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  • 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
  • INGV  (9)
  • Nature Publishing Group  (2)
  • Springer Science + Business Media
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  • 1
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    Dynamic feeder dyke systems in basaltic volcanoes: the exceptional example o fthe 1809 Etna eruption (Italy) (2015)
    Nature Publishing Group
    Details
    Publication Date: 2017-04-04
    Description: In this paper, we describe the 1809 eruption of Mt. Etna, Italy, which represents one historical rare case in which it is possible to observe details of the internal structure of the feeder system. This is possible thanks to the presence of two large pit craters located in the middle of the eruptive fracture field that allow studying a section of the shallow feeder system. Along the walls of one of these craters, we analysed well-exposed cross sections of the uppermost 15–20 m of the feeder system and related volcanic products. Here, we describe the structure, morphology and lithology of this portion of the 1809 feeder system, including the host rock which conditioned the propagation of the dyke, and compare the results with other recent eruptions. Finally, we propose the dynamic model of the magma behaviour inside a laterally-propagating feeder dyke, demonstrating how this dynamic triggered important changes in the eruptive style (from effusive/Strombolian to phreatomagmatic) during the same eruption. Our results are also useful for hazard assessment related to the development of flank eruptions, potentially the most hazardous type of eruption from basaltic volcanoes in densely urbanized areas, such as Mt. Etna.
    Description: Published
    Description: 1-11
    Description: 2T. Tettonica attiva
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: 3V. Dinamiche e scenari eruttivi
    Description: 4V. Vulcani e ambiente
    Description: 6A. Monitoraggio ambientale, sicurezza e territorio
    Description: N/A or not JCR
    Description: open
    Keywords: feeder dyke ; basaltic volcanoes ; flank eruptions ; Etna ; volcanic hazards ; sill ; volcanic rift ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
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    A model of sulphur solubility for hydrous mafic melts: application to the determination of magmatic fluid compositions of Italian volcanoes (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: We present an empirical model of sulphur solubility that allows us to calculate f S2 if P, T, fO2 and the melt composition, including H2O and S, are known. The model is calibrated against three main experimental data bases consisting in both dry and hydrous silicate melts. Its prime goal is to calculate the f S2 of hydrous basalts that currently lack experimental constraints of their sulphur solubility behaviour. Application of the model to Stromboli, Vesuvius, Vulcano and Etna eruptive products shows that the primitive magmas found at these volcanoes record f S2 in the range 0.1-1 bar. In contrast, at all volcanoes the magmatic evolution is marked by dramatic variations in f S2 that spreads over up to 9 orders of magnitude. The f S2 can either increase during differentiation or decrease during decompression to shallow reservoirs, and seems to be related to closed versus open conduit conditions, respectively. The calculated f S2 shows that the Italian magmas are undersaturated in a FeS melt, except during closed conduit conditions, in which case differentiation may eventually reach conditions of sulphide melt saturation. The knowledge of f S2, fO2 and fH2O allows us to calculate the fluid phase composition coexisting with magmas at depth in the C-O-H-S system. Calculated fluids show a wide range in composition, with CO2 mole fractions of up to 0.97. Except at shallow levels, the fluid phase is generally dominated by CO2 and H2O species, the mole fractions of SO2 and H2S rarely exceeding 0.05 each. The comparison between calculated fluid compositions and volcanic gases shows that such an approach should provide constraints on both the depth and mode of degassing, as well as on the amount of free fluid in magma reservoirs. Under the assumption of a single step separation of the gas phase in a closed-system condition, the application to Stromboli and Etna suggests that the main reservoirs feeding the eruptions and persistent volcanic plumes at these volcanoes might contain as much as 5 wt% of a free fluid phase. Consideration of the magma budget needed to balance the amounts of volatiles emitted in the light of these results shows that the amount of nonerupted magma could be overestimated by as much as one order of magnitude.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: sulphur ; hydrous basalts ; volcanic gas ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 3
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    Volatile diffusion in silicate melts and its effects on melt inclusions (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: A compendium of diffusion measurements and their Arrhenius equations for water, carbon dioxide, sulfur, fluorine, and chlorine in silicate melts similar in composition to natural igneous rocks is presented. Water diffusion in silicic melts is well studied and understood, however little data exists for melts of intermediate to basic compositions. The data demonstrate that both the water concentration and the anhydrous melt composition affect the diffusion coefficient of water. Carbon dioxide diffusion appears only weakly dependent, at most, on the volatilefree melt composition and no effect of carbon dioxide concentration has been observed, although few experiments have been performed. Based upon one study, the addition of water to rhyolitic melts increases carbon dioxide diffusion by orders of magnitude to values similar to that of 6 wt% water. Sulfur diffusion in intermediate to silicic melts depends upon the anhydrous melt composition and the water concentration. In water-bearing silicic melts sulfur diffuses 2 to 3 orders of magnitude slower than water. Chlorine diffusion is affected by both water concentration and anhydrous melt composition; its values are typically between those of water and sulfur. Information on fluorine diffusion is rare, but the volatile-free melt composition exerts a strong control on its diffusion. At the present time the diffusion of water, carbon dioxide, sulfur and chlorine can be estimated in silicic melts at magmatic temperatures. The diffusion of water and carbon dioxide in basic to intermediate melts is only known at a limited set of temperatures and compositions. The diffusion data for rhyolitic melts at 800°C together with a standard model for the enrichment of incompatible elements in front of growing crystals demonstrate that rapid crystal growth, greater than 10-10 ms-1, can significantly increase the volatile concentrations at the crystal-melt interface and that any of that melt trapped by the formation of melt inclusions may not be representative of the bulk melt. However, basaltic melt inclusions trapped at 1300°C are more likely to contain bulk melt concentrations of water and carbon dioxide.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: diffusion ; silicate melts ; volatiles ; water ; carbon dioxide ; sulfur ; fluorine ; igneous processes ; chlorine ; melt inclusion ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 4
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    Determination of volatiles in volcanic rocks and minerals with a Directly Coupled Evolved Gas Analyzing System (DEGAS) -Part I: Interpretation of degassing profiles (DEGAS-profiles) of minerals and rocks on the basis of melting experiments (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: Volatile components in magma strongly influence many physical properties of melts and minerals. The temperature resolved degassing analysis of volcanic crystalline and vitreous rocks gives detailed information about volatile compounds in the melt. Aspecial high-temperature mass-spectrometry device in combination with a thermo-balance allows a quantitative determination of different volatile species. It enables a differentiation between the primary gas content in the magma and the gas released from decomposition of secondary alteration products. The gas release profiles give the following indications: i) during the littoral explosions of Pahoehoe lava the content of volatiles is not changed by interaction with air or sea water; ii) the degassing profiles of vitreous black sand verify the primary content of volatiles in the erupted melt, only CO2 was detected; iii) the oxygen release profile gives significant indications for oxygen undersaturation of the erupted magma; iv) remelting of black sand in air at 1450°C for 0.45 h causes an oxygen saturation of the basaltic melt; v) remelting of black sand in argon atmosphere confirms the oxygen undersaturation of the melt; vi) remelting of black sand-black shale mixtures affects a significant change in the degassing profiles, especially in CO2-release. With the first investigations we can demonstrate that gas release curves of volcanic rocks are qualified for a) detection of the primary gas content of erupted magma; b) detection of alteration processes of the igneous glass; c) detection of contamination of the magma with adjacent rocks.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: volatiles ; magmatic rocks ; basaltic glass ; degassing ; Hawaiian lava ; remelting ; blacksand ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 5
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    Evolution of the volcanic plumbing systemof Alicudi (Aeolian Islands - Italy): evidence from fluid and melt inclusionsin quartz xenoliths (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: Quartz-rich xenoliths in lavas (basalts to andesites; 90-30 ka) from Alicudi contain abundant melt and fluid inclusions. Two generations of CO2-rich fluid inclusions are present in quartz-rich xenolith grains: early (Type I) inclusions related to partial melting of the host xenoliths, and late Type II inclusions related to the fluid trapping during xenolith ascent. Homogenisation temperatures of fluid inclusions correspond to two density intervals: 0.93-0.68 g/cm3 (Type I) and 0.47-0.26 g/cm3 (Type II). Early Type I fluid inclusions indicate trapping pressures around 6 kbar, which are representative for the levels of partial melting of crustal rocks and xenolith formation. Late Type II fluid inclusions show lower trapping pressures, between 1.7 kbar and 0.2 kbar, indicative for shallow magma rest and accumulation during ascent to the surface. Data suggest the presence of two magma reservoirs: the first is located at lower crustal depths (about 24 km), site of fractional crystallization, mixing with source derived magma, and various degrees of crustal assimilation. The second magma reservoir is located at shallow crustal depths (about 6 km), the site where magma rested for a short time before erupting.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: Aeolian Islands ; fluid inclusions ; crustal xenoliths ; homogenisation temperature ; magma plumbing system ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
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    Rapid differentiation in a sill-like magma reservoir: a case study from the campi flegrei caldera (2012)
    Nature Publishing Group
    Details
    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
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  • 7
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    Fe in magma - An overview (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: The strong influence of physical conditions during magma formation on Fe equilibria offers a large variety of possibilities to deduce these conditions from Fe-bearing phases and phase assemblages found in magmatic rocks. Conditions of magma genesis and their evolution are of major interest for the understanding of volcanic eruptions. A brief overview on the most common methods used is given together with potential problems and limitations. Fe equilibria are not only sensitive to changes in intensive parameters (especially T and fO2) and extensive parameters like composition also have major effects, so that direct application of experimentally calibrated equilibria to natural systems is not always possible. Best estimates for pre-eruptive conditions are certainly achieved by studies that relate field observations directly to experimental observations for the composition of interest using as many constraints as possible (phase stability relations, Fe-Ti oxides, Fe partitioning between phases, Fe oxidation state in glass etc.). Local structural environment of Fe in silicate melts is an important parameter that is needed to understand the relationship between melt transport properties and melt structure. Assignment of Fe co-ordination and its relationship to the oxidation state seems not to be straightforward. In addition, there is considerable evidence that the co-ordination of Fe in glass differs from that in the melt, which has to be taken into account when linking melt structure to physical properties of silicate melts at T and P.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: iron ; silicate melt ; redox conditions ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics
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  • 8
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    Chlorine solubility in evolved alkaline magmas (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: Experimental studies of Cl solubility in trachytic to phonolitic melts provide insights into the capacity of alkaline magmas to transport Cl from depth to the earths surface and atmosphere, and information on Cl solubility variations with pressure, temperature and melt or fluid composition is crucial for understanding the reasons for variations in Cl emissions at active volcanoes. This paper provides a brief review of Cl solubility experiments conducted on a range of trachytic to phonolitic melt compositions. Depending on the experimental conditions the melts studied were in equilibrium with either a Cl-bearing aqueous fluid or a subcritical assemblage of low- Cl aqueous fluid + Cl-rich brine. The nature of the fluid phase(s) was identified by examination of fluid inclusions present in run product glasses and the fluid bulk composition was calculated by mass balance. Chlorine concentrations in the glass increase with increasing Cl molality in the fluid phase until a plateau in Cl concentration is reached when melt coexists with aqueous fluid + brine. With fluids of similar Cl molality, higher Cl concentrations are observed in peralkaline phonolitic melts compared with peraluminous phonolitic melts; overall the Cl concentrations observed in phonolitic and trachytic melts are approximately twice those found in calcalkaline rhyolitic melts under similar conditions. The observed negative pressure dependence of Cl solubility implies that Cl contents of melts may actually increase during magma decompression if the magma coexists with aqueous fluid and Cl-rich brine (assuming melt-vapor equilibrium is maintained). The high Cl contents (approaching 1 wt% Cl) observed in some melts/glasses from the Vesuvius and Campi Flegrei areas suggest saturation with a Cl-rich brine prior to eruption.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: alkaline magmas ; solubility ; chlorine ; supercritical fluid ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
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    Solubility of C-O-H mixturesin natural melts: new experimental data and application range of recent models (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: The effect of pressure, temperature, and melt composition on CO2 and H2O solubilities in aluminosilicate melts, coexisting with CO2-H2O fluids, is discussed on the basis of previously published and new experimental data. The datasets have been chosen so that CO2 and H2O are the main fluid components and the conclusions are only valid for relatively oxidizing conditions. The most important parameters controlling the solubilities of H2O and CO2 are pressure and composition of melt and fluid. On the other hand, the effect of temperature on volatile solubilities is relatively small. At pressures up to 200 MPa, intermediate compositions such as dacite, in which both molecular CO2 and carbonate species can be dissolved, show higher volatile solubilities than rhyolite and basalt. At higher pressures (0.5 to 1 GPa), basaltic melts can incorporate higher amounts of carbon dioxide (by a factor of 2 to 3) than rhyolitic and dacitic melts. Henrian behavior is observed only for CO2 solubility in equilibrium with H2O-CO2 fluids at pressures 〈100 MPa, whereas at higher pressures CO2 solubility varies nonlinearly with CO2 fugacity. The positive deviation from linearity with almost constant CO2 solubility at low water activity indicates that dissolved water strongly enhances the solubility of CO2. Water always shows non-Henrian solubility behavior because of its complex dissolution mechanism (incorporation of OH-groups and H2O molecules in the melt). The model of Newman and Lowenstern (2002), in which ideal mixing between volatiles in both fluid and melt phases is assumed, reproduces adequately the experimental data for rhyolitic and basaltic compositions at pressures below 200 MPa but shows noticeable disagreement at higher pressures, especially for basalt. The empirical model of Liu et al. (2004) is applicable to rhyolitic melts in a wide range of pressure (0-500 MPa) and temperature (700- 1200°C) but cannot be used for other melt compositions. The thermodynamic approach of Papale (1999) allows to calculate the effect of melt composition on volatile solubilities but needs an update to account for more recent experimental data. A disadvantage of this model is that it is not available as a program code. The review indicates a crucial need of new experimental data for scarcely investigated field of pressures and fluid compositions and new models describing evident non-ideality of H-C-O fluid solubility in silicate melts at high pressures.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: CO2 ; H2O ; solubility ; mixed fluid ; silicate melt ; experimental data ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
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    The 3550 year BP-1944 A.D.magma-plumbing system of Somma-Vesuvius: constraints on its behaviour and present state through a review of Sr-Nd isotope data (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: Vesuvius, dominating the densely-populated Neapolitan area, is one of the most dangerous volcanoes in the World. Its destructive power derives from energetic subplinian and plinian eruptions, such as the one which occurred in 79 A.D. Generally such large-scale events follow a long period of quiescence; a behaviour interpreted as the gradual build-up of magma volumes between periods of major activity. After the 1631 subplinian eruption until the last 1944 A.D. eruption, it experienced an almost continuous and less energetic explosive/effusive activity. The erupted magmas are characterized by undersaturated potassic to ultrapotassic nature, and compositional and Sr-isotopic variability. Furthermore geobarometric studies indicate two different crystallization depths located at 4 and 〉11 km, respectively. According to most of the recent literature, the eruptions were triggered by the injection in a shallower magma chamber, of isotopically distinct magma batches derived from heterogeneous mantle source(s) and/or contamination processes occurred within the deep reservoir. In our review of petrochemical data, we consider the period between the 3550 years BP plinian eruption and the 472 A.D. sub-plinian eruption, which includes 79 A.D. event, and the most recent period of activity which started in 1631 A.D. and lasted up to the 1944 A.D. eruption, characterized by a near continuous effusive/explosive activity. For both periods we identify a correlation between Sr-isotopical features of magmas and their crystallization depth. In particular, we show that pyroxenes have Sr-isotopic ratios lower than 0.7074 and an equilibrium crystallization depth of 22-11 km. Moreover feldspars have higher 87Sr/86Sr values (0.7075-7) and an equilibrium crystallization depth of about 4 km. Therefore the most radiogenic magmas did not derive from a deeper reservoir but their higher Sr-isotopic ratios have been acquired at a shallower depth likely by crustal contamination during magma evolution. In contrast, the lower Sr-isotope compositions characterise the less contaminated magmas coming from deeper crustal levels. On the basis of this evidence, the temporal Sr-isotopical variation of magma which erupted in the 1631-1944 A.D. period probably derives from the progressive withdrawal of the shallow magma chamber, which was completely empty before the 1805-1944 A.D. period of volcanism. Therefore the effusive and explosive events of the most recent 1805-1944 A.D. period were fed directly by the deep reservoir located at a depth exceding 11 km.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: Somma-Vesuvius ; magma chamber ; crustal contamination ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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