Articles de revues : « Fumarolic gas »

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Ohba, Takeshi, Muga Yaguchi, Kana Nishino et Nozomi Numanami. « Time Variation in the Chemical and Isotopic Composition of Volcanic Gas at Mt. Mihara of Izu-Oshima Island, Japan ». Journal of Disaster Research 14, n^o 7 (1 octobre 2019) : 972–77. http://dx.doi.org/10.20965/jdr.2019.p0972.

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Volcanic gas was sampled at three fumaroles and one borehole on Mt. Mihara, Izu-Oshima volcano. The fumarolic gas and the borehole steam possessed an excess enthalpy relative to the air saturated with water vapor. The fumarolic gas located west of the pit crater on Mt. Mihara showed a time variation in chemical and isotopic composition. The cause of the variation seems to be an enhancement of water vapor condensation. No similar variation was observed in the fumarolic gas located east of the pit crater, suggesting the above variation is a phenomena localized around the western fumarole. Hydrogen gas was detected in the sampled gases with low concentration. The change in the H2 concentration synchronized among the three fumaroles, suggesting the H2 gas originated in the hydrothermal system developed beneath Mt. Mihara.

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Sandalov, F. D., N. V. Schipalkina, I. V. Pekov, N. N. Koshlyakova, S. N. Britvin et E. G. Sidorov. « Cristobalite and tridymite from deposits of the Arsenatnaya fumarole (Tolbachik volcano, Kamchatka, Russia) ». Moscow University Bulletin. Series 4. Geology 1, n^o 2 (28 janvier 2022) : 87–96. http://dx.doi.org/10.33623/0579-9406-2021-2-87-96.

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This article displays data on cristobalite and tridymite from the Arsenatnaya active fumarole, the Tolbachik volcano, Kamchatka, Russia. The minerals occur in associations with fumarolic sylvite, sanidine, cassiterite, hematite, pseudobrookite, johillerite, tilasite, badalovite. Fumarolic cristobalite is tetragonal (-modification); the unit-cell parameters for one of samples are: а = 4,975 (7) Å, с = 6,944 (13) Å, V = 171,89 Å3. There are two types of tridymite — monoclinic (MC) and orthorhombic (PO-10) — in the Arsenatnaya fumarole. The unit-cell parameters of these tridymite modifications are: a = 18,553 (5), b = 5,006 (1), с = 25,952 (10) Å, = 117,68 (2)o, V = 2134,3 (11) Å3 (MC); a = 9,941 (2), b = 17,165 (4), с = 82,362 (18) Å, V = 14053,4 (29) Å3 (PO-10). Mineral assemblages of cristobalite and tridymite indicate high-temperature formation conditions of these minerals — not lower 450–500 °С — with a high participation degree of HCl and HF in process of basalt alteration by fumarolic gas. The surrounding basalt was a source of silicon. This element was, probably, transported in the form of SiX4, where X = F, Cl.

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Shchipalkina, Nadezhda V., Igor V. Pekov, Natalia N. Koshlyakova, Sergey N. Britvin, Natalia V. Zubkova, Dmitry A. Varlamov et Eugeny G. Sidorov. « Unusual silicate mineralization in fumarolic sublimates of the Tolbachik volcano, Kamchatka, Russia &#8211 ; Part 2 : Tectosilicates ». European Journal of Mineralogy 32, n^o 1 (29 janvier 2020) : 121–36. http://dx.doi.org/10.5194/ejm-32-121-2020.

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Abstract. This second of two companion articles devoted to silicate mineralization in fumaroles of the Tolbachik volcano (Kamchatka, Russia) reports data on chemistry, crystal chemistry and occurrence of tectosilicates: sanidine, anorthoclase, ferrisanidine, albite, anorthite, barium feldspar, leucite, nepheline, kalsilite, sodalite and hauyne. Chemical and genetic features of fumarolic silicates are also summarized and discussed. These minerals are typically enriched with “ore” elements (As, Cu, Zn, Sn, Mo, W). Significant admixture of As5+ (up to 36 wt % As2O5 in sanidine) substituting Si is the most characteristic. Hauyne contains up to 4.2 wt % MoO3 and up to 1.7 wt % WO3. All studied silicates are hydrogen-free, including mica and amphiboles which are F-rich. Iron-bearing minerals contain only Fe3+ due to strongly oxidizing formation conditions. In Tolbachik fumaroles, silicates were formed in the temperature range 500–800 ∘C as a result of direct deposition from the gas phase (as volcanic sublimates) or gas–rock interactions. The zonation in distribution of major silicate minerals observed in a vertical section of the Arsenatnaya fumarole, from deep (the hottest) to upper parts is diopside + forsterite + enstatite + andradite → diopside → fluorophlogopite + diopside → sanidine + fluorophlogopite → sanidine. This is in agreement with volatilities of major species-defining metals in volcanic gases. From a crystal-chemical viewpoint, this series corresponds to the following sequence of crystallization of minerals with temperature decrease: nesosilicates → inosilicates → phyllosilicates → tectosilicates.

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Bitskiy, R. R. « ADVANCED METHODS FOR THE EXTRACTION OF USEFUL COMPONENTS FROM VOLCANIC GASES ». Mining science and technology, n^o 4 (28 février 2018) : 3–12. http://dx.doi.org/10.17073/2500-0632-2017-4-3-11.

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Technical progress is impossible without the creation of new devices, the quantitative and qualitative indicators of which radically differ from the known ones, which in turn requires new technologies and materials. In the creation of new materials, rare and rare-earth metals are increasingly used, the reserves of which are very limited. Therefore, the development and implementation of new methods of mining such metals are a timely and urgent task.Prospective methods of mining mineral deposits from volcanic gases are considered. The proposed model makes it possible to reveal the composition of volcanic gas, to experimentally prove its dynamic properties, to develop a model that allows one to trace the behavior of gas, on its basis to develop a principle scheme for extracting rare-earth elements (REE) and to present the hardwaretechnological scheme for obtaining REE from fumaroles (types of gas) in the form fumarolic metallurgical plant.On the basis of a model system with heavy metal solutions in a liquid, the possibility of studying the behavior of gas particles is shown. Such a model system is converted to volcanic gas and allows interpretation of the results for a fumarolic metallurgical unit (FMU) by determining the critical dimensions of the elements of such an installation (dome sizes, parameters of connecting hoses).

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Aguilera, Felipe, Susana Layana, Augusto Rodríguez-Díaz, Cristóbal González, Julio Cortés et Manuel Inostroza. « Hydrothermal alteration, fumarolic deposits and fluids from Lastarria Volcanic Complex : A multidisciplinary study ». Andean Geology 43, n^o 2 (20 mai 2016) : 166. http://dx.doi.org/10.5027/andgeov43n2-a02.

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A multidisciplinary study that includes processing of Landsat ETM+ satellite images, chemistry of gas condensed, mineralogy and chemistry of fumarolic deposits, and fluid inclusion data from native sulphur deposits, has been carried out in the Lastarria Volcanic Complex (LVC) with the objective to determine the distribution and characteristics of hydrothermal alteration zones and to establish the relations between gas chemistry and fumarolic deposits. Satellite image processing shows the presence of four hydrothermal alteration zones, characterized by a mineral assemblage constituted mainly by clay minerals, alunite, iron oxides, and more subordinated ferrous minerals and goethite. Hydrothermal alteration zones present in the Lastarria sensu stricto volcano are directly related to the recent fumarolic activity. Geochemistry of fumarolic gas condensed, obtained from two fumaroles at temperatures between 328 and 320 °C, has allowed detecting 37 diverse elements corresponding to halogens, chalcophiles, siderophiles, alkali metals, alkali earth metals and Rare Earth Elements (REE), with concentrations that vary widely between 5,620 ppm (chlorine) and 0.01 ppm (Mo, Ag, Sn, Pb, Se, Mg and Cr). Logarithm of Enrichment Factor (log EFi) for each element present values between 6.35 (iodine) and<1 (K, Na, Ca, Fe and Al). Those elements are originated primarily from a magmatic source, whereas at shallow level a hydrothermal source contributes typical rock-related elements, which are leached from the wall rock by a strong interaction with hyperacid fluids. Mostly of elements detected are transported to the surface in the fumarolic emissions as gaseous species, while very few elements (Mg, Ca and Al) are transported in silicate aerosols. A wide spectrum of minerals are present in the fumarolic deposits, which are constituted by sublimates and incrustations, and the main minerals phases are distributed in six mineral families, corresponding to sulphates, hydrated sulphates, sulphides, halides, carbonates, silicates and native element minerals. The sublimate/incrustation minerals are dominated by the presence of sulphate, sulphur, chlorine and diverse rock-related elements, which are formed by processes that include a. oxidation of gaseous phase; b. strong rock-fluid interaction; c. dissolution of silicate minerals and volcanic glass; d. gas-water interaction; e. deposition/precipitation of saline bearing minerals; f. oxidation of sublimates/incrustations to form secondary minerals and g. remobilization of sulphur deposits by meteoric water. Despite that sublimate/ incrustation minerals are dominated by rock-related elements, its chemistry shows high contents of high-volatile elements as As, Sb, Cd, among others. Fluid inclusions studies carried out in thin pseudobanded native sulphur from fumarolic deposits, by use of Raman and infrared spectroscopy combined with microthermometry analyses, provided evidence of H2O, CO2, H2S, SO4, COS bearing fluids, homogenization temperatures around 110 °C and salinities varying from ~11 to ~7 wt% NaCl. Fluid inclusions data show also evidences of a mixing (dilution) between hot and saline fluid with a cooler fluid (cold groundwater or a steam-heated water) as the main process.

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Stenner, Christian, Andreas Pflitsch, Lee Florea, Kathleen Graham et Eduardo Cartaya. « Development and persistence of hazardous atmospheres in a glaciovolcanic cave system—Mount Rainier, Washington, USA ». Journal of Cave and Karst Studies 84, n^o 2 (30 juin 2022) : 66–82. http://dx.doi.org/10.4311/2021ex0102.

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Glaciovolcanic cave systems, including fumarolic ice caves, can present variable atmospheric hazards. The twin summit craters of Mount Rainier, Washington, USA, host the largest fumarolic ice cave system in the world. The proximity of fumarole emissions in these caves to thousands of mountaineers each year can be hazardous. Herein we present the first assessment and mapping of the atmospheric hazards in the Mount Rainier caves along with a discussion on the microclimates involved in hazard formation and persistence. Our results are compared to applicable life-safety standards for gas exposure in ambient air. We also describe unique usage of Self-Contained Breathing Apparatus (SCBA) at high altitude. In both craters, subglacial CO2 traps persist in multiple locations due to fumarole output, limited ventilation, and cave morphology. CO2 concentrations, calculated from O2 depletion, reached maximum values of 10.3 % and 24.8 % in the East and West Crater Caves, respectively. The subglacial CO2 lake in West Crater Cave was persistent, with atmospheric pressure as the main factor influencing CO2 concentrations. O2 displacement exacerbated by low O2 partial pressure at the high summit altitude revealed additional cave passages that can be of immediate danger to life and health (IDLH), with O2 partial pressures as low as 68.3 mmHg. Planning for volcanic research or rescue in or around similar cave systems can be assisted by considering the implications of atmospheric hazards. These findings highlight the formation mechanisms of hazardous atmospheres, exploration challenges, the need for mountaineering and public awareness, and the broader implications to volcanic hazard assessment and research in these environments.

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Kusakabe, Minoru, Keisuke Nagao, Takeshi Ohba, Jung Hun Seo, Sung-Hyun Park, Jong Ik Lee et Byong-Kwon Park. « Noble gas and stable isotope geochemistry of thermal fluids from Deception Island, Antarctica ». Antarctic Science 21, n^o 3 (11 février 2009) : 255–67. http://dx.doi.org/10.1017/s0954102009001783.

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AbstractNew stable isotope and noble gas data obtained from fumarolic and bubbling gases and hot spring waters sampled from Deception Island, Antarctica, were analysed to constrain the geochemical features of the island's active hydrothermal system and magmatism in the Bransfield back-arc basin. The 3He/4He ratios of the gases (< 9.8 × 10-6), which are slightly lower than typical MORB values, suggest that the Deception Island magma was generated in the mantle wedge of a MORB-type source but the signature was influenced by the addition of radiogenic 4He derived from subducted components in the former Phoenix Plate. The N2/He ratios of fumarolic gas are higher than those of typical mantle-derived gases suggesting that N2 was added during decomposition of sediments in the subducting slab. The δ13C values of -5 to -6‰ for CO2 also indicate degassing from a MORB-type mantle source. The H2/Ar- and SiO2 geothermometers indicate that the temperatures in the hydrothermal system below Deception Island range from ~150°C to ~300°C. The δD and δ18O values measured from fumarolic gas and hot spring waters do not indicate any contribution of magmatic water to the samples. The major ionic components and δD-δ18O-δ34S values indicate that hot spring waters are a mixture of local meteoric water and seawater. Mn and SiO2 in spring waters were enriched relative to seawater reflecting water-rock interaction at depth.

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Matsu’ura, Kouki, Akihiko Terada, Toshiya Mori et Takato Ono. « A Simple Method for the Analysis of Fumarolic Gases Using Response-Adjusted Sensors with a UAV ». Journal of Disaster Research 17, n^o 5 (1 août 2022) : 620–29. http://dx.doi.org/10.20965/jdr.2022.p0620.

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Recent developments in unmanned aerial vehicle (UAV) technology have made it possible to measure gas compositions in volcanic plumes using lightweight compact gas sensors. However, the differences in the responses of each gas sensor can be critical in estimating gas compositions based on regression scatter plots, particularly for small plumes emitted during volcanic unrest and non-eruption periods. Based on the laboratory experiments, we show that air blowers easily adjust sensor responses and improve correlation on regression scatter plots, allowing quick composition estimates without the use of mathematical applications. Applying our measurement system, lightweight compact gas sensors for H2S, SO2, CO2, and H2O, with air blowers suspended from a UAV, were used to determine the compositions of a small plume at Io-yama, Kirishima volcano, Japan. The compositions of the plume estimated by our system were reasonably consistent with those obtained by laboratory analysis of volcanic gas collected at ground level near the vent, with fluctuations in CO2 ratios and lower H2O ratios, relative to other gases, being observed. For more accurate estimations of CO2 and H2O concentrations, low humidity conditions at a distance from the fumarole are preferable for analysis of plumes diluted by ambient dry air. Our measurement system is simple, easy to set up, and useful for estimating the compositions of small passive fumarolic gas plumes during volcanic unrest and non-eruption periods, without mathematical applications.

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Glover, Richard B., Edward K. Mroczek et J. Bruce Finlayson. « Fumarolic gas chemistry at Wairakei, New Zealand, 1936–1998 ». Geothermics 30, n^o 5 (octobre 2001) : 511–25. http://dx.doi.org/10.1016/s0375-6505(01)00006-2.

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Sano, Yuji, et Bernard Marty. « Origin of carbon in fumarolic gas from island arcs ». Chemical Geology 119, n^o 1-4 (janvier 1995) : 265–74. http://dx.doi.org/10.1016/0009-2541(94)00097-r.

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Tamburello, Moune, Allard, Venugopal, Robert, Rosas-Carbajal, Deroussi et al. « Spatio-Temporal Relationships between Fumarolic Activity, Hydrothermal Fluid Circulation and Geophysical Signals at an Arc Volcano in Degassing Unrest : La Soufrière of Guadeloupe (French West Indies) ». Geosciences 9, n^o 11 (15 novembre 2019) : 480. http://dx.doi.org/10.3390/geosciences9110480.

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： Over the past two decades, La Soufrière volcano in Guadeloupe has displayed a growing degassing unrest whose actual source mechanism still remains unclear. Based on new measurements of the chemistry and mass flux of fumarolic gas emissions from the volcano, here we reveal spatio-temporal variations in the degassing features that closely relate to the 3D underground circulation of fumarolic fluids, as imaged by electrical resistivity tomography, and to geodetic-seismic signals recorded over the past two decades. Discrete monthly surveys of gas plumes from the various vents on La Soufrière lava dome, performed with portable MultiGAS analyzers, reveal important differences in the chemical proportions and fluxes of H2O, CO2, H2S, SO2 and H2, which depend on the vent location with respect to the underground circulation of fluids. In particular, the main central vents, though directly connected to the volcano conduit and preferentially surveyed in past decades, display much higher CO2/SO2 and H2S/SO2 ratios than peripheral gas emissions, reflecting greater SO2 scrubbing in the boiling hydrothermal water at 80–100 m depth. Gas fluxes demonstrate an increased bulk degassing of the volcano over the past 10 years, but also a recent spatial shift in fumarolic degassing intensity from the center of the lava dome towards its SE–NE sector and the Breislack fracture. Such a spatial shift is in agreement with both extensometric and seismic evidence of fault widening in this sector due to slow gravitational sliding of the southern dome sector. Our study thus provides an improved framework to monitor and interpret the evolution of gas emissions from La Soufrière in the future and to better forecast hazards from this dangerous andesitic volcano.

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Shevko, E. P., S. B. Bortnikova, N. A. Abrosimova, V. S. Kamenetsky, S. P. Bortnikova, G. L. Panin et M. Zelenski. « Trace Elements and Minerals in Fumarolic Sulfur : The Case of Ebeko Volcano, Kuriles ». Geofluids 2018 (2018) : 1–16. http://dx.doi.org/10.1155/2018/4586363.

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Native sulfur deposits on fumarolic fields at Ebeko volcano (Northern Kuriles, Russia) are enriched in chalcophile elements (As-Sb-Se-Te-Hg-Cu) and contain rare heavy metal sulfides (Ag2S, HgS, and CuS), native metal alloys (Au2Pd), and some other low-solubility minerals (CaWO4, BaSO4). Sulfur incrustations are impregnated with numerous particles of fresh and altered andesite groundmass and phenocrysts (pyroxene, magnetite) as well as secondary minerals, such as opal, alunite, and abundant octahedral pyrite crystals. The comparison of elemental abundances in sulfur and unaltered rocks (andesite) demonstrated that rock-forming elements (Ca, K, Fe, Mn, and Ti) and other lithophile and chalcophile elements are mainly transported by fumarolic gas as aerosol particles, whereas semimetals (As, Sb, Se, and Te), halogens (Br and I), and Hg are likely transported as volatile species, even at temperatures slightly above 100°C. The presence of rare sulfides (Ag2S, CuS, and HgS) together with abundant FeS2 in low-temperature fumarolic environments can be explained by the hydrochloric leaching of rock particles followed by the precipitation of low-solubility sulfides induced by the reaction of acid solutions with H2S at ambient temperatures. The elemental composition of native sulfur can be used to qualitatively estimate elemental abundances in low-temperature fumarolic gases.

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Lee, Hsiao-Fen, Tsanyao Frank Yang, Tefang Faith Lan, Sheng-Rong Song et Shuhjong Tsao. « Fumarolic Gas Composition of the Tatun Volcano Group,Northern Taiwan ». Terrestrial, Atmospheric and Oceanic Sciences 16, n^o 4 (2005) : 843. http://dx.doi.org/10.3319/tao.2005.16.4.843(gig).

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Mori, Takehiko, Takashi Suzuki, Jun’ichi Hirabayashi, Kenji Nogami, Michiko Ohwada et Shin Yoshikawa. « Depth estimation of fumarolic gas source deduced by fume pressure measurement ». Earth, Planets and Space 60, n^o 8 (août 2008) : 889–93. http://dx.doi.org/10.1186/bf03352842.

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Yoshikawa, Hideki, Hiromichi Nakahara, Mineo Imamura, Kouichi Kobayashi et Takashi Nakanishi. « Determination of 14C in Volcanic Gas By Accelerator Mass Spectrometry ». Radiocarbon 47, n^o 2 (2005) : 211–19. http://dx.doi.org/10.1017/s0033822200019718.

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Radioactive nuclides such as radiocarbon can be good tracers for investigating the circulation of underground carbon and water. Volcanic gas can be sampled reliably for 14C analysis and prepared for analysis by accelerator mass spectrometry (AMS). In this paper, we establish a method for the measurement of 14C in volcanic gas, and measure the amounts of 14C in various volcanic gases. Samples of fumarolic gas from some Japanese volcanoes were found to contain 0.5 to 4.2 pMC, while those from White Island in New Zealand contained 2.6 pMC. Dissolved gas from Lake Nyos, Cameroon, contained 0.4 to 4.8 pMC. The data indicate a mixing process between surface carbon and deep carbon.

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Kiyosu, Yasuhiro, et Yasunori Okamoto. « Variation in fumarolic H2 gas and volcanic activity at Nasudake in Japan ». Journal of Volcanology and Geothermal Research 80, n^o 1-2 (janvier 1998) : 27–37. http://dx.doi.org/10.1016/s0377-0273(97)00039-5.

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Kyriakopoulos, G. K. « NATURAL DEGASSING OF CARBON DIOXIDE AND HYDROGEN SULPHIDE AND ITS ENVIRONMENTAL IMPACT AT MILOS ISLAND, GREECE ». Bulletin of the Geological Society of Greece 43, n^o 5 (31 juillet 2017) : 2361. http://dx.doi.org/10.12681/bgsg.11636.

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The Aegean region represents an active convergent zone, where continental micro-plates exhibit a complex interaction between the African and the Eurasian plates. The calc-alkaline volcanic activity of the Southern Aegean region developed in various volcanic centers from Soussaki to Nisyros through Methana-Poros, Milos and Santorini. Milos Island has been an active volcano till the middle of Quaternary and is at present characterized by a high enthalpy geothermal system. The volcanism started 3.5 Ma ago and still continues up today in the form of post-volcanic manifestations. Most quiescent volcanoes released large amounts of CO2 and H2S through fumarolic activity and soil diffuse degassing. Numerous small fumaroles occur in various places, mainly at Kalamos and Adamas volcanic areas. Also along the southern coast of the island there are volcanic gas manifestations in the sea. Gases were sampled from fumaroles at Kalamos area as well as from north east part of Adamas village. Furthermore many soil gases were sampled at 50 cm depth and analyzed for their chemical composition. Apart from atmospheric gases (N2 and O2), which sometimes contaminate the samples, the main gas phase is CO2. Sometimes also H2S, CH4 and H2 are present in high amounts while CO and He are always present in trace amounts. The He isotopic composition highlights a significant mantle component. CO2 and H2S concentrations higher than in the normal atmosphere can be stimulating for plant growth until certain levels and detrimental above them. As for many active geothermal areas of the world also H2S and CO2 concentrations measured in the area of Milos could be of concern for human health.

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Inguaggiato, Salvatore, Fabio Vita, Iole Serena Diliberto, Agnes Mazot, Lorenzo Calderone, Andrea Mastrolia et Marco Corrao. « The Extensive Parameters as a Tool to Monitoring the Volcanic Activity : The Case Study of Vulcano Island (Italy) ». Remote Sensing 14, n^o 5 (5 mars 2022) : 1283. http://dx.doi.org/10.3390/rs14051283.

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On Vulcano Island (Italy), many geochemical crises have occurred during the last 130 years of solfataric activity. The main crises occurred in 1978–1980, 1988–1991, 1996, 2004–2007, 2009–2010 and the ongoing 2021 anomalous degassing activity. These crises have been characterized by early signals of resuming degassing activity, measurable by the increase of volatiles and energy output emitted from the summit areas of the active cone, and particularly by increases of gas/water ratios in the fumarolic area at the summit. In any case, a direct rather than linear correspondence has been observed among the observed increase in the fluid output, seismic release and ground deformation, and is still a subject of study. We present here the results obtained by the long-term monitoring (over 13 years of observations) of three extensive parameters: the SO2 flux monitored in the volcanic plume, the soil CO2 flux and the local heat flux, monitored in the mild thermal anomaly located to the east of the high-temperature fumarole. The time variations of these parameters showed cyclicity in the volcanic degassing and a general increase in the trend in the last period. In particular, we focused on the changes in the mass and energy output registered in the period of June–December 2021, to offer in near-real-time the first evaluation of the level and duration of the actual exhalative crisis affecting Vulcano Island. In this last event, a clear change in degassing style was recorded for the volatiles emitted by the magma. For example, the flux of diffused CO2 from the soils reached the maximum never-before-recorded value of 34,000 g m−2 d−1 and the flux of SO2 of the plume emitted by the fumarolic field on the summit crater area reached values higher than 200 t d−1. The interpretation of the behavior of this volcanic system, resulting from the detailed analyses of these continuous monitoring data, will complete the framework of observations and help in defining and possibly forecasting the next evolution of the actual exhaling crisis.

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Rodríguez, A., et M. J. van Bergen. « Volcanic hydrothermal systems as potential analogues of Martian sulphate-rich terrains ». Netherlands Journal of Geosciences - Geologie en Mijnbouw 95, n^o 2 (8 avril 2015) : 153–69. http://dx.doi.org/10.1017/njg.2015.12.

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AbstractRemote sensing observations and rover missions have documented the presence of sulphate-rich mineral associations on Mars. Many of these minerals are paleo-indicators of hydrous, acidic and oxidising environments that must have prevailed in Mars´ distant past, contrary to the present conditions. Furthermore, occurrences of silica together with high Cl and Br concentrations in Martian soils and rocks represent fingerprints of chemically atypical fluids involved in processes operating on the surface or at shallow depth. From field observations at representative active volcanoes in subduction settings, supported by geochemical modelling, we demonstrate that volcanic hydrothermal systems are capable of producing Mars-like secondary mineral assemblages near lakes, springs and fumaroles through the action of acidic fluids. Water–gas-rock interactions, together with localised flow paths of water and fumarolic gas emitted from associated subaerial vents, lead to deposition of a range of sulphates, including gypsum, jarosite, alunite, epsomite and silica. Evaporation, vapour separation and fluid mixing in (near-) surface environments with strong gradients in temperature and fluid chemistry further promote the diversity of secondary minerals. The mineralogical and chemical marks are highly variable in space and time, being subject to fluctuations in ambient conditions as well as to changes in the status of volcanic-hydrothermal activity. It is concluded that active processes in modern volcanic-geothermal systems may be akin to those that created several of the sulphate-rich terrains in the early history of Mars.

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Giggenbach, W. F. « Redox processes governing the chemistry of fumarolic gas discharges from White Island, New Zealand ». Applied Geochemistry 2, n^o 2 (mars 1987) : 143–61. http://dx.doi.org/10.1016/0883-2927(87)90030-8.

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Kurnio, Hananto, Subaktian Lubis et Hersenanto Catur Widi. « SUBMARINE VOLCANO CHARACTERISTICS IN SABANG WATERS ». BULLETIN OF THE MARINE GEOLOGY 30, n^o 2 (15 février 2016) : 85. http://dx.doi.org/10.32693/bomg.30.2.2015.78.

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The aim of the study is to understand the characteristics of a volcano occurred in marine environment, as Weh Island where Sabang City located is still demonstrated its volcanic cone morphology either through satellite imagery or bathymetric map. Methods used were marine geology, marine geophysics and oceanography. Results show that surface volcanism (sea depth less than 50 m) take place as fumaroles, solfataras, hot ground, hot spring, hot mud pool and alteration in the vicinities of seafloor and coastal area vents. Seismic records also showed acoustic turbidity in the sea water column due to gas bubblings produced by seafloor fumaroles. Geochemical analyses show that seafloor samples in the vicinities of active and non-active fumarole vent are abundances with rare earth elements (REE). These were interpreted that the fumarole bring along REE through its gases and deposited on the surrounding seafloor surface. Co-existence between active fault of Sumatra and current volcanism produce hydrothermal mineralization in fault zone as observed in Serui and Pria Laot-middle of Weh Island which both are controlled by normal faults and graben.Keywords: submarine volcano, hydrothermal mineralization, Sabang-Weh-Aceh. Tujuan kajian adalah memahami karakteristik suatu gunungapi yang berada dalam lingkungan marin, sebagaimana Pulau Weh dimana Kota Sabang terletak masih menunjukkan morfologi kerucut volkaniknya baik melalui citra satelit maupun batimetri. Metoda yang digunakan adalah geologi kelautan, geofisika kelautan dan oseanografi. Hasil menunjukkan bahwa volkanisma permukaan (kedalaman laut kurang dari 50 m) terdapat dalam bentuk fumarola, solfatara, lahan panas, mata air panas, kolam lumpur panas dan alterasi sekitar lobang kepundan dasar laut dan pantai. Rekaman seismik juga menunjukkan turbiditas akustik dalam kolom air laut akibat gelembung gas yang dihasilkan oleh fumarola dasar laut. Analisis geokimia menunjukkan bahwa contoh-contoh dasar laut sekitar lobang kepundan fumarola yang aktif maupun tidak aktif kaya akan logam tanah jarang. Ini ditafsirkan bahwa proses fumarola tersebut membawa REE melalui gas-gasnya dan mengendapkannya pada permukaan dasar laut di sekitar. Ko-eksistensi antara Sesar Sumatera aktif dan volkanisma Resen menghasilkan mineralisasi hidrotermal dalam zona sesar seperti teramati di Serui dan Pria Laot - bagian tengah Pulau Weh yang keduanya dikontrol oleh sesar normal dan graben. Kata kunci: gunungapi bawah laut, mineralisasi hidrotermal, Sabang-Weh-Aceh.

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Igarashi, George, Tetsuya Fujii, Toshiya Mori, Kenji Notsu et Sei-ichiro Watanabe. « Continuous monitoring of fumarolic gas flux at a bore hole in an active volcanic island ». Geophysical Research Letters 27, n^o 10 (15 mai 2000) : 1539–42. http://dx.doi.org/10.1029/1999gl008450.

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Mori, Toshiya, Kenji Notsu, Yasunori Tohjima, Hiroshi Wakita, P. Mario Nuccio et Francesco Italiano. « Remote detection of fumarolic gas chemistry at Vulcano, Italy, using an FT-IR spectral radiometer ». Earth and Planetary Science Letters 134, n^o 1-2 (août 1995) : 219–24. http://dx.doi.org/10.1016/0012-821x(95)00119-w.

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Garofalo, K., F. Tassi, O. Vaselli, A. Delgado-Huertas, D. Tedesco, M. Frische, T. H. Hansteen, R. J. Poreda et W. Strauch. « Fumarolic gases at Mombacho volcano (Nicaragua) : presence of magmatic gas species and implications for volcanic surveillance ». Bulletin of Volcanology 69, n^o 7 (12 janvier 2007) : 785–95. http://dx.doi.org/10.1007/s00445-006-0108-z.

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Notsu, Kenji, Hiroshi Wakita et George Igarashi. « Precursory changes in fumarolic gas temperature associated with a recent submarine eruption near Izu-Oshima Volcano, Japan ». Geophysical Research Letters 18, n^o 2 (février 1991) : 191–93. http://dx.doi.org/10.1029/91gl00211.

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D’Alessandro, W., L. Brusca, M. Martelli, A. Rizzo et K. Kyriakopoulos. « GEOCHEMICAL CHARACTERIZATION OF NATURAL GAS MANIFESTATIONS IN GREECE ». Bulletin of the Geological Society of Greece 43, n^o 5 (31 juillet 2017) : 2327. http://dx.doi.org/10.12681/bgsg.11633.

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The Greek region is characterized by intense geodynamic activity with widespread volcanic, geothermal and seismic activity. Its complex geology is reflected in the large variety of chemical and isotopic composition of its gas manifestations. Basing on their chemical composition the gases can be subdivided in three groups, respectively CO2, CH4 or N2-dominated. On oxygen-free basis these three gases make up more than 97% of the total composition. The only exceptions are fumarolic gases of Nisyros that contain substantial amounts of H2S (up to more than 20%) and one sample of Milos that contains 15% of H2. CO2-dominated gases with clear mantle contribution in their He isotopic composition (R/Ra corrected for air contamination ranging from 0.5 to 5.7) are found along the subduction-related south Aegean active volcanic arc and on the Greek mainland close to recent (upper Miocene to Pleistocene) volcanic centers. These areas are generally characterized by active or recent extensive tectonic activity and high geothermal gradients. On the contrary, gases sampled in the more external nappes of the Hellenide orogen have generally a CH4- or N2-rich compositions and helium isotope composition with a dominant crustal contribution (R/Ra corr < 0.2). The chemical and isotopic characteristics of the emitted gas display therefore a clear relationshipwith the different geodynamic sectors of the region. Gas geochemistry of the area contributes to a better definition of the crust-mantle setting of the Hellenic region.

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Sumino, Hirochika, Kenji Notsu, Shun'ichi Nakai, Masanori Sato, Keisuke Nagao, Morikazu Hosoe et Hiroshi Wakita. « Noble gas and carbon isotopes of fumarolic gas from Iwojima volcano, Izu–Ogasawara arc, Japan : implications for the origin of unusual arc magmatism ». Chemical Geology 209, n^o 1-2 (septembre 2004) : 153–73. http://dx.doi.org/10.1016/j.chemgeo.2004.05.002.

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Bani, Philipson, Etienne Le Glas, Kristianto Kristianto, Alessandro Aiuppa, Marcello Bitetto et Devy Kamil Syahbana. « Elevated CO2 Emissions during Magmatic-Hydrothermal Degassing at Awu Volcano, Sangihe Arc, Indonesia ». Geosciences 10, n^o 11 (20 novembre 2020) : 470. http://dx.doi.org/10.3390/geosciences10110470.

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Awu is a remote and little known active volcano of Indonesia located in the northern part of Molucca Sea. It is the northernmost active volcano of the Sangihe arc with 18 eruptions in less than 4 centuries, causing a cumulative death toll of 11,048. Two of these eruptions were classified with a Volcanic Explosivity Index (VEI) of 4. Since 2004, a lava dome has occupied the centre of Awu crater, channelling the fumarolic gas output along the crater wall. A combined Differential Optical Absorption Spectroscopy (DOAS) and Multi-component Gas Analyzer System (Multi-GAS) study highlight a relatively small SO2 flux (13 t/d) sustained by mixed magmatic–hydrothermal emissions made-up of 82 mol.% H2O, 15 mol.% CO2, 2.55 mol.% total S (ST) and 0.02 mol.% H2. The CO2 emission budget, as observed during a short observation period in 2015, corresponds to a daily contribution to the atmosphere of 2600 t/d, representing 1% of the global CO2 emission budget from volcanoes. The gas CO2/ST ratio of 3.7 to 7.9 is at the upper limit of the Indonesian gas range, which is ascribed to (i) some extent of S loss during hydrothermal processing, and perhaps (ii) a C-rich signature of the feeding magmatic gas phase. The source of this high CO2 signature and flux is yet to be fully understood; however, given the peculiar geodynamic context of the region, dominated by the arc-to-arc collision, this may result from either the prolonged heating of the slab and consequent production of carbon-rich fluids, or the recycling of crustal carbon.

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Fagorzi, Camilla, Sara Del Duca, Stefania Venturi, Carolina Chiellini, Giovanni Bacci, Renato Fani et Franco Tassi. « Bacterial Communities from Extreme Environments : Vulcano Island ». Diversity 11, n^o 8 (20 août 2019) : 140. http://dx.doi.org/10.3390/d11080140.

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Although volcanoes represent extreme environments for life, they harbour bacterial communities. Vulcano Island (Aeolian Islands, Sicily) presents an intense fumarolic activity and widespread soil degassing, fed by variable amounts of magmatic gases (dominant at La Fossa Crater) and hydrothermal fluids (dominant at Levante Bay). The aim of this study is to analyse the microbial communities from the different environments of Vulcano Island and to evaluate their possible correlation with the composition of the gas emissions. Microbial analyses were carried out on soils and pioneer plants from both La Fossa Crater and Levante Bay. Total DNA has been extracted from all the samples and sequenced through Illumina MiSeq platform. The analysis of microbiome composition and the gases sampled in the same sites could suggest a possible correlation between the two parameters. We can suggest that the ability of different bacterial genera/species to survive in the same area might be due to the selection of particular genetic traits allowing the survival of these microorganisms. On the other side, the finding that microbial communities inhabiting different sites exhibiting different emission profiles are similar might be explained on the basis of a possible sharing of metabolic abilities related to the gas composition.

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Fiebig, Jens, Giovanni Chiodini, Stefano Caliro, Andrea Rizzo, Jorge Spangenberg et Johannes C. Hunziker. « Chemical and isotopic equilibrium between CO2 and CH4 in fumarolic gas discharges : Generation of CH4 in arc magmatic-hydrothermal systems ». Geochimica et Cosmochimica Acta 68, n^o 10 (mai 2004) : 2321–34. http://dx.doi.org/10.1016/j.gca.2003.10.035.

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Shablinskii, Andrey P., Stanislav K. Filatov, Sergey V. Krivovichev, Lidiya P. Vergasova, Svetlana V. Moskaleva, Eugeniya Yu Avdontseva, Alexander V. Knyazev et Rimma S. Bubnova. « Dobrovolskyite, Na4Ca(SO4)3, a new fumarolic sulfate from the Great Tolbachik fissure eruption, Kamchatka Peninsula, Russia ». Mineralogical Magazine 85, n^o 2 (29 janvier 2021) : 233–41. http://dx.doi.org/10.1180/mgm.2021.9.

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AbstractDobrovolskyite, Na4Ca(SO4)3, is a new sulfate mineral from the Great Tolbachik fissure eruption, Kamchatka peninsula, Russia. It occurs as aggregates of tabular crystals up to 1–2 mm in maximum dimension, with abundant gas inclusions. The empirical formula calculated on the basis of O = 12 is (Na3.90K0.10)Σ4(Ca0.45Mg0.16Cu0.12Na0.10)Σ0.83S3.08O12. The crystal structure of dobrovolskyite was determined using single-crystal X-ray diffraction data as: trigonal, R3, a = 15.7223(2), c = 22.0160(5) Å, V = 4713.1(2) Å3, Z = 18 and R1 = 0.072. The Mohs’ hardness is 3.5. The mineral is uniaxial (+), with ω = 1.489(2) and ɛ = 1.491(2) (λ = 589 nm). The seven strongest lines of the powder X-ray diffraction pattern [d, Å (I, %)(hkl)] are: 11.58(40)(101); 5.79(22)(202); 4.54(18)(030); 3.86(88)(033); 3.67(32)(006); 2.855(50)(306); and 2.682(100)(330). The mineral is named in honour of Prof. Dr. Vladimir Vitalievich Dolivo-Dobrovolsky (1927–2009), one of the leading Russian scientists in the field of petrology, crystal optics and crystal chemistry. The crystal structure of dobrovolskyite can be described as composed of three symmetrically independent rods running parallel to the c axis. The rods consist of six octahedral–tetrahedral [Na(SO4)6]11– or [Ca(SO4)6]10– clusters of central octahedra sharing common corners with six adjacent SO4 tetrahedra. Alternatively, the crystal structure of the mineral can be described as a 12-layer ABACABACABAC eutactic array of Na+ and Ca2+ cations, and vacancies with disordered (SO4) tetrahedra in interstices. Dobrovolskyite and similar minerals probably formed upon cooling of a high-temperature phase with disordered cation and anion arrangements.

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Nuzhdaev, I. A., A. Yu Ozerov, A. A. Nuzhdaev et D. V. Melnikov. « THE FUMAROLE «LEDOVAYA» OF ICHINSKY VOLCANO (KAMCHATKA) IN 2020 ». Bulletin of Kamchatka Regional Association «Educational-Scientific Center». Earth Sciences, n^o 4(52) (2021) : 108–12. http://dx.doi.org/10.31431/1816-5524-2021-4-52-108-112.

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Ichinsky volcano is the largest volcanic structure of the Sredinny Range of Kamchatka. The manifestation of fumarole activity on the northern slope of the volcano is known since 1956. 64 years after the discovery of the Ledovaya fumarole, it was inspected with a quadrocopter. It was found that the fumarole is located at an altitude of 2725 m and is a large funnel up to 60 m in size, covered with snow in the middle part. In the upper part of the funnel there is a hole in the ice mass 9.8 m in diameter, with vapor-gas clouds rising up to 5–10 m above its edge.. The walls of the ice well are covered with a grayish-yellow fouling of sublimations. The authors believe that the probable temperature of the vapor-gas mixture of fumaroles at the outlet of the volcano rocks is significantly higher than 100° C.

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Gliß, Jonas, Kerstin Stebel, Arve Kylling et Aasmund Sudbø. « Improved optical flow velocity analysis in SO<sub>2</sub> ; camera images of volcanic plumes – implications for emission-rate retrievals investigated at Mt Etna, Italy and Guallatiri, Chile ». Atmospheric Measurement Techniques 11, n^o 2 (8 février 2018) : 781–801. http://dx.doi.org/10.5194/amt-11-781-2018.

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Abstract. Accurate gas velocity measurements in emission plumes are highly desirable for various atmospheric remote sensing applications. The imaging technique of UV SO2 cameras is commonly used to monitor SO2 emissions from volcanoes and anthropogenic sources (e.g. power plants, ships). The camera systems capture the emission plumes at high spatial and temporal resolution. This allows the gas velocities in the plume to be retrieved directly from the images. The latter can be measured at a pixel level using optical flow (OF) algorithms. This is particularly advantageous under turbulent plume conditions. However, OF algorithms intrinsically rely on contrast in the images and often fail to detect motion in low-contrast image areas. We present a new method to identify ill-constrained OF motion vectors and replace them using the local average velocity vector. The latter is derived based on histograms of the retrieved OF motion fields. The new method is applied to two example data sets recorded at Mt Etna (Italy) and Guallatiri (Chile). We show that in many cases, the uncorrected OF yields significantly underestimated SO2 emission rates. We further show that our proposed correction can account for this and that it significantly improves the reliability of optical-flow-based gas velocity retrievals. In the case of Mt Etna, the SO2 emissions of the north-eastern crater are investigated. The corrected SO2 emission rates range between 4.8 and 10.7 kg s−1 (average of 7.1 ± 1.3 kg s−1) and are in good agreement with previously reported values. For the Guallatiri data, the emissions of the central crater and a fumarolic field are investigated. The retrieved SO2 emission rates are between 0.5 and 2.9 kg s−1 (average of 1.3 ± 0.5 kg s−1) and provide the first report of SO2 emissions from this remotely located and inaccessible volcano.

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Aiuppa, A., G. Tamburello, R. Di Napoli, C. Cardellini, G. Chiodini, G. Giudice, F. Grassa et M. Pedone. « First observations of the fumarolic gas output from a restless caldera : Implications for the current period of unrest (2005-2013) at Campi Flegrei ». Geochemistry, Geophysics, Geosystems 14, n^o 10 (octobre 2013) : 4153–69. http://dx.doi.org/10.1002/ggge.20261.

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Madonia, Paolo, Marianna Cangemi, Marcello Colajanni et Aldo Winkler. « Atmospheric Concentration of CO2 and PM2.5 at Salina, Stromboli, and Vulcano Islands (Italy) : How Anthropogenic Sources, Ordinary Volcanic Activity and Unrests Affect Air Quality ». International Journal of Environmental Research and Public Health 19, n^o 8 (15 avril 2022) : 4833. http://dx.doi.org/10.3390/ijerph19084833.

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Geogenic and anthropogenic sources of atmospheric particulate and CO2 can lead to threats to human health in volcanic areas. Although the volcanic CO2 hazard is a topic frequently debated in the related scientific literature, space and time distribution of PM2.5 are poorly known. The results of combined CO2/PM2.5 surveys, carried out at Salina, Stromboli, and Vulcano islands (Aeolian archipelago, Italy) in the years 2020–2021, and integrated with investigations on bioaccumulation of metallic particulate matter by the mean of data on the magnetic properties of oleander leaves, are presented in this work. The retrieved results indicate that no significant anthropogenic sources for both CO2 and PM2.5 are active in these islands, at the net of a minor contribution due to vehicular traffic. Conversely, increments in volcanic activity, as the unrest experienced by Vulcano island since the second half of 2021, pose serious threats to human health, due to the near-ground accumulation of CO2, and the presence of suspended micro-droplets of condensed hydrothermal vapor, fostering the diffusion of atmophile viruses, such as the COVID-19. Gas hazard conditions can be generated, not only by volcanic vents or fumarolic fields, but also by unconventional sources, such as the outgassing from shallow hydrothermal aquifers through drilled or hand-carved wells.

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Vatserionova, E. O., A. V. Kopanina et I. I. Vlasova. « Bark of assimilation shoots of the Beauverd spirea shrub (Spiraea beauverdiana S.K. Schneid.) : structural changes under the conditions of volcanic stress in the South Kuril Islands and the Kamchatka Peninsula ». Geosystems of Transition Zones 6, n^o 4 (2022) : 339–59. http://dx.doi.org/10.30730/gtrz.2022.6.4.339-359.

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The article analyzes the bark of annual assimilation shoots of the Beauverd spirea shrub (Spiraea beauverdiana S.K. Schneid., Rosaceae Juss.) growing under the stressful conditions of volcanic and post-volcanic activity in the Kuril Islands (Kunashir, Iturup) and the Kamchatka Peninsula. The combination of negative environmental factors under the conditions of fumarolic, gas-hydrothermal activity and on pyroclastic deposits in volcanogenic landscapes causes disturbance in the activity of the lateral meristems of the stem – phellogen and vascular cambium. Under the conditions of volcanic stress, the functional activity of these meristems can be both constant and intermittent during the growing season, or may be completely absent (temporary dormancy of meristems). As a result of combinations of different functional activity of meristems in assimilation shoots and in their individual sections, different anatomical structures of the cortex can form in S. beauverdiana. Based on the totality of structural and functional features, we identified three types of anatomical organization of the one-year-old cortex in S. beauverdiana from volcanic habitats, which are visualized by light microscopy in the form of contrasting anatomical patterns. We believe the structural changes in the one-year-old crust formed as a result of the unstable activity of the phellogen and vascular cambium under the influence of volcanic stress, to be adaptive.

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Pekov, Igor V., Natalia V. Zubkova, Dmitry I. Belakovskiy, Vasiliy O. Yapaskurt, Marina F. Vigasina, Inna S. Lykova, Evgeny G. Sidorov et Dmitry Yu Pushcharovsky. « Chrysothallite K6Cu6Tl3+Cl17(OH)4·H2O, a new mineral species from the Tolbachik volcano, Kamchatka, Russia ». Mineralogical Magazine 79, n^o 2 (avril 2015) : 365–76. http://dx.doi.org/10.1180/minmag.2015.079.2.14.

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AbstractA new mineral chrysothallite K6Cu6Tl3+Cl17(OH)4·H2O was found in two active fumaroles, Glavnaya Tenoritovaya and Pyatno, at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. Chrysothallite seems to be a product of the interactions involving high-temperature sublimate minerals, fumarolic gas and atmospheric water vapour at temperatures not higher than 150ºC. It is associated with belloite, avdoninite, chlorothionite, sanguite, eriochalcite, mitscherlichite, sylvite, carnallite and kainite at Glavnaya Tenoritovaya and with belloite, avdoninite, chlorothionite, eriochalcite, atacamite, halite, kröhnkite, natrochalcite, gypsum and antlerite at Pyatno. The mineral forms equant-to-thick tabular crystals up to 0.05 mm, typically combined in clusters or crusts up to 1 mm across. Crystal forms are: {001}, {100}, {110}, {101} and {102}. Chrysothallite is transparent, bright golden-yellow to light yellow in finely crystalline aggregates. The lustre is vitreous. The mineral is brittle. Cleavage was not observed, the fracture is uneven. Dmeas = 2.95(2), Dcalc = 2.97 g cm–3. Chrysothallite is optically uniaxial (+), ω = 1.720(5), ε = 1.732(5). The Raman spectrum is given. The chemical composition (wt.%, electron-microprobe data, H2O calculated based on the crystal structure data) is: K 15.92, Cu 24.56, Zn 1.38, Tl 13.28, Cl 40.32, H2O(calc.) 3.49, total 98.95. The empirical formula, calculated on the basis of 17 Cl + 5 O a.p.f.u., is: K6.09(Cu5.78Zn0.32)Σ6.10Tl0.97Cl17[(OH)3.80O0.20]·H2O. Chrysothallite is tetragonal, I4/mmm, a = 11.3689(7), c = 26.207(2) Å, V = 3387.3(4) Å3, Z = 4. The strongest reflections of the powder X-ray pattern [d, Å (I)(hkl)] are: 13.20(44)(002); 6.88(100)(112); 5.16(30)(202, 114); 4.027(25)(220); 3.471(28)(206), 3.153(30)(314), 3.075(47)(305), 2.771(38)(316). The crystal structure (solved from single-crystal X-ray diffraction data, R = 0.0898) is unique. Its basic structural unit is a (001) layer of edge-sharing distorted CuCl4(OH)2 octahedra. Two Tl3+ cations occupy the centre of isolated TlCl6 and TlCl4(H2O)2 octahedra connected to each other and to the Cu polyhedral layers via KCl6 and KCl9 polyhedra. The name reflects the bright golden-yellow colour of the mineral (from the Greek χρυσος, gold) and the presence of thallium. Chrysothallite is the second known mineral with species-defining trivalent thallium.

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Saito, Genji, Hiroshi Shinohara et Kohei Kazahaya. « Successive sampling of fumarolic gases at Satsuma-Iwojima and Kuju volcanoes, southwest Japan : Evaluation of short-term variations and precision of the gas sampling and analytical techniques. » GEOCHEMICAL JOURNAL 36, n^o 1 (2002) : 1–20. http://dx.doi.org/10.2343/geochemj.36.1.

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Pautov, Leonid A., Mirak A. Mirakov, Oleg I. Siidra, Abdulkhak R. Faiziev, Еvgeny V. Nazarchuk, Vladimir Yu Karpenko et Saimudasir Makhmadsharif. « Falgarite, K4(VO)3(SO4)5, a new mineral from sublimates of a natural underground coal fire at the tract of Kukhi-Malik, Fan-Yagnob coal deposit, Tajikistan ». Mineralogical Magazine 84, n^o 3 (1 avril 2020) : 455–62. http://dx.doi.org/10.1180/mgm.2020.22.

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AbstractA new mineral falgarite, K4(V+4O)3(SO4)5 was discovered at the tract of Kukhi-Malik, Fan-Yagnob coal deposit, ca. 75 km N of Dushanbe, Tajikistan. The new mineral is named after the Falgar, an ancient Sogdian name for an area around the Zeravshan riverhead. Falgarite is a fumarolic mineral formed directly from a gas emitted by a natural underground coal fire. Associated minerals are anhydrite, baryte, molybdite, an unidentified Tl-vanadyl sulfate, K–Mg sulfate and an anhydrous Mg-sulfate. Falgarite forms small isometric or pseudo-octahedral individual crystals (10–60 μm) of turquoise colour and spherical aggregates up to 0.5 mm in diameter. Mohs hardness is ~ 2.5, Dmeas = 2.87(2) and Dcalc = 2.89 g/cm3. Refractive indices are: α = 1.588(3), β(calc.) = 1.600(3) and γ = 1.609(2) (590 nm). In transmitted light falgarite is transparent green with a weak pleochroism. The mineral is non-soluble in H2O and 5% HNO3 at room temperature. Infrared spectra support the absence of H2O and OH–. The chemical composition determined by electron-microprobe analysis is (wt.%): Na2O 0.55, K2O 20.76, Tl2O 1.83, VO2 29.38 and SO3 46.78, total 99.29. The empirical formula (based on 23 O apfu) is: (K3.76Na0.15Tl0.07)Σ3.98V3.02S4.99O23.0. The strongest lines of the powder X-ray diffraction pattern are [d,Å(I,%)(hkl)]: 3.20(70)(202); 3.17(80)024; 3.14(70)$\bar{2}$04; 3.01(50)$\bar{1}$51; and 2.88(100)151. Falgarite is monoclinic, P21/n, a = 8.7209(5), b = 16.1777(6), c = 14.4614(7) Å, β = 106.744(5)°, V = 1953.77(17) Å3, Z = 4 and R1 = 0.05. VO6 octahedra and SO4 tetrahedra link together by sharing corners thus forming a [(VO)3(SO4)5]4– framework. K+, Na+ and Tl+ cations are located in the channels of the framework. The synthetic K4(VO)3(SO4)5 analogue is known.

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Ostrooumov, M., et Y. Taran. « Vanadium, V – a new native element mineral from the Colima volcano, State of Colima, Mexico, and implications for fumarole gas composition ». Mineralogical Magazine 80, n^o 2 (avril 2016) : 371–82. http://dx.doi.org/10.1180/minmag.2016.080.006.

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AbstractVanadium, V, is a new mineral found in sublimates of high-temperature fumaroles of the Colima volcano, Mexico. The mineral precipitates over a narrow temperature range of 550–680°C, and occurs in association with colimaite (K3VS4) and shcherbinaite (V2O5). Native vanadium was been found on the inner wall of an inserted silica tube and subsequently in the adjacent rock of the Z3 fumarole. Vanadium forms smooth, irregular to flattened crystals, 5–20 μm in diameter. Smaller irregular crystals have also been observed in silica tubes. Due to its small crystal size, its physical properties (hardness, cleavage and density) could not be determined. An EDS spectrum indicated the presence of V, Fe, Al and Ti with an empirical formula calculated on the basis of EPMA analyses of V0.86Fe0.09Al0.04Ti0.01. Gandolfi and glancing-angle X-ray diffraction data showed that the microcrystals were body-centred cubic, space group Im3̄m, a = 3.022(3) Å, V = 27.60 (5) Å3, Z = 2. The five strongest calculated diffraction lines are [ d spacings in Å, (I) (hkl)]: 2.1411 (100)(110), 1.5126 (12)(200), 1.2301 (19)(211), 0.9565 (8)(310) and 8.8090 (11)(321). The calculated density is 6.033 g cm–3. Thermochemical modelling was used to explain why very oxidized gas at Colima precipitates V-bearing minerals and some native elements (vanadium and gold). Vanadium, is the second newly recognized mineral species (after colimaite) collected from an active fumarole in this volcanic crater. The mineral and its name have been approved by the CNMNC (IMA 2012-021a).

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Kanellopoulos, C., et N. Xirokostas. « MUDPOTS AT STEFANOS HYDROTHERMAL CRATER OF NISYROS VOLCANO. AN INSIGHT AT THE HYDROTHERMAL PROCESSES OF AN ACTIVE VOLCANO ». Bulletin of the Geological Society of Greece 50, n^o 4 (28 juillet 2017) : 1838. http://dx.doi.org/10.12681/bgsg.14112.

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On Nisyros island as a result of the volcanic activity and active tectonic, a hydrothermal system develops and it is expressed by 5 types of surface manifestations: i) thermal springs, ii) fumaroles iii) hydrothermal craters, iv) hot grounds and v) mudpots. In general, a mudpot could be described as an acidic hot spring and fumarole with limited water which it is formed in high temperature geothermal areas. Water sample and depositions of mudpots collected, analyzed and studied from Stefanos hydrothermal crater, which is the only site on Nisyros Island, where mudpots occur. Mudpots water is very acidic (pH=2.4), with high sulfate concentration (1375mg/L), due to the H2S(gas) and temperature near the boiling point. As a result, elemental sulfur is found inside the depositions alongside with products of the hydrothermal alteration of the surrounding rocks. In the water and in the depositions were found high concentrations in several elements (e.g. in water: 55mg/L Fe; 19.5mg/L Zn, in depositions: 430mg/Kg Pb; 72mg/Kg Cu; 60mg/Kg Cr) reflecting the alterations processes which are taking place.

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Pekov, Igor V., Natalia V. Zubkova, Andrey A. Zolotarev, Vasiliy O. Yapaskurt, Sergey V. Krivovichev, Dmitry I. Belakovskiy, Inna Lykova et al. « Dioskouriite, CaCu4Cl6(OH)4∙4H2O : A New Mineral Description, Crystal Chemistry and Polytypism ». Minerals 11, n^o 1 (18 janvier 2021) : 90. http://dx.doi.org/10.3390/min11010090.

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A new mineral, dioskouriite, CaCu4Cl6(OH)4∙4H2O, represented by two polytypes, monoclinic (2M) and orthorhombic (2O), which occur together, was found in moderately hot zones of two active fumaroles, Glavnaya Tenoritovaya and Arsenatnaya, at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. Dioskouriite seems to be a product of the interactions involving high-temperature sublimate minerals, fumarolic gas and atmospheric water vapor at temperatures not higher than 150 °C. It is associated with avdoninite, belloite, chlorothionite, eriochalcite, sylvite, halite, carnallite, mitscherlichite, chrysothallite, sanguite, romanorlovite, feodosiyite, mellizinkalite, flinteite, kainite, gypsum, sellaite and earlier hematite, tenorite and chalcocyanite in Glavnaya Tenoritovaya and with avdoninite and earlier hematite, tenorite, fluorophlogopite, diopside, clinoenstatite, sanidine, halite, aphthitalite-group sulfates, anhydrite, pseudobrookite, powellite and baryte in Arsenatnaya. Dioskouriite forms tabular, lamellar or flattened prismatic, typically sword-like crystals up to 0.01 mm × 0.04 mm × 0.1 mm combined in groups or crusts up to 1 × 2 mm2 in area. The mineral is transparent, bright green with vitreous luster. It is brittle; cleavage is distinct. The Mohs hardness is ca. 3. Dmeas is 2.75(1) and Dcalc is 2.765 for dioskouriite-2O and 2.820 g cm−3 for dioskouriite-2M. Dioskouriite-2O is optically biaxial (+), α = 1.695(4), β = 1.715(8), γ = 1.750(6) and 2Vmeas. = 70(10)°. The Raman spectrum is reported. The chemical composition (wt%, electron microprobe data, H2O calculated by total difference; dioskouriite-2O/dioskouriite-2M) is: K2O 0.03/0.21; MgO 0.08/0.47; CaO 8.99/8.60; CuO 49.24/49.06; Cl 32.53/32.66; H2O(calc.) 16.48/16.38; -O=Cl −7.35/−7.38; total 100/100. The empirical formulae based on 14 O + Cl apfu are: dioskouriite-2O: Ca1.04(Cu4.02Mg0.01)Σ4.03[Cl5.96(OH)3.90O0.14]Σ10∙4H2O; dioskouriite-2M: (Ca1.00K0.03)Σ4.03(Cu4.01Mg0.08)Σ4.09[Cl5.99(OH)3.83O0.18]Σ10∙4H2O. Dioskouriite-2M has the space group P21/c, a = 7.2792(8), b = 10.3000(7), c = 20.758(2) Å, β = 100.238(11)°, V = 1531.6(2) Å3 and Z = 4; dioskouriite-2O: P212121, a = 7.3193(7), b = 10.3710(10), c = 20.560(3) Å, V = 1560.6(3) Å3 and Z = 4. The crystal structure (solved from single-crystal XRD data, R = 0.104 and 0.081 for dioskouriite-2M and -2O, respectively) is unique. The structures of both polytypes are based upon identical BAB layers parallel to (001) and composed from Cu2+-centered polyhedra. The core of each layer is formed by a sheet A of edge-sharing mixed-ligand octahedra centered by Cu(1), Cu(2), Cu(3), Cu(5) and Cu(6) atoms, whereas distorted Cu(4)(OH)2Cl3 tetragonal pyramids are attached to the A sheet on both sides, along with the Ca(OH)2(H2O)4Cl2 eight-cornered polyhedra, which provide the linkage of the two adjacent layers via long Ca−Cl bonds. The Cu(4) and Ca polyhedra form the B sheet. The difference between the 2M and 2O polytypes arises as a result of different stacking of layers along the c axis. The cation array of the layer corresponds to the capped kagomé lattice that is also observed in several other natural Cu hydroxychlorides: atacamite, clinoatacamite, bobkingite and avdoninite. The mineral is named after Dioskouri, the famous inseparable twin brothers of ancient Greek mythology, Castor and Polydeuces, the same in face but different in exercises and achievements; the name is given in allusion to the existence of two polytypes that are indistinguishable in appearance but different in symmetry, unit cell configuration and XRD pattern.

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Prasetio, Rasi, Neneng Laksminingpuri et Evarista Ristin Pujiindiyati. « Konsentrasi Radon-222 dalam Gas Tanah untuk Deteksi Distribusi Permeabilitas di Daerah Panas Bumi Tampomas, Jawa Barat ». EKSPLORIUM 41, n^o 1 (30 mai 2020) : 53. http://dx.doi.org/10.17146/eksplorium.2020.41.1.5642.

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ABSTRAK Daerah upflow dalam sistem panas bumi merupakan daerah dengan permeabilitas yang tinggi sebagai lintasan naiknya fluida panas bumi ke permukaan, yang umumnya ditandai dengan adanya fumarol di permukaan. Gunung Tampomas, Jawa Barat, merupakan salah satu lokasi potensi panas bumi yang memiliki manifestasi berupa mata air panas, namun tidak memiliki fumarol atau steam vent. Zona permeabel atau upflow sulit untuk diidentifikasi. Isotop 222Rn merupakan isotop geogenik yang konsentrasinya di dalam gas tanah dapat menunjukkan permeabilitas, baik permeabilitas primer maupun sekunder (struktur). Serangkaian pengukuran 222Rn dalam gas tanah telah dilakukan pada 56 titik di sekitar Gunung Tampomas untuk melihat anomali kandungan 222Rn dengan menggunakan metode statistik, serta relasinya antara daerah dengan permeabilitas tinggi dengan struktur geologi dan manifestasi panas bumi. Hasil pengukuran dan evaluasi statistik menunjukkan bahwa konsentrasi 222Rn terbagi menjadi konsentrasi rendah (latar), konsentrasi tinggi, dan anomali. Nilai latar berada di 16 lokasi berada di bawah 825 Bq/m3, sementara konsentrasi tinggi di 32 lokasi antara 825–7688 Bq/m3 dan anomali di 8 lokasi di atas 7688 Bq/m3. Sebagian besar lokasi dengan konsentrasi 222Rn tinggi dan anomali letaknya tidak berdekatan dengan kelurusan struktur, Seluruh pengukuran yang berdekatan dengan mata air panas memiliki konsentrasi 222Rn tinggi dan anomali. Mata air panas Ciseupan merupakan pengecualian yang mengindikasikan air panas tersebut keluar secara lateral (outflow). Selain itu, tidak ada indikasi korelasi antara konsentrasi 222Rn dengan elevasi lokasi pengukuran. Proses perpindahan 222Rn dari reservoir ke permukaan diperkirakan melalui mekanisme gas pembawa yang berasal dari reservoir panas bumi melalui zona permeabel.ABSTRACT Upflow zone in the geothermal system is a zone with high permeability that serves as a path for geothermal fluid to ascend to the surface, which usually marked with fumarole at the surface. Mount Tampomas, West Java, is a potential geothermal site with some thermal manifestation in the form of hot springs, but no fumarole or steam vent exists. The up-flow or the permeable zone is difficult to identify. 222Rn isotope is a radiogenic isotope that its concentration in soil gas can infer primary permeability as well as secondary permeability (structure). Series of 222Rn measurement in soil gas has been performed from 56 sampling positions around Mount Tampomas to evaluate 222Rn anomaly by a statistical method and its relation with high permeability area, geological structure, and geothermal manifestation. The measurement and statistical evaluation results show that 222Rn concentration clustered into low (background), high, and anomaly concentration. The background values in 16 places are below 825 Bq/m3, while a high level in 32 areas between 825–7688 Bq/m3 and anomaly in 8 places above 7688 Bq/m3. Most of the locations with high and anomaly 222Rn concentrations did not locate near a structure lineament. All measurements near hot springs have a high 222Rn and anomaly. Ciseupan hot spring is an exception which may indicate that the hot spring is discharged laterally (outflow). Furthermore, there is no indication of a correlation between 222Rn with the elevation of the measurement location. The process of 222Rn transfer from the reservoir to the surface is considered by the geothermal reservoir's gas carrier mechanism through permeable zones.

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Kurnio, Hananto, Ildrem Syafri, Adjat Sudradjat, Mega Fatimah Rosana et Dicky Muslim. « SEAFLOOR FAULTING AND ITS RELATION TO SUBMARINE VOLCANIC ACTIVITIES BASED ON SUB BOTTOM PROFILING (SBP) ANALYSES IN WEH ISLAND WATERS AND ITS SURROUNDING, NANGROE ACEH DARUSSALAM PROVINCE ». BULLETIN OF THE MARINE GEOLOGY 30, n^o 1 (15 février 2016) : 1. http://dx.doi.org/10.32693/bomg.30.1.2015.70.

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Sub bottom Profiling survey using strata box, a specially designed low penetration sub bottom Profiling (< 80 m) for coastal waters exploration, found out evidence of submarine volcanic activities in northern coastal waters of Weh Island, NanggroeAceh Darussalam Province. Gas bubbling could be observed at water columns of the digital sub bottom Profiling records as acoustic turbidity. There are at least 33 spots of volcanic gas bursts observed from the sub bottom Profiling. Examination of gas bursts at coastal area which show fumaroles and solfatara indicate reduce volcanic activity either at submarine or terrestrial. Identification of seafloor gas burst by diving team found out that center of such burst is occurred at a north - south opened lineation assumed as normal fault. It seems that the seafloor normal fault is the continuation of terrestrial fault of the same direction as observed from terrain earth google of Weh Island.Keywords: seafloor faulting, submarine volcanic activities, shallow sub bottom Profiling data, Weh Island Aceh Survei penampang bawah dasar laut (SBP) menggunakan strata box, suatu alat SBP penetrasi rendah yang didisain untuk eksplorasi perairan pantai, mendapatkan bukti-bukti aktivitas gunungapi bawah laut di perairan sebelah utara Pulau Weh, Provinsi Nanggroe Aceh Darussalam. Gelembung-gelembung gas dapat diamati pada kolom air rekaman digital penampang bawah dasar laut sebagai turbiditas akustik. Sedikitnya dijumpai 33 titik semburan gas volkanik yang teramati dari penampang bawah dasar laut tersebut. Pemeriksaan semburan-semburan gas pada wilayah pantai sebagai fumarola dan solfataramenunjukkan telah berkurangnya aktivitas volkanik apakah pada dasar laut maupun darat. Identifikasi semburan gas dasar laut oleh tim selam mendapatkan bahwa pusat semburan berada pada kelurusan berarah utara - selatan yang diduga sebagai sesar normal. Tampaknya adalah bahwa sesar normal dasar laut tersebut merupakan kelanjutan sesar darat yang berorientasi sama seperti teramati dari citra earthgoogle terrain Pulau Weh. Kata kunci: pensesaran dasar laut, aktivitas gunungapi bawah laut, data penampang bawah dasar laut, Pulau Weh Aceh

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Feron, Romain, Pascal Bernard, Mathieu Feuilloy, Philippe Ménard, Alexandre Nercessian, Sébastien Deroussi, Thierry Kitou et Guy Plantier. « First Optical Seismometer at the Top of La Soufrière Volcano, Guadeloupe ». Seismological Research Letters 91, n^o 5 (5 août 2020) : 2448–57. http://dx.doi.org/10.1785/0220200126.

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Abstract Accurate monitoring of volcanic activity demands expertise in fields including geophysics, geology, and geochemistry. Data obtained from the most recent technical advances are particularly vital in pre-eruptive phases. In particular, seismic monitoring in near real time is essential to locating and discriminating early signs among different sources of seismic waves, especially those related to movement and overpressure in underground fluids. Among the major indicators of volcanic restlessness are fumaroles, or gas and steam vents, often located near a volcanic summit. Their activity could be monitored by seismometers in their vicinity, but today’s standard instruments cannot last very long when exposed to the high temperatures and the billowing, sulfurous, acidic gases near a fumarole. Conventional gear may also not be accessible for emergency deployment, or repair, even in pre-eruptive phases. La Soufrière de Guadeloupe Volcano in the Caribbean typifies such challenges. Its last significant event was a phreatic (gas and steam) eruption in 1976 that prompted evacuation of the archipelago’s nearby capital. Since early 2018, the 1467-meter-high stratovolcano has shown signs of increased activity. To provide a hardy, high-resolution monitoring system, we installed a recently developed type of seismometer just 10 m from a vigorous summit fumarole. The sensor is a purely opto-mechanical geophone that is interrogated through a 1.5 km fiber-optic cable by a remote, and thus it is a much safer optic-electronic system down the volcano’s flank. The ESEO Group and the Institut de Physique du Globe de Paris (IPGP) started development of this novel seismometer in 2008. The 2019 Guadeloupe installation is part of the HIgh PERformance SeISmometer (HIPERSIS) project (French Agence Nationale de la Recherche [ANR]). It is, to our knowledge, the first high-resolution optical seismometer ever installed on an active volcano or other active, hazardous zone. We report here the details of this installation, the means we are using for measurements, and our implementation strategy, and we share some of the first results. Such an optical seismometer, as well as a variety of other geophysical sensors built on the same principle, can be installed in a wide variety of sites with fibers up to 50 km long.

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Zhitova, Elena S., Dmitry A. Khanin, Anton A. Nuzhdaev, Maria A. Nazarova, Rezeda M. Ismagilova, Vladimir V. Shilovskikh, Anastasia N. Kupchinenko, Ruslan A. Kuznetsov et Pavel S. Zhegunov. « Efflorescent Sulphates with M+ and M2+ Cations from Fumarole and Active Geothermal Fields of Mutnovsky Volcano (Kamchatka, Russia) ». Minerals 12, n^o 5 (10 mai 2022) : 600. http://dx.doi.org/10.3390/min12050600.

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In this study, sulphate efflorescent minerals covering the surface of the Donnoe and Dachnoe fields of the Mutnovsky volcano are described. The minerals were precipitated on the argillic facies as the result of water–rock interaction and fumarole emission. A chemical composition of Ca, Ba, (NH4)+, Na-Fe3+, (NH4)+-Al, (NH4)+-Fe3+, Na-Al, K-Al, and K-Fe3+ sulphates was reported. Elements such as Sr, Mg, Co, Ni, Ti and P were found as isomorphic impurities. Ammonia species were concentrated around fumaroles. The mineral assemblage described herein is unique in relation to other geological settings and reflects the process of low-temperature mineral formation associated with volcanism. The thermal water contains cations such as H, Na, K, NH4, Ca, Mg, Fe2+, Fe3+, and Al in different proportions with pH ranging from 2.4 to 6.5 and the dominance of acidic waters. The gas condensate bears such cations as (NH4)+, Ca, and Mg and has a pH of ~5. Thus, the rest of the main cations are derived from the leaching of the host rocks. Among the identified phases, the alunite-supergroup minerals are more prone to isomorphism. The Ti, Co, and Ni impurities mark the unique geochemistry of thermal water at the Mutnovsky volcano. We postulate that the chemical composition of alunite-supergroup minerals reflects the types of hydrothermal occurrences and contains important information on the geochemistry of the hydrothermal process.

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TSUJIHARA, Makihiko, et Satomi IMAMURA. « ACTUAL USE OF FUMAROLE GAS FIXTURES ON KYUSHU ISLAND ». AIJ Journal of Technology and Design 19, n^o 41 (2013) : 255–60. http://dx.doi.org/10.3130/aijt.19.255.

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Eliyani, Eliyani, Muhammad Isa, Khairi Khairi et Muhammad Rusdi. « Reservoir Temperature Estimation By Using Geothermometry (Case Study on Geothermal Field Jaboi, Sabang) ». Journal of Aceh Physics Society 8, n^o 1 (30 janvier 2019) : 30–34. http://dx.doi.org/10.24815/jacps.v8i1.12992.

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Gunung api Leumo Matee dan Seumeuregoh, Jaboi Sabang memiliki potensi energi panas bumi sangat besar. Hal ini ditandai dengan adanya manifestasi yang muncul di permukaan seperti uap panas, fumarol dan sumber air panas. Oleh karena itu, perlu dikaji lebih dalam dan menyeluruh untuk mendapatkan informasi yang detail, terutama parameter suhu dan karakteristik batuan/mineral. Sebuah penelitian telah dilakukan untuk kajian geokimia terutama analisis kimia fluida panas bumi. Pendekatan untuk menentukan karakteristik fluida kimia panas bumi dilakukan dengan metode geotermometer untuk mengukur kandungan air (SiO2) dan gas (Na-K) serta konsentrasi anion dan kation. Berdasarkan data pengamatan lapangan dan hasil uji laboratorium yang sudah terstandarisasi menunjukkan bahwa suhu bawah permukaan untuk fluida cair adalah 228oC dan untuk gas sebesar 220oC. Hasil pengujian sampel fluida panas bumi menunjukkan bahwa manifestasi panas bumi Kawah I dan Kawah IV daerah Jaboi, Sabang sangat prospek untuk dikembangkan. Informasi fluida ini menjadi salah satu parameter dalam pengembangan potensi panas bumi. Oleh karena itu sangat penting ditindaklanjuti karena dapat menjawab kebutuhan energi yang ramah lingkungan dan energi terbarukan. The Volcano Leumo Matee and Seumeuregoh, Jaboi Sabang have enormous geothermal energy potential. This is characterized by the presence of surface manifestations such as hot steam, fumaroles and hot springs. Therefore, it needs to be studied more deeply and thoroughly to obtain detailed information, especially the temperature and rock/mineral characteristics. A study has been carried out for geochemical studies, especially chemical analysis of geothermal fluids. The approach to determine the characteristics of the geothermal chemical fluid is carried out by geothermometry to measure the water content (SiO2) and gas (Na-K) as well as the concentration of anions and cations. Based on field observations and standardized laboratory tests, the subsurface temperature for liquid fluids is 228oC and for gases of 220oC. The results of testing geothermal fluid samples show that the geothermal manifestations of Kawah I and Kawah IV Jaboi, Sabang are very prospects to be developed. This fluid information is one of the parameters in developing geothermal potential. Therefore, it is very important to follow up because it can answer the needs of environmentally friendly energy and renewable energy. Keywords: Volcano, Geothrmometry, jaboi, Sabang, Temperature

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Martadiastuti, Vanadia, Agung Harijoko, I. Wayan Warmada et Kotaro Yonezu. « Hydrogeochemical Characterization of GeothermalWater in Arjuno-Welirang, East Java, Indonesia ». Journal of Applied Geology 2, n^o 2 (23 octobre 2018) : 48. http://dx.doi.org/10.22146/jag.39979.

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Arjuno-Welirang Volcanic Complex (AWVC) is one of geothermal fields whichlocated in East Java province, Indonesia. It belongs to a Quarternary volcanic arc and has potential for development of electricity. The field is situated in a steep volcanic terrain and there are only few geothermal manifestations, i.e., hot springs, fumaroles, solfataras, steaming ground and hydrothermal alteration. This study aims to classify the type and source of geothermal fluid and to estimate the reservoir condition of Arjuno- Welirang geothermal system. Data are obtained from collecting water samples including hot springs, cold springs, river waters and rain water, then they are analyzed using ICP-AES, titration and ion chromatography.All thermal waters have temperatures from 39.5–53°C and weakly acidic pH (5.2–6.5). Cangar and Padusanhot springs show bicarbonate water, formed by steam condensing or groundwater mixing. On the other hand, Songgoriti shows Cl-HCO3 type, formed by dilution of chloride fluid by either groundwater or bicarbonate water during lateral flow. All of the waters represent immature waters, indicating no strong outflow of neutral Cl-rich deep waters in AWVC. Cl/B ratios show that all water samples have a similar mixing ratio, showing they are from common fluid sources. However, Padusan and Songgoriti have higher Cl/B ratios than Cangar, suggesting that geothermal fluids possibly have reacted with sedimentary rocks before ascending to the surface. All waters were possibly mixed with shallow groundwater and they underwent rock-water reactions at depth before ascending to the surface. An estimated temperatures reservoir calculated using CO2 geothermometer yielded temperatures of 262–263 °C based on collecting of fumarole gas at Mt. Welirang crater. According to their characteristics, Cangar and Padusan are associated with AWVC, while Songgoriti is associated with Mt. Kawi.

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Prasetio, Rasi, Neneng Laksminingpuri et Bungkus Pratikno. « Karakterisasi Isotop dan Geokimia Area Panas Bumi Danau Toba, Sumatera Utara ». Jurnal Ilmiah Aplikasi Isotop dan Radiasi 13, n^o 2 (20 décembre 2017) : 79. http://dx.doi.org/10.17146/jair.2017.13.2.3508.

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Danau Toba merupakan danau vulkanik terbesar di dunia dan memiliki aktifitas panasbumi. Terdapat dua wilayah di Danau Toba dengan manifestasi panasbumi berupa mata air panas, fumarol dan steaming ground, yaitu di daerah Simbolon dan Pusuk Buhit. Penelitian isotop dan geokima terhadap fluida manifestasi lapangan panas bumi telah dilakukan untuk mengetahui karakter sistem panas bumi tersebut. Pengambilan sampel mata air panas dilakukan untuk analisis kandungan kimia, isotop 18O dan 2H(deuterium) serta isotop 222Rn. Sampel gas diambil dari fumarol untuk analisis komposisi kimia gas. Interpretasi hasil analisis tersebut dimaksudkan untuk mengetahui karakteristik sistem panas bumi seperti asal-usul dan evolusi fluida, temperatur reservoir hingga model konseptual reservoirdanau Toba.Hasil analisis data menunjukkan bahwa area panasbumi danau Toba memiliki estimasi potensi panasbumi dengan temperatur 265°C di Pusuk Buhit dan 235°C di Simbolon. Berdasarkan data isotop stabil (18O dan 2H) dan gas, fluida panas bumi Toba merupakan fluida meteorik dengan sedikit kontribusi sumber magmatik. Namun demikian, komposisi isotop 18O fluida panas bumi di Pusuk Buhit mengalami pergeseran akibat interaksi air-batuan yang lebih intens dibanding fluida daerah Simbolon. Kandungan 222Rn yang rendah dalam sampel air panas menunjukkan adanya pencampuran fluida reservoir dengan air permukaan yang tidak mengandung 222Rn atau air tanah lokal dengan kandungan 222Rn yang sangat rendah.

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