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Records: 2397
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Olivine zoning in high-Mg basalts of the Shiveluch volcano (Kamchatka) (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.    Annotation
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.
Om Kamtjatkas vulkaner og Gejserdalen (2012)
Girina O.A. Om Kamtjatkas vulkaner og Gejserdalen // Geografisk orientering. 2012. № 2. P. 470-475.
On Deep Structure, Properties of the Upper Mantle, and Volcanism of the Kuril-Kamchatka Island Arc According to Seismic Data (1968)
Fedotov S.A. On Deep Structure, Properties of the Upper Mantle, and Volcanism of the Kuril-Kamchatka Island Arc According to Seismic Data / The Crust and Upper Mantle of the Pacific Area. Washington, DC: American Geophysical Union. Washington, DC: American Geophysical Union. 1968. Vol. 12. P. 131-139. doi:10.1029/GM012p0131.    Annotation
The results of detailed seismic investigations during the period 1961 to 1964 are described. Accurate data of focus location for Kamchatka and the Commander Islands are cited. The majority of earthquakes are located in the Pacific focal zone and the others are found in such remarkable tectonic regions as the east Kamchatka ranges, the continental slope of the Commander Islands, etc. The focal zone seismic activity decreases with increasing depth. The seismic activity at a depth of 250 km is 100 times less than the activity at a depth of 0–20 km. Kamchatka earthquake locations in relation to the Kuril-Kamchatka Island arc and deep water trench are approximately the same as those of the south Kuril Island earthquakes. The Kamchatka active volcano belt coincides with the region of earthquakes having focal depths of 100–200 km, especially between 125 and 175 km. S-wave screening in the magma chambers under the volcanoes is observed. The Avacha volcanic cluster magma chamber at a depth of 20–80 km has the form of a column, 25 km in diameter. P-wave velocity in the upper mantle under the Pacific Ocean and between the Aleutian trench and the Kuril-Kamchatka trench is about 8.2 km/sec, and under Kamchatka 7.7 km/sec. Local velocity decreases to basaltic range (Vp = 72 km/sec) in the upper mantle at a depth near 70 km under the east Kamchatka active volcano belt.
On Precursor of Kamchatkan Volcanoes Eruptions Based on Data from Satellite Monitoring (2012)
Girina O.A. On Precursor of Kamchatkan Volcanoes Eruptions Based on Data from Satellite Monitoring // Journal of Volcanology and Seismology. 2012. Vol. 6. № 3. P. 142-149. doi: 10.1134/S0742046312030049.    Annotation
Kamchatka is one of the most active volcanic regions on the planet. Large explosive volcanic eruptions, in which the ash elevates up to 8–15 km above sea level, occur here every 1.5 years. Study of eruptions precursors in order to reduce a volcanic risk for the population is an urgent problem of Volcanology. The available precursor of strong explosive eruptions of volcanoes, identified from satellite data (thermal anomaly), as well as examples of successful prediction of eruptions using this precursor, are represented in this paper.
On Some Features Peculiar to the September 22, 2005 Eruption of Young Shiveluch Volcano, Kamchatka (2014)
Girina O.A., Nuzhdaev A.A. On Some Features Peculiar to the September 22, 2005 Eruption of Young Shiveluch Volcano, Kamchatka // Journal of Volcanology and Seismology. 2014. Vol. 8. № 4. P. 218-227. doi: 10.1134/S0742046314040034.    Annotation
An explosive eruption of Young Shiveluch Volcano occurred on September 22, 2005, discharging a pyroclastic flow about 20 km long in the Baidarnaya River valley and an ashfall in the area of the Northern group of volcanoes.
On a Possibility of Heat Utilization of the Avachinsky Volcanic Chamber (1976)
Fedotov S.A., Balesta S.T., Droznin V.A., Masurenkov Yu.P., Sugrobov V.M. On a Possibility of Heat Utilization of the Avachinsky Volcanic Chamber // Proceedings Second United Nations Symposium on the Development and Use of Geothermal Resources. 1976. Vol. 1. P. 363-369.    Annotation
The sources of geothermal energy of Kamchatka are hydrothermal systems, local blocks of high heated rocks, and peripheral magma chambers of active volcanoes in particular. According to gravimetric, magnetic and seismic data, under the Avachinsky volcano there exists an anomalous zone which is suspected to be a peripheral magma chamber. It is localized at the boundary of the Upper Cretaceous basement and an overlying volcanogenous stratum at a depth of 1.5 km from sea level. Its geophysical data are as follows: the radius is 5.2±0.9 km; the density of rocks is 2.85 to 3.15 g/cm3, the velocity of longitudinal waves is 2200 m/sec, the viscosity of rocks is 105 to 108 poise. The temperature distribution in the near-chamber zone was calculated by clcctrointegrator at 0°C at the Earth's surface and 1000°C at the chamber surface for stationary and non-stationary (the period of 20 000 years) heating. Heat extraction may be possible if a system of artificial jointing iscreated. The capacity of a thermal reservoir with a volume of one cubic km at a depth of 5 km and a distance of 6 km from the volcano would be 2 x Ю14 kcal, extractable under non-stationary conditions, which could provide the work of power stations with a total capacity of 250 MW for a period of 100 years.
On deep structure properties of the upper mantle and volcanism of the Kuril Island arc (1966)
Fedotov S.A. On deep structure properties of the upper mantle and volcanism of the Kuril Island arc // Abstracts of papers related with geophysics: XI Pacific Science Congress: Proceedings. Tokyo. 1966. Vol. 3. P. 37
On probability of catastrophic explosive eruptions in the Kurile - Kamchatka volcanic area in future (1988)
Melekestsev I.V. On probability of catastrophic explosive eruptions in the Kurile - Kamchatka volcanic area in future // Kagoshima International Conference on Volcanoes. Abstracts. Kagoshima: 1988. P. 382
On some theoretical problems of Volcanology (1958)
Gorshkov G.S. On some theoretical problems of Volcanology // Bulletin of Volcanology. 1958. Vol. 19. № 1. P. 103-114. doi: 10.1007/BF02596600.
On the Magma Chambers beneath Klyuchevskoi Volcano, Kamchatka (2018)
Khubunaya S.A., Gontovaya L.I., Sobolev A.V., Khubunaya V.S. On the Magma Chambers beneath Klyuchevskoi Volcano, Kamchatka // Journal of Volcanology and Seismology. 2018. Vol. 12. № 2. P. 14-30. doi: 10.1134/80742046318020045.    Annotation
AAbstract—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.

Многочисленные вершинные и побочные извержения умереннокалиевых магнезиальных и высокоглиноземистых базальтов и андезибазальтов, их минералогические и геохимические особенности, состав природнозакаленных расплавных включений в оливинах шлаковых лапилли вулкана Ключевской свидетельствуют о наличии магматических очагов под вулканом. На это же указывает, дуализм в изменении содержаний СаО и А1203 в оливинах и клинопироксенах во время кристаллизации. Минералогические особенности высокоглиноземистых андезибазальтов, всех побочных извержений вулкана Ключевской свидетельствуют о внедрении магнезиальной магмы из глубинного очага в малоглубинную высокоглиноземистую камеру. Распределение некогерентных элементов в магнезиальных и глиноземистых породах вулкана указывает на их генезис из одного мантийного источника. Геохимические и минералогические данные находятся в хорошем соответствии с результатами геофизических исследований структуры и свойств литосферы под вулканом Ключевской.



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