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  • 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry  (11)
  • Elsevier  (9)
  • Springer-Verlag  (2)
  • Essen : Verl. Glückauf
  • Krefeld : Geologischer Dienst Nordhein-Westfalen
  • Oxford University Press
  • 2005-2009  (11)
  • 2009  (7)
  • 2006  (4)
Collection
Years
  • 2005-2009  (11)
Year
  • 1
    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
    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)
    Type: article
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  • 3
    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
    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
    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
    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
    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
    Publication Date: 2017-04-04
    Description: Measurements of CO2 flux from the ground were periodically carried out on the island of Vulcano (Aeolian Islands, Italy) between 1984 and 1994. Three high-flux areas were identified at the foot of the volcanic cone (La Fossa), either inside or very close to the main village. Effect of the choice of the sampling grid was evaluated. A different sampling grid resulted in similar distribution patterns, but with different CO2 fluxes. Therefore, the absolute estimate of the total flux from the investigated area includes a large degree of uncertainty, but repeated measurements with permanent sampling sites are accurate and can detect small changes. No correlation of the flux with atmospheric parameters was found at sites with high fluxes. Some periods characterized by high CO2 fluxes were observed, and a close correlation was found between the gas emissions from the ground and other geochemical and geophysical parameters such as temperature, chemical composition, steam, and SO2 flux from fumaroles, seismic energy release, and ground deformations. The results show that major temporal variations of diffuse CO2 flux are related to variations in volcanic activity.
    Description: Gruppo Nazionale per la Vulcanologia CNR Italy.
    Description: Published
    Description: 219–228
    Description: partially_open
    Keywords: CO2 ; Flux measurements ; Gas emissions ; Soil gas ; Volcanic activity ; Vulcano ; 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
    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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  • 10
    Publication Date: 2017-04-04
    Description: Significant changes in the helium and carbon isotopic composition of shallow thermal waters vs. gas and a crater fumarolic gas have been recorded at Stromboli prior and during the 2002–2003 eruption. The 3He/4He ratios corrected for air contamination (Rc/Ra), and δ13C of fumarolic gases gradually increased from May to November 2002 before the eruption onset. These variations imply early degassing of a gas-rich magma at depth that likely fed both the intense Strombolian activity and small lava overflows recorded during that period. The lava effusion of late December 2002 was shortly preceded by a marked Rc/Ra decrease both in water and fumarolic gases. Comparison of He/CO2 and CH4/CO2 ratios in dissolved gas and with δ13CCO2 values rules out the Rc/Ra decrease due to an increasing input of radiogenic 4He. The Rc/Ra decrease is attributed to the He isotope fractionation during rapid magma ascent and degassing. A new uprising of 3He-rich magma probably occurred in January to February 2003, when Rc/Ra ratios displayed the highest values in dissolved gases ever measured before (4.56 Rc/Ra). The increase in He/CO2 and CH4/CO2 ratios and decrease in δ13C of dissolved CO2 was recorded after the 5 April 2003 explosive paroxysm, likely caused by enhanced gas-water interaction inducing CO2 dissolution. No anomalous Rc/Ra values were recorded in the same period, when usual Strombolian activity gradually resumed.
    Description: Published
    Description: 118–134
    Description: partially_open
    Keywords: Stromboli ; Eruption ; Geochemistry ; Helium ; Isotopes ; Magma ascent ; Dissolved gases ; 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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  • 11
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    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.
    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
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