Volcano–hydrothermal system of Ebeko volcano, Paramushir, Kuril Islands: Geochemistry and solute fluxes of magmatic chlorine and sulfur

Abstract

Ebeko volcano at the northern part of Paramushir Island in the Kuril island arc produces frequent phreatic eruptions and relatively strong fumarolic activity at the summit area~1000 m above sea level (asl). The fumaroles are characterized by low-temperature, HCl-and S-rich gas and numerous hyper-acid pools (pH b 1) without drains. At~550 m asl, in the Yurieva stream canyon, many hot (up to 87°C) springs discharge ultra-acidic (pH 1-2) SO 4 -Cl water into the stream and finally into the Sea of Okhotsk. During quiescent stages of degassing, these fumaroles emit 1000-2000 t/d of water vapor, b 20 t/d of SO 2 and b 5 t/d of HCl. The measurement of acidic hot Yurieva springs shows that the flux of Cl and S, 60-80 t/d each, is independent on the volcanic activity in the last two decades. Such high flux of Cl is among the highest ever measured in a volcano-hydrothermal system. Oxygen and hydrogen isotopic composition of water and Cl concentration for Yurieva springs show an excellent positive correlation, indicating a mixing between meteoric water and magmatic vapor. In contrast, volcanic gas condensates of Ebeko fumaroles do not show a simple mixing trend but rather a complicated data suggesting evaporation of the acidic brine. Temperatures calculated from gas compositions and isotope data are similar, ranging from 150 to 250°C, which is consistent with the presence of a liquid aquifer below the Ebeko fumarolic fields. Saturation indices of non-silicate minerals suggest temperatures ranging from 150 to 200°C for Yurieva springs. Trace elements (including REE) and Sr isotope composition suggest congruent dissolution of the Ebeko volcanic rocks by acidic waters. Waters of Yurieva springs and waters of the summit thermal fields (including volcanic gas condensates) are different in Cl/SO 4 ratios and isotopic compositions, suggesting complicated boiling-condensationmixing processes.

Gas Emissions From Volcanoes of the Kuril Island Arc (NW Pacific): Geochemistry and Fluxes

“…The postglacial cone of Ebeko is composed of lava flows and pyroclastics of andesitic composition. A short review of the phreatic activity of the volcano since that event can be found in Kalacheva et al (2016). The modern phreatic and fumarolic activity of Ebeko started after a strong explosive phreatic-magmatic eruption from the Middle crater in 1934-1935(Gorshkov, 1970Melekestsev et al, 1993).…”

“…4.1.5. Some of the data for Ebeko fumaroles are taken from other sources (Kalacheva et al, 2016;Menyailov et al, 1985). Some of the data for Ebeko fumaroles are taken from other sources (Kalacheva et al, 2016;Menyailov et al, 1985).…”

“…Some of the data for Ebeko fumaroles are taken from other sources (Kalacheva et al, 2016;Menyailov et al, 1985). The reason for such a high chloride content and relatively isotopically light water in the low-temperature fumarolic gas of Ebeko have been discussed in Kalacheva et al (2016). The reason for such a high chloride content and relatively isotopically light water in the low-temperature fumarolic gas of Ebeko have been discussed in Kalacheva et al (2016).…”

“…More points for Ebeko are plotted using data fromKalacheva et al (2016) andMenyailov et al (1985). Dotted lines show the average C/S values measured by the MultiGas analyzer.…”

Sulfur Degassing From Steam‐Heated Crater Lakes: El Chichón (Chiapas, Mexico) and Víti (Iceland)

“…Recent Multi-GAS compositional measurements in the plumes of hyperacidic crater lakes (de Moor et al, 2016;Gunawan et al, 2016;Shinohara et al, 2015;Tamburello et al, 2015) have shown that SO 2 escapes through lake-water surfaces during pH < 1 gas-water interactions. HCl, another acidic gas species generally considered reactive in aqueous solutions, was detected in emissions from hyperacid springs (e.g., Kalacheva et al, 2016). Recently, Capaccioni et al (2017) and Rodríguez et al (2017) experimentally demonstrated that HCl is increasingly released from a "lab-lake" when pH drops below À0.2.…”