Active Volcanoes and Thermal Springs of Kunashir Island (Russia)

Abstract

Since 2002, complex studies of all known thermal springs of Kunashir Island have been carried out. Of the four active volcanoes in the island, three volcanoes have stable hydrothermal systems. In addition to volcanoes, thermal springs in Kunashir are found on the coast and they are associated with tectonic faults. Despite the different morphogenetic types of volcanoes and their activity, the common patterns of zoning of hydrochemical types of thermal waters are typical for volcano-hydrothermal systems. On the periphery of the extrusive domes of the volcanoes, there are solfataric fields with outputs of gases and acid sulfate hydrotherms with temperatures up to 95 °C. Below the slope at a distance from the extrusive domes and solfataric fields an acid chloride-sulfate (sulfate-chloride) sodium hydrotherms with temperatures up to 91 °C are located. At the foot of volcanic edifices, at a considerable distance from the extrusions and outputs of solfataric gases, neutral chloride sodium thermal springs and steams are located. The isotopic composition of oxygen and hydrogen of different hydrochemical types of thermal waters is similar to the isotopic composition of local meteoric waters, which confirms the genesis of hydrotherms due to atmospheric waters with minimal participation of sea and "mantle" waters.