The Mjáuvøtn tephra and other Holocene tephra horizons from the Faroe Islands: a link between the Icelandic source region, the Nordic Seas, and the European continent

Abstract

Six different tephra horizons were found in peat and lacustrine sediments on the Faroe Islands in the North Atlantic. Their geochemistry showed that they were of Icelandic origin. Three of these can be correlated with previously described tephra horizons from the Faroe Islands: the Saksunarvatn tephra ( c. 9000 BP), the Hekla-4 ( c. 3800 BP) and Hekla-Selsund ( c. 3600 BP). A previously unrecorded basaltic tephra dated to c. 5700-5300 BP was found in two lacustrine successions. This horizon is named the Mjáuvøtn tephra after Mjáuvøtn Lake on the island of Streymoy. Two further tephras were recorded: the basaltic phase of the ‘Landnám’ tephra (VIIa, c. AD 870s), and the rhyolitic Tjørnuvik tephra. These were found in sediments deposited shortly after the first phase of human settlement at Tjørnuvik, which is AMS dated to AD 675-861 (calibrated age). The Faroe Islands are an important link between the volcanic sources on Iceland, and the established tephrochronological frameworks on the British Isles, Scandinavia and Germany. Their position within a sensitive region of the northeastern branch of the North Atlantic Drift make the Faroe Islands ideal for registering climate changes during the Holocene. The establishment of a modern tephrochronology may provide a tool for more precisely dating and correlating regional climate events in and around the Nordic Seas.