Ishimaru Satoko, Arai Shoji Highly silicic glasses in peridotite xenoliths from Avacha volcano, Kamchatka arc; implications for melting and metasomatism within the sub-arc mantle // Lithos. 2009. Vol. 107. № 1–2. P. 93 - 106. doi: 10.1016/j.lithos.2008.07.005.
Silicate glasses in peridotite xenoliths from Avacha volcano have high SiO2 (up to 72 wt.) and highly SiO2-oversaturated characteristics; normative quartz content is up to 50 wt.. The glasses represent secondary melts solidified after interaction with mantle peridotite, i.e. crystallization of secondary orthopyroxene at the expense of olivine. We identified two kinds of silicate glasses in Avacha peridotites; one is higher in K2O and enriched in Rb, Ba, U, and Pb than the other. The glasses show basically similar chemical characteristics to the host basaltic andesite to andesite of the Avacha volcano. These chemical characteristics are inherited from slab-derived fluids/melts, which metasomatize the mantle wedge and induce partial melting. The differences of chemical features among the Avacha glasses are attributed to chemical difference of the slab-derived fluids/melts, possibly due to the difference of sediments/basalt ratio of the relevant slab. The low-degree partial melt of peridotite assisted by these fluids/melts, is primarily SiO2-oversaturated, and can conduct silicate metasomatism, evolving through interaction with surrounding mantle peridotite, i.e. formation of orthopyroxene at the expense of olivine. Highly silicic glasses, also reported from peridotite xenoliths from oceanic hotspots and continental rift zones, mostly result from assimilation of orthopyroxene by SiO2-undersaturated melts, which crystallize clinopyroxene and olivine. The glasses also show similar trace-element patterns to their host alkali basaltic magmas, as in the case of arc glasses/calc-alkali magmas. If the glasses in peridotite xenoliths are of silicate metasomatism origin, they are similar in chemistry to host magmas. Reaction between carbonatite melts and peridotites shows the same petrographical feature as that of SiO2-undersaturated silicate melts with peridotites. The glasses originated from carbonatite metasomatism, however, exhibit clearly different trace-element patterns from their host alkali basaltic magmas.
Ishimaru Satoko, Arai Shoji, Shukuno Hiroshi Metal-saturated peridotite in the mantle wedge inferred from metal-bearing peridotite xenoliths from Avacha volcano, Kamchatka // Earth and Planetary Science Letters. 2009. Vol. 284. № 3–4. P. 352 - 360. doi: 10.1016/j.epsl.2009.04.042.
Lithospheric mantle is inferred to be more oxidized than the asthenosphere, and mantle-wedge peridotites are characterized by high oxidation state relative to abyssal and continental peridotites due to addition of slab-derived fluids or melts. We found metals (native Ni, Fe silicides, native Fe and possible native Ti) from otherwise oxidized sub-arc mantle peridotite xenoliths from Avacha volcano, Kamchatka. This is contrary to the consensus and experimental results that the metals are stable only in deeper parts of the mantle (> 250 km). The metals from Avacha are different in chemistry and petrography from those in serpentinized peridotites. The Avacha metals are characteristically out of chemical equilibrium between individual grains as well as with surrounding peridotite minerals. This indicates their independent formation from different fluids. Some of the Avacha metals form inclusion trails with fluids and pyroxenes, leading to the inference that very local metal saturation resulted from rapid supply (‘flashing’) of reducing fluids from deeper levels. The fluids, possibly rich in H2, are formed by serpentinization at the cold base of the mantle wedge just above the slab, and they reduce overlying peridotites. We propose a metal-saturated peridotite layer, underlying the main oxidized portion, within the mantle wedge beneath the volcanic front to fore-arc region.
Ivanov B.V., Gorelchik V.I., Andreev V.N., Maksimov A.P., Stepanov V.V., Chirkov A.M. The 1972-1974 eruption of Klyuchevskoy volcano, Kamchatka // Bulletin of Volcanology. 1981. Vol. 44. № 1. P. 1-10. doi: 10.1007/BF02598184.
A new Klyuchevskoy volcano eruptive cycle encompasses terminal (March 30, 1972 to August 23, 1974) and lateral (August 23, 1974 to December, 1974) eruption stages. The terminal eruption stage resulted in lava flows and parasitic cones that formed on the south-western flank of the volcano.
Eruption products are moderately alkalic high-alumina olivine-bearing andesite-basalts. The terminal eruption stage was accompanied by volcanic earthquakes and volcanic tremor. The lateral eruption was accompanied by explosive earthquakes. Volcanic tremor was the most useful prognostic sign indicating the onset of the lateral eruption. Eruptive mechanisms are discussed.
Izbekov P., Eichelberger J., Belousova M., Ozerov A. Post-collapse trends at Bezymianny Volcano, Kamchatka, Russia and the May 6, 2006 eruption // AGU Fall Meeting 2006. Eos Trans. AGU, 87(52), Fall Meet. Suppl., Abstracts. 2006. P. V11B-0576.
Izbekov P., Eichelberger J., Ivanov B., Maximov A. Variations of Volcanic Glass Composition Show Possible Mixing Event at the Beginning of 1996 Eruption of Karymsky Volcano, Kamchatka, Russia // Trans. American Geophys. Union, Fall Meet. Suppl, Abstract . 1998. Vol. 79(45). P. V22B-10.
Izbekov P., Koloskov A., Maximov A., Khabunaya S. The 2012 Fissure Tolbachik Eruption: Preliminary Results of Petrological Investigation // Geophysical Research Abstracts. EGU General Assembly, Vienna, 2014. Vienna, Austria: EGU General Assembly 2014. 2014. Vol. 16. P. 11710
Izbekov Pavel E., Eichelberger John C., Patino Lina C., Vogel Thomas A., Ivanov Boris V. Calcic cores of plagioclase phenocrysts in andesite from Karymsky volcano: Evidence for rapid introduction by basaltic replenishment // Geology. 2002. Vol. 30. № 9. P. 799-802.
Calcic cores in plagioclase of Karymsky andesite of the 1996–2000 eruptive cycle texturally and compositionally (both trace and major elements) mimic the plagioclase phenocrysts of basalt erupted 6 km away at the onset of the cycle. These observations support the view that simultaneous eruption of andesite and basalt at Karymsky in the beginning of the cycle represents an example of replenishment and eruption triggering of an andesitic reservoir. Homogeneity of andesitic output occurred within two months. This suggests to us that blending of injected basalt into reservoir magma was thorough and rapid.
Ji Lingyun, Lu Zhong, Dzurisin Daniel, Senyukov Sergey Pre-eruption deformation caused by dike intrusion beneath Kizimen volcano, Kamchatka, Russia, observed by InSAR // Journal of Volcanology and Geothermal Research. 2013. Vol. 256. P. 87 - 95. doi: 10.1016/j.jvolgeores.2013.02.011.
Abstract Interferometric synthetic aperture radar (InSAR) images reveal a pre-eruption deformation signal at Kizimen volcano, Kamchatka, Russia, where an ongoing eruption began in mid-November, 2010. The previous eruption of this basaltic andesite-to-dacite stratovolcano occurred in 1927–1928. InSAR images from both ascending and descending orbital passes of Envisat and ALOS PALSAR satellites show as much as 6 cm of line-of-sight shortening from September 2008 to September 2010 in a broad area centered at Kizimen. About 20 cm of opening of a nearly vertical dike provides an adequate fit to the surface deformation pattern. The model dike is approximately 14 km long, 10 km high, centered 13 km beneath Kizimen, and strikes NE–SW. Time-series analysis of multi-temporal interferograms indicates that (1) intrusion started sometime between late 2008 and July 2009, (2) continued at a nearly constant rate, and (3) resulted in a volume expansion of 3.2 × 107 m3 by September 2010, i.e., about two months before the onset of the 2010 eruption. Earthquakes located above the tip of the dike accompanied the intrusion. Eventually, magma pressure in the dike exceeded the confining strength of the host rock, triggering the 2010 eruption. Our results provide insight into the intrusion process that preceded an explosive eruption at a Pacific Rim stratovolcano following nearly a century of quiescence, and therefore have implications for monitoring and hazards assessment at similar volcanoes elsewhere.
Jiang Guoming, Zhao Dapeng, Zhang Guibin Seismic tomography of the Pacific slab edge under Kamchatka // Tectonophysics. 2009. Vol. 465. № 1–4. P. 190 - 203. doi: 10.1016/j.tecto.2008.11.019.
We determine a 3-D P-wave velocity structure of the mantle down to 700 km depth under the Kamchatka peninsula using 678 P-wave arrival times collected from digital seismograms of 75 teleseismic events recorded by 15 portable seismic stations and 1 permanent station in Kamchatka. The subducting Pacific slab is imaged clearly that is visible in the upper mantle and extends below the 660-km discontinuity under southern Kamchatka, while it shortens toward the north and terminates near the Aleutian–Kamchatka junction. Low-velocity anomalies are visible beneath northern Kamchatka and under the junction, which are interpreted as asthenospheric flow. A gap model without remnant slab fragment is proposed to interpret the main feature of high-V anomalies. Combining our tomographic results with other geological and geophysical evidences, we consider that the slab loss may be induced by the friction with surrounding asthenosphere as the Pacific plate rotated clockwise at about 30 Ma ago, and then it was enlarged by the slab-edge pinch-off by the asthenospheric flow and the presence of Meiji seamounts. As a result, the slab loss and the subducted Meiji seamounts have jointly caused the Pacific plate to subduct under Kamchatka with a lower dip angle near the junction, which made the Sheveluch and Klyuchevskoy volcanoes shift westward.
Kalacheva Elena, Taran Yuri, Kotenko Tatiana Geochemistry and solute fluxes of volcano-hydrothermal systems of Shiashkotan, Kuril Islands // Journal of Volcanology and Geothermal Research. 2015. Vol. 296. P. 40-54. doi:10.1016/j.jvolgeores.2015.03.010.
Shiashkotan Island belongs to the Northern Kuril island arc and consists of two joined volcanoes, Sinarka and
Kuntomintar, with about 18 km of distance between the summits. Both volcanoes are active, with historic
eruptions, and both emit fumarolic gases. Sinarka volcano is degassing through the extrusive domewith inaccessible
strong and hot (N400 °C) fumaroles. A large fumarolic field of the Kuntomintar volcano situated in a wide
eroded caldera-like crater hosts many fumarolic vents with temperatures from boiling point to 480 °C. Both
volcanoes are characterized by intense hydrothermal activity discharging acid SO4-Cl waters, which are drained
to the Sea of Okhotsk by streams. At least 4 groups of near-neutral Na-Mg-Ca-Cl-SO4 springs with temperatures in
the range of 50–80 °C are located at the sea level,within tide zones and discharge slightly altered diluted seawater.
Volcanic gas of Kuntomintar as well as all types of hydrothermal manifestations of both volcanoes were collected
and analyzed for major and trace elements and water isotopes. Volcanic gases are typical for arc volcanoes
with 3He/4He corrected for air contamination up to 6.4 Ra (Ra=1.4 ×10−6, the air ratio) and δ13C (CO2) within
−10‰to−8‰VPDB. Using a saturation indices approach it is shown that acid volcanic waters are formed at a
shallow level, whereas waters of the coastal springs are partially equilibrated with rocks at ~180 °C. Trace
element distribution and concentrations and the total REE depend on the water type, acidity and Al+Fe concentration.
The REE pattern for acidic waters is unusual but similar to that found in some acidic crater lake waters.
The total hydrothermal discharge of Cl and S from the island associated with volcanic activity is estimated at
ca. 20 t/d and 40 t/d, respectively, based on the measurements of flow rates of the draining streams and
their chemistry. The chemical erosion of the island by surface and thermal waters is estimated at 27 and 140
ton/km2/year, respectively, which is 2–3 times lower than chemical erosion of tropical volcanic islands.