Laacher See tephra discovered in the Bohemian Forest, Germany, east of the eruption

Abstract

Abstract We present a geochemically confirmed finding of the Laacher See tephra (LST), directly east of the Laacher See volcano (LSV). European lake sediment (Rachelsee, Germany) contains the time period of the Laacher See volcanic explosion (LSE) ca. 12900\u202fyr\u202fcal BP in the East Eifel volcanic field. This eruption significantly affected the local environment but its impact in regions far east from its source is poorly known. The lake sediment sequence showed an enhancement in magnetic susceptibility and an increase in concentration in niobium and phosphorus. These enhancements correlated with direct tephra particle observations whose geochemical analysis compared well with the published LST data from proximal sites. Detailed analyses revealed a most likely match with tephra known to have been deposited during the middle phase of the eruption. We suggest that contrary to other published studies, the LST cloud traveled directly east, as far as 470\u202fkm, from the volcano,. The pollen record shows minimal change during the tephra deposition, thus indicating that the LSE had no noticeable influence on vegetation in eastern Bavaria and the southern part of the Czech Republic. The discovery of the LST at Rachelsee, opens the potential of further tephrochronological studies in regions to the east of the LSV.