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  1. Cristobalite in volcanic ash of the Soufriere Hills volcano, Montserrat, British West Indies.

    Article - En anglais

    Crystalline silica (mostly cristobalite) was produced by vapor-phase crystallization and devitrification in the andesite lava dome of the Soufriere Hills volcano, Montserrat.

    The sub-10-micrometer fraction of ash generated by pyroclastic flows formed by lava dome collapse contains 10 to 24 weight percent crystalline silica, an enrichment of 2 to S relative to the magma caused by selective crushing of the groundmass.

    The sub-10-micrometer fraction of ash generated by explosive eruptions has much lower contents (3 to 6 percent) of crystalline silica.

    High levels of cristobalite in respirable ash raise concerns about adverse health effects of long-term human exposure to ash from lava dome eruptions.

    Mots-clés Pascal : Iles Caraïbes, Région des Caraïbes, Ile Montserrat, Iles Sous le Vent, Petites Antilles, Antilles, Cristobalite, Silice minéral, Tectosilicate, Silicate, Cendre volcanique, Dévitrification, Verre volcanique, Roche volcanique, Roche ignée, Coulée pyroclastique, Effondrement, Dôme, Andésite, Eruption, Explosion, Pyroclastite, Diffraction RX, Diagramme poudre, Résonance magnétique nucléaire, Spectre RMN, Analyse éléments majeurs, Fluorescence RX, Donnée microsonde électronique, Volcan Soufriere Hills, Si 29

    Mots-clés Pascal anglais : West Indies, Caribbean region, Montserrat, Leeward Islands, Lesser Antilles, Antilles, cristobalite, silica minerals, framework silicates, silicates, volcanic ash, devitrification, volcanic glass, volcanic rocks, igneous rocks, pyroclastic flows, collapse, domes, andesites, eruptions, explosions, pyroclastics, X-ray diffraction, powder diagrams, nuclear magnetic resonance, NMR spectra, major-element analyses, X-ray fluorescence, electron probe data

    Logo du centre Notice produite par :
    Inist-CNRS - Institut de l'Information Scientifique et Technique

    Cote : 99-0176578

    Code Inist : 001E01F01. Création : 16/11/1999.