Вулканы... Они будоражат воображение. На Камчатке и Курильских островах люди живут рядом с вулканами, однако мало знают о них. Известный ученый, доктор геолого-минералогических наук В.К. Мархинин увлекательно рассказывает о вулканах, о своих трудных экспедициях на огнедышащие горы.

For the first time, the thermal behavior of a new mineral belomarinaite KNaSO4 was studied on a natural
sample and its synthetic analogue in the range of 30‒800°C. The mineral is stable up to a temperature of
475 ± 10°C, at which it has a polymorphic transformation into a high-temperature polymorphic modification
(P63/mmc), stable up to 800°C. The thermal expansion of both modifications is sharply anisotropic, and in
the case of the high-temperature phase it is also variable as a function of temperature ‒ the dependence of the
parameter a has a U-shape with a minimum at T = 660°C. The volumetric expansion of modifications varies
in the intervals of their existence for the low-temperature phase from 80 to 200 (10–6°C–1), for the high-temperature phase, from 350 to 300 (10–6°C–1). That is, on average, the expansion of the high-temperature modification increases by a factor of 2‒3 relative to the expansion of the low-temperature phase, the main increase is in the parameter с and is determined, apparently, by restructuring the structure along this direction.

Shiveluch is one of the most active explosive volcanoes worldwide. During the last рlinian eruption in 1964 and the following (1980-current time) dome-forming eruptions Shiveluch has produced andesites and dacites (SiO2~60-64 wt.%) containing variably zoned, compositionally and texturally diverse amphibole phenocrysts. In this work, we attempt to decode the complex zoning of the amphibole crystals in the 55-year series of pumice, dome rocks and mafic enclaves in order to reconstruct the most recent evolution of the volcano plumbing system.
The amphibole zoning in Shiveluch andesites reveals correlation with the style and date of eruption. High-Al cores mantled by low-Al rims in amphiboles from the 1964 plinian eruption record a drastic decrease of pressure and rapid magma ascent from the lower crust to the shallow magma chamber. Typically unzoned and often opacitized low-Al crystals from the early dome-building episodes in 1980-1981 and 1993-1995 reflect magma crystallization in the shallow magma chamber. Complexly zoned amphiboles from andesites erupted in 2000s indicate replenishment of the shallow magma chamber with mafic magma and syn-eruptive mixing processes. Amphibole-based barometric calculations obtained by different approaches indicate that the Shiveluch plumbing system is complex and comprises two, mafic and silicic magma storage zones at ~15-20 km and ~5-6 km depths. We suggest that both episodes of the plinian eruption in 1964 and the extensive dome growth in 2001-2016 were driven by influx of mafic magma in the shallow storage zone beneath Shiveluch. The mafic replenishment likely preceded the 1964 plinian eruption and repeatedly occurred during the period of extensive dome growth in 2001-2016. The variable styles of the recent Shiveluch eruptions may be controlled by the relative volume of the mafic recharges and their thermal and viscosity effects on the efficiency of magma mixing.

Mafic enclaves preserve a record of deep differentiation of primitive magmas in arc settings. We analyze the petrology and geochemistry of mafic enclaves from Shiveluch volcano in the Kamchatka peninsula to determine the differentiation histories of primitive magmas and to estimate their pressures, temperatures, and water contents. Amphibole inclusions in high forsterite olivine suggest that the primitive melt was superhydrous (i.e. >8 wt% H2O) and was fractionating amphibole and olivine early on its liquid line of descent. We find that the hydrous primitive melt had liquidus temperatures of 1062±48°C and crystallized high Mg# amphibole at depths of 23.6-28.8 km and water contents of 10-14 wt% H2O. The major and trace element whole rock chemistry of enclaves and of published analyses of andesites suggest that they are related through fractionation of amphibole-bearing assemblages. Quantitative models fractionating olivine, clinopyroxene, and amphibole reproduce geochemical trends defined by enclaves and andesites in variation diagrams. These models estimate 0.2%-12.2% amphibole fractionated from the melt to reproduce the full range of enclave compositions, which overlaps with estimates of the amount of amphibole fractionated from parental melts based on whole rock dysprosium contents. This contribution extends the published model of shallow processes at Shiveluch to greater depths. It provides evidence that primitive magmas feeding arc volcanoes may be more hydrous than estimated from other methods, and that amphibole is an important early fractionating phase on the liquid line of descent of superhydrous, primitive mantle-derived melts.