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Селянгин О.Б. Контаминация магмы, особенности петрогенезиса и распределение рудного вещества в породах никеленосной формации Срединно-Камчатского массива (часть вторая) // Вестник КРАУНЦ. Серия: Науки о Земле. 2018. Вып. 39. № 3. С. 9-25. doi: 10.31431/1816-5524-2018-3-39-9-25.
The article presents a discussion of contaminants in nickeliferous magmas of various composition and phase as metamorphic rocks and fluids. It describes distribution of different solid-phase contaminants (xenoliths) in intrusions and compositionally different accumulative rocks. Xenogenic material is represented both by host rocks with intrusions and deeper rocks with no surface outcropping. In order to estimate contamination effect on the variety of accumulative rock series and location of sulphide ores as a benchmark standard we use similar data on a ore-bearing intrusive rocks formed by nearly non-contaminated high-magnesian (parental) magma. Besides, the article describes contamination of magma by high-alumina coal slates as well as variety of forming series of its cumulative rocks and exotic floatation graphite-sulphide ores in aluminous granodiorites in one of the intrusive bodies.
Фирстов П.П., Лобачева М.А. Волновые возмущения в атмосфере, сопровождавшие извержение вулкана Камбальный (Камчатка) в 2017 г. // Вестник КРАУНЦ. Серия: Науки о Земле. 2018. Вып. 38. № 2. С. 45-58.
On March 24, 2017 Kambalniy Volcano started to erupt after a 500-year-long period of rest. The eruption continued till April 10, 2017. The paper provides the analysis of atmospheric wave disturbances as wavetrains of quasi-sinusoidal oscillations with a frequency of 8 Hz ("acoustic tremor" or AT), which occurred at certain moments during the eruption. Besides, the paper describes 3 strongest seismic signals registered at the initial stages of the eruptions simultaneously with AT, which was registered using an infrasound station IS44 installed 208 km NW far from the volcano. The nearest "Pauzhetka" seismic station installed 19 far from the volcano allowed monitoring the seismic build-up, which was short (2 days) and weak (Кmax = 8.6). Lack of definite discrete infrasound signals, which are usually caused by non-stationary process during explosive eruptions, gives evidence for peculiar pattern of formation and effusion of ash-and-gas emissions. Such uncommon acoustic radiations and seismic build-up prove the presumption that this eruption should be classified as a hydrothermal event.
Хубуная С.А., Гонтовая Л.И., Соболев А.В., Хубуная В.С. К вопросу о магматических очагах под вулканом Ключевской (Камчатка) // Вулканология и сейсмология. 2018. № 2. С. 14-30.
Numerous summit and parasitic eruptions of moderate potassium magnesian and high-alumina basalts and basaltic andesites, their mineralogic and geochemical features, and the composition of in situ chilled melt inclusions in the olivine of cinder lapilli discharged by Klyuchevskoi Volcano all provide evidence of the presence of magma chambers beneath the volcano. This is also supported by a dualism in the variation of CaO and A1203 concentrations in olivine and clinopyroxene during crystallization. The mineralogic features in the high-alumina basalts that were discharged by all parasitic eruptions of Klyuchevskoi provide evidence of magnesian magma being emplaced from a deeper chamber into a shallow high-alumina chamber. The distribution of incoherent elements in the volcano's magnesian and aluminiferous rocks shows that they came from a single mantle source. The geochemical and mineralogic data are in good agreement with the results of geophysical surveys that concern the structure and properties of the lithosphere beneath Klyuchevskoi.
Belousov A., Belousova M., Kozlov D. The distribution of tephra deposits and reconstructing the parameters of 1973 eruption on Tyatya volcano, Kunashir, Kurile Islands // Journal of Volcanology and Seismology. 2017. Vol. 11. № 4. P. 285-294.
Bergal-Kuvikas Olga, Nakagawa Mitsuhiro, Kuritani Takeshi, Muravyev Yaroslav, Malik Nataliya, Klimenko Elena, Amma-Miyasaka Mizuho, Matsumoto Akiko, Shimada Shunjiro A petrological and geochemical study on time-series samples from Klyuchevskoy volcano, Kamchatka arc // Contributions to Mineralogy and Petrology. 2017. Vol. 172. № 5. doi:10.1007/s00410-017-1347-z.
Churikova Tatiana, Gordeychik Boris, Wörner Gerhard, Flerov Gleb, Hartmann Gerald, Simon Klaus Geochemical evolution of Bolshaya Udina, Malaya Udina, and Gorny Zub volcanoes, Klyuchevskaya Group (Kamchatka) // Geophysical Research Abstracts. 2017. Vol. 19. P. EGU2017-10691.
The Klyuchevskaya group of volcanoes (KGV) located in the northern part of Kamchatka has the highest magma production rate for any arc worldwide and several of its volcanoes have been studied in considerable detail [e.g. Kersting & Arculus, 1995; Pineau et al., 1999; Dorendorf et al., 2000; Ozerov, 2000; Churikova et al., 2001, 2012, 2015; Mironov et al., 2001; Portnyagin et al., 2007, 2015; Turner et al., 2007]. However, some volcanoes of the KGV including Late-Pleistocene volcanoes Bolshaya Udina, Malaya Udina, Ostraya Zimina, Ovalnaya Zimina, and Gorny Zub were studied only on a reconnaissance basis [Timerbaeva, 1967; Ermakov, 1977] and the modern geochemical studies have not been carried out at all. Among the volcanoes of KGV these volcanoes are closest to the arc trench and may hold information on geochemical zonation with respect to across arc source variations. We present the first major and trace element data on rocks from these volcanoes as well as on their basement. All rocks are medium-calc-alkaline basaltic andesites to dacites except few low-Mg basalts from Malaya Udina volcano. Phenocrysts are mainly olivine, pyroxene, plagioclase and magnetite, Hb-bearing andesites and dacites are rarely found only in subvolcanic intrusions at Bolshaya Udina volcano. Lavas are geochemically similar to the active Bezymianny volcano, however, individual variations for each volcano exist in both major and trace elements. Trace element geochemistry is typical of island arc volcanism. Compared to KGV lavas all studied rocks form very narrow trends in all major element diagrams, which almost do not overlap with the fields of other KGV volcanoes. The lavas are relatively poor in alkalis, TiO2, P2O5, FeO, Ni, Zr, and enriched in SiO2 compared to other KGV volcanics and show greater geochemical and petrological evidence of magmatic differentiation during shallow crustal processing. Basement samples of the Udinskoe plateau lavas to the east of Bolshaya Udina volcano have similar geochemical composition (trace element enriched high-K basaltic andesites and andesites) and similar eruption age of 274 ka [Calkins et al., 2004] as typical plateau lavas below the northern KGV. This research was supported by RFBR-DFG grant # 16-55-12040.
Flerov G.B., Churikova T.G., Anan'ev V.V. The Ploskie Sopki volcanic massif: Geology, petrochemistry, mineralogy, and petrogenesis (Klyuchevskoi Volcanic Cluster, Kamchatka) // Journal of Volcanology and Seismology. 2017. Vol. 11. Vol. 4. P. 266-284. doi: 10.1134/S0742046317040030.
This paper is concerned with the geological history and petrology of a major polygenic volcanic edifice dating back to Upper Pleistocene to Holocene time. This long-lived volcanic center is remarkable in that it combines basaltic and trachybasaltic magmas which are found in basaltic andesite and trachybasaltic– trachyandesite series. The inference is that the coexisting parent magmas are genetically independent and are generated at different sources at depth in an upper mantle volume. The associated volcanic rocks have diverse compositions, stemming from a multi-stage spatio–temporal crystallization differentiation of the magmas and mixing of these in intermediate chas.
Girina O.A., Manevich A.G., Melnikov D.V., Nuzhdaev A.A., Petrova E. Kamchatka and North Kurile Volcano Explosive Eruptions in 2016 and Danger to Aviation // JpGU-AGU Joint Meeting 2017 Abstracts. Chiba, Japan: Japan Geoscience Union. 2017.
Gordeychik Boris, Churikova Tatiana, Kronz Andreas, Simakin Alexander, Wörner Gerhard Olivine zoning in high-Mg basalts of the Shiveluch volcano (Kamchatka) // Geophysical Research Abstracts. 2017. Vol. 19. P. EGU2017-10473.
Shiveluch volcano located in northern Kamchatka erupted mainly high-Mg andesites during Holocene times. However, tephrochronologists found two Holocene tephra layers that are unusual for this volcano: a high-Mg middle-K basalts with an age of 7600 yr BP and high-Mg high-K basalt with an age of 3600 yr BP [Volynets et al, 1997]. The proximal outcrops for these two tephra deposits were discovered just recently [Churikova et al., 2010; Gorbach & Portnyagin, 2011]. Our study of olivines from the high-Mg basalts documents unusual Mg-Fe zonation [Gordeychik et al., 2016]: Inner cores of olivines from both eruptions show Fo87-92, falling to the rim to Fo75-85. In the outer cores of both basalt tephra, forsterite decreases linearly abruptly changing to a steeper gradient towards the rim. Electron microprobe element maps reveal the complex and highly unusual zoning features of these olivines.
The inner cores of the olivines of 7600 yr BP tephra have bell-shaped distributions for forsterite and nickel. The maximum forsterite in their core can be up to Fo92, decreasing outward to the outer core to Fo86. At the same time, the trace elements in the inner core remain constant. Such element distribution is consistent with diffusion of Fe, Mg, and Ni in the initially uniform high Mg cores after the phenocrysts were changed to non-equilibrium in a less mafic melt. The shape of the inner cores suggests partial dissolution after magma mixing. The interfaces between the inner and outer cores are marked by abundant melt/fluid inclusions. The inner cores were overgrown by olivine with Fo90 when the crystals moved to the high-Mg melt. As result some olivine grains have the maximum forsterite values in the outer core. The specific feature of the olivine outer cores from basalt of the 7600 yr BP tephra eruption are concentric zones with higher values of Ca, Cr, Al, P. One of the crystals has five distinct growth zones with high Cr concentrations. The width of these zones can be only a few microns and thus such zones are often missed in typical quantitative point measurements in microprobe profiles.
Inner cores of olivines from the 3600 yr BP tephra are uniform in forsterite and nickel. However, Al and Ca element distribution maps show in inner cores higher concentrations with rather smooth contours. This suggests that initially the olivines were formed from high-Al and high-Ca melt, then were dissolved and the overgrowth zonation has been smoothed out due to faster Mg-Fe diffusion. Only Ca and Al with low diffusivity were conserved. The concentric zones with higher element concentrations are not so well expressed in olivines from the 3600 yr BP tephra, but some distinct growth zones are also shown in Ca, Cr, and P.
Information extraction and decoding of the elemental maps allow seeing highly complex growth-dissolutiondiffusion history of magma mixing processes prior to eruption. This research was supported by RFBR-DFG grant # 16-55-12040.
Kiryukhin A.V., Fedotov S.A., Kiryukhin P.A., Chernykh E.V. Magmatic plumbing systems of the Koryakskii–Avacha Volcanic Cluster as inferred from observations of local seismicity and from the regime of adjacent thermal springs // Journal of Volcanology and Seismology. 2017. Vol. 11. № 5. P. 321-334. doi:10.1134/S0742046317050049.
An analysis of local seismicity within the Avacha–Koryakskii Volcanic Cluster during the 2000–2016 period revealed a sequence of plane-oriented earthquake clusters that we interpret as a process of dike and sill emplacement. The highest magmatic activity occurred in timing with the 2008–2009 steam–gas eruption of Koryakskii Volcano, with magma injection moving afterwards into the cone of Avacha Volcano (2010–2016). The geometry of the magma bodies reflects the NF geomechanical conditions (tension and normal faults, Sv >SHmax >Shmin ) at the basement of Koryakskii Volcano dominated by vertical stresses Sv, with the maximum horizontal stress SHmax pointing north. A CFRAC simulation of magma injection into a fissure under conditions that are typical of those in the basement of Koryakskii Volcano (the angle of dip is 60о, the size is 2 × 2 km2, and the depth is –4 km abs.) showed that when the magma discharge is maintained at the level of 20000 kg/s during 24 hours the fissure separation increases to reach 0.3 m and the magma injection is accompanied by shear movements that occur at a rate as high as 2 × 10–3 m/s, thus corresponding to the conditions of local seismic events with Mw below 4.5. We are thus able to conclude that the use of planeoriented clusters of earthquakes for identification of magma emplacement events is a physically sound procedure. The August 2, 2011 seismicity increase in the area of the Izotovskii hot spring (7 km from the summit of Koryakskii Volcano), which is interpreted as the emplacement of a dike, has been confirmed by an increase in the spring temperature by 10–12°С during the period from October 2011 to July 2012.