Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The Cerro del Almirez massif (Nevado–Filábride Complex, Betic Cordillera, SE Spain) is composed of antigorite (Atg-) serpentinite and chlorite (Chl-) harzburgite separated by a thin reaction front formed in a palaeo-subduction setting. These ultramafic rocks preserve unique prograde structures related to the pre- and peak high-pressure event (1.6–1.9 GPa and 680–710 °C). The oldest subduction-related structures are preserved in Atg-serpentinites: a penetrative S1 foliation and associated L1 stretching lineation that formed in a non-coaxial regime with a top-to-the-W sense of shear. This planar–linear fabric is crosscut by olivine ± Ti-clinohumite veins, formed during the prograde breakdown of brucite and pre-metamorphic clinopyroxene, which form a system of veins decimetres long. They record embrittlement processes due to the release of 6 vol.% of H2O associated with brucite dehydration. The growth of prograde olivine and/or tremolite porphyroblasts is syn- to post-kinematic in relation to the S1 foliation. Further reactions at higher temperature related to the complete breakdown of the Atg (i.e. Atg-out) are post-kinematic to S1. Prograde Chl-harzburgite is crosscut by sets of conjugate zones associated with grain-size reduction of olivine grains. These grain-size reduction zones are interpreted as brittle structures generated by hydrofracturing due to overpressure fluids in a compressional setting at low-differential stresses.Structures related to the exhumation process are mainly preserved in the metasedimentary host rock, where an S2/L2 planar–linear fabric developed within a shear zone dominated by a non-coaxial regime with a top-to-the-W sense of movement in a transpressional regime. Peak metamorphic conditions deduced for the schists are similar in pressure (1.3–1.9 GPa) but lower in temperature (560–590 °C) compared to the ultramafic rocks in contact with them, suggesting a major shear zone at the base of the ultramafic massif during D2 deformation in a right-handed transpressional regime.
ISSN: 0040-1951

hal-01172303
https://hal.archives-ouvertes.fr/hal-01172303
DOI : 10.1016/j.tecto.2014.12.022

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
The mantle above a subducting slab is the site of complex interactions between deformation, partial melting, fluid migration and magma transport. To constrain these interactions and their effects on olivine deformation, we analyze microstructures, crystal preferred orientations, and water contents of peridotite xenoliths entrained by andesites of the Avacha volcano, southern Kamchatka arc. These xenoliths are refractory spinel harzburgites that have coarse-grained microstructures with widely spaced subgrain boundaries and sinuous grain boundaries in olivine, consistent with deformation by dislocation creep under low deviatoric stress (< 13 MPa) and with a significant contribution from diffusional processes. Analysis of crystal preferred orientations (CPO) indicates dominant activation of high-temperature, low-stress {0kl}[100] slip systems in olivine and of(100)[001] in orthopyroxene. In most samples, coarse opx crystals, elongated parallel to the lineation, enclose small olivine grains in crystallographic continuity with neighbouring crystals, indicating crystallization of orthopyroxene at the expense of olivine as a result of reactive percolation of Si-rich fluids coeval with the high-temperature deformation. Secondary crystallization of interstitial orthopyroxene led locally to development of opx-rich lenses parallel to the foliation, characterized by a decrease in olivine grain size and dispersion of the olivine CPO without changing the dominant slip systems. Half of the samples also show acicular orthopyroxene aggregates with which is associated a fine-grained matrix composed of rounded strain-free olivine, orthopyroxene, spinel, and rare amphibole crystals. This matrix occurs pervasively along grain boundaries or forms millimeter-scale irregular lenses and anastomosing veinlets that crosscut the coarse crystals and their ductile deformation structures. Both acicular orthopyroxene and the fine-grained matrix are interpreted as resulting from reactive transport of H2O-rich fluids under static conditions, probably in the lithospheric mantle. Infrared analyses show that olivine contains 1-8 center dot 6 ppm by weight of water. These low water contents are similar to those observed in spinel peridotites from other subduction zones and probably record both the low solubility of water in olivine at low pressure and dehydration during exhumation of the xenoliths. Water contents in orthopyroxene are highly variable (25-506 ppm H2O), probably recording spatially heterogeneous interaction with fluids or melts and compositional disequilibrium in the studied samples. Change in the dominant percolation mechanism from porous flow to fracturing suggests cooling, consistent with the low temperatures estimated from pyroxene thermometry (< 800-900 degrees C). The Avacha xenoliths therefore record pervasive deformation of a region of the mantle under asthenospheric conditions, followed by its accretion to the base of the lithosphere, probably as a result of cooling of the mantle wedge. Percolation of Si-rich fluids or hydrous melts is recorded at all stages; this probably enhanced diffusion and lowered deviatoric stresses during ductile deformation, but did not change the dominant slip direction in olivine from [100] to [001].
ISSN: 0022-3530

hal-00456053
https://hal.archives-ouvertes.fr/hal-00456053
DOI : 10.1093/petrology/egp085

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
We provide new insights into the geochemistry of serpentinites from the Alpine orogenic wedge representing a paleo-subduction zone. These serpentinites are derived from similar oceanic protoliths, but they have experienced different metamorphic conditions related to three different structural levels of the paleo-subduction zone ((1) obducted: Chenaillet ophiolite, (2) accretionary wedge: Queyras Schistes lustrés complex and (3) serpentinite channel: Monviso ophiolite). Metamorphism undergone by these three units is well defined, increasing eastward from sub-greenschist to eclogite facies conditions, and allows us to examine trace element behavior from the oceanic ridge environment to subduction. Serpentinites first record moderate trace element enrichment due to seawater interaction resulting in the replacement of olivine and pyroxene by chrysotile and lizardite below 300 °C. In the sediment-dominated accretionary wedge, serpentinites are strongly enriched in fluid-mobile-elements (B, Li, As, Sb, and Cs) and act as a trapping system following the metamorphic gradient (from 300 to 390 °C) up to total replacement of the lizardite/chrysotile assemblage by antigorite. Under higher temperature conditions (T > 390 °C), no enrichment was observed, and some fluid-mobile elements were released (B, Li, Cs, and Sr). Moreover, in the serpentinite channel (T > 460 °C), most of the fluid-mobile elements are absent due to the scarcity of metasediments which prevent geochemical exchange between metasediments and serpentinites. This is also due to the onset of antigorite breakdown and the release of fluid-mobile elements. Thus, we emphasize that the geochemistry of Alpine serpentinites is strongly dependent on (1) the grade of metamorphism and (2) the ability of metasediments to supply fluid-mobile elements. We conclude that serpentinites act as a trap-and-release system for fluid-mobile elements in a subduction context.
ISSN: 0009-2541

hal-00996839
https://hal.archives-ouvertes.fr/hal-00996839
DOI : 10.1016/j.chemgeo.2013.02.008

Éditeur(s) : Elsevier Science Bv
Résumé : On the Mediterranean continental shelves the post-glacial transgressive succession is a complex picture composed by seaward progradations, related to sea level stillstands and/or increased sediment supply to the coasts, and minor flooding surfaces, associated to phases of enhanced rates of sea level rise. Among Late Pleistocene examples, major mid-shelf progradations have been related to the short-term climatic reversal of the Younger Dryas event, a period during which the combination of increased sediment supply from rivers and reduced rates of sea level rise promoted the formation of progradations up to tens-meter thick. While the documentation of coastal and subaqueous progradations recording the Younger Dryas interval are widely reported in the literature, the model of compound progradation within transgressive deposits is not proposed so far. Here we present the documentation of a deltaic system where both delta front sands and related fine-grained subaqueous progradations (prodeltaic to shallow marine) have been preserved. The Paleo Gargano Compound Delta (PGCD) formed offshore the modern Gargano Promontory (southern Adriatic Sea), and is composed by a coastal coarse-grained delta of reduced thickness and a muddy subaqueous clinoform, up to 30 meters thick. The PGCD, probably the first worldwide documentation of a compound delta within the transgressive record, provides the opportunity to investigate the processes controlling the formation of a compound delta system during an overall sea level rise and the factors that allowed its preservation. The finding of the PGCD provides the opportunity of a comparison with modern worldwide compound systems.
Marine Geology (0025-3227) (Elsevier Science Bv), 2015-04 , Vol. 362 , P. 43-59

Droits : 2015 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/00250/36158/34714.pdf
DOI:10.1016/j.margeo.2015.01.010
http://archimer.ifremer.fr/doc/00250/36158/

Éditeur(s) : HAL CCSD
Résumé : Cell signaling contains the whole biological mecanisms allowing the response of a cell to its microenvironnement in an adapted way. Many extremely intertwinned biological reactions are involved in a network that behaves as a complex system. The understanding of cell response requires the development of data acquisition technics and methods to formalize data into models. This point is the main drive of this thesis. We present here two approaches in order to analyse different granularities of cell signaling. In the first one, we used differential model to study the role of a new component of TGF-β canonical pathway. In the second one, we explored the combinatorial complexity of cell signaling, developing a discrete formalism based on guarded transitions. In this approach, we interpreted the whole database Pathway Interaction Database into a single unified model of signal transduction. Simulation and analysis methods, such as reachability and invariance research, have been developed. The interests are presented through an application on cell cycle regulation by cell signaling, and a global analysis on the regulation of genes compared to experimental data.
La signalisation cellulaire regroupe l'ensemble des mécanismes biologiques permettant à une cellule de répondre de façon adaptée à son microenvironnement. Pour ce faire, de nombreuses réactions biologiques entrent en jeux avec un important enchevêtrement, créant ainsi un réseau dont le comportement s'apparente à un système complexe. Le compréhension de la réponse cellulaire à une stimulation passe par le développement conjoint des techniques d'acquisition de données, et des méthodes permettant de formaliser ces données dans un modèle. C'est sur ce dernier point que s'inscrivent les travaux exposés dans cette thèse. Nous présentons ici deux approches visant à répondre à des questions de natures différentes sur la signalisation cellulaire. Dans la première nous utilisons un modèle différentiel pour étudier le rôle d'un nouvel interactant dans la voie canonique du TGF-beta. Dans la seconde nous avons exploré la combinatoire de la signalisation cellulaire en développant un formalisme discret basé sur les transitions gardées. Cette approche regroupe l'interprétation de la base de données Pathway Interaction Database dans un unique modèle dynamique de propagation du signal. Des méthodes de simulations et d'analyses inspirées des techniques de vérification de modèles telles que l'atteignabilité et l'invariance ont été développées. En outre, nous avons étudié la régulation du cycle cellulaire en réponse à la signalisation, ainsi que la régulation des gènes de notre modèle en comparaison avec des données d'expressions.
https://tel.archives-ouvertes.fr/tel-00926487

Droits : info:eu-repo/semantics/OpenAccess
tel-00926487
https://tel.archives-ouvertes.fr/tel-00926487
https://tel.archives-ouvertes.fr/tel-00926487/document
https://tel.archives-ouvertes.fr/tel-00926487/file/AndrieuxThese.pdf

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
During compressive events, deformation in sedimentary basins is mainly accommodated by thrust faulting and related fold growth. Thrust faults are generally rooted in the basement and may act as conduits or barriers for crustal fluid flow. Most of recent studies suggest that fluid flow through such discontinuities is not apparent and depends on the structural levels of the thrust within the fold-and-thrust belt. In order to constrain the paleofluid flow through the Jaca thrust-sheet-top basin (Paleogene southwest-Pyrenean fold-and-thrust belt) this study compares on different thrust faults located at different structural levels. The microstructures in the different fault zones studied are similar and consist of pervasive cleavage, calcite shear veins (SV1), extension veins (EV1) and late dilatation veins (EV3). In order to constrain the nature and the source of fluids involved in fluid-rock interactions within fault zones, a geochemical approach, based on oxygen and carbon stable isotope and trace element compositions of calcite from different vein generations and host rocks was adopted. The results suggest a high complexity in the paleohydrological behaviors of thrust faults providing evidence for a fluid-flow compartmentalization within the basin. Previous studies in the southern part of the Axial Zone (North of the Jaca basin) indicates a circulation of deep metamorphic water, probably derived from the Paleozoic basement, along fault zones related to the major basement Gavarnie thrust. In contrast, in northern part of the Jaca basin, the Monte Perdido thrust fault is affected by a closed hydrological fluid system involving formation water during its activity. The Jaca and Cotiella thrust faults, in turn, both located more to the south in the basin, are characterized by a composite fluid flow system. Indeed, stable isotope and trace element compositions of the first generations of calcite veins suggest a relatively closed paleohydrological system, whereas the late calcite vein generations, which are probably associated with the late tectonic activity of the basin, support a contribution of both meteoric and marine waters. Based on these results, a schematic fluid-flow model is presented. This model allows visualization of three main fluid flow compartments along a N-S transect.
ISSN: 0264-8172

hal-00963606
https://hal.archives-ouvertes.fr/hal-00963606
DOI : 10.1016/j.marpetgeo.2013.09.005

Éditeur(s) : HAL CCSD
Résumé : International audience
This paper presents some considerations about hybrid optimization algorithms useful to optimize real complex system. The given indication could be used by readers to conceive hybrid algorithms. These considerations have been deducted from a concrete application case: the satellites constellations design problem. But each of the advanced techniques proposed in this paper are considered in a more general way to solve other problems. This problem is used to illustrate the techniques along the paper because it is grouping many characteristics (di culties) of contemporary real complex systems: the size and the characteristics of the search space engendered by a combinatorial problem; The irregularity of the criterions; The mathematical and physical heterogeneity of parameters forbids the use of classical algorithms; The evaluation of a solution, which uses a time consuming simulation; A need of accurate values. More details are available in previous papers ([?], [?], [?], [?]). For these reasons, we could learn a lot from this experiment in order to detach hybrid techniques usable for problems having close characteristics. This paper presents the historic leading to the current algorithm, the modeling of the complex system and the sophisticated algorithm proposed to optimize it. Application cases and ways to built signi cant tests of hybrid algorithm are also given.
HPCSE Proceedings
Toulouse, France

hal-00602264
https://hal.archives-ouvertes.fr/hal-00602264

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The Paleozoic-early Mesozoic geology of Tibet was controlled by the rift-drift, seafloor spreading and subduction zone tectonics of a Paleo-Tethyan realm, which evolved between the West Cathaysides (WC) and the East Cimmerides (EC). Different suture zones with ophiolites and ophiolitic mélanges, high-pressure metamorphic belts, magmatic arcs and accretionary prism complexes separating different terranes mark multiple subduction-accretion systems within this Paleo-Tethyan domain, reminiscent of the modern Western Pacific Ocean. Discrete basins separated by different continental blocks and magmatic arcs constituted a complex paleogeography of Paleo-Tethys, and these oceanic strands were closed as a result of subduction with different polarities during the late Paleozoic-Triassic. The Longmu Tso Shuanghu-Changning Menglian Suture zone (LS-CMS) in Tibet represents the main tectonic boundary between the WC and EC that developed in the Devonian. The East Kunlun-A’nyemaqen oceanic slab was subducted northward beneath the East Kunlun terrane in northern Tibet, whereas the Sumdo oceanic slab was subducted northward beneath the South Qiangtang-North Lhasa terrane in southern Tibet. The Longmu Tso Shuanghu-Changning Menglian and Jinshajiang-Ailaoshan-Song Ma ophiolites were developed and emplaced in subduction-accretion systems with opposite polarities (westward and eastward) beneath the North Qiangtang-Qamdo-Simao-Indochina terrane in central Tibet. The Jinshajiang-Ailaoshan-Song Ma oceanic slab was subducted westward beneath the North Qiangtang-Simao-Indochina terrane along the Jinshajiang and Ailaoshan-Song Ma trenches in a trench-ridge-trench triple junction plate configuration. The Emeishan mantle plume produced a large Permian basaltic terrane, developed on the western passive margin of the South China block. The final closure of the Paleo-Tethyan oceanic branches resulted in continental collisions and development of a vast Indosinian orogenic collage in the latest Triassic-Jurassic.
ISSN: 0743-9547

insu-01119604
https://hal-insu.archives-ouvertes.fr/insu-01119604
https://hal-insu.archives-ouvertes.fr/insu-01119604/document
https://hal-insu.archives-ouvertes.fr/insu-01119604/file/Xu-JAES-2015.pdf
DOI : 10.1016/j.jseaes.2015.01.021

Éditeur(s) : HAL CCSD ACM
Résumé : International audience
In 2008 a scientific paper written by Butz and al. investigated Matching in Learning Classifier Systems. Matching represents at least 65% of the computational time when executing a classifier system as reported in Llora and al. We propose to modify that encoding using a fast and accurate matching replacing standard matching algorithm for character-based classifier systems.
Proceedings of the 12th annual conference comp on Genetic and evolutionary computation
Portland, Oregon, United States

hal-00520610
https://hal.archives-ouvertes.fr/hal-00520610
DOI : 10.1145/1830761.1830820

Éditeur(s) : Oxford Univ Press
Résumé : Spatio-seasonal explicit simulation models can predict the impact of spatial management measures on marine fish populations and fishing activities. As fisheries are complex systems, fisheries simulation models are often complex, with many uncertain parameters. Here, the methodology is provided to deliver fishery diagnostics within an uncertainty context using a complex simulation tool. A sensitivity analysis of the model is performed on model outputs using partial least-squares to identify the most sensitive parameters. The impact of several management measures is then simulated using a statistical simulation design taking into account the uncertainty of the selected sensitive parameters. This approach was applied to the Bay of Biscay anchovy stock using the ISIS-Fish (Integration of Spatial Information for Simulation of Fisheries) model to assess the impact of imposing marine protected areas (MPAs) conditionally on parameter uncertainty. The diagnostic appeared to be highly sensitive to the mortality of larvae and juveniles, growth, and reproduction. The uncertainty of the values of these parameters did not permit any of the simulated MPA designs to be proposed. However, according to anchovy catch and biomass, the simulations allowed the low impact of closure duration to be shown and underscored the utility of protecting such key processes as spawning.
Ices Journal Of Marine Science (1054-3139) (Oxford Univ Press), 2010-07 , Vol. 67 , N. 5 , P. 1063-1075

Droits : 2010 ICES/CIEM. Oxford journals
http://archimer.ifremer.fr/doc/00011/12234/9281.pdf
DOI:10.1093/icesjms/fsq002
http://archimer.ifremer.fr/doc/00011/12234/

Éditeur(s) : HAL CCSD
Résumé : International audience
The purpose of our study is to model a geothermal reservoir. When geothermal reservoir are assumed to be composed of pure water, the transfer of mass and energy is classically described by two balance equations: mass balance equation and the energy balance equation. In addition to those equations, fluid velocity ist classically given by the Darcy law while thermodynamic properties, inferred from theoretical or empirical equations of state, are used to close the mathematical system. Once this system is closed, there exist different solutions. The first one is to solve for pressure and temperature with a variable switch to saturation in the two-phase region (e.g. TOUGH2). The second one is to solve for pressure and enthalpy to increase stability of phase transition between single and two-phase states (e.g. Hydrotherm). We adopted the second option and chose te use a splitting method to get rid of the complexity of coupling equations and a finite volume method for the spatial discretization. Selecting object-oriented languages, we developed a multi-language framework, combining Python, Fortran and a C++ implementation of IAPWS (from the freesteam project) including the supercritical equations, in porous media velocity is given by Darcy law and to close the system physical properties are determined by the IAPWS-IF97 thermodynamic formulation. We resolve the equations in pressure and enthalpy instead of pressure and temperature in order to increase stability and to handle easier the passage from a single-phase to a two-phase system. We solve the system by using a splitting method - to get rid of the complexity of coupling equations - and a finite volume method. We offer some freedom to users thanks to the implementation of several methods like explicit or implicit Euler, Runge-Kutta or BDF2 for time solvers or GMRES and BICGSTAB for the linear solver. We can handle several boundary conditions like no-flow - describing a boundary which can not exchange matter with the exterior - or like a mixed-therm condition - a Dirichlet condition to the pressure and a Dirichlet or an outflow condition to the temperature in order to describe a recharge or a discharge zone - ... We're developing a multi-language framework, combining Python, Fortran and the C++ implementation of IAPWS (from the freesteam project). All these languages are object-oriented. We've applied this simulation model to the dogger in Paris, France, to several one-dimensional systems and a two-dimensional one made by Coumou with the CSMP++ platform. The dogger is a reservoir exploited to produce heat by pumping water at 70 and reinjecting it in the reservoir at 40. In the one-dimensional systems we wanted to observe the process of heat transfer from a higher temperature boundary to a smaller one in a high-energy domain. The last simulation shows the natural convection of water in a fault. For every simulation we compared the solutions we found with an other code (TOUGH2 or CSMP++) and they agreed. The next step will be to model the geothermal plant in Guadeloupe, West Indies. It's the only place in France - and in the West Indies so far - producing electricity with the earth power. The temperature can reach up to 1000 and the pressure range is around a few hundreds MPa. In some surface zones we can see two-phase water at atmospheric pressure. In the 1980s Bouillante was a laboratory for France. Since 1995 Bouillante has given 30GWh electricity a year to the Guadeloupeans.
PROCEEDINGS, Thirty-Ninth Workshop on Geothermal Reservoir Engineering
Stanford, United States

Droits : info:eu-repo/semantics/OpenAccess
hal-00944133
https://hal-brgm.archives-ouvertes.fr/hal-00944133
https://hal-brgm.archives-ouvertes.fr/hal-00944133/document
https://hal-brgm.archives-ouvertes.fr/hal-00944133/file/Copol.pdf

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
Upper mantle anisotropy beneath the African IRIS and Geoscope stations is investigated through the measurements of splitting of teleseismic shear waves such as SKS, SKKS and PKS phases. Seismic anisotropy data are interesting on their own as a measure of upper mantle active or frozen deformation beneath a given station, but each station is of potential interest since it can be used to retrieve source-side seismic anisotropy at remote sites if one is able to perform station-side anisotropy correction. We performed systematic investigations of teleseismic shear wave splitting at 15 stations from the IRIS and Geoscope global seismic networks, which are located on both the oceanic and the continental parts of the African plate. Anisotropy is generally well observed at continental stations. The patterns we present generally show much more complexity than the results previously published from smaller data sets. Despite this complexity, the splitting parameters generally appear in several places to contain a signature of the regional geodynamic setting (rift structures, Archaean craton, Pan-African belt), although a deeper source of anisotropy (asthenospheric) may be present. At the oceanic stations, anisotropy measurements are much more difficult to perform because the signal is generally of poor quality. MSEY, in the Seychelles (Indian ocean), is the exception and displays a clear correlation of the azimuth of the fast split shear wave with the trend of the absolute plate motion, as defined by hotspot tracks.
ISSN: 0956-540X

hal-01380389
https://hal.archives-ouvertes.fr/hal-01380389
https://hal.archives-ouvertes.fr/hal-01380389/document
https://hal.archives-ouvertes.fr/hal-01380389/file/Barruol_SKS_afric_GJI2001.pdf
DOI : 10.1046/j.0956-540x.2001.01481.x

Éditeur(s) : HAL CCSD Frontiers Media
Résumé : International audience
Coral reef fisheries support the development of local and national economies and are the basis of important cultural practices and worldviews. Transitioning economies, human development, and environmental stress can harm this livelihood. Here we focus on a transitioning social-ecological system as a case study (Moorea, French Polynesia). We review fishing practices and three decades of effort and landing estimates with the broader goal of informing management. Fishery activities in Moorea are quite challenging to quantify because of the diversity of gears used, the lack of centralized access points or markets, the high participation rates of the population in the fishery, and the overlapping cultural and economic motivations to catch fish. Compounding this challenging diversity, we lack a basic understanding of the complex interplay between the cultural, subsistence, and commercial use of Moorea's reefs. In Moorea, we found an order of magnitude gap between estimates of fishery yield produced by catch monitoring methods (2 t km −2 ∼ year −1) and estimates produced using consumption or participatory socioeconomic consumer surveys (∼24 t km −2 year −1). Several lines of evidence suggest reef resources may be overexploited and stakeholders have a diversity of opinions as to whether trends in the stocks are a cause for concern. The reefs, however, remain ecologically resilient. The relative health of the reef is striking given the socioeconomic context. Moorea has a relatively high population density, a modern economic system linked into global flows of trade and travel, and the fishery has little remaining traditional or customary management. Other islands in the Pacific in similar contexts in Polynesia such as Hawaii, that continue to develop economically, may have small-scale fisheries that increasingly resemble Moorea. Therefore, understanding Moorea's reef fisheries may provide insight into their future.
ISSN: 2296-7745

Droits : http://creativecommons.org/licenses/by/
hal-01325804
https://hal-univ-perp.archives-ouvertes.fr/hal-01325804
https://hal-univ-perp.archives-ouvertes.fr/hal-01325804/document
https://hal-univ-perp.archives-ouvertes.fr/hal-01325804/file/fmars-03-00070.pdf
DOI : 10.3389/fmars.2016.00070

Éditeur(s) : HAL CCSD Universidad de Malaga
Résumé : International audience
The development of information systems follows a long and complex process in which various actors are involved. We report an experiment in which we observe the evolution of the analysis model of an information system through 15 successive versions. We use indicators on the underlying concept lattices built by applying Relational Concept Analysis (RCA) to each version. RCA is an extension of FCA which groups entities based on characteristics they share, including links to other entities. It here helps in analyzing their evolution. From this experience, we establish recommendations to monitor and verify the proper evolution of the analysis process.
CLA'2012: 9th International Conference on Concept Lattices and Applications
Fuengirola (Málaga), Spain

ISBN : 978-84-695-5252-0
lirmm-00743886
http://hal-lirmm.ccsd.cnrs.fr/lirmm-00743886
http://hal-lirmm.ccsd.cnrs.fr/lirmm-00743886/document

Éditeur(s) : HAL CCSD Société géologique de France
Résumé : International audience
In this paper, we provide the first structural map of Les Saintes archipelago (Guadeloupe, Lesser Antilles). The finite strain pattern displays four families of fault systems characterized by their statistical structural orientations: N000-N020, N050-N070, N090-N110 and N130-N140 trending fault systems. Our onshore results thus underline a fault network much more complex than the one depicted by the previous offshore geophysical investigations around Les Saintes archipelago, which show only N120-N150 trending system. According to the available K-Ar dating of the volcanic rocks and the relative chronology of the faults defined in the field, we determine the deformation history in Les Saintes islands since the last 3 Ma. The four highlighted trending fault systems are already active since the Pliocene and are consistent with the present-day extensional tectonics in the Guadeloupe archipelago compatible with the reactiva-tion of inherited structures at the active arc scale. We interpret the tectonic evolution of Les Saintes islands as the result of interplay between subduction of aseismic ridges (Tiburon and Barracuda ridges) and oblique convergence. Furthermore , we recognized an exhumed geothermal paleo-system in Terre-de-Haut island which is a good analogue of the present-day active Bouillante geothermal system. Its duration is estimated at 400 k.y. during the Pliocene.
EISSN: 1777-5817

hal-01625778
https://hal.univ-antilles.fr/hal-01625778
https://hal.univ-antilles.fr/hal-01625778/document
https://hal.univ-antilles.fr/hal-01625778/file/VeratIEtAl_Final.pdf
DOI : 10.2113/gssgfbull.187.1.3

Éditeur(s) : Elsevier Science Bv
Résumé : In tropical shrimp ponds, the increasing of feed input, concomitantly with the stocking shrimp biomass, induces an eutrophication of the ecosystem. Although difficult to maintain, its stability is required to guarantee the success of the culture. A 110-day period of phytoplankton and bacterioplankton stock and dynamics in an earthen pond (1.2 ha area, 1 m depth) was monitored using flow cytometry to provide baseline information on community characteristics and ecosystem instability. Seven autotrophic cell types were identified over the whole sampling period. Prokaryotic cells included Synechococcus sp., a group named UNK which presented an atypical new flow cytometric signature and picoeukaryotes (PEUK). Nanophytoplankton cells were represented by 4 groups: NAN1, NAN2, NAN3 and Cryptophytes. During the first part of the survey, picophytoplankton dominated the phytoplanktonic assemblage. The mean abundance of total cells (up to 8 x 10(6) cells mL(-1)) was among the highest recorded in marine and brackish waters. Bacterial abundance and production ranged from 0.8 to 5.1 x 10(7) cells mL(-1) and from 30 to 110 mu g C L-1 h(-1). A shift from pico to nanophytoplankton abundance was observed for a few days from d 96. During this period, heterotrophic bacteria production and abundance suddenly dropped, implying a change in the functioning of the microbial loop. This shift was concomitant with a significant shrimp mortality outbreak due to Vibrio penaeicida, the etiological agent of a disease known as Syndrome 93, which affects the shrimp industry in New Caledonia. This survey suggests that flow cytometric analysis could be used for the monitoring of aquaculture systems to improve our understanding of the complex phytoplankton and bacterial dynamics of these systems and its potential influence on disease development. (c) 2010 Elsevier B.V. All rights reserved.
Aquaculture (0044-8486) (Elsevier Science Bv), 2010-12 , Vol. 310 , N. 1-2 , P. 112-121

Droits : 2010 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/00029/14068/11312.pdf
DOI:10.1016/j.aquaculture.2010.10.022
http://archimer.ifremer.fr/doc/00029/14068/

Éditeur(s) : HAL CCSD AGU and the Geochemical Society
Résumé : International audience
The transition between the small melt lens observed on top of fast spreading ridge magma chambers and the overlying sheeted dike complex marks the interface between magma and the hydrothermal convective system. It is therefore critical to our understanding of fast spreading ridge accretion processes. We present maps of two areas of the Oman ophiolite where this transition zone is observed as continuous outcrops. Our observations, which include the base of the sheeted dike being crosscut by gabbros, are consistent with episodic dike injections in a steady state model but also suggest that the root of these dikes is commonly erased by vertical movements of the top of the melt lens. Dike assimilation is a possible mechanism for incorporating hydrated phases, which result from hydrothermal alteration, to the melt lens during upward migrations of its upper boundary. Upward migrations are also responsible for a granoblastic overprint of the root of the dikes that is also observed in the stoped diabase xenoliths. This granoblastic overprint attests to reheating of previously hydrothermally altered lithologies which can even trigger hydrous partial melting due to the lowering of the solidus of mafic lithologies by the presence of a water activity. Clinopyroxenes present in these granoblastic lithologies are typically low in Ti and Al content, thus strongly contrasting with corresponding magmatic clinopyroxene. This may attest to the recrystallization of clinopyroxenes after amphiboles under the peculiar conditions present at the root zone of the sheeted dike complex. Downward migrations of the top of the melt lens result in the crystallization of the isotropic gabbros at its roof, which represent the partly fossilized melt lens. Melt lens fossilization eventually occurs when magma supply is stopped or at the melt lens margins where the thermal conditions become cooler. Melt lens migration, recrystallization of hydrothermally altered sheeted dikes during reheating stages, and assimilation processes observed in the Oman ophiolite are consistent with the observations made in IODP Hole 1256D. We propose a general dynamic model in which the melt lens at fast spreading ridges undergoes upward and downward movements as a result of either eruption/replenishment stages or variations in the hydrothermal/magmatic fluxes.
ISSN: 1525-2027

hal-00445249
https://hal.archives-ouvertes.fr/hal-00445249
DOI : 10.1029/2009GC002652

Éditeur(s) : HAL CCSD American Geophysical Union - AGU
Résumé : IODP Expedition 335 "Superfast Spreading Rate Crust 4" returned to ODP Hole 1256D with the intent of deepening this reference penetration of intact ocean crust several hundred meters into cumulate gabbros. This was the fourth cruise of the superfast campaign to understand the formation of oceanic crust accreted at fast spreading ridges, by exploiting the inverse relationship between spreading rate and the depth to low velocity zones seismically imaged at active mid-ocean zones, thought to be magma chambers. Site 1256 is located on 15-million-year-old crust formed at the East Pacific Rise during an episode of superfast ocean spreading (>200 mm/yr full rate). Three earlier cruises to Hole 1256D have drilled through the sediments, lavas and dikes and 100 m into a complex dike-gabbro transition zone. The specific objectives of IODP Expedition 335 were to: (1) test models of magmatic accretion at fast spreading ocean ridges; (2) quantify the vigor of hydrothermal cooling of the lower crust; (3) establish the geological meaning of the seismic Layer 2-3 boundary at Site 1256; and (4) estimate the contribution of lower crustal gabbros to marine magnetic anomalies. It was anticipated that even a shortened IODP Expedition could deepen Hole 1256D a significant distance (300 m) into cumulate gabbros. Operations on IODP Expedition 335 proved challenging from the outset with almost three weeks spent re-opening and securing unstable sections of the Hole. When coring commenced, the destruction of a hard-formation C9 rotary coring bit at the bottom of the hole required further remedial operations to remove junk and huge volumes of accumulated drill cuttings. Hole-cleaning operations using junk baskets returned large samples of a contact-metamorphic aureole between the sheeted dikes and a major heat source below. These large (up to 3.5 kg) irregular samples preserve magmatic, hydrothermal and structural relationships hitherto unseen because of the narrow diameter of drill core and previous poor core recovery. Including the ~60 m-thick zone of granoblastic dikes overlying the uppermost gabbro, the dike-gabbro transition zone at Site 1256 is over 170 m thick, of which more than 100 m are recrystallized granoblastic basalts. This zone records a dynamically evolving thermal boundary layer between the principally hydrothermal domain of the upper crust and a deeper zone of intrusive magmatism. The recovered samples document a sequence of evolving geological conditions and the intimate coupling between temporally and spatially intercalated intrusive, hydrothermal, contact-metamorphic, partial melting and retrogressive processes. Despite the operational challenges, we achieved a minor depth advance to 1522 m, but this was insufficient penetration to complete any of the primary objectives. However, Hole 1256D has been thoroughly cleared of junk and drill cuttings that have hampered operations during this and previous Expeditions. At the end of Expedition 335, we briefly resumed coring and stabilized problematic intervals with cement. Hole 1256D is open to its full depth and ready for further deepening in the near future.
InterRidge News

hal-00688821
https://hal.archives-ouvertes.fr/hal-00688821

Éditeur(s) : Ieee-inst Electrical Electronics Engineers Inc
Résumé : The synthetic aperture radar (SAR) Doppler centroid has been used to estimate the scatter line-of-sight radar velocity. In weak to moderate ocean surface current environment, the SAR Doppler centroid is dominated by the directionality and strength of wave-induced ocean surface displacements. In this paper, we show how this sea state signature can be used to improve surface wind retrieval from SAR. Doppler shifts of C-band radar return signals from the ocean are thoroughly investigated by colocating wind measurements from the ASCAT scatterometer with Doppler centroid anomalies retrieved from Envisat ASAR. An empirical geophysical model function (CDOP) is derived, predicting Doppler shifts at both VV and HH polarization as function of wind speed, radar incidence angle, and wind direction with respect to radar look direction. This function is used into a Bayesian inversion scheme in combination with wind from a priori forecast model and the normalized radar cross section (NRCS). The benefit of Doppler for SAR wind retrieval is shown in complex meteorological situations such as atmospheric fronts or low pressure systems. Using in situ information, validation reveals that this method helps to improve the wind direction retrieval. Uncertainty of the calibration of Doppler shift from Envisat ASAR hampers the inversion scheme in cases where NRCS and model wind are accurate and in close agreement. The method is however very promising with respect of future SAR missions, in particular Sentinel-1, where the Doppler centroid anomaly will be more robustly retrieved.
Ieee Transactions On Geoscience And Remote Sensing (0196-2892) (Ieee-inst Electrical Electronics Engineers Inc), 2012-07 , Vol. 50 , N. 7 , P. 2901-2909

Droits : 2012 IEEE
http://archimer.ifremer.fr/doc/00088/19896/17554.pdf
DOI:10.1109/TGRS.2011.2174998
http://archimer.ifremer.fr/doc/00088/19896/

Éditeur(s) : Elsevier
Résumé : In order to provide reliable scientific advice and support for fisheries management, it is necessary to evaluate the biological and economic sustainability of complex fisheries, such as multi-species multi-fleet fisheries. Existing policy-screening modelling tools are not fully suitable in this purpose due to either an over-simplified description of population dynamics, or due to the lack of consideration of economic aspects. In this paper, we present a package that enables quantitative bioeconomic assessment of management scenarios. Population dynamics is described through spatially- and seasonally-explicit models. Exploitation dynamics is characterized by several fishing activities with specific spatial and seasonal features, and practiced by several kinds of vessels with specific technical characteristics. Exploitation costs and revenues are considered at several levels: the fishing trip, the fishing unit (vessel and crew), and the vessel owner. The model is generic and can be used for different types of fisheries. A database is attached to the software for the storage and updating of information for each fishery. This includes the specification of model dimensions and of the parameters describing populations and exploitation. Several model assumptions regarding either population or exploitation may be adapted to suit a specific fishery. Both policies and corresponding fishers' response may be interactively specified through JAVA (TM) scripts. This version of ISIS-Fish allows for the calculation of biological and economic consequences of a range of policies, including conventional ones like catch and effort controls, and alternative policies such as marine protected areas. To facilitate policy-screening in a high-dimension parameter space, the software includes features, like interfaces for sensitivity analysis and simulation queues. (C) 2009 Elsevier B.V. All rights reserved.
Ecological Modelling (0304-3800) (Elsevier), 2009-04 , Vol. 220 , N. 7 , P. 1013-1033

Droits : 2009 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/2009/publication-6782.pdf
DOI:10.1016/j.ecolmodel.2009.01.007
http://archimer.ifremer.fr/doc/00000/6782/