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 2006
Dirksen O., Humphreys M.C.S., Pletchov P., Melnik O., Demyanchuk Y., Sparks R.S.J., Mahony S. The 2001–2004 dome-forming eruption of Shiveluch volcano, Kamchatka: Observation, petrological investigation and numerical modelling // Journal of Volcanology and Geothermal Research. 2006. V. 155. № 3–4. P. 201 - 226. doi: 10.1016/j.jvolgeores.2006.03.029.    Аннотация
There have been three episodes of lava dome growth at Shiveluch volcano, Kamchatka since the Plinian explosive eruption in 1964. The episodes in 1980–1981, 1993–1995 and 2001–2004 have discharged at least 0.27 km3 of silicic andesite magma. A time-averaged mean extrusion rate of 0.2 m3/s is thus estimated for the last 40 years. Here the 2001–2004 activity is described and compared with the earlier episodes. The recent activity involved three pulses in extrusion rate and a transition to ongoing lava extrusion. Estimated magma temperatures are in the range 830 to 900 °C, with 850 °C as the best estimate, using the plagioclase−amphibole phenocryst assemblage and Fe−Ti oxides. Melt inclusions in amphibole and plagioclase have maximum water contents of 5.1 wt.%, implying a minimum pressure of ∼ 155 MPa for water-saturated conditions. The magma chamber depth is estimated to be about 5–6 km or more, a result consistent with geophysical data. The thicknesses of opx–mt–amph reaction rims on olivine xenocrysts are used to estimate the residence time of olivine crystals in the shallow chamber in the range 2 months to 4 years, suggesting replenishment of deeper magma into the shallow chamber contemporaneous with eruption. The absence of decompression-driven breakdown rims around amphiboles indicates ascent times of less than 7 days. Volcanological observations of the start of the 2001–2004 episode suggest approximately 16 days for the ascent time and a conduit equivalent to a cylinder of diameter approximately 53–71 m. Application of a conduit flow model indicates that the magma chamber was replenished during the 2001–2004 eruption, consistent with the results of olivine reaction rims, and that the chamber has an estimated volume of order 7 km3.
Gavrilenko M.G., Ozerov A.Yu., Kyle P.R., Eichelberger J.C. Petrological and Geochemical Characteristics of Magmatic Melts at Gorely Volcano, Kamchatka, Russia // AGU Fall Meeting 2006. Eos Trans. AGU, 87(52), Fall Meet. Suppl., Abstracts. 2006. P. V11A-0558.
Girina O.A., Gorbach N.V., Nuzhdaev A.A. Geological Effect of 2005 Eruptions of Sheveluch Volcano, Kamchatka, Russia // Abstracts. 5rd Biennial Workshop on Subduction Processes emphasizing the Japan-Kurile-Kamchatka-Aleutian Arcs (JKASP-5). 2006. P. 43
Girina O.A., Senyukov S.L., Neal C.A. Kamchatkan Volcanic Eruption Response Team (KVERT) Project in 2004-2006 // Abstracts. 5rd Biennial Workshop on Subduction Processes emphasizing the Japan-Kurile-Kamchatka-Aleutian Arcs (JKASP-5). 2006. P. 161-162. № P 618.
Girina O.A., Ushakov S.V., Senyukov S.L. Kamchatkan Volcanic Eruption Response Team (Project KVERT) // Abstracts for Fourth International Conference Cities on Volcanoes. IAVCEI. Quito-Ecuador. January 23-27. 2006. 2006. P. 150
Gordeev E.I., Girina O.A., Ushakov S.V., Senyukov S.L. Active volcanoes on Kamchatka, Russia // Abstracts for Fourth International Conference Cities on Volcanoes. IAVCEI. Quito-Ecuador. January 23-27. 2006. 2006. P. 22
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.
Pevzner M.M. Holocene volcanism of Northern Kamchatka: The spatiotemporal aspect // Doklady Earth Sciences. 2006. Т. 409. № 2. С. 884-887. doi: 10.1134/S1028334X06060109.
Ponomareva Vera V., Melekestsev Ivan V., Dirksen Oleg V. Sector collapses and large landslides on Late Pleistocene–Holocene volcanoes in Kamchatka, Russia // Journal of Volcanology and Geothermal Research. 2006. V. 158. № 1-2. P. 117-138. doi:10.1016/j.jvolgeores.2006.04.016.    Аннотация
On Kamchatka, detailed geologic and geomorphologic mapping of young volcanic terrains and observations on historical eruptions reveal that landslides of various scales, from small (0.001 km3) to catastrophic (up to 20–30 km3), are widespread. Moreover, these processes are among the most effective and most rapid geomorphic agents. Of 30 recently active Kamchatka volcanoes, at least 18 have experienced sector collapses, some of them repetitively. The largest sector collapses identified so far on Kamchatka volcanoes, with volumes of 20–30 km3 of resulting debris-avalanche deposits, occurred at Shiveluch and Avachinsky volcanoes in the Late Pleistocene. During the last 10,000 yr the most voluminous sector collapses have occurred on extinct Kamen' (4–6 km3) and active Kambalny (5–10 km3) volcanoes. The largest number of repetitive debris avalanches (> 10 during just the Holocene) has occurred at Shiveluch volcano. Landslides from the volcanoes cut by ring-faults of the large collapse calderas were ubiquitous. Large failures have happened on both mafic and silicic volcanoes, mostly related to volcanic activity. Orientation of collapse craters is controlled by local tectonic stress fields rather than regional fault systems.

Specific features of some debris avalanche deposits are toreva blocks — huge almost intact fragments of volcanic edifices involved in the failure; some have been erroneously mapped as individual volcanoes. One of the largest toreva blocks is Mt. Monastyr' — a ∼ 2 km3 piece of Avachinsky Somma involved in a major sector collapse 30–40 ka BP.

Long-term forecast of sector collapses on Kliuchevskoi, Koriaksky, Young Cone of Avachinsky and some other volcanoes highlights the importance of closer studies of their structure and stability.
Turner S.P., Sims K.W.W., Reagan M.K. A 210Pb–226Ra–230Th–238U study of Klyuchevskoy and Bezymianny volcanoes, Kamchatka // Geochimica et Cosmochimica Acta. 2006. V. 70. № 18, Su. P. A661 doi: 10.1016/j.gca.2006.06.1234.    Аннотация
Klyuchevskoy is one of the most active volcanoes on Earth, erupting lavas at a rate of ∼1 m3/s, equivalent to a 50 km length of mid-ocean ridge. Bezymianny is located 20 km south of the summit vent of Klyuchevskoy and has been erupting silicic andesites since its spectacular avalanche eruption in 1956. Major and trace element concentrations and long-lived radiogenic isotope data suggest that basalts and basaltic andesites from Klyuchevskoy and andesites from Bezymianny were derived by different degrees of partial melting of nearly identical mantle sources. Lavas with higher SiO2 concentrations represent the differentiation products of lower degrees of melting after the mantle was fluxed with a fluid derived almost entirely from subducted altered basaltic crust with little or no sediment contribution. The higher SiO2 concentrations for lavas derived from smaller degree melts suggest that they underwent more fractionation because of the loss of their higher water contents. High Th isotope compositions for all lavas from both volcanoes suggest that a significant time transpired between U addition by a slab-fluid and melting. If the excess 226Ra in the lavas is from the slab-fluid, then long term multistage fluxing before melting is required to maintain these 226Ra excesses. An alternative model attributes the excess Ra to melting caused by upwelling mantle in association with rifting of the central Kamchatka depression. The greater Ra excess for Klyuchevskoi’s basaltic andesites compared to its basalts is consistent with generation of the Ra excesses during decompression melting, and a less than few thousand year time frame of differentiation after melting. The lower Ra excesses for Bezymianny’s andesites compared to the more mafic lavas suggest a time frame of fractionation that is longer than this by several thousand years. When time since eruption is accounted for, all samples have (210Pb/226Ra) within 2σ analytical error of one, suggesting that significant long-term gas fluxing of 222Rn into or out of both magma systems has not occurred.



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