В результате детального минералогического и петрохимического изучения известково-щелочных магнезиальных базальтов 21 эксплозивного и эффузивного побочного прорыва Ключевского вулкана, а также на основании данных геохимической термометрии получены новые сведения о химическом составе магнезиальных базальтов фенокристаллов оливинов и клинопироксенов в условиях их кристаллизации в промежуточных магматических камерах. На основе балансовых расчетов показано, что магнезиальные базальты являются продуктами исходных высок о магнезиальных магм.

This paper presents the results of visual observations, particle-size analysis, seismological observations, and acoustic measurements carried out during a small-magnitude eruption of Bezymyannyi in June 1986. A mlodel is proposed for the mechanism of the eruption. A specific character of the eruption is explained by a deeper localization of a gas-rich aagia portion in the conduit,

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.