Late Glacial to Holocene volcanism of Jom-Bolok Valley (East Sayan Mountains, Siberia) recorded by microtephra layers of the Lake Kaskadnoe-1 sediments

Abstract

Abstract This article presents first tephrochronological data on the volcanic activity in the valley of the Jom-Bolok River (East Sayan Mountains, Siberia), which is the largest manifestation of the Holocene eruptions in Central Asia. The data results from our study of the proglacial Kaskadnoe-1 Lake situated near the Jom-Bolok basalt field. The lake sediments include a series of tephra-rich layers. Radiocarbon dating of the lake sediments provided a robust age model which allowed us to build timing of eruptions formed the Jom-Bolok volcanic field. We recognize two large phases of volcanism separated by almost 5 thousand years dormant phase. The first phase is traced back to ca. 14.3\u202fcal\u202fka BP and lasted until 6.3\u202fcal\u202fka BP. Ten clusters of microtephra layers in the sediments of the first phase show 300–800\u202fyears recurrence of the volcanic events weakening upward. The event of 14.3–13.3\u202fcal\u202fka BP probably represents the strongest eruptions of the Jom-Bolok. The second phase started ca. 1.6\u202fcal\u202fka BP and highly likely continues in our days. Its strongest eruptions occurred between 1.6 and 0.8\u202fcal\u202fka BP with periodicity of 200\u202fyears. This tephrostratigraphy shows a multiplicity of the Jom-Bolok volcanic events and amplifies the earlier built scheme resulted from investigations of the stratified basalts, pyroclasts and lake damming events. Additionally, we indicate a possible influence of the Jom-Bolok volcanic activity on the regional and global climatic changes.