Geochemistry and solute fluxes of volcano-hydrothermal systems of Shiashkotan, Kuril Islands

Abstract

Shiashkotan Island belongs to the Northern Kuril island arc and consists of two joined volcanoes, Sinarka and Kuntomintar, with about 18 km of distance between the summits. Both volcanoes are active, with historic eruptions, and both emit fumarolic gases. Sinarka volcano is degassing through the extrusive dome with inaccessible strong and hot (N400°C) fumaroles. A large fumarolic field of the Kuntomintar volcano situated in a wide eroded caldera-like crater hosts many fumarolic vents with temperatures from boiling point to 480°C. Both volcanoes are characterized by intense hydrothermal activity discharging acid SO 4 -Cl waters, which are drained to the Sea of Okhotsk by streams. At least 4 groups of near-neutral Na-Mg-Ca-Cl-SO 4 springs with temperatures in the range of 50-80°C are located at the sea level, within tide zones and discharge slightly altered diluted seawater. Volcanic gas of Kuntomintar as well as all types of hydrothermal manifestations of both volcanoes were collected and analyzed for major and trace elements and water isotopes. Volcanic gases are typical for arc volcanoes with 3 He/ 4 He corrected for air contamination up to 6.4 R a (R a = 1.4 × 10 −6 , the air ratio) and δ 13 C (CO 2 ) within −10‰ to −8 ‰ VPDB. Using a saturation indices approach it is shown that acid volcanic waters are formed at a shallow level, whereas waters of the coastal springs are partially equilibrated with rocks at~180°C. Trace element distribution and concentrations and the total REE depend on the water type, acidity and Al + Fe concentration. The REE pattern for acidic waters is unusual but similar to that found in some acidic crater lake waters. The total hydrothermal discharge of Cl and S from the island associated with volcanic activity is estimated at ca. 20 t/d and 40 t/d, respectively, based on the measurements of flow rates of the draining streams and their chemistry. The chemical erosion of the island by surface and thermal waters is estimated at 27 and 140 ton/km 2 /year, respectively, which is 2-3 times lower than chemical erosion of tropical volcanic islands.

Geochemistry of REE, Zr and Hf in a wide range of pH and water composition: The Nevado del Ruiz volcano-hydrothermal system (Colombia)

“…8) are characterized by strong LREE depletion. A similar shape of pattern with LREE depletion was already observed in other acid-sulphate waters from Waiotapu (New Zealand), Copahue volcano (Argentina), Santa Ana (El Salvador), Kawah Ihen Crater Lake (Indonesia) and Kutomintar and Sinarka volcanoes (Kawah Ijen) (Takano et al, 2004;Wood et al, 2006;Varekamp et al, 2009;Colvin et al, 2013;Kalacheva et al, 2015). Strong REE fractionation occurs during the hydrothermal alteration in very low pH waters with high SO 4 2− contents, showing higher LREE contents in alunitic advanced argillic alterated rocks compared to the unalterated volcanic rocks (Hikov, 2011).…”

Geochemical characterisation of Taal volcano-hydrothermal system and temporal evolution during continued phases of unrest (1991–2017)

“…The alteration mineral assemblage found in the Main Crater of Taal volcano corresponds to alunite-rich advanced argillic alteration and the current MCL fluids correspond to the associated fluids, so REE fractionation at Taal is likely related to intensive interaction of fluids with mature rocks that have been heavily leached and altered. A similar REE pattern has been seen before in other volcanic lakes and hot springs, including Maly Semiachik, Russia; Kusatsu-Shirane, Japan; Keli Mutu, Indonesia; Santa Ana, El Salvador; Nevado del Ruiz, Colombia; Kutomintar and Sinarka volcanoes, Kuril Islands and Azufral, Colombia (Takano et al, 2004;Colvin et al, 2013;Inguaggiato et al, 2015;Kalacheva et al, 2015;Varekamp, 2015;Inguaggiato et al, 2017).…”

Determination of Abundances of Fifty‐Two Elements in Natural Waters by ICP‐MS with Freeze‐Drying Pre‐concentration

“…Determination of element abundances of natural fluids is, however, difficult because of the small quantities of elements that they contain, as low as fg g −1 level (Kalacheva et al . ). To determine element abundances in natural waters, therefore, the elemental pre‐concentration of elements prior to analysis has been proposed.…”