Записей: 2355
Bindeman I.N., Leonov V.L., Izbekov P.E., Ponomareva V.V., Watts K.E., Shipley N.K., Perepelov A.B., Bazanova L.I., Jicha B.R., Singer B.S., Schmitt A.K., Portnyagin M.V., Chen C.H. Large-volume silicic volcanism in Kamchatka: Ar–Ar and U–Pb ages, isotopic, and geochemical characteristics of major pre-Holocene caldera-forming eruptions // Journal of Volcanology and Geothermal Research. 2010. Vol. 189. № 1-2. P. 57-80. doi:10.1016/j.jvolgeores.2009.10.009.    Аннотация
The Kamchatka Peninsula in far eastern Russia represents the most volcanically active arc in the world in terms of magma production and the number of explosive eruptions. We investigate large-scale silicic volcanism in the past several million years and present new geochronologic results from major ignimbrite sheets exposed in Kamchatka. These ignimbrites are found in the vicinity of morphologically-preserved rims of partially eroded source calderas with diameters from ∼ 2 to ∼ 30 km and with estimated volumes of eruptions ranging from 10 to several hundred cubic kilometers of magma. We also identify and date two of the largest ignimbrites: Golygin Ignimbrite in southern Kamchatka (0.45 Ma), and Karymshina River Ignimbrites (1.78 Ma) in south-central Kamchatka. We present whole-rock geochemical analyses that can be used to correlate ignimbrites laterally. These large-volume ignimbrites sample a significant proportion of remelted Kamchatkan crust as constrained by the oxygen isotopes. Oxygen isotope analyses of minerals and matrix span a 3‰ range with a significant proportion of moderately low-δ18O values. This suggests that the source for these ignimbrites involved a hydrothermally-altered shallow crust, while participation of the Cretaceous siliceous basement is also evidenced by moderately elevated δ18O and Sr isotopes and xenocryst contamination in two volcanoes. The majority of dates obtained for caldera-forming eruptions coincide with glacial stages in accordance with the sediment record in the NW Pacific, suggesting an increase in explosive volcanic activity since the onset of the last glaciation 2.6 Ma. Rapid changes in ice volume during glacial times and the resulting fluctuation of glacial loading/unloading could have caused volatile saturation in shallow magma chambers and, in combination with availability of low-δ18O glacial meltwaters, increased the proportion of explosive vs effusive eruptions. The presented results provide new constraints on Pliocene–Pleistocene volcanic activity in Kamchatka, and thus constrain an important component of the Pacific Ring of Fire.
Blokh Yu. I., Bondarenko V. I., Dolgal’ A. S., Novikova P. N., Petrova V. V., Pilipenko O. V., Rashidov V. A., Trusov A. A. The Rikord Submarine Volcanic Massif, Kuril Island Arc // Journal of Volcanology and Seismology. 2018. Vol. 12. № 4. P. 252-267. doi:10.1134/S0742046318040024.    Аннотация
This paper reports a study of the Rikord volcanic massif. The massif consists of four volcanic edifices that coalesce in their bases, and is most likely Quaternary. The massif discharged basaltic and basaltic andesite lavas during its earlier life. The observed high natural remanent magnetization that was found in dredged rocks is due to high concentrations of single-domain and pseudo-single-domain grains of titanomagnetite and magnetite. We have identified the directions of the conduits and the presence of peripheral magma chambers. A 3D model has been developed for the central part of the Rikord volcanic massif; the model includes ten large disturbing magnetic blocks that are most likely cooled, nearly vertical, conduits.

Изучено строение подводного вулканического массива Рикорда, состоящего из четырех сливающихся по основанию вулканических построек, и имеющего, скорее всего, четвертичный возраст. На начальных этапах жизни вулканического массива изливались базальтовые и андезибазальтовые лавы. Высокие значения естественной остаточной намагниченности драгированных пород обусловлены большим содержанием однодоменных и псевдооднодоменных зерен титаномагнетита и магнетита. Установлены направления подводящих каналов и наличие периферических магматических очагов. Построена объемная модель центральной части вулканического массива Рикорда, в которой выделено десять крупных магнитовозмущающих блоков, которые, вероятнее всего, являются застывшими субвертикальными подводящими каналами.
Bogatikov O.A., Melekestsev I.V., Gurbanov A.G., Katov D.M., Puriga A.I. The Catastrophic Paleolahars of the Elbrus Volcano, Northern Caucasus // Doklady Earth Sciences. 1998. Vol. 362. № 7. P. 951-954.
Bogatikov O.A., Melekestsev I.V., Gurbanov A.G., Katov D.M., Puriga A.I. The Elbrus caldera in the northern Caucasus // Doklady Earth Sciences. 1998. Vol. 363 A. № 9. P. 1202-1204.
Bogatikov O.A., Melekestsev I.V., Gurbanov A.G., Sulerzhitskii L.D., Katov D.M., Puriga A.I. Radiocarbon dating of holocene eruptions of the Elbrus Volcano in the northern Caucasus, Russia // Doklady Earth Sciences. 1998. Vol. 363. № 8. P. 1093-1095.
Bogoyavlenskaya G.E., Braitseva O.A., Melekestsev I.V., Kirianov V.Yu., Dan Miller C. Catastrophic eruptions of the directed-blast type at Mount St. Helens, Bezymianny and Shiveluch volcanoes // Journal of Geodynamics. 1985. Vol. 3. № 3-4. P. 189-218. doi:10.1016/0264-3707(85)90035-3.    Аннотация
This paper describes catastrophic eruptions of Mount St. Helens (1980), Bezymianny (1955–1956), and Shiveluch (1964) volcanoes. A detailed description of eruption stages and their products, as well as the quantitative characteristics of the eruptive process are given. The eruptions under study belong to the directed-blast type. This type is characterized by the catastrophic character of the climatic stage during which a directed blast, accompanied by edifice destruction, the profound ejection of juvenile pyroclastics and the formation of pyroclastic flows, occur. The climatic stage of all three eruptions has similar characteristics, such as duration, kinetic energy of blast (10^17−10^18 J), the initial velocity of debris ejection, morphology and size of newly-formed craters. But there are also certain differences. At Mount St. Helens the directed blast was preceeded by failure of the edifice and these events produced separable deposits, namely debris avalanche and directed blast deposits which are composed of different materials and have different volumes, thickness and distribution. At Bezymianny, failure did not precede the blast and the whole mass of debris of the old edifice was outburst only by blast. The resulting deposits, represented by the directed blast agglomerate and sand facies, have characteristics of both the debris avalanche and the blast deposit at Mount St. Helens. At Shiveluch directed-blast deposits are represented only by the directed-blast agglomerate; the directed-blast sand facies, or blast proper, seen at Mount St. Helens is absent. During the period of Plinian activity, the total volumes of juvenile material erupted at Mount St. Helens and at Besymianny were roughly comparable and exceeded the volume of juvenile material erupted at Shiveluch, However, the volume of pyroclastic-flow deposits erupted at Mount St. Helens was much less.
The heat energy of all three eruptions is comparable: 1.3 × 10^18, 3.8−4.8 × 10^18 and 1 × 10^17 J for Shiveluch, Bezymianny, and Mount St. Helens, respectively.
Bogoyavlenskaya G.E., Girina O.A. Bezymianny volcano: 50 years of activity // Abstracts. 5rd Biennial Workshop on Subduction Processes emphasizing the Japan-Kurile-Kamchatka-Aleutian Arcs (JKASP-5). 2006. P. 129 doi: P 601.
Bogoyavlenskaya G.E., Girina O.A. Discriminations in Generation of pyroclastic deposit types from andesitic volcanoes of Kamchatka (in the Bezymianny volcano case) // IUGG. XXI General Assembly. Colorado. 1995. P. B 410
Bogoyavlenskaya G.E., Kirsanov I.T., Firstov P.P., Girina O.A. Bezymianny (Kamchatka). 1984-1985 eruptions and related pyroclastic deposits // SEAN Bulletin. 1986. № 4. P. 15-20.
Bogoyavlenskaya G.E., Naumov V.B., Tolstykh M.L., Ozerov A.Yu., Khubunaya S.A. Magma compositions of Bezymianny, Shiveluch and Karymsky volcanoes according to the data on study of glass inclusions (Kamchatka) // Abstracts of IAVCEI General Assembly, 18-22 July 2000. Bali, Indonesia. 2000. P. 87

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