Библиография
Вулкан:
Группировать:  
Выбрать:     Все     "     0     1     2     3     4     5     7     A     B     C     D     E     F     G     H     I     K     L     M     N     O     P     Q     R     S     T     U     V     W          А     Б     В     Г     Д     Е     Ж     З     И     К     Л     М     Н     О     П     Р     С     Т     У     Ф     Х     Ц     Ч     Ш     Щ     Э     Ю     Я     
Записей: 45
Страницы:  1 2 3 4 5
 A
A 210Pb–226Ra–230Th–238U study of Klyuchevskoy and Bezymianny volcanoes, Kamchatka (2006)
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. Vol. 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.
A 210Pb–226Ra–230Th–238U study of Klyuchevskoy and Bezymianny volcanoes, Kamchatka (2007)
Turner Simon, Sims Kenneth W.W., Reagan Mark, Cook Craig A 210Pb–226Ra–230Th–238U study of Klyuchevskoy and Bezymianny volcanoes, Kamchatka // Geochimica et Cosmochimica Acta. 2007. Vol. 71. № 19. P. 4771 - 4785. doi: 10.1016/j.gca.2007.08.006.
   Аннотация
Lavas from Klyuchevskoy and Bezymianny volcanoes, Kamchatka, appear to show a link between the extent of partial melting in their mantle source region and the subsequent degree of fractionation suffered by the magmas during passage through the crust. This fractionation may have occurred on timescales significantly less than 1000 years if observed 226Ra excesses largely reflect variable residual porosity in the source melting region. Unlike most arc lavas, those with the highest MgO contents and Ba/Th ratios have the lowest 226Ra excess. Forward models suggest that those portions of the source which had undergone the greatest addition of U by fluids from the subducting plate also underwent the greatest extents of partial melting at the highest residual porosity. At Kluchevskoy, a change from eruption of high-MgO to high-Al2O3 basaltic andesites around 1945 is reflected in an increase in size of 226Ra excess which seems to require a simultaneous decrease in residual porosity and suggests a rapid changes in the melting regime. The eruption of andesites at Bezyminanny, simultaneous with the eruption of basaltic andesites at Klyuchevskoy, further suggests that different degree melts produced at differing residual porosity can be formed and extracted from the melt region at the same time. Thus, the melting processes beneath Klyuchevskoy and Bezyminanny are demonstrably complex. They have clearly been influenced by both fluid addition from the subducting plate and extension and decompression beneath the Central Kamchatka Depression. Finally, the 210Pb data are, with one or two exceptions, in equilibrium with 226Ra, suggesting that there was restricted relative magma-gas movement in this highly productive magmatic system.
A Calcium-in-Olivine Geohygrometer and its Application to Subduction Zone Magmatism (2016)
Gavrilenko M., Herzberg C., Vidito C., Carr M., Tenner T., Ozerov A. A Calcium-in-Olivine Geohygrometer and its Application to Subduction Zone Magmatism // Journal of Petrology. 2016. Vol. 57. № 9. P. 1811-1832. doi:10.1093/petrology/egw062.
   Аннотация
High-precision electron microprobe analyses were obtained on olivine grains from Klyuchevskoy, Shiveluch and Gorely volcanoes in the Kamchatka Arc; Irazu, Platanar and Barva volcanoes of the Central American Arc; and mid-ocean ridge basalt (MORB) from the Siqueiros Transform. Calcium contents of these subduction zone olivines are lower than those for olivines from modern MORB, Archean komatiite and Hawaii. A role for magmatic H2O is likely for subduction zone olivines, and we have explored the suggestion of earlier workers that it has affected the partitioning of CaO between olivine and silicate melt. We provide a provisional calibration of DCaO Ol/L as a function of magmatic MgO and H2O, based on nominally anhydrous experiments and minimally degassed H2O contents of olivine-hosted melt inclusions. Application of our geohygrometer typically yields 3–4 wt % magmatic H2O at the Kamchatka and Central American arcs for olivines having 1000 ppm Ca, which agrees with H2O maxima from melt inclusion studies; Cerro Negro and Shiveluch volcanoes are exceptions, with about 6% H2O. High-precision electron microprobe analyses with 10–20 lm spatial resolution on some olivine grains from Klyuchevskoy and Shiveluch show a decrease in Ca content from the core centers to the rim contacts, and a sharp increase in Ca in olivine rims. We suggest that the zoning of Ca in olivine from subduction zone lavas may provide the first petrological record of temporal changes that occur during hydration of the mantle wedge and dehydration during ascent, and we predict olivine H2O contents that can be tested by secondary ionization mass spectrometry analysis.
A Model for Klyuchevskoy Volcano Activity from Geodelical and Seismological Data (1988)
Zharinov N.A., Fedotov S.A., Gorelchik V.I. A Model for Klyuchevskoy Volcano Activity from Geodelical and Seismological Data // Kagoshima International Conference on Volcanoes: Proceedings of the International Conference on Volcanoes, Japan, Kagoshima, 19-23 July 1988. Kagoshima: Kagoshima Prefectural Government. 1988. P. 71-74.
A New Cluster Regime Of Gas-Liquid Flow In Vertical Columns (Physical Modeling) (2009)
Ozerov A.Yu. A New Cluster Regime Of Gas-Liquid Flow In Vertical Columns (Physical Modeling) // Сборник тезисов Международной конференции «Потоки и Структуры в Жидкостях: Физика Геосфер». М.: ИПМех РАН. 2009. Vol. 1. P. 178-181.
A New Estimate of Gas Emissions from Ebeko Volcano, Kurile Islands (2016)
Melnikov Dmitry, Malik N., Kotenko T., Inguaggiato Salvatore, Zelenski M. A New Estimate of Gas Emissions from Ebeko Volcano, Kurile Islands // Goldschmidt Conference. 26 June - 1 July, Yokohama, Japan. 2016. P. 2047
   Аннотация
Concentrations and emission rates of major gas species were measured in August 2015 at Ebeko volcano, a quiescently degassing andesitic volcano on Paramushir Island, Northern Kuriles. Using mobile and scanning DOAS measurements we estimated SO 2 emission from the active crater of the volcano at 100 +36/-15 t/d. Based on the comparison of plume areas of individual fumaroles, ca. 90% of the total gas emission from Ebeko in 2015 was provided by a single powerful vent (" Active Funnel " fumarole) and the rest was shared among low-temperature fumaroles. At the time of measurements, gases from the main fumarole had temperature from 420 to 490 °C and composition close to the average arc gas [1], as shown in Table. Gas species CO2 SO2 H2S HCl H2O T, °C mmol/mol Main fumarole 27.9 23.5 6.1 5.6 936 420 Low-temp. jets 92.2 2.62 0.68 1.6 902 <120 Low-temperature fumaroles (<120 °C) emitted gas enriched in CO 2 (up to 28 mol%, 9.2 mol% on average). Such CO 2 enrichment together with depletion in HCl and sulfur species can be explained by scrubbing of soluble gas species by a well-developed hydrothermal system which discharges ultra-acid SO 4-Cl waters [2]. A weighted-average estimate of the total gas+vapor emission from the Ebeko summit provided 1470 t/d, which includes ~ 101 t/d SO2, ~ 110 t/d CO2, ~ 14 t/d H2S and HCl, and 1230 t/d of water vapour with > 50% of the magmatic component. The gas fluxes measured in August 2015 using DOAS fall into the range of previous measurements made from 1960 to 2012 that used direct methods [2] and correspond to the moderate degassing rate of the volcano.
A Physicochemical Model for Deep Degassing of Water-Rich Magma (2008)
Maksimov A.P. A Physicochemical Model for Deep Degassing of Water-Rich Magma // Journal of Volcanology and Seismology. 2008. Vol. 2. № 5. P. 356-363. doi: 10.1134/S0742046308050059.
   Аннотация
Two powerful eruptions of Quizapu vent on Cerro Azul Volcano, Chile are used as examples to discuss
the problem of effusive eruptions of magmas having high preeruptive volatile concentrations. A physicochemical
mechanism is proposed for magma degassing, with the volatiles being lost before coming to the surface.
The model is based on the interaction of magmas residing in chambers at different depths and on the difference
between the solubility of water in the melt and the water equilibrium concentration in a magma body
having a considerable vertical extent. The shallower chamber can accumulate the volatiles released from the
magma that is supplied from the deeper chamber. An explanation is provided of the dramatic differences in the
character of the 1846–1847 and 1932 eruptions, which had identical chemical–petrographic magma compositions.
A Proposal to Monitor Volcanic Activity in the Kurile Islands (2002)
Girina O.A., Rybin A.V., Kirianov V.Yu. A Proposal to Monitor Volcanic Activity in the Kurile Islands // Abstracts. 3rd Biennial Workshop on Subduction Processes emphasizing the Kurile-Kamchatka-Aleutian Arcs (JKASP-3). Fairbanks. June 2002. 2002. P. 120
A chronology of the Holocene eruptions from the northern Kamchatka volcanoes based on linking major C14-dated tephra sequences with the help of EMPA glass data (2012)
Ponomareva Vera A chronology of the Holocene eruptions from the northern Kamchatka volcanoes based on linking major C14-dated tephra sequences with the help of EMPA glass data // Quaternary International. 2012. Vol. 279–28. P. 383 doi: 10.1016/j.quaint.2012.08.1191.
   Аннотация
Volcanic eruptions from Kamchatka have deposited many unique tephra layers over a large region within the North Pacific, providing important isochrons between key sites such as marine ODP core 883 (Pacific Ocean, Detroit Seamount) and Elgygytgyn Lake (Chukotka, eastern Siberia). Here we present a compilation of C14 dates on major Holocene tephras from the volcanically highly active region, based on decades of detailed stratigraphical fieldwork on Shiveluch, Kliuchevskoy, and other volcanoes.The 12-m thick tephra sequence at the Kliuchevskoy slope has been continuously accumulating during the last ∼11 ka. It contains over 200 visible individual tephra layers and no datable organic material. The section is dominated by dark-gray mafic cinders related to Kliuchevskoy activity. In addition, it contains 30 light-colored thin layers of silicic tephra from distant volcanoes including 11 layers from Shiveluch volcano located only 65 km to the north. We have used EMPA glass analysis to correlate most of the marker tephra layers to their source eruptions dated earlier by C14 (Braitseva et al., 1997; Ponomareva et al., 2007), and in this way linked Kliuchevskoy tephra sequence to sequences at other volcanoes including Shiveluch. The C14 dates and tephras from the northern Kamchatka are then combined into a single Bayesian framework taking into account stratigraphical ordering within and between the sites. This approach has allowed us to enhance the reliability and precision of the estimated ages for the eruptions. Age-depth models are constructed to analyse changes in deposition rates and volcanic activity throughout the Holocene. This detailed chronology of the eruptions serves as a basis for understanding temporal patterns in the eruption sequence and geochemical variations of magmas. This research could prove important for the long-term forecast of eruptions and volcanic hazards.
A dangling slab, amplified arc volcanism, mantle flow, and seismic anisotropy in the Kamchatka plate corner (2002)
Park J., Levin V., Brandon M., Lees J., Peyton V., Gordeev E., Ozerov A. A dangling slab, amplified arc volcanism, mantle flow, and seismic anisotropy in the Kamchatka plate corner / Plate Boundary Zones. AGU Geodynamics Series. 2002. Vol. 30. P. 295-324.