Identification of tephra horizons in a glacier on the Ushkovsky volcano (Kamchatka)

• Main Authors: N. Gorbach V., T. Philosofova M., V. Mikhalenko N., Н. Горбач В., Т. Философова М., В. Михаленко Н.
• Other Authors: We are grateful to M. V. Portnyagin (GEOMAR Helmholtz Centre for Ocean Research), and V. D. Shcherbakov (Lomonosov Moscow State University) for providing standard samples of volcanic and synthetic glass that allowed us to evaluate the capabilities of analysis on the Vega 3 Tescan instrument. The work was supported by RSF grant 22-17-00159 “Reconstruction of environmental conditions in Kamchatka over the last millennium based on studies of glacial cores and other indirect data”, analytical studies were carried out within the framework of the research project No. 0282-2019-0004 of the Institute of Volcanology and Seismology of the Far Eastern Branch of the Russian Academy of Sciences., Авторы признательны М. В. Портнягину (GEOMAR Helmholtz Centre for Ocean Research) и В. Д. Щербакову (Мг У им. М. В. Ломоносова) за предоставление международных аттестованных образцов вулканических и синтетических стёкол, позволивших оценить возможности анализа на приборе Vega 3 Tescan. Работа выполнена при поддержке гранта РНФ 22-17-00159 “Реконструкция условий окружающей среды на Камчатке за последнее тысячелетие на основе исследований ледникового керна и других косвен ных данных”, аналитические исследования проведены в рамках темы НИР № 0282-2019-0004 Института вулканологии и сейсмологии ДВО РАН.
• Format: Article in Journal/Newspaper
• Language: Russian
• Published: IGRAS 2024
• Subjects: tephra;volcanic glass;ice core;energy dispersive analysis; Ushkovsky volcano;Kamchatka; тефра;вулканическое стекло;ледовый керн;энергодисперсионный анализ; вулкан Ушковский;Камчатка; ice core; Kamchatka; КАМЧАТК*
• Online Access: https://ice-snow.igras.ru/jour/article/view/1362; https://doi.org/10.31857/S2076673424010053

Identification of tephra and its allocation (association) with known eruptive events allows obtainng chronostratigraphic markers, on the basis of which an age scale for dating glacial strata can be developed. To determine the sources of ash in the ice core obtained in 2022 during drilling of glacier in the crater of the Ushkovsky volcano in Kamchatka, the chemical composition of volcanic glass in individual ash particles was analyzed. The accuracy of determination of the volcanic glass composition was verified by analyzing of international standard samples of volcanic and synthetic glass. Based on a comparison of the data we obtained with published data on the composition of tephra glasses from the present-day eruptions in Kamchatka, we determined affiliation of each tephra horizon to specific volcano-source. We have found that the main source of tephra in the ice core of the Ushkovsky Glacier is the Kliuchevskoi volcano, which is the closest and the most productive one among the Kamchatka volcanoes. Ash particles from Bezymyannyi volcano were identified in two horizons. A mixed population of particles was found in one of the horizons, including the ash particles from volcanoes Kizimen, Kliuchevskoi and Bezymyannyi. Analysis of published data on the chronology and distribution of ash plumes from known eruptive events made it possible to confidently correlate the tephra horizon at a depth of 762–777 cm with the initial phase of the eruption of the Kizimen volcano in late 2010–early 2011. Ash from the uppermost tephra buried in the glacier at depths of 89–94 cm belongs to the Bezymyannyi volcano eruption, which the most likely occurred in October 2020. Single particles with rhyolitic composition of glass in the sample from the depth of 348–354 cm may belong to the eruption of the Shiveluch volcano in December 2018. The results of our work can be used on further studying of the ice core from the Ushkovsky volcano, in particular for comparison and correlation with the chronostratigraphic data obtained by ...