В работе представлены результаты исследования необычных минеральных образований идеальной сферической формы размером 0,5-2 мм из вулканических пород Курильских островов и Южной Камчатки. Описываются морфология, вещественный состав, внутреннее строение сферул, характеризуется комплекс сопутствующих минералов. Показывается характер распространения сферул в мощных толщах вулканических пород. Обсуждаются вопросы, связанные с их генезисом.
Рассматриваются вероятные механизмы и условия их образования. Установлено, что сферулы являются рудными, рудно-силикатными и силикатными каплями застывшего расплава. В большинстве случаев они сложены самородным железом и его оксидами, а также стеклом сложного состава с высокими содержанием Ti, Fe и Mn. Предполагается, что сферулы имеют магматическое происхождение, их образование и распространение в толщах вулканических пород связано с активной деятельностью вулканов.
Книга может представлять интерес для геологов широкого профиля, минералогов и специалистов, занимающихся изучением «космической пыли».

The Klyuchevskoi group of volcanoes (KGV) in Kamchatka is the most powerful existing island arc and subduction zone volcanic center. The Holocene volcanic activity in the southern part of the KGV is concentrated in a large basaltic volcano, Ploskii Tolbachik (PT), altitude 3085 m and in itsTolbachik zone of cinder cones (TZ), length 70 km, which are similar to Hawaiian-type volcanoes and their rifts. A variety of different basalt types are erupted at a rate of 18 x 106 t/yr. This paper provides information on the PT peripheral magma chamber obtained by several independent methods. We used data on the evolution, eruptions, magma discharge, deformation, and earthquakes in the PT and TZ, as well as calculations that give the size of the PT flow-through magma chamber. The use of seis- mological and geodetic data places the chamber under the PT summit caldera, gives its transverse size as below 6 km, and the top of the chamber at a depth of 2 km. Our calculations give 4.9-5.8 km for the transverse chamber dimension, 3.2-3.9 km for its vertical dimension, 40-70 km' for chamber volume, and about 4 km for the depth of chamber center. The information we provide makes the properties of this source of PT and TZ alumina-rich basalts clear, as well as those of the entire KGV complex plumbing system.

Over the period 2009-2010 the authors conducted a nuclear-geophysical investigation in Nalychevo Nature Park. Local anomalies with γ-radiation (I ≥ 20-30 µR/h) were detected within Kotel thermal area. The anomalies were caused by high radium concentration which deposited in travertine field of thermal spring’s sources. The authors also detected high levels of volumetric activity of radon in soil air caused, on one hand, by emanating collectors with high radium content in travertine within the zones of old sources of thermal springs and, on the other hand, by zones of fracture observed as negative landforms. Formation of travertine field at the non-natural thermal field «Grifon Ivanova» is accompanied by deposition of radium-bearing minerals within a few hundreds of meters away from the source with I ≥ 20-30 µR/h along the drain.

Caldera collapse changes volcanic eruption behavior and mass flux. Many models of caldera formation predict that those changes in eruption dynamics result from changes in conduit and vent structure during and after collapse. Unfortunately, no previous studies have quantified or described how conduits change in response to caldera collapse. Changes in pumice texture coincident with caldera formation during the 1800 14C yr BP KS1 eruption of Ksudach Volcano, Kamchatka, provide an opportunity to constrain magma decompression rates before and after collapse and thus estimate changes in conduit geometry. Prior to caldera collapse, only white rhyodacite pumice with few microlites and elongate vesicles were erupted. Following collapse, only gray rhyodacite pumice containing abundant microlites and round vesicles were erupted. Bulk compositions, phase assemblages, phenocryst compositions, and geothermometry of the two pumice types are indistinguishable, thus the two pumice types originated from the same magma. Geothermobarometry and phase equilibria experiments indicate that magma was stored at 100–125 MPa and 895 ± 5 °C prior to eruption. Decompression experiments suggest microlite textures observed in the white pumice require decompression rates of > 0.01 MPa s− 1, whereas the textures of gray pumice require decompression at ~ 0.0025 MPa s− 1. Balancing those decompression rates with eruptive mass fluxes requires conduit size to have increased by a factor of ~ 4 during caldera collapse. Slower ascent through a broader conduit following collapse is also consistent with the change from highly stretched vesicles present in white pumice and to round vesicles in gray pumice. Numerical modeling suggests that the mass flux and low decompression rates during the Gray phase can be accommodated by the post-collapse conduit developing a very broad base and narrow upper region.