Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
In this study we attempt to understand the water storage variations in a karst aquifer on the Larzac Plateau (South of France) using ground-based gravimetry. Surface to 60 m depth gravity measurements are performed three times a year since 2006 down a pothole, in complement to monthly absolute gravity (AG) measurements at three sites. The time variations of the surface to depth (STD) gravity differences are compared with the AG variations. Using a simple Bouguer plate model, we find that the STD gravity differences are very similar to the AG variations. The STD gravity differences are then used to determine apparent density values. These integrative density values are compared with measured grain densities from core samples to obtain an apparent porosity and saturation change representative of the investigated depth. The apparent porosity ranges from 4.8 to 7.3 per cent. We then discuss on the repartition of the apparent physical properties with respect to the epikarst and infiltration zone karst structures. We argue that AG and STD differences monitor epikarst water storage variations. Within this scope, we discuss the fact that seasonal scale water storage variation occurs predominantly in the epikarst.
ISSN: 0956-540X

hal-00413528
https://hal.archives-ouvertes.fr/hal-00413528
DOI : 10.1111/j.1365-246X.2009.04118.x

Éditeur(s) : HAL CCSD Ecocart Editions
Résumé :  Ouvrage édité avec le concours de : - Union européenne - Préfecture de Guyane, Direction régionale de la recherche et de la technologie - Conseil Régional de Guyane - Conseil Général de Guyane - SEPANGUY - Silvolab-Guyane
Les Plantes comestibles de Guyane présente les espèces ayant un intérêt alimentaire les plus couramment rencontrées à l'état naturel sur le plateau des Guyanes et plus précisément en Guyane française. Classées alphabétiquement, ces plantes sont brièvement décrites par leur morphologie, leur habitat, et, lorsque les fruits sont consommés, leur période de fructification est donnée à titre indicatif. L'index général reprend les noms scientifiques de même que les dénominations vernaculaires dans les différentes langues parlées en Guyane, ces différentes langues étant par grandes ethnies et par familles linguistiques (Créole, Noir marron, Amérindien). Illustré par de nombreux dessins et photos couleurs, cet ouvrage devrait intéresser toutes les personnes désireuses de mieux appréhender l'environnement guyanais.
https://hal.archives-ouvertes.fr/hal-01032120

ISBN : 2-910771-01-6
hal-01032120
https://hal.archives-ouvertes.fr/hal-01032120

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Lateritic surface processes have shaped large platform and cratons of the tropical belt. Constraining the timing of such processes is crucial to decipher their role in cratonic morphogenesis and their response to long-term climatic change and lithospheric deformation. Weathering histories have been documented for South America, Africa and Australia, but precise time constraints of the lateritic weathering processes in South India are still lacking. We present 40Ar/39Ar ages of supergene cryptomelane (K-Mn oxide) formed in the Sandur Mn ore deposits exposed on the highest lateritic paleolandsurface that once covered the Mysore plateau and the adjacent Deccan Traps. Significant 40Ar/39Ar ages are estimated between ~ 36 and ~ 26 Ma from well-defined plateaus in step heating 39Ar release spectra and from best-fitted inverse isochrones. These ages constitute firm time constraints that document intense late Eocene-Oligocene lateritic weathering over Peninsular India under the influence of warm and wet climate comparable to that prevailing in tropical humid forests. These results imply that Southern India was weathered between ~ 36 and 26 Ma and may have been dissected mostly in the Neogene.
ISSN: 0012-821X

Droits : info:eu-repo/semantics/OpenAccess
hal-01097320
https://hal.archives-ouvertes.fr/hal-01097320
https://hal.archives-ouvertes.fr/hal-01097320/document
https://hal.archives-ouvertes.fr/hal-01097320/file/EPSL-D-13-00742R1_HAL.pdf
DOI : 10.1016/j.epsl.2013.11.002

Éditeur(s) : HAL CCSD American Geophysical Union
Résumé : International audience
The aim of this study is to bring new information on water storage dynamics in karst systems from tiltmeter measurements. Newly developed long-base hydrostatic tiltmeters are installed at two sites on the Larzac plateau (France) in a karst aquifer of similar to 100 km(2) recharge area. Each site is located within a karst cave where two tilt directions are monitored. Significant reversible tilt deformation reaching amplitudes of 10(-6) to 10(-5) rad was observed at both sites following heavy precipitation. Elastic parameters were determined with an experiment in which a tiltmeter site was loaded by up to 25 t of weight at strategic locations at the ground surface. Mechanisms responsible for the observed tilt were then examined by means of finite element modeling. Deformation induced by water pressure changes in fractures is our preferred interpretation as the most plausible mechanism. Within this scope, we used the tiltmeter responses to extract time constants using lumped parameter modeling. Time constants are interpreted to be associated with the filling and emptying of fractures nearby the tiltmeters. These instruments therefore appear as useful tools to study the local dynamics of water infiltration in karst systems.
ISSN: 0043-1397

hal-00534461
https://hal.archives-ouvertes.fr/hal-00534461
DOI : 10.1029/2009WR008082

Éditeur(s) : HAL CCSD Society of Exploration Geophysicists
Résumé : Read More: http://library.seg.org/doi/10.1190/geo2015-0411.1
International audience
Understanding the role of the unsaturated zone in aquifer recharge and contaminant attenuation processes is a major challenge for the protection and management of karstic water resources. We present the potential of the magnetic resonance soundings (MRS) geophysical method for characterizing the vadose zone of karst aquifers composed of epikarst and infiltration layers. To investigate the hydraulic functioning of the Durzon karst system located on the Larzac plateau (southern France), we used the MRS method at 16 sites. The MRS results have been compared with available geologic information and to core water content measurements. The remarkable spatial variability of the MRS response observed in the study area makes it possible to determine ranges of water storage properties in relation to the lithology of the investigated carbonate formations (dolomite, marly, and siliceous limestone). All soundings found either constant or increasing MRS water content with depth, which demonstrates that the infiltration zone might be the major water storage entity for permanent water storage, with important consequences for recharge quality and quantity. These results show the feasibility and potential of the MRS method for the characterization of the karst unsaturated zone and for understanding the vertical distribution of water content, which impacts the overall functioning of karst systems.Read More: http://library.seg.org/doi/10.1190/geo2015-0411.1
ISSN: 0016-8033

hal-01412654
https://hal.archives-ouvertes.fr/hal-01412654
https://hal.archives-ouvertes.fr/hal-01412654/document
https://hal.archives-ouvertes.fr/hal-01412654/file/mazilli2016.pdf
DOI : 10.1190/GEO2015-0411.1

Éditeur(s) : HAL CCSD American Geophysical Union
Résumé : International audience
Previous estimates of the geodetic and geologic slip rates of the 1500 km long Altyn Tagh fault bordering the northern edge of the Tibetan plateau vary by a factor of five. Proposed reasons for these discrepancies include poor GPS geometry, interpretative errors in terrace morphology, and changes in fault slip rate over time. Here we present results from a new dense GPS array orthogonal to the fault at ~86.2°E that indicates a velocity of 9.0−3.2/+4.4 mm/yr, in close agreement with geomorphologic estimates at the same location. Our estimated geodetic slip rate is consistent with recent geological slip rates based on terrace offsets. The resulting mean combined geological and geodetic slip rate (9.0 ± 4.0 mm/yr) is remarkably uniform for the central ~800 km of the Altyn Tagh fault, significantly lower than early kinematic estimates and consistent with deformation elsewhere in Tibet and central Asia.
ISSN: 0094-8276

hal-00963568
https://hal.archives-ouvertes.fr/hal-00963568
DOI : 10.1002/2013GL057497

Résumé : Le schéma général de développement du secteur de la pêche en Martinique vise a valoriser de nouveaux secteurs géographiques, il s'agit : - des tombants côtiers (100 à 300m et plus), - de la haute mer (espèces pélagiques), - des bancs du nord de la Guadeloupe, - du plateau guyanais, - à ces domaines pourront s’ajouter les ouvertures sur les autres pays de la Caraïbe grâce à des accords de pêche. Pour cela, les mesures mises en oeuvre ont consisté à promouvoir une pêche au large par la construction de navires de 9 à 11 mètres ("plans-pêche"). Cependant les objectifs fixés n'ont pu être atteints en raison des difficultés successives rencontrées par les plans-pêche pour lesquels plusieurs causes ont été évoquées, portant sur : - le mode de financement de l'outil de pêche, - le matériel et sa maintenance, - les équipages : leur formation, les coutumes locales, - les infrastructures, - la ciguatera sur certains lieux de pêche, - la ressource, jugée insuffisante. Pour remédier à certaines de ces difficultés, une évaluation des ressources potentielles s’est imposée.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00069/18013/15541.pdf
http://archimer.ifremer.fr/doc/00069/18013/

Éditeur(s) : HAL CCSD AGU and the Geochemical Society
Résumé : International audience
[1] Statistical analysis of modern oceanic subduction zone parameters, such as the age of a downgoing plate or the absolute plate motions, is performed in order to investigate which parameter controls the dip of a slab and, conversely, what the influence of slab geometry is on upper plate behavior. For that purpose, parameters have been determined from global databases along 159 transects from all subduction zones that are not perturbed by nearby collision or ridge/plateau/seamount subduction. On the basis of tomographic images, slabs that penetrate through, or lie on, the 670 km discontinuity are also identified. The results of the statistical analysis are as follows: (1) Back-arc stress correlates with slab dip, i.e., back-arc spreading is observed for deep dips (deeper than 125 km) larger than 50°, whereas back-arc shortening occurs only for deep dips less than 30°. (2) Slab dip correlates with absolute motion of the overriding plate. The correlation is even better when the slab lies on, or even more penetrates through, the 670 km discontinuity. (3) Slabs dip more steeply, by about 20° on average, beneath oceanic overriding plates than beneath continental ones. (4) Slabs dip more steeply on average by about 10° near edges. (5) Slab dip does not correlate with the magnitude of slab pull, the age of subducting lithosphere at the trench, the thermal regime of the subducting lithosphere, the convergence rate, or the subduction polarity (east versus west). The present study provides evidence that the upper plate absolute motion plays an important role on slab dip, as well as on upper plate strain. Retreating overriding plates are often oceanic ones and thus may partially explain the steeper slab dips beneath oceanic upper plates. One can infer that low slab dips correlate well with compression in continental advancing upper plates, whereas steep dips are often associated with extension in oceanic retreating upper plates. Excess weight of old slabs is often counterbalanced by other forces, probably asthenospheric in origin, such as lateral mantle flow near slab edges or anchor forces, to determine slab dip. Components: 12,676 words, 13 figures, 1 table.
ISSN: 1525-2027

hal-01261567
https://hal.archives-ouvertes.fr/hal-01261567
https://hal.archives-ouvertes.fr/hal-01261567/document
https://hal.archives-ouvertes.fr/hal-01261567/file/lallemandG32005.pdf
DOI : 10.1029/2005GC000917

Éditeur(s) : HAL CCSD American Geophysical Union
Résumé : International audience
The region of Bhutan is thought to be the only segment of the Himalayas not having experienced a major earthquake over the past half millennium. A proposed explanation for this apparent seismic gap is partial accommodation of the India-Asia convergence further south across the Shillong Plateau, yet the seismic behavior of the Himalayan megathrust in Bhutan is unknown. Here we present historical documents from the region reporting on an earthquake in 1714 A.D. and geological evidence of surface rupture to constrain the latest large event in this area. We compute various earthquake scenarios using empirical scaling relationships relating magnitude with intensity, source location and rupture geometry. Our results constrain the 1714 A.D. earthquake to have ruptured the megathrust in Bhutan, most likely during a M7.5–8.5 event. This finding reclassifies the apparent seismic gap to a former information gap and implies that the entire Himalayan arc has a high level of earthquake potential.
ISSN: 0094-8276

hal-01467822
https://hal.archives-ouvertes.fr/hal-01467822
DOI : 10.1002/2016GL071033

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
Oxidative stress and haemolysis-associated nitric oxide (NO) depletion plays a crucial role in the development of vasculopathy in sickle cell anaemia (SS). However it remains unknown whether oxidative stress and haemolysis levels influence vascular function in patients with sickle haemoglobin C disease (SC). Microvascular response to heat (using Laser Doppler flowmetry on finger), oxidative stress biomarkers, NO metabolites, endothelin-1 and haematological parameters were compared between patients with SS and SC. Vascular function, oxidative and nitrosative markers were also measured in healthy (AA) children. SS and SC had increased plasma advanced oxidation protein products (AOPP), malondialdehyde, plasma antioxidant activities and NO end products, compared to AA. SC had lower catalase activity compared to AA and SS. Haemolytic rate, glutathione peroxidase and nitrotyrosine concentrations were significantly increased in children with SS compared to SC and AA. SS and SC had impaired microvascular reactivity compared to AA. In SS, the plateau phase of the response to local thermal heating was negatively associated with nitrotyrosine and AOPP. No association between vascular function parameters and oxidative stress markers was observed in SC. Mild haemolysis in SC, compared to SS, may limit oxidative and nitrosative stress and could explain the better preserved microvascular function in this group.
ISSN: 0007-1048

hal-01668314
https://hal.univ-antilles.fr/hal-01668314
DOI : 10.1111/bjh.14693

Résumé : La pêche et la riziculture font partie des secteurs économiques les plus importants du Surinam. Depuis près de 30 ans, la riziculture par poldérisation des zones basses et marécageuses a permis de mettre en valeur toute la bande littorale de l’ouest du pays ; cette culture s’accroit encore aujourd’hui de façon significative. Le secteur halieutique quant à lui regroupe d’une part une pêche industrielle exploitant les crevettes du plateau continental et d’autre part une pêche artisanale traditionnelle qui recherche essentiellement les poissons sur les petits fonds côtiers et dans les marais saumâtres.

Droits : 1985 Ifremer
http://archimer.ifremer.fr/doc/00071/18272/15839.pdf
http://archimer.ifremer.fr/doc/00071/18272/

Éditeur(s) : HAL CCSD Elsevier
Résumé : We present new analytical data from lavas and associated rocks dredged and/or drilled from the South Fiji Basin, Northland Plateau, Colville Ridge and Havre Trough. These results provide much-needed ground truth about the geology, age and tectonic evolution of the Cenozoic submarine ridges and basins between the active intraoceanic Tonga–Kermadec arc, and rifted continental borderlands of New Zealand, the Norfolk Ridge and New Caledonia. Key results from this study include: (1) Ar–Ar dates on Minerva Abyssal Plain oceanic crust suggest that the ages of magnetic anomalies in the South Fiji Basin have been overestimated by earlier workers; (2) subduction-related lavas are widespread across the region, are not presently organised into arc-like chains, and cluster in the age range 22–18 Ma (Early Miocene); (3) the oldest subduction-related lavas occur in the western part of the region (32–26 Ma: Norfolk and Three Kings Ridge); (4) shoshonites, interpreted as rifted arc lavas, were erupted in a narrow 20–21 Ma interval over a wide area. Put together, these results indicate high magmatic flux and large and rapid horizontal tectonic translations and basin opening from 18–23 Ma in the region immediately north of New Zealand. We explain the Miocene tectonomagmatic development of the region by a model of rapid rollback of a single, east-facing Pacific arc–trench system that became established after Northland Allochthon emplacement. Critical testing of this, versus other, tectonic models must await drilling and dating of thus-far unsampled Kupe Abyssal Plain crust.
ISSN: 0025-3227

hal-00405803
https://hal.archives-ouvertes.fr/hal-00405803
DOI : 10.1016/j.margeo.2006.10.033

Éditeur(s) : American Geophysical Union
Résumé : The Fairway Ridge is a buried continental structure that separates the Fairway Basin from the New Caledonia Basin. The proposed Cretaceous age of the Fairway Basin has remained highly hypothetical to date. Deep offshore petroleum exploration wells revealed well-dated Mesozoic carbonaceous sedimentary rocks in the Taranaki Basin at the southern end of the Aotea Basin. In this paper we use geophysical data to confirm the continuity of the 2000 km long Fairway-Aotea Basin connecting New Caledonia to New Zealand and prove its early Late Cretaceous age. Analysis of seismic reflection profiles together with newly compiled gravity and magnetic maps reveals Late Cretaceous NE–SW trending lineaments projecting northeastward from major Tasman Sea fracture zones and the Bellona Trough, which demonstrate that the opening of the Fairway-Aotea Basin predates the opening of the Tasman Sea. This result combined with observations of the Mesozoic regional geology suggests that the Lord Howe, Fairway, and Norfolk ridges are part of a remnant late Early Cretaceous continental arc, which was fragmented into three pieces by the late Early to early Late Cretaceous. This event might be contemporaneous with a plate motion change between the Gondwana and Pacific plates and/or the arrival of the Hikurangi plateau in the subduction zone around 105 Ma, which caused the cessation of subduction along this plate boundary. We interpret either of those two events as being possible trigger events for the post–Early Cretaceous fragmentation of the eastern Gondwana margin in a slab retreat process.
Geochemistry Geophysics Geosystems - G3 (1525-2027) (American Geophysical Union), 2009-12 , Vol. 10 , N. 12 , P. 1-24

Droits : 2009 American Geophysical Union
http://archimer.ifremer.fr/doc/2009/publication-7322.pdf
DOI:10.1029/2009GC002612
http://archimer.ifremer.fr/doc/00000/7322/

Éditeur(s) : HAL CCSD
Résumé : In this paper we report a study of the mating system and gene flow of Sextonia rubra, a hermaphroditic, insect pollinated tropical tree species with a geographic distribution in the Guyana Plateau and the Amazon. Using five microsatellites we analysed 428 seeds of 27 open pollinated families at the experimental site "Paracou" in French Guiana. We observed, compared to other tropical tree species, a high level of genetic diversity. We estimated parameters of the mating system and gene flow by using the mixed mating model and the TwoGenerapproach. The estimated multilocus outcrossing rate, tm, was 0.992 indicating nearly complete outcrossing. A significant level of biparental inbreeding and a small proportion of full-sibs were estimated for the 27 seed arrays. The differentiation of allelic frequencies among the pollen pools was ΦFT = 0.061. We estimated mean pollen dispersal distances between 65 m and 89 m according to the dispersal models used. The joint estimation of pollen dispersal and density of reproductive trees gave an effective density estimate of 2.1-2.2 trees/ha
Silvae genetica

hal-01031483
https://hal.archives-ouvertes.fr/hal-01031483

Éditeur(s) : HAL CCSD
Résumé : 1 p.
International audience
The 12th May 2008 Wenchuan earthquake in the Longmen Shan occurred on a large thrust fault largely inherited from an Indosinian structure itself probably controlled by an older structural heritage of the South China block continental margin. Within the whole northeast Tibet region, such a structural inheritance has had a major impact on the Tertiary deformation. It appears of primary importance to assess the pre-Tertiary tectonic evolution of the main blocks involved to understand the actual deformation in the eastern edge of Tibet. Over the past decades, the Proterozoic to Cenozoic tectonic, metamorphic and geochronologic history of the Longmen Shan and Songpan Garzê area have been largely studied. We present a synthesis of the tectonic evolution of the Songpan Garzê fold and thrust belt from Triassic to present. The Songpan-Garzê belt was formed during closure of a wide oceanic basin ?lled with a thick (5 to 15 km) sequence of Triassic ?yschoid sediments. Closure of the basin due to Triassic subduction involved strong shortening, intense folding and faulting of the Triassic series. A large-scale décollement, that presently outcrops along the eastern boundary of the belt (Danba area), allowed the growth of a wide and thick accretionary wedge. It develops in the Paleozoic and Triassic series and separates the accretionary prism from an autochthonous crystalline basement which shares many similarities with the basement of the Yangtze Craton (0.7-0.9 Ga). To the north and northwest, below the thickened Triassic series of the belt, the composition (oceanic or continental) of the basement remains unknown. During the Indosinian orogeny the emplacement of orogenic granites (220 - 150 Ma) was associated to crustal thickening. The isotopic composition of granitoids shows that their magma source were predominantly derived from melting of the proterozoic basement with varying degrees of sedimentary material and negligible mantle source contribution. In the Danba area, the décollement outcrops in a large tertiary antiform with a NNW-SSE axis. It has been exhumed too in the hanging wall of the NE-SW faults of the Tertiary Longmen-Shan belt that marks the present day transition from the Tibetan plateau to the Sichuan basin. These faults have episodically absorbed signi?cant shortening since the Late Triassic. The amount and precise timing of post-triassic deformation are dif?cult to constrain especially because of the dif?culty to isolate the tertiary thermochronological signal from the protracted late Triassic - Cretaceous thermal history. Nonetheless it is generally accepted that Jurassic - Cretaceous tectonism did not modi?ed the general Triassic architecture of eastern Tibet contrarily to the Tertiary deformation. The long-term cooling histories obtained on Mesozoic granites and on the metamorphic series of the Danba dome are very similar showing a very slow and regular cooling during Jurassic andCretaceous, con?rming the absence of major tectonic event between c.a. 150 and 30 Ma. Low temperature thermochronology data indicate that ?nal exhumation and cooling occurred in theTertiary with an acceleration between 10 and 5 Ma along the major tectonic structures. Within the Longmen Shan range, a total denudation of 7 to 10 km is estimated for the late Cenozoic period. Similar amounts of late Tertiary denudation have been estimated along an east-west section across the Xianshuihe fault
Asian climate and tectonics seminar
Utrecht, Netherlands

insu-00610298
https://hal-insu.archives-ouvertes.fr/insu-00610298
DOI : 10.1016/j.jseaes.2010.03.008

Éditeur(s) : HAL CCSD Wiley-Blackwell
Résumé : International audience
We explore the tectono-magmatic processes in the western West Philippine Basin, Philippine Sea Plate, using bathymetric data acquired in 2003 and 2004. The northwestern part of the basin formed through a series of northwestward propagating rifts. We identify at least five sequences of propagating rifts, probably triggered by mantle flow away from the mantle thermal anomaly that is responsible for the origin of the Benham and Urdenata plateaus. Gravitational forces caused by along-axis topographic gradient and a ∼30° ridge reorientation appear to also be driving the rift propagations. The along-axis mantle flow appears to be reduced and deflected along the Luzon-Okinawa fracture zone, because the spreading system remained stable west of this major fault zone. North-east of the Benham plateau, a left-lateral fracture zone has turned into a NE–SW-trending spreading axis. As a result, a microplate developed at the triple junction.
ISSN: 0954-4879

insu-00304360
https://hal-insu.archives-ouvertes.fr/insu-00304360
DOI : 10.1111/j.1365-3121.2008.00824.x

Éditeur(s) : Elsevier Science Bv
Résumé : There has been growing interest in the development of mud crab aquaculture in New Caledonia. However, for this to become established at a commercial level, a cost-effective formulated feed based on internationally-available ingredients needs to be developed. We have evaluated the optimal dietary protein content for juvenile crabs, Scylla serrata (Forskål, 1775), using a series of diets with a protein content ranging from 27 to 49% and soy protein concentrate (SPC) as the main protein source. For this purpose, 54 individually housed crabs were allocated to five dietary treatments (n = 10 or 11). The crabs were fed ad libitum, for 81 days with the allocated diets. The apparent digestibilities of dry mater, crude protein and energy were high (96.2-97.3%), irrespective of the diet. The voluntary feed intake (VFI) of crabs widely varied from 46 to 220 g kg- 1of fresh initial body weight per week (iBW week- 1) whatever the diet. However, SPC intake and protein intake increased significantly with dietary protein content up to the diet with 40% crude protein, but did not increase further with diets containing 44% and 49% crude protein. The cumulative molts were strongly affected by the VFI levels or energy intake and also, to a lesser extent, by the levels of SPC or protein in diets. Two phases in tissue gain were observed after ecdysis: an initial deposition phase lasting around 30 days followed by a plateau which lasted until the next molt. The daily tissue growth was 16.5% of dry body weight (dry BW) one day after ecdysis and dramatically decreased to 3.6% of dry BW over the first 10 days, then decreased more slowly to the minimum value of 1.3% of dry BW over the next 70 days. During the course of experiment, the best growth (tissue growth and molt frequency) and the best feed efficiency (FCR, PER, retention of proteins and lipids) were obtained with crabs fed on the diet with 40% crude protein. This result was confirmed by a bioenergetic study which showed significantly higher allocation of the energy intake for growth (RE) of crabs fed on diet 40% crude protein. Finally, under our experimental conditions, 1 kg of juvenile crabs required 6.5 ± 1.1 g of protein per day. This level was obtained with the diet SPC-42 that contained 40% of protein of which almost three quarters were derived from SPC. Two hypotheses are proposed to explain the negative effect of high level of SPC or protein on growth and feed efficiency for crabs fed on in diets containing 52% and 60% SPC.
Aquaculture (0044-8486) (Elsevier Science Bv), 2014-10 , Vol. 434 , P. 499-509

Droits : 2014 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/00211/32196/30630.pdf
http://archimer.ifremer.fr/doc/00211/32196/

Éditeur(s) : HAL CCSD Elsevier
Résumé : TAG LITHO
In this study we attempt to understand the water storage variations in a karst aquifer on the Larzac Plateau (South of France) using absolute gravimetry. On this karst system, water input is exclusively rainfall and draining occurs at the Durzon perennial spring in a karstic valley. Our basis assumption is that water storage in the vadose zone (epikarst and infiltration zone) has a significant effect on surface gravity through Newtonian attraction. The karst aquifer is hence being monitored since January 2006 with monthly absolute gravity measurements at three sites. The gravity measurements are corrected for regional scale gravity using water storage models in order to obtain gravity variations related exclusively to the local water storage variations. The gravity variations exhibit an important seasonal component (10-15 mu gal corresponding to a variation of equivalent water stab thickness of similar to 24-36 cm). Water storage variation seen by gravimetry is not spatially uniform on the studied karst system, corroborating current geomorphologic observations and interpretations. Finally, we use a global mass balance consideration linking rainfall, evapotranspiration and spring discharge to provide a conceptual framework for the understanding of observed gravity variations.
ISSN: 0022-1694

hal-00411884
https://hal.archives-ouvertes.fr/hal-00411884
DOI : 10.1016/j.jhydrol.2008.06.020

Résumé : La pêche au poisson rouge connaît un essor spectaculaire en Guyane depuis quelques années, parallèlement à une demande croissante du marché antillais pour ce produit, L'appellation vivaneau ou poisson rouge, regroupe un certain nombre de genres et d'espèces de la famille des Lutjanidés, présents dans toute la région des Caraïbes. Il semble que le plateau guyanais, pour avoir depuis longtemps attiré des pêcheurs étrangers, soit particulièrement intéressant par ses rendements élevés en ces espèces et également par l'absence de ciguatera, Actuellement, cette ressource est exploitée en Guyane dans le cadre des règlements communautaires et notamment sous le régime de licences délivrées aux pays tiers par 26 unités, à savoir 25 navires vénézuéliens travaillant à la ligne, la nasse ou la palangre, et 1 chalutier martiniquais. Depuis le début des années 80, les tonnages mis à terre en Guyane augmentent et font du vivaneau la seconde ressource halieutique hauturière du département, après la crevette. Dans le cadre du développement régional , l'Ifremer a donc entrepris un programme de recherche sur les potentialités réelles en poisson rouge de la zone Economique Exclusjve (ZEE) de manière à proposer rapidement des mesures appropriées de gestion des stocks et d'aménagement de la pêcherie. Dans un premier temps, ce rapport qui finalise une convention conclue entre le Conseil Régional de la Guyane et I'IFREMER, vise à faire un état des connaissances biologiques et un bilan de la situation actuelle de la pêcherie.

Droits : 1988 Ifremer
http://archimer.ifremer.fr/doc/00087/19811/17452.pdf
http://archimer.ifremer.fr/doc/00087/19811/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Since Deccan Traps extrusion ~ 65 Ma ago, thick weathering mantles have developed over Peninsular India on both the western coastal lowland and adjacent plateau separated by the Western Ghats Escarpment. Manganiferous lateritic profiles formed by supergene weathering of Late Archean manganiferous protores are exposed on paleolandsurface remnants on both sides of the escarpment. Petrological and geochemical characterizations of samples from those Mn lateritic profiles allowed identifying cryptomelane (K-Mn oxide) dated by 40Ar/39Ar geochronology. The ages obtained document major weathering periods, ca. 53-50 Ma, and ca. 37-23 Ma in the highland, and ca. 47-45 Ma, ca. 24-19 Ma and discrete weathering pulses at ~ 9 Ma and ~ 2.5 Ma in the lowland. Old ages of the highland (53-50 Ma) and the lowland (47-45 Ma) indicate synchronous lateritic weathering across the escarpment at a time the peninsula started to drift across the equatorial belt. Intense weathering periods at ca. 53-45 and ca. 37-23 Ma are interpreted to reflect the Early Eocene climatic optimum and the onset of Asian monsoon regimes, respectively. The ages further indicate that most of the dissection of the highland must have taken place after ~ 23 Ma, whereas the lowland was weakly incised essentially after ~ 19 Ma. Our results also document divergent erosion and weathering histories of the lowland and the highland after the Eocene, suggesting installation of a dual climatic regime across the Western Ghats escarpment.
ISSN: 0009-2541

ird-01419899
http://hal.ird.fr/ird-01419899
http://hal.ird.fr/ird-01419899/document
http://hal.ird.fr/ird-01419899/file/CHEMGE9048R2.va.pdf
DOI : 10.1016/j.chemgeo.2016.04.018