed correlations between La/Sm and Nd and Hf isotopic compositions indicate that the effect of sediment addition is the overwhelming factor: La/Sm is a good proxy for slab sediment proportion in Martinique. We observe a geographical gradient between slab dehydration and sediment melting on the island. Whereas lavas located on the western side of the island display a clear sedimentary input in their source, lavas located on the eastern side of the island, closer to the trench, are clearly influenced by dehydration of the subducted slab. In addition, the aqueous fluids clearly come from the subducted basalt and they did not interact with the overlying sediments. The influence of sediment added to the source of the magmas increases from the eastern part to the western part of the island. We relate this geographical change to the pressure and temperature conditions at the slab surface. Sediments probably cross their solidus under Martinique and hydrous melting is triggered. Finally, we show that under all volcanic arcs where the signature of sediments overwhelms the signature of fluids, the slab surface reaches P-T conditions that allow the subducted sediments to melt. Inversely, under most volcanic arcs where the signal of aqueous fluids dominates over sediment melts, the subducted slab is not hot enough for the sedimentary pile to melt.
Journal Of Petrology (0022-3530) (Oxford Univ Press), 2012-12 , Vol. 53 , N. 12 , P. 2441-2464

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00113/22392/20234.pdf
DOI:10.1093/petrology/egs055
http://archimer.ifremer.fr/doc/00113/22392/

Éditeur(s) : HAL CCSD Wiley-Blackwell
Résumé : International audience
Although lawsonite-bearing rocks are rare in exhumed high-pressure (HP) terranes, they are considered to exert a primary role in subduction dynamics. Recent observations in natural settings have shown that fluid–rock interaction at HP conditions, including metasomatism, may lead to unusually high lawsonite amounts even in rocks that originally contained little or no lawsonite. This process may therefore bear important implications for element recycling in subduction zones. A detailed characterization of the geochemical fingerprints associated with lawsonite metasomatism is presented in this contribution. The studied rocks belong to the HP terranes of Alpine Corsica (France), which is the largest documented exposure for lawsonite metasomatism. Metasomatic lawsonite displays complex compositional zoning, including high trace element, Cr and Ti content. The trace element content is much higher compared with the average of non-metasomatic lawsonite, and is in line with the re-incorporation of large amounts of trace elements (e.g. REE, Sr, Pb, Th) in the rock during metasomatism, as shown by mass transfer calculations. Our data suggest that serpentinites represented the main fluid source for the metasomatism, with concurrent contribution of other, possibly Ca-rich lithologies, such as mafic or meta-sedimentary rocks. We propose that the breakdown of metasomatic lawsonite may contribute to the genesis of magmas and their characteristic geochemical signatures.
ISSN: 0263-4929

hal-01107395
https://hal.archives-ouvertes.fr/hal-01107395
DOI : 10.1111/jmg.12074

Éditeur(s) : HAL CCSD ACM
Résumé : International audience
This study presents two algorithms that count birds with wireless sensors equipped with microphones. Audio inputs are parametrized to get some kind of fingerprints which are used to recognize the song of the birds in a classification process. Afterward, counting algorithms derive an estimate of the number of singing birds in the habitat. Unlike traditional approaches which leverage the audio waveform to get the location of the targets, we use a trilateration technique on graphs derived from the detection of the birds. These graphs exhibit nice properties which enable the finding of the estimate in polynomial time. Further, experiments are conducted and confirmm the efficiency of our counting algorithms even in the presence of noise.
Proceedings of the 6th ACM symposium on Performance evaluation of wireless ad hoc, sensor, and ubiquitous networks
New York, United States

hal-00602263
https://hal.archives-ouvertes.fr/hal-00602263
DOI : 10.1145/1641876.1641891

Éditeur(s) : HAL CCSD
Résumé : In Suriname, Saramaka (descendants from fugitives slaves of the XVIIth century) still have a widely used traditional pharmacopoeia. The Bitter-cup is a good example because of the place it keeps on the Paramaribo's markets stands. We conducted an ethnopharmacological study in order to detail its uses: rum or water left to macerate in the cup overnight, the content is drunk straight in the morning either as a tonic, stomachic, febrifuge or antimalarial remedy. In order to close the controversy about its botanical origin, we proceeded to an anatomical study of woods and cups found at the market. Chemicals fingerprints by High Performance Liquid Chromatography (HPLC) were simultaneously established. The two methods, complementary, allowed us to identify Quassia amara L. as cups source. In vitro assays of the macerates on Plasmodium falciparum did not show any antimalarial activity, while some fractions, obtained by semi-preparative HPLC, did show a high activity against parasites.
Les Saramaka du Suriname, descendants d'esclaves échappés des plantations au XVIIème siècle, ont une pharmacopée traditionnelle encore vive. Le Bitter-cup, ou " gobelet amer ", en est un exemple puisqu'il garde encore sa place sur les étals des marchés de Paramaribo. Nous avons mené une enquête ethnopharmacologique afin de détailler ses usages : mis à macérer pendant une nuit avec du rhum ou de l'eau, le contenu est bu d'un trait au matin comme tonique amer, stomachique, fébrifuge ou encore antimalarique. Pour mettre fin aux controverses que suscite sa provenance botanique, nous avons procédé à une étude anatomique du bois et des gobelets provenant du marché, ainsi qu'à l'établissement de signatures chimiques par Chromatographie Liquide Haute Performance (CLHP). Ces deux méthodes complémentaires nous ont permis d'identifier Quassia amara L. comme source des gobelets. Des tests in vitro sur Plasmodium falciparum n'ont pas confirmé l'activité antipaludique, mais après un fractionnement bioguidé par CLHP semi-préparative, certaines fractions se montrent très performantes contre les parasites.
https://tel.archives-ouvertes.fr/tel-00636165

tel-00636165
https://tel.archives-ouvertes.fr/tel-00636165
https://tel.archives-ouvertes.fr/tel-00636165/document
https://tel.archives-ouvertes.fr/tel-00636165/file/thesePharma_Odonne.PDF

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Isotopes have been widely used for source identification since the early twentieth century. Recent advances in analytical techniques have increased the precision and the accuracy of isotope analysis. As a result, the use of isotopes has spread to several fields (e.g., ecology, food chemistry, archaeology, environmental health and pollution, and forensic sciences). This review examines the principal uses of stable-isotope analyses for tracing origins or sources, along with statistical methods employed for data interpretation, in recent papers (2007―09) dealing essentially with food authentication, ecology, environmental pollution and other applications, including geology, police forensics, hydrology and archaeometry. The main elements analyzed were H, C, N, O, S, Sr and Pb. For isotope-data interpretation, statistical methods appear to depend essentially on the field, the objectives of the study and the number of parameters. They were not often stated explicitly because the studies were exploratory and aimed primarily at assessing the relevance of the analytical techniques used to identify sources. We critically discuss the adequacy of these methods.
ISSN: 0165-9936

hal-00687383
https://hal.archives-ouvertes.fr/hal-00687383

Éditeur(s) : HAL CCSD
Résumé : International audience
In the context of climate change, this study presents the ability of major/trace elements together with strontiumisotopes to trace back water paths at small scale and to deconvolve the geochemical signal of a small watershedsubject to intense flash floods episodes (Peyne, Hérault, France). Two small sub-basins draining distinct lithologiesin their heads (Plio-Villafranchian conglomerate versus Triassic gypsum-rich marls and dolomites) and the sameMiocene lithology downstream are investigated.Major elements and Ca/Na vs. Mg/Na ratios classically applied at large scale to distinguish carbonate from silicateweathering, allow here discriminating the three main lithologies from the two sub-basins. Trace elements Rband Sr coupled to calcium, also allow this lithological discrimination but in addition the Ca/Rb vs. Sr/Rb tracersappear to be much more discriminant for the various hydrological conditions. Thus, in combination with detailedlithological descriptions, they allow identifying the different facies that imprint the water signature through water-rock interaction according to the hydrological conditions.Strontium isotopes and Rb/Sr ratio, discriminate more precisely the drained lithologies of the 2 sub-basins. Firstly,the 87Sr/86Sr ratios allow identifying the nature of the lithologies and their main component(s) contributing to theSr budget in water and thus imprint the isotopic signature. Secondly, Sr isotopes evidenced two distinct Miocenefacies: the detritric faction (sandy marls), and the marine carbonates.The geochemical signatures of the brook samples draining both compartments were compared to the signatureof the Peyne River outlet just before the confluence into the Hérault River. It appears that the signature of thePeyne River, integrating all the water draining the basin, is relatively stable whatever the hydrological conditionsand mainly marked by the Miocene formations. Sr isotopes further highlight that this signature seems to resultfrom the mixing of both Miocene facies present in the lower part of the Peyne watershed, i.e. the sandy marls andthe carbonates. The typical signatures of the Plio-Villafanchian conglomerates and Triassic gypsiferous marls anddolomites of the headwaters of each sub-basin are completely hidden by the Miocene signatures. This should berelated to the large drainage area of the Miocene compared to other lithologies, despite the high solubility of thegypsum formations releasing large quantities of dissolved elements in solution.Understanding water paths at small scale is even more efficient when the geochemical approach is coupled with adetailed geological description. Indeed, the geochemical tracers are extremely dependent on the facies sequences(morphology) and of the soil nature (mineralogical composition), this is particularly sensitive at small scale.In the context of climate change increasing the intensity of rain events in the Mediterranean region, and resultingin catastrophic floods events (flash floods), tracing the origin of water contributing to the runoff is of primaryimportance and this must be investigated at small scale. Geochemical and isotopic fingerprinting thus constituteexcellent tools which can help to define the area of interest to be monitored in the framework of flood forecast andwarning networks
EGU General Assembly 2015
Vienne, Austria

hal-01118622
https://hal-brgm.archives-ouvertes.fr/hal-01118622