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 G
Geochronology of the greatest Holocene explosive eruptions in Kamchatka and their imprint on the Greenland glacier shield (1997)
Braitseva O.A., Sulerzhitskii L.D., Ponomareva V.V., Melekestsev I.V. Geochronology of the greatest Holocene explosive eruptions in Kamchatka and their imprint on the Greenland glacier shield // Transactions (Doklady) of the Russian Academy of Sciences. Earth science section. 1997. V. 352. № 1. P. 138-140.
http://repo.kscnet.ru/907/ [связанный ресурс]
Geologic and petrologic study of the Central Kurile Islands, VI - Dzigoku Volcano, Urup Island (1937)
Nemoto T. Geologic and petrologic study of the Central Kurile Islands, VI - Dzigoku Volcano, Urup Island // Bulletin of the Volcanological Society of Japan. 1937. V. 3. № 2.
Geological Effect of 2005 Eruptions of Sheveluch Volcano, Kamchatka, Russia (2006)
Girina O.A., Gorbach N.V., Nuzhdaev A.A. Geological Effect of 2005 Eruptions of Sheveluch Volcano, Kamchatka, Russia // Abstracts. 5rd Biennial Workshop on Subduction Processes emphasizing the Japan-Kurile-Kamchatka-Aleutian Arcs (JKASP-5). 2006. P. 43
Geology, petrology and geochemistry of the Tolbachik volcanic massif, Kamchatka, Russia (2015)
Churikova T., Gordeychik B., Iwamori H., Nakamura H., Ishizuka O., Nishizawa T., Haraguchi S., Yasukawa K., Miyazaki T., Vaglarov B., Ueki K., Toyama C., Chang Q., Kimura J.I. Geology, petrology and geochemistry of the Tolbachik volcanic massif, Kamchatka, Russia // 26th IUGG General Assembly 2015. June 22 - July 2, 2015, Prague, Czech Republic. 2015. P. VS28p-487.    Аннотация
Data on the geology, petrography, and geochemistry of previously geochemically unstudied Middle-Late-Pleistocene rocks from Tolbachik volcanic massif (Central Kamchatka Depression, CKD) are presented. Two volcanic series – middle-K and high-K were erupted. The geochemical history of the massif was started earlier 86 ka (K-Ar dating) with the formation of the Tolbachik pedestal presented by middle-K series. During stratovolcanoes formation both series occur and the role of high-K melts was increasing with time. In Holocene high-K rocks are dominated but some cinder cone lavas are presented by middle-K high-Mg melts which suggest that both volcanic series are still exists. The computer modeling show that both series can be explained by the process of crystal fractionation at different water content from nearly or the same mantle source similar to high-Mg basalts of 1975 Northern Breakthrough. Middle-K rocks could crystallize at water-rich conditions (more than 2% of H2O) while the high-K rock could crystallize at dry conditions at the same pressure. However the existence of different mantle sources and possible magma mixing cannot be excluded. Our data show that fractional crystallization at different P-T-H2O-fO2 conditions can be one of the main processes responsible for rock variations at CKD. Sr-Nd-Pb isotopes suggest 2-4% of crustal assimilation to the magma chamber during pedestal and stratovolcanoes formation while lava-cinder cones are not show evidences of crustal assimilation. Major and trace element data coupled with K-Ar dating provide strong evidence that Povorotnaya mount located in 8 km NE of Plosky Tolbachik is the old block of the Tolbachik massif pedestal and for the moment the oldest known object (306 ka by K-Ar dating) in Klyuchevskaya group.

Geology, petrology and geochemistry of the Tolbachik volcanic massif, Kamchatka, Russia. Available from: https://www.researchgate.net/publication/282656425_Geology_petrology_and_geochemistry_of_the_Tolbachik_volcanic_massif_Kamchatka_Russia [accessed Jun 19, 2017].
Geomagnetic and Bathymetric Study of the Okhotsk Sea - (1) (1967)
Yasui M., Hashimoto Y., Ueda S. Geomagnetic and Bathymetric Study of the Okhotsk Sea - (1) // Oceanographical Magazine. 1967. V. 19. № 1. P. 73-85.
Gigantic Eruption of the Volcano Bezymianny (1959)
Gorshkov G.S. Gigantic Eruption of the Volcano Bezymianny // Bulletin Volcanologique, organe de IAV. 1959. V. 20. V. 2. P. 77-109.
Gigantic directed blast at Shiveluch volcano (Kamchatka) (1970)
Gorshkov G.S., Dubik Y.M. Gigantic directed blast at Shiveluch volcano (Kamchatka) // Bulletin Volcanologique. 1970. V. 34. P. 261-288.
Granulometric composition of pyroclastics from andesite volcanoes of Kamchatka (1995)
Girina O.A. Granulometric composition of pyroclastics from andesite volcanoes of Kamchatka // 5 Zonenshain conference on plate tectonics. Moscow. 1995. P. 11
Great explosive eruptions on Kamchatka during the last 10,000 years: Self-similar irregularity of the output of volcanic products (2003)
Gusev A.A., Ponomareva V.V., Braitseva O.A., Melekestsev I.V., Sulerzhitsky L.D. Great explosive eruptions on Kamchatka during the last 10,000 years: Self-similar irregularity of the output of volcanic products // Journal of Geophysical Research. 2003. V. 108. № B2. doi:10.1029/2001JB000312.    Аннотация
Temporal irregularity of the output of volcanic material is studied for the sequence of large (V ≥ 0.5 km3, N = 29) explosive eruptions on Kamchatka during the last 10,000 years. Informally, volcanic productivity looks episodic, and dates of eruptions cluster. To investigate the probable self-similar clustering behavior of eruption times, we determine correlation dimension Dc. For intervals between events 800 and 10,000 years, Dc ≈ 1 (no self-similar clustering). However, for shorter delays, Dc = 0.71, and the significance level for the hypothesis Dc < 1 is 2.5%. For the temporal structure of the output of volcanic products (i.e., for the sequence of variable-weight points), a self-similar “episodic” behavior holds over the entire range of delays 100–10,000 years, with Dc = 0.67 (Dc < 1 at 3.4% significance). This behavior is produced partly by the mentioned common clustering of event dates, and partly by another specific property of the event sequence, that we call “order clustering”. This kind of clustering is a property of a time-ordered list of eruptions, and is manifested as the tendency of the largest eruptions (as opposed to smaller ones) to be close neighbors in this list. Another statistical technique, of “rescaled range” (R/S), confirms these results. Similar but weaker-expressed behavior was also found for two other data sets: historical Kamchatka eruptions and acid layers in Greenland ice column. The episodic multiscaled mode of the output of volcanic material may be a characteristic property of a sequence of eruptions in an island arc, with important consequences for climate forcing by volcanic aerosol, and volcanic hazard.
 H
H2O and CO2 in parental magmas of Kliuchevskoi volcano inferred from study of melt and fluid inclusions in olivine (2011)
Mironov N.L., Portnyagin M.V. H2O and CO2 in parental magmas of Kliuchevskoi volcano inferred from study of melt and fluid inclusions in olivine // Russian Geology and Geophysics. 2011. V. 52. № 11. P. 1353 - 1367. doi: 10.1016/j.rgg.2011.10.007.    Аннотация
This paper reports new FTIR data on the H2O and CO2 concentrations in glasses of 26 naturally quenched and experimentally partially homogenized melt inclusions in olivine (Fo85–91) phenocrysts from rocks of the Kliuchevskoi volcano. Measured H2O concentrations in the inclusions range from 0.02 to 4 wt.%. The wide variations in the H2O content of the inclusions, which do not correlate with the host olivine composition and contents of major elements in the melts, are explained by the H2O escape from inclusions via diffusion through the host olivine during the magma eruption and the following cooling. The largest H2O loss is characteristic of inclusions from lava samples which cooled slowly after eruption. The minimal H2O loss is observed for inclusions from rapidly quenched pyroclastic rocks. Parental magmas of the Kliuchevskoi volcano are estimated to contain 3.5 wt.% H2O. The new data imply a 40 °C lower mantle temperatures than that estimated earlier for the Kliuchevskoi primary melts. The concentrations of CO2 in glasses range from <0.01 to 0.13 wt.% and do not correlate with the type of studied inclusions and their composition. The calculated pressures of melt equilibria with H2O–CO2 fluid inside the inclusions are lower than 270 MPa. They are significantly lower than a pressure of 500 MPa calculated from the density (~0.8 g/cm3) of cogenetic fluid inclusions in high-Fo olivine. The significant pressure drop inside the melt inclusions after their trapping in olivine might be due to the H2O loss and redistribution of CO2 from melt to daughter fluid phase. Compared with melt inclusions, cogenetic fluid inclusions provide independent information about the crystallization pressures of olivine and initial CO2 content in the Kliuchevskoi magma, which were estimated to be at least 500 MPa and 0.35 wt.%, respectively. The maximum CO2 concentrations in the primary Kliuchevskoi melts are estimated at 0.8–0.9 wt.%. The decompression crystallization of the Kliuchevskoi magmas starts at depths of 30–40 km and proceeds with a continuous decrease in CO2 content and an increase (up to 6–7 wt.%) and then a decrease (at <300 MPa) in H2O content in melts, which explains the origin of the whole spectrum of rocks and melt inclusions of the Kliuchevskoi volcano.
Highly silicic glasses in peridotite xenoliths from Avacha volcano, Kamchatka arc; implications for melting and metasomatism within the sub-arc mantle (2009)
Ishimaru Satoko, Arai Shoji Highly silicic glasses in peridotite xenoliths from Avacha volcano, Kamchatka arc; implications for melting and metasomatism within the sub-arc mantle // Lithos. 2009. V. 107. № 1–2. P. 93 - 106. doi: 10.1016/j.lithos.2008.07.005.    Аннотация
Silicate glasses in peridotite xenoliths from Avacha volcano have high SiO2 (up to 72 wt.) and highly SiO2-oversaturated characteristics; normative quartz content is up to 50 wt.. The glasses represent secondary melts solidified after interaction with mantle peridotite, i.e. crystallization of secondary orthopyroxene at the expense of olivine. We identified two kinds of silicate glasses in Avacha peridotites; one is higher in K2O and enriched in Rb, Ba, U, and Pb than the other. The glasses show basically similar chemical characteristics to the host basaltic andesite to andesite of the Avacha volcano. These chemical characteristics are inherited from slab-derived fluids/melts, which metasomatize the mantle wedge and induce partial melting. The differences of chemical features among the Avacha glasses are attributed to chemical difference of the slab-derived fluids/melts, possibly due to the difference of sediments/basalt ratio of the relevant slab. The low-degree partial melt of peridotite assisted by these fluids/melts, is primarily SiO2-oversaturated, and can conduct silicate metasomatism, evolving through interaction with surrounding mantle peridotite, i.e. formation of orthopyroxene at the expense of olivine. Highly silicic glasses, also reported from peridotite xenoliths from oceanic hotspots and continental rift zones, mostly result from assimilation of orthopyroxene by SiO2-undersaturated melts, which crystallize clinopyroxene and olivine. The glasses also show similar trace-element patterns to their host alkali basaltic magmas, as in the case of arc glasses/calc-alkali magmas. If the glasses in peridotite xenoliths are of silicate metasomatism origin, they are similar in chemistry to host magmas. Reaction between carbonatite melts and peridotites shows the same petrographical feature as that of SiO2-undersaturated silicate melts with peridotites. The glasses originated from carbonatite metasomatism, however, exhibit clearly different trace-element patterns from their host alkali basaltic magmas.
Historical eruptions of Avacha volcano, Kamchatka. Attempt of modern interpretation and classification for long-term prediction of the types and parameters of future eruptions. Part 1 (1737-1909) (1994)
Melekestsev I.V., Braitseva O.A., Dvigalo V.N., Bazanova L.I. Historical eruptions of Avacha volcano, Kamchatka. Attempt of modern interpretation and classification for long-term prediction of the types and parameters of future eruptions. Part 1 (1737-1909) // Volcanology and Seismology. 1994. V. 15. № 6. P. 649-665.    Аннотация
Some of the previous views on the style of the Avacha eruptions during 1737-1909 are revised on the basis of new data obtained by the authors. The types of eruptions, their geological and geomorphological effects, and the related volcanic hazards are reassessed. All eruptions were explosive events, except for the 1894-1895 extrusive-explosive eruption. The eruptions of 1737, 1779, and 1827 are classified as large, the others, as mild or medium-size events. -from Journal summary
http://repo.kscnet.ru/55/ [связанный ресурс]
Historical eruptions of Avacha volcano, Kamchatka. Attempt of modern interpretation and classification for long-term prediction of the types and parameters of future eruptions. Part 2 (1926-1991) (1994)
Melekestsev I.V., Braitseva O.A., Dvigalo V.N., Basanova L.I. Historical eruptions of Avacha volcano, Kamchatka. Attempt of modern interpretation and classification for long-term prediction of the types and parameters of future eruptions. Part 2 (1926-1991) // Volcanology and Seismology. 1994. V. 16. № 2. P. 93-114.    Аннотация
Previous data are summarized and new evidence is presented on the Avacha eruptions of 1926-1927, 1938, and 1945. The last eruption of January 1991 is described. The dynamics of the Avacha eruptive activity is considered for a period of 1737-1991. The eruptions are classified into different types. The type and size of a future event are predicted and the related hazard is assessed. It is recommended that the southwestern and southern sectors of the Avacha surrounding should be declared forbidden for residential or industrial construction because of a high volcanic hazard. -Journal summary
http://repo.kscnet.ru/160/ [связанный ресурс]
Holocene Key-Marker Tephra Layers in Kamchatka, Russia (1997)
Braitseva Olga A., Ponomareva Vera V., Sulerzhitsky Leopold D., Melekestsev Ivan V., Bailey John Holocene Key-Marker Tephra Layers in Kamchatka, Russia // Quaternary Research. 1997. V. 47. № 2. P. 125-139. doi:10.1006/qres.1996.1876.    Аннотация
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 in 14C 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.
Holocene Volcanoes in Kamchatka (2002)
Holocene Volcanoes in Kamchatka. 2002.
Holocene catastrophic caldera-forming eruptions of Ksudach volcano, Kamchatka (1996)
Melekestsev I.V., Braitseva O.A., Ponomareva V.V., Sulerzhitskiy L.D. Holocene catastrophic caldera-forming eruptions of Ksudach volcano, Kamchatka // Volcanology and Seismology. 1996. V. 17. № 4-5. P. 395-422.    Аннотация
Four Plinian eruptions of Ksudach have been reconstructed and dated by the carbon-14 method. The eruptions produced three collapse calderas: the KS1 eruption formed Caldera V 1700-1800 years ago, the KS2 and KS3 events produced Caldera IV 6000-6100 years ago, and the KS4 eruption formed Caldera III 8700-8800 years ago. The most violent eruption was the KS1 event. The sizes of the calderas were 4 × 6.5 km (V), 5 × 6 km (IV), and presumably 2-3 km across (III). Juvenile material was erupted in a rhythmic manner. The composition of the products was dominated by andesite (KS2 and KS4), dacite and rhyodacite (KS3), and rhyodacite (KS1). It is assumed that all caldera-forming eruptions were triggered by the injection of a new portion of high-temperature basic magma and its mixing with the cooling acid magma of the preexisting source. -from Journal summary

Реконструированы и датированы 14С-методом четыре плинианских извержения вулкана Ксудач, сформировавших три кальдеры обрушения: KCi и кальдеру V - 1700-1800 л. н.; КС2 + КС3 и кальдеру IV - 6000-6100 л. н.; КС4 и кальдеру III 8700-8800 л. н. Самым мощным было извержение KCi: 18-19 км3 пирокластики, высота эруптивной колонны до 23 км. Объем продуктов извержений КС2 + КС3 - 10-11 км3, КС4 - не менее 1,5-1,7 км3. Размеры кальдер: V - 4 X 6,5 км, IV - 5x6 км, поперечь III - предположительно 2-3 км. Вынос ювенильной пирокластики в ходе извержений было ритмичным. Каждый ритм начинался выбросом тефры, а завершался формированием пирокластических потоков. Состав продуктов варьировал от андезитов до риодацитов: КС2 и КС4 - преимущественно андезиты, КС3 - дациты и риодациты, KCi - риодацит. Предполагается, что "спусковой механизм" для начала всех кальдерообразующих извержений - внедрение свежей сильно нагретой магмы основного состава и смешение ее с остывающей кислой магмой существовавшего ранее очага. В соответствии со своими масштабами извержения должны были оказать влияние на климат и озоновый слой 3емли и найти отражение в виде кислотных пиков в Гренландском ледниковом щите.
http://repo.kscnet.ru/903/ [связанный ресурс]
Holocene catastrophic lahars at Avacha and Koryakskiy volcanoes in Kamchatka (1996)
Melekestsev I.V., Sulerzhitskiy L.D., Bazanova L.I., Braitseva O.A., Florenskaya N.I. Holocene catastrophic lahars at Avacha and Koryakskiy volcanoes in Kamchatka // Volcanology and Seismology. 1996. V. 17. № 4-5. P. 561-570.    Аннотация
Remnants of five catastrophic lahars have been discovered, described, and dated by the carbon-14 method. They occurred during eruptions of Avacha (violent explosions with voluminous juvenile pyroclastics) and Koryakskiy (large fissure lava flows): 3500 to 3200 14C years ago or 1900-1500 years B.C. These lahars were much higher in vigor, hazard, and effect on the environment than the lahars generated by the historic eruptions of these volcanoes. -from Journal summary
Holocene eruptive history of Ksudach volcanic massif, South Kamchatka: evolution of a large magmatic chamber (1999)
Volynets O.N., Ponomareva V.V., Braitseva O.A., Melekestsev I.V., Chen Ch.H. Holocene eruptive history of Ksudach volcanic massif, South Kamchatka: evolution of a large magmatic chamber // Journal of Volcanology and Geothermal Research. 1999. V. 91. P. 23-42. doi: 10.1016/S0377-0273(99)00049-9.    Аннотация
The combination of geological, tephrochronological and geochemical studies is used to reconstruct the Holocene eruptive history of Ksudach volcanic massif, South Kamchatka and to trace the evolution of its magma. Ksudach is located in the frontal volcanic zone of Kamchatka. From Early Holocene till AD 240, the volcano had repetitive voluminous caldera-forming eruptions. Later they gave way to frequent moderate explosive–effusive eruptions that formed the Shtyubel' stratovolcano inside the nested calderas, and then to frequent larger explosive eruptions. Holocene eruptive products are low-K2O two pyroxene–plagioclase basaltic andesite to rhyodacite. Mineralogical, geochemical and isotopic data suggest that all the rock varieties originated as a result of fractionation of an initial mafic melt, with insignificant contamination and assimilation. Intensive mixing of the fractionating melts prior to, and during the course of the eruptions, is ubiquitous. The eruptions might have been triggered by repetitive injections of new mafic melt into the silicic chamber. Crystallization of the andesitic and rhyodacitic melts is estimated to have occurred at temperatures of 970–1010°C and 890–910°C, respectively, PH2O 1.5–2.0 kbar and fO2 close to the NNO buffer. According to the experimental data, such PH2O corresponds to 4.5%–5.5% of water in the melt, that is close to the content of water in the silicic hornblende-bearing magmas of the rear zone of the Kuril–Kamchatka arc. Hence, we suggest that the transition from pyroxene phenocryst associations of the frontal zone to the hornblende-bearing ones of the rear zone might be interpreted as reflecting higher temperatures of crystallization of the melts from the frontal zone rather than increasing water content in the rear zone magmas.
http://www.kscnet.ru/ivs/bibl/vulk/ksud/jvgr_ks_99.pdf [связанный ресурс]
Holocene eruptive history of Shiveluch Volcano, Kamchatka Peninsula, Russia (2007)
Ponomareva V., Kyle P., Pevzner M., Sulerzhitsky L., Hartman M. Holocene eruptive history of Shiveluch Volcano, Kamchatka Peninsula, Russia // Geophysical Monograph Series. // Volcanism and Subduction: The Kamchatka Region. 2007. V. 172. P. 263-282. № doi:10.1029/172GM19.    Аннотация
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, hornblendebearing 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 (> 18 ppm). Only two mafic tephras erupted about 6500 and 2000 BC, each within the period of most intense activity.
Many past eruptions from Shiveluch were larger and far more hazardous then the historical ones. The largest Holocene eruption occurred ∼1050 AD and yielded >2.5 km3 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 tephra from the Chukchi-Alaskan margin, Arctic Ocean: Implications for sediment chronostratigraphy and volcanic history (2017)
Ponomareva Vera, Polyak Leonid, Portnyagin Maxim, Abbott Peter, Zelenin Egor, Vakhrameeva Polina, Garbe-Schönberg Dieter Holocene tephra from the Chukchi-Alaskan margin, Arctic Ocean: Implications for sediment chronostratigraphy and volcanic history // Quaternary Geochronology. 2017. doi:10.1016/j.quageo.2017.11.001.    Аннотация
Developing chronologies for sediments in the Arctic Ocean and its continental margins is an important but challenging task. Tephrochronology is a promising tool for independent age control for Arctic marine sediments and here we present the results of a cryptotephra study of a Holocene sedimentary record from the Chukchi Sea. Volcanic glass shards were identified and quantified in sediment core HLY0501-01 and geochemically characterized with single-shard electron microprobe and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). This enabled us to reveal a continuous presence of glass shards with identifiable chemical compositions throughout the core. The major input of glasses into the sediments is geochemically fingerprinted to the ∼3.6 ka Aniakchak caldera II eruption (Alaska), which provides an important chronostratigraphic constraint for Holocene marine deposits in the Chukchi-Alaskan region and, potentially, farther away in the western Arctic Ocean. New findings of the Aniakchak II tephra permit a reevaluation of the eruption size and highlight the importance of this tephra as a hemispheric late Holocene marker. Other identified glasses likely originate from the late Pleistocene Dawson and Old Crow tephras while some cannot be correlated to certain eruptions. These are present in most of the analyzed samples, and form a continuous low-concentration background throughout the investigated record. A large proportion of these glasses are likely to have been reworked and brought to the depositional site by currents or other transportation agents, such as sea ice. Overall, our results demonstrate the potential for tephrochronology for improving and developing chronologies for Arctic Ocean marine records, however, at some sites reworking and redistribution of tephra may have a strong impact on the record of primary tephra deposition.





 

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