Search results for "Microanalytical method"

showing 2 items of 2 documents

Volatiles in pantellerite magmas: A case study of the Green Tuff Plinian eruption (Island of Pantelleria, Italy)

2013

Abstract The Green Tuff (GT) Plinian eruption, the largest in magnitude at Pantelleria, erupted 3 to 7 km3 DRE of pantellerite magma and a small volume of trachyte. Fifty-nine anorthoclase-hosted melt inclusions from the two basal pumice members were analyzed by FT-IR spectroscopy in order to assess the pre-eruptive H2O content in the pantellerite melt. Microanalytical methods were used to determine major element, Cl, F and S contents. Melt inclusions and glassy groundmasses have a nearly homogeneous pantelleritic composition (peralkaline index = 1.9-2.2) and variable water contents ranging from 1.4 to as high as 4.2 wt %, i.e. much higher than the 1.4 wt % of earlier published studies. The…

LavaSettore GEO/07 - Petrologia E PetrografiaGeochemistryTrachyteMagma chamberStrombolian eruptionGeophysicsEffusive eruptionGeochemistry and PetrologyPumiceMagmaThe Green Tuff (GT) Plinian eruption the largest in magnitude at Pantelleria erupted 3 to 7 km 3 DRE of pantellerite magma and a small volume of trachyte. Fifty-nine anorthoclase-hosted melt inclusions from the two basal pumice members were analyzed by FT-IR spectroscopy in order to assess the pre-eruptive H2Ocontent in the pantellerite melt. Microanalytical methods were used to determine major element Cl F and S contents. Melt inclusions and glassy groundmasses have a nearly homogeneous pantelleritic composition (peralkaline index = 1.9-2.2) and variable water contents ranging from 1.4 to as high as 4.2 wt % i.e. much higher than the 1.4 wt % of earlier published studies. The chlorine content is constant at about 1 wt %. Combined Cl and H2O data were used to estimate a confining pressure of about 50 MPa (depth around 2-3 km) for the GT magma chamber. The chamber was characterized by a compositional zoning with a dominant pantellerite overlying a trachyte magma. Soon after the GT eruption intra-caldera volcanism was dominated by the eruption of voluminous trachyte lavaflows while pantellerite melt production resumed after about 20 ka with numerous low-volume mildly explosive (Strombolian) to effusive eruptions. Comparison with data from the literature reveals that despite the differentexplosivity the post-caldera Strombolian eruptions and the GT Plinian eruption were fed by pantelleritic magmas with similar water contents. Chlorine and CO2contents suggest that the young magma reservoirs feeding the Strombolian to effusive activity were deeper (h≥4.5 km) than the much larger (based on erupted volumes) magma chamber which fed the GT eruptionGeologyMelt inclusionsJournal of Volcanology and Geothermal Research
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Microanalytical method for studying paintings by use of fluorescence spectroscopy combined with principal component analysis

2013

Abstract The study of several different naturally aged films of organic painting materials, is described. Materials studied include drying oils (walnut, poppy seed and linseed oil) resin-based paint varnishes (the triterpenoid dammar and the diterpenoids sandarac and turpentine) and protein-based binding media (egg yolk and casein). A not expensive methodology for a rapid identification of binding media and varnishes, that applies principal component analysis (PCA) to Excitation Emission (EE) fluorescence spectra, is proposed. PCA was performed on a data matrix where the rows represent studied materials and columns the variables; the variables include the fluorescence intensities associated…

PCAPaintingChromatographyfood.ingredientChemistryOil paintingVarnishSandaracAnalytical chemistryPoppy seedFluorescenceSettore CHIM/12 - Chimica Dell'Ambiente E Dei Beni CulturaliFluorescence spectroscopyAnalytical ChemistryPaintingMicroanalytical methodfoodLinseed oilvisual_artBinding mediavisual_art.visual_art_mediumSettore CHIM/01 - Chimica AnaliticaFourier transform infrared spectroscopySpectroscopyMicrochemical Journal
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