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  • 1
    Electronic Resource
    Electronic Resource
    Transport and deposition of pyroclastic density currents over an inhabited area: the deposits of the AD 79 eruption of Vesuvius at Herculaneum, Italy (2002)
    Oxford, UK : Blackwell Science Ltd
    Sedimentology 49 (2002), S. 0 
    Details
    ISSN: 1365-3091
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Geological and volcanological studies were performed in the Herculaneum excavations, 7 km west of Vesuvius, Italy, to reconstruct the main features of the pyroclastic density currents and the temporal sequence of the ad 79 eruptive events that destroyed and buried the town. The identification of two distinctive marker beds allows correlation of these deposits with the better-known sequences to the south of Vesuvius, along the dispersal axis of the Plinian fall deposit. Detailed observations from stratigraphic sections show that the pyroclastic density current deposits are characterized by several sedimentary facies, each recording different depositional and emplacement mechanisms. Facies analysis reveals both lateral and vertical variations from massive to stratified deposits, which can be related to the combined effects of flow dynamics and local irregularities of the substratum at centimetre or metre scales. These topographic irregularities enhanced turbulence and allowed rapid transition from non-turbulent to turbulent transport within the flow. Fabric data from these deposits, both from roof tile orientations and anisotropy magnetic susceptibility (AMS) analyses carried out on some of the pyroclastic deposits, suggest that the pyroclastic density currents were strongly affected by the presence of buildings. These obstacles probably caused deflection and separation of flows into multiple lobes that moved in different directions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3091.2002.00483.x
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  • 2
    Electronic Resource
    Electronic Resource
    Matrix effects in the plameless atomic absorption determination of trace amounts of barium in silicates
    Amsterdam : Elsevier
    Analytica Chimica Acta 82 (1976), S. 415-420 
    Details
    ISSN: 0003-2670
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/S0003-2670(01)84619-5
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  • 3
    Electronic Resource
    Electronic Resource
    Isotopic ratio and concentration of sulfur in the undersaturated alkaline magmas of Vulture Volcano (Italy) (1994)
    Springer
    Bulletin of volcanology 56 (1994), S. 487-492 
    Details
    ISSN: 1432-0819
    Keywords: Key words Sulphur isotopes ; alkaline magmas magma degassing ; magma contamination ; Vulture Volcano ; Italy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Both the δ34S value and the total S content of products from Vulture Volcano, Italy are mainly controlled by the separation of S gases, predominantly SO2, from high f O2 magmas containing S predominantly as SO2– 4. The addition of evaporites to such magmas appears to be a relatively uncommon and limited phenomenon. The total S content of the most primitive product of Vulture Volcano (5600 mg/kg) is very high. The high δ34S value of 4ö indicates an origin through the partial melting of a mantle containing high S, enriched in 34S of unknown origin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004450050057
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  • 4
    Electronic Resource
    Electronic Resource
    Fluid geochemistry of Montserrat Island, West Indies (1996)
    Springer
    Bulletin of volcanology 58 (1996), S. 380-392 
    Details
    ISSN: 1432-0819
    Keywords: Key words Montserrat Island ; Soufrière Hills Volcano ; Fluid geochemistry ; Hydrothermal fluids ; Magmatic fluids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  Two geochemical surveys carried out in March 1991 and September 1992 revealed the existence of a hydrothermal system in the southern portion of Montserrat Island, below Soufrière Hills Volcano. This conclusion is supported by the presence of: (a) the thermal springs of Plymouth which are fed by deep Na–Cl waters (Cl concentration ∼25 000 mg/kg, temperature ca. 250  °C) mixed with shallow steam-heated waters; (b) the four fumarolic fields of Galway's Soufrière, Gages Upper Soufrière, Gages Lower Soufrière, and Tar River Soufrière, where acid to neutral, steam-heated waters are present together with several fumarolic vents, discharging vapors formed through boiling of hydrothermal aqueous solutions. Involvement of magmatic fluids in the recharge of the hydrothermal aquifers is suggested by: (a) the high 3He/4He ratios of fumarolic fluids, i.e., 8.2 RA at Galway's Soufrière and 5.9 RA at Gages Lower Soufrière; (b) the δD and δ18O values of Na–Cl thermal springs and steam condensates, indicating the involvement of arc-type magmatic water in the formation of deep geothermal liquids; and (c) the CH4/CO2 ratios of fumarolic fluids, which are lower than expected for equilibrium with the FeO–FeO1.5 hydrothermal rock buffer, but being shifted towards the SO2–H2S magmatic gas buffer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004450050146
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  • 5
    Electronic Resource
    Electronic Resource
    Isotopic ratio and concentration of sulfur in the undersaturated alkaline magmas of Vulture Volcano (Italy) (1994)
    Springer
    Bulletin of volcanology 56 (1994), S. 487-492 
    Details
    ISSN: 1432-0819
    Keywords: Sulphur isotopes ; alkaline magmas magma degassing ; magma contamination ; Vulture Volcano, Italy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Both the δ34 value and the total S content of products from Vulture Volcano, Italy are mainly controlled by the separation of S gases, predominantly SO2, from high f O2magmas containing S predominantly as SO 2- 4 . The addition of evaporites to such magmas appears to be a relatively uncommon and limited phenomenon. The total S content of the most primitive product of Vulture Volcano (5600 mg/kg) is very high. The high δ34S value of 4‰ indicates an origin through the partial melting of a mantle containing high S, enriched in 34S of unknown origin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00302829
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  • 6
    Electronic Resource
    Electronic Resource
    Origin of the fumarolic fluids of Vulcano Island, Italy and implications for volcanic surveillance (1995)
    Springer
    Bulletin of volcanology 57 (1995), S. 99-110 
    Details
    ISSN: 1432-0819
    Keywords: Fumaroles ; Fluid chemistry ; δD value ; δ18O value ; Volcanic surveillance ; Vulcano Island
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Variations in δD and δ18O values with H2O contents and outlet temperatures indicate that the fumaroles of La Fossa crater have discharged mixtures of magmatic water and marine hydrothermal water, since 1979. The contribution of meteoric water was low in the period 1979–1982 and very low afterwards. The δ18O values of the marine-hydrothermal component of +5 to +7.2‰ are due to isotopic exchange with the 18O-rich silicates of the rocks under high-temperature and low-permeability conditions. The δ18O value of the magmatic end-member is generally +3.5 to +4.3‰, although values as high as +5.5 to +6.5‰ were reached in the summer of 1988, when magma degassing appears to have extended into the core of the magma body. The δD values of the end-member were close to -20‰, typical of andesitic waters. Both the isotopic values and chemical data strongly support a ‘dry’ model, consisting of a central magmatic gas column and a surrounding hydrothermal envelope, in which marine hydrothermal brines move along limited fracture zones to undergo total evaporation on approaching the conduits of magmatic fluids. The vents at the eastern and western boundaries of the fumarolic field are fed by fluids whose pressure is governed by the coexistence of vapor, liquid and halite, giving rise to a high risk of phreato magmatic explosions, should magma penetrate into these wet environments. Most La Fossa eruptions were triggered by an initial hydrothermal blast and continued with a series of phreatomagmatic explosions. The fluids discharged by the Forgia Vecchia fumaroles are mixed with meteoric water, which is largely evaporated, although subordinate loss of condensed steam may be responsible for scrubbing most of the acidic gas species. The temperatures and pressures, and the risk of a sudden pressure increase, are low. A boiling hydrothermal aquifer at 230° C is present underneath the Baia di Levante beach. This area has a minor risk of hydrothermal explosions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00301400
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  • 7
    Electronic Resource
    Electronic Resource
    The gas/steam ratio as indicator of heat transfer at the Solfatara fumaroles, Phlegraean Fields (Italy) (1984)
    Springer
    Bulletin of volcanology 47 (1984), S. 295-302 
    Details
    ISSN: 1432-0819
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract A simple geochemical model of Solfatara, Phlegraean Fields (Italy), is proposed on the basis of gas composition and temperature at the surface. Data on the Solfatara fumaroles have been collected since 1979 within the framework of a geochemical monitoring for the surveillance of the Phlegraean volcanic system. Surface manifestations of Solfatara are likely to be fed through isoenthalpic expansion of dry steam, which separates from a geothermal liquid in an intensively fractured zone at about 236°C. This value is consistent both with gas composition and surface temperature. The gas/steam ratio appears to be the most effective parameter to detect changes of heat flow at depth. Actually a remarkable decrease in the gas/steam ratio has been observed since 1981, while the gas composition and the temperature did not change significantly. These facts suggest increased heat flow at depth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01961560
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  • 8
    Electronic Resource
    Electronic Resource
    Contrast-enhanced three-dimensional MR angiography in the assessment of subclavian artery diseases (2000)
    Springer
    European radiology 10 (2000), S. 1737-1744 
    Details
    ISSN: 1432-1084
    Keywords: Key words: MR contrast enhancement ; MR angiography ; MRA subclavian artery ; Comparative study
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The purpose of this prospective study was to determine the potential diagnostic value of 3D breath-hold contrast-enhanced MRA (CEMRA) in the evaluation of subclavian artery pathology, and to compare CEMRA and digital subtraction angiography (DSA) findings. The study group included 50 patients with suspicion of subclavian artery pathology: 40 suspected steno-occlusive disease and 10 different vascular anomalies. The MRA examinations were performed on a 1.5-T system using fast 3D sequences. A fixed dose of 40 ml Gd-DTPA was administered at 2 ml/s after previous bolus tracking. Images were analyzed to assess: subclavian depiction; luminal changes; collateral branches; and feeders of arterial venous malformations (AVM). A multireader blinded fashion was used. The CEMRA revealed an optimal agreement with DSA findings in the different types of diseases. Sensitivity and specificity were 90 and 95 %, respectively, in detecting steno-occlusive disease (including functional and arteritic stenoses), and 100 and 100 %, respectively, in cases of vascular anomalies (dilation, kinking, anomalous origin and AVM). Contrast-enhanced MRA can be proposed as a non-invasive, robust technique for imaging subclavian pathologies with high diagnostic performance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003300000454
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  • 9
    Electronic Resource
    Electronic Resource
    Pseudoaneurysm of the abdominal aorta: evaluation with virtual angioscopy of spiral-CT data sets (1999)
    Springer
    European radiology 9 (1999), S. 1227-1230 
    Details
    ISSN: 1432-1084
    Keywords: Key words: Virtual images ; Helical CT ; Image processing ; Aorta ; Grafts and prostheses ; Rupture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. We describe a case of graft-related pseudoaneurysm of the abdominal aorta evaluated with spiral CT and DSA. Spiral CT data sets were processed to obtain surface-rendered internal views (virtual angioscopy, VA) of the graft and the pseudoaneurysm, and to demonstrate from inside the lumen the site of dehiscence. A jet flow phenomenon inside the pseudoaneurysm was observed at DSA. Spiral-CT axial images, multiplanar volume reconstructions with maximum intensity projections, and shaded surface display showed the site of rupture. The VA findings were: (a) from inside the graft lumen, the evidence of a communication canal between the graft and the pseudoaneurysm; and (b) from inside the pseudoaneurysm, the presence of a jet flow. The VA findings showed good correlation with those obtained with the other imaging techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003300050823
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  • 10
    Electronic Resource
    Electronic Resource
    Evolution of fumarolic gases — boundary conditions set by measured parameters: case study at Vulcano, Italy (1988)
    Springer
    Bulletin of volcanology 50 (1988), S. 71-85 
    Details
    ISSN: 1432-0819
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Physical, chemical and isotopic parameters were measured in fumaroles at the Vulcano crater and in drowned fumaroles near the beach. The data were used to define boundary conditions for possible conceptual models of the system.Crater fumaroles: time variations of CO2 and SO2 concentrations indicate mixing of saline gas-rich water with local fresh water. Cl/Br ratios of 300– 400 favour sea-water as a major source for Cl, Brand part of the water in the fumaroles. Cl concentrations and δD values revealed, independently, amixing of 0.75 sea-water with 0.25 local freshwaterin furmarole F-5 during September 1982.Patterns of parameter correlation and mass balances reveal that CO2, S, NH3 and B originate from sources other than sea water. The CO2 value of δ13C = − 2%o favours, at least partial, origin from decomposition of sedimentary rocks rather than mantle-derived material. Radiogenic4He(1.3 × lO−3 ccSTP/g water) and radiogenic40Ar(10.6 × 10−4 ccSTP/g water) are observed, (4He/40Ar)radiogenic = 1.2, well in the range of values observed in geothermal systems.Drowned fumaroles: strongly bubbling gas at a pond and at the beachappears to have the same origin and initial compositionas the crater fumaroles (2 km away). The fumarolic gas is modified by depletion of the reactive gases, caused by dissolution in shallow-water. Atmospheric Ne, Ar, Kr and Xe are addeden route, some radiogenic He and Ar are maintained. The Vulcano system seems to be strongly influenced by the contribution of sea-water and decomposition of sedimentary rocks. Evidence of magmatic contributions is mainly derived from heat.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01275170
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