Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Fromthe Proterozoic to the Quaternary, the evolution of the Earthwas characterised by recurrent periods of glaciation.However, the margins of many ancient ice-sheets are poorly defined on palaeogeographic reconstructions.The extent and outlines of ancient ice sheets can be better understood through careful documentation ofsediments deposited at the ice-sheet margin. An outstanding example is provided herein based on an end-Ordovician archive in Libya (Tihemboka area, Murzuq Basin). The four sets of structures include: i) subglacialglaciotectonic structures and soft sediment deformations from flowing glacier ice, such as intraformational glacialstriae, intraformational deformation (shear planes, sheath folds), normal microfaults, and large-scaleglaciotectonic folds-and-thrusts; (ii) structures resulting from overpressured subglacial (meltwater) flowssuch as clastic dykes and tunnel valleys; (iii) proglacial depositional structures and facies related to highmagnitudemeltwater floods such as sandstone intraclasts, large-scale bedforms resulting from supercriticalflows, climbing-dune cross-stratification and kettle holes; and (iv) deformation structures resulting from freefloating and nonglacier ice such as ice-keel scours and ice-crystal marks. Such a set of structures points to anice-marginal (essentially continental) depositional setting, and provides an excellent suite of criteria to identifymargins of ancient ice sheets in the stratigraphic record. At a regional scale, a reconstruction through time andspace of the related depositional wedge is proposed. This corresponded to a seismic-scale (N120 m in thickness,40 km in length) ice-marginal wedge in front of an essentially warm-based ice-sheet inducing concomitantlarge-scale glaciotectonic deformation, glacial basin and tunnel valley downcuttings. The related ice-front wasassociated with high-energy meltwater flows feeding a network of deeply incised proglacial channels downstreamand, beyond them, a fluvioglacial deltaic system. Shallow ice-marginal permafrost most likely affectedthe depositional wedge. At a larger scale, the Tihemboka ice-marginal wedge is interpreted as related to a stillstandperiod over the Gondwana platform, developed over an estimated interval of a few thousands of years.Based on these data, the conditions that arose in a particularly favourable context for the development, the preservationand the identification of ice-marginal wedges in the geological record are reviewed. Significantmeltwater-derived sediment deposition and aggradation in an accommodation space resulting either frompreglacial inheritance, glacial downcuttings and/or glacio-isostatic lithospheric flexure, or active tectonic subsidence(>1 Myr) are required for their formation and subsequent preservation.
ISSN: 0012-8252

insu-01184739
https://hal-insu.archives-ouvertes.fr/insu-01184739
DOI : 10.1016/j.earscirev.2015.06.006

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The N-S Languedoc volcanic province between the French Massif Central and the Mediterranean Sea is characterized by sporadic scattered low volume (similar to 2 km(3)) and geochemically homogeneous alkali basaltic activity spanning from 161 to 05 Ma The existence of magmatic activity of such a long duration within such a small area (similar to 140 km long and similar to 60 km wide) in spite of the extensive shift to the East of the European plate (about 2500 km during the last 160 Ma) is problematic Trace-element abundances in lavas suggest low degrees of melting (1-5%) in the spinet-garnet transition zone of an enriched Iherzolitic source The lavas display rather large ranges in Sr isotopic ratios (0 70307-0 70436) The Nd-143/Nd-144 ratio variations are smaller (0 51268-0 51300) and these of Pb-206/Pb-204 Pb-208/Pb-204 and Pb-207/Pb-204 are 18 745-19 515 38 53239 228 and 15 567-15 680 respectively The Languedoc lithospheric mantle as sampled by xenoliths is globally similar to the Pyrenees lithosphere The xenoliths show also rather large Sr Nd and Pb isotopic variations (Sr-87/Sr-86 0 70287-0 70578 Nd-143/Nd-144 0 51256-0 51414 Pb-208/Pb-204 37772-39 041 Pb-206/Pb-204 17 901-19 353) except for Pb-207/Pb-204 (15 570-15 620) The Pb-206/Pb-204 and La/Sm ratios are positively correlated both in xenoliths and lavas The increase of the Pb-206/Pb-204 (which could be interpreted as participation of the European Asthenospheric Reservoir EAR) is probably related to volatile-rich (carbonated?) fluid percolation This is corroborated by LILE and HFSE patterns observed in several xenoliths Therefore our data on lavas and xenoliths suggest a lithospheric origin for this long lived magmatism We propose (1) that the role of the asthenosphere in the Languedoc volcanism was restricted to volatile-rich fluid supplying and (2) that the fluid injection within the lithosphere may be related to the arrival of the Central Atlantic Plume head beneath Western Europe about 70 Ma ago In this model the isotopic signature of the oldest lavas (>70 Ma) would be that of the mantle lithosphere inherited from Hercynian processes The signatures of the subsequent lavas would be driven by the metasomatic component stored within the lithosphere and preferentially mobilized during incipient melting This metasomatised lower lithosphere was close to its solidus and small changes in P (or T) triggered incipient melting leading to basaltic volcanism Successive local re adjustments of the lithospheric blocks which accompanied the Meso-Cenozoic evolution of the Thetys Ligurian margin towards the present Mediterranean margin are the probable cause of these changes and so the sporadic volcanic activity in Languedoc is unrelated to deep asthenospheric processes
ISSN: 0024-4937

hal-00558884
https://hal.archives-ouvertes.fr/hal-00558884
DOI : 10.1016/j.lithos.2010.04.009

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
New U–Pb monazite, zircon, and xenotime ages date the Late Carboniferous crystallization of the anatectic Vialais granite in the Montagne Noire Axial Zone and the high-temperature deformation and metamorphism of the augen gneiss (Ordovician granite protolith) from which the granite was likely derived. The U–Pb monazite ages obtained from the augen gneiss (308 ± 3 Ma), late kinematic Vialais granite (303 ± 4 Ma), and post-kinematic leucogranite (298 ± 2 Ma), bracket the high-temperature deformation and metamorphism at ~ 310–300 Ma, clearly postdating regional contraction and nappe emplacement (> 320 Ma). The planar–linear and locally linear fabrics in the augen gneiss outline a regional-scale double dome structure (Caroux and Espinouse sub-domes) containing smaller (km-scale) upright folds. Compared to the Caroux sub-dome, the larger, migmatitic Espinouse sub-dome contains abundant leucosome, leucogranite bodies and late-kinematic intrusions (Vialais granite). The Vialais granite displays a weak magmatic foliation that defines the main layering of the Espinouse migmatite. Ellipsoidal quartz–sillimanite nodules concentrated above the roof of the granite recorded an increment of strain (vertical shortening, E–NE elongation) during granite emplacement and crystallization, consistent with the extension event that exhumed the domes. These new geochronological and structural data suggest that the Montagne Noire double dome formed in a pull-apart structure within a dextral strike–slip system. Upright folding in the sub-domes has been traditionally assigned to a regional contraction event; alternatively, we propose that local contraction is associated with the convergence of low-viscosity crust beneath the upper crust pull-apart. Dynamic models of extension of hot crust indicate that contraction at depth is generated by flow of low-viscosity orogenic crust converging and rising to fill the gap created by upper crust extension. This interpretation solves the long-standing problem of apparent coeval contraction and extension in the Montagne Noire double dome and establishes migmatite dome emplacement in strike–slip corridors as a style of late Variscan tectonics.
ISSN: 0040-1951

insu-01112009
https://hal-insu.archives-ouvertes.fr/insu-01112009
DOI : 10.1016/j.tecto.2014.12.002

Éditeur(s) : HAL CCSD Seoul National University
Résumé : http://www.episodes.org/backissues/302/abstract2.htm
International audience
The Trans-North China Belt (TNCB) is a Paleoproterozoic collisional orogen (ca. 1.9-1.8 Ga) responsible for the amalgamation of the North China Craton. Detail field works in Lüliangshan, Hengshan, Wutaishan and Fuping massifs where the belt is well exposed, allow us to draw new tectonic map and crustal-scale cross sections. The available petrologic, radiometric, geochronologic data are integrated in a geodynamic evolution scheme for this orogen. The Low Grade Mafic Unit (LGMU) is interpreted as an ophiolitic nappe rooted in a suture zone located in the western part of the Lüliangshan. This ophiolitic nappe overthrusts to the SE upon the Orthogneiss-Volcanites Unit (OVU) that consists of a bimodal volcanicsedimentary series metamorphosed under amphibolite facies conditions intruded by calcalkaline orthogneiss. The OVU is a composite Neoarchean-Paleoproterozoic magmatic arc developed during two stages (ca. 2500 and 2100 Ma) upon a continental basement corresponding to the western extension of the Neoarchean Fuping massif. The OVU overthrusts to the SE the Fuping massif along the Longquanguan shear zone. This stack of nappe, coeval with an amphibolite facies metamorphism, is dated at ca 1880 Ma. Subsequently, the metamorphic series experienced a widespread migmatization at 1850 Ma and was intruded by post-orogenic plutons dated at 1800 Ma. The weakly to unmetamorphosed Hutuo Supergroup unconformably overlies the metamorphosed and ductilely deformed units (OVU and LGMU), but it is also involved in a second tectonic phase developed in subsurface conditions. These structural features lead us to question the ca 2090 Ma age attributed to the Hutuo supergroup. Moreover, in the Fuping massif, several structural and magmatic lines of evidence argue for an earlier orogenic event at ca 2100 Ma that we relate to an older west-directed subduction below the Fuping Block. The Taihangshan Fault might be the location of a possible suture zone between the Fuping Block and an eastern one. A geodynamic model, at variance with previous ones, is proposed to account for the formation of the TNCB. In this scheme, three Archean continents, namely from West to East, the Ordos, Fuping and Eastern Blocks are separated by the Lüliang and Taihang Oceans. The closure of the Taihang Ocean at ca 2100 Ma by westward subduction below the Fuping Block accounts for the arc magmatism and the 2100 Ma orogeny. The second collision at 1900-1880 Ma between the Fuping and Ordos blocks is responsible for the main structural, metamorphic and magmatic features of the Trans-North China Belt.
ISSN: 0705-3797

insu-00152972
https://hal-insu.archives-ouvertes.fr/insu-00152972
https://hal-insu.archives-ouvertes.fr/insu-00152972/document
https://hal-insu.archives-ouvertes.fr/insu-00152972/file/Episodes_TNCB_Faure_et_al.pdf

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
BACKGROUND: Evidence of human sexual transmission during Zika virus emergence is a matter of concern, particularly in procreation, but to date, kinetics of seminal shedding and the effects of infection on human reproductive function have not been described. To investigate the effects of Zika virus infection on semen and clearance of Zika virus from semen and body fluids, we aimed to study a cohort of Zika virus-infected men. METHODS: This prospective observational study recruited men presenting with acute Zika virus infection at Pointe-à-Pitre University Hospital in Guadeloupe, French Caribbean, where a Zika virus outbreak occurred between April and November, 2016. Blood, urine, and semen were collected at days 7, 11, 20, 30, 60, 90, and 120 after symptom onset, and semen characteristics, such as total sperm count, sperm motility, vitality, and morphology, and reproductive hormone concentrations, such as testosterone, inhibin, follicle-stimulating hormone, and luteinising hormone, were assessed. At days 7, 11, and 20, semen was processed to isolate motile spermatozoa. Zika virus RNA was detected by RT-PCR using whole blood, serum, urine, seminal plasma, semen cells, and motile spermatozoa fractions. Zika virus was isolated from different sperm fractions on Vero E6 cultures. FINDINGS: 15 male volunteers (mean age 35 years [SD 5; range 25-44) with acute Zika virus infection and positive Zika virus RNA detection in blood or urine were enrolled. Total sperm count was decreased from median 119 × 10(6) spermatozoa (IQR 22-234) at day 7 to 45·2 × 10(6) (16·5-89·6) at day 30 and 70 × 10(6) (28·5-81·4) at day 60, respectively, after Zika virus infection. Inhibin values increased from 93·5 pg/mL (IQR 55-162) at day 7 to 150 pg/mL (78-209) at day 120 when total sperm count recovered. In motile spermatozoa obtained after density gradient separation, Zika virus RNA was found in three of 14 patients at day 7, four of 15 at day 11, and four of 15 at day 20, and replication-competent virus was found in the tested patient. Seminal shedding kinetics seemed heterogeneous among patients. Whole blood was the fluid most frequently positive for Zika virus RNA (62 of 92 samples) and three patients remained positive at day 120. INTERPRETATION: Semen alterations early after acute Zika virus infection might affect fertility and could be explained by virus effects on the testis and epididymis. Frequency of shedding and high viral load in semen, together with the presence of replicative virus in a motile spermatozoa fraction, can lead to Zika virus transmission during sexual contact and assisted reproduction procedures. Whole blood seems to be the best specimen for Zika virus RNA detection, diagnosis, and follow-up. FUNDING: Agence de la Biomédecine/Agence Régionale de Santé de la Guadeloupe/Inserm-REACTing.
ISSN: 0140-6736

hal-01647078
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01647078
DOI : 10.1016/S1473-3099(17)30444-9
PUBMED : 28838639

Résumé : Les territoires amérindiens couvrent de vastes étendues de forêts tropicales et possèdent une forte valeur sociale et environnementale, soumis à des contraintes et opportunités variées, ils sont de nos jours le siège de nombreuses transformations territoriales. Ces transformations sont complexes et multiformes. Elles impliquent l’adoption de nouveaux modes de productions et de consommation, le réajustement des formes d’organisation sociale et des dynamiques de réaffirmation identitaireet territoriale. Or les liens entre tous ces processus sont encore mal compris et rendent délicate le compréhension des dynamiques d’adaptation des systèmes amérindiens de gestion des ressources communes.Cette thèse s’intéresse particulièrement aux dynamiques territoriales des amérindiens wayapi et teko de la commune de Camopi en Guyane française. Elle intègre des données sur l’occupation de sol obtenues par télédétection, des données socio-économiques et productives à l’échelle des ménages et des données qualitatives sur les processus identitaires, les réseaux de parente, les politiques de conservation et la gouvernance du territoire. Elle montre que malgré la sédentarisation de l’habitat autour des bourgs locaux, la croissance des revenus monétaires issus des emplois salariés et des aides sociales, combinées avec le maintien des réseaux de parente et d’entraide, permet une redynamisation des systèmes de mobilité et une diversification des territoires amérindiens. De plus, les politiques environnementales mises en place sur le territoire impliquent des processus de territorialisation et de revendication identitaires et motivent la construction collective d’un projet de développement local endogène. Une approche comparative avec la situation des amérindiens wayapi vivant au Brésil et évoluant dans un contexte socio-économique, institutionnel et environnemental bien différent montre des dynamiques similaires. Les amérindiens de ces deux pays adoptent des systèmes d’exploitation du territoire multi-locaux, leur permettant d’étendre leur occupation du territoire et s’inscrivant dans une dynamique de réaffirmation identitaire et territoriale. Ils articulent ainsi les espaces de la forêt et des bourgs. Cette forme d’exploitation multi-locale du territoire peut être interprétée comme une nouvelle forme de gouvernance environnementale, qui leur permet de contourner les difficultés et d’affirmer leur souveraineté sur le territoire.
Indigenous territories comprise extensive areas of tropical forest and hold significant social and conservation value. Today, they are subject to various constraints and opportunities and face many territorial transformations. These transformations are complex and multifaceted. They involve the adoption of new production and consumption modes, the medications of forms of social organization and identity and territorial claims. However, the links between these on-going processes are still poorly understood, and make difficult to appreciate the adaptation dynamics of indigenous common natural resources management. This thesis is particularly concerned with the territorial dynamics of the wayapi and teko indigenous people of the municipality of Camopi in French Guyana. It integrates methods that include land use analysis using remotely sensed data, socio-economic and agricultural systems analysis at the household scale, and empirical analysis on the influence of identity claims, kinship networks, and conservation policies. It shows that despite the residential settlement around local towns, the growth of cash income from wage labour and welfare, associated with strong kinship networks, allows the revival of mobility and the diversification of indigenous territorialities. Environment policies implemented on the territory involve processes of identity and territorial claims and motivate the construction of a collective project of endogenous local development. A comparative approach with the situation of the Wayapi people living in Brazil, and evolving in a completely different institutional, socio-economic and environmental context shows similar dynamics. Indigenous people of these two sites adopt “multi-local” land use systems, allowing them to extend their territory occupation and taking part of a broader dynamic of territorial and identity affirmation. They articulate forest and local town environments. This multi-local land use sytem can be interpreted as a new form of environmental governance, which overcomes the difficulties access to natural resources around local towns and ensure their sovereignty over the territory.

http://www.theses.fr/2013AGUY0608/document

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
The CoPanFlu-France cohort of households was set up in 2009 to study the risk factors for infection by the pandemic influenza virus (H1N1pdm) in the French general population. The authors developed an integrative data-driven approach to identify individual, collective and environmental factors associated with the post-seasonal serological H1N1pdm geometric mean titer, and derived a nested case-control analysis to identify risk factors for infection during the first season. This analysis included 1377 subjects (601 households). The GMT for the general population was 47.1 (95% confidence interval (CI): 45.1, 49.2). According to a multivariable analysis, pandemic vaccination, seasonal vaccination in 2009, recent history of influenza-like illness, asthma, chronic obstructive pulmonary disease, social contacts at school and use of public transports by the local population were associated with a higher GMT, whereas history of smoking was associated with a lower GMT. Additionally, young age at inclusion and risk perception of exposure to the virus at work were identified as possible risk factors, whereas presence of an air humidifier in the living room was a possible protective factor. These findings will be interpreted in light of the longitudinal analyses of this ongoing cohort.
ISSN: 1932-6203

Droits : http://creativecommons.org/licenses/by-sa/
hal-01122215
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01122215
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01122215/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01122215/file/journal.pone.0060127.pdf
PUBMED : 23613718

Éditeur(s) : HAL CCSD
Résumé : Indigenous territories comprise extensive areas of tropical forest and hold significant social and conservation value. Today, they are subject to various constraints and opportunities, and face many territorial transformations. These transformations are complex and multifaceted. They involve the adoption of new production and consumption modes, the modification of forms of social organisation and identity and territorial claims. However, the links between these on-going processes are still poorly understood, and make difficult to appreciate the adaptation dynamics of indigenous common natural resources management. This thesis is particularly concerned with the territorial dynamics of the Wayãpi and Teko indigenous people of the municipality of Camopi in French Guiana. It integrates methods that include land use analysis using remotely sensed data, socio-economic and agricultural systems analysis at the household scale, and empirical analysis on the influence of identity claims, kinship networks, and conservation policies. It shows that despite the residential settlement around local towns, the growth of cash income from wage labour and welfare, associated with strong kinship networks, allows the revival of mobility and the diversification of indigenous territorialities. Environmental policies implemented on the territory involve processes of identity and territorial claims and motivate the construction of a collective project of endogenous local development. A comparative approach with the situation of the wayãpi people living in Brazil and evolving in a completely different institutional, socio-economic and environmental context shows similar dynamics. Indigenous peoples of these two sites adopt "multi-local" land use systems, allowing them to extend their territory occupation and taking part of a broader dynamic of territorial and identity affirmation. They articulate forest and local town environments. This multi-local land use system can be interpreted as a new form of environmental governance, which overcomes the access difficulties to natural resources around local towns and ensures their sovereignty over the territory.
Les territoires amérindiens couvrent de vastes étendues de forêts tropicales et possèdent une forte valeur sociale et environnementale. Soumis à des contraintes et opportunités variées, ils sont de nos jours le siège de nombreuses transformations territoriales. Ces transformations sont complexes et multiformes. Elles impliquent l'adoption de nouveaux modes de production et de consommation, le réajustement des formes d'organisation sociale et des dynamiques de réaffirmation identitaire et territoriale. Or les liens entre tous ces processus sont encore mal compris, et rendent délicate la compréhension des dynamiques d'adaptation des systèmes amérindiens de gestion des ressources communes. Cette thèse s'intéresse particulièrement aux dynamiques territoriales des Amérindiens wayãpi et teko de la commune de Camopi en Guyane française. Elle intègre des données sur l'occupation du sol obtenues par télédétection, des données socio-économiques et productives à l'échelle des ménages et des données qualitatives sur les processus identitaires, les réseaux de parenté, les politiques de conservation et la gouvernance du territoire. Elle montre que malgré la sédentarisation de l'habitat autour des bourgs locaux, la croissance des revenus monétaires issus des emplois salariés et des aides sociales, combinée avec le maintien de réseaux de parenté et d'entraide, permet une redynamisation des systèmes de mobilité et une diversification des territorialités amérindiennes. De plus, les politiques environnementales mises en place sur le territoire impliquent des processus de territorialisation et de revendications identitaires et motivent la construction collective d'un projet de développement local endogène. Une approche comparative avec la situation des Amérindiens wayãpi vivant au Brésil et évoluant dans un contexte socio-économique, institutionnel et environnemental bien différent montre des dynamiques similaires. Les Amérindiens de ces deux pays adoptent des systèmes d'exploitation du territoire multi-locaux, leur permettant d'étendre leur occupation du territoire et s'inscrivant dans une dynamique de réaffirmation identitaire et territoriale. Ils articulent ainsi les espaces de la forêt et des bourgs. Cette forme d'exploitation multi-locale du territoire peut être interprétée comme une nouvelle forme de gouvernance environnementale, qui leur permet de contourner les difficultés d'accès aux ressources naturelles autour des bourgs et d'affirmer leur souveraineté sur le territoire.
https://tel.archives-ouvertes.fr/tel-00831619

tel-00831619
https://tel.archives-ouvertes.fr/tel-00831619
https://tel.archives-ouvertes.fr/tel-00831619/document
https://tel.archives-ouvertes.fr/tel-00831619/file/These_TRITSCH_mai2013_vf.pdf

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Multiproxy analyses were performed on core MS27PT recovered in hemipelagic sediments deposited on the Nile margin in order to reconstruct Nile River palaeohydrological fluctuations during the last 100,000 years. The strontium and neodymium isotope composition of the terrigenous fraction and the major element distribution reveal large and abrupt changes in source, oscillating between a dominant aeolian Saharan contribution during arid periods and a dominant Nile River contribution during pluvial periods. Iron content shows a strong correlation with strontium and neodymium isotopes. This allows the use of a high-resolution continuous Fe record as a proxy of Blue Nile sediment input over the last 100,000 years. The detailed Fe record, with approximately 10 years resolution during pluvial periods, is consistent with subtropical African records of well-dated lake level fluctuations and thus constitutes a first continuous high resolution record of the East African monsoon regime intensity over Ethiopia.;The detailed Fe record shows the two main known pluvial periods attributed to strengthening of the African monsoon over Ethiopia, the Nabtian period from 14 to 8 ka cal BP and the Saharan period from 98 to 72 ka BR For the first time, the last glacial period (Marine Isotope Stage (MIS) 2,3 and 4) is documented with a continuous record showing large oscillations between high and low East African palaeo-monsoon regimes.;The end of the Nabtian period occurred at 8 ka in core MS27PT, i.e. much earlier than on the East Equatorial African region where it ended around 5.5 ka. We interpret this as evidence that the southward shift of the rain belt occurred 3000 years earlier over the Eastern Ethiopian Highland and propose that the gradual southward migration of the rain belt was associated with highly variable intensity and longer rainy seasons from 8 to 5 ka. During the last glacial period, two wet periods are present around 60-50 ka BP and 38-30 ka BP. These two humid periods are in phase with the rise of atmospheric CH4 concentrations suggesting that wetland tropical African area was one of the sources of the atmospheric CH4 during the MIS 3. During the Last Glacial Maximum and MIS 4, high Saharan aeolian influxes in phase with records of aeolian dust deposited in East Antarctica are documented. This study highlights the importance of reconstructions of monsoon rainfall fluctuation at high temporal resolution to better understand the link between low- and high-latitude climate variability at millennial timescales.
ISSN: 0277-3791

hal-00496481
https://hal.archives-ouvertes.fr/hal-00496481
DOI : 10.1016/j.quascirev.2010.02.006

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
Field study, thermochronology and geochemistry of the east Lungmu Co (LMC) range highlight some of the geological events that shaped western Tibet. The LMC fault zone has long been interpreted as the boundary between the Tianshuihai terrane of Laurasian affinity and the Qiangtang block of Gondwanian affinity. In the LMC range, the Paleozoic series is intruded by the Mangtsa leucogranite whose zircon have a U/Pb age of 116.9 ± 1 Ma and by mafic rocks with U/Pb zircon ages ranging from 116.9 ± 1 to 95.1 ± 1.7 Ma. Geochemistry of the mafic rocks indicates that they have been emplaced in a supra-subduction zone setting, probably the north dipping Nujiang suture zone. 40Ar/39Ar micas ages of the granite indicate that cooling below ~ 350 °C occurred between 105 and 85 Ma. 40Ar/39Ar K-feldspar data suggest a fast cooling event at 60-55 Ma, which we relate to the reactivation of the LMC suture zone as a thrust at the onset of the India-Eurasia collision. The last, and still active, deformation event corresponds to left-lateral strike-slip faulting along the ENE-WSW LMC fault.
ISSN: 1342-937X

hal-00660491
https://hal.archives-ouvertes.fr/hal-00660491
DOI : 10.1016/j.gr.2011.07.026

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Diamond-bearing UHP metamorphic rocks witness for subduction of lithospheric slabs into the mantle and their return to shallow levels. In this study we present U–Pb and trace elements analyses of zircon and rutile inclusions from a diamond-bearing garnet megacryst collected in a mélange unit exposed on the northern margin of Africa (Edough Massif, NE Algeria). Large rutile crystals (up to 300 μm in size) analyzed in situ provide a U–Pb age of interpreted as dating the prograde to peak subduction stage of the mafic protolith. Trace element analyses of minute zircons (≤30 μm) indicate that they formed in equilibrium with the garnet megacryst at a temperature of 740–810 °C, most likely during HP retrograde metamorphism. U–Pb analyses provide a significantly younger age of attributed to exhumation of the UHP units. This study allows bracketing the age of UHP metamorphism in the Western Mediterranean Orogen to the Oligocene/early Miocene, thus unambiguously relating UHP metamorphism to the Alpine history. Exhumation of these UHP units is coeval with the counterclockwise rotation of the Corsica–Sardinia block and most likely resulted from subduction rollback that was driven by slab pull.
ISSN: 0012-821X

hal-01622789
https://hal.archives-ouvertes.fr/hal-01622789
DOI : 10.1016/j.epsl.2017.06.043

Éditeur(s) : HAL CCSD Geological Society of America
Résumé : International audience
On the New Jersey shelf (offshore North America), the presence of pore water fresher than seawater is known from a series of boreholes completed during the 1970s and 1980s. To account for this fresh water, a fi rst hypothesis involves possible present-day active dynamic connections with onshore aquifers, while a second involves meteoritic and/or sub- ice-sheet waters during periods of lowered sea level. Expedition 313 drilled three boreholes on the middle shelf, offering a unique opportunity for the internal structure of the siliciclastic system to be accessed, at scales ranging from the depositional matrix to the continental margin. This enables the stratigraphic architecture to be correlated with the spatial distribution and salinity of saturating fl uids. Expedition 313 revealed both very low salinities (<3 g/L) at depths exceeding 400 m below the seafl oor and evidence for a multilayered reservoir organization, with freshand/ or brackish-water intervals alternating vertically with salty intervals. In this study we present a revised distribution of the salinity beneath the middle shelf. Our observations suggest that the processes controlling salinity are strongly infl uenced by lithology, porosity, and permeability. Saltier pore waters generally occur in coarse-grained intervals and fresher pore waters occur in fi ne-grained intervals. The transition from fresher to saltier intervals is often marked by cemented horizons that probably act as permeability barriers. In the lowermost parts of two holes, the salinity varies independently of lithology, suggesting different mechanisms and/or sources of salinity. We present an interpretation of the sedimentary facies distribution, derived from core, logs, and seismic profi le analyses, that is used to discuss the marginscale two-dimensional reservoir geometry and permeability distribution. These proposed geometries are of primary importance when considering the possible pathways and emplacement mechanisms for the fresh and salty water below the New Jersey shelf.
EISSN: 1553-040X

insu-00858241
https://hal-insu.archives-ouvertes.fr/insu-00858241
DOI : 10.1130/GES00855.1

Éditeur(s) : HAL CCSD Geological Society of America
Résumé : International audience
Fluid-rock interactions can control earthquake nucleation and the evolution of earthquake sequences. Experimental studies of fault frictional properties in the presence of fluid can provide unique insights into these interactions. We report the first results from experiments performed on cohesive silicate-bearing rocks (microgabbro) in the presence of pressurized pore fluids (H2O, drained conditions) at realistic seismic deformation conditions. The experimental data are compared with those recently obtained from carbonate-bearing rocks (Carrara marble). Contrary to theoretical arguments, and consistent with the interpretation of some field observations, we show that frictional melting of a microgabbro develops in the presence of water. In microgabbro, the initial weakening mechanism (flash melting of the asperities) is delayed in the presence of water; conversely, in calcite marble the weakening mechanism (brittle failure of the asperities) is favored. This opposite behavior highlights the importance of host-rock composition in controlling dynamic (frictional) weakening in the presence of water: cohesive carbonate-bearing rocks are more prone to slip in the presence of water, whereas the presence of water might delay or inhibit the rupture nucleation and propagation in cohesive silicate-bearing rocks.
ISSN: 0091-7613

hal-01054327
https://hal.archives-ouvertes.fr/hal-01054327
DOI : 10.1130/G34916.1

Résumé : Ce travail analyse le dancehall, dernière forme en date de la musique jamaïcaine, à travers les questions de violence et de sexualité. Cette musique rencontre des difficultés sur le plan local et international non seulement à cause des thématiques abordées mais aussi par la manière dont elles sont traitées. Ainsi, le traitement de la violence à travers le gun talk, ces textes faisant l’apologie des armes à feu, entraîne des critiques, on leur reproche d’être des incitations à la violence physique, psychologique, au désordre social et on juge leur influence négative. Par ailleurs, l’approche très explicite et très crue de la sexualité entraîne également des critiques du fait de la teneur misogyne et homophobe de certaines chansons.Par conséquent, cette étude du dancehall explique les raisons pour lesquelles le contexte particulier de la Jamaïque a conduit à ce genre de propos. Puis, elle démontre que les textes incriminés pour homophobie ou misogynie renferment une codification de la sexualité qui va au-delà de l’orientation sexuelle et de l’opposition hétérosexualité/homosexualité, pour ériger un modèle valorisant et valorisé en termes de pratiques sexuelles (le coït pénis/vagin). Pour répondre à ces questions, cette analyse s’appuie sur une série d’outils offrant une vision cohérente de cette musique : les travaux précédents sur le dancehall, les traductions d’un large éventail de chansons, l’utilisation de l’Internet qui permet de suivre les derniers déroulements de ce phénomène culturel en constante évolution et enfin les entretiens et les enquêtes menés sur le terrain.
Completely different to play a part in the social unrest that this country is facing. The second part of the thesis focuses on the issues of violence and sexuality in dancehall music. It shows how politics and religion have a strong influence on the population and offer some legitimacy to the lyrics which lead to the controversies surrounding dancehall music. On the one hand, religion is the cornerstone of this society (although Jamaicans have integrated some principles and do not pay much attention to others) and determines what should be endorsed or rejected. On the other hand, the politicians apply some sort of physical and psychological violence to maintain their leading position. In addition, these politicians rely on the contempt for homosexuality to create cohesion within a society that is deeply characterized by divisions and tensions of all kinds. In the Jamaican context that is deeply influenced by patriarchal values, the individuals of the lower social strata (especially males) who experience difficulties to obtain a valorizing social status can turn to violence and criminal activities, and will hang to heterosexuality and “moral” sexual practices as vehicles to restored self-esteem (this vision of sexuality is one of the only valorizing aspects of masculinity that any individual can rely on regardless of their social status). Consequently, these sexual archetypes are expressed through the lyrics of dancehall music and are promoted by the artists of dancehall, self-proclaimed spokesperson for the Jamaican population. The third part addresses the issue of the perception of dancehall music on the international level through the issue of sexuality and homosexuality. This part shows that even though the language used by the artists can be hardly understood, some lyrics leave the listeners with different way of interpreting the message, especially when it comes to threatening some people physically or psychologically on the ground of sexual orientations and practices. These songs which express strong criticism towards some individuals have triggered vehement reactions from sexual minority groups. Different campaigns on the international level have forced the artists to tone down their lyrics. These campaigns show how the music is also utilized by these gay groups to fight against discrimination. Because of or thanks to the media attention that Jamaican music enjoys, the homosexuals are able to expose to the public opinion the physical and psychological violence they are experiencing in Jamaica. In addition, the close geographic, cultural and economic relationship between Jamaica and the USA shows, on the one hand, how homosexuality is perceived on the island as an imposed foreign value and on the other hand, how this Caribbean country is labeled as a homophobic nation. And finally, the influence of Jamaica on the international level allows us to analyze dancehall music in the French Caribbean islands. This chapter shows how these local artists can use the Jamaican codes and adapt them to their own reality when they correspond with the values of their own society.

http://www.theses.fr/2013AGUY0728/document

Éditeur(s) : HAL CCSD Springer
Résumé : International audience
Thiswork examines the relevance of the inclusion of ground-based gravity data in the calibration process of a global rainfall-discharge reservoir model. The analysis is performed for the Durzon karst system (Larzac, France). The first part of the study focuses on the hydrological interpretation of the ground-based gravity measurements. The second part of the study investigates further the information content of the gravity data with respect to water storage dynamics modelling.The gravity-derived information is found unable to either reduce equifinality of the single-objective, dischargebased model calibration process or enhance model performance through assimilation.
ISSN: 1866-6280

hal-00812624
https://hal-brgm.archives-ouvertes.fr/hal-00812624
DOI : 10.1007/s12665-012-1856-z

Éditeur(s) : HAL CCSD American Chemical Society
Résumé : International audience
Four bicyclic and three pentacyclic guanidine alkaloids (1–7) were isolated from a French Polynesian Monanchora n. sp. sponge, along with the known alkaloids monalidine A (8), enantiomers 9–11 of known natural product crambescins, and the known crambescidins 12–15. Structures were assigned by spectroscopic data interpretation. The relative and absolute configurations of the alkaloids were established by analysis of 1H NMR and NOESY spectra and by circular dichroism analysis. The new norcrambescidic acid (7) corresponds to interesting biosynthetic variation within the pentacyclic core. All compounds exhibited antiproliferative and cytotoxic efficacy against KB, HCT116, HL60, MRC5, and B16F10 cancer cells, with IC50 values ranging from 4 nM to 10 μM.
ISSN: 0163-3864

hal-01584556
https://hal.archives-ouvertes.fr/hal-01584556
DOI : 10.1021/acs.jnatprod.6b00168

Éditeur(s) : HAL CCSD American Geophysical Union
Résumé : International audience
We investigate flexural geometry and rheology of the India plate beneath the eastern Himalaya from a new gravity data set acquired in Bhutan. Compared to the well‒studied Nepal Himalaya, the obtained Bouguer anomaly profiles across the range show shorter wavelength flexure of the lithosphere with a narrower and shallower foreland basin. This new data set and seismic Moho constraints are interpreted together in terms of lithospheric flexure using a 2‒D thermomechanical model. Our results suggest that the strongest layer of the continental lithosphere beneath Bhutan is the upper mantle, as it is beneath Nepal. The observed west‒to‒east decrease in flexural wavelength is associated with weakening mantle rheology. The simulations show that this decrease can be related to ductile mantle behavior: either hydrated wet dunite or dry and hot olivine rheology. Both models display decoupled lithospheric layers leading to an eastward decrease of flexural rigidity from ∼1024 to ∼5*1022 N m in Nepal and Bhutan, respectively.
ISSN: 0094-8276

hal-00903564
https://hal.archives-ouvertes.fr/hal-00903564
DOI : 10.1002/grl.50793

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
Projections of climate change impacts on coral reefs produced at the coarse resolution (~1°) of Global Climate Models (GCMs) have informed debate but have not helped target local management actions. Here, projections of the onset of annual coral bleaching conditions in the Caribbean under Representative Concentration Pathway (RCP) 8.5 are produced using an ensemble of 33 Coupled Model Intercomparison Project phase-5 models and via dynamical and statistical downscaling. A high-resolution (~11 km) regional ocean model (MOM4.1) is used for the dynamical downscaling. For statistical downscaling, sea surface temperature (SST) means and annual cycles in all the GCMs are replaced with observed data from the ~4-km NOAA Pathfinder SST dataset. Spatial patterns in all three projections are broadly similar ; the average year for the onset of annual severe bleaching is 2040–2043 for all projections. However, downscaled projections show many locations where the onset of annual severe bleaching (ASB) varies 10 or more years within a single GCM grid cell. Managers in locations where this applies (e.g., Florida, Turks and Caicos, Puerto Rico, and the Domini-can Republic, among others) can identify locations that represent relative albeit temporary refugia. Both downscaled projections are different for the Bahamas compared to the GCM projections. The dynamically downscaled projections suggest an earlier onset of ASB linked to projected changes in regional currents, a feature not resolved in GCMs. This result demonstrates the value of dynamical downscaling for this application and means statistically downscaled projections have to be interpreted with caution. However, aside from west of Andros Island, the projections for the two types of downscaling are mostly aligned; projected onset of ASB is within AE10 years for 72% of the reef locations.
ISSN: 1354-1013

Droits : http://creativecommons.org/licenses/by-nc/
hal-01223492
https://hal-univ-perp.archives-ouvertes.fr/hal-01223492
https://hal-univ-perp.archives-ouvertes.fr/hal-01223492/document
https://hal-univ-perp.archives-ouvertes.fr/hal-01223492/file/Hooidonk_et_al-2015-Global_Change_Biology.pdf
DOI : 10.1111/gcb.12901

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : Tangential strains were measured with strain gauges at the surface of xylem and inner bark of saplings of Cryptomeria japonica D. Don. and Fagus silvatica L. during a pressurization test. The test consists in submitting the whole sapling to an artificially imposed hydrostatic pressure of increasing magnitude. The elastic response of the stems was found linear both at the surface of xylem and inner bark. A simple geometric model allows to compute radial strains in each tissue from tangential strain data. Inside inner bark, radial strains are much larger than tangential strains, because tangential strains are restrained by the core of wood. The material compliance of each tissue was computed as the ratio between the radial strain and the pressure that caused it. The material compliance of xylem is much lower than that of inner bark, but, as its thickness is much larger, its contribution to the apparent behavior of the stem is not negligible. Computation of material compliances by this pressurization test provides information about the specific behavior of each tissue in response to hydrostatic pressure. This can be used to estimate and interpret the calibration factor linking the water status of the plant to the apparent strain measured at its surface.
ISSN: 0931-1890

hal-01031900
https://hal.archives-ouvertes.fr/hal-01031900
DOI : 10.1007/s00468-006-0061-7