GEOTECTONIC SETTINGS OF MODERN HYDROTHERMAL MANIFESTATIONS IN KAMCHATKA

Abstract

The bulk of the Kamchatkan hydrothermal manifestations and all high-temperature hydrothermal systems are located in three volcanic belts: the East Kamchatka, South Kamchatka, and Sredinnyi Ridge volcanic zones. The fact that subduction has terminated beneath the latter is confirmed by geological evidence and also by the fact that the amount of heat transferred by the Sredinnyi Ridge hot springs is an order of magnitude lower than that in East and South Kamchatka. The hydrothermal manifestations have an almost identical geographical distribution pattern in all of the three volcanic belts. With the 90-100-km widths of the volcanic belts and zones of hydrothermal activity, > 95% of the heat transferred by the hot springs are confined to the roughly 45-km wide zones that border the volcanic fronts. The volcanic fronts of the arcs are distinct boundaries, beyond which heat transfer declines abruptly. Heat transfer is restricted to zones with 70-100-km intervals between the peak heat transfer values. The quantitative evaluation of the contributions of potential heat and water sources revealed that the sole realistic heat source could be shallow magma chambers. A model is proposed for a potential heat and mass transfer mechanism responsible for the formation of hydrothermal systems and associated ore deposits.