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  • 1
    Publication Date: 2021-01-11
    Description: no abstracts
    Description: Unpublished
    Description: Sestri Levante (Ge, Italy)
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: open
    Keywords: alkali feldspars ; trachytic melts ; 05. General::05.01. Computational geophysics::05.01.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Poster session
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  • 2
    Publication Date: 2021-01-11
    Description: The kinetics of hydrated basaltic melts erupted during the present activity at Stromboli have been studied to estimate the growth and dissolution rate of plagioclase. Specifically, a high-K basalt composition (PST-9) has been studied to investigate magma and eruption dynamics at Stromboli volcano by combining crystallization kinetics of plagioclase and CSD measurements on natural samples from literature (Armienti et al., 2007; Fornaciai et al., 2009). A series of water-saturated decompression experiments over a range of final water pressure (Pf = 75–5 MPa) at constant temperature (1075 C) show that plagioclase is systematically present from 50 to 5 MPa at water saturated conditions. Moreover, these experiments show that anorthite (An) content decreases with decreasing PH2O, reaching the same composition as the natural plagioclase in Stromboli scoria at pressure below 20 MPa and that the plagioclase crystal fraction increases as the experimental conditions tend to lower final pressure. Plagioclase growth rate (GL) is observed to increase with undercooling for the Pf investigated during decompression experiments, except for the 75 MPa Pf serie that only has two samples with the presence of plagioclase crystals. The values of GL vary from 10 7 to 10 8 cm/s for Pf from 75 to 25 MPa, while at Pf from 10 to 5 MPa growth rates are approximately of 10 6 cm/s. A series of dissolution experiments at atmospheric pressure and over a range of temperature has been done for plagioclase (T range of 1220–1240 C). Dissolution rate (G-) for plagioclase (10 7 cm/s) tends to be slightly higher at higher temperature in the range of 1220–1240 C and appears to be time independent for the experimental durations investigated (10–30 h). These trends could be related to development of a diffusion-limited boundary layer adjacent to the dissolving crystal. By comparison of the experimental data on plagioclase composition, growth rates and dissolution in Stromboli basalt, it is possible to place the reservoir of the crystal-rich magma in the upper part (from 400 m to the surface) of the volcanic conduit. Kinetic data of the plagioclase, the most important phase of the shallow magmatic system of Stromboli, show that the magmatic processes are quite dynamic and in a relatively short time (hours or several days) the system can change considerably. Furthermore, the results from this work combined with observations on natural samples help to improve our knowledge of the magma plumbing system, of interactions between resident magma and new magmas, the dynamics of volcanic activity of Stromboli, and the time scales of magmatic processes that change in a few hours to 1 month.
    Description: Published
    Description: 135-151
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: Experimental petrology ; Basalts ; magma Kinetics ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
    Publication Date: 2018-03-23
    Description: Isothermal single-step decompression experiments (at temperature of 1075 °C and pressure between 5 and 50 MPa) were used to study the crystallization kinetics of plagioclase in hydrous high-K basaltic melts as afunction of pressure, effective undercooling (ΔTeff) and time. Single-step decompression causes water exsolution and a consequent increase in the plagioclase liquidus, thus imposing an effective undercooling (∆Teff), accompanied by increased melt viscosity. Here, we show that the decompression process acts directly on viscosity and thermodynamic energy barriers (such as interfacial-free energy), controlling the nucleation process and favoring the formation of homogeneous nuclei also at high pressure (low effective undercoolings). In fact, this study shows that similar crystal number densities (Na) can be obtained both at low and high pressure (between 5 and 50 MPa), whereas crystal growth processes are favored at low pressures (5–10 MPa). The main evidence of this study is that the crystallization of plagioclase in decompressed high-K basalts is more rapid than that in rhyolitic melts on similar timescales. The onset of the crystallization process during experiments was characterized by an initial nucleation event within the first hour of the experiment, which produced the largest amount of plagioclase. This nucleation event, at short experimental duration, can produce a dramatic change in crystal number density (Na) and crystal fraction (φ), triggering a significant textural evolution in only 1 h. In natural systems, this may affect the magma rheology and eruptive dynamics on very short time scales.
    Description: MIUR, PRIN 2009, FAR2012 funds to M.R. Carroll.
    Description: Published
    Description: 55
    Description: 4V. Dinamica dei processi pre-eruttivi
    Description: JCR Journal
    Keywords: Plagioclase ; Nucleation rate ; Growth rate ; Basaltic melts ; Decompression ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
    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)
    Type: article
    Format: 1029893 bytes
    Format: application/pdf
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  • 5
    Publication Date: 2014-10-07
    Description: In the late 1990s, both German and Norwegian scientists established time-series transects in the waters surrounding Svalbard. While Norwegian research focussed traditionally on the water column of the inner Kongsfjord to the shelf break, the Alfred Wegener Institute for Polar and Marine Research (AWI) concentrated on the nearby bottom communities between 1000 and 5500m water depth (HAUSGARTEN). In 2008, the Norwegian oil company StatoilHydro funded a new project called KongHau within the scope of the EU-Project HERMES. The main goal of KongHau is to connect the Kongsfjord and HAUSGARTEN bathymetric transects. In a complementary approach, researchers from the Norwegian ARCTOS network have thus begun to sample the pelagic environment at selected HAUSGARTEN stations while AWI-scientists explore the seafloor at selected Kongsfjord stations to characterise the bottom communities. Our novel approach integrates existing and new data from different compartments of the ecosystem. This enables us to adapt and apply existing models on marginal ice zone pelagic-benthic interactions in shallow waters to the HAUSGARTEN data set. It also allows us to assess Arctic pelagic and benthic ecosystem changes in relation to climate factors such as sea ice, hydrography, NAO and AO indices.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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  • 6
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 57 (1935), S. 780-781 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 57 (1935), S. 2631-2641 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Development genes and evolution 189 (1980), S. 1-15 
    ISSN: 1432-041X
    Keywords: Cell line ; Drosophila ; Ecdysone ; Ecdysterone ; Hormones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Cells of the line Kc, derived fromDrosophila melanogaster embryos, extend long processes when exposed to ecdysteroid hormones. We have devised a quantitative assay for this morphological response, using the subline Kc-H. The assay was used to characterize the conditions required for the response. A halfmaximal response is elicited by approximately 10−8M 20-hydroxyecdysone; the response is saturated by 10−7M 20-hydroxyecdysone, which causes detectable elongation within a few hours, and a maximal response after 2–3 days. The response occurs substantially normally in the absence of serum, during growth in suspension, and in over-crowded cultures. It is not elicited by cyclic nucleotides, vertebrate growth factors, or a variety of other non-ecdysteroid reagents. Of 60 ecdysteroid compounds tested, only those which were active in other insect test systems elicited the response, and the concentrations required were approximately proportional to the concentrations active in other in vitro systems. We conclude that the response of Kc cells to 20-hydroxyecdysone retains basic features of the ecdysteroid response of intact tissues and therefore that Kc cells are a useful model system for studying ecdysteroid action.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-1211
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Segregation of the complement component, C4, was analyzed in six families that each included an individual who inherited an HLA haplotype where a crossover event had occurred in the region between HLA-B and HLA-DR. Two cDNA clones corresponding to the C4 gene were utilized as probes in Southern blot analysis of DNA from members of each family. Restriction fragment length polymorphisms (RFLP) were observed and were assigned to haplotypes. In one family RFLP, hybridizing with the C4 probes, segregrated with HLA-B, and in four families RFLP segregated with HLA-DR; one family was not informative in this respect. These analyses have made it possible to localize the genes for C4 between HLA-B and HLA-DR by molecular genotyping and to characterize three different genomic configurations of C4 genes by limited restriction mapping.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary DiGeorge syndrome (DGS) is a human developmental defect of the structures derived from the third and fourth pharyngeal pouches. It apparently arises due to deletion of 22q11. We describe a strategy for the isolation of DNA probes for this region. A deleted chromosome 22, which includes 22q11, was flow-sorted from a lymphoblastoid cell line of a patient with cat eye syndrome and used as the source of DNA. A DNA library was constructed from this chromosome by cloning into the EcoR1 site of the vector Lambda gt10. Inserts were amplified by PCR and mapped using a somatic cell hybrid panel of this region. Out of 32 probes, 14 were mapped to 22q11. These probes were further sublocalised within the region by dosage analysis of DGS patients, and by the use of two new hybrid cell lines which we have produced from DGS patients. One of these lines (7939B662) contains the altered human chromosome segregated from its normal homologue. This chromosome 22 contains an interstitial deletion in 22q11, and will be useful for localising further probes to the DGS region.
    Type of Medium: Electronic Resource
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