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  • Polymer and Materials Science  (2)
  • Thorium  (1)
  • calculation
  • Equisetum
  • pollen analytical standard techniques
  • R/V Vereshchagin
  • 2005-2009  (1)
  • 1970-1974  (2)
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  • 1
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    Crustal residence times of explosive phonolite magmas: U–Th ages of magmatic Ca-Garnets of Mt. Somma-Vesuvius (Italy) (2008)
    Elsevier
    Details
    Publication Date: 2021-06-16
    Description: Assessing the residence times of phonolite magmas in the shallow crust contributes to the understanding of explosive volcanic systems. Estimations of that by dating the residence time of a mineral in a melt was difficult in the past, because e.g. of the lack of evidence for the co-genetic character of the crystals dated. Here we present an estimate for the residence time of a phonolite magma feeding the Pomici di Mercato Plinian eruption (8890±90 cal years BP) of Mt. Somma-Vesuvius (Southern Italy), employing U–Th disequilibrium dating of unzoned Ca-rich phenocrystic magmatic garnets. Based on combined textural, geochemical, and Sr- O isotope evidence, these garnets can be identified as co-genetic with their host phonolites. Furthermore, experimental and petrological data suggest that Ca-garnets can be a liquidus phase in highly differentiated phonolite magmas of Mercato. A whole-rock–glass–garnet U–Th isochron gives a crystallisation age for the Ca-rich garnets of 14,400±1100 a (2σ). This implies a Ca-garnet residence time of 5510±1100 years (2σ) in the Mercato phonolite melt prior to eruption and provides one of the first robust estimates of how long explosive phonolite magma has resided in the shallow crust before eruption. Calculations of magma cooling rates and settling velocities of the Ca-garnets confirm that garnet-bearing phonolite can remain liquid and the garnets remain suspended in a magma chamber for as long as 5510 years before the time of eruption. Processes which may have disturbed the U–Th isotope systematic of the samples, such as assimilation, recharge or surface alteration can be ruled out.
    Description: Published
    Description: 293-301
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: Uranium ; Thorium ; U–Th isotopes ; Somma-Vesuvius ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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    PAPER (OA)
  • 2
    Electronic Resource
    Electronic Resource
    Über den Mechanismus des Elektropolierens von Molybdän in nichtwäßrigen Elektrolyten (1974)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 25 (1974), S. 906-909 
    Details
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Mechanism of the electropolishing of molybdenum in nonaqueous electrolytesMeasurements carried out on molybdenum electrodes in solutions of magnesium per-chlorate and lithium chloride in ethanol dimethylsulphoxide and dimethyl form-amide have shown that the metal can be electropolished in solutions containing perchlorate. The formal valency (nformal) of the molybdenum dissolution in the electropolishing region, as determined from the weight loss of the electrode and the charge transferred is 3≤n formal≤ 2,75.
    Notes: Es wurden Messungen an Molybdänelektroden in Lösungen von Magnesiumperchlorat und Lithiumchlorid in Äthanol, Dimethylsulfoxid und Dimethylformamid durchgeführt.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19740251206
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Elektrochemische Untersuchungen an Molybdän (1971)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 22 (1971), S. 115-120 
    Details
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Electrochemical studies on molybdenumThe authors show, that the power law found during earlier measurements is valid for at least five decimal powers of the time. The correlation derived from potentiostatic switch-in measurements has been confirmed by galvanostatic tests. The results give rise to the assumption that the kinetic law has its origin in the rates of the reactions resulting in metal dissolution. In order to elucidate these reactions a triangle potential method has been used. The findings enable a first suggestion to be made as to the reaction sequence.
    Notes: Es wird gezeigt, daß das aus früheren Messungen gefundene Potenzgesetz wenigstens über fünf Zehnerpotenzen der Zeit gültig ist. Der aus potentionstatischen Einschaltmessungen hergeleitete Zusammenhang wurde durch galvanostatische Versuche bestätigt. Die Ergebnisse deuten darauf hin, daß das Zeitgesetz seinen Ursprung im Ablauf der zur Metallauflösung führenden Reaktionen hat. Zur Klärung dieser Reaktionen wurde die Dreiecksspannungsmethode angewendet. Der Meßbefund erlaubt es, einen ersten Vorschlag über die Reaktionsfolge zu machen.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19710220202
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