Éditeur(s) : HAL CCSD Elsevier
Résumé : This contribution reports our preliminary work to determine Cu isotope ratios for various granite rocks and examine the Cu isotope systematics within granite suites. A chemical procedure, modified from Marechal [Marechal, C.N., Telouk, R and Albarede, F., 1999. Precise analysis of copper and zinc isotopic compositions by plasma-source mass spectrometry. Chemical Geology, 156(1-4): 251-273.], Was used to separate Cu from rock matrix. Quantitative recovery (100.6 +/- 1.6%), with a low total procedural blank (2.65 +/- 0.66 ng) for Cu, has been achieved, allowing Cu isotopic measurements on samples with as little as 10 ppm Cu. The Cu isotope ratios (delta Cu-65 relative to NIST SRM 976) of 32 rock samples, ranging from mafic to felsic compositions, from 3 batholiths (2 I-type, 1 S-type) from the Lachlan Fold Belt in southeastern Australia. vary from -0.46 parts per thousand to 1.51 parts per thousand. Most of them cluster around zero, With mean values for the I-type and S-type granites of 0.03 +/- 0.15 parts per thousand and - 0.03 +/- 0.42 parts per thousand (2 sigma) respectively. These data, together with Cu isotope ratios of two loess samples, provide preliminary evidence that the baseline Cu isotopic composition of the crystalline part of upper continental crust is close to zero. The tight clustering of Cu isotope ratios of rocks from the I-type suites Suggests that high-temperature magmatic processes do not produce significant Cu isotope fractionation. However, two granites with abnormally heavy Cu isotope signatures (up to 1.51 parts per thousand) appears to be the result of localized hydrothermal alteration. Measurable variation in Cu isotopic composition of the S-type granite may reflect isotopic heterogeneity in the sedimentary Source region as a result of redox processes or may be due to hydrothermal overprinting. Thus, Cu isotope geochemistry may be a useful tracer for studying hydrothermal alteration and Source heterogeneity of granitic rocks.
ISSN: 0009-2541

hal-00413130
https://hal.archives-ouvertes.fr/hal-00413130
DOI : 10.1016/j.chemgeo.2008.06.047

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
A suite of eclogite xenoliths from the Roberts Victor kimberlite (South Africa) is remarkable for its high abundances of base metal sulfides (BMS; up to 2 modal %). However, while sulfides are nearly ubiquitous in Type I eclogites (garnet > 0.07% Na2O), Type II eclogites (garnet < 0.07% Na2O) systematically lack sulfides. Two different sulfide assemblages are recognised within the Type I xenolith suite. Both populations are polyphase Cu-Ni-Fe sulfides, one characterised by the pyrrhotite (Po) + pentlandite (Pn) + chalcopyrite (Cp) assemblage and the other by the smythite/violarite (Smy/Vi) + (Ni)pyrite (Py) + Cp assemblage. The latter is the most abundant assemblage and reflects the supergene alteration of the "primary" Po + Pn + Cp assemblage. This process overprints the original composition of the sulfides by remobilising elements such as S, Fe, Ni, Se and Te. In the Type I eclogites, BMS occur as inclusions within silicates (garnet and clinopyroxene) and as interstitial grains. No chemical differences were observed between enclosed and interstitial sulfides. However, their relative abundances are correlated, indicating a similar origin. The Po + Pn + Cp assemblage is identical to eclogitic sulfides previously described in some Roberts Victor diamonds. Silicate-enclosed sulfides could appear to be early phases, but they are restricted to the outer parts of the silicate grains, suggesting a late incorporation during partial recrystallisation of silicate phases, induced by fluid-rock percolation-reaction during a metasomatic event. Positive whole-rock correlations between Se and (La/Sm)N⁎ and between Cu and ΣLREEN⁎ indicate a direct link between sulfide content and the enrichment of Mg + incompatible elements in the Type I eclogites, further supporting a metasomatic origin of the sulfide component. Similarly, a negative correlation between ΣLREEN⁎ and Cucpx implies that the metasomatic agent was at least partially composed of S-rich fluid (e.g. H2S, SO2) that reacted with the rock and leached Cu out of the silicates. The coupling between sulfides and LREE in the Type I eclogites, as well as the absence of sulfides and metasomatic features (e.g. unequilibrated grain boundaries, melt pockets, fluid inclusions, phlogopite) in the Type II eclogites, demonstrate that Type II eclogites did not undergo such a metasomatic event and therefore may represent the less-modified protoliths of Type I eclogites.
ISSN: 0009-2541

hal-00903856
https://hal.archives-ouvertes.fr/hal-00903856
DOI : 10.1016/j.chemgeo.2013.06.015

Éditeur(s) : HAL CCSD Elsevier Masson
Résumé : International audience
When fish larvae recruit back to a reef, chemical cues are often used to find suitable habitat or to find juvenile or adult conspecifics. We tested if the chemical information used by larvae was intentionally produced by juvenile and adult conspecifics already on the reef (communication process) or whether the cues used result from normal biochemical processes with no active involvement by conspecifics (“spying” behavior by larvae). Conspecific chemical cues attracted the majority of larvae (four out of the seven species tested); although while some species were equally attracted to cues from adults and juveniles (Chromis viridis, Apogon novemfasciatus), two exhibited greater sensitivity to adult cues (Pomacentrus pavo, Dascyllus aruanus). Our results indicate also that spying cues are those most commonly used by settling fishes (C. viridis, P. pavo, A. novemfasciatus). Only one species (D. aruanus) preferred the odour of conspecifics that had had visual contact with larvae (communication).
ISSN: 1631-0691

hal-01212899
https://hal-univ-perp.archives-ouvertes.fr/hal-01212899
DOI : 10.1016/j.crvi.2015.05.004

Éditeur(s) : HAL CCSD Laboratoire Arago
Résumé : International audience
As it is unlikely that successful settlement is solely a matter of chance (i.e. tofind a suitable habitat), one of the greatest challenges facing the fish larvae is how to locate therelatively rare patches of coral reef habitat on which they settle and ultimately reside as adults.The answer must lie partly in the sensory modalities of fishes at settlement. Habitat selection isonly possible if fish larvae could detect some environmental cues to select a suitable reef habitatat settlement. The present review aims at providing the latest works dealing with informationperception in coral reef fish larvae at settlement. Two decades ago, it was generally assumedthat larval behaviors and sensory abilities at settlement were considered too feeble to significantlyaffect dispersal outcomes. Several recent studies showed that recognition of suitable reefhabitats by fish larvae at settlement is based on a combination of visual, chemical and acousticcues. The first part of our review shows the main advances in the knowledge of visual, chemicaland acoustic cues used by fish larvae to detect an island, a reef, a micro-habitat, a conspecific orsome predators. The second part of our review deals with the effect of imprinting and/or innatecapabilities. The third part focuses on the different cues used at different scales and underlinessome contradictory results about the distance of transmission and detection of chemical andacoustic cues in coral reefs. Finally, as global and regional environmental changes have stressedcoral reefs to such an extent that they are either destroyed or in decline, the fourth part presentsthe effects of both anthropogenic and environmental stressors on information perception andresponse capacities in coral reef fish larvae. If polluted seawater disrupts the larval abilities tofind a suitable reef habitat, fish larvae may spend more time in the planktonic environment,resulting in increased energetic costs and predation risk, and consequently a lower larval settlement.We hypothesise that as the stability of fish communities is dependent, in part, on the stabilityof social interactions, the disruption of “larvae-habitat relationships” can have major consequencesfor larval settlement into adult population with further repercussions for the ecosystemas a whole. Overall, larval settlement of coral reef fish is an excellent example of the complexityof interactions between an organism and its environment as without perceiving environmentalcues, fish larva would have very little chance of selecting a suitable reef habitat. Moreover,understanding the relationship between reef state and settlement potential will allow managementplanning for the maintenance of coral reefs that are increasingly degraded.
ISSN: 0240-8759

hal-01191776
https://hal-univ-perp.archives-ouvertes.fr/hal-01191776

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
Despite a relatively 'uniform' fertile composition (Al2O3 = 2 center dot 19-4 center dot 47 wt %; Fo% = 89 center dot 2 +/- 0 center dot 3%; Cr#(Spl) = 8 center dot 9 +/- 1 center dot 5%), the Montferrier peridotite xenoliths show a wide range of S contents (22-590 ppm). Most sulphides are interstitial and show peculiar pyrrhotite-pentlandite intergrowths and low abundances of Cu-rich phases. Sulphide-rich samples are characterized by strong enrichment in the light rare earth elements and large ion lithophile elements without concomitant enrichment of the high field strength elements. Such trace-element fractionation is commonly ascribed to metasomatism by volatile-rich melts and/or carbonatitic melts. S and Se (11-67 ppb), as well as S/Se (up to approximate to 12 000), are correlated with La/Sm. Cu, however, remains broadly constant (30 +/- 5 ppm). These features strongly suggest that the percolation-reaction of such volatile-rich fluids has led to sulphide enrichment with an atypical signature marked by strong fractionation of the chalcophile elements (i.e. S vs Se and Cu). S-rich xenoliths are also characterized by high (Pd/Ir)(N) (1 center dot 2-1 center dot 9; where subscript N indicates normalized to chondrite), (Pd/Pt)(N) between 1 center dot 5 and 2 center dot 2, and (Os/Ir)(N) up to 1 center dot 85. Despite the relative uniform fertile composition of the xenoliths, Re/Os ranges between 0 center dot 02 and 0 center dot 18. Os-187/Os-188 is extremely variable even within a single sample and can be as high as 0 center dot 1756 for the most S-rich samples. Sulphides show highly fractionated and variable abundances of the highly siderophile elements (HSE) [0 center dot 03 (Pd/Ir)(N) < 1283] and Re-Os isotopic composition (0 center dot 115 < Os-187/Os-188 < 0 center dot 172). Such variation can be observed at the thin-section scale. Whole-rock and in situ sulphide data demonstrate that chalcophile and HSE systematics and the Os isotopic composition of the upper mantle could be significantly modified through metasomatism, even with volatile-rich fluids. These features highlight the complex behaviour of the HSE in fluid-rock percolation-reaction models and suggest a complex interplay between sulphide addition (crystallization or sulphidation) and partial equilibration of pre-existing sulphide. The specific fractionations observed in chemical proxies such as S and Se, Os and Ir, and Pd and Pt, as well as the low abundance of Cu-rich sulphides, suggest that sulphide addition may not have occurred via sulphide melts. Rather, we infer that S was present as a dissolved species in a (supercritical) oxidizing, volatile-rich fluid (C-O-H-S +/- Cl) along with other chalcophile and siderophile elements such as Os, Pd, Re and Au. The highly radiogenic Os composition of this fluid ( Os-187/ Os-188 > 0 center dot 17) would imply that such fluids are derived from an uncommon type of mantle source possibly related to carbonatite melts.
ISSN: 0022-3530

hal-00644524
https://hal.archives-ouvertes.fr/hal-00644524
DOI : 10.1093/petrology/egr038

Éditeur(s) : HAL CCSD Nature Publishing Group
Résumé : International audience
Lateralization, i.e. the preferential use of one side of the body, may convey fitness benefits for organisms within rapidly-changing environments, by optimizing separate and parallel processing of different information between the two brain hemispheres. In coral reef-fishes, the movement of larvae from planktonic to reef environments (recruitment) represents a major life-history transition. This transition requires larvae to rapidly identify and respond to sensory cues to select a suitable habitat that facilitates survival and growth. This ‘recruitment’ is critical for population persistence and resilience. In aquarium experiments, larval Acanthurus triostegus preferentially used their right-eye to investigate a variety of visual stimuli. Despite this, when held in in situ cages with predators, those larvae that previously favored their left-eye exhibited higher survival. These results support the “brain’s right-hemisphere” theory, which predicts that the right-eye (i.e. left-hemisphere) is used to categorize stimuli while the left-eye (i.e. right-hemisphere) is used to inspect novel items and initiate rapid behavioral-responses. While these experiments confirm that being highly lateralized is ecologically advantageous, exposure to chlorpyrifos, a pesticide often inadvertently added to coral-reef waters, impaired visual-lateralization. This suggests that chemical pollutants could impair the brain function of larval fishes during a critical life-history transition, potentially impacting recruitment success.
ISSN: 2045-2322

Droits : http://creativecommons.org/licenses/by/
hal-01585550
http://hal.upmc.fr/hal-01585550
http://hal.upmc.fr/hal-01585550/document
http://hal.upmc.fr/hal-01585550/file/s41598-017-09381-0.pdf
DOI : 10.1038/s41598-017-09381-0

Éditeur(s) : HAL CCSD American Institute of Physics
Résumé : International audience
Laser-induced periodic surface structures (LIPSS) were formed on Cu/Si or Cu/glass thin films using Nd:YAG laser beam (40 ps, 10Hz, and 30mJ/cm2). The study of ablation threshold is always achieved over melting when the variation of the number of pulses increases from 1 to 1000. But the incubation effect is leading to reduce the threshold of melting as increasing the number of laser pulse. Also, real time reflectivity signals exhibit typical behavior to stress the formation of a liquid phase during the laser-processing regime and helps to determine the threshold of soft ablation.Atomic Force Microscopy (AFM) analyses have shown the topology of the micro-crater containing regular spikes with different height. Transmission Electron Microscopy (TEM) allows finally to show three distinguished zones in the close region of isolated protrusions. The central zone is a typical crystallized area of few nanometers surrounded by a mixed poly-crystalline and amorphous area. Finally, in the region far from the protrusion zone, Cu film shows an amorphous structure. The real time reflectivity, AFM, and HR-TEM analyses evidence the formation of a liquid phaseduring the LIPSS formation in the picosecond regime. VC 2015 AIP Publishing LLC
ISSN: 0003-6951

hal-01226065
https://hal.archives-ouvertes.fr/hal-01226065
DOI : 10.1063/1.4935413

Éditeur(s) : HAL CCSD Royal Society of Chemistry
Résumé : International audience
Chemical mediation regulates behavioral interactions between species and thus affects population structure,community organization and ecosystem function. Among marine taxa that have developed chemicalmediation strategies, gastropods belong to a diverse group of molluscs found worldwide, including specieswith a coiled, reduced or absent shell. Most gastropods use natural products to mediate a wide range ofbehaviors such as defense, prey location or interactions with con- and hetero-geners. Their chemicallydefended diet, such as cyanobacteria, algae, sponges, bryozoans and tunicates, provides them witha considerable opportunity either as shelter from predators, or as a means to enhance their own chemicaldefense. In addition to improving their defenses, molluscs also use prey secondary metabolites in complexchemical communication including settlement induction, prey detection and feeding preferences. Theassimilation of prey secondary metabolites further provides the opportunity for interactions withconspecifics via diet-derived chemical cues or signals. This review intends to provide an overview on thesequestration, detoxification, and biotransformation of diet-derived natural products, as well as the role ofthese compounds as chemical mediators in gastropod-prey interactions.
ISSN: 0265-0568

hal-01563402
https://hal-univ-perp.archives-ouvertes.fr/hal-01563402
DOI : 10.1039/c6np00097e

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Marine organisms are under threat globally from a suite of anthropogenic sources, but the current emphasis on global climate change has deflected the focus from local impacts. While the effect of increased sedimentation on the settlement of coral species is well studied, little is known about the impact on larval fish. Here, the effect of a laterite “red soil” sediment pollutant on settlement behaviour and post-settlement performance of reef fish was tested. In aquarium tests that isolated sensory cues, we found significant olfaction-based avoidance behaviour and disruption of visual cue use in settlement-stage larval fish at 50 mg L−1, a concentration regularly exceeded in situ during rain events. In situ light trap catches showed lower abundance and species richness in the presence of red soil, but were not significantly different due to high variance in the data. Prolonged exposure to red soil produced altered olfactory cue responses, whereby fish in red soil made a likely maladaptive choice for dead coral compared to controls where fish chose live coral. Other significant effects of prolonged exposure included decreased feeding rates and body condition. These effects on fish larvae reared over 5 days occurred in the presence of a minor drop in pH and may be due to the chemical influence of the sediment. Our results show that sediment pollution of coral reefs may have more complex effects on the ability of larval fish to successfully locate suitable habitat than previously thought, as well as impacting on their post-settlement performance and, ultimately, recruitment success.
ISSN: 0029-8549

hal-01270670
https://hal-univ-perp.archives-ouvertes.fr/hal-01270670
DOI : 10.1007/s00442-015-3367-6

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Marine organisms are under threat globally from a suite of anthropogenic sources, but the current emphasis on global climate change has deflected the focus from local impacts. While the effect of increased sedimentation on the settlement of coral species is well studied, little is known about the impact on larval fish. Here, the effect of a laterite “red soil” sediment pollutant on settlement behaviour and post-settlement performance of reef fish was tested. In aquarium tests that isolated sensory cues, we found significant olfaction-based avoidance behaviour and disruption of visual cue use in settlement-stage larval fishat 50 mg L−1, a concentration regularly exceeded in situ during rain events. In situ light trap catches showed lower abundance and species richness in the presence of red soil, but were not significantly different due to high variance in the data. Prolonged exposure to red soil produced altered olfactory cue responses, whereby fish in red soil made a likely maladaptive choice for dead coral compared to controls where fish chose live coral. Other significant effects of prolonged exposure included decreased feeding rates and body condition. These effects on fish larvae reared over 5 days occurred in the presence of a minor drop in pH and may be due to the chemical influence of the sediment. Our results show that sediment pollution of coral reefs may have more complex effects on the ability of larval fish to successfully locate suitable habitat than previously thought, as well as impacting on their post-settlement performance and, ultimately, recruitment success.
ISSN: 0029-8549

hal-01346933
https://hal-uvsq.archives-ouvertes.fr/hal-01346933
https://hal-uvsq.archives-ouvertes.fr/hal-01346933/document
https://hal-uvsq.archives-ouvertes.fr/hal-01346933/file/ms%20O%27Connor%20et%20al%20%202014%20%28Oecologia%29.pdf
PUBMED : 26080759

Éditeur(s) : HAL CCSD Oxford University Press (OUP): Policy B - Oxford Open Option A Oxford University Press (OUP)
Résumé : International audience
Peridotites exhumed in the footwall of axial detachment faults at slow-spreading ridges are highly serpentinized. Most mid-ocean ridge detachment settings are magmatically active and hydrous fluid circulation in and near the fault has been shown to be influenced by the presence of melt or magmatic lithologies. Our working area along the Southwest Indian Ridge (62–65°E) is nearly amagmatic and represents an end-member to study the hydrous alteration of exhumed peridotites without these magmatic influences. We use an integrated petrological approach combining microstructural, mineralogical and chemical observations to unravel the sequence of serpentinization in 272 dredged samples of variably serpentinized peridotites and to document the circulation of serpentinizing fluids in and near the exhumation faults. We find that serpentine recrystallization and veins overprint the initial serpentinite mesh texture in ∼25% of the samples. Oxygen isotope data suggest that this sequence developed at relatively high temperatures (271–336°C) and under increasing fluid–rock ratios, from near stoichiometry for mesh texture formation to >10 during recrystallization. Increasing fluid supersaturation relative to serpentine favors the replacement of mesh texture lizardite by chrysotile and polygonal or polyhedral serpentine. We attribute local recrystallization into antigorite to moderate Si-metasomatism, possibly following pyroxene serpentinization. We do not observe the more pronounced Si-metasomatism leading to talc replacing serpentine that is reported for the more magmatically active Mid-Atlantic Ridge detachment settings and is attributed to prior leaching of magmatic rocks. Scales of preferential fluid pathways in our samples evolved from pervasive and close-spaced (<500 µm) microfractures during the formation of the initial serpentine mesh texture, to centimeter-thick planar domains of enhanced fluid flux, spaced at ∼10 cm intervals and probably grouped in corridors that may be up to ∼100 m across. Serpentine minerals are enriched in some fluid-mobile elements (Cl, B, U) relative to the peridotite protolith, and several elements (Al, Fe, Si, Cu, As, Sb, REE) are redistributed at the millimeter to decimeter scale. Serpentinizing fluids were seawater-derived, probably mildly alkaline (small to no europium anomalies), reducing and H2-enriched (formation of magnetite). These fluids may have been similar to, though warmer than, those venting at the ultramafic-hosted Lost City hydrothermal fluid (30°N, Mid-Atlantic Ridge).
ISSN: 0022-3530

hal-01174047
https://hal.archives-ouvertes.fr/hal-01174047
DOI : 10.1093/petrology/egv014

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Whole-rock concentrations of Se and Te were determined in 53 peridotite samples collected in orogenic bodies from the Eastern Pyrenees, including the Lherz massif (33 samples), the type-locality of Iherzolite. Orogenic Iherzolites tectonically emplaced into the continental crust escaped devolatilisation that may strongly alter concentrations of those volatile trace elements in basalt-hosted peridotite xenoliths. The Se and Te concentration ranges (<3.5-100.7 ppb; <1-11 ppb) are consistent with the few analyses of mantle samples yet available, yet extending to higher Se concentrations. In-situ analyses performed by LAM-ICPMS on base metal sulfides indicate that the Se budget is controlled by sulfides whereas a large fraction of Te (50 +/- 30%) does not reside in sulfides. The missing fraction is accounted for by fractional crystallization of Pt-Pd tellurides from Cu-Ni sulfide melts. A maximum of one third of the S budget of Eastern Pyrenean peridotites was added by assimilation of crustal sulfides, which crystallized as pyrite. Disregarding those contaminated samples, some features of the Se and Te systematics (e.g. bivariate plots vs. fertility index) cannot be explained by partial melting processes. The best fit for 33 peridotites (mostly from Lherz) yields higher than chondritic S/Se (3.1213 +/- 500; r(2) = 0.96) for near chondritic Se/Te (8.6 +/- 2; r(2) = 0.9). Our study suggest that such superchondritic S/Se ratios are better explained by petrogenetic processes involving refertilization of harzburgitic lithosphere by metal (Cu,Ni)-rich sulfide melts precipitated along with clinopyroxene and Al-spinel from silicate melts en-route to the surface.
ISSN: 0009-2541

hal-00544577
https://hal.archives-ouvertes.fr/hal-00544577
DOI : 10.1016/j.chemgeo.2010.09.007

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The replenishment and persistence of marine species is contingent on dispersing larvae locating suitable habitatand surviving to a reproductive stage. Pelagic larvae rely on environmental cues to make behavioural decisionswith chemical information being important for habitat selection at settlement. We explored the sensory worldof crustaceans and fishes focusing on the impact anthropogenic alterations (ocean acidification, red soil, pesti-cide) have on conspecific chemical signals used by larvae for habitat selection. Crustacean (Stenopus hispidus)and fish (Chromis viridis) larvae recognized their conspecifics via chemical signals under control conditions. Inthe presence of acidified water, red soil or pesticide, the ability of larvae to chemically recognize conspecificcues was altered. Our study highlights that recruitment potential on coral reefs may decrease due to anthropo-genic stressors. If so, populations of fishes and crustaceans will continue their rapid decline; larval recruitmentwill not replace and sustain the adult populations on degraded reefs
ISSN: 0025-326X

hal-01491052
https://hal-univ-perp.archives-ouvertes.fr/hal-01491052
DOI : 10.1016/j.marpolbul.2016.08.083

Éditeur(s) : HAL CCSD Nature Publishing Group
Résumé : International audience
Polarization dependence second harmonic generation (P-SHG) microscopy is gaining increase popularity for in situ quantification of fibrillar protein architectures. In this report, we combine P-SHG microscopy, new linear least square (LLS) fitting and modeling to determine and convert the complex second-order non-linear optical anisotropy parameter ρ of several collagen rich tissues into a simple geometric organization of collagen fibrils. Modeling integrates a priori knowledge of polyhelical organization of collagen molecule polymers forming fibrils and bundles of fibrils as well as Poisson photonic shot noise of the detection system. The results, which accurately predict the known sub-microscopic hierarchical organization of collagen fibrils in several tissues, suggest that they can be subdivided into three classes according to their microscopic and macroscopic hierarchical organization of collagen fibrils. They also show, for the first time to our knowledge, intrahepatic spatial discrimination between genuine fibrotic and non-fibrotic vessels. CCl 4-treated livers are characterized by an increase in the percentage of fibrotic vessels and their remodeling involves peri-portal compaction and alignment of collagen fibrils that should contribute to portal hypertension. This integrated P-SHG image analysis method is a powerful tool that should open new avenue for the determination of pathophysiological and chemo-mechanical cues impacting collagen fibrils organization.
ISSN: 2045-2322

hal-01592192
https://hal.archives-ouvertes.fr/hal-01592192
https://hal.archives-ouvertes.fr/hal-01592192/document
https://hal.archives-ouvertes.fr/hal-01592192/file/s41598-017-12398-0.pdf
DOI : 10.1038/s41598-017-12398-0

Éditeur(s) : HAL CCSD Elsevier
Résumé : Handheld energy dispersive portable X-ray spectrometers (pXRF) are generally designed and used for qualitative survey applications. We developed shipboard quantitative analysis protocols for pXRF and employed the instrument to make over 2000 individual abundance measurements for a selection of major and trace elements on over 1200 m of recovered core during the eight weeks of the International Ocean Discovery Program (IODP) Expedition 352 to the Izu-Bonin forearc. pXRF analytical performance, accuracy and precision were found to be the same on powdered rock samples and on freshly cut rock surfaces, and sample results were similar within error to measurements made via shipboard ICP-OES analysis save at low abundance levels for a few elements. Instrument performance was optimal for elements between Z = 19 and Z = 40, and the system yielded reproducible data for K, Ca, Ti, V, Cr, Mn, Fe, Cu, Zn, Rb, Sr, and Zr on both powdered samples and rock surfaces. Working curves developed via pXRF measurement of a suite of geologic standard reference materials and well-characterized lavas permitted accurate quantitative measurements for many of the examined elements on both sample powders and rock surfaces. Although pXRF has been sporadically employed on previous cruises, Expedition 352 is the first time a detailed, high-density chemostratigraphy of recovered core samples was collected using pXRF measurements of rock core surfaces. These high-resolution data allowed the recognition of chemically distinct eruptive units in near real-time. The rapid identification of geochemical trends vastly improved our selection of samples for shipboard and shore-based analysis, permitted a more comprehensive interpretation of our Expedition results, and provided key decision-making information for drilling operations.
ISSN: 0009-2541

hal-01553188
https://hal.archives-ouvertes.fr/hal-01553188
DOI : 10.1016/j.chemgeo.2017.01.007

Éditeur(s) : HAL CCSD Springer Verlag/ASM International
Résumé : The use of zinc sheets has largely increased in the last years, fundamentally because of new tendencies in architecture and, at the same time, due to its excellent properties, as corrosion resistance under aggressive climatic conditions, malleability, recyclability, and surface finishing aspect. In the present work, the X-ray diffraction technique is used to characterize the crystallographic texture evolution of a strongly anisotropic Zn20 zinc sheet (Zn-Cu-Ti) subjected to uniaxial tension, plane strain, and equibiaxial tension, for specimens cut at 0, 45, and 90 deg with respect to the rolling direction. The crystallographic texture evolution is evaluated by means of pole figures, orientation distribution function, and Kearns factors. For all tested strain paths, deformation produces a decrease in the intensity of the crystallographic textures, due to a dispersion of the orientations of the different axes around the initial maxima.
ISSN: 1073-5623

hal-01583268
https://hal.archives-ouvertes.fr/hal-01583268
DOI : 10.1007/s11661-017-4069-y

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Because territoriality is energetically costly, territorial animals frequently respond less aggressively toneighbours than to strangers, a reaction known as the "dear enemy phenomenon" (DEP). The contrary,the "nasty neighbour effect" (NNE), occurs mainly for group-living species defending resource-basedterritories. We studied the relationships between supercolonies of the pest fire ant Solenopsis saevissimaand eight ant species able to live in the vicinity of its nests plus Eciton burchellii, an army ant predatorof other ants. The workers from all of the eight ant species behaved submissively when confrontedwith S. saevissima (dominant) individuals, whereas the contrary was never true. Yet, S. saevissima weresubmissive towards E. burchellii workers. Both DEP and NNE were observed for the eight ant species, withsubmissive behaviours less frequent in the case of DEP. To distinguish what is due to chemical cues fromwhat can be attributed to behaviour, we extracted cuticular compounds from all of the nine ant speciescompared and transferred them onto a number of S. saevissima workers that were then confronted withuntreated conspecifics. The cuticular compounds from three species, particularly E. burchellii, triggeredgreater aggressiveness by S. saevissima workers, while those from the other species did not.
ISSN: 0376-6357

hal-00913344
https://hal.archives-ouvertes.fr/hal-00913344
https://hal.archives-ouvertes.fr/hal-00913344/document
https://hal.archives-ouvertes.fr/hal-00913344/file/roux_10206.pdf
DOI : 10.1016/j.beproc.2013.04.014