Khubunaya S.A., Eremina T.S., Sobolev A.V. The classification of potassium basaltic trachyandesites that were discharged by the 2012–2013 parasitic eruption on Ploskii Tolbachik Volcano, Kamchatka using geochemical criteria // Journal of Volcanology and Seismology. 2016. V. 10. № 1. P. 33-49. doi: 10.1134/S0742046316010024.
Annotation
Abstract—This study is concerned with the petrographic, mineralogic, and geochemical features in the K-high basaltic trachyandesites that were discharged by the 2012–2013 parasitic eruption on Ploskii Tolbachik Volcano. These K-high basaltic trachyandesites exhibit some obvious characteristics that testify to their suprasubduction origin. They are deeply differentiated rocks with strongly fractionated plagioclase.A study of the Sr, Nd, and Pb radiogenic isotope ratios in the K-high basaltic trachyandesites provided evidence of their mantle origin and of the fact that the crust has exerted no influence on their compositions. We performed a comparative analysis of the ratios of the concentrations for some incoherent elements in the K-high basaltic trachyandesites, as well as in intraplate, riftogenic, and island-arc moderate potassium basalts and basaltic andesites in relation to the concentrations of these elements in the primitive mantle. The geochemical features of these K-high basaltic trachyandesites classify them as belonging to the suprasubduction subalkaline formation of the potassium series.
Изучены петрографические, минералогические и геохимические особенности К-трахиандезибазальтов побочного извержения 2012–2013 гг. вулкана Плоский Толбачик. К-трахиандезибазальты имеют явные признаки надсубдукционного происхождения. Это глубоко дифференцированные породы, характеризующиеся значительным фракционированием плагиоклаза. Изучение радиогенных изотопных отношений Sr, Nd и Pb в К-трахиандезибазальтах свидетельствует об их мантийном происхождении и отсутствии влияния земной коры на их составы. Проведен сравнительный анализ отношений содержаний некогерентых элементов в К-трахиандезибазальтов,внутриплитных,рифтогенных и островодужных умереннокалиевых базальтах и андезибазальтах к содержанию этих элементов в примитивной мантии. Геохимические особенности К-трахиандезибазальтов позволяют отнести их к надсубдукционной субщелочной формации калиевого ряда.
Melnikov Dmitry, Malik N., Kotenko T., Inguaggiato Salvatore, Zelenski M. A New Estimate of Gas Emissions from Ebeko Volcano, Kurile Islands // Goldschmidt Conference. 26 June - 1 July, Yokohama, Japan. 2016. P. 2047
Annotation
Concentrations and emission rates of major gas species were measured in August 2015 at Ebeko volcano, a quiescently degassing andesitic volcano on Paramushir Island, Northern Kuriles. Using mobile and scanning DOAS measurements we estimated SO 2 emission from the active crater of the volcano at 100 +36/-15 t/d. Based on the comparison of plume areas of individual fumaroles, ca. 90% of the total gas emission from Ebeko in 2015 was provided by a single powerful vent (" Active Funnel " fumarole) and the rest was shared among low-temperature fumaroles. At the time of measurements, gases from the main fumarole had temperature from 420 to 490 °C and composition close to the average arc gas [1], as shown in Table. Gas species CO2 SO2 H2S HCl H2O T, °C mmol/mol Main fumarole 27.9 23.5 6.1 5.6 936 420 Low-temp. jets 92.2 2.62 0.68 1.6 902 <120 Low-temperature fumaroles (<120 °C) emitted gas enriched in CO 2 (up to 28 mol%, 9.2 mol% on average). Such CO 2 enrichment together with depletion in HCl and sulfur species can be explained by scrubbing of soluble gas species by a well-developed hydrothermal system which discharges ultra-acid SO 4-Cl waters [2]. A weighted-average estimate of the total gas+vapor emission from the Ebeko summit provided 1470 t/d, which includes ~ 101 t/d SO2, ~ 110 t/d CO2, ~ 14 t/d H2S and HCl, and 1230 t/d of water vapour with > 50% of the magmatic component. The gas fluxes measured in August 2015 using DOAS fall into the range of previous measurements made from 1960 to 2012 that used direct methods [2] and correspond to the moderate degassing rate of the volcano.
Nishizawa T., Nakamura Hitomi, Churikova T., Gordeychik B., Ishizuka Osamu, Haraguchi Satoru, Miyazaki Takashi, Vaglarov Bogdan S., Ueki K., Toyama C., Iwamori Hikaru Geochemistry of high-Mg andesitic rocks in NE Kamchatka // V.M. Goldschmidt Conference, Yokohama, Japan, 26 June - 1 July 2016. Program and Abstracts. 2016. P. 2295
Annotation
The northeast Kamchatka Peninsula is characterized by unique tectonic regimes: (i) the triple junction ~30 km off the east coast [1], (ii) subduction of the Emperor Seamount Chain [2], and (iii) possible asthenospheric flow between the mantle wedge and the sub-slab mantle via the edge of subducted Pacific slab [3]. Within this area, a monogenetic volcanic group occurs along the east coast, including high-Mg andesitic rocks and relatively primitive basalts (East Cones, EC [4]). We have conducted geochemical studies of the EC lavas, with bulk rock major and trace elements, Sr-Nd isotopic compositions, and K-Ar and Ar-Ar ages, based on which a possible contribution of subducted seamounts and its relation to the tectonic setting are discussed.
The elemental and isotopic compositions indicate that the lavas from individual cones have distinct mantle sources with different amounts and/or compositions of slab-derived fluids. Based on mass balance, water content and melting phase relations, we estimate the melting P-T conditions to be ~1200 ℃ at 1.5 GPa, while the slab surface temperature is 620 – 730 ℃ (at 50-80 km depth). The Sr-Nd isotopic compositions is close to Late Cretaceous Emperor Seamount Chain, especially Detroit [5]. The K-Ar and Ar-Ar ages of the Middle to Late Pleistocene are consistent with the present tectonic setting after 2 Ma [6].
These results suggest that the EC lavas including high-Mg andesite and basalt were generated by mantle flux-melting induced by dehydration of a subducted seamount inheriting a local thermal anomaly [7, 8]
Nishizawa Tatsuji, Nakamura Hitomi, Churikova T., Gordeychik B., Ishizuka Osamu, Iwamori Hikaru Genesis of Quaternary volcanism of high-Mg andesitic rocks in the northeast Kamchatka Peninsula // Japan Geoscience Union Meeting. 22-26 May 2016, Makuhari, Messe. 2016. P. SVC48-02.
Annotation
Arc magmatism is a product of subduction factory, involving thermal and chemical interactions
between a subducted slab as a material input and mantle wedge as a processing factory. In turn, the
compositions of arc magma provide invaluable information concerning the material input and the
interactions. The northeast Kamchatka Peninsula is an ideal field to examine such interactions and
relationships, being characterized by (1) subduction of the Emperor Seamount Chain (Davaille and
Lees, 2004), and (2) possible material and thermal interaction among the subducted slab, the
overlying mantle wedge and the sub-slab mantle via the edge of subducted Pacific slab (Portnyagin
and Manea, 2008). Within this area, a monogenetic volcanic group occurs along the east coast,
including high-Mg andesitic rocks and relatively primitive basalts (East Cones, EC (Fedorenko,
1969)). We have conducted geochemical studies of the EC lavas, with bulk rock major and trace
elements, and K-Ar and Ar-Ar ages, based on which a possible contribution of subducted seamounts
and its relation to the tectonic setting are discussed.
The elemental compositions indicate that the lavas from individual cones have distinct mantle
sources with different amounts and/or compositions of slab-derived fluids. Based on mass balance,
water content and melting phase relations, we estimate the melting P-T conditions to bet ~1200 ℃
at 1.5 GPa, while the slab surface temperature is 620 –730 ℃ (at 50-80 km depth). Compared with
the southern part of Kamchatka, the slab surface temperature beneath EC seems to be high due to the
thinner Pacific slab associated with the seamount chain and/or the plate rejuvenation from a mantle
plume impact (Davaille and Lees, 2004; Manea and Manea, 2007).
The K-Ar and Ar-Ar ages of the Middle Pleistocene are consistent with the tephrochronological
study (Uspensky and Shapiro, 1984) and the present tectonic setting after 2 Ma (Lander and Shapiro,
2007). The high-Mg andesite with the highest SiO2 content in the EC lavas shows the oldest age
(0.73 ±0.06 Ma) within not only EC but also the northeast part of Kamchatka (e.g., Churikova et
al., 2015, IAVCEI). On the other hand, the rest of EC lava samples show relatively younger ages to
0.18 ±0.07 Ma. These results suggest that the EC lavas including high-Mg andesite and basalt were
generated by mantle flux-melting induced by dehydration of a subducted seamount inheriting a local
thermal anomaly (Nishizawa et al., 2014, JpGU; 2015, JpGU).
Romanova I.M., Girina O.A., Maximov A.P., Vasiliev S.E. Integration of volcanological data in VOKKIA information system // Modern Information Technologies in Earth Sciences. Proc. of the VI International Conference, Yuzhno-Sakhalinsk, August 7-11, 2016. Vladivostok: Dalnauka. 2016. P. 65-66.
Sorokin A.A., Girina O.A., Korolev S.P., Romanova I.M., Efremov V.Yu., Malkovskii S., Verkhoturov A., Balashov I. The system of computer modeling of ash cloud propagation from Kamchatka volcanoes // 2016 6th International Workshop on Computer Science and Engineering (WCSE 2016). Tokyo, Japan: 2016. V. II. P. 730-733.
Sorokin A.A., Korolev S.P., Romanova I.M., Girina O.A., Urmanov I.P. The Kamchatka volcano video monitoring system // 2016 6th International Workshop on Computer Science and Engineering (WCSE 2016). Tokyo, Japan: 2016. V. II. P. 734-737.
Аникин Л.П., Блох Ю.И., Богданова О.Ю., Бондаренко В.И., Долгаль А.С., Долгая А.А., Жулёва Е.В., Малиновский А.И., Колосков А.В., Новиков Г.В., Новикова П.Н., Палуева А.А., Петрова В.В., Пилипенко О.В., Рашидов В.А., Романова И.М., Трусов А.А., Федоров П.И., Чесалова Е.И. Новые данные о строении подводных вулканов, гайотов и вулканических островов западной части Тихого океана // Материалы XIX региональной научной конференции «Вулканизм и связанные с ним процессы», посвящённой Дню вулканолога, 29 - 30 марта 2016 г. Петропавловск-Камчатский: ИВиС ДВО РАН. 2016. С. 3-11.
Annotation
Приводятся новые данные о строении подводных вулканов, гайотов и вулканических островов западной части Тихого океана, полученные в рамках интеграции ученых различной специализации академической, вузовской и отраслевой науки в области наук о Земле при проведении комплексных геолого-геофизических исследований в 2015-2016 гг.
Артамонов А.В. Подводные горы системы поднятий Маркус-Неккер (Тихий океан): особенности строения и магматизма // Вестник КРАУНЦ. Серия: Науки о Земле. 2016. Вып. 31. № 3.
Annotation
Проведенное сравнение особенностей вулканизма гайотов мелового возраста, расположенных в разных частях протяженной системы внутриплитных поднятий Маркус-Неккер в Тихом океане, выявило значительные различия в геохимических характеристиках, слагающих их пород, что указывает на существование латеральной и (или) вертикальной мантийной неоднородности в этом регионе. Исследованные вулканические породы относятся к щелочным сериям. В отдельных случаях, в них наблюдается низкие значения Na2O/K2O. Подобный вулканизм не характерен для большинства других внутриплитных поднятий Мирового океана. Отчетливых закономерностей между составом вулканических пород того или иного гайота, временем его формирования и (или) географическим положением не наблюдается. Незакономерное расположение разновозрастных подводных гор создает трудности при применении модели горячих точек для объяснения образования этой провинции внутриплитного магматизма. Положение подводных гор в структуре системы поднятий и всей этой системы в структуре дна Тихого океана не противоречит предположению об их связи с закономерной сетью разломных зон. Разломы способны инициировать плавление геохимически неоднородного верхнемантийного субстрата и приводить к формированию внутриплитных вулканических поднятий. Предполагается, что глубинные флюидные потоки могут быть еще одним фактором, приводящим к масштабному внутриплитному магматизму.
The paper presents geological and geochemical characteristics of Cretaceous guyots of Marcus-Necker intraplate rise in the Pacific Ocean. Comparison of guyots located in different parts of the extended system revealed significant differences in their geochemical characteristics, which suggest lateral and (or) vertical mantle heterogeneity in the region. The studied volcanic rocks belong to the alkaline series. In some cases, they exhibit low values of Na2O/K2O. This volcanism is not typical for most of intraplate ocean rises. No consistency is observed between volcanic rock composition of guyots, their age and (or) geographic position. A complex pattern of magnetic anomaly lineations and irregular location of seamounts of different age cause difficulties in applying hot spot model to explain the formation of this intraplate magmatic province. The location of seamounts in the structure of the rise system and the entire system in the structure of the Pacific Ocean does not contradict the formation of fault zones, which initiate melting of upper mantle geochemically inhomogeneous substrate and lead to the formation of intraplate rises. Deep fluid flows may cause a large-scale melting of the upper mantle.
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