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 E
Estimation of the sulfur dioxide emission by Kamchatka volcanoes using differential optical absorption spectroscopy (2014)
Melnikov D.V., Ushakov S.V., Galle B. Estimation of the sulfur dioxide emission by Kamchatka volcanoes using differential optical absorption spectroscopy // 8-th Biennial Workshop on Japan-Kamchatka-Alaska Subduction Processes, JKASP 2014. 22-26 September, 2014, Sapporo, Japan. 2014.    Аннотация
During the 2012-2013 we have measured SO2 on Kamchatka volcanoes (Gorely, Mutnovsky, Kizimen, Tolbachik, Karymsky, Avachinsky) using DOAS (differential optical absorption spectroscopy). Mobile-DOAS, on a base of USB2000+, has been used as an instrument. The goal of this work was to estimate SO2 emission by Kamchatka volcanoes with the different types of activity. Mutnovsky and Avachinsky during the measurements period passively degassed with SO2 emission ~ 480 t/d and 210 t/d, respectively. Gorely volcano was very active, with intensive vapor-gas activity with gas discharge rate 800-1200 t/d. During the measurements at Karymsky volcano there were relatively weak explosive events (ash plum rose up to 0.5 km above the crater) with 5-10 minutes periodicity. For this time, SO2 discharge rate was ~350-400 t/d. Due to the remoteness and difficulties for accessibility of Kizimen volcano, the measurements were done only once – on October 15th, 2012. 5 traverses have been done above the gas plume. SO2 emission was ~ 700 t/d. On Tolbachik fissure eruption we have measured SO2 emission repeatedly from January until August 2013. The intensive effusion of the lava flows (basaltic andesite by composition) and frequent explosions in the crater of the cinder cone were characteristic features of this eruption. The measured gas emission was from ~1500-2200 t/d in January until 600-800 t/d in August 2013. All measurements were made not permanently, but to the extent possible. Therefore, it is difficult to make detailed conclusions on the SO2 emission on these volcanoes. Nevertheless, this research may become a starting point for the development of the system of the constant monitoring of volcanic gases emission by the active volcanoes of Kamchatka.

Estimation of the sulfur dioxide emission by Kamchatka volcanoes using differential optical absorption spectroscopy.
Evolution Stages and Petrology of the Kekuknai Volcanic Massif as Reflecting the Magmatismin Backarc Zone of Kuril-Kamchatka Island Arc System. Part 1. Geological Position and Geochemistry of Volcanic Rocks (2011)
Koloskov A.V., Flerov G.B., Perepelov A.B., Melekestsev I.V., Puzankov M.Yu., Filosofova T.M. Evolution Stages and Petrology of the Kekuknai Volcanic Massif as Reflecting the Magmatismin Backarc Zone of Kuril-Kamchatka Island Arc System. Part 1. Geological Position and Geochemistry of Volcanic Rocks // Journal of Volcanology and Seismology. 2011. V. 5. № 5. P. 312-334. doi: 10.1134/S074204631104004X.    Аннотация
The evolution of the Quaternary Kekuknai volcanic massif (the western flank of the Sredinnyi Range in Kamchatka) has been subdivided into five stages: (I) the pre-caldera trachybasalt- basaltic andes- ite, (2) the extrusive trachyandesite-trachydacite, (3) the early trachybasalt, (4) the middle hawaiite- mugearite (with occasional occurrences of basaltic andesites), and (5) the late trachybasalt-hawaiite- mugearite (with occasional andesites) of areal volcanism. On the basis of petrologic data we identified the island arc and the intraplate geochemical types of rocks in the massif. The leading part in petrogenesis was played by dynamics of the fluid phase with a subordinated role of fractional crystallization and hybridism. Successive saturation of rocks with the fluid phase in the course of melt evolution stopped at the time of caldera generation when most fluid mobile elements and silica had been extracted. The geological and petrologic data attest to the formation of the massif in the environment of a backarc volcanic basin during the beginning of rifting with active participation of mantle plume components.

Выделено пять стадий эволюции четвертичного Кекукнайского вулканического массива (западный фланг Срединного хребта Камчатки): 1) докальдерная трахибазальтовая-андезибазальтовая, 2) экструзивная трахиандезит-трахидацитовая, 3) ранняя трахибазальтовая, 4) средняя гавайит-муджиеритовая (с единичными проявлениями андезибазальтов) и 5) поздняя трахибазальт-гавайит-муджиеритовая (с единичными проявлениями андезитов) - ареального вулканизма. По петрологическим данным среди пород массива выделены островодужный и внутриплитный геохимические типы. Ведущую роль в пет-рогенезисе играла динамика флюидной фазы при подчиненной роли процессов фракционной кристаллизации и гибридизма. Последовательное насыщение пород флюидной фазой в ходе эволюции расплавов было прервано в период кальдерообразования, когда осуществилась экстракция большей части флюидомобильных элементов и кремнезема. Геологические и петрологические материалы свидетельствуют о том, что формирование массива произошло в обстановке задугового вулканического бассейна в условиях начавшегося рифтогенеза, при активном участии компонентов мантийного плюма.
http://repo.kscnet.ru/883/ [связанный ресурс]
Evolution and genesis of volcanic rocks from Mutnovsky Volcano, Kamchatka (2014)
Simon A., Yogodzinski G.M., Robertson K., Smith E., Selyangin O., Kiryukhin A., Mulcahy S.R., Walker J.D. Evolution and genesis of volcanic rocks from Mutnovsky Volcano, Kamchatka // Journal of Volcanology and Geothermal Research. 2014. V. 286. P. 116 - 137. doi: 10.1016/j.jvolgeores.2014.09.003.    Аннотация
This study presents new geochemical data for Mutnovsky Volcano, located on the volcanic front of the southern portion of the Kamchatka arc. Field relationships show that Mutnovsky Volcano is comprised of four distinct stratocones, which have grown over that past 80 ka. The youngest center, Mutnovsky IV, has produced basalts and basaltic andesites only. The three older centers (Mutnovsky I, II, III) are dominated by basalt and basaltic andesite (60–80 by volume), but each has also produced small volumes of andesite and dacite. Across centers of all ages, Mutnovsky lavas define a tholeiitic igneous series, from 48–70 SiO2. Basalts and basaltic andesites have relatively low K2O and Na2O, and high FeO* and Al2O3 compared to volcanic rocks throughout Kamchatka. The mafic lavas are also depleted in the light rare earth elements (REEs), with chondrite-normalized La/Sm < 1.0. Andesites have generally higher REE abundances and are more enriched in light REEs, some showing negative Eu anomalies. All samples are depleted in field strength elements (HFSEs) relative to similarly incompatible REEs (e.g., low La/Ta, Nd/Hf compared to MORB), similar to island arc volcanic rocks worldwide. Radiogenic isotope ratios (Sr, Nd, Pb, Hf) are similar for samples from all four eruptive centers, and indicate that all samples were produced by melting of a similar source mixture. No clear age-progressive changes are evident in the compositions of Mutnovsky lavas. Mass balance and assimilation-fractional crystallization (AFC) modeling of major and rare earth elements (REEs) indicate that basaltic andesites were produced by FC of plagioclase, clinopyroxene and olivine from a parental basalt, combined with assimilation of a melt composition similar to dacite lavas present at Mutnovsky. This modeling also indicates that andesites were produced by FC of plagioclase from basaltic andesite, combined with assimilation of dacite. Dacites erupted from Mutnovsky I and II have low abundances of REEs, and do not appear to be related to mafic magmas by FC or AFC processes. These dacites are modeled as the products of dehydration partial melting at mid-crustal levels of a garnet-free, amphibole-bearing basaltic rock, which itself formed in the mid-crust by emplacement of magma that originated from the same source as all Mutnovsky magmas. Lead isotope data indicate that subducted sediment is likely present in the source beneath Mutnovsky and most Kamchatka volcanoes, but uniformly radiogenic Hf and Nd in mafic samples (εNd = 8.7–9.3, εHf = 15.4–15.9), and significant variation in trace element ratios at nearly constant εNd and εHf, indicate that sediment plays a minor roll in controlling subduction trace element patterns in Mutnovsky lavas. Mafic lavas with Ba/Th > 450 require an aqueous fluid source component from subducting oceanic crust, but mixing patterns in isotope versus trace element ratio plots for Hf and the REEs (εNd and εHf vs. ratios with Ce, Nd and Hf) demonstrate that a source component with radiogenic Nd and Hf, and fractionated (arc-type) trace element ratios must be present in the source of Mutnovsky lavas. This source component, which is interpreted to be a partial melt of subducted basalt in the eclogite facies (eclogite melt source component), appears to be present in the source of all Kamchatka volcanoes. Cross-arc geochemical patterns at Mutnovsky and in other arc systems (Isu-Bonin, Tonga-Kermadec) suggest that the aqueous fluid component diminishes and the eclogite melt component is increased from volcanoes at the arc front compared to those in rear-arc positions.
Evolution of Quaternary Volcanism and Tectonics in the Western Part of the Pacific Ring (1972)
Erlich E.N., Melekestsev I.V. Evolution of Quaternary Volcanism and Tectonics in the Western Part of the Pacific Ring // Pacific Geology. 1972. № 4. P. 1-22.
Evolution of Recent Volcanism (1979)
Erlich E.N., Melekestsev I.V., Braitseva O.A. Evolution of Recent Volcanism // Bulletin of Volcanology. 1979. V. 42. № 1-4. P. 93-112. doi: 10.1007/BF02597042.
Explosive Eruptions of Kamchatkan Volcanoes in 2010 (2011)
Girina O.A., Manevich A.G., Ushakov S.V., Nuzhdaev A.A., Melnikov D.V., Konovalova O.A., Demyanchuk Yu.V. Explosive Eruptions of Kamchatkan Volcanoes in 2010 // Abstract. EGU General Assembly. April 3-8. Vienna. 2011. EGU2011-2342 (XY 513). 2011. V. 13.
Explosive Eruptions of Kamchatkan Volcanoes in 2012 and Danger to Aviation (2013)
Girina O.A., Manevich A.G., Melnikov D.V., Nuzhdaev A.A., Demyanchuk Yu.V., Petrova E. Explosive Eruptions of Kamchatkan Volcanoes in 2012 and Danger to Aviation // EGU General Assembly 2013. Geophysical Research Abstracts. Vienna, Austria: 2013. V. V15. № 6760-1.
Explosive Eruptions of Kamchatkan Volcanoes in 2013 and Danger to Aviation (2014)
Girina O.A., Manevich A.G., Melnikov D.V., Demyanchuk Yu.V., Petrova E. Explosive Eruptions of Kamchatkan Volcanoes in 2013 and Danger to Aviation // EGU2014. Abstracts. Vienna, Austria: 2014. P. 1468
Explosive basaltic volcanism of the Chikurachki Volcano (Kurile arc, Russia): Insights on pre-eruptive magmatic conditions and volatile budget revealed from phenocryst-hosted melt inclusions and groundmass glasses (2005)
Gurenko A.A., Belousov A.B., Trumbull R.B., Sobolev A.V. Explosive basaltic volcanism of the Chikurachki Volcano (Kurile arc, Russia): Insights on pre-eruptive magmatic conditions and volatile budget revealed from phenocryst-hosted melt inclusions and groundmass glasses // Journal of Volcanology and Geothermal Research. 2005. V. 147. № 3-4. P. 203-232. doi:10.1016/j.jvolgeores.2005.04.002.
 F
Fe-Mg и микроэлементная зональность в камчатских оливинах (2016)
Гордейчик Б.Н., Чурикова Т.Г., Кронц А., Симакин А.Г., Вёрнер Г. Fe-Mg и микроэлементная зональность в камчатских оливинах // Вулканизм, биосфера и экологические проблемы. Восьмая международная научная конференция. Сборник материалов. Туапсе, 1-6 октября 2016 г. Майкоп-Туапсе: Адыгейский государственный университет. 2016. С. 27-29.
First Historical Eruption of Kambalny Volcano (2018)
Gordeev E.I., Girina O.A., Gorbach N.V., Manevich A.G., Melnikov D.V., Anikin L.P., Manevich T.M, Dubrovskaya I. K., Chirkov S.A., Kartashova E.V. First Historical Eruption of Kambalny Volcano // Doklady Earth Sciences. 2018. V. 482. P. 1257-1259. doi: 10.1134/S1028334X18100045.    Аннотация
The first historical eruption of Kambalny volcano began on March 24, 2017 with the powerful ash emission from the summit crater reaching as high as 6 km above sea level. The explosive activity continued without interruption from March 24 to March 30. The most powerful ash emission was registered on March 25–26, when the ash plume drifted several thousand kilometers SW, S, and SE from the volcano. On April 2 and April 9, after several calm days, powerful ash explosions occurred generating ash plumes up to 7 km high. The area of the land and sea over which the ash plume drifted during the day of March 25, was 650000 km2; the area of the ash accumulation on the land that was formed from March 24 to April 9, exceeded 1500 km2. These parameters were measured using the satellite-based data in the VolSatView information system. Domination of the silty fraction and the presence of secondary minerals (pyrite, gypsum, sulfur, and others) in the ash point to the phreatic character of the volcanic eruption.
First data on composition of the volcanic rocks of the IVS 50th anniversary Fissure Tolbachik eruption (Kamchatka) (2013)
Volynets A.O., Melnikov D.V., Yakushev A.I. First data on composition of the volcanic rocks of the IVS 50th anniversary Fissure Tolbachik eruption (Kamchatka) // Doklady Earth Sciences. 2013. V. 452. № 1. P. 953-957. doi:10.1134/S1028334X13090201.    Аннотация
First data on major, minor and trace element (XRF. ICP-MS) concentrations in the volcanic rocks of the IVS 50th anniversary Fissure Tolbachik eruption are reported for the period from 27.11.2012 to 25.01.2013; scheme of lava flows distribution by March 2013 is made. The volcanic rocks of the new eruption are substantially different from the other studied volcanic rocks of Tolbachinsky Dol by their higher alkalis and incompatible elements content. The rocks of the first three days of eruption (Menyailov Vent) have higher silica and alkalis content than all previously reported volcanic rocks of Tolbachinsky Dol. Volcanic rocks of the Naboko Vent, at silica content similar to high-Al basalts of Tolbachinsky Dol, have different concentrations of trace elements and some major elements (K2O, CaO, TiO2, P2O5). REE and other incompatible element concentrations in the rocks of the Menyailov Vent are higher than in the rocks of the Naboko Vent at the same element ratios. The differences of the volcanic rocks of the two vents of the new eruption may be caused by the fact that the erupted lavas came from the different levels of the same magma chamber.
http://repo.kscnet.ru/1103/ [связанный ресурс]
First data on magma ascent and residence times retrieved from Fe-Mg and trace element zonation in olivine phenocrysts from Kamchatka basalts (2016)
Gordeychik Boris, Churikova Tatiana, Kronz Andreas, Simakin Alexander, Wörner Gerhard First data on magma ascent and residence times retrieved from Fe-Mg and trace element zonation in olivine phenocrysts from Kamchatka basalts // Geophysical Research Abstracts. 2016. V. 18. P. EGU2016-12839.    Аннотация
Compositional zonation in olivine phenocrysts and diffusion modelling have been used in the last ten years to estimate magma residence times and the duration of magma ascent. The fundamental assumption is that mixing with newly injected magma into a reservoir triggers diffusional exchange between mafic olivine crystals and more evolved magma and that this magma mixing eventually triggers eruption. If depth of mixing is known, this translates to ascent rates of magmas to the surface. We applied this approach to a series of different arc basalt lavas from Kamchatka to constrain the rates of magma ascent and magma resident in what is one of the most active subduction zones in the world that is also dominated by an abundance of unusually mafic magmas. Our sample collection cover the principal modes of arc magmatism in Kamchatka: from different volcanic complexes (stratovolcano, dikes, summit eruptions, monogenetic cones), of different age (from Late-Pleistocene to Holocene and recent eruptions), from different magmatic regimes (long-lived volcanoes vs. monogenetic eruptions) and different major element composition (from basalt to basaltic andesite of different geochemical character including LILE enrichments). We analyzed and modelled zonation profiles for a range of elements with different diffusivities (e.g. Mg-Fe, Ca, Ni, Mn, Cr) to assess the role of variable diffusivities as a function of major and trace elements in the olivines from different P-T conditions. First data were obtained on samples from the Klyuchevskoy, Shiveluch and Tolbachik, including recent most eruption in 2012/2013. These data show that for some samples the zonation patterns are much more complex than is usually observed: high-Mg olivines at different volcanoes have very different zonation patterns, including normally, reversely zoned grains or even show highly complex repetitive zonation that indicate large compositional changes in the surrounding magma at very short time scales (years). Thus in some Kamchatka basalts, we observe unusual Mg-Fe zonations that are linked to complex mixing, possibly resorption and subsequent crystal growth processes that are generally not preserved due to fast diffusion of Mg-Fe. Based on a first assessment of our measured profiles, the values for diffusion times in Fo-rich olivines (88 to 92% Fo) vary from only a few months to years and thus magma ascent from deep magma sources must have been fast.
First data on the volatile fluxes from passively degassing volcanoes of the Kuril Island arc (2017)
Melnikov Dmitry, Malik Nataliya, Chaplygin Ilya, Zelenski Mikhail First data on the volatile fluxes from passively degassing volcanoes of the Kuril Island arc // EGU General Assembly 2017. 2017. V. 19.
Formation of partially submerged tuff ring during the 1996 sublacustrine surtseyan eruption in Karymskoye lake, Kamchatka,Russia (2000)
Belousov Alexander, Belousova Marina Formation of partially submerged tuff ring during the 1996 sublacustrine surtseyan eruption in Karymskoye lake, Kamchatka,Russia // Terra Nostra. International Maar Conference: GeoForschungs Zentrum Potsdam. 2000. V. 6. P. 42-52.
 G
Gas composition in Mutnovsky geothermal field: Role of meteoric water (2011)
Maximov A.P., Firstov P.P., Chernev I.I., Shapar V.N. Gas composition in Mutnovsky geothermal field: Role of meteoric water // 11th Gas Workshop. 1-10 September 2011, Kamchatka, Russia. 2011. P. 31
Gas Emissions From Volcanoes of the Kuril Island Arc (NW Pacific): Geochemistry and Fluxes (2018)
Taran Yuri, Zelenski Mikhail, Chaplygin Ilya, Malik Natalia, Campion Robin, Inguaggiato Salvatore, Pokrovsky Boris, Kalacheva Elena, Melnikov Dmitry, Kazahaya Ryunosuke, Fischer Tobias Gas Emissions From Volcanoes of the Kuril Island Arc (NW Pacific): Geochemistry and Fluxes // Geochemistry, Geophysics, Geosystems. 2018. V. 19. V. 6. P. 1859-1880. doi: 10.1029/2018GC007477.    Аннотация
The Kuril Island arc extending for about 1,200 km from Kamchatka Peninsula to Hokkaido Island is a typical active subduction zone with ∼40 historically active subaerial volcanoes, some of which are persistently degassing. Seven Kurilian volcanoes (Ebeko, Sinarka, Kuntomintar, Chirinkotan, Pallas, Berg, and Kudryavy) on six islands (Paramushir, Shiashkotan, Chirinkotan, Ketoy, Urup, and Iturup) emit into the atmosphere > 90% of the total fumarolic gas of the arc. During the field campaigns in 2015–2017 direct sampling of fumaroles, MultiGas measurements of the fumarolic plumes and DOAS remote determinations of the SO2 flux were conducted on these volcanoes. Maximal temperatures of the fumaroles in 2015–2016 were 510°C (Ebeko), 440°C (Sinarka), 260°C (Kuntomintar), 720°C (Pallas), and 820°C (Kudryavy). The total SO2 flux (in metric tons per day) from fumarolic fields of the studied volcanoes was measured as ∼1,800 ± 300 t/d, and the CO2 flux is estimated as 1,250 ± 400 t/d. Geochemical characteristics of the sampled gases include δD and δ18O of fumarolic condensates, δ13C of CO2, δ34S of the total sulfur, ratios 3He/4He and 40Ar/36Ar, concentrations of the major gas species, and trace elements in the volcanic gas condensates. The mole ratios C/S are generally <1. All volcanoes of the arc, except the southernmost Mendeleev and Golovnin volcanoes on Kunashir Island, emit gases with 3He/4He values of >7RA (where RA is the atmospheric 3He/4He). The highest 3He/4He ratios of 8.3RA were measured in fumaroles of the Pallas volcano (Ketoy Island) in the middle of the arc.
Generation of calc-alkaline andesite of the Tatun volcanic group (Taiwan) within an extensional environment by crystal fractionation (2014)
Shellnutt J. Gregory, Belousov Alexander, Belousova Marina, Wang Kuo-Lung, Zellmer Georg F. Generation of calc-alkaline andesite of the Tatun volcanic group (Taiwan) within an extensional environment by crystal fractionation // International Geology Review. 2014. V. 56. № 9. P. 1156-1171. doi:10.1080/00206814.2014.921865.
Generation of pyroclastic flows by explosive interaction of lava flows with ice/water-saturated substrate (2011)
Belousov Alexander, Behncke Boris, Belousova Marina Generation of pyroclastic flows by explosive interaction of lava flows with ice/water-saturated substrate // Journal of Volcanology and Geothermal Research. 2011. V. 202. № 1-2. P. 60-72. doi:10.1016/j.jvolgeores.2011.01.004.
Genesis of Quaternary volcanism of high-Mg andesitic rocks in the northeast Kamchatka Peninsula (2016)
Nishizawa Tatsuji, Nakamura Hitomi, Churikova T., Gordeychik B., Ishizuka Osamu, Iwamori Hikaru Genesis of Quaternary volcanism of high-Mg andesitic rocks in the northeast Kamchatka Peninsula // Japan Geoscience Union Meeting. 22-26 May 2016, Makuhari, Messe. 2016. P. SVC48-02.    Аннотация
Arc magmatism is a product of subduction factory, involving thermal and chemical interactions
between a subducted slab as a material input and mantle wedge as a processing factory. In turn, the
compositions of arc magma provide invaluable information concerning the material input and the
interactions. The northeast Kamchatka Peninsula is an ideal field to examine such interactions and
relationships, being characterized by (1) subduction of the Emperor Seamount Chain (Davaille and
Lees, 2004), and (2) possible material and thermal interaction among the subducted slab, the
overlying mantle wedge and the sub-slab mantle via the edge of subducted Pacific slab (Portnyagin
and Manea, 2008). Within this area, a monogenetic volcanic group occurs along the east coast,
including high-Mg andesitic rocks and relatively primitive basalts (East Cones, EC (Fedorenko,
1969)). We have conducted geochemical studies of the EC lavas, with bulk rock major and trace
elements, and K-Ar and Ar-Ar ages, based on which a possible contribution of subducted seamounts
and its relation to the tectonic setting are discussed.
The elemental compositions indicate that the lavas from individual cones have distinct mantle
sources with different amounts and/or compositions of slab-derived fluids. Based on mass balance,
water content and melting phase relations, we estimate the melting P-T conditions to bet ~1200 ℃
at 1.5 GPa, while the slab surface temperature is 620 –730 ℃ (at 50-80 km depth). Compared with
the southern part of Kamchatka, the slab surface temperature beneath EC seems to be high due to the
thinner Pacific slab associated with the seamount chain and/or the plate rejuvenation from a mantle
plume impact (Davaille and Lees, 2004; Manea and Manea, 2007).
The K-Ar and Ar-Ar ages of the Middle Pleistocene are consistent with the tephrochronological
study (Uspensky and Shapiro, 1984) and the present tectonic setting after 2 Ma (Lander and Shapiro,
2007). The high-Mg andesite with the highest SiO2 content in the EC lavas shows the oldest age
(0.73 ±0.06 Ma) within not only EC but also the northeast part of Kamchatka (e.g., Churikova et
al., 2015, IAVCEI). On the other hand, the rest of EC lava samples show relatively younger ages to
0.18 ±0.07 Ma. These results suggest that the EC lavas including high-Mg andesite and basalt were
generated by mantle flux-melting induced by dehydration of a subducted seamount inheriting a local
thermal anomaly (Nishizawa et al., 2014, JpGU; 2015, JpGU).

島弧火成活動はサブダクションファクトリーの産物で, それは沈み込んだスラブ(物質のインプット)-マン
トルウェッジ(加工工場)間の熱的・物質的相互作用を含む. 島弧マグマの組成は, その物質インプットと相
互作用について非常に貴重な情報をもたらす. カムチャツカ半島北東部はそのような相互作用と関係性を調べ
るうえで理想的な場所である, それは次のような特徴を有する為だ(1)天皇海山列の沈み込み(Davaille and
Lees, 2004)(2)沈み込んだスラブ, マントルウェッジと太平洋スラブエッジにかけてのサブスラブマントル
との物質的・熱的相互作用の可能性(Portnyagin and Manea, 2008). この地域の東海岸沿いに, 高-Mg安山岩
と比較的初生的な玄武岩を産出する単成火山群が確認されている(East Cones, EC(Fedorenko, 1969)).
我々はこのEC溶岩について全岩主要-微量元素組成分析とK-Ar, Ar-Ar年代測定を含む地球化学的研究を行い,
沈み込んだ海山からの寄与の可能性とテクトニックセッティングとの関係について議論する.
EC溶岩の組成は, 火山ごとに独立したソースに由来しており, そのソースの違いはスラブ起源流体の量および
またはその組成の違いによることを示す. マスバランス, 含水量, 相関係に基づき, 我々は溶融温度-圧力条
件を推定した, 溶融温度・圧力~1200℃, 1.5 GPa, スラブ表面温度 620-730℃(深度50-80 km). カム
チャツカ南部に沈み込むスラブ表面温度と比較すると, EC直下のスラブ表面温度は高く, これは天皇海山列に
沿ったプレートの薄化およびまたは沈み込む直前のプルームからの熱的効果による若返り効果によるものと考
えられる(Davaille and Lees, 2004; Manea and Manea, 2007).
K-Ar, Ar-Ar年代測定値は中期更新世で, これはテフラ層序学からの推定年代と一致し(Uspensky and
Shapiro, 1984), 2Ma以降現在のテクトニックセッティングに変化したこととも矛盾しない(Lander and
Shapiro, 2007). 最もSiO2含有量が高い高Mg安山岩は最古の年代を示し(0.73 ±0.06 Ma), これはECのみな
らずカムチャツカ北東部においても最も古いとみられる(e.g., Churikova et al., 2015, IAVCEI). 一方他
のECはより若い年代を示す(~0.18 ±0.07 Ma). これらの結果は以下のことを示す: 高Mg安山岩, 玄武岩を
含むEC溶岩は沈み込んだ海山による局所的な温度異常がスラブ起源流体の脱水を強めそれによって生じたフ
ラックス溶融によりもたらされた(西澤他, 2014, JpGU; 2015, JpGU).





 

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