Icelandic volcanic ash from the Late-glacial open-air archaeological site of Ahrenshöft LA 58 D, north Germany

Abstract

Cryptotephra of Icelandic origin from the open-air archaeological site of Ahrenshöft LA 58 D (Kr. Nordfriesland, Schleswig-Holstein), northern Germany overlies a Late-glacial Havelte lithic assemblage, hitherto dated by 14C and biostratigraphy to the earliest part of the Late-glacial interstadial (GI-1e to GI-1c3). Peaks in ash shards are observed in two profiles. Major and minor element geochemistry indicates volcanic ash originating in the Katla system. Precise correlation to previously described tephra is uncertain due to overlapping chemical characteristics. The Ahrenshöft 14C determinations, litho- and bio-stratigraphy encompass a broad age-span for the microtephra-bearing sediments, from the end of the Allerød to the Preboreal. The most plausible volcanic eruption correlates are the Vedde Ash (~Younger Dryas), an Icelandic eruption already known from the European mainland, and the Suduroy tephra (~Preboreal/Boreal), hitherto recorded only in the North Atlantic region. These two ash horizons have been dated to, respectively, 12,171 ± 57 yr b2k in the NGRIP ice-core and c.8000 cal BP, by radiocarbon from the Faroe Isles. Ongoing research on deposits from the type sites for the tephra layers may in the future differentiate these markers leading to better discrimination of the chemistries and a resolution of this question.