CHERNYI YAR REFERENCE SECTION OF HOLOCENE ASH MARKERS AT THE NORTHEASTERN COAST OF KAMCHATKA

Abstract

A tephrochronological study and radiocarbon dating of soil-pyroclastic sequences were carried out along a profile of Shiveluch Volcano-Chernyi Yar-Bering Islands. Ashes deposited by the largest Shiveluch eruptions (for the last 6500 years) were discovered and identified in the southeastern sector of ash dispersal. Ashes of the Bezymyannyi, Ksudach, Klyuchevskoi, and Khangar volcanoes were identified. The detailed dating of the Chernyi Yar peat bog helped to improve the timing of the eruptions and estimate the ash fall frequency for the area of the lower reaches of the Kamchatka River: one ash fall per 191 years. In addition to the 1964 Shiveluch Tephra, the following ash layers are proposed to be used as regional geochronological markers (ages in years are given in the parentheses): SH1 (265), SH2 (295), SP (1450, 2800, and 3600), and SHdv (4105) of SHiveluch, and also KS1 (1806) of Ksudach and AV2 (5489) of Avacha Volcano.