ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Publication Date: 2017-04-03
    Description: Volcanic eruptions are characterized by intense degassing, thus it is imperative to have high quality laboratory data to constrain degassing mechanisms. In order to investigate bubble formation and growth at 1 atm, degassing experiments using a Stromboli basalt were performed on the GSECARS X-ray beamline at the Advanced Photon Source. Volatile-bearing glasses were synthesized at 1250 °C and 1000 MPa in a piston cylinder with H2O or mixtures of H2O+CO2; they were then heated in-situ on the X-ray beamline at 1 atm. Bubble growth was observed in-situ using X-ray radiography. The 3D bubble size distributions in the quenched samples and a natural Stromboli pumice were studied by synchrotron X-ray microtomography. The results show that bubble nucleation and growth in basaltic melts are volatile-concentration dependent. Bubbles can easily form in melts initially containing high volatile concentrations. The effect of CO2 on bubble nucleation and growth becomes significant at large CO2 concentrations of 880 to 1480 ppm, but is not important at lower concentrations. Multiple nucleation events occur in most of these degassing experiments, and they are more pronounced in more supersaturated melts. Bubble growth is controlled by viscosity near glass transition temperatures and by diffusion at higher temperatures. Bubbles begin to pop 10 to 20 s after a foam is developed at vesicularities of 65% to 83%. Bubble size distributions follow power–law relations at vesicularities of 1% to 65%, and bubble size distributions evolve from power–law relations to exponential relations at vesicularities of 65% to 83%. This evolution is associated with the change from far-from-equilibrium degassing to near-equilibrium degassing. During far-from-equilibrium degassing, multiple nucleation events are pronounced, and possibly account for the generation of power–law relations. When the system reaches near-equilibrium degassing, coalescence is dominant and leads to the formation of bubbles of similar size. Therefore, bubble size distributions are described by exponential relations.
    Description: NSERC
    Description: Published
    Description: 533-547
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: reserved
    Keywords: basalt ; Stromboli ; bubble size distribution ; degassing ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Publication Date: 2017-04-04
    Description: The transport, degassing and atmospheric release of halogens from active volcanism on Earth have been the 12 focus of increasing interest over the last few decades, and have recently been the subject of the 1st workshop 13 on “Halogens in volcanic systems and their environmental impacts” that was held in December of 2007 at 14 Yosemite Lodge in Yosemite National Park, California. As an introduction to this Chemical Geology special 15 issue, collecting contributions from many of the participants at the workshop, we review here recent 16 advances in this field, including experimental and theoretical investigations of halogen behaviour in volcanic 17 and related magmatic systems. We discuss previous research on several aspects of halogen geochemistry, 18 including halogen abundances in the mantle and magmas on Earth; the effects of halogens on phase 19 equilibria and melt viscosities; their partitioning between melt and fluid phase(s) upon decompression, 20 cooling and crystallisation of magmas in the ^ Earth's crust; and their final atmospheric release as volcanic 21 gases. The role of halogens in the genesis of hydrothermal systems and in the transport of ore-forming metals 22 is also reviewed, and we discuss our current understanding of atmospheric processing of volcanic halogens in 23 both the troposphere and stratosphere, and their consequent impacts. In spite of these recent advancements, 24 our current understanding of halogen geochemistry at active volcanoes is still far too fragmentary, and the 25 key questions that require answers from future research are summarised in our conclusions.
    Description: PRIN 2008 and DPC-INGV 1381 2007-2009 grants; NSERC Dis- 1382 covery grant; NSF award EAR 0308866
    Description: In press
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: reserved
    Keywords: Halogens ; Volcanic gas ; Ore deposits ; Atmospheric effects ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Publication Date: 2017-04-04
    Description: The transport, degassing and atmospheric release of halogens from active volcanism on Earth have been the focus of increasing interest over the last few decades, and have recently been the subject of the 1st workshop on “Halogens in volcanic systems and their environmental impacts” that was held in December of 2007 at Yosemite Lodge in Yosemite National Park, California. As an introduction to this Chemical Geology special issue, collecting contributions from many of the participants at the workshop, we review here recent advances in this field, including experimental and theoretical investigations of halogen behaviour in volcanic and related magmatic systems. We discuss previous research on several aspects of halogen geochemistry, including halogen abundances in the mantle and magmas on Earth; the effects of halogens on phase equilibria and melt viscosities; their partitioning between melt and fluid phase(s) upon decompression, cooling and crystallisation of magmas in the Earth's crust; and their final atmospheric release as volcanic gases. The role of halogens in the genesis of hydrothermal systems and in the transport of ore-forming metals is also reviewed, and we discuss our current understanding of atmospheric processing of volcanic halogens in both the troposphere and stratosphere, and their consequent impacts. In spite of these recent advancements, our current understanding of halogen geochemistry at active volcanoes is still far too fragmentary, and the key questions that require answers from future research are summarised in our conclusions.
    Description: Published
    Description: 1-18
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Halogens ; Magmatic fluids ; Ore deposits ; Volcanic degassing ; Volcanic gas ; Atmospheric effects ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Publication Date: 2017-04-04
    Description: The diffusion of the halogens fluorine, chlorine, and bromine was measured in a hawaiitic melt from Mt. Etna at 500 MPa and 1.0 GPa, 1250 to 1450 ºC at anhydrous conditions; the diffusion of F and Cl in the melt was also studied with about 3 wt% of dissolved water. Experiments were performed using the diffusion-couple technique in a piston cylinder. Most experiments were performed with only one halogen diffusing between the halogen-enriched and halogen-poor halves of the diffusion couple, but a few experiments with a mixture of halogens (F, Cl, Br) were also performed in order to investigate the possibility of interactions between the halogens during diffusion. Fluorine and chlorine diffusivity show a very similar behavior, slightly diverging at low temperature. Bromine diffusion is a factor of about 2 to 5 lower than the other halogens in this study. Diffusion coefficients for fluorine range between 2.3x10−11 and 1.4x10−10 m2s−1, for chlorine between 1.1x10−11 and 1.3x10−10 and for bromine between 9.4x10−12 and 6.8x10−11 m2s−1. No pressure effect was detected at the conditions investigated. In experiments involving mixed halogens, the diffusivities appear to decrease slightly (by a factor of ~ 3), and are more uniform among the three elements. However, activation energies for diffusion do not appear to differ between experiments with individual halogens or when they are all mixed together. The effect of water increases the diffusion coefficients of F and Cl by no more than a factor of 3 compared to the anhydrous melt (DF = 4.0x10−11 to 1.6x10−10 m2s−1; DCl = 3.0x10−11 to 1.9x10−10 m2s−1). Comparing our results to the diffusion coefficients of other volatiles in nominally dry basaltic melts, halogen diffusivities are about one order of magnitude lower than H2O, similar to CO2, and a factor of ~5 higher than S. The contrasting volatile diffusivities may affect the variable extent of volatile degassing upon melt depressurization and vesiculation, and can help our understanding of the compositions of rapidly grown magmatic bubbles.
    Description: NSERC Discovery grant INGV-DPC 2004-2006 Projects (V3_6 – Etna)
    Description: Published
    Description: 3570-3580
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: reserved
    Keywords: Diffusion ; Halogens ; Basalt ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Publication Date: 2017-04-04
    Description: Diffusion of halogens has the potential to influence petrogenetic processes in magma chambers and conduit degassing processes. This contribution reviews our current state of knowledge concerning halogen diffusion and the influence of halogens on the diffusion of major elements in silicate melts. The addition of halogens to silicate melts at common, natural concentration levels will have little effect on the diffusion of major elements. However, the differences between the diffusivity of water, the diffusivities of halogens, and the diffusivity of sulfur are significant enough that during melt inclusion entrapment, or during rapid bubble or crystal growth, diffusive fractionation betweenwater and the halogens, and between halogens and sulfur, are expected to occur and can influence the compositions of melt inclusions, crystals and volcanic gases.
    Description: NSERC Discovery grant to D.R.B
    Description: In press
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: reserved
    Keywords: Halogens ; Diffusion ; Magmatic processes ; Volcanic gas ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Publication Date: 2017-04-04
    Description: Fluorine and chlorine diffusion were measured in two natural phonolitic melts, from Vesuvius (Italy) and from Laacher See (Germany), at 0.5 and 1.0 GPa, between 1250 and 1450 °C at anhydrous conditions and with about 2 and 5 wt.% of dissolvedwater. The two different startingmaterials allowus to investigate the alkali effect,Na vs. K, on halogen diffusion.One compositionwas a K-rich (~10wt.%) phonoliticmelt corresponding to thewhite pumice phase of the 79ADeruption of Vesuvius, and the other aNa-rich (~10 wt.%) phonoliticmelt corresponding tomost differentiated melt of the 12,000 BC eruption of Laacher See. The diffusion-couple technique in a piston cylinder was used for the experiments. Experiments were performed with only one halogen diffusing and with the simultaneous diffusion of a halogenmixture (F, Cl, Br) in order to evaluate the interactions between the halogens during diffusion. Diffusion coefficients for F range between 2×10−11m2/s at 1250 °C and 7×10−11m2/s at 1450 °C for the Na-rich melt and between 1×10−11 m2/s at 1250 °C and 8×10−11 m2/s at 1450 °C for the K-rich melt at anhydrous conditions. Diffusion coefficients for Cl range between 2×10−12 m2/s at 1250 °C and 1×10−11 m2/s at 1450 °C for theNa-richmelt and between 7×10−12m2/s at 1250 °C and 2×10−11m2/s at 1450 °C for the K-richmelt at anhydrous conditions. Fluorine diffusivity is higher than Cl in the Na-rich-phonolitic melt by one order of magnitude,whereas in the K-rich-phonoliticmelt F and Cl diffusivities are similar. The effect ofwater is significant for Cl in both Na-rich and K-rich melts: the addition of water enhances Cl diffusivity by up to one order of magnitude, butwater does not significantly affect F diffusion. F and Cl diffusivities always differ fromone another in the same phonoliticmelt composition. F diffusivities are similar in both compositions. Conversely, Cl diffusion depends upon the dominant alkali. These results evidence that halogen diffusivitymay represent a limiting factor for their degassing during rapid syneruptive decompression and vesiculation of H2O-rich-phonolitic melts. The contrasting volatile diffusivities of F and Cl in silicate melts duringmagma vesiculation may be a key, controlling factor of the composition of the vapour phase (bubbles) produced. Such diffusion controlled degassingmodelmay explain the absence of F and Cl degassing observed during the 79AD eruption of Vesuvius.
    Description: IPGP contribution: 2364; Geotop contribution: 2008-0029.
    Description: In press
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: reserved
    Keywords: Diffusio ; Halogenes ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Publication Date: 2017-04-04
    Description: Explosive activity at Stromboli is explained in terms of dynamics of large gas bubbles that ascend in the magma conduit and burst at the free surface generating acoustic pressure that propagates as infrasonic signals in the atmosphere. The rate and the amplitude of the infrasonic activity is directly linked to the rate and the overpressure of the bursting gas bubbles and thus reflects the rate at which magma column degasses under non-equilibrium pressure conditions. We investigate the link between explosive degassing and magma vesiculation by comparing the rate of infrasonic activity with the bubble size distributions (BSDs) of scoria clasts collected during several days of explosive activity at Stromboli. BSDs of scoria show a characteristic power law distribution, which reflect a gas bubble concentration mainly controlled by a combined process of bubble nucleation and coalescence. The cumulative distribution of the infrasonic pressure follows two power laws, indicating a clear separation between the frequent, but weak, bursting of small gas bubbles (puffing) and the more energetic explosions of large gas slugs. The exponents of power laws derived for puffing and explosive infrasonic activity show strongly correlated (0.96) changes with time indicating that when the puffing rate is high, the number of energetic explosions is also elevated. This correlation suggests that both puffing and explosive activity are driven by the same magma degassing dynamics. In addition, changes of both infrasonic power law exponents are very well correlated (0.92 with puffing and 0.87 with explosions) with variations of the BSD exponents of the scoria clasts, providing evidence of the strong interplay between scoria vesiculation and magma explosivity. Our analysis indicates that variable magma vesiculation regimes recorded in the scoria correlate with the event number and energy of the explosive activity. We propose that monitoring infrasound on active volcanoes may be an alternative way to look at the vesiculation process in open conduit systems.
    Description: Published
    Description: 274-280
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: reserved
    Keywords: Strombolian activity ; magma vesiculation ; infrasound ; conduit dynamics ; explosive volcanism ; bubble size distribution ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochemical and Biophysical Research Communications 114 (1983), S. 1189-1193 
    ISSN: 0006-291X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochemical and Biophysical Research Communications 193 (1993), S. 912-918 
    ISSN: 0006-291X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Current Opinion in Cell Biology 5 (1993), S. 966-970 
    ISSN: 0955-0674
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...