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Holocene eruptive history of Shiveluch volcano. Kamchatka Peninsula
Abstract
The Holocene eruptive history of Shiveluch volcano, Kamchatka Peninsula, has been reconstructed using geologic mapping, tephrochronology, radiocarbon dating, XRF and microprobe analyses. Eruptions of Shiveluch during the Holocene have occurred with irregular repose times alternating between periods of explosive activity and dome growth. The most intense volcanism, with frequent large and moderate eruptions occurred around 6500-6400 BC, 2250-2000 BC, and 50-650 AD, coincides with the all-Kamchatka peaks of volcanic activity. The current active period started around 900 BC; since then the large and moderate eruptions has been following each other in 50-400 yrs-long intervals. This persistent strong activity can be matched only by the early Holocene one. Most Shiveluch eruptions during the Holocene produced medium-K, hornblende-bearing andesitic material characterized by high MgO (2.3-6.8 wt %), Cr (47-520 ppm), Ni (18-106 ppm) and Sr (471-615 ppm), and low Y ( 2.5 km 3 of tephra. More than 10 debris avalanches took place only in the second half of the Holocene. Extent of Shiveluch tephra falls exceeded 350 km; travel distance of pyroclastic density currents was >22 km, and that of the debris avalanches ≤20 km.
... Holocene Shiveluch eruptions are dominated by andesites, and amphibole phenocrysts in the erupted andesites preserve a complex history of recharge by partially crystalline basaltic magmas in a shallow magma reservoir (e.g., Volynets et al. 1997;Dirksen et al. 2006;Humphreys et al. 2006Humphreys et al. , 2008Ponomareva et al. 2007b;Ferlito 2011;Gorbach and Portnyagin, 2011;Gorbach et al. 2013Gorbach et al. , 2016. Shiveluch is of particular interest because its magmas are thought to be extremely hydrous (e.g., Portnyagin et al. 2007), with some estimates of water content as high as 6 wt% H 2 O (Gavrilenko et al. 2016a), making it one of the most hydrous volcanoes in the world, comparable to Mt. Shasta in the Cascade Arc. ...
... Shiveluch is the northernmost active volcano in the CKD. It is composed of two overlapping eruptive centers: Old Shiveluch (3283 m a.s.l; Ponomareva et al. 2007b) and Young Shiveluch (2800 m a.s.l; Ponomareva et al. 2007b;Fig. ...
... It is composed of two overlapping eruptive centers: Old Shiveluch (3283 m a.s.l; Ponomareva et al. 2007b) and Young Shiveluch (2800 m a.s.l; Ponomareva et al. 2007b;Fig. 1). ...
Mafic enclaves preserve a record of deep differentiation of primitive magmas in arc settings. We analyze the petrology and geochemistry of mafic enclaves from Shiveluch volcano in the Kamchatka peninsula to determine the differentiation histories of primitive magmas and to estimate their pressures, temperatures, and water contents. Amphibole inclusions in high forsterite olivine suggest that the primitive melt was superhydrous (i.e., > 8 wt% H 2 O) and was fractionating amphibole and olivine early on its liquid line of descent. We find that the hydrous primitive melt had liquidus temperatures of 1062 ± 48 °C and crystallized high Mg# amphibole at depths of 23.6-28.8 km and water contents of 10-14 wt% H 2 O. The major and trace element whole-rock chemistry of enclaves and of published analyses of andesites suggest that they are related through fractionation of amphibole-bearing assemblages. Quantitative models fractionating olivine, clinopyroxene, and amphibole reproduce geochemical trends defined by enclaves and andesites in variation diagrams. These models estimate 0.2-12.2% amphibole fractionated from the melt to reproduce the full range of enclave compositions, which overlaps with estimates of the amount of amphibole fractionated from parental melts based on whole-rock dysprosium contents. This contribution extends the published model of shallow processes at Shiveluch to greater depths. It provides evidence that primitive magmas feeding arc volcanoes may be more hydrous than estimated from other methods, and that amphibole is an important early fractionating phase on the liquid line of descent of superhydrous, primitive mantle-derived melts.
... Shiveluch is the most productive and highly explosive volcano on the Kamchatka Peninsula and one of the most active dome-building volcanoes worldwide. The drastic predominance of amphibole-bearing andesites at all stages of volcanic evolution since the Late Pleistocene until present distinguishes Shiveluch among the other Kamchatka volcanoes (e.g., Melekestsev et al. 1991;Volynets et al. 1997;Ponomareva et al. 2007Ponomareva et al. , 2015Gorbach et al. 2013). Catastrophic plinian eruptions alternating with lava dome growth accompanied by voluminous pyroclastic flows, debris avalanches, lahars and ash falls are the typical features of Shiveluch eruptive style in the last 10 ka (Ponomareva et al. 2007). ...
... The drastic predominance of amphibole-bearing andesites at all stages of volcanic evolution since the Late Pleistocene until present distinguishes Shiveluch among the other Kamchatka volcanoes (e.g., Melekestsev et al. 1991;Volynets et al. 1997;Ponomareva et al. 2007Ponomareva et al. , 2015Gorbach et al. 2013). Catastrophic plinian eruptions alternating with lava dome growth accompanied by voluminous pyroclastic flows, debris avalanches, lahars and ash falls are the typical features of Shiveluch eruptive style in the last 10 ka (Ponomareva et al. 2007). The historic record includes two plinian eruptions (February 1854 andNovember 1964) alternated by lava dome growth (Melekestsev et al. 2004). ...
... Young Shiveluch had at least sixty large eruptions in the Holocene that were large enough to be preserved in the regional tephra records (Ponomareva et al., 2007). These eruptions generated thick pyroclastic flows, debris avalanches, ash falls, and lahars distributed mostly to the south of the eruptive center, and have formed a pyroclastic sloping field with an area of nearly 400 km 2 . ...
Shiveluch is one of the most active explosive volcanoes worldwide. During the last рlinian eruption in 1964 and the following (1980-current time) dome-forming eruptions Shiveluch has produced andesites and dacites (SiO2 ~ 60–64 wt%) containing variably zoned, compositionally and texturally diverse amphibole phenocrysts. In this work, we attempt to decode the complex zoning of the amphibole crystals in the 55-year series of pumice, dome rocks and mafic enclaves in order to reconstruct the most recent evolution of the volcano plumbing system.
The amphibole zoning in Shiveluch andesites reveals correlation with the style and date of eruption. High-Al cores mantled by low-Al rims in amphiboles from the 1964 plinian eruption record a drastic decrease of pressure and rapid magma ascent from the lower crust to the shallow magma chamber. Typically unzoned and often opacitized low-Al crystals from the early dome-building episodes in 1980–1981 and 1993–1995 reflect magma crystallization in the shallow magma chamber. Complexly zoned amphiboles from andesites erupted in 2000s indicate replenishment of the shallow magma chamber with mafic magma and syn-eruptive mixing processes. Amphibole-based barometric calculations obtained by different approaches indicate that the Shiveluch plumbing system is complex and comprises two, mafic and silicic magma storage zones at ~15–20 km and ~ 5–6 km depths. We suggest that both episodes of the plinian eruption in 1964 and the extensive dome growth in 2001–2016 were driven by influx of mafic magma in the shallow storage zone beneath Shiveluch. The mafic replenishment likely preceded the 1964 plinian eruption and repeatedly occurred during the period of extensive dome growth in 2001–2016. The variable styles of the recent Shiveluch eruptions may be controlled by the relative volume of the mafic recharges and their thermal and viscosity effects on the efficiency of magma mixing.
... The Kamchatka Peninsula is one of the most active volcanic regions in the world. The volcanoes of Kamchatka are assigned to three main volcanic belts (Fig. 21.1b): Sredinny Range, Eastern volcanic front (EVF) and Central Kamchatka depression (CKD) (Portnyagin et al. 2005;Ponomareva et al. 2007;Bindeman et al. 2010). ...
... Historically active volcanoes are located only at the Eastern volcanic front and in the CKD. Up to 37 large volcanic centers have been active during the Holocene (Ponomareva et al. 2007). Periods of strong Holocene volcanic activity occurred within the time intervals of 7500-7800 and 1300-1800 14 C years BP (Braitseva et al. 1995). ...
... Periods of strong Holocene volcanic activity occurred within the time intervals of 7500-7800 and 1300-1800 14 C years BP (Braitseva et al. 1995). Most Late Pleistocene calderas were formed 30,000-40,000 years ago (Braitseva et al. 1995;Ponomareva et al. 2007;Bazanova et al. 2016). The explosive eruptions have resulted in widespread dispersal of tephra-fall deposits. ...
An effect of a single-phase oxidation process on the hysteresis charac�teristics and blocking temperature of magnetite has been carried out within the
framework of the model of core-shell nanoparticle. It has been shown that an
increase of the degree of oxidation of magnetite grains results in a decrease of the
spontaneous magnetization and slight change of coercive field and remanent sat�uration magnetization to spontaneous magnetization ratio. Increase of the portion of
maghemite lead to decrease of the blocking temperature. All results are in agree�ment with an experimental data.
... тонической позиции район кгВ активно изучался с 1930 г. В настоящее время о кгВ опубликовано более тысячи работ, включая исследования в области петрологии [Флеров и др., 1984;Флеров и овсянников, 1991;Хренов и др., 1991;Хубуная и др., 1993;Volynets, 1994;Kersting, Arculus, 1995;Волынец и др., 1997а, 2000озеров и др., 1997;Хубуная, соболев, 1998;Turner et al., 1998Turner et al., , 2007Pineau et al., 1999;Dorendorf et al., 2000;Ozerov, 2000;миронов и др., 2001;чурикова и др., 2001;Churikova et al., 2001Churikova et al., , 2007Churikova et al., , 2013Ishikawa et al., 2001;Yogodzinski et al., 2001;Dosseto et al., 2003;Bindeman et al., 2004;Münker et al., 2004;Portnyagin et al., 2007а, 2007б;Auer et al., 2009;горбач, Портнягин, 2011;миронов, Портнягин, 2011;Almeev et al., 2013а, b;Gorbach et al., 2013;Dosseto, Turner, 2014], геофизики [токарев, зобин, 1970;балеста, 1991;Gorelchik et al., 1997;Levin et al., 2002;Park et al., 2002;горельчик и др., 2004;Davaille, Lees, 2004;Хубуная и др., 2007;сенюков и др., 2009;Федотов и др., 2010Thelen et al., 2010;Koulakov et al., 2011;кугаенко и др., 2013;Grapenthin et al., 2013;Iwasaki et al., 2013;West, 2013], геохронологии [брайцева и др., 1990;Calkins, 2004;Ponomareva et al., 2006Ponomareva et al., , 2007Пономарева и др., 2008;Певзнер и др., 2014] и другим смежным дисциплинам [овсянников и др., 1985;гирина, 1986;белоусов, белоусова, 1995муравьев и др., 2002;мелекесцев, 2005;гришин, Шляхов, 2009;Gilichinsky et al., 2010;гордеев, гирина, 2014]. основная часть всех этих исследований сконцентрирована на изучении ныне действующих вулканов и продуктов их извержений. ...
... зона моногенных конусов в массиве Плоские сопки, судя по всему, прекратила свою деятельность 10.2 тыс. лет назад [Ponomareva et al., 2007], и примерно в это же время [брайцева и др., 1984а] начала работать вторая трещинная зона, формирующая обширные лавовые поля и шлаковые конусы в толбачинском массиве, которая активна до сих пор (см. рис. ...
... FeO * представляет общее содержание окислов железа в образце, представленное как FeO. данные были взяты из [Эрлих, 1966;ермаков, Важеевская, 1973;ермаков, 1977;чурикова, 1993;Portnyagin et al., 2007а;иванов, 2008;Auer et al., 2009;горбач, Портнягин, 2011;Bryant et al., 2011;Флеров, мелекесцев, 2013;Almeev et al., 2013b;Churikova et al., 2013;Gorbach et al., 2013;Ponomareva et al., 2007;Turner et al., 2013;Kayzar et al., 2014] рис. 2.6. ...
Ключевская группа вулканов (КГВ) располагается в северной части Центральной Камчатской депрессии (ЦКД) и является одной из самых крупных и наиболее активных вулканических структур на Камчатке и в мире. В южной части КГВ находится позднеплейстоцен-голоценовый Толбачинский массив, который извергался неоднократно в течение голоцена и исторического времени.
Первые исторические описания активности Толбачинского массива были выполнены русским исследователем Степаном Крашенинниковым, сделавшим записи об извержении Толбачика 1739 года. Позднее, в течение 20-го столетия, исследователи изучали и публиковали данные о многочисленных доисторических и исторических извержениях как на вершине вулкана Плоский Толбачик, так и в зоне моногенных конусов на юго-юго-западном фланге массива. В основном эти работы были посвящены динамике извержений и постэруптивным изменениям, морфологии вершинной части вулкана.
Всемирную известность вулкан Толбачик приобрел только после Большого трещинного Толбачинского извержения 1975–1976 гг. (БТТИ), когда в течение полутора лет на южном склоне вулкана сформировались четыре новых моногенных конуса и связанные с ними лавовые поля. Это извержение излило на поверхность высоко-Mg и высоко-Al базальты с общим объемом продуктов извержения (лава и тефра) 2,2 км3, что сделало его одним из крупнейших извержений XX века. В период между БТТИ и извержением 2012–2013 гг. множество публикаций в российских и международных журналах представляли данные об извержении Толбачика 1975–1976 гг. Благодаря этому к настоящему времени большинство существующей информации по Толбачинскому вулканическому массиву относится к извержению 1975–1976 гг. В то же время другие части этого грандиозного массива и прилегающие к нему моногенные конусы и лавовые поля изучались в гораздо меньшей степени.
В той же зоне моногенных конусов, что и извержение 1975–1976 гг., в 2012 г. началось новое крупное извержение – Трещинное Толбачинское извержение имени 50-летия ИВиС (ТТИ-50). Задача настоящего раздела – дать обзор накопленных знаний и существующих гипотез по геологии, тектонике, петрологии, геохимии, геофизике и истории развития Толбачинского вулканического массива к началу ТТИ-50.
... Породы имеют высокую магнезиальность (Mg/Mg + Fe 2+ = = 0.56-0.59), что типично для пород Молодого Шивелуча [Волынец и др., 1997;Горбач, Портнягин, 2011;Ponomareva et al., 2007]. ...
... На рис. 9 показаны вариации главных элементов и выбранных редких элементов в изверженных продуктах 2001-2013 гг. и их сравнение с составами лав и пирокластики, которые характеризуют период деятельности Молодого Шивелуча по данным [Горбач, Портнягин, 2011;Ponomareva et al., 2007]. Точки составов продуктов современных извержений расположены в наиболее кислой части всего спектра пород, изверженных в голоцене. ...
... %, редких элементов -в г/т. Cоставы лав и пирокластики Молодого Шивелуча приведены по данным [Горбач, Портнягин, 2011;Ponomareva et al, 2007]. [ Dirksen et al., 2006;Humhpreys et al., 2006]. ...
... The Shiveluch andesitic volcano is located close to the junction of the Kamchatka and Aleutian arcs. It is active and large ($1000 km 3 ) and began erupting in the late Pleistocene (Ponomareva et al., 2007;Gorbach et al., 2013). Shiveluch erupts predominantly silicic magmas (andesites and dacites) with adakitic characteristics (e.g. ...
... Gorbach & Portnyagin, 2011); however, Shiveluch has had two episodes of mafic eruptions (3600 bp and 7600 bp), and resulting basalts are phlogopite-and amphibole-bearing (Volynets et al., 1997). We analyzed olivine grains from Shiveluch basaltic tephra sample 00K15 (3600 BP mafic eruption); the complete description and whole-rock chemistry have been provided by Ponomareva et al. (2007). ...
... For the Shiveluch volcano located north of Klyuchevskoy, we calculate 6Á4% H 2 O contents for parental melts in equilibrium with olivine having an Mgnumber of 92Á5. This high value of H 2 O content for the Shiveluch parental magma may help to explain the existence of high-magnesium (MgO is $11 wt %) basaltic rocks bearing phlogopite and amphibole (Volynets et al., 1997;Ponomareva et al., 2007;Gorbach & Portnyagin, 2011). Possible contributions to the high water content in Shiveluch parental magmas are lower mantle wedge temperatures, less peridotite material assimilated by hydrous eclogite melts, and a higher relative contribution of water from the slab (Portnyagin et al., 2007a). ...
High precision electron microprobe analyses were obtained on olivine grains from Klyuchevskoy, Shiveluch and Gorely volcanoes in the Kamchatka Arc; Irazú, Platanar, 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 D(CaO)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 μm 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.
... The southern sector of the volca nic massif was destroyed by a large-scale collapse before the onset of the second stage of the Late Pleis tocene glaciation (Melekestsev et al., 1991). The erup tion center of Young Shiveluch in the northwestern part of the collapse crater significantly erupted no less than 60 times in the Holocene, and these eruptions gave rise to thick pyroclastic flows, debris avalanches, ash falls, and lahars (Ponomareva et al., 2007). A series of satellite extrusion domes of the Karan group (Figs. 2, 3b), which were produced roughly simultaneously with Young Shiveluch, sit on the western slope of Old Shiveluch. ...
... Conceivably, the age of these compositionally heterogeneous flows can be corre lated with the eruption at 3700 14 C years, which pre dated the eruption of Ol-Cpx-Hbl ± Pl basalt at 3600 14 C years. Judging by the database in (Ponomareva et al., 2007), only the tephra of this eruption has frag ments of heterogeneous composition (samples 00K20A1, 00K20A2, 00K20B, 00K22, and 00K23) identical to the contrasting composition of lavas in the southeastern sector. ...
... As can be seen in Fig. 11, the fractional crystallization of olivine in a basaltic melt should have rapidly depleted Ni in the melt The composition of basalts of the eruption at 7600 14 C years is according to (Volynets et al., 1997). The gray field shows the com position of proximal pyroclastic deposits of Young Shiveluch volcano (Ponomareva et al., 2007). ...
... Presently, high-K rocks are restricted to the southern and western part of the Klyuchevskoy Group (Tolbachik, ushkovsky), occur in the Shiveluch Volcanic Group and compose the Late Pleistocene cinder cones and lava flows near Nachikinsky volcano. In contrast to southern Kamchatka, low-K rocks and highly evolved rocks (dacites and rhyolites) are extremely rare in the CKD and have not been documented among Holocene eruptions [e.g., Fedotov and Masurenkov, 99;Krivenko, 99;Volynets, 994;Ponomareva et al. 2007b]. Modal and chemical compositions of CKD rocks exhibit systematic variations along the strike of the volcanic arc [e.g., Fedotov and Masurenkov, 99;Yogodzinski et al. 200;Volynets, 994;Volynets et al. 1997;999;2000;Churikova et al. 200], but these variations have not been evaluated in detail thus far. ...
... rocks from Zarechny volcano and many rocks from Shiveluch volcano are high Mg# calc-alkaline basaltic andesites and andesites [e.g. Volynets et al. 997;999, 2000;Churikova et al. 200;Ponomareva et al. 2007b] and have lower FeO, CaO, TiO 2 and higher SiO 2 and Na 2 O at similar MgO compared to Klyuchevskoy volcano ( Figure 4). A distinctive feature of these rocks is the wide occurrence of amphibole, which is common not only in andesites but is also present in more basic rock types together with Ca-pyroxene and olivine. ...
... A distinctive feature of these rocks is the wide occurrence of amphibole, which is common not only in andesites but is also present in more basic rock types together with Ca-pyroxene and olivine. rare rocks with Mg-rich phlogopite phenocrysts, which are unique in the CKD, were described on Kharchinsky volcano (crater extrusion) and among the Holocene pyroclastic deposits of Shiveluch volcano (basaltic tephra, 3600 BP) [Volynets et al. 999;2000;Ponomareva et al. 2007b]. Petrologic information about the northern CKD volcanoes is relatively abundant [Fedotov and Masurenkov, 99;Volynets et al. 997;998;999;2000;, although the amount of high quality geochemical data is still relatively small compared to the great emphasis to these volcanoes in the literature. ...
... Characteristics of glass from dated proximal pyroclastic units allow us to provide a set of analyses that can be used as a reference for distal correlations of Shiveluch tephras. This paper extends and refines the earlier published Shiveluch eruptive history (Ponomareva et al. 2007) and provides new insights into temporal variability of its magma compositions. ...
... The older pyroclastic sequence was probably removed from the volcano's slopes by glacial erosion. Sixty prominent pyroclastic units erupted since ~11 ka have been recognized and dated (Ponomareva et al. 2007). Preserved Holocene lava flows are rare (Gorbach and Portnyagin 2011) and extend ≤4 km from vent. ...
... YSH eruptions are dominated by medium-K amphibolebearing andesites which were fairly uniform throughout the Holocene, with the exception of two large basalt-basaltic andesite eruptions (Volynets et al. 1997;Ponomareva et al. 2007). Electron microprobe analyses of rhyolitic glass from thirteen Shiveluch tephras yielded similar compositions, so these tephras could not be geochemically distinguished (Kyle et al. 2011). ...
The ~16-ka-long record of explosive eruptions from Shiveluch volcano (Kamchatka, NW Pacific) is refined using geochemical fingerprinting of tephra and radiocarbon ages. Volcanic glass from 77 prominent Holocene tephras and four Late Glacial tephra packages was analyzed by electron microprobe. Eruption ages were estimated using 113 radiocarbon dates for proximal tephra sequence. These radiocarbon dates were combined with 76 dates for regional Kamchatka marker tephra layers into a single Bayesian framework taking into account the stratigraphic ordering within and between the sites. As a result, we report ~1,700 high-quality glass analyses from Late Glacial–Holocene Shiveluch eruptions of known ages. These define the magmatic evolution of the volcano and provide a reference for correlations with distal fall deposits. Shiveluch tephras represent two major types of magmas, which have been feeding the volcano during the Late Glacial–Holocene time: Baidarny basaltic andesites and Young Shiveluch andesites. Baidarny tephras erupted mostly during the Late Glacial time (~16–12.8 ka BP) but persisted into the Holocene as subordinate admixture to the prevailing Young Shiveluch andesitic tephras (~12.7 ka BP–present). Baidarny basaltic andesite tephras have trachyandesite and trachydacite (SiO2 < 71.5 wt%) glasses. The Young Shiveluch andesite tephras have rhyolitic glasses (SiO2 > 71.5 wt%). Strongly calc-alkaline medium-K characteristics of Shiveluch volcanic glasses along with moderate Cl, CaO and low P2O5 contents permit reliable discrimination of Shiveluch tephras from the majority of other large Holocene tephras of Kamchatka. The Young Shiveluch glasses exhibit wave-like variations in SiO2 contents through time that may reflect alternating periods of high and low frequency/volume of magma supply to deep magma reservoirs beneath the volcano. The compositional variability of Shiveluch glass allows geochemical fingerprinting of individual Shiveluch tephra layers which along with age estimates facilitates their use as a dating tool in paleovolcanological, paleoseismological, paleoenvironmental and archeological studies. Electronic tables accompanying this work offer a tool for statistical correlation of unknown tephras with proximal Shiveluch units taking into account sectors of actual tephra dispersal, eruption size and expected age. Several examples illustrate the effectiveness of the new database. The data are used to assign a few previously enigmatic wide-spread tephras to particular Shiveluch eruptions. Our finding of Shiveluch tephras in sediment cores in the Bering Sea at a distance of ~600 km from the source permits re-assessment of the maximum dispersal distances for Shiveluch tephras and provides links between terrestrial and marine paleoenvironmental records.
... The Kamchatka peninsula is situated at the junction of the Kuril-Kamchatka and Aleutian subduction zones, where the Pacific plate is subducting to the west beneath the Okhotsk plate (Seno et al. 1996;Krippner et al. 2018). Shiveluch is the northernmost active volcano on the Kamchatka peninsula and is one of the most active volcanoes in the region with an average magma discharge of ~ 0.015 km 3 /year (Ponomareva et al. 2007). The Holocene eruptive history of Shiveluch is characterized by alternating periods of explosive activity and dome growth, separated by periods of quiescence, with the most recent voluminous eruptive period beginning around 900 BCE (Ponomareva et al. 2007). ...
... Shiveluch is the northernmost active volcano on the Kamchatka peninsula and is one of the most active volcanoes in the region with an average magma discharge of ~ 0.015 km 3 /year (Ponomareva et al. 2007). The Holocene eruptive history of Shiveluch is characterized by alternating periods of explosive activity and dome growth, separated by periods of quiescence, with the most recent voluminous eruptive period beginning around 900 BCE (Ponomareva et al. 2007). ...
Shiveluch volcano (Kamchatka, Russia) is an active andesitic volcano with a history of explosive activity, dome extrusion, and structural collapse during the Holocene. The most recent major (> 1 km3) dome collapse occurred in November 1964, producing a ~ 1.5 km3 debris avalanche that traveled over 15 km from the vent and triggered a phreatic explosion followed by a voluminous (~ 0.8 km3) eruption of juvenile pyroclastic material. Seismic records suggest that the collapse was likely triggered by a magnitude 5.1 earthquake associated with the ascent of magma into the edifice. The geomechanical properties of the pre-1964 dome are unknown; accordingly, the mechanics of the collapse are poorly understood. This project employs numerical slope stability modeling using the finite element method to constrain probable ranges of geomechanical properties for the materials involved in the collapse, considering earthquake loading as the most likely triggering mechanism. Model results show good agreement with the 1964 collapse geometry considering Geological Strength Index and horizontal pseudo-static seismic coefficient ranges of 30–60 and 0.05–0.15 g, respectively, representing variably fractured and altered dome rocks under moderate earthquake loading, confirming that ground acceleration alone could have triggered the dome collapse. Deep-seated rotational sliding is the dominant failure mode, but local extension within the dome during failure appears to play an important role in the development of the collapse. The findings of this work allow for better forward modeling of potential future collapses, the results of which can be incorporated into regional hazard and risk assessments.
... The 2760 m-high Young Shiveluch is nested in the old collapse scar (Fig. 2g-h) and consists of overlapping domes and short andesite lava flows. It has produced at least 60 large eruptions >0.5 km 3 during the Holocene, emplacing pyroclastic density current, block-and ash-flow and minor to moderate ash fall deposits as well as a thick volcaniclastic apron made of debris avalanche and lahar units (Ponomareva et al. 1998(Ponomareva et al. , 2007Belousov et al. 1999;Pevzner et al. 2013). Young Shiveluch andesites are compositionally distinct from Old Shiveluch eruptives with lavas displaying much higher SiO 2 concentrations, i.e. 59.5-62.5% compared to 54.5-56.5% for pre-Holocene (Belousov et al. 1999). ...
... Likewise, Shiveluch volcano became unstable in the Holocene due to an abrupt shift to more viscous, high-silica magma compositions that changed the eruptive style to dominantly lava dome extrusion (Belousov et al. 1999). Repeated failure of Young Shiveluch produced at least 8 debris avalanches since 5.7 ka with volumes of 1-2.5 km 3 and recurrence intervals of 600-2000 yrs (Table 4) due to a high magma supply rate (36 * 10 6 tons/yr or *15 km 3 /kyr; Melekestsev et al. 1991;Ponomareva et al. 2007), an order of magnitude higher than typical of island arc volcanoes (Davidson and DeSilva 2000). At Volcán de Colima/Paleofuego at least 8 debris-avalanche units have been identified since 28 ka with volumes of 1-1.7 km 3 and 8.9 km 3 for the largest deposit (Cortes et al. 2010a;Roverato et al. 2011). ...
Large-scale edifice failure is a common process during the long lifespans of volcanoes worldwide with many experiencing repeated collapse. Here we use six well-studied stratovolcanoes and dome-complexes with evidence of multiple edifice failures to discuss the driving forces behind their cyclic growth and destruction as well as the frequency and nature of these processes. We evaluate the influence of magmatic, climatic and tectonic factors on the unstable nature of frequently collapsing volcanoes to highlight our current understanding of the relationship between long-term volcanic behaviour, sedimentation and magmatic evolution.
While a range of interactions between magmatic processes and edifice failures have been recognised, climate conditions only show overprinting effects on deposit characteristics and type of sedimentation. Variation in failure frequencies at the investigated volcanoes reflect differences in collapse volume and long-term edifice growth rates. Persistently active lava-dome complexes often experience small failures with high return intervals, while episodic activity and larger edifice dimensions of stratovolcanoes typically lead to lower-frequency, larger-scale collapse cycles. Ultimately, the potential for failure to occur and its maximum possible size depend on the physical properties of the edifice while the nature and timing of trigger events in relation to edifice preconditioning determine the eventual size of collapse.
... which is typical of the Young Shiveluch rocks (Volynets et al., 1997;Gorbach and Portnyagin, 2011;Pono-mareva et al., 2007). Figure 9 shows variations of the major elements and selected trace elements in the 2001-2013 ejecta, comparing these with the compositions of the lavas and pyroclastic material that are usually erupted by Young Shiveluch during its periods of activity according to (Gorbach and Portnyagin, 2011;Ponomareva et al., 2007). The data points for the ejecta of recent eruptions are in the most silicic part of the entire range of the Holocene ejecta. ...
... The major element concentrations are in wt %, those of trace elements are in g/t. The compositions of lavas and pyroclastics on Young Shiveluch are after(Gorbach and Portnyagin, 2011;Ponomareva et al., 2007). ...
This paper discribes characteristic features of the extrusive dome growth of the Young Shiveluch Volcano in 2001–2013 and analyzes variations in the chemical and mineralogic composition of magmas erupted during this period. It is shown that, compared with the earlier phases in the dome growth during 1980–1981 and 1993–1995, the andesites that were erupted in the 2000s are less homogeneous in bulk composition, crystal contents and contain phenocrysts, which differ in composition and the conditions of crystallization. These compositional feature of rocks are interpreted as resulting from convection in a shallow magma chamber, with the convection being caused by the arrival of a fresh portion of deep magma.
... Современная активность вулкана эруптивного центра Молодой Шивелуч -чередование масштабных плинианских извержений, слабых выбросов пеплово-газовых облаков и эпизодов активного роста экструзивного купола (Гиринa, 2006;Shevchenko, 2015). В голоцене зафиксировано 60 крупных извержений с объемом вулканитов более 1 км 3 (Ponomareva, 2007). Столь высокая продуктивность вулкана, вероятно, отражает специфику геодинамических процессов в этом районе. ...
... The Klyuchevskaya volcano group is located in the Central Kamchatka Depression ( Fig. 2A, B) and formed during the late Pleistocene period *40-50 K years ago (Braitseva et al., 1995) The Klyuchevskaya volcano group contains active volcanoes, for example, Plosky Tolbachik and Shiveluch. Thus, Shiveluch is considered to be one of the peninsula's largest and most active volcanoes with an estimated 60 substantial eruptions in the past 10 K years (Ponomareva et al., 2007). Regardless of active volcanism, the mountainous permafrost occurs at elevations higher than 1000 m asl with an average annual ground temperature between -4°C and -7°C (Abramov et al., 2008). ...
This article describes a study of frozen volcanic deposits collected from volcanoes Tolbachik and Bezymianny on the Kamchatka Peninsula, Russia, and Deception Island volcano, Antarctica. In addition, we studied suprasnow ash layers deposited after the 2007 eruptions of volcanoes Shiveluch and Bezymianny on Kamchatka. The main objectives were to characterize the presence and survivability of thermophilic microorganisms in perennially frozen volcanic deposits. As opposed to permafrost from the polar regions, viable thermophiles were detected in volcanic permafrost by cultivation, microscopy, and sequencing. In the permafrost of Tolbachik volcano, we observed methane formation by both psychrophilic and thermophilic methanogenic archaea, while at 37°C, methane production was noticeably lower. Thermophilic bacteria isolated from volcanic permafrost from the Deception Island were 99.93% related to Geobacillus stearothermophilus. Our data showed biological sulfur reduction to sulfide at 85°C and even at 130°C, where hyperthermophilic archaea of the genus Thermoproteus were registered. Sequences of hyperthermophilic bacteria of the genus Caldicellulosiruptor were discovered in clone libraries from fresh volcanic ash deposited on snow. Microorganisms found in volcanic terrestrial permafrost may serve as a model for the alien inhabitants of Mars, a cryogenic planet with numerous volcanoes. Thermophiles and hyperthermophiles and their metabolic processes represent a guideline for the future exploration missions on Mars.
... Shiveluch volcano is one of the most active, studied and geochemically characterized volcanoes in Kamchatka (e.g., Ponomareva et al., 2007Ponomareva et al., , 2015Ponomareva et al., , 2017. Rhyolitic glass compositions from Shiveluch tephra tend to be very similar to one another, consistently medium K 2 O between~2.5 and 3 wt%, with SiO 2 ranging between~73 and 77 wt% (Fig. 11, Table 5; e.g., Ponomareva et al., 2017;Portnyagin et al., 2020). ...
Lakes and bogs in northeastern North America preserve tephra deposits sourced from multiple volcanic systems in the Northern Hemisphere. However, most studies of these deposits focus on specific Holocene intervals and the latest Pleistocene, providing snapshots rather than a full picture. We combine new data with previous work, supplemented by a broad review of the characteristics and ages of potential source regions and volcanoes, to develop the first composite tephrostratigraphic framework covering the last ∼14,000 years for this region. We report new cryptotephra records from three ombrotrophic peat bogs—Irwin Smith (Michigan), Bloomingdale (New York), and Sidney Bog (Maine)—as well as new analyses and age models from previously reported sites, Nordan's Pond Bog (Newfoundland) and Thin-Ice Pond (Nova Scotia). A new tephra (Iliinsky) from the NGRIP and GRIP ice cores is also presented as it can be correlated to new data from these terrestrial records and helps validate radiocarbon age models. We identify 21 new tephra in addition to the 15 already known, several of which cover the entire region – the White River Ash east, Newberry Pumice, Ruppert (NDN-230), and Mazama. For the first time we find Mount St. Helens Yn (ca. 3660 cal yr BP) and a set P tephra (∼3000–2550 cal yr BP), and confirm the presence of Jala Pumice from Volcan Ceboruco, Mexico, and KS1 from Ksudach volcano, Kamchatka. We describe new “ultra-distal” tephra, including the early Holocene KS2 eruption, and propose correlations to volcanoes Iliinsky and Shiveluch of Kamchatka, and Ushishir of the Kurile Islands. Not all of these tephra represent large eruptions, with several plausible correlations to sub-Plinian events. Using Bayesian age-modeling, we present new age estimates for the newly described tephra, for tephra with previously poor age control, and for several proximal correlatives. Overall, we demonstrate northeastern North America's importance for providing transcontinental linkages between paleoenvironmental records and providing insights into ash distribution from different styles and sizes of eruptions.
... The area experiences frequent tectonic, volcanic and cyclonic activities (Jones & Solomina 2015). This is one of the world's most volcanically and tectonically active regions, with active eruptions occurring in the Late Pleistocene between 45 and 39 ka ago and 30 and 25 ka ago and enhanced volcanic activity occurring in the Early to Middle Holocene between 9.5 and 7.0 ka BP (Ponomareva et al. 2007). The Pacific Plate is actively subducting beneath the Kamchatka Peninsula at about 80-100 mm a À1 resulting in three distinct volcanic arcs. ...
The Kamchatka Peninsula (Russian Far East) remains among the least studied regions of eastern Asia. Recent studies revealed a high degree of palaeoenvironmental variability between different parts of the peninsula. We investigated semi‐aquatic (chironomids) and terrestrial (leaf wax biomarkers) proxies from a sediment core collected from Lake Sokoch (southern Kamchatka) to provide reconstruction of the mean July air temperature and variations in limnic conditions. The lake formed after 10.0 cal. ka BP as a result of postglacial warming and was fed by glacial meltwaters from neighbouring glaciers. Our data show a later beginning of the Holocene thermal maximum (HTM) relative to more northern sites in Kamchatka, Siberia and Chukotka and support climate model experiments that suggest that the HTM was delayed in southern and central Kamchatka by about 2000 years compared with Alaska and NE Siberia. Warm conditions prevailed between 10.0 and 6.4 cal. ka BP with a short spell of cool and dry climate around 8.2 cal. ka BP that might be related to the 8.2 ka cooling event. The HTM took place between 6.5 and 3.4 cal. ka BP with the warmest phase from 6.0 to 5.0 cal. ka BP. An onset of Neoglacial cooling at 3.4 cal. ka BP is consistent with the strengthening of both the Siberian High and the Aleutian Low. Warming between 1.2 and 0.9 cal. ka BP can be attributed to the Mediaeval Climate Anomaly. The LIA cooling is related to another strengthening of the Siberian High and the Aleutian Low. The modern warming, though weakly traced in our record, is consistent with the recent meteorological observations. The presented palaeoenvironment record confirms the earlier findings of spatial differences within Kamchatka in timing and magnitude of the major Holocene climate fluctuations and contributes towards understanding the expression of Holocene climate change in Kamchatka.
... The Kamchatka peninsula is situated at the junction of the Kuril-Kamchatka and Aleutian subduction zones where the Pacific plate is subducting to the west beneath the Okhotsk plate (Seno et al., 1996;Krippner et al., 2018). Shiveluch is the northernmost active volcano on the Kamchatka peninsula and is one of the most active volcanoes in the region with an average magma discharge of ~0.015 km 3 /year (Ponomareva et al., 2007). ...
Shiveluch volcano (Kamchatka, Russia) is an active andesitic volcano with a history of explosive activity, dome extrusion, and structural collapse during the Holocene. The most recent major (>1 km3) dome collapse occurred in November 1964, producing a ∽1.5 km3 debris avalanche that traveled over 15 km from the vent and triggered a phreatic explosion followed by a voluminous (∽0.8 km3) eruption of juvenile pyroclastic material. Seismic records suggest that the collapse was likely triggered by a magnitude 5.1 earthquake. The geomechanical properties of the pre-1964 dome are unknown; accordingly, the mechanics of the collapse are poorly understood. Here, we employ slope stability modeling using the finite element method to constrain probable ranges of geomechanical properties for the materials involved in the collapse, considering earthquake loading as the most likely triggering mechanism. Model results show good agreement with the 1964 collapse geometry considering Geological Strength Index and seismic coefficient ranges of 30 to 60 and 0.05 to 0.15 g, respectively, representing variably fractured and altered dome material under moderate earthquake loading. Deep-seated rotation is the dominant failure mode, but local extension within the dome appears to play an important role in the development of the collapse.
... In this work, we calculated new and more accurate ages for most of Holocene eruptions, which formed tephra layers in the proximal Avachinsky and Koryaksky tephra sequences. The age calibration model was based on 110 previously published and 67 new 14 C dates as well as 30 14 C dates and 2 calendar dates for six regional marker layers from other volcanoes reported elsewhere (Braitseva et al., 1995;Bazanova and Pevzner, 2001;Ponomareva et al., 2007bPonomareva et al., , 2017Zaretskaia et al., 2001;Zaretskaya et al., 2007;Pinegina et al., 2013;Pendea et al., 2017). Radiocarbon dating was performed at the Geological Institute of the Russian Academy of Sciences (Moscow) and Institute of Volcanology and Seismology (Petropavlovsk-Kamchatsky). ...
Avachinsky, Kozelsky, and Koryaksky volcanoes form one of the most volcanically active clusters in the Kamchatka volcanic arc and are located in close proximity of the cities of Petropavlovsk-Kamchatsky and Elizovo – the most populated area in Kamchatka. In this paper we report a compilation of new and revised previously published data on the eruptive history of these volcanoes during the past 13.5 ka. We identify 217 major explosive eruptions of these volcanoes, determine their ages using 207 radiocarbon dates and Bayesian statistical modeling, and characterize their tephra geochemically using major and trace element compositions of bulk samples (40 samples) and volcanic glass (75 samples).
Avachinsky volcano has been the most active during the Holocene time and had >150 explosive eruptions; Kozelsky volcano had only two eruptions in the early Holocene; and Koryaksky volcano produced 61 eruptions. Our new data confirm the onset of the Avachinsky Holocene activity at 11.3 cal ka and previously distinguished two major stages of Avachinsky eruptive history: stage I (8 – 3.8 ka) and stage II (3.8 ka – present). During stage I, eruptions were relatively rare, but they included six large pumice eruptions with tephra volumes exceeding 0.5 km3. Stage I tephras had low-K andesitic bulk compositions and low-K rhyolitic matrix glasses. The andesites likely sampled volatile-rich crystal mush from a long-lived magma chamber under Avachinsky volcano. The stage II started at ~3.8 ka with a powerful eruption and was related to the construction of the Young Cone inside the Avachinsky somma. The subsequent late Holocene eruptions were frequent, but only two of them reached the volume of ~0.2 km3. The stage II tephras are mostly cindery basaltic andesites containing well-crystallized glasses of andesitic composition. These tephras originate from smaller, perhaps more shallow magmatic reservoirs, and their matrix glasses are likely products of in-situ crystallization of relatively mafic magmas on their ascent to the surface. Koryaksky volcano was mostly active in the early Holocene when Avachinsky volcano was quiet. Koryaksky tephras had a relatively constant bulk medium-K andesitic composition during the Holocene.
Thanks to characteristic compositions, high frequency, and well-constrained ages, the tephras of Avachinsky and Koryaksky volcanoes can be used for high resolution dating of local sediments. Some eruptions of Avachinsky volcano reached volcanic explosivity index (VEI) 5 and produced widely dispersed tephras. These eruptions could have had global environmental effects, and their tephras can be used for the correlation of very disparate sedimentary archives.
Some Avachinsky and Koryaksky eruptions were closely spaced in time. Their tephras are however easily distinguished by their, respectively, low-K and medium-K compositions and by different trace element patterns, which imply compositionally different sources in the mantle wedge. We interpret this difference to reflect the increasing slab surface temperature and transition of slab component from a relatively low-temperature fluid-like phase under Avachinsky volcano to more high-temperature and solute-rich supercritical fluid or melt under Koryaksky volcano. The transition appears to be very sharp in Kamchatka, causing a large compositional shift in magmas just behind the volcanic front.
... The Kamchatka Peninsula is a complex geological region influenced by the subduction of the Pacific plate and Emperor Sea Mounts beneath the Okhotsk Plate ( Churikova et al., 2007;Ponomareva et al., 2007aPonomareva et al., , 2007b). The southeast part of the peninsula, referred to as the Eastern Volcanic Front (EVF), is affected by the subducting Pacific plate, and dis- plays similar composition to volcanoes in the Kuril island chain to the south of the peninsula ( Ishikawa et al., 2001;Ponomareva et al., 2007b). ...
Volcanic eruptions represent a significant source of atmospheric aerosols and can display local, regional and global effects, impacting earth systems and human populations. In order to assess the relative impacts of these events, accurate plume injection altitude measurements are needed. In this work, volcanic plumes generated from seven Kamchatka Peninsula volcanoes (Shiveluch, Kliuchevskoi, Bezymianny, Tolbachik, Kizimen, Karymsky and Zhupanovsky), were identified using over 16 years of Multi-angle Imaging SpectroRadiometer (MISR) measurements. Eighty-eight volcanic plumes were observed by MISR, capturing 3–25% of reported events at individual volcanoes. Retrievals were most successful where eruptive events persisted over a period of weeks to months. Compared with existing ground and airborne observations, and alternative satellite-based reports compiled by the Global Volcanism Program (GVP), MISR plume height retrievals show general consistency; the comparison reports appear to be skewed towards the region of highest concentration observed in MISR-constrained plume vertical extent. The report observations display less discrepancy with MISR toward the end of the analysis period (2013–2016), with improvements in the suborbital data likely the result of the deployment of new instrumentation. Conversely, the general consistency of MISR plume heights with conventionally reported observations supports the use of MISR in the ongoing assessment of volcanic activity globally, especially where ground-based observations are unavailable. Differences between the northern (Shiveluch, Kliuchevskoi, Bezymianny and Tolbachik) and southern (Kizimen, Karymsky and Zhupanovsky) volcanoes broadly corresponding to the Central Kamchatka Depression (CKD) and Eastern Volcanic Front (EVF) geological sub-regions of Kamchatka, respectively, are distinguished by varying magma composition. For example, by comparison with reanalysis-model simulations of local meteorological conditions, CKD plumes were generally less constrained by mid-tropospheric (< 6 km) layers of vertical stability above the boundary layer, suggesting that these eruptions were more energetic than those in the EVF region.
... This approach could be applied at similar volcanoes such as the highly active Merapi volcano (Indonesia), where older pyroclastic sequences hold a fuller eruptive history than could be gleaned from historical records (Andreastuti et al., 2000;Voight et al., 2000;Gertisser et al., 2012), or for example at the San Martin volcano within the Tuxtla Volcanic Field (Mexico), where rapid weathering blurs preservation of isolated or individual tephra units (Espíndola et al., 2010). Another well-known example is the andesitic Shiveluch volcano in Kamchatka, which has produced numerous compositionally similar Holocene tephras and complex proximal stratigraphic sequences (Ponomareva et al., 2007(Ponomareva et al., , 2011(Ponomareva et al., , 2015. ...
In this study, geochemical fingerprinting of glass shards and titanomagnetite phenocrysts was used to match twenty complex pyroclastic deposits from the flanks of Mt. Taranaki to major tephra fall “marker beds” in medial and distal deposition sites. These correlations hinged upon identifying time-bound compositional changes (a chemostratigraphy) in distal Taranaki tephra-fall sequences preserved in lake and peat sediment records around the volcano. The current work shows that previous soil-stratigraphy based studies led to miscorrelations, because they relied upon radiocarbon dates, a “counting back” approach, and an underestimate of the number of eruptions that actually occurred in any time frame. The new tephrostratigraphy proposed at Mt. Taranaki resulted from stratigraphic rearranging of several earlier-defined units. Some tephra units are older than previously determined (e.g., Waipuku, Tariki, and Mangatoki; ~ 6 to 9 cal ka BP), while one of the most prominent Taranaki marker tephra deposit, the Korito, is shown to lie stratigraphically above a widespread rhyolitic marker bed from Taupo volcano, the Stent Tephra (also known as unit Q; ~ 4.3 cal ka BP). Pyroclastic tephra deposits previously dated between ~ 6 to 4 cal ka BP at a key tephra section, c. 40 km NE of Mt. Taranaki's summit, were misidentified and are now shown to comprise new marker tephra deposits, including the Kokowai (~ 4.7 cal ka BP), which is a prominent marker horizon on the eastern flanks of the volcano. A new local proximal stratigraphy for < 5 cal ka BP tephra units can be well correlated to tephra layers within distal lake and peat sequences, but the differences between the two records indicates an overall larger number of eruptions have occurred at this volcano than previously thought. This study additionally demonstrates the utility of titanomagnetite chemistry for discrimination and correlation of groups or sequences of tephra deposits – even if unique compositions cannot be identified.
... We used an olivine CaO content of 0.073% from grain #10 (sample 00K15; IGSN: IEMAX0003), which is the minimum CaO content occurring at the interface of the core and rim (Fig. 5); the Mg number is 92.5. The parental magma was constrained by adding olivine incrementally to lava sample 00K15 (3600 BP mafic eruption) from Ponomareva et al. (2007) (see also sample K1-18B in Gorbach & Portnyagin, 2011). The parental magma contains 7.7 to 7.9% CaO and 13.4 to 14.5% MgO (Table A3), and 6.3% H 2 O, the highest we have estimated for arcs (Table A3). ...
... We investigated tephra samples collected from the lower 5 meters of this section, below a thick (0.5 m) layer of Klyuchevskoy cinders (so called "Upper cinders") dated as around 6 ky 14 C and related to the beginning of intensive construction of the Klyuchevskoy volcanic cone [1]. Dating of rocks in the section was performed by interpolation of age data between recognized regional marker cinder layers of known age [1,2]. The age of mafic layers was estimated to be between 6.8 and ~11.3 ky cal. ...
... respectively (Tables 1 and 2; Braitseva et al., 1997). Ages of all five of the marker tephras were refined based on numerous 14 C dates (Braitseva et al., 1997;Bazanova and Pevzner, 2001;Ponomareva et al., 2007b;Ponomareva et al., 2015). New and old marker layer codes and ages for these marker layers are presented in Table 1. ...
... A detailed tephrostratigraphical framework for Kamchatka has previously been established on the basis of extensive visible tephra layers, all of which derive from Kamchatkan volcanic systems (e.g. Braitseva et al., 1992Braitseva et al., , 1997Ponomareva et al., 2007). Visible Kamchatkan tephra beds have aided the dating of palaeoenvironmental change on the Peninsula (e.g. ...
... Kamchatka is one of the world's most volcanically active regions, periods of active eruptions occurred in the late Pleistocene between 45-39 000 years ago and between 30-25 000 years ago with an additional period of enhanced activity in the early to mid-Holocene between 9500-7000 years BP (Ponomareva et al. 2007). The Pacific Plate is actively subducting beneath the Kamchatka Peninsula at about 80-100 mm per year resulting in three distinct volcanic arcs; the nearly extinct Sredinny Range, the active Eastern Volcanic Front and the very active Central Kamchatka Depression (Nikulin et al. 2012). ...
This paper briefly reviews the physical and human geography of the Kamchatka region and summarises previous research on Holocene climate dynamics. We provide context for the rest of the Special Issue of the Journal Global and Planetary Change entitled ‘Holocene climate change in Kamchatka’, the primary focus of which is the use of lake sediment records for palaeoclimatic inferences. In this paper an additional perspective from ongoing tree ring, ice core and borehole temperature reconstructions illustrates that The Kamchatka region is rich in paleoclimatic proxies. The period of the last 200 years is sufficiently covered by the proxy information, including reconstructions with annual resolution. In this period the tree-rings, ice cores, boreholes, and glacier fluctuations recorded a 1°C warming and a general glacier retreat, i.e. the transition from the Little Ice Age climate to the modern one. Although the proxies have different resolution, accuracy and seasonality in general they demonstrate a coherent picture of environmental changes in the last two centuries. The tree ring and ice core records are up to four-six hundred years long and they provide information on annual to decadal variability of summer temperature, accumulation processes, volcanic eruptions and lahar activity.
... There are also numerous explosive volcanic fields in Japan and Kamchatka peninsula during this period, however, these calcalkaline volcanoes affected mainly by subduction related processes (e.g. Aoki and Machida, 2006;Ponomareva et al., 2007;Philip et al., 2011) can be excluded as a possible source for this tephra because of distinct different glass geochemistry (Fig. 4 A). The intracontinental characterized tephra from Udokan volcanic field also can be ruled out as relative small eruptions, different eruption timings and long distance to LVF (Ivanov et al., 2011). ...
The Changbaishan Millennium eruption (~ AD 940 s) produced a widely distributed tephra layer around northeast Asia. This tephra layer serves as a marker bed in Greenland ice cores and in marine, lake, archaeological and tsunami sediments in Japan and the surrounding region. However, little attention has been paid to the widespread sediments west of Changbaishan volcano. Here we present new stratigraphic, geochemical, varve chronology, and 14C geochronological data from the varved sediments in Lake Sihailongwan, Longgang volcanic field, Northeast China, extending the westerly margin of this eruption. The distinctive geochemical characteristic of volcanic glass (ranging from trachyte to rhyolite), similar to those of proximal and distal tephra, confirmed the occurrence of Changbaishan Millennium eruption ash in the lake, illustrating the westward dispersal fan of the ash deposits. The position of the peak concentration of glass shards of this tephra was dated to 953 ± 37 AD by varve chronology, and the radiocarbon samples immediately above this tephra gave a date of 940–1020 AD, overlapping the most recent ages for this eruption. The occurrence of Changbaishan Millennium eruption ash in this lake enables a direct and precise synchronization with other high-resolution archives in Northeast Asia, such as maar lakes and peat and marine sediments, thus providing an isochronous marker for a range of sedimentary contexts.
... Уникальная геодинамическая позиция вулкана Шивелуч, геохимическая специфика его пород и аномально высокая продуктивность делает этот объект исключительно интересным для проведения реконструкции магматической эволюции и определения генетической природы спектра пород вулкана. Продукты голоценового периода активности вулкана детально изучены [Ponomareva et al., 2007] и геохимически охарактеризованы [Волынец 1997, 2000Portnyagin et al., 2007]. Данные по позднеплейстоценовому этапу формирования вулкана достаточно ограничены [Меняйлов, 1955; Мелекесцев и др., 1991]. ...
1991], а по количеству вынесенных на поверхность андезитов не имеет аналогов среди четвертичных вулканов полуострова. По мнению многих исследователей, высокая продуктивность вулкана является отражением специфики глубинных процессов в зоне сочленения Курило-Камчатской и Алеутской островных дуг. Продукты современных извержений вулкана представлены магнезиальными андезитами [Волынец, 1997], которые имеют высокие концентрации Sr, Ba, низкие концентрации тяжелых редкоземельных элементов при высоких отношениях La/Yb и низких FeO/MgO. Подобные геохимические параметры могут свидетельствовать о плавлении субдуцируемой океанической коры в районе Камчатско-Алеутского сочленения [Волынец и др., 2000; Yogodzinsky et al., 2001]. Уникальная геодинамическая позиция вулкана Шивелуч, геохимическая специфика его пород и аномально высокая продуктивность делает этот объект исключительно интересным для проведения реконструкции магматической эволюции и определения генетической природы спектра пород вулкана. Продукты голоценового периода активности вулкана детально изучены [Ponomareva et al., 2007] и геохимически охарактеризованы [Волынец 1997, 2000; Portnyagin et al., 2007]. Данные по позднеплейстоценовому этапу формирования вулкана достаточно ограничены [Меняйлов, 1955; Мелекесцев и др., 1991]. В сообщении впервые представлена геолого-геохимическая характеристика пород наименее изученной начальной фазы деятельности вулкана и показано сравнение с продуктами современных извержений. Рис. 1. Вулкан Шивелуч и его главные структурные элементы. Красная пунктирная линия показывает границу пирокластической толщи начальной фазы деятельности вулкана и лавового комплекса Старого Шивелуча. Красные стрелки маркируют позицию лавовой пачки Ol-Cpx-Pl андезибазальтов. В строении вулкана выделяются два главных структурных элемента – верхнеплейстоценовая постройка Старого Шивелуча и активный в голоцене Молодой Шивелуч [Мелекесцев и др., 1991] Начальной фазе деятельности (НФД) вулкана отвечают грубообломочные пирокластические отложения, которые формируют не менее 60% объeма постройки Старого Шивелуча. В различных секторах вулкана преобладают агломератовые туфы роговообманковых и пироксен-роговообманковых андезитов. Отложения грубо-стратифицированы, иногда слабо сортированы и представлены крупнообломочным материалом (угловатые обломки 20-40 см и до 1 м), погруженным в рыхлый или слаболитифицированный матрикс песчано-гравийной размерности. По аналогии с продуктами современных извержений эти отложения можно идентифицировать как отложения пеплово-глыбовых пирокластических потоков. Важными чертами сходства современных и ранних пирокластических отложений являются значительные площади распространения и субгоризонтальное залегание.
... [9] The Kamchatsky Peninsula ( Figure 2) is composed of a broad variety of rocks and sediments ranging in age from Early Cretaceous to Holocene [Tsukanov, 1991], of which we focus on sequences of later Pleistocene marine terraces and present relevant data back to the early Pleistocene. The Cretaceous to lower Pleistocene formations are locally overlain with angular discordance by middle and upper Pleistocene and also Holocene soil-tephra sequences [Pevzner et al., 1997;Ponomorova et al., 2007] and shallow-marine sediments. The upper Pliocene to lower Quaternary Olkhovskaya Formation caps large portions of the peninsula and is characterized by coarse-grained, semiconsolidated, marine sediments [Basilyan and Bylinskaya, 1997]. ...
[1] At the NW corner of the Pacific region, just south of the Kamchatsky Peninsula, the northern tip of the Pacific plate subduction and associated volcanic arc interacts with the western end of the Aleutian-Komandorsky dextral transform plate boundary and associated arc. Study of both Holocene and Pleistocene sequences of uplifted marine terraces and also of fluvial drainage patterns on the Kamchatsky Peninsula allows us to highlight active tectonics produced by complex plate interaction. Our results show that the central eastern coast of the peninsula is currently divided into four different zones consisting in uplifted blocks associated with various uplift rates in front of a fold-and-thrust zone to the west. Our main tectonic benchmark—the altitude of the shoreline correlated to the Last Interglacial Maximum (Marine Isotopic Stage 5e)—yields late Pleistocene uplift rates ranging from 0.2 to 2.74 mm/yr. One of the main active faults bounding the coastal blocks is dextral and is interpreted as a prolongation of an offshore fault of the Aleutian-Komandorsky dextral transform plate boundary. We suggest that structures on the Kamchatsky Peninsula accommodate a part of the transform motion, but that mainly, the arc-continent collision of the Aleutian arc against Kamchatka produces a “bulldozer” effect on the Kamchatsky Peninsula.
... Glass compositions of K, QUB-1437, QUB-1819a, and QUB-1819b are comparable to those of published proximal and distal data produced by the Millennium eruption and clearly distinct from broadly contemporary eruptions with similar compositions, such as (1) the Jala pumice of Volcán Ceboruco, Mexico [Gardner and Tait, 2000], (2) Hekla A.D. 1104 (data from http://www.tephrabase.org/; sources Boygle [1994]; Larsen et al. [1999]), (3) Holocene tephra of Shiveluch volcano, Russia [Ponomareva et al., 2007], and (4) widespread Quaternary tephra around Japan [Aoki and Machida, 2006] and the dacitic Glass B in GISP2 at A.D. 938 ± 4 [Zielinski et al., 1995] (envelopes represent distribution of published data points). Published B-Tm and TC data are from Machida et al. [1990]; Zou et al. [2010], and Hughes et al. [2013], and QUB-1437 data are from Coulter et al. [2012]. ...
Major volcanic eruptions can impact on global climate by injecting large quantities of aerosols and ash into the atmosphere that alter the radiative balance and chemical equilibrium of the stratosphere. The Millennium eruption of Tianchi (Paektu), China/North Korea, was one of the largest Late Holocene eruptions. Uncertainty about the precise timing of the eruption has hindered the recognition of its climate impact in palaeoclimate and historical records. Here we report the compelling identification of the eruption's volcanic signal in Greenland ice cores through the association of geochemically-characterized volcanic glass, represented in by bimodal populations that compare with proximal material from the source eruption. The eruption most probably occurred in the AD 940 s, seven years after the Eldgjá eruption on Iceland. We examine the eruption's potential for climate forcing using the sulfate records from the ice-cores and conclude that it was unlikely to have had a global or extra-regional impact.
Oxygen fugacity is an important but difficult parameter to constrain for primitive arc magmas. In this study, the partitioning behavior of Fe3+/Fe2+ between amphibole and glass synthesized in piston-cylinder and cold-seal apparatus experiments is developed as an oxybarometer, applicable to magmas ranging from basaltic to dacitic composition. The partitioning of Fe2+ is strongly dependent on melt polymerization; the relative compatibility of Fe2+ in amphibole decreases with increasing polymerization. The Fe2+/Mg distribution coefficient between amphibole and melt is a relatively constant value across all compositions and is, on average, 0.27. The amphibole oxybarometer is applied to amphibole in mafic enclaves, cumulates, and basaltic tephra erupted from Shiveluch volcano in Kamchatka with measured Fe3+/FeTotal. An average Fe3+/Fe2+ amphibole-glass distribution coefficient for basalt is used to convert the Fe3+/FeTotal of amphibole in samples from Shiveluch to magmatic oxygen fugacity relative to NNO. The fO2 of primitive melts at the volcano is approximately NNO+2 and is faithfully recorded in amphibole from an amphibole-rich cumulate and the basaltic tephra. Apparently, higher fO2 recorded by amphibole in mafic enclaves likely results from partial dehydrogenation of amphibole during residence in a shallow andesite storage region. We identify three pulses of mafic magma recharge within two weeks of, a month before, and two to three months before the eruption and find that, at each of these times, the host andesite was recharged by at least two magmas at varying stages of differentiation. Application of the amphibole oxybarometer not only gives insight into magmatic fO2 but also potentially details of shallow magmatic processes.
Find the centre of the eruption of basalts on the volcano Shiveluch
Two of the largest known historic block-and-ash flow (BAF) fields are located on Shiveluch volcano, Kamchatka. The deposits were produced during retrogressive and pulsatory dome collapse events that occurred over 6-9 hour-long eruptions on 27-28 February 2005 and 27 October 2010. The BAFs that were produced by these partial dome collapse events extend up to 19 km from the dome and inundate areas of 24.1 and 22.3 km2. We used satellite and field data to investigate the surface morphology of the BAF deposits and their impact on the surrounding area. The deposit surfaces contain overlapping lobate deposits, compaction ridges, levees and channel morphologies, degassing structures, abundant large dome blocks, and large areas of syn- or immediately-post-depositional remobilization, as shown by bench scallops and arcuate scarps. The dome-collapse events produced flows with two components: the dense block-and-ash component of the flows, and the associated dilute pyroclastic surges. The surge components traveled beyond the main flow and killed vegetation to distances of nearly 300 m. The 2005 dome collapse event produced a BAF that extended 17.8 km from the dome and emplaced a large fan deposit and associated surge, which destroyed an area of forest 10 km2 in size. The October 2010 event also produced a large fan deposit with a distal channelized deposit that extended an additional 5.4 km beyond the main 2010 fan for a total distance from the dome of 19 km. Since deposition, fluvial erosion and deposition produced large areas comprised of dendritic and braided channel deposits. The surface morphology of the deposits as revealed in satellite imagery and observed in stratigraphic sections give insight into the pulsatory nature of the dome collapse events, the final moments of deposition, and the subsequent erosion of the deposits. Preservation of the deposits is exceptional due to the high-latitude location, where snow-cover is present for much of the year and erosion is limited. This detailed study of the Shiveluch deposits provides rare insight into the processes responsible for generation of large and long run-out dome-collapse BAFs in both channelized and non-channelized environments.
It is shown that Shiveluch, which consists of several volcanic edifices that stand in one area and in part overlie each other, is a long-lived volcanic massif with a complex structure. The available data on the morphology of the edifice, age, rock compositions, primary melts, and types of eruptive activity were used to identify structurally-temporal units (STUs) in the Shiveluch volcanic massif. It was found that the generation of different-age STUs was due to the activity of at least four magma chambers with different parameters. The durations of the individual chambers were determined. The activities of these chambers were initiated and came to an end nearly instantaneously because of major collapse episodes in the edifice of the massif due to high-magnitude earthquakes.
Complex core-rim zoning of Mg-Fe-Ni-Ca-Cr-Al-P in high-Mg olivine crystals from a tuff ring of Shiveluch volcano, Kamchatka, enables reconstruction of the entire olivine crystallization history from mantle conditions to eruption. Bell-shaped Fo86–92 and Ni profiles in crystal cores were formed by diffusion after mixing with evolved magma. Diffusion proceeded to the centres of crystals and completely equilibrated Fo and Ni in some crystals. Diffusion times extracted from Fo and Ni core profiles range from 100 to 2000 days. During subsequent mixing with mafic mantle-equilibrated melt, the cores were partially dissolved and overgrown by Fo90 olivine. Times extracted from Fo and Ni diffusion profiles across the resorption interface between the core and its overgrowth range within 1–10 days, which corresponds to the time of magma ascent to the surface. The overgrowth shows identical smooth Fo-Ni decreasing zoning patterns for all crystals towards the margin, indicating that all crystals shared the same growth history after last mixing event prior to eruption. At the same time, Ca, and to an even greater extent Cr, Al, and P have oscillatory growth patterns in the crystals overgrowth. Our data show that magma ascent can be extremely short during maar/tuff ring eruption.
В голоценовое время наибольшая вулканическая активность на Камчатском полуострове проявлялась в пределах Ключевской группы вулканов (КГВ). КГВ расположена в северной части Центральной Камчатской депрессии (ЦКД) на плато высотой около 1000 м и состоит из тринадцати вулканов, породы которых значительно отличаются друг от друга по петрографии, минералогии, содержанию кремнезема, по макро- и микроэлементному составу. Вопрос разнообразия вулканических пород является одним из наиболее острых среди вопросов магмообразования не только в КГВ, но и во всей Камчатской зоне субдукции. За последние десятилетия в отечественной и зарубежной печати появилось большое число работ, посвященных изучению пород КГВ, однако в большей части публикаций рассматриваются продукты исторических и голоценовых извержений. Более того, породы некоторых объектов КГВ не изучались вообще, некоторые объекты были обследованы в середине XX в., и об их породах известны лишь грубые петрохимические характеристики. Таким образом, геохимические и возрастные взаимоотношения вулканов Ключевской группы во многом остаются неясными. Вряд ли возможно понять эволюцию магматического вещества в пределах КГВ в пространстве и времени без рассмотрения вулканизма, происходившего в доголоценовое время как для каждого вулкана, так и для всего региона в целом.
Малоизученными объектами КГВ являются не только такие ныне потухшие вулканы, как Удины Сопки, Зимины Сопки и Горный Зуб, но и среднеплейстоцен-голоценовые вулканы Острый Толбачик и относящийся к активным Плоский Толбачик, на склонах которого в течение последних 10 тыс. лет активно работает зона моногенных шлаковых и шлаколавовых конусов, извергающих породы различного химического состава. Геологическая история формирования Толбачинского массива с возрастным и вещественным разделением вулканических проявлений в голоцене, описана во многих работах после Большого трещинного Толбачинского извержения 1975–1976 гг. (БТТИ). Голоценовым и историческим извержениям моногенных конусов и вулкана Плоский Толбачик посвящено более 900 российских и зарубежных публикаций. В то же время петролого-геохимическая информация по плейстоценовому периоду развития Толбачинского массива практически отсутствует.
В семидесятых годах прошлого века была составлена геологическая карта Толбачинского массива, дано описание петрографического и минерального состава пород, а также получены первые химические анализы пород на макроэлементы. Несмотря на огромный интерес к Большому трещинному Толбачинскому извержению 1975–1976 гг. и многочисленные публикации о разнообразном составе его продуктов, геохимические и изотопные исследования самих стратовулканов не проводились, и их вещественная эволюция и связь с зоной моногенного вулканизма до сих пор оставались неизвестными. Только после извержения 2012—2013 гг. появилось несколько работ, посвященных Толбачинскому массиву.
Для определения мантийных и флюидных источников пород Толбачинского вулканического массива и выяснения взаимоотношений пород его разновозрастных комплексов в настоящей работе представлены геологические, петрографические, петрохимические, геохимические, изотопные данные, а также данные K-Ar датирования. В главе использована представительная коллекция из 155 образцов, собранная со всех перечисленных выше объектов Толбачинского массива, включая моногенные конусы различных возрастных групп, вплоть до последнего извержения 2012–2013 гг. Кроме того, были исследованы образцы горы Поворотной, расположенной в 8 км к северо-востоку от Плоского Толбачика, а также образцы лав основания КГВ, опробованных в обнажениях долины р. Студеной. Комплексное изучение Толбачинского вулканического массива позволило не только получить информацию по петрологии и геохимии самого массива, но также понять взаимоотношения пород массива с соседними вулканическими проявлениями в КГВ.
New paleomagnetic determinations satisfying the up-to-date methodical and instrumental standards of paleomagnetic studies are obtained from the lava flows and volcanic ash of the Northern Group of Kamchatka volcanoes. In the past 4000 years, 12 stratigraphic levels with tephrostratigraphic ages are explored. The obtained directions of the geomagnetic field fill a gap in the data on the secular variation for northeastern Asia and can be used for developing global models. Besides, a promising outlook for the use of the variations of the geomagnetic field for the regional correlation of volcanic events is demonstrated.
Geochemically fingerprinted widespread tephra layers serve as excellent marker horizons which can directly link and synchronize disparate sedimentary archives and be used for dating various deposits related to climate shifts, faulting events, tsunami, and human occupation. In addition, tephras represent records of explosive volcanic activity and permit assessment of regional ashfall hazard. In this paper we report a detailed Holocene tephrochronological model developed for the Kamchatsky Peninsula region of eastern Kamchatka (NW Pacific) based on ∼2800 new electron microprobe analyses of single glass shards from tephra samples collected in the area as well as on previously published data. Tephra ages are modeled based on a compilation of 223 14C dates, including published dates for Shiveluch proximal tephra sequence and regional marker tephras; new AMS 14C dates; and modeled calibrated ages from the Krutoberegovo key site. The main source volcanoes for tephra in the region are Shiveluch and Kliuchevskoi located 60–100 km to the west. In addition, local tephra sequences contain two tephras from the Plosky volcanic massif and three regional marker tephras from Ksudach and Avachinsky volcanoes located in the Eastern volcanic front of Kamchatka. This tephrochronological framework contributes to the combined history of environmental change, tectonic events, and volcanic impact in the study area and farther afield. This study is another step in the construction of the Kamchatka-wide Holocene tephrochronological framework under the same methodological umbrella. Our dataset provides a research reference for tephra and cryptotephra studies in the northwest Pacific, the Bering Sea, and North America.
We investigated chironomid assemblages of a well-dated sediment core from a small seepage lake situated at the eastern slope of the Central Kamchatka Mountain Chain, Far East Russia. The chironomid fauna of the investigated Sigrid Lake is dominated by littoral taxa that are sensitive to fluctuations of the water level. Two groups of taxa interchangeably dominate the record responding to the changes in the lake environment during the past 2800 years. The first group of littoral phytophilic taxa includes Psectrocladius sordidellus-type, Corynoneura arctica-type and Dicrotendipes nervosus-type. The abundances of the taxa from this group have the strongest influence on the variations of PCA 1, and these taxa mostly correspond to low water levels, moderate temperatures and slightly acidified conditions. The second group of taxa includes Microtendipes pedellus-type, Tanytarsus lugens-type, and Tanytarsus pallidicornis-type. The variations in the abundances of these taxa, and especially of M. pedellus-type, are in accordance with PCA 2 and correspond to the higher water level in the lake, more oligotrophic and neutral pH conditions. Water depths (WD) were reconstructed, using a modern chironomid-based temperature and water depth calibration data set (training set) and inference model from East Siberia (Nazarova et al., 2011). Mean July air temperatures (T July) were inferred using a chironomid-based temperature inference model based on a modern calibration data set for the Far East (Nazarova et al., 2015). The application of transfer functions resulted in reconstructed T July fluctuations of approximately 3 °C over the last 2800 years. Low temperatures (11.0–12.0 °C) were reconstructed for the periods between ca 1700 and 1500 cal yr BP (corresponding to the Kofun cold stage) and between ca 1200 and 150 cal yr BP (partly corresponding to the Little Ice Age [LIA]). Warm periods (modern T July or higher) were reconstructed for the periods between ca 2700 and 1800 cal yr BP, 1500 and 1300 cal yr BP and after 150 cal yr BP. WD reconstruction revealed that the lake level was lower than its present level at the beginning of the record between ca 2600 and 2300 cal yr BP and ca 550 cal yr BP. Between ca 2300 and 700 cal yr BP as well as between 450 and 150 cal yr BP, the lake level was higher than it is today, most probably reflecting more humid conditions.
We advance our own definitions of the following terms: catastrophic volcanic eruption (CE), catastrophic supereruption (CSE), different-rank and different-type episodes and phases of volcanic catastrophism (VC). All eruptions are subdivided into three classes according to the volume and weight of the erupted and transported (juvenile and resurgent) material, whatever its chemical composition: class I (>0.5 km3), class II (≥5 km3), and class III, or supereruptions (>50 km3). We characterize the types and varieties of CEs and CSEs, with most of these being the main components of identified VC episodes and phases. The primary phenomena to be considered include catastrophic events of the 19th to 21st centuries, not only in the Kuril–Kamchatka region, but also in other volcanic areas. These events have been studied in detail by modern methods and can serve as approximate models to reconstruct similar past events, especially regarding their dynamics, productivity, and catastrophic impact.
Shiveluch (N 56°38’, E 161°19’) is one of the most active volcanoes in Kamchatka. The eruptions of this volcano result in environmental damage caused by debris avalanches, hot pyroclastic flows, tephra falls and lahars. The last major eruption of Shiveluch occurred in 2005; it was accompanied by a pumice fall and a large pyroclastic flow.
A pollen record, obtained from sediments of Lake Sokoch in mountain interior of the Kamchatka Peninsula, covers the last ca. 9600 years (all ages are given in calibrated years BP). Variations in local components, including pollen, spores and non-pollen palynomorphs, and related changes in sedimentation document the lake development from initially seepage and shallow basin to deeper lake during the mid Holocene and then to the hydrologically open system during the late Holocene. The studies of volcanic ashes from the lake sediment core show their complex depositional histories.
Lake Sokoch occupies a former proglacial basin between two terminal moraines of the LGM time. The undated basal part of record before ca. 9600 year BP, however, does not reflect properly cold conditions. At that time, although shrublands and tundra dominated, stone birch and white birch forests have already settled in surroundings; the presence of alder woodland indicates wet and maritime-like climate. The subsequent forest advance suggesting warmer conditions was interrupted by the ca. 8000–7600 year BP spell of cooler climate. The following culmination of warmth is bracketed by the evidence of the first maximal forest extent between ca. 7400 and 5100 year BP. During that time, dramatic retreat of alder forest suggests a turn from maritime-like to more continental climate conditions. The cool and wet pulse after ca. 5100 year BP was pronounced as forests retreat while shrublands, meadows and bogs extended. An expansion of white birch forest since ca. 3500 year BP reflected the onset of drier climate, strengthening continentality and seasonal contrast. The second maximum of forests dominated by both stone and white birches occurred between ca. 2200 and 1700 year BP and indicated warming in association with relatively dry and increasingly continental climate. The following period was wetter and cooler, and minor outbreak of alder forest around ca. 1500 year BP suggests a short-term return of maritime-like conditions. Since ca. 1300 year BP forests retreated and replaced by shrublands, tundra and bogs, pointing to cool and wet climate and likely increased back continentality. A prominent re-advance of stone birch forest shown atop the record, most probably reflects recent warming trend.
The reconstructed cool periods correlate well with Holocene glacial advances in neighboring mountain areas and with the tree ring and ice core records from the Central Kamchatka Depression. The Lake Sokoch pollen record, being consistent with the previously obtained regional paleoclimatic data, yet contributes new detailed information, especially for the late Holocene.
Вулкан Шивелуч, расположенный в северной части Центральной Камчатской депрессии, – один из самых активных и наиболее детально изученных вулканов Камчатки. Вулкан начал формироваться 60-70 тыс. лет назад сначала как пирокластический, затем развивался как лавовый стратовулкан (Старый Шивелуч); современный эруптивный аппарат (Молодой Шивелуч) возник около 30 тыс. л.н. в крупной кальдере, открытой на юг.
Продукты извержений, как Старого, так и Молодого Шивелуча в основном представлены магнезиальными средне-калиевыми андезитами и андезибазальтами c SiO2 ≥ 55%, базальты же и базальт-андезибазальты с SiO2 ≤ 54% встречаются крайне редко. Поэтому всякие находки материала основного состава на этом вулкане представляют особый интерес. В голоценовых почвенно-пирокластических разрезах всех секторов подножия вулкана было отмечено всего два слоя тефры высокомагнезиальных базальтов, которые, согласно тефрохронологическим данным, имеют возраст 3600 14C лет и 7600 14C лет. Продукты обоих извержений представлены вулканическими песками, гравием, лапилли и тонкими пеплами. Тефры были детально изучены, и по характеру их распространения и стратификации было сделано предположение, что центры обоих извержений располагались в прикратерной части постройки Молодого Шивелуча. Эти тефры схожи между собой по ряду минералогических и геохимических и признаков: высокомагнезиальные темноцветные минералы близкого состава, высокий магнезиальный номер пород, а также высокие концентрации Cr и Ni. Тем не менее, они имеют и заметные различия: тефра извержения 7600 14C л.н. характеризуется обычным набором минералов – Ol+Cpx+Pl – и является средне-калиевой, в то время как тефра извержения 3600 14C л.н., кроме упомянутых минералов, содержит небольшие количества флогопита и амфибол, преобладающий в породе и составляющий 15-20% вкрапленников, она относится к высоко-калиевой серии и обогащена по Ba и Rb. Следует отметить, что в коренном залегании голоценовые базальты извержений как 3600, так и 7600 14C л.н., до сих пор обнаружены не были.
Detailed data are discussed on the rate of Holocene horizontal and vertical movements along a
fault in the southeastern Kamchatsky Peninsula, which is situated between the converging Aleutian and Kamchatka island arcs. The fault is the northern boundary of the block invading into the peninsula under pressure of the Komandorsky Block of the Aleutian arc. The rate of right-lateral slip along the fault was increasing in the Holocene and reached 18–19 mm/yr over the last 2000 years and 20 mm/yr by contemporary time. Comparison of these estimates with those that follow from offsets of older rocks also indicates acceleration of horizontal movements along the fault from the early Quaternary to the present. The results obtained from rates of GPS station migration show that about half the rate of the northwestern drift of the Komandorsky Block is consumed for movement of the block of the southern side of the fault. The remainder of movement of the Komandorsky Block is consumed for movements (probably, underthrusting) at the eastern continental slope of the Kamchatsky Peninsula.
The Shiveluch volcanic massif is one of the largest centers of andesite volcanism in Kamchatka. The paper reports pioneering data on inclusions in 24 samples of pyroclastic rocks characterizing principal evolutionary stages and episodes of the three structural–age complexes composing the massif. The rocks composing these complexes range from andesite to basalt. Data obtained by studying 145 inclusions of natural quenched glasses in minerals from the volcanic rocks of various age make it possible to distinguish three major melt types which gave rise to the whole spectrum of the pyroclastic rocks of the Shiveluch volcanic massif. These melts corresponded to picrobasalt and tephrobasanite (42–34 wt % SiO2, 7 wt % MgO, and up to 1.9 wt % K2O), dacite and trachydacite (59–66 wt % SiO2, 1.6–2.6 wt %, and up to 3 wt % K2O), and rhyolite (69–74 wt % SiO2, 0.2–0.5 wt % MgO, and up to 3.7 wt % K2O). The trace-element composition of the melts and their water contents are determined. All of the melt types had low Nb concentrations and were relatively rich in elements mobile in fluid (up to 50 ppm Rb, >700 ppm Ba, and up to 2–3 ppm Th) but were differently depleted in HREE (La/Yb ranges from 3 to 14) and enriched in HFSE. Along with the melts, the mineralogy and petrography of the rocks were examined. The rocks show evidence of hybridism, which should have played an important role in producing andesite of the volcano. The evolutionary history of the volcanic massif is reproduced based on tephrochronologic and petrologic data.
The nature of the alteration of basaltic, andesitic and rhyolitic glass of Holocene and Pleistocene age and their physical and chemical environments have been investigated in the ash layers within the cryogenic soils associated with the volcanoes in the central depression of Kamchatka. One of the main factors controlling the alteration of the volcanic glass is their initial chemistry with those of andesitic (SiO2 = 53–65 wt.%) and basaltic (SiO22>65 wt.%) are characterized by opal. Variations in the age of eruption of individual ashes, the amount and nature of the soil water, the depth of the active annual freeze-thawing layer, the thermal conductivity of the weathering soils, do not play a controlling role in the type of weathering products of the ashes but may affect their rates of alteration.
Kamchatsky Peninsula lies within a complex meeting place of tectonic plates, in particular, the orthogonal interaction of the west-moving Komandorsky Island block with mainland Kamchatka. Examining the Holocene history of vertical deformation of marine wave-built terraces along the peninsular coast, we differentiated tectonic blocks undergoing uplift and tilting separated by zones of stable or subsided shorelines. We analyzed 200 excavations along >30 coastal profiles and quantified vertical deformation on single profiles as well as along the coast using paleoshorelines dated with marker tephras. For the past ~2000 yr, the average rates of vertical deformation range from about -1 to +7 mm/yr. Uplift patterns are similar to those detected from historical leveling and from mapping of the stage 5e Quaternary marine terrace (ca. 120 ka). Average vertical deformation in the Holocene is highest for the shortest studied time period, from ca. A.D. 250 to 600, and it is several times faster than rates for marine oxygen isotope stage (MIS) 5e terraces. Vertical displacements observed along the coast are most likely coseismic and probably have included subsidence as well as uplift events. Because subsidence is generally associated with erosion, almost surely more prehistoric large earthquakes occurred than are recorded as topographic steps in these terraces. We suggest that the distribution of coastal uplift and subsidence observed along the Kamchatsky Peninsula coastline is qualitatively explained by the squeezing of the Kamchatsky Peninsula block between the Bering and Okhotsk plates, and the Komandorsky Island block.
Major and trace element and Sr Nd Pb isotopic variations ill mafic volcanic rocks hve been studied in a 220 km transect across the Kamchatka are from the Eastern Volcanic Front, over the Central Kamchatka Depression to the Sredinny Ridge in the back-arc. Thirteen volcanoes and lava fields, from 110 to 400 km above the subducted slab, were sampled. This allows its to characterize spatial variations and the relative amount and composition of the slab fluid involved in magma genesis. Typical Kamchatka arc basalts, normalized for fractionation to 6% MgO. display a strong increase in large ion lithophile, light rare earth and high field strength elements from the arc front to the back-arc. Ba/Zr and Ce/Pb ratios, however, are nearly constant across the arc, which suggests a similar fluid input for Ba and Pb. La/Yb and Nb/Zr- increase from the are front to the back-arc. Rocks from the, Central Kamchatka Depression range in Sr-87/Sr-86 from 0.70334 to 0.70366, but have almost constant Nd isotopic compositions (Nd-141/Nd-144 0.51307-0.51312). This correlates with the highest U/Th ratios in these rocks. Pb-isotopic ratios are mid-ocean ridge basalt (MORB)-like but decrease slightly from the volcanic front to the back-mv. The initial mantle source ranged from N-MORB-like ill the volcanic front and Central Kamchatka Depression to more enriched in the back-arc. This enriched component is similar to all ocean-island basalt (OM) source. Variations in (CaO)(6.0)-(Na2O)(6.0) show that degree of melting decreases fi-om the arc front to the Central Kamchatka Depression and remains constant from there to the Sredinny Ridge. Calculated fluid compositions have a similar trace element pattern across the arc, although minor differences are implied. A model is prevented that quantifies the various mantle components (variably depleted, N-MORB-mantle and enriched OIB-mantle) and the fluid compositions added to this mantle wedge. The amount of fluid added ranges from 0.7 to 2.1%. The degree of melting changes from similar to 20% at the arc front to < 10% below the back-an, region. 77if, xocksfioni volcanoes qj'thc northern part of the Central Kamchatka Depression to the north of the transect considered in this study - are significantly, different in their trace element composition) compared with the other rocks of the transect and their source appear) to have been enriched by a component derived from melting of the edge of the ruptured slab.
The Kamchatka peninsula in Russian East Asia lies at the junction of a transcurrent plate boundary, aligned with the western Aleutian Islands, and a steeply-dipping subduction zone with near-normal convergence. Seismicity patterns and P-wave tomography argue that subducting Pacific lithosphere terminates at the Aleutian junction, and that the downdip extension (>150km depth) of the slab edge is missing. Seismic observables of elastic anisotropy (SKS splitting and Love-Rayleigh scattering) are consistent with asthenospheric strain that rotates from trench-parallel beneath the descending slab to trench-normal beyond its edge. Present-day arc volcanism is concentrated near the slab edge, in the Klyuchevskoy and Sheveluch eruptive centers. Loss of the downdip slab edge, whether from thermo-convective or ductile instability, and subsequent ``slab-window'' mantle return flow is indicated by widespread Quaternary volcanism in the Sredinny range inland of Klyuchevskoy and Sheveluch, as well as the inferred Quaternary uplift of the central Kamchatka depression. The slab beneath Klyuchevskoy has shallower dip (35o) than the subduction zone farther south (55o) suggesting a transient lofting of the slab edge, either from asthenospheric flow or the loss of downdip load. Such lofting may induce pressure-release melting to supply the Klyuchevskoy and Sheveluch eruptive centers. Petrologic indicators of high magma-peridotite equilibrium temperatures, long residence times for the hydrous arc-volcanic component, and weak expression of subducted sediment flux support the lofting hypothesis, and discourage an alternate interpretation in terms of accelerated slab rollback and/or a heightened influx of subducted volatiles. Over the late Cenozoic, the Komandorsky Basin subducted beneath northern Kamchatka and produced arc volcanics in the Sredinny Range. Several lines of evidence suggest the northeast migration of a plate triple junction (North America/Pacific/Komandorsky) along the southern Kamchatka coast in Oligocene-Miocene times. Three ``cape terranes'' (Shipunsky, Kronotsky, Kamchatka) along the coastline are exotic, with geologic similarities to present-day Western Aleutian islands, and may have accreted in a ``caulking-gun'' process as the triple junction migrated NE. The late Cenozoic transfer of arc volcanism from the Sredinny range to the eastern volcanic front of Kamchatka may have been facilitated by the progressive replacement of a shallow-dipping Komandorsky slab with a steeply-dipping Pacific slab.
The ages of most of calderas, large explosive craters and active volcanoes in the Kuril-Kamchatka region have been determined by extensive geological, geomorphological, tephrochronological and isotopic geochronological studies, including more than 600 14C dates. Eight Krakatoa-type and three Hawaiian-type calderas and no less than three large explosive craters formed here during the Holocene. Most of the Late Pleistocene Krakatoa-type calderas were established around 30 000–40 000 years ago. The active volcanoes are geologically very young, with maximum ages of about 40 000–50 000 years. The overwhelming majority of recently active volcanic cones originated at the very end of the Late Pleistocene or in the Holocene. These studies show that all Holocene stratovolcanoes in Kamchatka were emplaced in the Holocene only in the Eastern volcanic belt. Periods of synchronous, intensified Holocene volcanic activity occurred within the time intervals of 7500–7800 and 1300–1800 14C years BP.
Investigation of well-exposed volcaniclastic deposits of Shiveluch volcano indicates that large-scale failures have occurred
at least eight times in its history: approximately 10,000, 5700, 3700, 2600, 1600, 1000, 600 14C BP and 1964 AD. The volcano was stable during the Late Pleistocene, when a large cone was formed (Old Shiveluch), and became
unstable in the Holocene when repetitive collapses of a portion of the edifice (Young Shiveluch) generated debris avalanches.
The transition in stability was connected with a change in composition of the erupting magma (increased SiO2 from ca. 55–56% to 60–62%) that resulted in an abrupt increase of viscosity and the production of lava domes. Each failure
was triggered by a disturbance of the volcanic edifice related to the ascent of a new batch of viscous magma. The failures
occurred before magma intruded into the upper part of the edifice, suggesting that the trigger mechanism was indirectly associated
with magma and involved shaking by a moderate to large volcanic earthquake and/or enhancement of edifice pore pressure due
to pressurised juvenile gas. The failures typically included: (a) a retrogressive landslide involving backward rotation of
slide blocks; (b) fragmentation of the leading blocks and their transformation into a debris avalanche, while the trailing
slide blocks decelerate and soon come to rest; and (c) long-distance runout of the avalanche as a transient wave of debris
with yield strength that glides on a thin weak layer of mixed facies developed at the avalanche base. All the failures of
Young Shiveluch were immediately followed by explosive eruptions that developed along a similar pattern. The slope failure
was the first event, followed by a plinian eruption accompanied by partial fountain collapse and the emplacement of pumice
flows. In several cases the slope failure depressurised the hydrothermal system to cause phreatic explosions that preceded
the magmatic eruption. The collapse-induced plinian eruptions were moderate-sized and ordinary events in the history of the
volcano. No evidence for directed blasts was found associated with any of the slope failures.
Most island-arc magmatism appears to result from the lowering of the melting point of peridotite within the wedge of mantle above subducting slabs owing to the introduction of fluids from the dehydration of subducting oceanic crust. Volcanic rocks interpreted to contain a component of melt (not just a fluid) from the subducting slab itself are uncommon, but possible examples have been recognized in the Aleutian islands, Baja California, Patagonia and elsewhere. The geochemically distinctive rocks from these areas, termed 'adakites, are often associated with subducting plates that are young and warm, and therefore thought to be more prone to melting. But the subducting lithosphere in some adakite locations (such as the Aleutian islands) appears to be too old and hence too cold to melt. This implies either that our interpretation of adakite geochemistry is incorrect, or that our understanding of the tectonic context of adakites is incomplete. Here we present geochemical data from the Kamchatka peninsula and the Aleutian islands that reaffirms the slab-melt interpretation of adakites, but in the tectonic context of the exposure to mantle flow around the edge of a torn subducting plate. We conclude that adakites are likely to form whenever the edge of a subducting plate is warmed or ablated by mantle flow. The use of adakites as tracers for such plate geometry may improve our understanding of magma genesis and thermal structure in a variety of subduction-zone environments.
The junction of the Aleutian Island and the Kamchatka peninsula defines a sharp turn in the boundary of the Pacific and North American plates, terminating the subduction zones of the northwest Pacific. The regional pattern of shear-wave birefringence near the junction indicates that trench-parallel strain follows the seismogenic Benioff zone, but rotates to trench-normal beyond the slab edge. Asthenospheric mantle is inferred to flow around and beneath the disrupted slab edge, and may influence the shallowing dip of the Benioff zone at the Aleutian junction.
The author offers an overview of the complex phenomenon of andesite genesis to help clarify the long-standing problem and to identify profitable areas for future research. It is considered that conventional explanations better account for more of the data than do the more elegantly simple theories produced by plate tectonic theory. -R.A.H.
This paper describes a recent eruption of Shiveluch, the most hazardous andesitic volcano of Kamchatka. The eruptive activity comprised a paroxysmal position, pyroclastic flows, lahars, and ash falls. The growth of a volcanic dome in the crater has been correlated with seismic activity. The consequences of the eruption has been appraised and volcanic hazards assessed. -Journal summary
We discuss results of 14C dates obtained from areas of young volcanoes in Kamchatka. We apply these dates to reconstructing regional volcanic activity during the Holocene. -Authors
Two associations were revealed among the Northern group volcanoes in Kamchatka by study of chemical and isotopic composition of their lavas. The first association includes volcanoes located north of the Kamchatka River, e.g., Shiveluch, Zarechnyi, Kharchinskii volcanoes, and Kharchinskii regional zone of cinder cones. The second association comprises volcanoes located south of this river, e.g., Klyuchevskoi, Ploskie Sopki, Tolbachik, Nikolka volcanoes, as well as Tolbachik and Ploskie Sopki regional zones of cinder cones. The volcanic rocks of the first association differ from those of the second one in higher magnesium contents; elevated Sr; lower Ca, Sc, Y, and Yb; higher Sr/Y, K/Ti, La/Yb, Zr/Y, Th/Yb, Ni/Sc, Cr/Sc and lower Ca/Sr and U/Th ratios. Variations of Sr and Nd isotopic ratios in volcanics of these associations overlap. The covariations between Sr and Nd isotope characteristics and isotopic ratios with some major- and trace-element contents differ in these two associations. We concluded that the parental melts for the rocks of these associations were formed during the metasomatic transformation of mantle wedge under the influence of two different agents: partial melts generated within the subducted slab, for the northern volcanoes; and fluids derived from the subducted slab, for the southern ones. This discrepancy is probably related to different subduction conditions: oblique, gently dipping, slow subduction (like in the western Aleutians) beneath the northern volcanoes; and orthogonal subduction of ancient oceanic crust beneath the southern ones.
The eruptive history of the Shiveluch andesite volcano included two Holocene events, during which the volcano erupted unusual rocks: medium-potassium, amphibole-bearing magnesian basalts (7600 years ago) and high-potassium magnesian basalts with phlogopite and amphibole (3600 years ago). The volumes of tephra were approximately 0.1 and 0.3 km3, respectively. Some of the mineralogical and geochemical features of the Holocene basalts were inherited by the subsequent basaltic andesites and andesites. These are similar in Mg variation ranges of olivine, clinopyroxene, and amphibole phenocrysts, high Mg contents, and high Cr and Ni concentrations. This and the results of mass-balance calculations do not contradict the view that the Shiveluch volcanic rocks originated during the crystal fractionation of Holocene basalt melts. However, the other geochemical features of the Shiveluch rocks, e.g., their similar REE contents, cast doubt on the formation of the magnesian basaltic andesites through fractional crystallization of magnesian basalt magma and suggest that they originated as a result of interaction between magnesian basalt magma and a depleted mantle material at a shallow depth. At the same time, the different mineral compositions of the Holocene medium- and high-potassium basalts and the results of mass-balance calculations indicate that their parental magmas might be produced by the melting of different rocks. Copyright © 1997 by MAEe cyrillic signK Hayκa/Interperiodica Publishing.
Most of the Kharchinskii and Zarechnyi products, as well as those of the Kharchinskii cinder cones, are magnesian rocks. Mineralogical data suggest that both the basaltic and the andesitic magma were rich in water (≥3-4 and >6-7 wt.%, respectively) and crystallized at high oxygen fugacity (2.0-2.5 orders of magnitude higher than the NNO buffer). These features, coupled with the geochemical characteristics of these basalts and andesites, indicate that they are similar to the rocks of Shiveluch, a volcano also located on the northern flank of the Northern volcanic group, but differ from the rocks of the other volcanoes of this group which are located further south. The Kharchinskii, Zarechnyi, and Shiveluch magnesian basalts differ from the rocks of the Klyuchevskoi volcano and Tolbachik lava field by their higher K, Ba, Sr and lower Ca, Sc, Yb contents at higher La/Yb, Ni/Sc, and La/Ta ratios, while their initial magmas were more hydrous and more oxidized.
A tephrochronological study and radiocarbon dating of soil-pyroclastic sequences were carried out along a profile of Shiveluch Volcano-Chernyi Yar-Bering Islands. Ashes deposited by the largest Shiveluch eruptions (for the last 6500 years) were discovered and identified in the southeastern sector of ash dispersal. Ashes of the Bezymyannyi, Ksudach, Klyuchevskoi, and Khangar volcanoes were identified. The detailed dating of the Chernyi Yar peat bog helped to improve the timing of the eruptions and estimate the ash fall frequency for the area of the lower reaches of the Kamchatka River: one ash fall per 191 years. In addition to the 1964 Shiveluch Tephra, the following ash layers are proposed to be used as regional geochronological markers (ages in years are given in the parentheses): SH1 (265), SH2 (295), SP (1450, 2800, and 3600), and SHdv (4105) of SHiveluch, and also KS1 (1806) of Ksudach and AV2 (5489) of Avacha Volcano.
The Kamchatka arc (Russia) is located in the northwestern Pacific Ocean and is divided into three segments by major sub-latitudinal fault zones (crustal discontinuities). The southern (SS) and central (CS) segments are associated with the subduction of old Pacific lithosphere, whereas the northern, inactive segment (NS) was formed during westward subduction of young (< 15 Ma) Komandorsky Basin oceanic crust. Further segmentation of the arc is outlined by the development of the Central Kamchatka Depression (CKD) intra-arc rift, which is oriented parallel to the arc and is splitting the CS into the active Eastern Volcanic Front (EVF) and the largely inactive, rear-arc Sredinny Range. The NS volcanics (15-5 Ma) include calc-alkaline lavas, shoshonites, adakites, and Nb-enriched arc basalts. Isotopically all magma types share high 143Nd/144Nd ratios of 0.512976-0.513173 coupled with variable 87Sr/86Sr (0.702610-0.70356). NS lavas plot within or slightly above the Pacific MORB field on the Pb isotopic diagrams. The EVF volcanoes have more radiogenic 143Nd/144Nd (0.51282-0.513139) and 208Pb/204Pb (38.011–38.1310) than the NS lavas. CKD lavas display MORB-like Nd isotope ratios at slightly elevated 87Sr/86Sr values accompanied by a slightly less radiogenic Pb composition. Kamchatka lavas are thought to be derived from a MORB-like depleted source modified by slab-derived siliceous melts (adakites) and fluids (NS), or fluids alone (CS and SS). The NS and EVF lavas may have been contaminated by small fractions of a sedimentary component that isotopically resembles North Pacific sediment. Petrogenesis in the Kamchatka arc is best explained by a three-component model with depleted mantle wedge component modified by two slab components. Slab-derived hydrous melts produced incompatible element characteristics associated with northern segment lavas, while hydrous slab fluids caused melting in the depleted mantle below the southern and central segments of the Kamchatka arc. Trace element characteristics of Kamchatka lavas appear to be controlled by slab fluids or melts, while radiogenic isotope ratios which are uniform throughout the arc reflect depleted composition of sub-arc mantle wedge.
Rocks with the geochemical characteristics of melts derived directly from subducted lithosphere are present in some modern island and continental arcs where relatively young and hot lithosphere is being subducted. These andesites, dacites, and sodic rhyolites or their intrusive equivalents are usually not associated with parental basaltic magmas. It is shown here that the trace-element geochemistry of these magmas is consistent with a derivation by partial melting of the subducted slab, and in particular that subducting lithosphere younger than 25 Myr seems to be required for slab melting to occur.
The Kurile-Kamchatka Late Cenozoic volcanic rocks can be categorized as magmatic series of island arc and within-plate geochemical types, respectively. These types clearly can be identified on geochemical discriminant diagrams. Across-arc geochemical, mineralogical, and Sr-Nd-isotope zoning is characteristic of island-arc volcanics, but is not found for within-plate volcanics. Such zoning probably is the result of modification of fluid-phase composition, which originates in the underlying subducting plate (as a result of dehydration of water-bearing secondary minerals) and rises into the zone of island-arc magma generation in the mantle wedge. Along-arc Sr, Be, H., and 0 isotopic zoning is noted for island-arc volcanics. Probably it is associated with various levels of island-arc magma contamination. 10Be data for modern island-arc lavas attest to the fact that young pelagic sediments from the subducting plate participate in island-arc magma genesis.Within-plate lavas are found in the region north of Avacha Bay. They may precede island-arc volcanics (East Kamchatka), coexist with them during the late stage of volcanic activity (Central Range), or be completely unrelated to island-arc volcanics in the far rear arc (West Kamchatka). The appearance of within-plate lavas probably is connected with deep faults that accompanied the formation of the northern Kurile-Kamchatka trench and the associated new subduction zone in this part of the island-arc system, an event caused by the accretion of the Kronotskiy terrane to eastern Kamchatka in Middle Miocene time.
The Bering Sea coast of Kamchatka overlies a boundary between the proposed Okhotsk and Bering blocks, or (micro)plates, of the North American plate in the Russian Far East. A history of tsunamis along this coast for the past 4000 yr indicates that the zone north of the Kuril-Kamchatka subduction zone produces tsunamigenic earthquakes every few centuries. Such a record is consistent with convergence of the proposed Okhotsk and Bering blocks along the Bering Sea coast of Kamchatka. A tsunami deposit from the 1969 Mw 7.7 Ozernoi earthquake helps us interpret older tsunami deposits. Newly studied tephra layers from Shiveluch volcano as well as previously established marker tephra layers in northern Kamchatka provide age control for historic and prehistoric tsunami deposits. Based on >50 measured sections along 14 shoreline profiles, tsunami-deposit frequencies in the southwestern Bering Sea are about five per thousand years for tsunamis generated north of the Kuril-Kamchatka trench.
Restudy of deposits at Shiveluch in comparison with other data has shown that the sequence of eruptive events at Shiveluch volcano on 12 November 1964 was the following: edifice failure involving 1.154 km3 of material at 07:07 a.m.; phreatic explosion with ejection of resurgent ash with a volume of 0.01 km3; Plinian activity between 07:20 and 07:47 a.m., during which andesitic juvenile tephra with a volume of 0.3 km3 erupted. During the final stage of the eruption between 07:47 and 08:22 a.m., pyroclastic flows with a volume of 0.3 – 0.5 km3 were erupted. In this sequence, there was no catastrophic directed blast with generation of a destructive pyroclastic density current like those that took place at Bezymianny volcano in 1956 and at Mount St. Helens in 1980. The absence of a directed blast is attributed to the fact that the 1964 eruption occurred before magma had enough time to intrude into the edifice and build a cryptodome. The failure of the edifice depressurized only a hydrothermal system that existed around the old domes. This appears to have been insufficient for the generation of a catastrophic directed blast.The case history of volcanic activity at Shiveluch before 1964 suggests that if the edifice of the Young Shiveluch had been stronger and had not failed by landsliding, the eruption of 1964 might have consisted of prolonged dome extrusion with relatively weak explosive activity.
We studied the tectonic setting, morphology, geologic structure, history of eruptive activity and evolution of the composition of the erupted material of Kizimen volcano, Kamchatka, from the moment of its origination 11–12 thousand years ago to the present time. Four cycles, each 2–3.5 thousand years long, were distinguished that characterize the activity of the volcano. All of the largest eruptions were dated, and their parameters determined. We also estimated the volume and the mass of the erupted products, the volcanic intensity of eruption of material during periods of high activity, and the amount of material the volcano ejected at different stages of its formation. It has been shown that the evolution of the composition of the rocks erupted (from dacite to basaltic andesite) takes place as a result of mixing of dacitic and basaltic magma. It is suggested that future eruptions that may take place at Kizimen may be similar to those at Bandai (1888) and Mount St. Helens (1980) volcanoes.
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 km 3) to catastrophic (up to 20–30 km 3), 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 km 3 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 km 3) and active Kambalny (5–10 km 3) 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 km 3 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.
On November 12, 1964, after a long swarm of preliminary earthquakes a gigantic directed blast took place at Shiveluch Volcano.
The Crater top of the volcano with five large domes was completely destroyed. The deposits of the directed blast fell on an
area of 98 sq. km, at a distance up to 10 km from the crater. The volume of the deposits is 1.5 km3 at least.
A new crater was formed, its size is 1.5 × 3 km. Numerous pyroclastic flows were poured out the new crater.
The eruption lasted only one hour, its thermal energy is 1,3 × 1025 ergs, kinetic energy of the blast − 1 × 1024 ergs, air wave energy − 1,8 × 1021 ergs. Initial velocity of the explosion: 280–310m/sec, pressure: 800–1000atm.
The eruption of Shiveluch volcano belongs to the « Bezymianny type » eruption.
Shiveluch Volcano, located in the Central Kamchatka Depression, has experienced multiple flank failures during its lifetime,
most recently in 1964. The overlapping deposits of at least 13 large Holocene debris avalanches cover an area of approximately
200 km2 of the southern sector of the volcano. Deposits of two debris avalanches associated with flank extrusive domes are, in addition,
located on its western slope. The maximum travel distance of individual Holocene avalanches exceeds 20 km, and their volumes
reach ∼3 km3. The deposits of most avalanches typically have a hummocky surface, are poorly sorted and graded, and contain angular heterogeneous
rock fragments of various sizes surrounded by coarse to fine matrix. The deposits differ in color, indicating different sources
on the edifice. Tephrochronological and radiocarbon dating of the avalanches shows that the first large Holocene avalanches
were emplaced approximately 4530–4350 BC. From ∼2490 BC at least 13 avalanches occurred after intervals of 30–900 years. Six
large avalanches were emplaced between 120 and 970 AD, with recurrence intervals of 30–340 years. All the debris avalanches
were followed by eruptions that produced various types of pyroclastic deposits. Features of some surge deposits suggest that
they might have originated as a result of directed blasts triggered by rockslides. Most avalanche deposits are composed of
fresh andesitic rocks of extrusive domes, so the avalanches might have resulted from the high magma supply rate and the repetitive
formation of the domes. No trace of the 1854 summit failure mentioned in historical records has been found beyond 8 km from
the crater; perhaps witnesses exaggerated or misinterpreted the events.
In this paper we evaluate the results of radiocarbon dating in regions of young volcanism in Kamchatka and assess their applicability to the development of the history of Holocene regional volcanic activity.Dates were obtained mainly on buried soils, the most widespread and commonly dated material in Kamchatka. The main criteria used to assess the validity of radiocarbon ages are: (1) there should be a normal upward sequence of progressively younger dates in a soil-pyroclastic section; (2) absence of significant age deviation in replicate soil samples from the same stratigraphic interval; and (3) concordance of ages obtained on different materials — buried soils, peat, wood and charcoal — at the same stratigraphic level.Results indicate that there are no significant deviations in radiocarbon ages due to the effects of volcanic activity with the exception of dates determined on charcoal from pyroclastic flows and surges. The radiocarbon ages of tephra marker beds are closely reproduced in sections separated from each other by tens to hundreds of kilometers. We conclude that radiocarbon dating makes it possible to establish a reliable time-framework of large volcanic eruptions in Kamchatka during the Holocene.
The deep structure, Wadati-Benioff zone (focal zone) geometry and the magma feeding system of Shiveluch volcano are investigated based on 1962–1994 detailed seismic surveillance.A focal zone beneath Shiveluch is dipping at an angle of 70° at depths of 100–200 km. Based on the revealed interrelations between seismicity at depths of 105–120 km and an extrusive phase of its eruptions in 1980 through 1994, it is inferred that primary magmas, periodically feeding the crustal chamber, are melted at depths of at least 100 km. An upsurge of extrusive-explosive activity at the volcano is preceded and accompanied by the increasing number and energy of both volcanic earthquakes beneath the dome and tectonic or volcano-tectonic earthquakes in the zones of NW-striking crustal faults near the volcano.The eruption of April 1993 has been the most powerful since 1964. It was successfully predicted based on interactive use of all seismic data. At the same time the influence of seismicity at depths of 105–120 km under the volcano on the style (and consequently on prediction) of its activity is decisive.
Detailed tephrochronological studies in Kamchatka Peninsula, Russia, permitted documentation of 24 Holocene key-marker tephra layers related to the largest explosive eruptions from 11 volcanic centers. Each layer was traced for tens to hundreds of kilometers away from the source volcano; its stratigraphic position, area of dispersal, age, characteristic features of grain-size distribution, and chemical and mineral composition confirmed its identification. The most important marker tephra horizons covering a large part of the peninsula are (from north to south; ages given in14C yr B.P.) SH2(≈1000 yr B.P.) and SH3(≈1400 yr B.P.) from Shiveluch volcano; KZ (≈7500 yr B.P.) from Kizimen volcano; KRM (≈7900 yr B.P.) from Karymsky caldera; KHG (≈7000 yr B.P.) from Khangar volcano; AV1(≈3500 yr B.P.), AV2(≈4000 yr B.P.), AV4(≈5500 yr B.P.), and AV5(≈5600 yr B.P.) from Avachinsky volcano; OP (≈1500 yr B.P.) from the Baraniy Amfiteatr crater at Opala volcano; KHD (≈2800 yr B.P.) from the “maar” at Khodutka volcano; KS1(≈1800 yr B.P.) and KS2(≈6000 yr B.P.) from the Ksudach calderas; KSht3(A.D. 1907) from Shtyubel cone in Ksudach volcanic massif; and KO (≈7700 yr B.P.) from the Kuril Lake-Iliinsky caldera. Tephra layers SH5(≈2600 yr B.P.) from Shiveluch volcano, AV3(≈4500 yr B.P.) from Avachinsky volcano, OPtr(≈4600 yr B.P.) from Opala volcano, KS3(≈6100 yr B.P.) and KS4(≈8800 yr B.P.) from Ksudach calderas, KSht1(≈1100 yr B.P.) from Shtyubel cone, and ZLT (≈4600 yr B.P.) from Iliinsky volcano cover smaller areas and have local stratigraphic value, as do the ash layers from the historically recorded eruptions of Shiveluch (SH1964) and Bezymianny (B1956) volcanoes. The dated tephra layers provide a record of the most voluminous explosive events in Kamchatka during the Holocene and form a tephrochronological timescale for dating and correlating various deposits.
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