On the basis of the chemical, isotopic and thermodynamic characteristics of fluids sampled between 1964 and 1989 a genetic model description is given for fumaroles of the Mutnovsky volcano. There are three individual groups of fumaroles in the Mutnovsky crater which show stable activity for a long period of time: “the Active Funnel” (temperatures exceed 600°C), the “Upper Field” (up to 320°C) and the “Bottom Field” (from 100 to 150°C). The three principal zones of emission have different gas composition, water isotopic composition, radioactivity and 3He/4He ratios. The abundance of magmatic components in the high-temperature fumaroles of the “Active Funnel” is much higher than those in gases from the other groups. Emission rate of SO2 from the “Active Funnel” is about 200 t/d, which requires complete degassing as a minimum of 1 km3 of magma every 20 years. Fluids of the “Upper Field” contain up to 80% of steam from the Mutnovsky geothermal system. Temperature variations of the “Bottom Field” fumaroles (from 97°C before 1982 to 151°C in 1989) result from changes in hydrological conditions in the crater. Evaporation of high-saline acid brine which is formed in the interior of the volcano is responsible for the composition of the “Bottom Field” gas-steam discharges.

Представлены данные по химическому и изотопному составу фумарольных газов и термальных вод, отобранных в кратере Мутновского вулкана за период с 1963 по 1989 г. Для интерпретации данных используется термодинамический подход, балансовые оценки, а также сведения о гидрогеологических особенностях Мутновского геотермального района и постройки вулкана. Три обособленные группы фумарольных выходов в кратерах вулкана, стабильно действующие на протяжении многих лет (Активная воронка, Верхнее поле и Донное поле), отличаются по составу газов, изотопному составу воды, а-активности и гелиевым отношениям. Показано, что в формировании состава фумарольных газов участвуют магматические флюиды, поверхностные и термальные воды, а также процессы кипения ультракислых рассолов - смешанных вод, образующих локальную гидротермальную систему Донного поля кратера Мутновского вулкана.

Data are presented about the chemical and isotopic composition of fumarolic gases and thermal water collected in the crater of the Mutnovskiy volcano from 1963 to 1989. A thermodynamic approach, balance estimates and information on the hydrogeological characteristics of the Mutnovskiy geothermal field and volcanic structure were used in the interpretation of the data. Three groups of fumarolic vents in the craters of the volcano have been active for many years (the Aktivnaya cone, the Verkhneye field and the Donnoye field) and differ in the composition of their gases, the isotopic composition of the water, a activity and He ratios. It was shown that the composition of the fumarolic gases is formed as a result of the interaction between the magmatic fluid, the surface and thermal waters and also the boiling of ultra-acidic brines-the mixed waters that form the local hydrothermal system of the Donnoye field in the crater of the Mutnovskiy volcano.

Рассматривается геодинамическая обстановка проявлений разных типов вулканизма, динамика процессов в коре и мантии вулканических областей по геофизическим данным, про блема эволюции вулканизма и его цикличности. Обсуждаются вопросы происхождения и эволюции магматических расплавов, проблемы эволюции теплового потока в пределах Тихоокеанского кольца и его связи с вулканическими и гидротермальными процессами, а также необратимость развития гидротермального процесса в ходе развития вулканизма складчатых областей.

Study of the largest manifestations of the recent hydrothermal activity in Uzon-Semyachik, Pauzhetka-Kambalny and other regions in Kamchatka enable us to conclude: in the area of recent volcanism characterized by a general increase of conductive heat flow, some regions can be distinguished with an especially intense geothermal regime specified by an additional supply of heat by deep fluids. Within such anomalies the formation of hydrothermal systems can be observed. Recent hydrothermal systems of Kamchatka are natural hydrodynamic systems belonging to the type of small artesian basins and artesian slopes having porous-bedded, fissure-bedded and more seldom fissure-veined permeability and containing high-temperature underground waters. They are associated with volcano-tectonic grabens and circular depressions filled with a series of tufaceous material of mainly acid composition and two-membered structure. Localization of certain thermal manifestations within the systems is determined by disjunctive tectonics and outflows of thermal waters to the surface. The same factors are responsible for the position of the recharge areas of the systems with infiltration waters forming the main mass of their water reserves. Usual hydrodynamic methods can be used for a quantitative estimation of these reserves. Heat recharge of the systems is realized by the supply of an over-critical fluid. This is confirmed by hydrogeothermal data, similarity of the chemical composition of high temperature hydrothermal water and their thermo-physical parameters. Manifestations of hydrothermal activity do not reveal any connection with recent andesite-basaltic volcanism of Kamchatka; on the contrary, they are associated with the acid volcanism of the Middle and Upper Pleistocene stage of its geological history, testifying to their genetic similarity. Hydrothermal activity is one of the manifestations of the general geothermal activity of the interior. It is closely related, in time and space, to a certain stage of the volcano-plutonic process and tectonic evolution of mobile belts. The perspectives of obtaining heat and electric energy from hydrothermal systems are considered.