No 4 (2019)

Processes responsible for variations in the isotopic composition (ΔD and Δ18O) of thermal waters of the Kuril islands arc
Kalacheva E.G., Taran Y.A.

Abstract

Many active volcanoes of the Kuril Islands host hydrothermal systems. Their surface manifestations are represented by numerous thermal springs showing diverse chemical composition and physical-chemical parameters. Four main isotopic shifts relative to the local meteoric water line can be observed in the corresponding δD vs. δ18O diagrams. For the acid Cl-SO4 waters there is a clear mixing trend between meteoric water and volcanic vapor. The acid SO4waters demonstrate trends indicating kinetic fractionation at temperatures close to the boiling-point. Isotopic composition of the coastal springs tend to march the mixing line between meteoric and seawater. The δ18O-shift for deep thermal water is accounted to of isotopic exchange with host rock. The latitude effect revealed for meteoric waters also observed in the isotopic composition of the thermal waters.

Вулканология и сейсмология. 2019;(4):3-17
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Numerical simulation of orthosilicic acid polycondensation and silica particles formation inhydrothermal solutions
Potapov V.V., Cerdan A.A., Kashutina I.A.

Abstract

Numerical simulation of the process of polycondensation of orthosilicic acid and colloid silica particles growth under different physical and chemical conditions was done: temperature, pH, ionic strength and other. Calculated dependences of orthosilicic acid concentration and mean radius of silica particles versus time, graphs of particles dimensions distributions were received. Results of calculations were compared with experimental data. Research is important for to make clear role of colloid silica on hydrothermal mineral formation and for industrial extraction and utilization of silica, and also for mineral synthesis.

Вулканология и сейсмология. 2019;(4):18-28
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Hydrothermal formations of pervenets rise (the Sea of Japan)
Astakhova N.V., Lopatnikov E.A., Mozherovsky A.V., Jaroshhuk E.I.

Abstract

The data are given on the structure, chemical composition, and content of microelements in the ferromanganese and siliceous crusts of Pervenets Rise (the Sea of Japan). The crusts resulted from the cementation of small fragments of green clays (celadonite) with hydroxides of manganese (todorokite and birnessite) or silica. Initial was the formation of celadonite deposited during the eruption of ore-bearing hydrothermal solutions in the volcano caldera or on its slopes.The features of the crust structure show that they were originated through the diffusive infiltration of gas-hydrothermal solutions along the fractures or weakened zones in volcanic rocks and subsequent cementation of the celadonite already formed occurrences with manganese or siliceous oxides. The manganese and siliceous mineralization is separated in time and often in space and demonstrate more local distribution.

Вулканология и сейсмология. 2019;(4):29-39
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Volcanism and geochemistry of soil and vegetation cover of Kamchatka. Communication 3. Elemental composition of vegetation of volcanic ecosystems
Zakharikhina L.V., Litvinenko Y.S.

Abstract

The link of the chemical composition of the plant with the active volcanism of Kamchatka, is determined by the stable occurrence into the composition of the priority chemical elements for plants, volcanic ashes and soils: Ca, Mg, Mn, P, Cu, Zn and Sr. An elevated geochemical background of Kamchatka plants relative to the bulk chemical composition of the peninsula’s soils was established. The contents of Br, Hg, Hf, Sb, Ga, W, K relative to the clarks for living matter in the plants of the region are exceeded by 3–5 times. Against the background of small variations in the contents of chemical elements in plants of different regions, the relatively rich biogeochemical background of the Western region of the southern province (the western coast of Kamchatka) is determined, where most ancient near-surface volcanic ashes for Kamchatka are transformed into humus-accumulative horizons. On the territory of young volcanic ash fallout in the immediate vicinity of volcanoes, the relative richness of vegetation with chemical elements and the poverty of soils by mobile forms of elements have been established. On the contrary, at a distance from the volcanoes in the zone of far transfer fallout ashes, there is a marked relative poverty of plants and soil richness of available chemical elements.

Вулканология и сейсмология. 2019;(4):40-51
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Experience of observing deformations of the earth's surface at small sites in rift zones in 1984–1995 in Kamchatka
Mironov I.K., Maguskin V.M.

Abstract

A review is given of high-precision measurements of distances by light-rangefinders and elevations from Class I leveling between long-term geodetic centers at local deformation sites laid on the coast of Avacha Bay, in order to detect deformation precursors of a likely strong earthquake (M > 7.0) and to obtain quantitative characteristics of co-seismic deformations. The report in tabular form contains the results of all measurements performed in the period 1984 –1995. These data are necessary for future researchers, since between the preserved centers you can repeat the measurements with any exact methods, compare them with the results of previous years and draw more objective conclusions. During the observations at all sites, no significant changes (exceeding the double accuracy of their determination) exceeded and the distances between the geodetic centers did not occur. The strong (M = 6.8) earthquake that occurred on March 2, 1992, with its epicenter in Avacha Bay did not cause precursors of deformations, and co-seismic deformations did not occur either. Perhaps they were, however, the sensitivity of the method and the remoteness of the sites from the hypocenter of the earthquake did not allow them to be detected.

Вулканология и сейсмология. 2019;(4):52-68
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The role of water in volcanism
Arsanova G.I.

Abstract

Water plays an extremely important role in volcanism: it acts as an evacuator of viscous melts in a variety of ways, which is ensured by the presence of relevant properties of its phase states, which successively changing with the fall of the environmental parameters. In this sense, the supercritical (fluid) state of water is especially significant. The paper provides a summary of fluid properties that are unique in many ways. The properties determine the relationship between water fluid and silicate melt, which in turn explains the cause of volcanic phenomena and the course of eruptions: explosions of different power, the emergence of the so-called fluidized mass, scorching clouds, landslides and breakthroughs on the slopes, the formation of ignimbrites, as well as the mechanism of gas transport to the foot of volcanoes.

Both by role and quantity, water is the main volcanic substance, which together with the silicate melt constitutes magma.

Вулканология и сейсмология. 2019;(4):69-80
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