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Records: 21
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Volcano observatory notification to aviation (VONA/KVERT). 2011.
Volkova Maria, Shapiro Nikolay, Melnik Oleg, Mikhailov Valentin, Plechov Pavel, Timoshkina Elena, Bergal-Kuvikas Olga Subsidence of the lava flows emitted during the 2012–2013 eruption of Tolbachik (Kamchatka, Russia): Satellite data and thermal model // Journal of Volcanology and Geothermal Research. 2022. doi: 10.1016/j.jvolgeores.2022.107554.
Volynets A.O., Melnikov D.V., Yakushev A.I. First data on composition of the volcanic rocks of the IVS 50th anniversary Fissure Tolbachik eruption (Kamchatka) // Doklady Earth Sciences. 2013. Vol. 452. № 1. P. 953-957. doi:10.1134/S1028334X13090201.    Annotation
First data on major, minor and trace element (XRF. ICP-MS) concentrations in the volcanic rocks of the IVS 50th anniversary Fissure Tolbachik eruption are reported for the period from 27.11.2012 to 25.01.2013; scheme of lava flows distribution by March 2013 is made. The volcanic rocks of the new eruption are substantially different from the other studied volcanic rocks of Tolbachinsky Dol by their higher alkalis and incompatible elements content. The rocks of the first three days of eruption (Menyailov Vent) have higher silica and alkalis content than all previously reported volcanic rocks of Tolbachinsky Dol. Volcanic rocks of the Naboko Vent, at silica content similar to high-Al basalts of Tolbachinsky Dol, have different concentrations of trace elements and some major elements (K2O, CaO, TiO2, P2O5). REE and other incompatible element concentrations in the rocks of the Menyailov Vent are higher than in the rocks of the Naboko Vent at the same element ratios. The differences of the volcanic rocks of the two vents of the new eruption may be caused by the fact that the erupted lavas came from the different levels of the same magma chamber.
Volynets Anna O., Edwards Benjamin R., Melnikov Dmitry, Yakushev Anton, Griboedova Irina Monitoring of the volcanic rock compositions during the 2012–2013 fissure eruption at Tolbachik volcano, Kamchatka // Journal of Volcanology and Geothermal Research. 2015. Vol. 307. P. 120 - 132. doi: 10.1016/j.jvolgeores.2015.07.014.    Annotation
Abstract Here we present the results from monitoring of the composition of rocks produced during the 2012–2013 fissure eruption at Tolbachik volcano (FTE). Major and trace element concentrations in 75 samples are reported. Products of this eruption are represented by high alumina basaltic trachyandesites with higher alkalis and titanium contents than in all previously studied rocks of the Tolbachik monogenetic volcanic field. Rocks erupted during the first three days (27–30 November) from the northern (also called Menyailov) group of vents are the most silica- and alkali-rich (SiO2 concentrations up to 55.35 wt. and {K2O} up to 2.67 wt.). From December onwards, when the eruptive activity switched from the Menyailov vents to the southern (Naboko) group of vents, silica content dropped by 2 wt., concentrations of MgO, FeO, TiO2 and Mg# increased, and {K2O} and Na2O concentrations and K2O/MgO ratio decreased. For the rest of the eruption the compositions of rocks remained constant and homogeneous; no systematic compositional differences between lava, bombs and scoria samples are evident. Trace element distributions in the rocks of the Menyailov and Naboko vent lavas are relatively uniform; Menyailov lavas have slightly higher Th, Nb, Hf, Y, and {HREE} concentrations than the Naboko vent lavas at more or less constant element ratios. We explain the initial change in geochemistry by tapping of a slightly cooler and fractionated (~ 3 Mt and 8 Cpx) upper part of the magma storage zone before the main storage area began to feed the eruption. Thermodynamic constraints show that apparent liquidus temperatures varied from 1142 °C to 1151 °C, and thermodynamic modeling shows that variations in compositions are consistent with a high degree of low pressure (100–300 MPa), nominally anhydrous fractionation of a parent melt compositionally similar to the 1975 Northern Breakthrough high-Mg basalt. Geochemistry, petrological observations and modeling are in agreement with the newly erupted material being derived from remnant high-Al magma from the 1975–76 Southern Breakthrough eruption with only slight amounts of cooling (less than 1 °C per year) during the intervening 36 years.
Volynets Anna, Melnikov Dmitry, Griboedova Irina Plagioclase lapilli and phenocrysts in the lavas of the 2012-2013 Tolbachik Fissure eruption // 8-th Biennial Workshop on Japan-Kamchatka-Alaska Subduction Processes, JKASP 2014. 22-26 September, 2014, Sapporo, Japan. 2014.    Annotation
The 2012-2013 Tolbachik Fissure eruption started from lava gushing and effusion in the Menyailov vent on November 27 th , 2012; after three days the activity of this vent ceased and the eruption continued from the Naboko vent until its end in September 2013. The eruption produced about 0.7 km 3 of high-Al basaltic trachyandesites (Dvigalo et al., 2014). At Menyailov vent SiO2 concentrations were as high as 55.35 wt.% and K2O -2.67 wt.% -higher than in any previously erupted rocks in Tolbachik monogenetic area. From the beginning of December, SiO 2 concentration in lavas dropped by 2 wt.% and remained at this level until the end of eruption. MgO, TiO2, Mg# increased, K2O, Na2O decreased slightly. Most prominent change we observe in K2O/MgO ratio, which was about 0.7 in the Menyailov vent rocks and became 0.5 in the Naboko vent rocks. Details of the geochemical composition of the volcanic rocks produced by this eruption are reported elsewhere (Volynets et al., 2013, Volynets et al., 2014 a, b); here we present the results of the geochemical study of the main phenocrysts in the lavas – plagioclase. For the detailed geochemical study of the plagioclase we selected two samples from the Naboko vent (Pl-phyric lavas, erupted in February and August) and five crystal lapilli (two of them were erupted in December 2012, and three – during 2013, when the new cone has been already built). Plagioclases in these lavas are represented by two generations of labradorite and bytownite. Pl phenocrysts of the 1 st generation are large (up to 2 cm on the long axis) strongly resorbed at the edges and sometimes in the cores as well, containing lots of glass inclusions. Pl subphenocrysts of the 2 nd generation are smaller (less than 500 µm), usually nonresorbed and clean, having euhedral facets. Normal, reversed and patchy zoning are typical for all studied crystals (fig.1, I and II). Maximum concentrations of An (up to 83% at compositional variation between An50 and 74) has been measured in the patchy zones. Crystal lapilli are characterized by the oscillatory zoning with An fluctuations around An57-63 (fig. 1, III and IV). This kind of zoning is the result of the diffusion control of Pl growth at low growth rates (Sibley et al., 1976). The edges of lapilli are usually rich of glassy inclusions, tunnel-like dissolution structures, Ol, Px, Mt inclusions (fig. 1, III and IV). There are abundant resorption zones in lapilli, with plenty of glassy inclusions. These zones are characterized by the patchy zoning with An concentration jumps up to An74; usually these high-An areas are observed near the inclusions of glass. At the edges of lapilli there are zones with An gradual decrease towards the rim from An 74 to An61.

Plagioclase lapilli and phenocrysts in the lavas of the 2012-2013 Tolbachik Fissure eruption.
Volynets Anna, Melnikov Dmitry, Yakushev Anton, Tolstykh Maria Petrology and geochemistry of the New Tolbachik Fissure Eruption volcanic rocks and their evolution during the first two weeks of eruption // IAVCEI 2013 Scientific Assembly. July 20 - 24, Kagoshima, Japan. 2013. P. 743
Volynets O.N., Flerov G.B., Andreev V.N., Popolitov E.I., Abramov V.A., Petrov L.L., Shcheka S.A., Selivanova G.I. Geochemical features of the rocks of the Great Tolbachik Fissure Eruption 1975–1976 in relation to petrogenesis / The Great Tolbachik Fissure Eruption. Cambridge: Cambridge University Press. Cambridge: Cambridge University Press. 1983. P. 116-140.
Volynets O.N., Melekestsev I.V., Ponomareva V.V., Yogodzinski G.M. Kharchinsky and Zarechnyi volcanoes - unique centers of late Pleistocene magnesian basalts in Kamchatka: Structural setting, morphology, geologic structure and age // Volcanology and Seismology. 1999. Vol. 20. № 4-5. P. 383-399.    Annotation
This paper presents the results of studying the spatial distribution and structural setting of magnesian basalts and andesites in the Northern group of Kamchatkan volcanoes and in the junction zone of the Kuril-Kamchatka and Aleutian island arcs. The morphology and geologic structure of unique Kamchatkan magnesian basalt stratovolcanoes are described: Kharchinsky, Zarechnyi, and the Kharchinsky regional zone of cinder cones. The reported evidence includes the ages and eruptive histories, and productivities of the volcanoes and the volumes and weights of their edifices. The magnesian basalts were erupted 40-50 thousand years ago, for the first time during the Holocene.
Volynets O.N., Melekestsev I.V., Ponomareva V.V., Yogodzinski J.M. Kharchinskii and Zarechnyi volcanoes, unique centers of Late Pleistocene magnesian basalts in Kamchatka: Composition of erupted rocks // Volcanology and Seismology. 1999. Vol. 21. № 1. P. 45-66.    Annotation
Most of the Kharchinskii and Zarechnyi products, as well as those of the Kharchinskii cinder cones, are magnesian rocks. Mineralogical data suggest that both the basaltic and the andesitic magma were rich in water (≥3-4 and >6-7 wt., respectively) and crystallized at high oxygen fugacity (2.0-2.5 orders of magnitude higher than the NNO buffer). These features, coupled with the geochemical characteristics of these basalts and andesites, indicate that they are similar to the rocks of Shiveluch, a volcano also located on the northern flank of the Northern volcanic group, but differ from the rocks of the other volcanoes of this group which are located further south. The Kharchinskii, Zarechnyi, and Shiveluch magnesian basalts differ from the rocks of the Klyuchevskoi volcano and Tolbachik lava field by their higher K, Ba, Sr and lower Ca, Sc, Yb contents at higher La/Yb, Ni/Sc, and La/Ta ratios, while their initial magmas were more hydrous and more oxidized.
Volynets O.N., Ponomareva V.V., Babansky A.D. Magnesian Basalts of Shiveluch Andesite Volcano, Kamchatka // Petrology. 1997. Vol. 5. № 2. P. 206-221.    Annotation
The eruptive history of the Shiveluch andesite volcano included two Holocene events, during which
the volcano erupted unusual rocks: medium-potassium, amphibole-bearing magnesian basalts (7600 years ago)
and high-potassium magnesian basalts with phlogopite and amphibole (3600 years ago). The volumes of tephra
were approximately 0.1 and 0.3 km3, respectively. Some of the mineralogical and geochemical features of the
Holocene basalts were inherited by the subsequent basaltic andesites and andesites. These are similar in Mg
variation ranges of olivine, clinopyroxene, and amphibole phenocrysts, high Mg contents, and high Cr and Ni
concentrations. This and the results of mass-balance calculations do not contradict the view that the Shiveluch
volcanic rocks originated during the crystal fractionation of Holocene basalt melts. However, the other
geochemical features of the Shiveluch rocks, e.g., their similar REE contents, cast doubt on the formation of
the magnesian basaltic andesites through fractional crystallization of magnesian basalt magma and suggest that
they originated as a result of interaction between magnesian basalt magma and a depleted mantle material at a
shallow depth. At the same time, the different mineral compositions of the Holocene medium- and high-potassium
basalts and the results of mass-balance calculations indicate that their parental magmas might be produced
by the melting of different rocks.

Андезитовый вулкан Шивелуч в голоценовое время дважды извергал необычные для него породы:
амфиболсодержащие магнезиальные умереннокалиевые базальты (7600 лет назад) и магнезиаль-
ные высококалиевые базальты с флогопитом и амфиболом (3600 лет назад). Объем тефры соста-
вил примерно 0.1 и 0.3 км3 соответственно. Некоторые минералогические и геохимические особен-
ности голоценовых базальтов, например близкий диапазон вариаций магнезиальное™ вкрапленни-
ков оливина, моноклинного пироксена и амфибола, повышенная магнезиальность пород и
повышенные содержания в них Сг и Ni, наследуются андезитобазальтами и андезитами вулкана Ши-
велуч. Эти обстоятельства, а также результаты масс-балансовых расчетов не противоречат гипоте-
зе о происхождении эффузивов вулкана Шивелуч в процессе кристаллизационной дифференциации
расплавов голоценовых базальтов. Однако другие геохимические особенности рассматриваемых
пород, например близкие содержания редкоземельных элементов в них, делают маловероятной воз-
можность образования магнезиальных андезитобазальтов путем фракционной кристаллизации рас-
плава магнезиального базальта, но позволяют предполагать их формирование в процессах взаимо-
действия таких расплавов с веществом деплетированной мантии на малых глубинах. В то же время
различие в минералогическом составе голоценовых умеренно- и высококалиевых базальтов и ре-
зультаты балансовых расчетов могут служить доказательством различных источников выплавле-
ния исходных расплавов для этих пород.