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  • 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology  (5)
  • AMI Associazione Micromineralogica Italiana  (2)
  • Mineralogical Society of America  (2)
  • American Meteorological Society (AMS)
  • Nature Publishing Group
Collection
Years
  • 1
    Publication Date: 2017-04-04
    Description: In this study, we have used electron-microprobe mapping to investigate plagioclase compositional evolution due to cooling kinetics. We re-analyzed five run-products from a prior study (Iezzi et al. 2011), crystallized by cooling a natural andesitic melt from 1300 to 800 °C at 25, 12.5, 3, 0.5, and 0.125 °C/min under atmospheric pressure and air redox state. As the cooling rate decreases, the texture of large plagioclases changes from skeletal to hollow to nearly equant. In this study, we use X‑ray map data to obtain a database of 12 275 quantitative chemical analyses. The frequency of An-rich plagioclases showing disequilibrium compositions substantially increases with increasing cooling rate. At 25 and 12.5 °C/min the distribution is single-mode and narrow, at 0.5 and 0.125 °C/min is single-mode but very broad, whereas at the intermediate cooling rate of 3 °C/min two distinct plagioclase populations are present. This intermediate cooling rate is fast enough to cause departure from equilibrium for the crystallization of the An-rich population but also sufficiently slow that An-poor plagioclases nucleate from the residual melt. We interpret our findings in the context of time-temperature-transformation (TTT) diagrams, and infer the crystallization kinetics of plagioclase in the experiments. Compositional trends and our inferences regarding TTT systematics are consistent with two discrete nucleation events that produced separate populations of plagioclase (i.e., An-rich and An-poor populations) at 3 °C/min. Using plagioclase-melt pairs as input data for the thermometric reaction between An and Ab components, we find that plagioclase mirrors very high- (near-liquidus) crystallization temperatures with increasing cooling rate. These results have important implications for the estimate of post-eruptive solidification conditions. Lava flows and intrusive bodies from centimeters to a few meters thick are characterized by a short solidification time and a significant thermal diffusion. Under such circumstances, it is possible to crystallize plagioclases with variable and disequilibrium chemical compositions simply by cooling a homogeneous andesitic melt. X‑ray element maps enrich the study of plagioclase compositional variations generated under conditions of rapid cooling.
    Description: Published
    Description: 898-907
    Description: 2IT. Laboratori sperimentali e analitici
    Description: JCR Journal
    Description: open
    Keywords: Cooling rate ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2017-04-04
    Description: In recent decades, geophysical investigations have detected wide magma reservoirs beneath quiescent calderas. However, the discovery of partially melted horizons inside the crust is not sufficient to put constraints on capability of reservoirs to supply cataclysmic eruptions, which strictly depends on the chemical-physical properties of magmas (composition, viscosity, gas content etc.), and thus on their differentiation histories. In this study, by using geochemical, isotopic and textural records of rocks erupted from the high-risk Campi Flegrei caldera, we show that the alkaline magmas have evolved toward a critical state of explosive behaviour over a time span shorter than the repose time of most volcanic systems and that these magmas have risen rapidly toward the surface. Moreover, similar results on the depth and timescale of magma storage were previously obtained for the neighbouring Somma-Vesuvius volcano. This consistency suggests that there might be a unique long-lived magma pool beneath the whole Neapolitan area.
    Description: Published
    Description: article 712
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: N/A or not JCR
    Description: open
    Keywords: magma ; campi flegrei caldera ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
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    Unknown
    AMI Associazione Micromineralogica Italiana
    Publication Date: 2017-04-04
    Description: In the small vacuoles of an older lava from one of the quarries of Villa Inglese (Torre del Greco, Napoli) atacamite as crystalline have been discovered. This is a rare event in this volcanic complex.
    Description: Published
    Description: 62-63
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: N/A or not JCR
    Description: open
    Keywords: atacamite ; fayalite ; Vesuvio ; Villa Inglese ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
    facet.materialart.
    Unknown
    AMI Associazione Micromineralogica Italiana
    Publication Date: 2020-02-24
    Description: Due to the large amount of "merlinoite" observed in numerous private and public collections and sure that not all have been carefully analyzed, this paper wants to draw attention to the fact that the distinction at "view" of phillipsite and merlinoite from and merlinoite from Vesuvius is impossible.
    Description: Published
    Description: 64-65
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: N/A or not JCR
    Description: open
    Keywords: merlinoite ; phillipsite ; Monte Somma ; Vesuvio ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
    Publication Date: 2020-12-14
    Description: Two small outcrops of wollastonite- and melilite-bearing paralavas, with a pyrometamorphic genesis, have been found along the Apennine chain, in Central Italy, at the localities of Colle Fabbri and Ricetto. Recent papers added new data strengthening the hypothesis that the Ricetto wollastonite- and melilite-bearing rocks were produced by pyrometamorphism of carbonate-rich siliciclastic sedimentary rocks. In addition, these new papers depicted the Ricetto paralavas as having wide mineralogical and compositional variations due to liquid immiscibility and/or carbonate devolatilization, paralleling the trend observed for other paralavas (e.g., Colle Fabbri, Italy; British Columbia, Canada; Wyoming, U.S.A.; etc.). The source of heat for inducing pyrometamorphism was not investigated in the original paper, which was the subject of the comment. Capitanio et al. (2004), on the basis of 14C age determination and of a mineralogical study, argued convincingly that heat was supplied to the Ricetto rocks by wood-combustion for charcoal production.
    Description: Published
    Description: 1940-1944
    Description: partially_open
    Keywords: rock composition ; Italian wollastonite ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology ; 04. Solid Earth::04.04. Geology::04.04.07. Rock geochemistry
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Format: 489 bytes
    Format: 449657 bytes
    Format: text/html
    Format: application/pdf
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