Goltz A.E., Krawczynsky M.J., Gavrilenko M.G, Gorbach N.V., Ruprecht Ph. Evidence for Superhydrous Primitive Arc Magmas from Mafic Enclaves at Shiveluch Volcano, Kamchatka // Contribution to Mineralogy and Petrology. 2020. Vol. 175. P. 115 https://doi.org/10.1007/s00410-020-01746-5.
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% H2O) 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% H2O. 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.
Goltz A.E., Krawczynsky M.J., Gavrilenko M.G, Gorbach N.V., Ruprecht Ph. Petrology and geochemistry of mafic enclaves from Shiveluch volcano, Kamchatka // Goldschmidt2018 Abstract. Boston, USA: 2018.
Gorbach N.V., Philosofova T.M, Portnyagin M.V. Amphibole record of 1964 plinian and following dome-forming eruptions of Shiveluch volcano, Kamchatka // Journal of Volcanology and Geothermal Research. 2020. Vol. 407. № 107108. doi: 10.1016/j.jvolgeores.2020.107108.
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.
Gorbach N.V., Plechova A.A. The lava field in the center of Dzendzur-Zhupanovsky volcanic group, Eastern Kamchatka // Abstract volume of the 8th International Maar Conference, Petropavlovsk-Kamchatsky, Russia, August 24-30, 2020. Petropavlovsk-Kamchatsky: IVS FEB RAS. 2020. P. 58-59.
Gorbach N.V., Plechova A.A., Manevich T.M, Portnyagin M.V., Philosofova T.M, Samoilenko S.B. The Composition of Volcanic Ash and the Dynamics of the 2013–2016 Zhupanovsky Volcano Eruption // Journal of Volcanology and Seismology. 2018. Vol. 12. № 3. P. 155-171. doi: DOI: 10.1134/S0742046318030028.
This paper presents the results from a study of ash compositions that were erupted in 2013–2016.
The juvenile component has been identified in the ejecta using data on the morphology and textural features of ash particles and the composition of volcanic glasses. The data set suggests that the activity of the volcano was phreatomagmatic.
Gorbach N.V., Ponomareva V.V., Pendea I. Florin, Portnyagin M.V. Small but important: new data about activity and composition of Zarechny volcano (Central Kamchatka depression) // 10th Biennual workshop on Japan-Kamchatka-Alaska subduction processes (JKASP-2018). Petropavlovsk-Kamchatsky, Russia, August 20-26. 2018. P. 83-85.
Gorbach Natalia, Portnyagin Maxim, Tembrel Igor Volcanic structure and composition of Old Shiveluch volcano, Kamchatka // Journal of Volcanology and Geothermal Research. 2013. Vol. 263. P. 193-208. doi:10.1016/j.jvolgeores.2012.12.012.
Gordeev E.I., Girina O.A. Volcanoes and their hazard to aviation // Herald of the Russian Academy of Sciences. 2014. Vol. 84. № 1. P. 1-8. doi: 10.1134/S1019331614010079.
In March 2013, the Kamchatkan Volcanic Eruption Response Team (KVERT) celebrated the 20th anniversary of its activity. This team, which was created by the joint efforts of Russian and American scientists, analyzes on a daily basis the data supplied by the complex (seismic, video, visual, and satellite) monitoring system of volcanoes of Kamchatka and the Northern Kuril Islands to notify airline companies and all interested organizations about potential hazards.