Manioc : Portail | resultats 161 - 180 pour la recherche: gas composition

Partial characterization of an exopolysaccharide secreted by a marine bacterium, Vibrio neocaledonicus sp nov., from New Caledonia
Auteur(s) : Chalkiadakis, Eletherios Dufourcq, R. Schmitt, Sophie Brandily, Christophe Kervarec, N. Coatanea, Denis Amir, H. Loubersac, Lionel

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Bulletin officiel de la Guyane française
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Statistique générale et particulière de la France et de ses colonies avec une nouvelle description topographique, physique, agricole, politique, industrielle et commerciale T.3
Auteur(s) : Herbin de Halle, Pierre Etienne (1772-18..) Amaury-Duval (1760-1838 ; Charles-Alexandre-Amaury Pineux) Dumuys Parmentier, Antoine (1737-1813) Deyeux, Nicolas (1745-1837)
Auteurs secondaires : Poirson, Jean-Baptiste (1760-1831) Tardieu, Jean Baptiste Pierre (1746-1816)
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Les magistrats des colonies, depuis l'ordonnance du 18 juillet 1841
Auteur(s) : Just, Maximilien
Auteurs secondaires : Schoelcher, Victor (1804-1893)
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Traité de la couleur de la peau humaine en général, de celle des nègres en particulier, et de la métamorphose d'une de ces couleurs en l'autre, soit de naissance, soit accidentellement
Auteur(s) : Le Cat, Claude-Nicolas (1700-1768)
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Bulletin officiel de la Guyane française
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Cinq semaines à travers la forêt Guyanaise
Auteur(s) : Quris, Bernard
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Primary Silica-rich Picrite and High-Ca Boninite Melt Inclusions in Pyroxenite Veins from the Kamchatka Sub-arc Mantle
Auteur(s) : Benard, A. Nebel, O. IONOV, Dmitri Arculus, R. j. Shimizu, N. Metrich, N.
Auteurs secondaires : Research School of Earth Sciences [Canberra] (RSES) ; Australian National University (ANU) Géosciences Montpellier ; Université des Antilles et de la Guyane (UAG) - Institut national des sciences de l'Univers (INSU - CNRS) - Université de Montpellier (UM) - Centre National de la Recherche Scientifique (CNRS) Manteau et Interfaces ; Géosciences Montpellier ; Université des Antilles et de la Guyane (UAG) - Institut national des sciences de l'Univers (INSU - CNRS) - Université de Montpellier (UM) - Centre National de la Recherche Scientifique (CNRS) - Université des Antilles et de la Guyane (UAG) - Institut national des sciences de l'Univers (INSU - CNRS) - Université de Montpellier (UM) - Centre National de la Recherche Scientifique (CNRS) Woods Hole Oceanographic Institution (WHOI) Institut de Physique du Globe de Paris (IPGP) ; Institut national des sciences de l'Univers (INSU - CNRS) - IPG PARIS - Université Paris Diderot - Paris 7 (UPD7) - Université de la Réunion (UR) - Centre National de la Recherche Scientifique (CNRS)

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
Island arc picrites and boninites are magnesian magmatic rocks believed to be generated by high degrees of melting of depleted mantle sources fluxed by subduction-derived, volatile-rich components. These magmas can be probes of both the mantle wedge protoliths and subduction components, but are rare among other, usually more evolved, types of arc lavas. Furthermore, many arc picrites and boninites show evidence for late-stage differentiation prior to or during eruption, masking their primary, mantle-derived geochemical signatures. We report textural and chemical data on spinel-hosted melt inclusions of mantle origin in amphibole-bearing websterite veins cross-cutting spinel harzburgite xenoliths from the active andesitic Avacha volcano (south Kamchatka, Russia). The data are used to constrain the composition and origin of melts that formed the websterite veins in the sub-arc lithospheric mantle. The melt inclusions typically contain euhedral orthopyroxene and clinopyroxene and occasionally minor amphibole in silicate glass. The melt inclusions were homogenized using heating stages and gas-mixing furnaces. The homogenized glasses range from subalkaline primitive silica-rich picrite and high-Ca boninite (>15 wt % MgO, 48–54 wt % SiO2) to rhyolite. High-Ca boninite glasses have moderate volatile and low heavy rare earth element contents and elevated Cs, Rb, Ba, U, Sr, and Li abundances, with extremely high U/Th. In turn, the glasses display no negative spikes in the high field strength elements Nb, Ta, Zr, Hf, and Ti. We show that the silica-rich picrite and high-Ca boninite liquids in this study formed by high degrees of melting (>25%), at volatile under-saturation, of hybrid melt-depleted but silica-rich mantle sources at ≥1·5 GPa. The hybrid sources formed in two stages: first, by extraction of ∼15% melt from the convecting mantle to form a refractory protolith, which was subsequently enriched in silica via interaction with subduction-derived components prior to or during remelting in the mantle wedge. The subduction-derived components were enriched in fluid-mobile elements and probably oxidized. Overall, our results suggest that silica-rich picrites and high-Ca boninites can be primary melts in mature subduction zones and differentiate within the mantle wedge and the deep arc crust to form more evolved andesite magmas.
ISSN: 0022-3530

hal-01553676
https://hal.archives-ouvertes.fr/hal-01553676
DOI : 10.1093/petrology/egw066

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