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  • 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry  (29)
  • Elsevier  (29)
  • Essen : Verl. Glückauf
  • Krefeld : Geologischer Dienst Nordhein-Westfalen
  • 2005-2009  (29)
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Keywords
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Year
  • 1
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    Helium isotopes in hydrothermal volcanic fluids of the Azores Archipelago (2009)
    Elsevier
    Details
    Publication Date: 2021-06-25
    Description: We present the first helium isotope data for thermal waters and gas emissions on the islands of Terceira, Graciosa, Faial, Pico and Flores, as well as new data for Sao Miguel. The results allow us to track current mantle degassing associated with the Azores hot spot, to delineate its spatial distribution and to discuss its possible origin. As a general rule, we find that free gases tend to display somewhat higher 3He/4He ratio than groundwaters.We argue that this difference is likely due to radiogenic helium inputs to aquifers duringwater– rock interactions and, therefore, that gas phases are the fluid carriers with the most representative of mantle source signature. The measured 3He/4He ratios (normalized to the air ratio, Ra) range from lower-than-MORB values (5.23–6.07 Ra) on central Sao Miguel, to MORB values on Faial (8.53 Ra) and Flores (8.04 Ra) – located on either side of the Mid-Atlantic Ridge – and to plume-type values on Graciosa (11.2 Ra) and Terceira (13.5 Ra) where free gases also display ten times higher-than-MORB CO2/3He ratios (1.8–2.6×1010). Such a wide He isotopic range and its spatial distribution corroborate with available data for volcanic rocks, indicating that plume's head presently underlies the central part of the archipelago. The plume-type 3He/4He ratios on Terceira and Graciosa agree with geochemical and seismic evidence of a deep-rooted mantle plume feeding the Azores hot spot. Our finding that high 3He/4He ratios correspond to low 3He concentrations and high (arctype) CO2/3He values exclude a simple plume supply of 3He-rich primitive mantle. Instead, the simultaneity of both elevated CO2/3He and 3He/4He ratios is best explained by a 3He-rich contribution from the lower mantle diluted in a CO2-rich feeding plume that contains a recycled altered oceanic plate component. The alternative possibility of an enhanced time-integrated 3He/(U+Th) ratio in the Azores plume due to a greater compatibility of helium relative to U and Th during melting events is difficult to reconcile with the enriched pattern of volcanic rocks from the central islands. In any case, the Azores plume should derive from a mantle reservoir that could escape convective homogenization for a very long period of time, in agreement with subchondritic osmium isotopic ratios in volcanic rocks from the central islands of the archipelago.
    Description: Published
    Description: 70−80
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: hydrothemal fluids ; helium isotopes ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
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    Mercury concentration, speciation and budget in volcanic aquifers: Italy and Guadeloupe (Lesser Antilles) (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Quantifying the contribution of volcanism to global mercury (Hg) emissions is important to understand the pathways and the mechanisms of Hg cycling through the Earth's geochemical reservoirs and to assess its environmental impacts. While previous studies have suggested that degassing volcanoes might contribute importantly to the atmospheric budget of mercury, little is known about the amount and behaviour of Hg in volcanic aquifers. Here we report on detailed investigations of both the content and the speciation of mercury in aquifers of active volcanoes in Italy and Guadeloupe Island (Lesser Antilles). In the studied groundwaters, total Hg (THg) concentrations range from 10 to 500 ng/l and are lower than the 1000 ng/l threshold value for human health protection fixed by the World Health Organization [WHO (1993): WHO Guidelines for Drinking Water Quality- http://www.who.int/water_sanitation_health/GDWQ/index.htlm]. Positive co-variations of (THg) with sulphate indicate that Hg-SO4-rich acid groundwaters receive a direct input of magmatic/hydrothermal gases carrying mercury as Hg0 (gas). Increasing THg in a volcanic aquifer could thus be a sensitive tracer of magmatic gas input prior to an eruption. Since the complex behaviour and toxicity of mercury in waters depend on its chemical speciation, we carefully determined the different aqueous forms of this element in our samples.We find that dissolved elemental Hg0 (aq) and particulate-bound Hg (HgP) widely prevail in volcanic aquifers, in proportions that highlight the efficiency of Hg adsorption onto colloidal particles. Moreover, we observe that dissolved Hg0 aq and Hg(II) forms coexist in comparable amount in most of the waters, in stark contrast to the results of thermodynamic equilibrium modelling. Therefore, chemical equilibrium between dissolved mercury species in volcanic waters is either prevented by natural kinetic effects or not preserved in collected waters due to sampling/storage artefacts. Finally, we provide a first quantitative comparison of the relative intensity of aqueous transport and atmospheric emissions of mercury at Mount Etna, a very active basaltic volcano.
    Description: Published
    Description: 96-106
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: reserved
    Keywords: speciation ; volcanic aquifers ; total and dissolved mercury ; mercury cycling ; volatile budget ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 3
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    Effects of soil gas permeability and recirculation flux on soil CO2 flux measurements performed using a closed dynamic accumulation chamber (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Dynamic accumulation chamber methods have been extensively used to estimate the total output of CO2 released from active volcanic area. In order to asses the performance and reliability of a closed dynamic system several tests were carried out with different soil permeabilities and soil CO2 fluxes. A special device was used to create a constant one-dimensional CO2 flux through a soil column with a known permeability. Three permeabilities were investigated, ranging between 3.6 × 10− 2 and 3.5 × 10 μm2, as were several CO2 fluxes (ranging between 1.1 × 10− 6 and 6.3 × 10− 5 kg m− 2 s− 1). The results highlight that the accuracy of soil CO2 flux measurements strictly depends on the soil gas permeability and the soil CO2 flux regimen. Generally chamber measurements underestimate CO2 fluxes at low soil permeability and low soil CO2 fluxes, whereas appreciable overestimations occur for high permeability soil, especially for high soil CO2 fluxes. Other tests carried out with different settings for the measurement device, such as the chamber volume and the flux of the pump used to recirculate air through the chamber and the gas analyzer (recirculation flux), revealed a strong dependence of the closed dynamic chamber measurements on the recirculation flux. Low recirculation fluxes (0.2–0.4 l min− 1) decreased the performance of the measurement system, causing underestimations of the actual soil CO2 flux, whereas higher values (0.6–1.0 l min− 1) resulted in overestimations, especially for elevated soil CO2 fluxes. An empirical equation was deduced to allow accumulation chamber fluxes to be calculated very accurately based on soil gas permeabilities measured in the field.
    Description: Published
    Description: 387-393
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: reserved
    Keywords: Soil CO2 flux measuraments ; Closed dynamic chamber ; soil gas permeability ; 04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 4
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    Methane fluxes from the soils in active volcanic areas: the case of Pantelleria Island (Italy) (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Methane, the most abundant hydrocarbon in the atmosphere, plays an important role in the Earth’s atmospheric chemistry and radiative balance being the second most important greenhouse gas after CO2. Methane is released to the atmosphere by a wide number of sources, both natural and anthropogenic, with the latter being twice as large as the former (Kvenvolden and Rogers, 2005). It has recently been established that significant amounts of geological methane, produced within the Earth’s crust, are currently released naturally into the atmosphere (Etiope, 2004). Among natural sources the volcanic/geothermal emissions are probably the least constrained. Recent estimations for volcanic and geothermal systems in Europe (Etiope et al. 2007) gave a rather large provisional range (4-16 kt/a) that claims for much more field measurements in order to widen the current database and decrease the present uncertainties. Pantelleria is an active volcanic complex, at present in quiescent status, hosting a high enthalpy geothermal system. Explorative geothermal wells tapped an exploitable water-dominated reservoir at 600-800 m depth with maximum measured temperatures of 250 °C. While some data are available on diffuse CO2 fluxes, data on CH4 are available only for fumarolic fluids. In the present study we measured CH4 fluxes in the area of Favara Grande characterized by intense diffuse degassing and widespread signs of geothermal activity (fumaroles, steaming grounds and large zones devoid of vegetation). Values range from negative (-43 to 0 mgCH4 m2 day), typical of soils with methanotrophic activity, up to 3500 mgCH4 m2 day in the most thermalized area. The preliminary estimate of the methane release from the area of Favara Grande is about 2.5 t/a. Extrapolation to the whole volcanic/geothermal system of Pantelleria gives about 10 t/a.
    Description: Published
    Description: Davos, Switzerland
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: open
    Keywords: soil gases ; methane output ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Poster session
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  • 5
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    The evolution of a dynamic geological system: the support of a GIS for geochemicd measurements at the fumarole field of Vulcano, Italy (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The island of Vulcano (Aeolian arc, Southern Italy) has displayed several periods of volcanic unrest since the end of the last eruption (1890). We report here results obtained from a long-term survey concerning variations of both the steam output and the exhaling surface area at the sun~mit crater fumarolic field of La Fossa. The field measurements analysed in a Geographiciil Information System (GIS: show a highly dynamic volcanic system in which deep variations in the geochemishy and the temperature of the released fluids were accompanied by fluctuations in the mass output of steam and the topography of the crater field. The use of a GIS facilitated digitized reconstructions of maps of the crater field in addition to analysis (of the steam flux data. The furnarolic field expanded its surface area from 50 m2 in 1983 to more than 2400 m* in 1995, accompanied by an increase in steam output from 152 to about 1400 tonnes per day. The possibility that the observed phenomena are related to volcano-tectonic activity and to magma uprising is taken into consideration.
    Description: Published
    Description: 253-263
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: volcanic surveillance ; Steam output ; tectonic lines ; flux ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
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    Geochemical evaluation of observed changes in volcanic activity during the 2007 eruption at Stromboli (Italy) (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: On February 27, 2007 a new eruption started at Stromboli that lasted until April 2 and included a paroxysmal explosion on March 15. Geochemical monitoring carried out over several years revealed some appreciable variations that preceded both the eruption onset and the explosion. The carbon dioxide (CO2) flux from the soil at Pizzo Sopra La Fossa markedly increased a few days before the eruption onset, and continued during lava effusion to reach its maximum value (at 90,000 g m−2 d−1) a few days before the paroxysm. Almost contemporarily, the δ13CCO2 of the SC5 fumarole located in the summit area increased markedly, peaking just before the explosion (δ13CCO2~−1.8‰). Following the paroxysm, helium (He) isotopes measured in the gases dissolved in the basal thermal aquifer sharply increased. Almost contemporarily, the automatic station of CO2 flux recorded an anomalous degassing rate. Also temperatures and the vertical thermal gradient, which had been measured since November 2006 in the soil at Pizzo Sopra La Fossa, showed appreciable variabilities that lasted until the end of the eruption. The geochemical variations indicated the degassing of a new batch of volatile-rich magma that preceded and probably fed the paroxysm. The anomalous 3He/4He ratio suggested that the ascent of a second batch of volatile-rich magma toward the surface was probably responsible of the resumption of the ordinary activity. A comparison with the geochemical variations observed during the 2002–2003 eruption indicated that the 2007 eruption was less energetic.
    Description: Published
    Description: 246-254
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: geochemistry ; eruption ; dissolved gases ; Stromboli ; volcanic activity ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.04. Chemical and biological::03.04.03. Chemistry of waters ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
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    Hydrothermal methane fluxes from the soil at Pantelleria island (Italy) (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Chemical and isotopic analyses of the main gas manifestations of the island of Pantelleria (Italy) were used to gain insight on the origin of the released methane. Results indicate that the most probable origin is through abiogenic reactions within the hydrothermal system. Methane and CO2 flux measurements from the soils were made with the accumulation chamber method in an area of about 0.015 km2 within the main fumarolic area of the island (Favara Grande). The 23 measurements range from –34 to 3550 mg m-2 d-1 for CH4 and from 0.6 to 379 g m-2 d-1 for CO2. The relationships between CH4 and CO2 fluxes and the CH4/CO2 ratios in the gases collected between 25 and 100 cm depth provide evidence for methanotrophic processes within the soils. Methane output for the surveyed area was calculated in 2.5 t a-1 and extrapolated to about 5-10 t a-1 for the entire volcanic/hydrothermal system of the island. Previous higher estimates of the CH4 output at Pantelleria (Etiope et al., 2007 - J. Volcanol. Geotherm. Res., 165, 76 – 86) were based on soil CO2 output and CH4/CO2 ratios in fumarolic gases; the present work provides the first direct CH4 flux data and it suggests that methanotrophic activity in the soil could be substantial in reducing the CH4 emission to the atmosphere.
    Description: Published
    Description: 147-157
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: reserved
    Keywords: hydrothermal systems ; gas geochemistry ; isotope composition ; methane output ; methanotrophic consumption ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
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  • 8
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    Carbon dioxide degassing from Tuscany and Northern Latium (Italy) (2008)
    Elsevier
    Details
    Publication Date: 2021-01-07
    Description: The CO2 degassing process from a large area on the Tyrrhenian side of central Italy, probably related to the input into the upper crust of mantle fluids, was investigated in detail through the geochemical study of gas emissions and groundwater. Mass-balance calculations and carbon isotopes show that over 50% of the inorganic carbon in regional groundwater is derived from a deep source highlighting gas−liquid separation processes at depth. The deep carbonate−evaporite regional aquifer acts as the main CO2 reservoir and when total pressure of the reservoir fluid exceeds hydrostatic pressure, a free gas phase separates from the parent liquid and escapes toward the surface generating gas emissions which characterise the study area. The distribution of the CO2 flux anomalies and the location of high PCO2 springs and gas emissions suggest that the storage and the expulsion of the CO2 toward the atmosphere are controlled by the geological and structural setting of the shallow crust. The average CO2 flux and the total amount of CO2 discharged by the study area were computed using surface heat flow, enthalpy and CO2 molality of the liquid phase circulating in the deep carbonate−evaporite aquifer. The results show that the CO2 flux varies from 1×104 mol y−1 km−2 to 5×107 mol y−1 km−2, with an average value of 4.8×106 mol y−1 km−2, about five times higher than the value of 1×106 mol y−1 derived by Kerrick et al. [Kerrick, D.M., McKibben, M.A., Seward, T.M., Caldeira, K., 1995. Convective hydrothermal CO2 emission from high heat flow regions. Chem. Geol. 121, 285–293] as baseline for terrestrial CO2 emissions. The total CO2 discharged from the study area is 0.9×1011 mol y−1, confirming that Earth degassing from Tyrrhenian central Italy is a globally relevant carbon source
    Description: Published
    Description: 89–102
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: 4.5. Degassamento naturale
    Description: JCR Journal
    Description: reserved
    Keywords: Earth degassing ; carbon dioxide ; CO2 flux ; groundwater ; 04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 9
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    Low-pH waters discharging from submarine vents at Panarea Island (Aeolian Islands, southern Italy) after the 2002 gas blast: origin of hydrothermal fluids and implications for volcanic surveillance (2008)
    Elsevier
    Details
    Publication Date: 2020-12-07
    Description: A geochemical survey of thermal waters collected from submarine vents at Panarea Island (Aeolian Islands, southern Italy) was carried out from December 2002 to March 2007, in order to investigate i) the geochemical processes controlling the chemical composition of the hydrothermal fluids and ii) the possible relations between the chemical features of the hydrothermal reservoir and the activity of the magmatic system. Compositional data of the thermal water samples were integrated in a hydrological conceptual model, which describes the formation of the vent fluid by mixing of seawater, seawater concentrated by boiling, and a deep, highly-saline end-member, whose composition is regulated by water-rock interactions at relatively high temperature and shows clear clues of magmatic-related inputs. The chemical composition of concentrated seawater was assumed to be represented by that of the water sample having the highest Mg content. The composition of the deep end-member was instead calculated by extrapolation assuming a zero-Mg end-member. The Na–K–Ca geothermometer, when applied to the thermal end-member composition, indicated an equilibrium temperature of approximately 300 °C, a temperature in agreement with the results obtained by gas-geothermometry.
    Description: Published
    Description: 246-254
    Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici
    Description: JCR Journal
    Description: reserved
    Keywords: low-pH waters; shallow submarine hydrothermal springs; Panarea Island ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry
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  • 10
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    Hydrochemical dynamics of the “lake–spring” system in the crater of El Chichón volcano (Chiapas, Mexico) (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: El Chichón volcano (Chiapas, Mexico) erupted violently in March–April 1982, breaching through the former volcano–hydrothermal system. Since then, the 1982 crater has hosted a shallow (1–3.3 m, acidic (pH ∼ 2.2) and warm (∼ 30 °C) crater lake with a strongly varying chemistry (Cl/SO4=0–79 molar ratio). The changes in crater lake chemistry and volume are not systematically related to the seasonal variation of rainfall, but rather to the activity of near-neutral geyser-like springs in the crater (Soap Pool). These Soap Pool springs are the only sources of Cl for the lake. Their geyser-like behaviour with a long-term (months to years) periodicity is due to a specific geometry of the shallow boiling aquifer beneath the lake, which is the remnant of the 1983 Cl-rich (24,000 mg/l) crater lake water. The Soap Pool springs decreased in Cl content over time. The zero-time extrapolation (1982, year of the eruption) approaches the Cl content in the initial crater lake,meanwhile the extrapolation towards the future indicates a zero-Cl content by 2009±1. This particular situation offers the opportunity to calculate mass balance and Cl budget to quantify the lake–spring system in the El Chichón crater. These calculations show that the water balance without the input of SP springs is negative, implying that the lake should disappear during the dry season. The isotopic composition of lake waters (δD and δ18O) coincide with this crater lake-SP dynamics, reflecting evaporation processes and mixing with SP geyser and meteoric water. Future dome growth, not observed yet in the post-1982 El Chichón crater, may be anticipated by changes in lake chemistry and dynamics.
    Description: Published
    Description: 237–248
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: JCR Journal
    Description: reserved
    Keywords: El Chichón volcano ; crater lake–Spring dynamics ; fluid geochemistry ; stable isotopes ; monitoring ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
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  • 11
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    Estimating thermal inflow to El Chichón crater lake using the energy-budget, chemical and isotope balance approaches (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: El Chichón crater lake appeared immediately after the 1982 catastrophic eruption in a newly formed, 1-km wide, explosive crater. During the first 2 years after the eruption the lake transformed from hot and ultraacidic caused by dissolution of magmatic gases, to a warm and less acidic lake due to a rapid “magmatic-tohydrothermal transition” — input of hydrothermal fluids and oxidation of H2S to sulfate. Chemical composition of the lake water and other thermal fluids discharging in the crater, stable isotope composition (δD and δ18O) of lake water, gas condensates and thermal waters collected in 1995–2006 were used for the mass-balance calculations (Cl, SO4 and isotopic composition) of the thermal flux from the crater floor. The calculated fluxes of thermal fluid by different mass-balance approaches become of the same order of magnitude as those derived from the energy-budget model if values of 1.9 and 2 mmol/mol are taken for the catchment coefficient and the average H2S concentration in the hydrothermal vapors, respectively. The total heat power from the crater is estimated to be between 35 and 60 MW and the CO2 flux is not higher than 150 t/day or ~200 gm−2 day−1.
    Description: Published
    Description: 472-481
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: JCR Journal
    Description: reserved
    Keywords: El Chichón ; crater lake ; mass-energy budget ; CO2 flux ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data ; 05. General::05.02. Data dissemination::05.02.04. Hydrogeological data
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  • 12
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    Major and trace element geochemistry of neutral and acidic thermal springs at El Chichón volcano, Mexico Implications for monitoring of the volcanic activity (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Four groups of thermal springs with temperatures from 50 to 80 °C are located on the S–SW–W slopes of El Chichón volcano, a composite dome-tephra edifice, which exploded in 1982 with a 1 km wide, 160 m deep crater left. Very dynamic thermal activity inside the crater (variations in chemistry and migration of pools and fumaroles, drastic changes in the crater lake volume and chemistry) contrasts with the stable behavior of the flank hot springs during the time of observations (1974–2005). All known groups of hot springs are located on the contact of the basement and volcanic edifice, and only on the W–SW–S slopes of the volcano at almost same elevations 600–650 m asl and less than 3 km of direct distance from the crater. Three groups of near-neutral (pH≈6) springs at SW–S slopes have the total thermal water outflow rate higher than 300 l/s and are similar in composition. The fourth and farthest group on the western slope discharges acidic (pH≈2) saline (10 g/kg of Cl) water with a much lower outflow rate (b10 l/s). Water–rock interaction modeling of main types of the El Chichón thermal waters using regular log Q/K graphs (saturation indices vs temperature) showed maximum equilibrium temperature slightly higher than 200 °C. Acidic waters are equilibrated with some clay minerals at about 120 °C. Three main sources of the salinity of thermal water are suggested on the basis of mixing plots and isotopic data: a magmatic source for CO2, boron, sulfur and a limited part of Cl; volcanic rock source for the major cations and trace elements; the oil-bearing evaporitic basement source (oil-field brine?) for NaCl, Br, a part of Ca and some trace elements. All flank thermal springs end up in the river Rio Magdalena that has a variable seasonal flow rates from 4 to 20 m3/s. Any changes in the chemistry of springs must notably change the composition of the streams draining hot springs and eventually, Rio Magdalena. A monthly geochemical monitoring of Rio Magdalena and streams draining main hot springs would be a useful tool for surveying the activity of the volcano.
    Description: Published
    Description: 224–236
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: JCR Journal
    Description: reserved
    Keywords: volcano–hydrothermal system ; crater lake ; acidic water ; trace elements ; thermochemical modeling ; El Chichón volcano ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
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  • 13
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    Methana, the westernmost active volcanic system of the south Aegean arc (Greece): insight from fluids geochemistry (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: An extensive geochemical survey of the fluids released by the volcanic/geothermal system of Methana was undertaken. Gases were characterized based on the chemical and isotopic [helium (He) and carbon (C)] analysis of 27 samples. Carbon dioxide soil gas concentration and fluxes were measured at 179 sampling sites throughout the peninsula. Forty samples of thermal and cold groundwaters were also sampled and analysed to characterize the geochemistry of the aquifers. Gases of hydrothermal origin gave a preliminary geothermometric estimate of about 210 °C. The He-isotope composition indicated mantle contributions of up to 40%, and the C-isotope composition of CO2 indicated that it predominantly (〉90%) originated from limestone decomposition. The groundwater composition was suggestive of mixing between meteoric and hydrothermally modified sea-water endmembers and water–rock interaction processes limited to simple rock dissolution driven by an increased endogenous CO2 content. All of the thermal manifestations and anomalous degassing areas, although of limited extent, were spatially correlated with the main active tectonic system of the area. The total CO2 output of the volcanic system has been preliminary estimated to be less than 0.05 kg s–1. Although this value is very low compared to those of other volcanic systems, anomalous CO2 degassing at Methana – which is currently restricted to limited areas and at present is the only volcanic risk of the peninsula – is a potential gas hazard that warrants further assessment in future studies.
    Description: Published
    Description: 818-828
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Methana ; south Aegean volcanic arc ; fluids geochemistry ; soil gases ; groundwaters ; 03. Hydrosphere::03.04. Chemical and biological::03.04.03. Chemistry of waters ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 14
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    Mercury concentration, speciation and budget in volcanic aquifers: Italy and Guadeloupe (Lesser Antilles) (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Research article
    Description: Quantifying the contribution of volcanism to global mercury (Hg) emissions is important to understand the pathways and the mechanisms of Hg cycling through the Earth's geochemical reservoirs and to assess its environmental impacts. While previous studies have suggested that degassing volcanoes might contribute importantly to the atmospheric budget of mercury, little is known about the amount and behaviour of Hg in volcanic aquifers. Here we report on detailed investigations of both the content and the speciation of mercury in aquifers of active volcanoes in Italy and Guadeloupe Island (Lesser Antilles). In the studied groundwaters, total Hg (THg) concentrations range from 10 to 500 ng/l and are lower than the 1000 ng/l threshold value for human health protection fixed by the World Health Organization [WHO (1993): WHO Guidelines for Drinking Water Quality- http://www.who.int/water_sanitation_health/GDWQ/index.htlm]. Positive co-variations of (THg) with sulphate indicate that Hg-SO4-rich acid groundwaters receive a direct input of magmatic/hydrothermal gases carrying mercury as Hg0 (gas). Increasing THg in a volcanic aquifer could thus be a sensitive tracer of magmatic gas input prior to an eruption. Since the complex behaviour and toxicity of mercury in waters depend on its chemical speciation, we carefully determined the different aqueous forms of this element in our samples.We find that dissolved elemental Hg0 (aq) and particulate-bound Hg (HgP) widely prevail in volcanic aquifers, in proportions that highlight the efficiency of Hg adsorption onto colloidal particles. Moreover, we observe that dissolved Hg0 aq and Hg(II) forms coexist in comparable amount in most of the waters, in stark contrast to the results of thermodynamic equilibrium modelling. Therefore, chemical equilibrium between dissolved mercury species in volcanic waters is either prevented by natural kinetic effects or not preserved in collected waters due to sampling/storage artefacts. Finally, we provide a first quantitative comparison of the relative intensity of aqueous transport and atmospheric emissions of mercury at Mount Etna, a very active basaltic volcano.
    Description: In press
    Description: 4.5. Degassamento naturale
    Description: JCR Journal
    Description: open
    Keywords: Fluid geochemistry ; volcanic mercury ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry
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  • 15
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    Carbon isotopic composition of soil CO2 efflux, a powerful method to discriminate different sources feeding soil CO2 degassing in volcanic-hydrothermal areas (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: A new method combining measurements of soil CO2 flux and determinations of the carbon isotopic composition of soil CO2 efflux was developed in order to qualitatively and quantitatively characterise the CO2 source feeding the soil CO2 diffuse degassing. The method was tested in March 2007 at the Solfatara of Pozzuoli volcano degassing area (Naples, Italy) where more than 300 measurements of soil CO2 flux and determinations of the carbon isotopic composition of soil CO2 efflux were performed, surveying Solfatara crater and its surroundings. The wide range of CO2 flux and CO2 isotopic composition values (from 8.4 g m−2 d−1 to 28,834 g m−2 d−1, and from 0.73‰ to −33.54‰, respectively), together with their statistical distributions suggests the occurrence of multiple CO2 sources feeding soil degassing. The combined interpretation of flux and isotopic data allows us to identify and characterise two distinct gas sources: a hydrothermal and a biogenic source. The soil CO2 from the hydrothermal source is characterised by a mean δ13CCO2 of −2.3‰±0.9‰, hence close to the isotopic composition of the fumarolic CO2 (δ13CCO2=−1.48‰± 0.22‰) and by a mean CO2 flux of 2875 g m−2 d−1. The CO2 from the biogenic source is characterised by a mean δ13CCO2 of −19.4‰±2.1‰, and by a mean CO2 flux of 26 g m−2 d−1, which are both in the range of the typical values for biologic CO2 soil degassing. This reliable characterisation of the biogenic CO2 flux would not have been possible by solely applying a statistical analysis of the CO2 flux values, which is commonly applied in volcanological studies for the partitioning between background fluxes and anomalous CO2 fluxes. A map of the Solfatara diffuse degassing structure was derived from the estimated threshold for the biogenic CO2 flux, highlighting that soil degassing of hydrothermal CO2 mixed in different proportion with biogenic CO2 occurs over a large area (~0.8 km2), which extends over the inner part of the Solfatara crater as well as the eastern periphery, corresponding with a NW–SE fault system. The presented method and data analysis are important means of surveillance of the volcanic activity.
    Description: Published
    Description: 372–379
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: 4.5. Degassamento naturale
    Description: JCR Journal
    Description: reserved
    Keywords: CO2 soil degassing ; CO2 flux ; carbon dioxide ; carbon isotopes ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
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  • 16
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    Geochemical and biochemical evidence of lake overturn and fish kill at Lake Averno, Italy (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Lake Averno is situated in the homonymous crater in the northwestern sector of the Campi Flegrei active volcanic system in Campania region, Italy. In February 2005 a fish kill event was observed in the lake, prompting a geochemical survey to ascertain the possible cause. In February 2005 a geochemical survey revealed that the lake water was unstratified chemically and isotopically, presumably, as a result of lake overturn. This fish kill phenomenon was recorded at least two other times in the past. In contrast to the February 2005 results, data collected in October 2005, shows the Lake Averno to be stratified, with an oxic epilimnion (surface to 6 m) and an anoxic hypolimnion (6 m to lake bottom at about 33 m). Chemical and isotopic compositions of Lake Averno waters suggest an origin by mixing of shallow waters with a Na–Cl hydrothermal component coupled with an active evaporation process. The isotopic composition of Dissolved Inorganic Carbon, as well as the composition of the non-reactive dissolved gas species again supports the occurrence of this mixing process. Decreasing levels of SO4 and increasing levels of H2S and CH4 contents in lake water with depth, strongly suggests anaerobic bacterial processes are occurring through decomposition of organic matter under anoxic conditions in the sediment and in the water column. Sulfate reduction and methanogenesis processes coexist and play a pivotal role in the anaerobic environment of the Lake Averno. The sulfate reducing bacterial activity has been estimated in the range of 14–22 μmol m−2 day−1. Total gas pressure of dissolved gases ranges between 800 and 1400 mbar, well below the hydrostatic pressure throughout the water column, excluding the possibility, at least at the survey time, of a limnic eruption. Vertical changes in the density of lake waters indicate that overturn may be triggered by cooling of epilimnetic waters below 7 °C. This is a possible phenomenon in winter periods if atmospheric temperatures remain frosty for enough time, as occurred in February 2005. The bulk of these results strongly support the hypothesis that fish kill was caused by a series of events that began with the cooling of the epilimnetic waters with breaking of the thermal stratification, followed by lake overturn and the rise of toxic levels of H2S from the reduced waters near the lake bottom.
    Description: Published
    Description: 305–316
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: 4.5. Degassamento naturale
    Description: JCR Journal
    Description: reserved
    Keywords: lake Averno ; dissolved gases ; stable isotopes ; stable isotopes ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 17
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    Environmental impact of magmatic fluorine emission in the Mt. Etna area (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The sustained and uninterrupted plume degassing at Mount Etna volcano, Southern Italy, represents the troposphere’s most prominent natural source of fluorine. Of the ~ 200 Mg of fluorine (as HFg) emitted daily by the volcano, 1.6±2.7 Mg are deposited by wet and dry deposition. Fluorine-deposition via volcanic ash, here characterised for the first time, can be quite significant during volcanic eruptions (i.e. 60 Mg of fluorine were deposited during the 2001 eruption through volcanic ash, corresponding to ~ 85% of the total fluorine deposition). Despite the fact that these depositions are huge, the fate of the deposited fluorine and its impact on the environment are poorly understood. We herein present original data on fluorine abundance in vegetation (Castanea Sativa and Pinus Nigra) and andosoils from the volcano’s flank, in the attempt to reveal the potential impact of volcanogenic fluorine emissions. Fluorine contents in chestnut leaves and pine needles are in the range 1.8-35 µg/g and 2.1-74 µg/g respectively; they exceed the typical background concentrations in plants growing in rural areas, but fall within the lower range of typical concentrations in plants growing near high fluorine anthropogenic emission sources. The rare plume fumigations on the lower flanks of Mt Etna (distance 〉 4 km from summit craters) are probably the cause of the “undisturbed” nature of Etnean vegetation: climatic conditions, which limit the growth of vegetation on the upper regione deserta, are a natural limit to the development of more severe impacts. High fluorine contents, associated with visible symptoms, were only measured in pine needles at three sites, located near recently-active (2001 to 2003) lateral eruptive fractures. Total fluorine contents (FTOT) in the Etnean soils have a range of 112-341 µg/g, and fall within the typical range of undisturbed soils; fluorine extracted with distilled water (FH2O) have a range of 5.1 to 61 µg/g and accounts for 2-40 % of FTOT. FH2O is higher in topsoils from the eastern flank (downwind), while it decreases with depth in soil profiles and on increasing soil grain size (thereby testifying to its association with clay-mineral-rich, fine soil fractions). The fluorine adsorption capacity of the andosoils acts as a natural barrier that protects the groundwater system.
    Description: Published
    Description: 87-101
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 4.5. Degassamento naturale
    Description: JCR Journal
    Description: reserved
    Keywords: Mt. Etna ; Fluorine ; environmental volcanology ; impact of volcanic F ; soils ; vegetation ; volcanic ash ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 03. Hydrosphere::03.03. Physical::03.03.01. Air/water/earth interactions ; 04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 05. General::05.08. Risk::05.08.01. Environmental risk
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  • 18
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    Gas geochemistry as a tool to investigate the Earth's degassing through volcanic and seismic areas: The soul of the 8th International Conference on Gas Geochemistry (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Introduction of a special issue of the journal
    Description: no abstract
    Description: Published
    Description: 1-4
    Description: 4.5. Degassamento naturale
    Description: JCR Journal
    Description: reserved
    Keywords: Earth's degassing ; volcanic areas ; seismic areas ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
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  • 19
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    REE in skarn systems: A LA-ICP-MS study of garnets from the Crown Jewel gold deposit (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Metamorphic and magmatic garnets are known to fractionate REE, with generally HREE-enriched patterns, and high Lu/ Hf and Sm/Nd ratios, making them very useful as geochemical tracers and in geochronological studies. However, these garnets are typically Al-rich (pyrope, almandine, spessartine, and grossular) and little is known about garnets with a more andraditic (Fe3+) composition, as frequently found in skarn systems. This paper presents LA-ICP-MS data for garnets from the Crown Jewel Au-skarn deposit (USA), discusses the factors controlling incorporation of REE into garnets, and strengthens the potential of garnet REE geochemistry as a tool to help understand the evolution of metasomatic fluids. Garnets from the Crown Jewel deposit range from Adr30Grs70 to almost pure andradite (Adr〉99). Fe-rich garnets (Adr〉90) are isotropic, whereas Al-rich garnets deviate from cubic symmetry and are anisotropic, often showing sectorial dodecahedral twinning. All garnets are extremely LILE-depleted, Ta, Hf, and Th and reveal a positive correlation of RREE3+ with Al content. The Al-rich garnets are relatively enriched in Y, Zr, and Sc and show ‘‘typical’’ HREE-enriched and LREE-depleted patterns with small Eu anomalies. Fe-rich garnets (Adr〉90) have much lower RREE and exhibit LREE-enriched and HREE-depleted patterns, with a strong positive Eu anomaly. Incorporation of REE into garnet is in part controlled by its crystal chemistry, with REE3+ following a coupled, YAG-type substitution mechanism ð½ X2þ VIII 1 ½REE3þ VIII þ1 ½ Si4þ IV 1½Z3þ IV þ1Þ, whereas Eu2+ substitutes for X2+ cations. Thermodynamic data (e.g., Hmixing) in grossular– andradite mixtures suggest preferential incorporation of HREE in grossular and LREE in more andraditic compositions. Variations in textural and optical features and in garnet geochemistry are largely controlled by external factors, such as fluid composition, W/R ratios, mineral growth kinetics, and metasomatism dynamics, suggesting an overall system that shifts dynamically between internally and externally buffered fluid chemistry driven by fracturing. Al-rich garnets formed by diffusive metasomatism, at low W/R ratios, from host-rock buffered metasomatic fluids. Fe-rich garnets grow rapidly by advective metasomatism, at higher W/R ratios, from magmatic-derived fluids, consistent with an increase in porosity by fracturing.
    Description: Published
    Description: 185-205
    Description: 3.6. Fisica del vulcanismo
    Description: 3.8. Geofisica per l'ambiente
    Description: JCR Journal
    Description: reserved
    Keywords: A LA-ICP-MS ; Crown Jewel ; 04. Solid Earth::04.01. Earth Interior::04.01.04. Mineral physics and properties of rocks ; 04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 20
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    Evaluation of carbon isotope fractionation of soil CO2 under an advective–diffusive regimen: A tool for computing the isotopic composition of unfractionated deep source (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: A physical model based on the advective–diffusion theory was developed in order to describe the mixing between a deep gas source and the atmosphere. The model was used to predict the isotopic fractionation of carbon in soil CO2. Gas samples were collected at different depths in areas characterized by different geological settings and CO2 fluxes. The relative theoretical and experimental isotopic profiles were compared and a good agreement was found. These profiles show how the isotopic composition of CO2 changes through the upper few decimeters of soil and how the amount of the isotopic fractionation is strongly influenced by soil CO2 flux. Finally, the model was used to derive the carbon isotopic composition of unfractioned deep CO2 source for all the investigated sites
    Description: Published
    Description: 3016–3027
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: 4.5. Degassamento naturale
    Description: JCR Journal
    Description: reserved
    Keywords: Carbon isotope fractionation ; soil degassing ; gas transport ; D13C(CO2) ; 04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
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  • 21
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    The origin of the fumaroles of La Solfatara (Campi Flegrei, South Italy) (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The analysis of gaseous compositions from Solfatara (Campi Flegrei, South Italy) fumaroles since the early 1980s, clearly reveals a double thermobarometric signature. A first signature at temperatures of about 360 C was inferred by methanebased chemical–isotopic geoindicators and by the H2/Ar geothermometer. These high temperatures, close to the critical point of water, are representative of a deep zone where magmatic gases flash the hydrothermal liquid, forming a gas plume. A second signature was found to be at around 200–240 C. At these temperatures, the kinetically fast reactive species (H2 and CO) re-equilibrate in a pure vapor phase during the rise of the plume. A combination of these observations with an original interpretation of the oxygen isotopic composition of the two dominant species, i.e. H2O and CO2, shed light on the origin of fumarolic fluids by showing that effluents are mixture between fluids degassed from a magma body and the vapor generated at about 360 C by the vaporization of hydrothermal liquids. A typical ‘andesitic’ water type (dD 20&, d18O 10&) and a CO2-rich composition ðXCO2 0:4Þ has been inferred for the magmatic fluids, while for the hydrothermal component a meteoric origin and a CO2 fugacity fixed by fluid-rock reaction at high temperatures have been estimated. In the time the fraction of magmatic fluids in the fumaroles increased (up to 0.5) at each seismic and ground uplift crisis (bradyseism) which occurred at Campi Flegrei, suggesting that bradyseismic crises are triggered by periodic injections of CO2-rich magmatic fluids at the bottom of the hydrothermal system
    Description: Published
    Description: 3040-3055
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: 4.5. Degassamento naturale
    Description: JCR Journal
    Description: reserved
    Keywords: origin of the fumaroles ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 22
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    Magma dynamics at mid-ocean ridges by noble gas kinetic fractionation: Assessment of magmatic ascent rates (2006)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Despite its impact in understanding oceanic crust formation and eruptive styles of related volcanism, magma dynamics at midocean ridges are poorly known. Here, we propose a new method to assess ascent rates of mid-ocean ridge basalt (MORB) magmas,as well as their pre- and sin-eruptive dynamics. It is based on the idea that a rising magma can reach a variable degree of both CO2 supersaturation in melt and kinetic fractionation among noble gases in vesicles in relation to its ascent rate through the crust. To quantify the relationship, we have used a model of multicomponent bubble growth in MORB melts, developed by extending the single-component model of Proussevitch and Sahagian [A.A. Proussevitch, D.L. Sahagian, Dynamics and energetics of bubble growth in magmas: analytical formulation and numerical modeling, J. Geophys. Res. 103 (1998), 18223–18251.] to CO2–He–Ar gas mixtures. After proper parameterization, we have applied it to published suites of data having the required features (glasses from Pito Seamount and mid-Atlantic ridges). Our results highlight that the investigated MORB magmas display very different ranges of ascent rates: slow rises of popping rock forming-magmas that cross the crust (0.01–0.5 m/s), slightly faster rates of energetic effusions (0.1–1 m/s), up to rates of 1–10 m/s which fall on the edge between lava effusion and Hawaiian activity. Inside a single plumbing system, very dissimilar magma dynamics highlight the large differences in compressive stress of the oceanic crust on a small scale. Constraints on how the systems of ridges work, as well as the characteristics of the magmatic source, can also be obtained. Our model shows how measurements of both the dissolved gas concentration in melt and the volatile composition of vesicles in the same sample are crucial in recognizing the kinetic effects and definitively assessing magma dynamics. An effort should be made to correctly set the studied samples in the sequence of volcanic submarine deposits where they are collected. Enhanced knowledge of a number of physical properties of gas-bearing MOR magmas is also required, mainly noble gas diffusivities, to describe multicomponent bubble growth at a higher confidence level.
    Description: Published
    Description: 138-158
    Description: partially_open
    Keywords: Bubble growth ; MORB ; Noble gas ; Kinetic fractionation ; Modeling ; 04. Solid Earth::04.04. Geology::04.04.07. Rock geochemistry ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 23
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    Reply to the comment by R.M. Prol-Ledesma on ‘‘Geochemistry of fluids from submarine thermal springs at Punta de Mita, Nayarit, Mexico’’ (2006)
    Elsevier
    In:  Taran Y. A., Inguaggiato S., Marin M., and Yurova L. M. (2002) Geochemistry of fluids from submarine hot springs at Punta de Mita, Nayarit, Mexico. J. Volcanol. Geoth. Res. 115, 329-338.
    Details
    Publication Date: 2017-04-04
    Description: We thank R.M. Prol-Ledesma for her comment on the paper by Taran et al. (2002a) and the new data presented on the water composition of the Punta de Mita (PM) submarine springs. Prol-Ledesma (2003) comments refer to a supposedly wrong citation, superficial description of the geological background, incorrect method of water sampling, wrong approach for the estimation of the end-member composition, irrelevant discussion on the origin of fluids and, lastly, the using of someone else’s ideas and conclusions. In addition, she claims that our data on the fluid chemistry of the springs are not the first (original)ones. The Comment is supported by numerous references to publications by Prol-Ledesma et al. The text below follows the rubrics in the Comment.
    Description: Published
    Description: 319-322
    Description: partially_open
    Keywords: submarine springs ; hydrothermal systems ; geothermometry ; He-isotopes ; formation waters ; Jalisco Block ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 24
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    Gas hazard assessment in a densely inhabited area of Colli Albani Volcano (Cava dei Selci, Roma) (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The northwestern flank of the Colli Albani, a Quaternary volcanic complex near Rome, is characterised by high CO2 values and Rn activities in the groundwater and by the presence of zones with strong emission of gas from the soil. The most significant of these zones is Cava dei Selci where many houses are located very near to the gas emission site. The emitted gas consists mainly of CO2 (up to 98 vol) with an appreciable content of H2S (0.8). The He and C isotopic composition indicates, as for all fluids associated with the Quaternary Roman and Tuscany volcanic provinces, the presence of an upper mantle component contaminated by crustal fluids associated with subducted sediments and carbonates. An advective CO2 flux of 37 tons/day has been estimated from the gas bubbles rising to the surface in a small drainage ditch and through a stagnant water pool, present in the rainy season in a topographically low central part of the area. A CO2 soil flux survey with an accumulation chamber, carried out in February-March 2000 over a 12 000 m2 surface with 242 measurement points, gave a total (mostly conductive) flux of 61 tons/day. CO2 soil flux values vary by four orders of magnitude over a 160-m distance and by one order of magnitude over several metres. A fixed network of 114 points over 6350 m2 has been installed in order to investigate temporal flux variations. Six surveys carried out from May 2000 to June 2001 have shown large variations of the total CO2 soil flux (8/25 tons/day). The strong emission of CO2 and H2S, which are gases denser than air, produces dangerous accumulations in low areas which have caused a series of lethal accidents to animals and one to a man. The gas hazard near the houses has been assessed by continuously monitoring the CO2 and H2S concentration in the air at 75 cm from the ground by means of two automatic stations. Certain environmental parameters (wind direction and speed; atm P, T, humidity and rainfall) were also continuously recorded. At both stations, H2S and CO2 exceeded by several times the recommended concentration thresholds. The highest CO2 and H2S values were recorded always with wind speeds less than 1.5 m/s, mostly in the night hours. Our results indicate that there is a severe gas hazard for people living near the gas emission site of Cava dei Selci, and appropriate precautionary and prevention measures have been recommended both to residents and local authorities.
    Description: - GNV funded research project Gas Hazard of Colli Albani
    Description: Published
    Description: 81^94
    Description: partially_open
    Keywords: Colli Albani ; CO2 flux ; H2S ; gas hazard ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 25
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    Genesis of chlorine and sulphur in fumarolic emissions at Vulcano Island (Italy) : assessment of pH and redox conditions in the hydrothermal system (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Chlorine- and sulphur-bearing compounds in fumarole discharges of the La Fossa crater at Vulcano Island (Italy) can be modelled by a mixing process between magmatic gases and vapour from a boiling hydrothermal system. This allows estimating the compounds in both endmembers. Magma degassing cannot explain the time variation of sulphur and HCl concentrations in the deep endmember, which are more probably linked to reactions of solid phases at depth, before mixing with the hydrothermal vapours. Based on the P^T conditions and speciation of the boiling hydrothermal system below La Fossa, the HCl and Stot contents in the hydrothermal vapours were used to compute the redox conditions and pH of the aqueous solution. The results suggest that the haematite magnetite buffer controls the hydrothermal fO2 values, while the pH has increased since the end of the 1970s. The main processes affecting pH values may be linked to Na^Ca exchanges between evolved seawater, feeding the boiling hydrothermal system, and local rocks. While Na is removed from water, calcium enters the solution, undergoes hydrolysis and produces HCl,lowering the pH of the water. The increasing water^rock ratio within the hydrothermal system lowers the Ca availability, so the aqueous solution becomes less acidic. Seawater flowing towards the boiling hydrothermal brine dissolves a large quantity of pyrite along its path. In the boiling hydrothermal system, dissolved sulphur precipitates as pyrite and anhydrite, and becomes partitioned in vapour phase as H2S and SO2. These results are in agreement with the paragenesis of hydrothermal alteration minerals recovered in drilled wells at Vulcano and are also in agreement with the isotopic composition of sulphur emitted by the crater fumaroles.
    Description: Published
    Description: 137-150
    Description: partially_open
    Keywords: chlorine ; sulphur ; hydrothermal system ; genetic processes ; Vulcano Island ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Fluid circulation at Stromboli volcano (Aeolian Islands, Italy) from self-potential and CO2 surveys (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: This work addresses the study of fluid circulation of the Stromboli island using a dense coverage of self-potential (SP) and soil CO2 data. A marked difference exists between the northern flank and the other flanks of the island. The northern flank exhibits (1) a typical negative SP/altitude gradient not observed on the other flanks, and (2) higher levels of CO2. The general SP pattern suggests that the northern flank is composed of porous layers through which vadose water flows down to a basal water table, in contrast to the other flanks where impermeable layers impede the vertical flow of vadose water. In the Sciara del Fuoco and Rina Grande-Le Schicciole landslide complexes, breccias of shallow gliding planes may constitute such impermeable layers whereas elsewhere, poorly permeable, fine-grained pyroclastites or altered lava flows may be present. This general model of the flanks also explains the main CO2 patterns: concentration of CO2 at the surface is high on the porous north flank and lower on the other flanks where impermeable layers can block the upward CO2 flux. The active upper part of the island is underlain by a well-defined hydrothermal system bounded by short-wavelength negative SP anomalies and high peaks of CO2. These boundaries coincide with faults limiting ancient collapses of calderas, craters and flank landslides. The hydrothermal system is not homogeneous but composed of three main subsystems and of a fourth minor one and is not centered on the active craters. The latter are located near its border. This divergence between the location of the active craters and the extent of the hydrothermal system suggests that the internal heat sources may not be limited to sources below the active craters. If the heat source strictly corresponds to intrusions at depth around the active conduits, the geometry of the hydrothermal subsystems must be strongly controlled by heterogeneities within the edifice such as craters, caldera walls or gliding planes of flank collapse, as suggested by the correspondence between SP^CO2 anomalies and structural limits. The inner zone of the hydrothermal subsystems is characterized by positive SP anomalies, indicating upward movements of fluids, and by very low values of CO2 emanation. This pattern suggests that the hydrothermal zone becomes self-sealed at depth, thus creating a barrier to the CO2 flux. In this hypothesis, the observed hydrothermal system is a shallow one and it involves mostly convection of infiltrated meteoric water above the sealed zone. Finally, on the base of CO2 degassing measurements, we present evidence for the presence of two regional faults, oriented N41‡ and N64‡, and decoupled from the volcanic structures.
    Description: Published
    Description: 1^18
    Description: partially_open
    Keywords: Stromboli ; hydrothermal system ; self-potential ; soil gas ; carbon dioxide ; Aeolian islands ; 03. Hydrosphere::03.02. Hydrology::03.02.02. Hydrological processes: interaction, transport, dynamics ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data ; 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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    Isotopic, chemical and dissolved gas constraints on spring water from Popocatepetl volcano (Mexico): evidence of gas–water interaction between magmatic component and shallow fluids (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Geochemical research was carried out on cold and hot springs at Popocatepetl (Popo) volcano (Mexico) in 1999 to identify a possible relationship with magmatic activity. The chemical and isotopic composition of the fluids is compatible with strong gas–water interaction between deep and shallow fluids. In fact, the isotopic composition of He and dissolved carbon species is consistent with a magmatic origin. The presence of a geothermal system having a temperature of 80–1008 C was estimated on the basis of liquid geothermometers. A large amount of dissolved CO2 in the springs was also detected and associated with high CO2 degassing.
    Description: Published
    Description: 91– 108
    Description: partially_open
    Keywords: Popocatepetl volcano ; helium isotope composition ; carbon isotope composition ; dissolved gases ; gas–water interaction ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 28
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    Genesis of fumarolic emissions as inferred by isotope mass balances: CO2 and water at Vulcano Island, Italy (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: We have developed a quantitative model of CO2 and H2O isotopic mixing between magmatic and hydrothermal gases for the fumarolic emissions of the La Fossa crater (Vulcano Island, Italy). On the basis of isotope balance equations, the model takes into account the isotope equilibrium between H2O and CO2 and extends the recent model of chemical and energy two-end-member mixing by Nuccio et al. (1999). As a result,the H2O and CO2 content and the dD, d18O, and d13C isotope compositions for both magmatic and hydrothermal end-members have been assessed. Low contributions of meteoric steam, added at a shallow depth, have been also recognized and quantified in the fumaroles throughout the period from 1988 to 1998. Nonequilibrium oxygen isotope exchange also seems to be occurring between ascending gases and wall rocks along some fumarolic conduits. The d13CCO2 of the magmatic gases varies around -3 to 1‰ vs. Peedee belemnite (PDB), following a perfect synchronism with the variations of the CO2 concentration in the magmatic gases. This suggests a process of isotope fractionation because of vapor exsolution caused by magma depressurization. The hydrogen isotopes in the magmatic gases (-1 to -35‰ vs. standard mean ocean water [SMOW]), as well as the above d13CCO2 value, are coherent with a convergent tectonic setting of magma generation, where the local mantle is widely contaminated by fluids released from the subducted slab. Magma contamination in the crust probably amplifies this effect. The computed isotope composition of carbon and hydrogen in the hydrothermal vapors has been used to calculate the dD and d13C of the entire hydrothermal system, including mixed H2O-CO2 vapor, liquid water, and dissolved carbon. We have computed values of about 10‰ vs. SMOW for water and -2 to -6.5‰ vs. PDB for CO2. On these grounds, we think that Mediterranean marine water (dDH2O 10‰) feeds the hydrothermal system. It infiltrates at depth throughout the local rocks, reaching oxygen isotope equilibrium at high temperatures. Interaction processes between magmatic gases and the evolving seawater also seem to occur, causing the dissolution of isotopically fractionated aqueous CO2 and providing the source for hydrothermal carbon. These results have important implications concerning fluid circulation beneath Vulcano and address the more convenient routine of geochemical surveillance.
    Description: Published
    Description: 759–772
    Description: partially_open
    Keywords: isotope geochemistry ; volcanic gases ; mixing modeling ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 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::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 29
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    Influence of volcanic activity on spring water chemistry at Popocatepetl Volcano, Mexico (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The results of the 7 years (1994-2000) of monthly monitoring of spring water before and during eruptions show response to volcanic activity. Low salinity and temperature characterize most of the springs, which are located on the flanks of Popocatepetl Volcano. The pH ranges from 5.8 to 7.8 and temperature from 3 to 36 jC. Oxygen and hydrogen isotopic data show that the water is of meteoric origin, but SO4 2 , Cl , F , HCO3 , B, and SO4 2- /Cl- variations precede main eruptive activity, which is considered linked to influx of magmatic gases and acid fluids that react with sublimates and host rock and mix with the large water system. Na +, Ca2 + , SiO2 and Mg2 + concentrations in the water also increased before eruptive activity. The computed partial pressure of CO2 in equilibrium with spring waters shows values higher than air-saturated water (ASW), with the highest values up to 0.73 bar of pCO2. Boron is detected in the water only preceding the larger eruptions. When present, boron concentration is normally under health standard limits, but in two cases the concentration was slightly above. Other components are within health standard limits, except for F- in one spring.
    Description: Published
    Description: 207– 229
    Description: partially_open
    Keywords: Volcano monitoring ; Spring water chemistry ; Popocatepetl ; Mexico ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
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