Hydrothermal Solute Flux from Ebeko Volcanic Center, Paramushir, Kuril Islands

Abstract:

Ebeko volcano on the northern part of Paramushir Island, Northern Kurils, is characterized by frequent phreatic eruptions, a strong low-temperature fumarolic activity at the summit and was the object of comprehensive volcanological and geochemical studies during the last half a century. The volcanic center is composed of several Pleistocene volcanic structures aadjacent to Ebeko and hosts a hydrothermal system with a high outflow rate of hot SO4-Cl acidic water (Upper Yurieva springs) with the current maximum temperature of ~85^oC, pH 1.3 and TDS ~ 10 g/L. All discharging thermal waters are drained by the Yurieva River to the Sea of Okhotsk. The hot springs have been changing in time, generally decreasing their activity from near boiling in 1960s, with TDS ~ 20 g/L and the presence of a small steaming field at the upper part of the ~ 700 m long discharging area, to a much lower discharge rate of main vents, lower temperature and the absence of the steaming ground. The spring chemistry did not react to the Ebeko volcanic activity (14 strong phreato-magmatic events during the last 60 years).

The total measured outputs of chloride and sulfur from the system last time (2006-2010) were estimated on average as 730 g/s and 980 g/s, respectively, which corresponds to the equivalent fluxes of 64 t/d of HCl and 169 t/d of SO₂. These values are higher than the fumarolic volatile output from Ebeko. The estimated discharge rate of hot (85^oC) water from the system with ~ 3500 ppm of chloride is about 0.3 m³/s which is much higher than the thermal water discharge from El Chichon or Copahue volcano-hydrothermal systems and among the highest hot water natural outputs ever measured for a volcano-hydrothermal system.

We also report the chemical composition (major and ~ 60 trace elements including REE) of water from the main hot spring vents and the Yurieva river mouth.