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  • 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases  (14)
  • 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous
  • modelling
  • Elsevier Science Limited  (18)
  • Blackwell Publishing Ltd  (6)
  • American Chemical Society
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Keywords
  • 1
    Publication Date: 2021-03-01
    Description: Between 1994 and 1995, gas samples from fumaroles and thermal waters were collected on Ischia Island. The chemical composition of the shallow and deep natural hydrothermal fluids discharged is related to the main hydrological and lithological characteristics of the rock formations present in the reservoir. A biphase reservoir (liquid 1 gas) is identified, where the dominant liquid has a temperature of about 2808C. On the basis of d 13CTDC values it was possible to hypothesize a deep source characterised by carbon isotopic values varying from 0 to 23d‰. These values are noticeably more positive with respect to those attributed to magmatic CO2 d13CCO2 ranging from 25 to 28d ‰), thus suggesting a magmatic source modified by crustal contamination. This hypothesis is supported by the carbon isotopic composition of CO2 in sampled gases, which varied from 0 to 25d‰. The inferred isotopic value of carbon of magmatic CO2 would then be about 22d‰. The observed differences in C isotopic composition between fumarolic and magmatic gases would be caused by kinetic and/or equilibrium fractionation processes. These processes would cause a fractionation of d 13C of deep CO2 towards more negative values (down to 25‰). Actually, CO2 removal or addition processes caused by the interaction between deep gases and shallow hydrothermal waters are likely to be responsible for the different chemical and isotopic compositions of gaseous emissions. For these reasons, and on the basis of the homogeneity of geothermometric values, the existence of a single, large reservoir that feeds all of the fluids discharged at Ischia Island can be hypothesised. Based on acquired data, a new geochemical model of the geothermal system of Ischia Island is proposed.
    Description: Published
    Description: 151-178
    Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio
    Description: JCR Journal
    Keywords: gas thermometers; water geothermometer; dissolved gases; geothermal system; Ischia Island ; 03. Hydrosphere::03.02. Hydrology::03.02.02. Hydrological processes: interaction, transport, dynamics ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2021-06-15
    Description: We investigated the geochemical features of the fluids circulating over the Amik Basin (SE Turkey–Syria border), which is crossed by the Northern extension of theDSF (Dead Sea Fault) and represents the boundary area of three tectonic plates (Anatolian, Arabian and African plates). We collected 34 water samples (thermal and cold from natural springs and boreholes) as well as 8 gas samples (bubbling and gas seepage) besides the gases dissolved in the sampled waters. The results show that the dissolved gas phase is a mixture of shallow (atmospheric) and deep components either of mantle and crustal origin. Coherently the sampled waters are variable mixtures of shallow and deep ground waters, the latter being characterised by higher salinity and longer residence times. The deep groundwaters (fromboreholes deeper than 1000 m)have a CH4-dominated dissolved gas phase related to the presence of hydrocarbon reservoirs. The very unique tectonic setting of the area includes the presence of an ophiolitic block outcropping in the westernmost area on the African Plate, as well as basalts located to the North and East on the Arabic Plate. The diffuse presence of CO2-enriched gases, although diluted by the huge groundwater circulation, testifies a regional degassing activity. Fluids circulating over the ophiolitic block are marked by H2-dominated gases with abiogenic methane and high-pH waters. The measured 3He/4He isotopic ratios display contributions from both crustal and mantle-derived sources over both sides of the DSF. Although the serpentinization process is generally independent from mantle-type contribution, the recorded helium isotopic ratios highlight variable contents of mantle-derived fluids. Due to the absence of recent volcanism over the western side of the basin (African Plate), we argue that CO2-rich volatiles carrying mantle-type helium and enriched in heavy carbon, are degassed by deep-rooted regional faults rather than from volcanic sources.
    Description: Published
    Description: 23–39
    Description: 2T. Tettonica attiva
    Description: JCR Journal
    Description: restricted
    Keywords: Dead Sea Fault ; Hydrogeochemistry ; Gas geochemistry ; He isotopes ; C isotopes ; Ophiolites ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.04. Chemical and biological::03.04.02. Carbon cycling ; 03. Hydrosphere::03.04. Chemical and biological::03.04.03. Chemistry of waters ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 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
    Publication Date: 2017-04-04
    Description: The tectonic deformation of the Lipari-Vulcano complex, one of the most important active volcanic areas of Mediterranean region, is studied here through the analysis of ten years (1996-2006) of GPS data from both 3 permanent and 13 non-permanent stations. This area can be considered crucial for the understanding of the Eurasia-Africa plates interaction in the Mediterranean area, and, in general, this work emphasize a methodological approach, already applied in other areas worldwide (e.g. Shen et al., 1996, El-Fiki and Kato, 1999) where geodetic data and strain parameters maps of critical areas can help to improve our understanding of their geodynamical aspects. In this framework, this study is aimed at providing a kinematic deformation model on the basis of the dense geodetically estimated velocities of the Lipari-Vulcano complex. In particular, the observed deformation pattern can be described by a mix between 1) the main N-S regional compression and 2) a NNE-SSW compression with a small right-lateral strike slip component acting along a tectonic structure N°40W trending located between the two islands. This pattern was inspected through a simplified synthetic model.
    Description: This research has benefited from funding provided by the Italian Presidenza del Consiglio dei Ministri – Dipartimento della Protezione Civile (DPC).
    Description: Published
    Description: 370–377
    Description: 1.9. TTC - Rete GPS nazionale
    Description: JCR Journal
    Description: reserved
    Keywords: GPS ; Aeolian Islands ; strain ; modelling ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 4
    Publication Date: 2017-04-04
    Description: The paper describes a case of a natural emission of methane from soil in an urban development area, generating a significant risk for the local population and buildings, due to gas explosiveness and asphyxiation potential. The site is located on the south-western margin of the East-European Platform in eastern Romania, in a hydrocarbon-prone area crossed by the Pericarpathian lineament and regional faults. Molecular composition of gas and stable isotopic analyses of methane (CH4〉90%, δ to the power of 13 C1: -49.4‰, δD1: -173.4‰) indicate a dominant thermogenic origin, with significant amounts of C2-C5 alkanes (~5%), likely migrating through faults from a deep reservoir. Possible candidates are the Saucesti and Secuieni gas fields, located in the same petroleum system. Two surface geochemical surveys, based on closed-chamber flux measurements, were performed to assess the degassing intensity and the extent of the affected area. Methane fluxes from soil reach orders of 10 to the power of 4 mg m to the power of -2 day to the power of -1. Gas seepage mainly occurs in one zone 30 000 m2 wide, and it is likely controlled by channeling along a fault and gas accumulation in permeable sediments and shallow subsoil. The estimated total CH4 emission is about 40 t year to the power of -1 CH4, of which 8–9 t year to the power of -1 are naturally released from soil and 30–35 t year to the power of -1 are emitted from shallow boreholes. These wells have likely channeled the gas accumulated in shallow alluvial sediment but gas flux from soil is still high and mitigation measures are needed to reduce the risk for humans and buildings.
    Description: Published
    Description: 311-320
    Description: 3.8. Geofisica per l'ambiente
    Description: JCR Journal
    Description: reserved
    Keywords: gas hazard ; methane seepage ; soil degassing ; thermogenic gas ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 5
    Publication Date: 2017-04-04
    Description: The Chimaera gas seep, near Antalya (SW Turkey), has been continuously active for thousands of years and it is known to be the source of the first Olympic fire in the Hellenistic period. New and thorough molecular and isotopic analyses including methane (approximately 87% v/v; δ to the power of 13 C1 from -7.9‰ to -12.3‰; δ to the power of 13 D1 from -119‰ to -124‰), light alkanes (C2 + C3 + C4 + C5 = 0.5%; C6+: 0.07%; δ to the power of 13 C2 from -24.2‰ to -26.5‰; δ to the power of 13 C3 from -25.5‰ to -27‰), hydrogen (7.5–11%), carbon dioxide (0.01–0.07%; δ to the power of 13 CCO2: -15‰), helium (approximately 80 ppmv; R/Ra: 0.41) and nitrogen (2–4.9%; δ to the power of 15 N from -2‰ to -2.8‰) converge to indicate that the seep releases a mixture of organic thermogenic gas, related to mature type III kerogen occurring in Palaeozoic and Mesozoic organic-rich sedimentary rocks, and abiogenic gas produced by low-temperature serpentinization in the Tekirova ophiolitic unit. Methane is not related to mantle or magma degassing. The abiogenic fraction accounts for about half of the total gas released, which is estimated to be well beyond 50 ton year to the power of -1. Ophiolites and limestones are in contact along a tectonic dislocation leading to gas mixing and migration to the Earth’s surface. Chimaera represents the biggest emission of abiogenic methane on land discovered so far. Deep and pressurized gas accumulations are necessary to sustain the Chimaera gas flow for thousands of years and are likely to have been charged by an active inorganic source.
    Description: Published
    Description: 263-273
    Description: 3.8. Geofisica per l'ambiente
    Description: JCR Journal
    Description: reserved
    Keywords: abiogenic methane ; isotopic composition ; ophiolites ; seep ; serpentinization ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
    Publication Date: 2017-04-04
    Description: In eastern Elba Island (Tuscany, Italy), a shallow crustal level felsic, tourmaline-bearing, dyke-sill swarm of Late Miocene age is associated with abundant tourmaline-quartz hydrothermal veins and metasomatic masses. Development of these veins and masses in the host rocks demonstrates multiple hydro-fracturing by magmatic, boron-rich saline fluid. Tourmalines in felsic dykes are schorl, whereas in veins and metasomatic masses, tourmaline composition ranges from schorl-dravite through dravite to uvite. This compositional shift is evidence for an increasing contribution to the magmatic boron-rich fluids by a Mg-Ca-Ti-rich external component represented by biotite-rich and amphibolite host rocks. This system can be envisaged as an exposed proxy of the high temperature hydrothermal system presently active in the deepest part of the Larderello-Travale geothermal field (Tuscany).
    Description: Published
    Description: 318-326
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: JCR Journal
    Description: reserved
    Keywords: Hydro-fractures ; geothermal systems ; Magmatism ; southern Tuscany ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
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    Elsevier Science Limited
    In:  Supplementary data associated with this article can be found in the online version, at http://dx.doi.org/10.1016/j.jvolgeores.2012.08. 013.
    Publication Date: 2017-04-04
    Description: A pilot GIS-based system has been implemented for the assessment and analysis of hazard related to active faults affecting the eastern and southern flanks of Mt. Etna. The system structure was developed in ArcGis® environment and consists of different thematic datasets that include spatially-referenced arc-features and associated database. Arc-type features, georeferenced into WGS84 Ellipsoid UTM zone 33 Projection, represent the five main fault systems that develop in the analysed region. The backbone of the GIS-based system is constituted by the large amount of information which was collected from the literature and then stored and properly geocoded in a digital database. This consists of thirty five alpha-numeric fields which include all fault parameters available from literature such us location, kinematics, landform, slip rate, etc. Although the system has been implemented according to the most common procedures used by GIS developer, the architecture and content of the database represent a pilot backbone for digital storing of fault parameters, providing a powerful tool in modelling hazard related to the active tectonics of Mt. Etna. The database collects, organises and shares all scientific currently available information about the active faults of the volcano. Furthermore, thanks to the strong effort spent on defining the fields of the database, the structure proposed in this paper is open to the collection of further data coming from future improvements in the knowledge of the fault systems. By layering additional user-specific geographic information and managing the proposed database (topological querying) a great diversity of hazard and vulnerability maps can be produced by the user. This is a proposal of a backbone for a comprehensive geographical database of fault systems, universally applicable to other sites.
    Description: Published
    Description: 170-186
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: 5.5. TTC - Sistema Informativo Territoriale
    Description: JCR Journal
    Description: reserved
    Keywords: GIS-based system ; Hazard assessment ; Volcano-tectonics ; Flank dynamics ; Georeferenced arc-features ; Active fault database ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 05. General::05.08. Risk::05.08.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 8
    Publication Date: 2017-04-04
    Description: Several volcanoes worldwide have shown changes in their stress state as a consequence of the deformation produced by the pressurization of a magmatic body. This study investigates seismic swarms occurring on the western flank of Mt. Etna in January 1997 - January 1998. Integrating seismic observations and geodetic data, we constrained the seismogenic fault system, and on the basis of stress tensor inversion and SHMAX analyses, we infer an inflating pressure source located at 5.5 km b.s.l. beneath the west portion of summit area. Evaluation of Coulomb failure stress (CFS) related to the proposed model, showed how a large part of the seismogenic fault underwent a significant CFS increase (500 kPa). We infer the presence of a sub-vertical faulted region, potentially weak, N50°E oriented beneath the western sector of Mt. Etna. This structure could be brought closer to failure thereby generating seismic swarms as the effect of elastic stress transfer induced by movement and/or overpressure of magmatic masses within the upper crust under the volcano.
    Description: This research was funded by the INGV–DPC 2007–2009 Agreement (Project V4_Flank).
    Description: Published
    Description: 339-348
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: restricted
    Keywords: Etna ; modelling ; Seismicity ; GPS monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
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    Elsevier Science Limited
    Publication Date: 2020-02-24
    Description: Different tectonic units cover the Antarctic territory: platform, orogens and depression structures. This structural variability is reflected both in thickness and physical properties of the crust.We present a new Moho map for the Antarctica, derived from geophysical data selected from the literature. Themodel covers thewhole Antarctic region, from the South Pole out to the continental margin, including the Antarctic Peninsula. TheMoho depth is represented with a resolution of 1°×1° on a Cartesian grid obtained by an equidistant azimuthal geographical projection. A large volume of new data has been analyzed: mostly seismic experiments, as well as receiver functions and geological studies. In general,we can identify three large domainswithin the Antarctic continental crust. The oldest Archean and Proterozoic crust of East Antarctica has a thickness of 36–56 km (with an average of about 41 km). The continental crust of the Transantarctic Mountains, the Antarctic Peninsula and Wilkes Basin has a thickness of 30–40 km (with an average Moho of about 30 km). The youngest rifted continental crust of the West Antarctic Rift System has a thickness of 16–28 km (with an average Moho of about 26 km). The mean Moho depth of the whole model is 33.8 km. The new Moho model exhibits some remarkable disagreements at places with respect to global model CRUST 2.0. Difference between these two models may range up to −10/+24 km. The new model is available for download in digital format. We plan to update the model in the near future by including new data, particularly in the most poorly covered regions.
    Description: Published
    Description: 299-313
    Description: 1T. Geodinamica e interno della Terra
    Description: JCR Journal
    Description: restricted
    Keywords: Crustal structure ; Moho ; Antarctica ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
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    Blackwell Publishing Ltd
    Publication Date: 2017-04-04
    Description: We present a new crustal model for the European plate, derived from collection and critical integration of information selected from the literature. The model covers the whole European plate from North Africa to the North Pole (20N - 90N) and from the Mid-Atlantic Ridge to the Urals (40W - 70E). The chosen parameterization represents the crust in three layers (sediments, upper crust and lower crust), and describes the 3D geometry of the interfaces and seismologically-relevant parameters — isotropic P- and S-wave velocity, plus density — with a resolution of 0.5 × 0.5 degrees on a geographical latitude-longitude grid. We selected global and local models, derived from geological assumptions, active seismic experiments, surface-wave studies, noise correlation, receiver functions. Model EPcrust presents significant advantages with respect to previous models: it covers the whole European plate; it is a complete and internally-consistent model (with all the parameters provided, also for the sedimentary layer); it is reproducible; it is easy to update in the future by adding new contributions; and it is available in a convenient digital format. EPcrust could be used to account for crustal structure in seismic wave propagation modeling at continental scale or to compute linearized crustal corrections in continental-scale seismic tomography, gravity studies, dynamic topography and other applications that require a reliable crustal structure. Because of its resolution, our model is not suited for local-scale studies, such as the computation of earthquake scenarios, where more detailed knowledge of the structure is required. We plan to update the model as new data will become available, and possibly improve its resolution for selected areas in the future.
    Description: Published
    Description: 352-364
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: Europe ; crust ; crustal properties ; Moho ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.01. Earth Interior::04.01.01. Composition and state
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 11
    Publication Date: 2017-04-04
    Description: Volcanic edifices are often unable to support their own load, triggering the instability of their flanks. Many analogue models have been aimed, especially in the last decade, at understanding the processes leading to volcano flank instability; general behaviors were defined and the experimental results were compared to nature. However, available data at well-studied unstable volcanoes may allow a deeper understanding of the specific processes leading to instability, providing insights also at the local scale. Etna (Italy) constitutes a suitable example for such a possibility, because of its well-monitored flank instability, for which different triggering factors have been proposed in the last two decades. Among these factors, recent InSAR data highlight the role played by magmatic intrusions and a weak basement, under a differential unbuttressing at the volcano base. This study considers original and recently published experimental data to test these factors possibly responsible for flank instability, with the final aim to better understand and summarize the conditions leading to flank instability at Etna. In particular, we simulate the following processes: a) the longterm activity of a lithospheric boundary, as the Malta Escarpment, separating the Ionian oceanic lithosphere from the continental Sicilian lithosphere, below the most unstable east flank of the volcano; b) spreading due to a weak basement, with different boundary conditions; c) the pressurization of a magmatic reservoir, as that active during the 1994–2001 inflation period; d) dike emplacement, as observed during the major 2001 and 2002–2003 eruptions. The experimental results suggest that: 1) the long-term activity of a lithospheric tectonic boundary may create a topographic slope which provides a differential buttressing at the volcano base, a preparing factor to drive longer-term (〉105 years) instability on the east flank of the volcano; 2) volcano spreading (b104 years) has limited effect on flank instability at Etna; 3) magmatic intrusions (b101 years), both in the form of Mogi-like sources or dikes, provide the most important conditions to trigger flank instability on the shorter-term.
    Description: Thisworkwas partially funded by INGV and the Italian DPC (DPC-INGV project V4 “Flank”).
    Description: Published
    Description: 98-111
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: volcano instability ; analogue modeling ; Etna ; unbuttressing ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 12
    Publication Date: 2017-04-04
    Description: A geochemical survey, in shallow aquifers and soils, has been carried out to evaluate the feasibility of natural gas (CH4) storage in a deep saline aquifer at Rivara (MO), Northern Italy. This paper discusses the areal distribution of CO2 and CH4 fluxes and CO2, CH4, Rn, He, H2 concentrations both in soils and shallow aquifers above the proposed storage reservoir. The distribution of pathfinder elements such as 222Rn, He and H2 has been studied in order to identify potential faults and/or fractures related to preferential migration pathways and the possible interactions between the reservoir and surface. A geochemical and isotopic characterization of the ground waters circulating in the first 200 m has allowed to investigation of (i) the origin of the circulating fluids, (ii) the gas–water–rock interaction processes, (iii) the amount of dissolved gases and/or their saturation status. In the first 200 m, the presence of CH4-rich reducing waters are probably related to organic matter (peat) bearing strata which generate shallowderived CH4, as elsewhere in the Po Plain. On the basis of isotopic analysis, no hints of thermogenic CH4 gas leakage from a deeper reservoir have been shown. The d13C(CO2) both in ground waters and free gases suggests a prevalent shallow origin of CO2 (i.e. organic and/or soil-derived). The acquisition of preinjection data is strategic for the natural gas storage development project and as a baseline for future monitoring during the gas injection/withdrawing period. Such a geochemical approach is considered as a methodological reference model for future CO2/CH4 storage projects.
    Description: Published
    Description: 3-22
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: restricted
    Keywords: natural gas storage ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 13
    Publication Date: 2017-04-04
    Description: Shallow submarine gas vents in Levante Bay, Vulcano Island (Italy), emit around 3.6t CO2 per day providing a natural laboratory for the study of biogeochemical processes related to seabed CO2 leaks and ocean acidification. The main physico-chemical parameters (T, pH and Eh) were measured at more than 70 stations with 40 seawater samples were collected for chemical analyses. The main gas vent area had high concentrations of dissolved hydrothermal gases, low pH and negative redox values all of which returned to normal seawater values at distances of about 400 m from the main vents. Much of the bay around the vents is corrosive to calcium carbonate; the north shore has a gradient in seawater carbonate chemistry that is well suited to studies of the effects of long-term increases in CO2 levels. This shoreline lacks toxic compounds (such as H2S) and has a gradient in carbonate saturation states.
    Description: Published
    Description: 485–494
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: restricted
    Keywords: ocean acidification ; carbon capture and storage ; marine geochemistry ; carbonate saturation state ; volcanic vents ; carbon dioxide ; 03. Hydrosphere::03.04. Chemical and biological::03.04.01. Biogeochemical cycles ; 03. Hydrosphere::03.04. Chemical and biological::03.04.02. Carbon cycling ; 03. Hydrosphere::03.04. Chemical and biological::03.04.03. Chemistry of waters ; 03. Hydrosphere::03.04. Chemical and biological::03.04.04. Ecosystems ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 14
    Publication Date: 2017-04-03
    Description: Subduction zones are the place in the world where fluids are transported from the foredeep to the mantle and back-to-the-surface in the back-arc. The subduction of an oceanic plate implies the transportation of the oceanic crust to depth and its methamorphization. Oceanic sediments release water in the (relatively) shallower part of the subduction zone, while dehydration of the subducted basaltic crust allows fluid circulation at larger depths. While the water budget in oceanic subduction has been deeply investigated, less attention has been given to the fluids implied in the subduction of a continental margin (i.e. in continental subduction). In this study, we use teleseismic receiver function (RF) analysis to image the process of water migration at depth, from the subducting plate to the mantle wedge, under the Northern Apennines (NAP, Italy). Harmonic decomposition of the RF data-set is used to constrain both isotropic and anisotropic structures. Isotropic structures highlight the subduction of the Adriatic lower crust under the NAP orogens, from 35–40 km to 65 km depth, as a dipping low S-velocity layer. Anisotropic structures indicate the presence of a broad anisotropic zone (anisotropy as high as 7%). This zone develops in the subducted Adriatic lower crust and mantle wedge, between 45 and 65 km depth, directly beneath the orogens and the more recent back-arc extensional basin. The anisotropy is related to the metamorphism of the Adriatic lower crust (gabbro to blueschists) and its consequent eclogitization (blueschists to eclogite). The second metamorphic phase releases water directly in the mantle wedge, hydrating the back-arc upper mantle. The fluid migration process imaged in this study below the northern Apennines could be a proxy for understanding other regions of ongoing continental subduction.
    Description: Published
    Description: 267–278
    Description: JCR Journal
    Description: restricted
    Keywords: fluid migration; seismic anisotropy; Northern Apennines; receiver function ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 15
    Publication Date: 2017-04-04
    Description: We analyzed crater SO2 fluxes from Mt Etna, together with soil CO2 effluxes from the volcano's flanks, in the period from 2001 to 2005. Between the 2001 and 2002–2003 eruptions, persistently low values of both parameters suggest that no new gas-rich magma was accumulating at shallow depth (b5 km) within Etna's central conduit, whereas very high SO2 sin-eruptive fluxes during the two eruptions indicated sudden decompression of an un-degassed magma rising along newly-formed eccentric conduits. In November 2003, soil CO2 data indicate migration of gas-rich magma from deep (〉10 km) to shallow (b5 km) portions of the feeding conduits, preceded by an increase in crater SO2 fluxes. A similar behavior was observed also during and after the following 2004–2005 eruption. This degassing style matches a period of increased structural instability of the volcanic edifice caused by acceleration of spreading that affected both its eastern and southern flanks. Spreading could have triggered progressively deeper depressurization in the central conduit, inducing release of the more soluble gas (SO2) first, and then of CO2, contrary to what was observed before the 2001 eruption. This suggests that the edifice has depressurized, promoting ascent of fresh-magma and increasing permeability favouring release of CO2 flux. By integrating geochemical and structural data, previous degassing models developed at Mt. Etna have been updated to advance the understanding of eruptive events that occurred in recent years.
    Description: This work was funded by grants from the Istituto Nazionale di Geofisica e Vulcanologia (INGV) and from the Dipartimento per la Protezione Civile (Italy).
    Description: Published
    Description: 90-97
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 3.6. Fisica del vulcanismo
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: reserved
    Keywords: Geochemical modeling ; volcano monitoring ; volcanic gases ; Tectonics and magmatism ; flank collapse ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 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 ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 05. General::05.08. Risk::05.08.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 16
    Publication Date: 2017-04-04
    Description: Soil–gas measurements of different gas species were performed in two distinct areas of the Corinth Gulf Rift (Greece): the Aigion-Neos Erineos-Lambiri (ANEL) fault zone and the Rion-Patras fault zone. Both zones lie in one of the most seismically active areas of the Euro-Mediterranean region, where a fast-opening continental rift is located. In particular, the geochemical investigations were focused on fault segments and fracture systems previously inferred by geomorphological, lithological and structural studies. In this work the applicability of soil–gas geochemistry surveys for the exploration of buried/hidden faults was tested by using various statistical methods. Moreover, a comprehensive geostatistical treatment of the collected data provided new insights into the control exerted by active structures on deep-seated gas migration towards the surface. In both investigated areas, the highest 222Rn and CO2 concentration peaks correspond with zones where the interaction among fracture and fault segments was inferred by structural and morphological methods. This indicates a clear correlation between the shape and orientation of the anomalies and the different attitude and kinematic behavior of the faults recognized in the two areas. Furthermore, obtained results show that gases migrate preferentially through zones of brittle deformation by advective processes, as suggested by the relatively high rate of migration needed to obtain anomalies of short-lived 222Rn in the soil pores
    Description: Published
    Description: 86-100
    Description: 5A. Energia e georisorse
    Description: JCR Journal
    Description: restricted
    Keywords: gas geochemistry ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 17
    Publication Date: 2019-01-09
    Description: A comprehensive hydrogeochemical study of the cold and thermal groundwaters of the presently quiescent volcanic system at Methana was undertaken that involved collecting 71 natural water samples. Methana is a peninsula in Peloponnesus, Greece whose arid climate and hydrological situation is similar to that of the nearby small islands of the Aegean Sea. Similarly, the chemical and isotopic compositions of its water are dominated by the mixing of seawaterwith meteoric water both through direct intrusion and meteoric recharge. However, the simple mixing trends at Methana are modified by water–rock interaction processes, enhanced by the dissolution of endogenous CO2, which lead to strong enrichments in alkalinity, Ca, Ba, Fe and Mn. The thermal waters show very high salinity that is sometimes close to that of seawater [total dissolved solids (TDS)=8.5–40 g/l]. Although the cold groundwaters sometimes also show elevated TDS values (up to 6.3 g/l), their overall quality is acceptable due to the trace metal and nitrate contents mostly being below acceptable limits. While the saltiest groundwaters are not acceptable for human consumption, they are used for irrigation without exerting toxic effects on plants, which is probably due to the high permeability of the soils not supporting salt accumulation and salinity-resistant crops being cultivated.
    Description: Published
    Description: 110-119
    Description: 4V. Vulcani e ambiente
    Description: JCR Journal
    Description: restricted
    Keywords: Hydrogeochemistry ; volcanic aquifers ; Salinization ; stable isotopes ; Trace elements ; 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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 18
    Publication Date: 2020-02-24
    Description: The occurrence and origin of methane (CH4) generated by serpentinization of ultramafic rocks is of current timely interest in planetary geology, astrobiology and energy resource exploration, as it may contribute, in particular, to decipher the source of methane on Mars, the origin of life and the potential of abiotic hydrocarbon synthesis. Methane of dominant abiotic origin in serpentinized peridotites on continents (ophiolites or igneous intrusions) has been documented so far, with complete carbon and hydrogen isotope composition, in six countries, in the Philippines, Turkey, Oman, New Zealand, Japan and Italy. We report the discovery of two new sites in Greece, at Archani and Ekkara, located in the Othrys ophiolite massif. Portable sensors based on Fourier Transform InfraRed spectrometry (FTIR) and Tunable Diode Laser Absorption Spectroscopy (TDLAS) allowed to realize that out of 21 ophiolitic springs, methane is released only by four hyperalkaline (pH from 10.7 to 11.3) and calcium hydroxide (Ca–OH) type waters; all other 17 springs with pH b 8.7 and magnesium-rich waters in the Pindos, Vourinos and Veria ophiolites, do not show methane. This correlation between gas occurrence and water type seems to occur worldwide; accordingly, CH4 production appears to be intimately related to the depth and residence time of the circulating meteoric waters. Methane is emitted into the atmosphere also from the soil surrounding the hyperalkaline springs, with fluxes of the same order of magnitude (~102–103 mg m−2 day−1) of seepage typically observed over conventional petroleum systems. Othrys CH4 has an isotopic composition (δ13C from −27‰ to −37.3‰ VPDB, δ2H from −250‰ to −311‰ VSMOW) similar to that reported in ultramafic rocks in New Zealand and Japan, and in Precambrian crystalline shields, which were considered dominantly abiotic and probably derived from Fischer–Tropsch Type reactions. The paucity of CO2, which is the norm in hyperalkaline waters, and of other hydrocarbons prevents from evaluating possible mixing of gas of different sources, including microbial methanogenesis. Also the H2 content is trivial, notwithstanding it being a typical product of serpentinization; this could be due to complete H2 consumption by CO2 reduction in a limited or decreased H2 production system due, for example, to a late stage of increased silica activity, as suggested by preliminary petrographic observations. The low geothermal gradient of the area and the present-day serpentinization imply that,whatever the CH4 production mechanism, it took place at temperatures below those traditionally considered for the origin of abiotic methane in hydrothermal systems.
    Description: Published
    Description: 161-174
    Description: 7A. Geofisica di esplorazione
    Description: JCR Journal
    Description: restricted
    Keywords: Abiotic methane, serpentinization, ophiolite ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 19
    Publication Date: 2017-04-04
    Description: Using a multidisciplinary dataset based on gravimetric, seismic, geodetic and geological observations,we provide an improved picture of the shallow structure and dynamics of the southern edge of the Tyrrhenian subduction zone.With a local earthquake tomographywe clearly identify twomain crustal domains in the upper 15 kmcharacterized by different P-wave velocity values: a high-velocity domain comprising southeasternmost Tyrrhenian Sea, NE Sicily and Messina Straits, and a low-velocity domain comprising Mt. Etna and eastern Sicily. The transition between the two domains shows a good spatial correspondence with a wider set of faults including the Taormina Fault System (TFS) and the Aeolian–Tindari–Letojanni Fault System (ATLFS), two nearly SE-striking fault systems crossing northeastern Sicily and ending on the Ionian shoreline of Sicily according to many investigators. Within this set of faults, most of the deformation/seismicity occurs along the northern and central segments of ATLFS, compared to lowactivity along TFS. A lack of seismicity (both recent and historical) is observed in the southern sector of ATLFS where, however, geodetic data reveal significant deformation. Ourmultidisciplinary dataset including offshore observations suggests the southeastward continuation of the ATLFS into the Ionian Sea until joiningwith the faults cutting the Ionian accretionarywedge described in the recent literature. Our findings imply the existence of a highly segmented crustal shear zone extending from the Aeolian Islands to the Ionian Abyssal plain, that we believe plays the role of accommodating differential motion between the Southern Tyrrhenian unit and the western compressional domain of Sicily. The ATLFS, which is a main part of the inferred shear zone, behaves similarly to what often observed at the edges of retreating subduction
    Description: Published
    Description: 205-218
    Description: 1T. Geodinamica e interno della Terra
    Description: 2T. Tettonica attiva
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: 6A. Monitoraggio ambientale, sicurezza e territorio
    Description: JCR Journal
    Description: restricted
    Keywords: subduction edge ; seismic velocity structure ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.02. Exploration geophysics::04.02.02. Gravity methods ; 04. Solid Earth::04.02. Exploration geophysics::04.02.04. Magnetic and electrical methods ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods ; 04. Solid Earth::04.03. Geodesy::04.03.99. General or miscellaneous ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.03. Geodesy::04.03.03. Gravity and isostasy ; 04. Solid Earth::04.03. Geodesy::04.03.04. Gravity anomalies ; 04. Solid Earth::04.03. Geodesy::04.03.05. Gravity variations ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.05. Geomagnetism::04.05.99. General or miscellaneous ; 04. Solid Earth::04.05. Geomagnetism::04.05.03. Global and regional models ; 04. Solid Earth::04.05. Geomagnetism::04.05.04. Magnetic anomalies ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.04. Plate boundaries, motion, and tectonics ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.06. Subduction related processes ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 20
    Publication Date: 2017-04-04
    Description: The Dead Sea Transform (DST) fault system,where a lateral displacement between the African and Arabian plates occurs, is characterised by anomalous heat flux in the Israeli area close to the border with Syria and Jordan. The concentration of He and CO2, and isotopic composition of He and total dissolved inorganic carbon were studied in cold and thermalwaters collected along the DST, in order to investigate the source of volatiles and their relationship with the tectonic framework of the DST. The waters with higher temperature (up to 57.2 °C) are characterised by higher amounts of CO2 and helium (up to 55.72 and 1.91 ∗ 10−2 cc l−1, respectively). Helium isotopic data (R/Ra from 0.11 to 2.14) and 4He/20Ne ratios (0.41–106.86) show the presence of deep-deriving fluids consisting of a variable mixture ofmantle and crust end-members,with the former reaching up to 35%. Carbon isotope signature of total dissolved carbon from hot waters falls within the range of magmatic values, suggesting the delivery of deep-seated CO2. The geographical distribution of helium isotopic data and isotopic carbon (CO2) values coupled with (CO2/3He ratios) indicate a larger contribution of mantle-derived fluids affecting the northern part of the investigated area, where the waters reach the highest temperature. These evidences suggest the occurrence of a favourable tectonic framework, including a Moho discontinuity up-rise and/or the presence of a deep fault system coupled with the recent magmatic activity recognised in the northern part of Israel.
    Description: Published
    Description: 50–57
    Description: 4V. Vulcani e ambiente
    Description: JCR Journal
    Description: restricted
    Keywords: Dead Sea Fault ; Fluid geochemistry ; Dissolved gases ; Helium isotopes ; Carbon isotopes ; 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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 21
    Publication Date: 2023-12-04
    Description: Early in the morning of 24 August, 2013, following by hours the drilling of a shallowborehole in the same spot, a new fumarole producing emissions of CO2-rich gas, water, and mud suddenly appeared at a crossroad along the fenced area of the Fiumicino international airport of Rome, Italy. Similar episodes have been scientifically documented or simply reported in recent and past years. To understandwhy gases are easily entrapped in the shallow subsurface of the Fiumicino area, we used five borehole cores drilled by us, analyzed the stratigraphy of these and other nearby cores, acquired a 2D seismic refraction tomogram, and performed chemical and isotopic analyses of water samples collected from aquifers intercepted by two drilled boreholes. Our boreholes were realized with proper anti-gasmeasures as,while drilling, we recorded the presence of pressurized gases at a specific permeable gravel level. Results showthat, in the study area, gases become mainly entrapped in a mid-Pleistocene gravel horizon at about 40–50 m depth. This horizon contains a confined aquifer that stores the endogenous upwelling gases. The gravel is interposed between two silty–clayey units. The lower unit, very hard and overconsolidated, is affected by fractures that allow ascending gases to bypass the otherwise impermeable shale, permeate the gravel, and dissolve into the aquifer. In contrast, the upper unit is impermeable to fluids and seals the gaspressurized aquifer, which therefore constitutes a source of hazard during human activities such as well drilling, quarrying, and various building-related excavations. As the stratigraphy of the Fiumicino area is very common in large portions of the densely populated Roman area and as the adjacent volcanic districts are hydrothermally active, we conclude that phenomena similar to that observed at Fiumicino could again occur both at Fiumicino and elsewhere in the surrounding region. As a prompt confirmation of our conclusion, we signal that, while writing this paper, new artificially-triggered degassing phenomena occurred off Fiumicino in connection with the construction of the new harbor.
    Description: Published
    Description: 53-66
    Description: 4V. Vulcani e ambiente
    Description: JCR Journal
    Description: restricted
    Keywords: Mud volcano ; gas hazard ; drilling ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 22
    Publication Date: 2024-05-09
    Description: The genetic relationship between carbon-bearing species (CO, CO2, CH4, C2H6, C3H8, C2H4 and C3H6) was investigated in volcanic-hydrothermal gases emitted from Nisyros (Greece), Vesuvio, La Solfatara (Campi Flegrei) and Pantelleria (all Italy). Apparent carbon isotopic temperatures of the CH4-CO2 system are ~360°C at Nisyros, 420-460°C at Vesuvio, ~450°C at La Solfatara and ~540°C at Pantelleria. These temperatures are confirmed by measured propene/propane and H2/H2O concentration ratios. CH4 and CO2 equilibrate in the single liquid phase prior to the onset of boiling, whereas propene and propane attain equilibrium in the saturated water vapor phase. Boiling in these high-enthalpy hydrothermal systems might occur isothermally. Once vapor has been extracted from the parental liquid, CO/CO2 responds most sensitively to the temperature gradient encountered by the ascending gases. Our results imply that the CH4-CO2 isotopic geothermometer can provide reliable information about temperatures of deep hydrothermal liquids associated with volcanism. Propene/propane and H2/H2O concentration ratios should be measured along with the carbon isotopic composition of CO2 and CH4 to provide independent constraints on the geological significance of the apparent carbon isotopic temperatures.
    Description: Published
    Description: 66–75
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: restricted
    Keywords: Hydrocarbons ; Hydrothermal fluids ; Volcanoes ; Geothermometry ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 23
    Publication Date: 2024-05-09
    Description: The Principal Cordillera of Central Chile is characterized by two belts of different ages and lithologies: (i) an eastern Mesozoic belt, consisting of limestone- and gypsum-rich sedimentary rocks at the border between Central Chile and Argentina, where the active volcanic arc occurs; and (ii) a western belt of Cenozoic age containing basaltic to andesitic volcanic and volcanoclastic sequences. This distinctive geological setting controls water chemistry of cold and thermal springs in the region, which are fed by meteoric water that circulates through deep regional structures. In the western sector of Principal Cordillera, water–rock interaction processes produce lowTDS, slightly alkaline HCO3 − dominatedwaters, although dissolution of underlyingMesozoic evaporitic rocks occasionally causes SO4 2− and Cl− enrichments. In this area, few Na+–HCO3 − and Na+–SO4 2− waters occurred, being likely produced by a Ca2+–Na+ exchange during water–rock interactions. Differently, the chemical features of Ca2+–Cl−waterswas likely related to an albitization–chloritization process affecting basaltic to andesitic rocks outcropping in this area. Addition of Na+–Cl− brines uprising from the eastern sector through the westverging thrust faults cannot be excluded, as suggested by the occurrence of mantle He (~19%) in dissolved gases. In contrast, in the eastern sector of the study region, mainly characterized by the occurrence of evaporitic sequences and relatively high heat flow,mature Na+–Cl− waters were recognized, the latter being likely related to promising geothermal reservoirs, as supported by the chemical composition of the associated bubbling and fumarolic gases. Their relatively low3He/4He ratios (up to 3.9 Ra)measured in the fumaroles on this area evidenced a significant crustal contamination by radiogenic 4He. The latter was likely due to (i) degassing from 4He-rich magma batches residing in the crust, and/or (ii) addition of fluids interacting with sedimentary rocks. This interpretation is consistent with the measured δ13C-CO2 values (from−13.2 to−5.72‰vs. V-PDB) and the CO2/3He ratios (up to 14.6 × 1010), which suggest that CO2 mostly originates from the limestone-rich basement and recycling of subducted sediments,with an important addition of sedimentary (organic-derived) carbon,whereas mantle degassing contributes at a minor extent. According to geothermometric estimations based on the Na+, K+, Mg2+ and Ca2+ contents, the mature Na+–Cl− rich waters approached a chemical equilibrium with calcite, dolomite, anhydrite, fluorite, albite, K-feldspar and Ca- andMg-saponites at a broad range of temperatures (up to ~300 °C) In the associated gas phase, equilibria of chemical reactions characterized by slowkinetics (e.g. sabatier reaction) suggested significant contributions from hot and oxidizing magmatic gases. This hypothesis is consistent with the δ13C-CO2, Rc/Ra, CO2/3He values of the fumarolic gases. Accordingly, the isotopic signatures of the fumarolic steam is similar to that of fluids discharged from the summit craters of the two active volcanoes in the study area (Tupungatito and Planchón–Peteroa). These results encourage the development of further geochemical and geophysical surveys aimed to provide an exhaustive evaluation of the geothermal potential of these volcanic–hydrothermal systems.
    Description: Published
    Description: 97-113
    Description: 1V. Storia e struttura dei sistemi vulcanici
    Description: JCR Journal
    Description: restricted
    Keywords: Fluid geochemistry ; Central Chile ; Water–gas–rock interaction ; Hydrothermal reservoir ; Geothermal resource ; Volcanoes ; 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
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  • 24
    Publication Date: 2024-05-09
    Description: The Vicano–Cimino Volcanic District (VCVD) is related to the post-orogenic magmatic activity of the peri- Tyrrhenian sector of Central Italy. The chemical and isotopic compositions of 333 water discharges and 25 gas emissions indicate the occurrence of two main sources: 1) cold Ca-HCO3 to Ca(Na, K)-HCO3 type waters from relatively shallow aquifers hosted in volcanic and sedimentary formations; and 2) thermal Ca-SO4(HCO3) type waters located in a deep CO2-pressurized reservoir, hosted in carbonate–evaporite rocks and separated from the shallow aquifers by thick sequences of low-permeability formations. Carbon dioxide is mainly produced by thermal metamorphic decarbonation within the deepest and hottest parts of the carbonate–evaporite reservoir (δ13C–CO2 from−3.1 to+2.2‰vs. VPDB), likely affected by a mantle-rooted CO2. ReleaseofCO2-rich gases from the deep aquifer into the overlying shallow aquifers produces high-CO2 springs and bubbling pools. The spatial distribution of thermal waters and CO2-rich cold discharges is strongly controlled by fractures and faults located in correspondencewith buried structural highs. Stable isotopes (δD and δ18O) suggest thatmeteoric water feeds both the shallowand deep reservoirs. The relatively lowR/Ra values (0.27–1.19) indicate that He ismainly deriving from a crustal source, with minor component from the mantle affected by crustal contamination related to the subduction of the Adriatic plate. Consistently, relatively high N2/Ar and N2/3He ratios and positive δ15N–N2 values (from0.91 to 5.7‰vs. air) characterize the VCVD gas discharges, suggesting the occurrence of a significant “excess” nitrogen. Isotopic compositions of CH4 (δ13C–CH4 and δD–CH4 values from−28.9 to−22.1‰vs. VPDB and from −176 to −138‰ vs. VSMOW, respectively), and composition of light alkanes are indicative of prevalent thermogenic CH4, although the occurrence of abiogenic CH4 production cannot be excluded. The δ34S–H2S values (from+9.3 to+11.4‰vs. VCDT) are consistentwith the hypothesis of H2S production fromthermogenic reduction of Triassic anhydrites. Gas geothermometry in the H2O–H2–Ar–H2S system suggests that the VCVD gases equilibrated in a liquid phase at redox conditions controlled by interactions of fluids with the local mineral assemblage at temperatures lower (b200 °C) than that andmeasured in deep (N2000 m) geothermalwells. This confirms that secondary processes, i.e. steam condensation, gas dissolution in shallow aquifers, re-equilibration at lower temperature, and microbial activity, significantly affect the chemistry of the uprising fluids. Thermal water chemistry supports the occurrence in this area of an anomalous heat flowthat, coupledwith the recent demographic growth, makes this site suitable for direct and indirect exploitation of the geothermal resource, in agreement with the preliminary surveys carried out in the 1970's–1990's for geothermal exploration purposes.
    Description: Published
    Description: 96-114
    Description: 5A. Energia e georisorse
    Description: JCR Journal
    Description: restricted
    Keywords: geothermal resources ; 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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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