Institute of Volcanology and Seismology
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К расчёту выноса тепла по данным тепловизионных исследований (на примере вулкана Мутновский, Камчатка)
No full textПрименение цифрового тепловизора при исследовании вулканов требует поиска соотношений параметров тепломассобмена с регистрируемой температурой поверхности. Естественным является расчёт радиационных теплопотерь. В статье предлагается и используется расчёт аномального (дополнительного) радиационного теплопотока от гидротермальных аномалий, показана возможность расчёта через радиационный поток теплопотерь на распределённых источниках типа «парящий грунт». Локализованы места изменения конфигурации термоаномалий в период между тепловизионным аэросъёмками 2009 и 2013 гг
Минералогия пород вулканов Острый и Плоский Толбачиков, исторических извержений и первого этапа формирования зоны шлаковых конусов
No full textPlagioclase lapilli and phenocrysts in the lavas of the 2012-2013 Tolbachik Fissure eruption
No full textThe 2012-2013 Tolbachik Fissure eruption started from lava gushing and effusion in the Menyailov vent on November 27 th , 2012; after three days the activity of this vent ceased and the eruption continued from the Naboko vent until its end in September 2013. The eruption produced about 0.7 km 3 of high-Al basaltic trachyandesites (Dvigalo et al., 2014). At Menyailov vent SiO2 concentrations were as high as 55.35 wt.% and K2O -2.67 wt.% -higher than in any previously erupted rocks in Tolbachik monogenetic area. From the beginning of December, SiO 2 concentration in lavas dropped by 2 wt.% and remained at this level until the end of eruption. MgO, TiO2, Mg# increased, K2O, Na2O decreased slightly. Most prominent change we observe in K2O/MgO ratio, which was about 0.7 in the Menyailov vent rocks and became 0.5 in the Naboko vent rocks. Details of the geochemical composition of the volcanic rocks produced by this eruption are reported elsewhere (Volynets et al., 2013, Volynets et al., 2014 a, b); here we present the results of the geochemical study of the main phenocrysts in the lavas – plagioclase. For the detailed geochemical study of the plagioclase we selected two samples from the Naboko vent (Pl-phyric lavas, erupted in February and August) and five crystal lapilli (two of them were erupted in December 2012, and three – during 2013, when the new cone has been already built). Plagioclases in these lavas are represented by two generations of labradorite and bytownite. Pl phenocrysts of the 1 st generation are large (up to 2 cm on the long axis) strongly resorbed at the edges and sometimes in the cores as well, containing lots of glass inclusions. Pl subphenocrysts of the 2 nd generation are smaller (less than 500 µm), usually nonresorbed and clean, having euhedral facets. Normal, reversed and patchy zoning are typical for all studied crystals (fig.1, I and II). Maximum concentrations of An (up to 83% at compositional variation between An50 and 74) has been measured in the patchy zones. Crystal lapilli are characterized by the oscillatory zoning with An fluctuations around An57-63 (fig. 1, III and IV). This kind of zoning is the result of the diffusion control of Pl growth at low growth rates (Sibley et al., 1976). The edges of lapilli are usually rich of glassy inclusions, tunnel-like dissolution structures, Ol, Px, Mt inclusions (fig. 1, III and IV). There are abundant resorption zones in lapilli, with plenty of glassy inclusions. These zones are characterized by the patchy zoning with An concentration jumps up to An74; usually these high-An areas are observed near the inclusions of glass. At the edges of lapilli there are zones with An gradual decrease towards the rim from An 74 to An61.
Plagioclase lapilli and phenocrysts in the lavas of the 2012-2013 Tolbachik Fissure eruption
Petrology and geochemistry of the Tolbachik stratovolcano
No full textThe numerous of national and international publications were dedicated to Plosky Tolbachik volcano eruptions and adjacent monogenetic cones, which were erupted repeatedly during Holocene, including historical time [i.e. Vlodavets, 1937; Popkov, 1946; Peep, 1946, 1954; Menyailov, 1953; Sirin and Farberov, 1963; Kirsanov et al., 1974; Ivanov and Khrenov, 1979; Fedotov, 1984; Krivenko, 1990; Kersting, 1995; Tatsumi et al., 1995; Hochstaedter et al., 1996; Kepezhinskas et al., 1997; Turner et al., 1998; Pineau et al., 1999; Volynets et al., 2000; Churikova et al., 2001; Münker et al., 2004; Portnyagin et al., 2007; Volynets et al., 2013]. However, all these data mainly relates to monogenetic cones, but the information on stratovolcanoes itself practically absent. There are only few papers on Ostry and Plosky Tolbachik stratovolcanoes focusing on geology [Ermakov and Vazheevskaya, 1973], petrography and some petrochemistry of the rocks [Ermakov, 1977; Flerov and Melekestsev, 2013]. The modern geochemical and isotope studies of the stratovolcanoes were never achieved. In this report we present geological, petrographical, petrochemical, geochemical and some K-Ar data on the rocks of Tolbachik massif. The present report based on representative collection of 154 samples from stratovolcanoes, dikes, monogenetic cones of different ages, including last 2012-2013 eruption. Additionally our study included samples separately standing edifice of Povorotnaya mount, which age according to K-Ar dating is 0.306±0.01 Ма
Coastal staircase sequences reflecting sea-level oscillations and tectonic uplift during the Quaternary and Neogene
No full textMany coasts feature sequences of Quaternary and Neogene shorelines that are shaped by a combination of sealevel oscillations and tectonics.We compiled a global synthesis of sea-level changes for the following highstands: MIS 1, MIS 3, MIS 5e and MIS 11. Also, we date the apparent onset of sequences of paleoshorelines either from published data or tentatively extrapolating an age for the uppermost, purported oldest shoreline in each sequence.
Including themost documentedMIS 5e benchmark, weidentify 926 sequences out ofwhich 185 also feature Holocene shorelines. Six areas are identified where elevations of the MIS 3 shorelines are known, and 31 feature elevation data for MIS 11 shorelines. Genetic relationships to regional geodynamics are further explored based on the elevations of the MIS 5e benchmark. Mean apparent uplift rates range from 0.01 ± 0.01 mm/yr (hotspots) to 1.47 ± 0.08 mm/yr (continental collision). Passive margins appear as ubiquitously uplifting, while tectonic segmentation is more important on active margins. From the literature and our extrapolations, we infer ages for the onset of formation for ~180 coastal sequences. Sea level fingerprinting on coastal sequences started at least during mid Miocene and locally as early as Eocene.Whether due to the changes in the bulk volume of seawater or to the temporal variations in the shape of ocean basins, estimates of eustasy fail to explain the magnitude of the apparent sea level drop. Thus, vertical ground motion is invoked, and we interpret the longlasting development of those paleoshore sequences as the imprint of glacial cycles on globally uplifted margins in response to continental compression. The geomorphological expression of the sequences matches the amplitude and frequency of glacial cyclicity. Frommiddle Pleistocene to present-day, moderately fast (100,000 yrs) oscillating sea levels favor the development of well identified strandlines that are distinct from one another.
Pliocene and Lower Pleistocene strandlines associated with faster cyclicity (40,000 yrs) are more compact and easily merge into rasas, whereas older Cenozoic low-frequency eustatic changes generally led to widespread flat-lying coastal plains
Известково-щелочные и субщелочные базальты и андезибазальты вулканов Ключевской, Харчинский и Плоский Толбачик (ТТИ-50) — вулканические продукты разноглубинной мантии
No full textОдной из проблем магматической петрологии и геохимии является выяснение причин поперечной геохимической зональности в островных дугах [11, 12]. Известно, что поперечная геохимическая зональность поперёк островной дуги выражается в смене толеитовых (низкокалиевых) базальтов на известково-щелочные (среднекалиевые) и субщелочные (высококалиевые), с востока на запад. В районе Ключевской группы вулканов эта закономерность нарушается, так как здесь на ограниченной площади встречены продукты известково-щелочных и субщелочных (трахибазальтовых) магм
Вулкан Эбеко в 2012–2013 гг.
No full textПриводятся данные о состоянии вулкана Эбеко в 2012–2013 гг.: фумарольная активность, состав газов, гидротермальные взрывы на Юго-Восточном фумарольном поле. Обсуждаются причины гидротермальных взрывов. Дается оценка активности вулкана