Éditeur(s) : CRILLASH : Centre de Recherches Interdisciplinaires en Lettres, Langues, Arts et Sciences Humaines
Extrait de : "Tracées de Jean Bernabé" : colloque international, du 25 au 27 octobre 2017. Université des Antilles
Description : Cette communication reviendra sur un des romans de Jean Bernabé jusqu'ici peu exploité, titré de la géniale formule : Partage des ancêtres. Écrite dans le prolongement d'Éloge de la Créolité et portée par un souffle expérientiel, intellectuel et militant tonique, cette narration complexe découvre une série de personnages dont les histoires parallèles, entrecroisées, superposées, se décryptent petit à petit, par grattages successifs à la façon d'un véritable palimpseste. Que nous apprennent-elles ? Qu'à travers l'embrouillamini d'une geste familiale marquée par l'imprévisible, on ne peut se fier aux seules apparences phénotypiques. Au point qu'une blancheur physique et mentale peut être parfois bien plus foncée qu'on ne le pense, au même titre qu'une négritude peut bel et bien décacher de gros zestes de blanchitude ! Par quoi le véritable fil d'une dite « généalogie » désireuse de dépasser les quêtes d'identités-filiations aussi fantasmées que dangereusement essentialistes, ne peut être finalement suivi que dans la totale redécouverte, au dedans de soi-même, d'un nouvel état d'esprit ouvert aux genèses multiples et diverselles des appartenances, autrement dit se prêtant à partager ses ancêtres comme à en faire don.

Droits : CC-BY-NC-ND - Attribution - Pas d'utilisation commerciale - Pas de modification
Permalien : http://www.manioc.org/fichiers/V17228
V17228

Éditeur(s) : HAL CCSD IOS Press
Résumé : International audience
The hematocrit-to-viscosity ratio (HVR) has been widely used has an estimate of red blood cell (RBC) oxygen transport effectiveness into the microvasculature or as an oxygen delivery index. However, no study investigated the possibility of HVR to truly reflect RBC oxygen transport effectiveness or to be an oxygen delivery index. We measured blood viscosity at high shear rate (225 s-1), hematocrit, HVR, as well as the microvascular oxyhemoglobin saturation (TOI; tissue oxygen index) by spatial resolved near-infrared spectroscopy (NIRS) at cerebral and muscle levels in three population known to have various degrees of hemorheological abnormalities: healthy subjects (AA), patients with sickle cell SC disease (SC) characterized by moderate anemia and patients with sickle cell anemia (SS) marked by severe anemia. At both the cerebral and muscle level, HVR was positively correlated with TOI (r = 0.28; p = 0.03 and r = 0.38; p = 0.003, at the cerebral and muscle level, respectively). These findings suggest that HVR probably play a key role in blood flow and hemodynamic regulation in the microvasculature, hence modulating the amount of oxygen available for tissues. Nevertheless, the strengths of the associations are weak (R2 < 0.50), suggesting that other determinants modulate microvascular blood flow and oxygenation, such as vascular geometry and vasomotor reserve.
ISSN: 1386-0291

inserm-01081701
http://www.hal.inserm.fr/inserm-01081701
http://www.hal.inserm.fr/inserm-01081701/document
http://www.hal.inserm.fr/inserm-01081701/file/2013%2C%20Waltz%20-%20Is%20there%20a%20relationship%20between%20the%20hematocrit-to-viscosity%20ratio%20and%20microvascular%20oxygenation%20in%20brain%20and%20muscle.pdf
PUBMED : 23719422

Éditeur(s) : Gauthier-Villars
Résumé : Phosphorite genesis correlates in a general way with elevated sea level and warm climate and is therefore influenced by plate tectonics and continental drift. Phosphorite genesis correlates more specifically with transgression -- a result of the interaction of continental hypsometry, tectonic perturbation and eustatic effects -- whereby a small number of shallow slope and shelf sites are available for phosphate fixation. Phosphorite genesis correlates with warm climate. Oceanic anoxic events (OAE's : episodes of world-wide deposition and preservation of organic carbon), which also correlate with particularly high sea level stands, generally do not coincide with major phosphorogenic episodes. In contrast to the assertions above, the permian Phosphoria Fromation was deposited during a marked overall global low-stand of sea level. However, the phosphatic sequences were laid down during brief transgressive episodes.
Oceanologica Acta, Special issue (0399-1784) (Gauthier-Villars), 1981

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00245/35660/34169.pdf
http://archimer.ifremer.fr/doc/00245/35660/

Éditeur(s) : HAL CCSD
Résumé : Volatile-rich, silica-undersaturated alkaline lavas record the important role of fluids during fluid-rock and magma-rock interactions in the mantle, which are key processes to understand the dynamics of the convective mantle and lithosphere-asthenosphere interactions in intracontinental settings. The aim of this thesis is to bring new constraints on the genesis of alkaline magmas by characterizing the crystallization conditions, the source and the partial melting processes taking part in the genesis of olivine nephelinites, pyroxene nephelinites and basanites from the Jbel Saghro volcanic field in the Moroccan Anti Atlas.The petrological and geochemical study of rocks and minerals coupled with the analysis of fluid inclusions constrains the pre-eruptive conditions of Saghro nephelinites to 1.7–2.2 GPa and ~1350 °C. Minerals show that nephelinitic magmas are rich in volatile elements (Cl, F, S), and fluid inclusions indicate that magmas were saturated with a CO2-rich fluid at pressures > 590 MPa. The various mineralogical assemblages and the presence of peridotite xenoliths suggest a rapid ascent for olivine nephelinites and more complex processes at depth for pyroxene nephelinites.Fractional crystallization and partial melting modelling of Saghro mafic lavas indicate that they are low-degree melts (0.6–2.5 %) of an amphibole-bearing carbonated peridotite enriched in incompatible elements, at the garnet-spinel transition (~80–85 km). Saghro nephelinites display a temporal evolution with a slight increase of the degree of melting and a decrease of the amount of residual amphibole from the oldest (olivine nephelinites, 9.6 Ma) to the most recent (pyroxene nephelinites, 2.9 Ma). Basanites form a system that is independent from nephelinites and are slightly higher-degree melts. Important variations in their chemical composition suggest variable amounts of fractional crystallization during ascent.The peculiar characteristics of Saghro nephelinites and basanites (enrichment in incompatible elements, negative anomalies in K, Zr, Hf and Ti, high Ca/Al and Zr/Hf ratios) indicate that their source was affected by carbonatitic metasomatism. The influence of this metasomatism is stronger for pyroxene nephelinites than for olivine nephelinites. These results suggest fluid-rock interactions beneath the Northwest African Craton, leading to the formation of a metasomatized mantle by CO2-rich carbonatitic components at the lithosphere-asthenosphere transition. The origin of the metasomatism inducing source enrichment and the formation of amphibole veins could be attributed to the melting of relict subducted oceanic lithosphere. The relatively low melting temperatures (< 1350 °C) suggest the absence of a thermal anomaly beneath the Jbel Saghro, and thus support a lithosphere delamination model as precursor of Saghro volca0,3nism. However, the increasing degree of partial melting over time, also observed in the Middle Atlas, together with the isotopic and geochemical similarities with Canary Islands alkaline lavas does not allow us to discard the influence of a deviation of the Canary mantle plume beneath northwest Africa.
Les laves alcalines sous-saturées riches en éléments volatils sont les marqueurs du rôle important des fluides dans le manteau et des interactions fluide-roche et magma-roche, processus clés pour comprendre la dynamique du manteau convectif et les interactions asthénosphère-lithosphère en domaine intracontinental. L’objectif de cette thèse est d’apporter de nouvelles contraintes sur la genèse des magmas alcalins en caractérisant les conditions de cristallisation, la source et les processus de fusion partielle à l’origine des néphélinites à olivine, des néphélinites à pyroxène et des basanites du champ volcanique du Jbel Saghro dans l’Anti-Atlas marocain.L’étude pétrologique et géochimique des roches et des minéraux, couplée à l’analyse des inclusions fluides a permis de contraindre les conditions pré-éruptives des néphélinites de Saghro à 1.7–2.2 GPa et ~1350 °C. Les minéraux montrent que les magmas néphélinitiques sont riches en éléments volatils (Cl, F, S), et les inclusions fluides indiquent que les magmas étaient saturés en fluide riche en CO2 à des pressions > 590 MPa. Les différents assemblages minéralogiques des néphélinites et la présence de xénolites péridotitiques suggèrent une ascension rapide des néphélinites à olivine et des processus plus complexes en profondeur pour les néphélinites à pyroxène.La modélisation des processus de cristallisation fractionnée et de fusion partielle des laves mafiques de Saghro a permis de déterminer qu’elles sont issues de faibles taux de fusion partielle (0.6–2.5 %) d’une péridotite carbonatée enrichie en éléments incompatibles, au niveau de la transition grenat–spinelle (~80–85 km) et en présence d’amphibole. Les néphélinites de Saghro montrent une évolution temporelle avec une légère augmentation du taux de fusion et une diminution de la quantité d’amphibole au résidu des plus anciennes (néphélinites à olivine, 9.6 Ma) aux plus récentes (néphélinites à pyroxène, 2.9 Ma). Les basanites forment un système indépendant des néphélinites et sont issues de taux de fusion plus élevés. Les fortes variations dans leur composition chimique suggèrent qu’elles ont subi de la cristallisation fractionnée lors de leur ascension.Les caractéristiques particulières des néphélinites et basanites de Saghro (enrichissement en éléments incompatibles, anomalies négatives en K, Zr, Hf et Ti, rapports Ca/Al et Zr/Hf élevés) indiquent que leur source a subi un métasomatisme principalement carbonatitique. L’influence de ce métasomatisme est plus forte pour les néphélinites à pyroxène que pour les néphélinites à olivine, impliquant une évolution temporelle de l’intensité du métasomatisme. Ces résultats suggèrent des interactions fluide-roche sous le craton Nord-Ouest Africain, entraînant la formation d'un manteau métasomatisé par des composants carbonatitiques riches en CO2 au niveau de la transition lithosphère-asthénosphère. L’origine du métasomatisme provoquant l’enrichissement de la source et la formation de veines d’amphibole pourrait être liée à la fusion de reliquats de croûte océanique subductée. Les températures de fusion relativement faibles (< 1350 °C) suggèrent l’absence d’anomalie thermique sous le Jbel Saghro, et favorisent donc un modèle de délamination de la lithosphère comme initiateur du volcanisme. Cependant, l’augmentation du taux de fusion partielle au cours du temps, également observée dans le Moyen Atlas, et les similitudes isotopiques et géochimiques avec les laves alcalines des îles Canaries ne permettent pas d’exclure une influence du panache des Canaries sur la source du volcanisme alcalin du Jbel Saghro.
https://tel.archives-ouvertes.fr/tel-01615888

NNT : 2015MONTS070
tel-01615888
https://tel.archives-ouvertes.fr/tel-01615888
https://tel.archives-ouvertes.fr/tel-01615888/document
https://tel.archives-ouvertes.fr/tel-01615888/file/53752_CHAMBOREDON_2015_archivage_cor.pdf

Éditeur(s) : HAL CCSD
Résumé : International audience
The functioning of the Manche-à-Eau lagoon and of its mangrove environment with the population of marine fish of Guadeloupe has been studied since 1983, and particularly in the 2000s. This ecosystem supports a stable fish assemblage structure because of its twice a day turnover (14.8%) of marine water. It is a favorable and important site for the reproduction (38%) and growth (46%) of a large number of species. The life cycle of these fish species share, for the most part, an ecophase in the mangrove in brackish water and a marine ecophase outside the lagoon. The mangrove plays a vital role in the retention of continental nutrients. This facilitates the trophic exploitation of vegetal and animal detritus bases by the fish in high population density. The majority of populations present individuals reaching length at least 40% from the known maximum length for the species, although only 38.1% have individuals longer than 300 mm. The mangrove aids in the spawning activity of fish species (41% to 58% of the total abundance) and in the reproductive (maturation, migration) process (58% in density and 70% in biomass). The sedentary species lay their eggs in the mangrove, whereas the temporary species stay there during their trophic ecophase or after a genesic migration from the sea to assure sexual maturation for both sexes in the species.
Proceedings of the 61st Gulf and Caribbean Fisheries Institute
Gosier, Guadeloupe

hal-00755780
https://hal.univ-antilles.fr/hal-00755780
https://hal.univ-antilles.fr/hal-00755780/document
https://hal.univ-antilles.fr/hal-00755780/file/GCFI_61_2009_307-312.pdf

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Patients with sickle cell anemia (SCA) have usually lower diastolic, systolic and mean blood pressure (BP) than the general population. However, BP values ≥120/70 mmHg considerably increase the risk for acute and chronic complications in SCA. The aim of this study was to identify biological factors associated with relative hypertension in adults with SCA. We compared the hematological, lipid and hemolytic profiles, as well as blood viscosity, between SCA patients with normal BP (<120/70 mmHg, n = 54) and those with relative hypertension (BP≥120/70 mmHg, n = 43). Our results demonstrated that male gender (OR: 3.49; 95%CI 1.20 to 10.16, p<0.05), triglycerides (OR: 9.19; 95% CI 2.29 to 36.95, p<0.01), blood viscosity (OR: 1.35; 95% CI 1.01 to 1.81, p<0.05) and body mass index (OR: 1.37; 95% CI 1.14 to 1.64, p<0.01) were independent risks factors for relative hypertension in SCA. No association was found between the BP status and the positive history of painful vaso-occlusive crisis or acute chest syndrome. An association between triglycerides level and the occurrence of these two major acute complications was detected. Our study suggests that male gender, increased triglycerides level, BMI and blood viscosity could increase the risk for developing relative hypertension in SCA. In addition, our results support a role of moderately elevated triglycerides in the pathophysiology of vaso-occlusive events.
ISSN: 1932-6203

inserm-00838991
http://www.hal.inserm.fr/inserm-00838991
http://www.hal.inserm.fr/inserm-00838991/document
http://www.hal.inserm.fr/inserm-00838991/file/Lamarre_et_al._2013_PloS_ONE_.pdf
DOI : 10.1371/journal.pone.0066004

Éditeur(s) : HAL CCSD American Geophysical Union (AGU)
Résumé : International audience
[1] Zircons and monazites from 6 samples of the North Ayilari dextral shear zone (NAsz), part of the Karakorum fault zone (KFZ), have been dated with the U-Th-Pb method, using both ID-TIMS and SIMS techniques. The ages reveal (1) inheritance from several events spanning a long period between the late Archean and the Jurassic; (2) an Eocene-Oligocene magmatic event (similar to 35-32 Ma); (3) an Oligo-Miocene magmatic event (similar to 25-22 Ma), at least partly synkinematic to the right-lateral deformation; and (4) a period of metamorphism metasomatism (similar to 22-14 Ma) interpreted as thermal and fluid advection in the shear zone. The Labhar Kangri granite located similar to 375 km farther Southeast along the KFZ is dated at 21.1 +/- 0.3 Ma. Such occurrence of several Oligo-Miocene granites along the KFZ, some of which show evidence for synkinematic emplacement, suggests that the fault zone played an important role in the genesis and /or collection of crustal melts. We discuss several scenarios for the onset and propagation of the KFZ, and offset estimates based on the main sutures zones. Our preferred scenario is an Oligo-Miocene initiation of the fault close to the NA range, and propagation along most of its length prior to similar to 19 Ma. In its southern half, the averaged long-term fault-rate of the KFZ is greater than 8 to 10 mm/a, in good agreement with some shorter-term estimates based on the Indus river course, or Quaternary moraines and geodesy. Our results show the KFZ cannot be considered as a small transient fault but played a major role in the collision history.
ISSN: 0278-7407

hal-00412570
https://hal.archives-ouvertes.fr/hal-00412570
DOI : 10.1029/2007TC002184

Éditeur(s) : HAL CCSD IOS Press
Résumé : International audience
The hematocrit-to-viscosity ratio (HVR) has been widely used has an estimate of red blood cell (RBC) oxygen transport effectiveness into the microvasculature or as an oxygen delivery index. However, no study investigated the possibility of HVR to truly reflect RBC oxygen transport effectiveness or to be an oxygen delivery index. We measured blood viscosity at high shear rate (225 s −1), hematocrit, HVR, as well as the microvascular oxyhemoglobin saturation (TOI; tissue oxygen index) by spatial resolved near-infrared spectroscopy (NIRS) at cerebral and muscle levels in three population known to have various degrees of hemorheological abnormalities: healthy subjects (AA), patients with sickle cell SC disease (SC) characterized by moderate anemia and patients with sickle cell anemia (SS) marked by severe anemia. At both the cerebral and muscle level, HVR was positively correlated with TOI (r = 0.28; p = 0.03 and r = 0.38; p = 0.003, at the cerebral and muscle level, respectively). These findings suggest that HVR probably play a key role in blood flow and hemodynamic regulation in the microvasculature, hence modulating the amount of oxygen available for tissues. Nevertheless, the strengths of the associations are weak (R 2 < 0.50), suggesting that other determinants modulate microvascular blood flow and oxygenation, such as vascular geometry and vasomotor reserve.
ISSN: 1386-0291

hal-01163460
https://hal.univ-antilles.fr/hal-01163460
DOI : 10.3233/CH-131742

Éditeur(s) : Elsevier Science Bv
Résumé : Here we present a new geochemical study of Lopevi volcano, one the most active volcanoes in the Vanuatu island arc. We focus on the temporally well-defined sequence of lava flows emitted since 1960, and for the first time, on pre-1960 volcanic products, including high-MgO basalts and felsic andesites, the most evolved lavas sampled so far on this island. This work reports the first Pb and Hf isotopic study of lavas from Lopevi island. These lavas display correlations between differentiation indexes such as SiO2 content and isotopic ratios. The felsic andesites extend the known correlations with both the least (Sr-Pb) and the most (Nd-Hf) radiogenic isotopic compositions on the island. Our results confirm that the rising magma interacted with the sub-arc crust. Assimilation-Fractional Crystallization (AFC) quantitative modeling of trace element ratios and isotopic compositions requires 1% and 10% of assimilated partial melts of a mafic oceanic crust to account for the pre- and post-1960 lavas, respectively. The post-1960 lavas differ from the former lavas emitted similar to 20 years earlier by enrichments in fluid mobile elements (K, Ba, Rb ... ), Th, and Light Rare Earth Elements (LREE). We ascribe these features to slight variations in the metasomatic agent added to the sub-arc mantle and ultimately derived from the subducted lithosphere. However, the contrasting time scales involved in subducted lithosphere dehydration and magma genesis, relative to the time elapsed between eruptions of the two lava series, suggest that two different portions of mantle which have undergone slightly different metasomatism, gave birth to the Lopevi lavas. These distinct magmas are still present beneath the volcano.
Journal Of Volcanology And Geothermal Research (0377-0273) (Elsevier Science Bv), 2013-08 , Vol. 264 , P. 72-84

Droits : 2013 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/00167/27801/26223.pdf
DOI:10.1016/j.jvolgeores.2013.07.005
http://archimer.ifremer.fr/doc/00167/27801/

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
: In non-mammalian vertebrates, serotonin (5-HT)-producing neurons exist in the paraventricular organ (PVO), a diencephalic structure containing cerebrospinal fluid (CSF)-contacting neurons exhibiting 5-HT or dopamine (DA) immunoreactivity. Because the brain of the adult teleost is known for its neurogenic activity supported, for a large part, by radial glial progenitors, this study addresses the origin of newborn 5-HT neurons in the hypothalamus of adult zebrafish. In this species, the PVO exhibits numerous radial glial cells (RGCs) whose somata are located at a certain distance from the ventricle. To study relationships between RGCs and 5-HT CSF-contacting neurons, we performed 5-HT immunohistochemistry in transgenic tg(cyp19a1b-GFP) zebrafish in which RGCs are labelled with GFP under the control of the cyp19a1b promoter. We show that the somata of the 5-HT neurons are located closer to the ventricle than those of RGCs. RGCs extend towards the ventricle cytoplasmic processes that form a continuous barrier along the ventricular surface. In turn, 5-HT neurons contact the CSF via processes that cross this barrier through small pores. Further experiments using proliferating cell nuclear antigen or 5-bromo-2'-deoxyuridine indicate that RGCs proliferate and give birth to 5-HT neurons migrating centripetally instead of centrifugally as in other brain regions. Furthermore, treatment of adult zebrafish with tryptophan hydroxylase inhibitor causes a significant decrease in the number of proliferating cells in the PVO, but not in the mediobasal hypothalamus. These data point to the PVO as an intriguing region in which 5-HT appears to promote genesis of 5-HT neurons that accumulate along the brain ventricles and contact the CSF.
ISSN: 0953-816X

inserm-00866212
http://www.hal.inserm.fr/inserm-00866212
DOI : 10.1111/ejn.12348
PUBMED : 23981075

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The eastern part of the Cordillera Occidental of Ecuador comprises thick buoyant oceanic plateaus associated with island-arc tholeiites and subduction-related calc-alkaline series, accreted to the Ecuadorian Continental Margin from Late Cretaceous to Eocene times. One of these plateau sequences, the Guaranda Oceanic Plateau is considered as remnant of the Caribbean–Colombian Oceanic Province (CCOP) accreted to the Ecuadorian Margin in the Maastrichtien. Samples studied in this paper were taken from four cross-sections through two arc-sequences in the northern part of the Cordillera Occidental of Ecuador, dated as (Río Cala) or ascribed to (Macuchi) the Late Cretaceous and one arc-like sequence in the Chogòn-Colonche Cordillera (Las Orquídeas). These three island-arcs can clearly be identified and rest conformably on the CCOP. In all four localities, basalts with abundant large clinopyroxene phenocrysts can be found, mimicking a picritic or ankaramitic facies. This mineralogical particularity, although not uncommon in island arc lavas, hints at a contribution of the CCOP in the genesis of these island arc rocks. The complete petrological and geochemical study of these rocks reveals that some have a primitive island-arc nature (MgO values range from 6 to 11 wt.%). Studied samples display marked Nb, Ta and Ti negative anomalies relative to the adjacent elements in the spidergrams characteristic of subduction-related magmatism. These rocks are LREE-enriched and their clinopyroxenes show a tholeiitic affinity (FeOT–TiO2 enrichment and CaO depletion from core to rim within a single crystal). The four sampled cross-sections through the island-arc sequences display homogeneous initial Nd, and Pb isotope ratios that suggest a unique mantellic source for these rocks resulting from the mixing of three components: an East-Pacific MORB end-member, an enriched pelagic sediment component, and a HIMU component carried by the CCOP. Indeed, the ankaramite and Mg-basalt sequences that form part of the Caribbean-Colombian Oceanic Plateau are radiogenically enriched in 206Pb/204Pb and 207Pb/204Pb and contain a HIMU component similar to that observed in the Gorgona basalts and Galápagos lavas. The subduction zone that generated the Late Cretaceous arcs occurred far from the continental margin, in an oceanic environment. This implies that no terrigenous detrital sediments interacted with the source at this period. Thus, the enriched component can only result from the melting of subducted pelagic sediments. We have thus defined the East-Pacific MORB, enriched (cherts, pelagic sediments) and HIMU components in an attempt to constrain and model the genesis of the studied island-arc magmatism, using a compilation of carefully selected isotopic data from literature according to rock age and paleogeographic location at the time of arc edification. Tripolar mixing models reveal that proportions of 12–15 wt.% of the HIMU component, 7–15 wt.% of the pelagic sediment end-member and 70–75 wt.% of an East-pacific MORB end-member are needed to explain the measured isotope ratios. These surprisingly high proportions of the HIMU/CCOP component could be explained by the young age of the oceanic plateau (5–15 Ma) during the Late Cretaceous arc emplacement. The CCOP, basement of these arc sequences, was probably still hot and easily assimilated at the island-arc lava source.
ISSN: 0895-9811

insu-00353692
https://hal-insu.archives-ouvertes.fr/insu-00353692
DOI : 10.1016/j.jsames.2008.06.003

Éditeur(s) : HAL CCSD Springer Verlag (Germany) Springer Verlag
Résumé : International audience
We report here U-series and trace element data for an olivine-melilitite lava flow, erupted in 1957 in the Virunga volcanic field and known as the Mugogo eruption. Petrological and geochemical data show that the Mugogo magma represents a primary mantle melt, derived from a low degree of melting of a metasomatised mantle source. It is highly enriched in very incompatible trace elements (e.g. more than 300-fold compared to primitive mantle for Th), with a distinctly lower enrichment in Rb, Ba and Sr. The high Th/U and low (230Th/232Th) ratios (4.4 and 0.750, respectively, with a (230Th/238U) ratio of 1.09) are close to the values found for the Nyamuragira basanites. But the most striking feature is the very low (226Ra/230Th) ratio of 0.48, the lowest ever measured in a mafic volcanic rock. The most probable origin of this Ra deficit is the presence of phlogopite (having a high Ra partition coefficient) in the lithospheric mantle, either as a residual phase during low-degree isobaric melting (in batch-melting or a diffusion-controlled melting models), or in a phlogopite-bearing upper mantle through which the melt migrates and equilibrates (in an equilibrium porous flow model commonly used to describe adiabatic melting). The disequilibrium pattern (230Th) > (238U) > (210Pb) ≫ (226Ra), reversed compared to the pattern observed in the Oldoinyo Lengai natrocarbonatite, suggests that a carbonatite melt might have been involved to explain the Ra deficit. We thus discuss the possibility of an early separation of a Ra-enriched carbonate melt either from the olivine-melilitite melt or from a carbonated mantle source, followed by the production of a low-degree melt of olivine-melilitite composition, but the lack of available experimental, petrological and geochemical evidences makes this process somewhat speculative at present. Further studies of recent (<5 ky) olivine-melilitites are needed to check whether the large Ra deficit is a general characteristic of this type of magma that can be used to constrain models of its formation.
ISSN: 0010-7999

hal-01174173
https://hal.archives-ouvertes.fr/hal-01174173
DOI : 10.1007/s00410-015-1124-9

Éditeur(s) : Elsevier Science Bv
Résumé : The opening of the Equatorial and South Atlantic Oceans is still a matter of debate, particularly as concerns the locations of the intraplate deformation. We propose here a critical review of the kinematic models published since Bullard et al., 1965, based on a series of constraints: new interpretation of the magnetic anomalies, seafloor isochrons, flow lines, fracture zones, continental and oceanic homologous structures and radiometric dating of igneous rocks. All of these models present numerous unexplained misfits (gaps, overlaps and misalignments). We present here a new evolution of the Equatorial and South Atlantic Ocean from the tightest reconstruction to Chron C34. This new model confirms the hypothesis of a northward propagation of the South American deformation proposed by Eagles, but rejuvenates slightly the ages for this propagation and refines the plate reconstructions. In particular, we highlight the role of the kinematic "buffer" Santos block, located between the salty Aptian Central segment in the North and the Volcanic Hauterivian Austral segment in the South. The new initial fit presented in this study represents the tightest reconstruction that could be obtained and constitutes the base canvas on which the problem of the continental margin genesis should be addressed.
Earth Science Reviews (0012-8252) (Elsevier Science Bv), 2010 , Vol. 98 , N. 1-2 , P. 1-37

Droits : 2010 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/00000/11160/7883.pdf
DOI:10.1016/j.earscirev.2009.08.001
http://archimer.ifremer.fr/doc/00000/11160/

Résumé : Deep-sea drilling project, launched by the U.S.A. in 1964, aiming to better understand the conditions of genesis and evolution of the ocean. The first drilling was carried out by the "Glomar Challenger" in the Gulf of Mexico in 1968. From 1968 to 1981, more than 600 sites have been drilled during 80 cruises conducted on board the "Glomar Challenger". The international phase or fourth phase of the D.S.D.P. started in 1975 and ended in 1981. Five countries joined the U.S. in this project: the U.S.S.R, Federal Germany, Japan, England and France. The P.O.D. focus: Drilling the oceanic bottoms deeper than during the first three phases of the D.S.D.P.
Projet de forage des grands fonds océaniques, lancé par les États-Unis en 1964, dans le but de mieux comprendre les conditions de genèse et d'évolution de l'océan. Premier forage effectué par le "Glomar Challenger" dans le Golfe du Mexique en 1968. De 1968 à 1981, plus de 600 sites ont été forés au cours de 80 campagnes du "Glomar Challenger". La phase internationale ou quatrième phase du DSDP, qui a débuté en 1975, s'achève en 1981. Cinq pays étrangers se sont joints aux États-Unis pour réaliser ce projet : l'URSS, l'Allemagne Fédérale, le Japon, l'Angleterre et la France. Les objectifs dflPOD : forer plus profondément les fonds océaniques qu'au cours des trois premières phases du DSDP. [OCR NON CONTRÔLE]

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/1981/rapport-4941.PDF
http://archimer.ifremer.fr/doc/00000/4941/

Éditeur(s) : HAL CCSD Taylor & Francis
Résumé : Modern geochronology has moved beyond the acquisition of dates: the goal is to understand the significance of these numbers for the geodynamic evolution of Earth at all scales. The coupling of the laser-ablation microprobe (LAM) to inductively coupled plasma mass spectrometers (ICPMS, multicollector (MC)-ICPMS) has revolutionised geochronology and geochemistry over the last 10 years. These systems enable the rapid and precise in situ analysis of trace-element patterns and isotopic systems, while adding information related to microstructural context and major-element composition. The integration of these multiple sources of data is crucial in constraining the origin of the sample and the processes leading to its formation, so that we can understand the meaning of a date in terms of geological events. LAM-ICPMS measurement of U-Pb ages and trace-element patterns in zircon, coupled with LAM-MC-ICPMS analysis of Hf isotopes in the same grains, gives new insights into the processes of magma genesis. Applied to detrital zircons from modern drainages or sedimentary rocks (the TerraneChron approach), it becomes a powerful tool to investigate problems of crustal evolution on scales ranging from single terranes to continents. The in situ analysis (LAM-MC-ICPMS) of Re-Os systematics in single grains of sulfides in mantle-derived peridotites has demonstrated that most mantle rocks contain several generations of Os-bearing sulfides; whole-rock analyses are mixtures reflecting multiple melting and metasomatic events in the lithospheric mantle. These deep-seated events are commonly mirrored in the crust; Os model-age spectra from xenolith suites show age 'peaks' that correspond to the ages of thermal/tectonic events in the overlying crust, suggesting strong linkages between crust and mantle. Integrated studies of the timing and nature of crustal and mantle events, using these techniques, will be important for understanding the large-scale dynamics of the Earth.
ISSN: 0812-0099

hal-00411328
https://hal.archives-ouvertes.fr/hal-00411328
DOI : 10.1080/08120090802097450

Éditeur(s) : HAL CCSD AGU and the Geochemical Society
Résumé : Mid-ocean ridges magmatism is, by and large, considered to be mostly dry. Nevertheless, numerous works in the last decade have shown that a hydrous component is likely to be involved in ocean ridges magmas genesis and/or evolution. The petrology and geochemistry of peculiar coarse grained gabbros sampled in the upper part of the gabbroic sequence from the northern Oman ophiolite (Wadi Rajmi) provide information on the origin and fate of hydrous melts in fast-spreading oceanic settings. Uncommon crystallization sequences for oceanic settings (clinopyroxene crystallizing before plagioclase), extreme mineral compositions (plagioclase An% up to 99, and clinopyroxene Mg # up to 96), and the presence of magmatic amphibole, imply the presence of a high water activity during crystallization. Various petrological and geochemical constraints point to hydration, resulting from the recycling of hydrothermal fluids. This recycling event may have occurred at the top of the axial magma chamber where assimilation of anatectic hydrous melts is recurrent along mid-ocean ridges or close to segments ends where fresh magma intrudes previously hydrothermally altered crust. In ophiolitic settings, hydration and remelting of hydrothermally altered rocks producing hydrous melts may also occur during the obduction process. Although dry magmatism dominates oceanic magmatism, the dynamic behavior of fast-spreading ocean ridge magma chambers has the potential to produce the observed hydrous melts (either in ophiolites or at spreading centers), which are thus part of the general mid-ocean ridges lineage.
ISSN: 1525-2027

hal-00939400
https://hal.archives-ouvertes.fr/hal-00939400
DOI : 10.1002/ggge.20137

Éditeur(s) : The Geological Society of London
Résumé : Conservational models, like simple shear, pure shear or polyphase models that exclude exchanges between the lower continental crust and upper mantle, are usually proposed to explain the lithospheric stretching and consequent crustal thinning of passive continental margins. These models need large amounts of horizontal movement, and have, therefore, important implications for plate kinematic reconstructions and intraplate deformation. In this paper we propose to show these implications in the Central Segment of the South Atlantic Ocean. In the Angola–Brazilian system, these models imply about 240 km of horizontal movement. This movement can be compensated by two end-member mechanisms: (1) an intraplate deformation located in Africa; and (2) an intraplate deformation located in South America. We detail for each solution the strong geological and geodynamical implications, and discuss the consequences for the genesis of passive continental margins.
Geological Society, special publication (0375-6440) (The Geological Society of London), 2012-02 , Vol. 369 , P. 75-90

Droits : The Geological Society of London 2012
http://archimer.ifremer.fr/doc/00087/19839/17757.pdf
DOI:10.1144/SP369.5
http://archimer.ifremer.fr/doc/00087/19839/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The Madeira Sn-Nb-Ta deposit corresponds to the albite-enriched facies of Madeira granite (Madeira Suite) that is part of a NE-SW alignment of three granitic bodies. Structural analyses suggest that the albite-enriched granite emplacement and development of related structures occurred in a different tectonic setting than earlier facies of the granitic bodies in the NE-SW alignment and that the structure was dominated by a N-NE-trending shortening related to a left-lateral motion along a NE-SW corridor within a Riedel shear. Three types of structures (flat-lying, near vertical fractures, and geodes/miaroles) concentrated the last magmatic-related fluid in the albite-enriched granite. U-Pb in situ zircon dating of the albite-enriched granite yielded an age of 1,822 ± 22 Ma. The other granitic plutons of the Madeira Suite, Água Boa granite (topaz-granite facies), and Europa per-alkaline granite formed at 1,825 ± 14 Ma, 1,831± 11 Ma, and 1,839 ± 10 Ma, respectively. The granite bodies of the Madeira Suite occur in an area occupied by a cauldron complex composed of volcanic sequences (Iricoumé Group) and associated A-type granites (Mapuera Suite), and their formation was controlled by the reactivation of the cauldron structures and the pre-existing structures. The gap between the cauldron complex and the Madeira Suite is no greater than 35 Ma. The geological evolution was reanalyzed from the perspective of an entire extensional environment where three successive episodes of A-type magmatism and basin formation (Urupi Formation) occurred. The data and interpretations of this work imply crucial constraints on the petrologic models proposed for the albite-enriched granite and, consequently, on the genesis of the Madeira deposit
ISSN: 0301-9268

insu-00939888
https://hal-insu.archives-ouvertes.fr/insu-00939888
https://hal-insu.archives-ouvertes.fr/insu-00939888/document
https://hal-insu.archives-ouvertes.fr/insu-00939888/file/BastosNeto-PrecambrianResearch-2014.pdf
DOI : 10.1016/j.precamres.2013.12.021

Éditeur(s) : HAL CCSD
Résumé :  
The main aspects of wood mechanics are approached through the role played by wood as the building material of the tree. The main concepts used by nature: progressive setting up of tree weight and architecture, multifunctional role of wood and adaptability to hazard and long-term evolution, are clarified together with their consequence on the multilayered, anisotropic nature of wood. The technological choices of the plant world as the cellular structure, the use of composite with oriented fibres and hydro-carbonated polymers, as well as the systematic prestressing of every new layer, bear obvious consequences on the type of mechanical behaviour of wood. The local control of the level of prestressing through minor modifications of the cell-wall biosynthesis allows the tree to adapt to conditions of light exploration that will evolve according to time and risk occurrence. This analysis of wood genesis process permits in return to improve our understanding of the mechanical behaviour of the material in relation with the parameters of the microstructure.
Comptes Rendus de l'Académie des Sciences Série 2

hal-01032151
https://hal.archives-ouvertes.fr/hal-01032151
DOI : 10.1016/S1620-7742(01)01380-0

Résumé : On August 18th, 1967, H.M. Arvid Pardo, Malta's delegate at the UN, referred to the General Assembly with the question entitled: "Examination of the question of the reservation exclusively for peaceful purposes of the sea-bed and the ocean floor, and the subsoil thereof, underlying the high seas beyond the limits of present national jurisdiction, and the use of their resources in the interests of mankind." (1) This proposal was not the result of pure abstract thinking, but was, on the contrary, the wording of the necessity to adapt marine legislation to the current development state of the international society. However, this evolutive perspective does not exist only economically and technically speaking: it develops in the political field, especially in the development of the nations claim over marine spaces and the genesis of the principle of freedom of high seas. As in any dialectical perspective, legislation interferes with these de facto situations and imposes a number of directions to the study of a legal regime responding to the needs of a changing international society.
Le 18 août 1967, SE Arvid PARDO, représentant de Malte à l'ONU, saisit l'Assemblée Générale de la question intitulée : "Examen de la question de l'affectation à des fins exclusivement pacifiques du lit des mers ainsi que de leur sous sol, au-delà des limites de la juridiction nationale actuelle et de l'exploitation de leurs ressources dans l'intérêt de l'humanité". (1) Cette proposition n'était pas l'émanation d'une réflexion purement abstraite, mais traduisait au contraire la nécessité d'adapter le droit de la mer à l'état de développement de la société internationale. Cependant, cette perspective évolutive n'existe pas seulement sur le plan économique et technologique : elle se développe au niveau politique, particulièrement dans l'extension des prétentions étatiques sur les espaces maritimes et la genèse du principe de liberté de la haute mer. Comme dans toute perspective dialectique, le droit interfère sur ces situations de fait et impose donc a priori certaines orientations à l'étude d'un régime juridique répondant aux besoins d'une société internationale en pleine mutation. [OCR NON CONTRÔLE]

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/1973/rapport-4803.PDF
http://archimer.ifremer.fr/doc/00000/4803/