Review and analysis of genesis conditions for adakites and magnesian andesites with adakite properties showed that there are various tectonic and geodynamic settings within subduction zones of the Pacific Ring. These settings provide additional heating sufficient for slab melting in subduction zones. As a rule, on the initial stage of subduction process a front part of a new slab suffered melting caused by heat from hot asthenosphere. In this case, their association with NEB type can be traced. A large number of adakite location depend on additional heating and slab melting in slab windows regardless geodynamic conditions. Moreover, formation of adakites may probably be caused by subduction of hot spreding centers. Oblique subduction and transform interactions between plates may generate additional heating sufficient for adakite volcanism.

The authors studied deposits from pyroclastic flows associated with Karymsky Caldera, which is located in the central part of the Karymsky Volcanic Centre (KVC). The study distinguished 4 pyroclastic flows and revealed that deposits from each pyroclastic flow have stratification in composition distinctly observed in the initial phase of the eruption. The pumice debris and cores of plagioclase crystals in pumice give evidence for both upper rhyolite zone and lower dacite zone in the upper-crust magmatic chamber. The heterogeneous layers and non-equilibrium mineral association in pumice suggest that the initial phase of each eruption is caused by intrusion of basalt in the upper-crust magmatic chamber. The distribution of major and trace elements in pyroclastic rocks of Karymsky Caldera show that they have resulted from moderate calcareousalkali differentiates of magnesia-basalt of KVC. Mineralogical and geochemical data show that the fractional crystallization and crustal contamination play significant role in origin of the rocks.

Results from detailed field work made it possible to describe the geologic structure of Late Pleistocene Old Shiveluch Volcano. Old Shiveluch activity consisted of two phase: extrusive-explosive activity of the initial phase was followed by numerous lava effusions from several eruptive centers. Location of the eruptive centers was reconstructed along the rim of the destroyed southern part of the volcano. Three main types of rocks were distinguished in the Old Shiveluch edifice: magnesian andesites (SiO2=57.3-63.8 wt.%, Mg#=52.5-57.0 mol. %), high-Mg basaltic andesites (SiO2=53.9-55.0 wt.%, Mg#=58.8-63.7 mol.%) and high-Al basaltic andesites (SiO2=53.5-55.7 wt.%, Mg#=52.1-56.1 mol.%). Relative sequence and the approximate volume ratios of the different types of rocks were revealed. New geologic data allowed suggesting what caused a sector collapse of Old Shiveluch edifice.

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.

The article provides data on historical events of the Kurile island arc’s most active Peak Sarychev Volcano, Matua Island, the Central Kuriles. During the study period the volcano was producing short terminal eruptions of explosive and explosive-effusive types discharging volcanites chiefly with pyroclastic flows and related formations.

Mount Rannyaya (86°58' S, 163°20' W, 2270 m a.s.l., 18-20 Ма) и Sheridan Bluff (87°04' S, 153°46' W, 2720 m a.s.l., ~ 16 Ма) were explored in 1934 and 1962-1963, and studied and dated in 1978-1979 bу Antarctic researches. The article shows that these volcanoes are typical tuya, the oldest and high-latitude volcanoes on Earth. It confirms that in early Miocene thick glaciers existed in western Antarctic near the Pole, and subglacial volcanic activity was strong.

The paper provides updated information on recent activity of Sinarka Volcano, Shiashkotan Island, the Kurile Islands. The data was obtained during expeditions to the Central and Southern Kuriles in 2007-2008. Fumarolic and hydrothermal activity of the Central extrusive dome at Sinarka Volcano and Western and North-Eastern fumaroles fields are characterized. The research revealed certain change in fumarolic and hydrothermal activity of the volcano, in comparison to the data from previous investigations. A new thermal spring was revealed within the North-Eastern fumarole field, while other springs started to die. Fumaroles with temperature about 450°С revealed on the slope of the Central extrusive dome give evidence that Sinarka Volcano is currently highly active.

Geodynamic model of alkaline basaltoids with intraplate geochemical characteristics was developed on the base of systematization and analysis their space and time data in the East Kamchatka volcanic arc. The alkaline «intraplate» rocks in the East Kamchatka were formed as a result of partial melting at low degree of an «andersonian» type mantle plume. This mantle plume was generated in the astenosphere beneath the Pacific plate about 400-500 km from the deep sea trench similarly Hirano et al. (2006) flexure model and then was moved to the new forming East Kamchatka subduction zone by mantle convection. Adakites were produced by partial melting of the frontal part of the subducting Pacific plate in the initial stage of subduction. The model explains a short time of the formation of alkaline rocks, and their change by transitional rocks and adakites, and then by typical calk-alkaline rocks, and their position only in the subduction zone jump to the present-day position.