Churikova Tatiana G., Gordeychik Boris N., Iwamori Hikaru, Nakamura Hitomi, Ishizuka Osamu, Nishizawa Tatsuji, Haraguchi Satoru, Miyazaki Takashi, Vaglarov Bogdan S. Petrological and geochemical evolution of the Tolbachik volcanic massif, Kamchatka, Russia // Journal of Volcanology and Geothermal Research. 2015. Vol. 307. P. 156 - 181. doi: 10.1016/j.jvolgeores.2015.10.026.
Data on the geology, petrography, and geochemistry of Middle–Late-Pleistocene rocks from the Tolbachik volcanic massif (Kamchatka, Klyuchevskaya group of volcanoes) are presented and compared with rocks from the neighboring Mount Povorotnaya, Klyuchevskaya group basement, and Holocene–historical Tolbachik monogenetic cones. Two volcanic series of lavas, middle-K and high-K, are found in the Tolbachik massif. The results of our data analysis and computer modeling of crystallization at different P–T–H2O–fO2 conditions allow us to reconstruct the geochemical history of the massif. The Tolbachik volcanic massif started to form earlier than 86 ka based on K–Ar dating. During the formation of the pedestal and the lower parts of the stratovolcanoes, the middle-K melts, depleted relative to NMORB, fractionated in water-rich conditions (about 3 of H2O). At the Late Pleistocene–Holocene boundary, a large fissure zone was initiated and the geodynamical regime changed. Upwelling associated with intra-arc rifting generated melting from the same mantle source that produced magmas more enriched in incompatible trace elements and subduction components; these magmas are high-K, not depleted relative to N-MORB melts with island arc signatures and rift-like characteristics. The fissure opening caused degassing during magma ascent, and the high-K melts fractionated at anhydrous conditions. These high-K rocks contributed to the formation of the upper parts of stratovolcanoes. At the beginning of Holocene, the high-K rocks became prevalent and formed cinder cones and associated lava fields along the fissure zone. However, some features, including 1975–1976 Northern Breakthrough, are represented by middle-K high-Mg rocks, suggesting that both middle-K and high-K melts still exist in the Tolbachik system. Our results show that fractional crystallization at different water conditions and a variably depleted upper mantle source are responsible for all observed variations in rocks within the Tolbachik volcanic massif. Sr–Nd isotopes are consistent with 2–4 crustal assimilation during formation of the pedestal and stratovolcanoes, while the young lava fields do not show evidence of crustal assimilation. Major and trace element data coupled with K–Ar dating provide strong evidence that Mount Povorotnaya, located in 8 km northeast of Plosky Tolbachik, is an old block of the Tolbachik massif pedestal and for the moment it is the oldest (306 ka) known object in Klyuchevskaya group of volcanoes.
Churikova Tatiana, Gordeychik Boris, Wörner Gerhard, Flerov Gleb, Hartmann Gerald, Simon Klaus Geochemical evolution of Bolshaya Udina, Malaya Udina, and Gorny Zub volcanoes, Klyuchevskaya Group (Kamchatka) // Geophysical Research Abstracts. 2017. Vol. 19. P. EGU2017-10691.
The Klyuchevskaya group of volcanoes (KGV) located in the northern part of Kamchatka has the highest magma production rate for any arc worldwide and several of its volcanoes have been studied in considerable detail [e.g. Kersting & Arculus, 1995; Pineau et al., 1999; Dorendorf et al., 2000; Ozerov, 2000; Churikova et al., 2001, 2012, 2015; Mironov et al., 2001; Portnyagin et al., 2007, 2015; Turner et al., 2007]. However, some volcanoes of the KGV including Late-Pleistocene volcanoes Bolshaya Udina, Malaya Udina, Ostraya Zimina, Ovalnaya Zimina, and Gorny Zub were studied only on a reconnaissance basis [Timerbaeva, 1967; Ermakov, 1977] and the modern geochemical studies have not been carried out at all. Among the volcanoes of KGV these volcanoes are closest to the arc trench and may hold information on geochemical zonation with respect to across arc source variations. We present the first major and trace element data on rocks from these volcanoes as well as on their basement. All rocks are medium-calc-alkaline basaltic andesites to dacites except few low-Mg basalts from Malaya Udina volcano. Phenocrysts are mainly olivine, pyroxene, plagioclase and magnetite, Hb-bearing andesites and dacites are rarely found only in subvolcanic intrusions at Bolshaya Udina volcano. Lavas are geochemically similar to the active Bezymianny volcano, however, individual variations for each volcano exist in both major and trace elements. Trace element geochemistry is typical of island arc volcanism. Compared to KGV lavas all studied rocks form very narrow trends in all major element diagrams, which almost do not overlap with the fields of other KGV volcanoes. The lavas are relatively poor in alkalis, TiO2, P2O5, FeO, Ni, Zr, and enriched in SiO2 compared to other KGV volcanics and show greater geochemical and petrological evidence of magmatic differentiation during shallow crustal processing. Basement samples of the Udinskoe plateau lavas to the east of Bolshaya Udina volcano have similar geochemical composition (trace element enriched high-K basaltic andesites and andesites) and similar eruption age of 274 ka [Calkins et al., 2004] as typical plateau lavas below the northern KGV. This research was supported by RFBR-DFG grant # 16-55-12040.
Churikova Tatiana, Wörner Gerhard, Mironov Nikita, Kronz Andreas Volatile (S, Cl and F) and fluid mobile trace element compositions in melt inclusions: implications for variable fluid sources across the Kamchatka arc // Contributions to Mineralogy and Petrology. 2007. Vol. 154. № 2. P. 217-239. doi:10.1007/s00410-007-0190-z.
Volatile element, major and trace element compositions were measured in glass inclusions in olivine from samples across the Kamchatka arc. Glasses were analyzed in reheated melt inclusions by electron microprobe for major elements, S and Cl, trace elements and F were determined by SIMS. Volatile element–trace element ratios correlated with ﬂuid-mobile elements (B, Li) suggesting successive changes and three distinct ﬂuid compositions with increasing slab depth. The Eastern Volcanic arc Front (EVF) was dominated by ﬂuid highly enriched in B, Cl and chalcophile elements and also LILE (U, Th, Ba, Pb), F, S and LREE (La, Ce). This arc-front ﬂuid contributed less to magmas from the central volcanic zone and was not involved in back arc magmatism. The Central Kamchatka Depression (CKD) was dominated by a second ﬂuid enriched in S and U, showing the highest S/K2O and U/Th ratios. Additionally this ﬂuid was unusually enriched in 87Sr and 18O. In the back arc Sredinny Ridge (SR) a third ﬂuid was observed, highly enriched in F, Li, and Be as well as LILE and LREE. We argue from the decoupling of B and Li that dehydration of different water-rich minerals at different depths explains the presence of different ﬂuids across the Kamchatka arc. In the arc front, ﬂuids were derived from amphibole and serpentine dehydration and probably were water-rich, low in silica and high in B, LILE, sulfur and chlorine. Large amounts of water produced high degrees of melting below the EVF and CKD. Fluids below the CKD were released at a depth between 100 and 200 km due to dehydration of lawsonite and phengite and probably were poorer in water and richer in silica. Fluids released at high pressure conditions below the back arc (SR) probably were much denser and dissolved signiﬁcant amounts of silicate minerals, and potentially carried high amounts of LILE and HFSE.
Dirksen O., Humphreys M.C.S., Pletchov P., Melnik O., Demyanchuk Y., Sparks R.S.J., Mahony S. The 2001–2004 dome-forming eruption of Shiveluch volcano, Kamchatka: Observation, petrological investigation and numerical modelling // Journal of Volcanology and Geothermal Research. 2006. Vol. 155. № 3–4. P. 201 - 226. doi: 10.1016/j.jvolgeores.2006.03.029.
There have been three episodes of lava dome growth at Shiveluch volcano, Kamchatka since the Plinian explosive eruption in 1964. The episodes in 1980–1981, 1993–1995 and 2001–2004 have discharged at least 0.27 km3 of silicic andesite magma. A time-averaged mean extrusion rate of 0.2 m3/s is thus estimated for the last 40 years. Here the 2001–2004 activity is described and compared with the earlier episodes. The recent activity involved three pulses in extrusion rate and a transition to ongoing lava extrusion. Estimated magma temperatures are in the range 830 to 900 °C, with 850 °C as the best estimate, using the plagioclase−amphibole phenocryst assemblage and Fe−Ti oxides. Melt inclusions in amphibole and plagioclase have maximum water contents of 5.1 wt.%, implying a minimum pressure of ∼ 155 MPa for water-saturated conditions. The magma chamber depth is estimated to be about 5–6 km or more, a result consistent with geophysical data. The thicknesses of opx–mt–amph reaction rims on olivine xenocrysts are used to estimate the residence time of olivine crystals in the shallow chamber in the range 2 months to 4 years, suggesting replenishment of deeper magma into the shallow chamber contemporaneous with eruption. The absence of decompression-driven breakdown rims around amphiboles indicates ascent times of less than 7 days. Volcanological observations of the start of the 2001–2004 episode suggest approximately 16 days for the ascent time and a conduit equivalent to a cylinder of diameter approximately 53–71 m. Application of a conduit flow model indicates that the magma chamber was replenished during the 2001–2004 eruption, consistent with the results of olivine reaction rims, and that the chamber has an estimated volume of order 7 km3.
Dirksen O., van den Bogaard C., Danhara T., Diekmann B. Tephrochronological investigation at Dvuh-yurtochnoe lake area, Kamchatka: Numerous landslides and lake tsunami, and their environmental impacts // Quaternary International. 2011. Vol. 246. № 1-2. P. 298 - 311. doi: 10.1016/j.quaint.2011.08.032.
Distal volcanic tephras in soil sections and lake sediments in the Dvuh-yurtochnoe (Two-Yurts) lake area, central Kamchatka, were investigated in order to provide a chronological framework for the reconstruction of late Quaternary landscape development. Mineralogical and geochemical data point to sources from 5 volcanoes. Ten tephra layers were identified and correlated to known eruptive events. The ages were corroborated by radiocarbon dating of the soil sections around Two-Yurts lake. These findings allow the reconstruction of regional paleoenvironmental change, recorded in the soil sections around Two-Yurts lake. During the Last Glacial Maximum (LGM) time, the area was affected by glacial advances that produced the glacial moraines at the eastern outlet of the lake. A large landslide, ca. 15,000–18,000 14C BP, dammed the valley and led to formation of Two-Yurts lake. Several more landslide events can be recognized in the Holocene, and one affected Two-Yurts lake ca. 3000 14C BP. This event produced a “tsunami”, documented by poorly sorted deposits with rounded pebbles in the onshore sections around the lake. In contrast to the soil sections, tephras buried in the “soupy” lacustrine sediments of Two-Yurts lake are not well preserved and show inconsistent age-depth relationships compared to those suggested by radiocarbon dating, due to sinking through the lake sediments. Nevertheless, tephrochronological data revealed the strong impact of terrestrial landslides on lake sedimentation.
Dirksen O.V., Bazanova L.I. An eruption of the Veer cone as a volcanic event during the increase of volcanic activity in Kamchatka at the beginning of the Christian Era // Journal of Volcanology and Seismology. 2010. Vol. 4. № 6. P. 378-384. doi: 10.1134/S0742046310060023.
Tephrochronologic studies conducted in the Levaya Avacha River valley helped determine the true age of the Veer cinder cone, which formed approximately in 470 AD (1600 14C BP). These data refute the existing idea that it was generated in 1856. The monogenetic Veer cone should be cancelled from the catalogs of historical eruptions and active volcanoes in Kamchatka. The eruption of this cone was a reflection of the all-Kamchatkan increase in the activity of endogenous processes that occurred in 0–650 AD.
Тефрохронологические исследования, проведенные в долине р. Левая Авача, позволили установить истинный возраст шлакового конуса Веер, который образовался примерно в 470 г. н.э. (1600 14 л.н.). Эти данные опровергают существовавшие до настоящего времени представления о дате его формирования в 1856 г. Моногенный конус Веер необходимо исключить из каталогов исторических извержений и действующих вулканов Камчатки. Извержение конуса явилось проявлением общекамчатской активизации эндогенных процессов, происходившей в 0-650 гг. н.э.
Dirksen O.V., Bazanova L.I., Pletchov P.Yu., Portnyagin M.V., Bychkov K.A. Volcanic activity at Sedankinsky Dol lava field, Sredinny Ridge, during the Holocene (Kamchatka, Russia) // Abstracts. 4rd Biennial Workshop on Subduction Processes emphasizing the Kurile-Kamchatka-Aleutian Arcs (JKASP-4). Linkages among tectonics, seismicity, magma genesis, and eruption in volcanic arcs. August 21-27, 2004. Petropavlovsk-Kamchatsky: Institute of Volcanology and Seismology FEB RAS. 2004. P. 55
Dirksen O.V., Melekestsev I.V. Chronology, evolution and morphology of plateau basalt eruptive centers in Avacha River Area, Kamchatka, Russia // Volcanology and Seismology. 1999. Vol. 21. № 1. P. 1-27.
Nineteen Holocene eruptive centers (cinder cones with lava flows and maars) were located and described in the Avacha horst and anticline zone west of the East Kamchatka volcanic area. A tephrochronological study and the carbon-14 dating of soil and plant remains ranked the eruptive centers into three age groups: 11 000-7700, 3000-2500, and 1200-600 carbon-14 years B. P. The eruptive centers of these groups are believed to have been operating roughly synchronously with the periods of active magma injection in the East Kamchatka volcanic area. Eruptive histories were reconstructed for some of the volcanic centers. The structural and tectonic settings, geographical positions, and elevations of the centers were analyzed. The volume (1.1 km3) and weight (1.8 X 10^9 metric tons) of the erupted rocks were evaluated. The productivity of the plateau basalt volcanism was found to be 10-100 times lower than the plateau basalt productivity in the area of grabens and synclines, possibly, because of the more shallow basement in the horsts and because of the fact that the compression of the crust under uplifting conditions hampered the magma rise toward the surface. Most of the lavas and pyroclastics are basalts of the medium-potassic series, some having medium (54-62) and some elevated (65-70) Kmg values.
Donnadieu Franck, Merle Olivier, Besson Jean-Claude Volcanic edifice stability during cryptodome intrusion // Bulletin of Volcanology. 2001. Т. 63. № 1. С. 61-72. doi:10.1007/s004450000122.
Limit equilibrium analyses were applied to the 1980 Mount St. Helens and 1956 Bezymianny failures in order to examine the influence on stability of structural deformation produced by cryptodome emplacement. Weakening structures associated with the cryptodome include outward-dipping normal faults bounding a summit graben and a flat shear zone at the base of the bulged flank generated by lateral push of the magma. Together with the head of the magmatic body itself, these structures serve directly to localize failure along a critical surface with low stability deep within the interior of the edifice. This critical surface, with the safety coefficient reduced by 25–30%, is then very sensitive to stability condition variation, in particular to the pore-pressure ratio (ru) and seismicity coefficient (n). For ru=0.3, or n=0.2, the deep surface suffers catastrophic failure, removing a large volume of the edifice flank. In the case of Mount St. Helens, failure occurred within a material with angle of friction ~40°, cohesion in the range 105–106 Pa, and probably significant water pore pressure. On 18 May 1980, detachment of slide block I occurred along a newly formed rupture surface passing through the crest of the bulge. Although sliding of block I may have been helped by the basal shear zone, significant pore pressure and a triggering earthquake were required (ru=0.3 and n=0.2). Detachment of the second block was guided by the summit normal fault, the front of the cryptodome, and the basal shear zone. This occurred along a deep critical surface, which was on the verge of failure even before the 18 May 1980 earthquake. The stability of equivalent surfaces at Bezymianny Volcano appears significantly higher. Thus, although magma had already reached the surface, weaker materials, or higher pore pressure and/or seismic conditions were probably required to reach the rupture threshold. From our analysis, we find that deep-seated sector collapses formed by removing the edifice summit cannot generally result from a single slide. Cryptodome-induced deformation does, however, provide a deep potential slip surface. As previously thought, it may assist deep-seated sector collapse because it favors multiple retrogressive slides. This leads to explosive depressurization of the magmatic and hydrothermal systems, which undermines the edifice summit and produces secondary collapses and explosive blasts.
Dorendorf F., Churikova T., Koloskov A., Wörner G. Late Pleistocene to Holocene activity at Bakening volcano and surrounding monogenetic centers (Kamchatka): volcanic geology and geochemical evolution // Journal of Volcanology and Geothermal Research. 2000. Vol. 104. № 1–4. P. 131 - 151. doi: 10.1016/S0377-0273(00)00203-1.
The different roles of variable mantle sources and intra-crustal differentiation processes at Bakening volcano (Kamchatka) and contemporaneous basaltic monogenetic centers are studied using major and trace elements and isotopic data.
Three suites of volcanic activity are recognized: (1) plateau basalts of Lower Pleistocene age; (2) andesites and dacites of the Bakening volcano, the New Bakening volcano dacitic centers nearby; and (3) contemporaneous basaltic cinder cones erupted along subduction zone—parallel N–S faults. Age-data show that the last eruptions in the Bakening area occurred only 600–1200 years ago, suggesting the volcano is potentially active.
Major element variations and petrographic observations provides evidence for a fractionation assemblage of olivine, clinopyroxene, ±plagioclase, ±magnetite (?) within the basaltic suite. The fractionation in the andesites and dacites is dominated by amphibole, clinopyroxene, orthopyroxene and plagioclase plus minor amounts of magnetite and apatite. The youngest cpx-opx-andesites of Bakening main volcano deviate from that trend. Their source was probably formed by mixing of basaltic magmas into the silicic magma chamber of the Bakening volcano. Overall trace element patterns as well as the Sr–Nd–Pb isotopic compositions are quite similar in all rocks despite large differences in their chemical composition (from basalt to rhyodacite). In detail however, the andesite–dacites of the central Bakening volcano show a stronger enrichment in the more incompatible elements and depletion in HREE compared to the monogenetic basaltic centers. This results in a crossing of the REE-pattern for the two suites. The decrease in the HREEs can be explained by amphibole fractionation. A slab component is less likely because it would result in fractionation of the HREE from each other, which is not observed. The higher relative amounts of LILE in the dacitic and the large scatter in the basaltic rocks must be the result of a variable source enrichment by slab-derived fluids overprinting a variable depleted mantle wedge. The plateau basalts are less depleted in HFSE and show a more fractionated HREE pattern. These lavas could either result from a slab component or the addition of an OIB-type enriched mantle in their source.