Towards a Holocene tephrochronology for the Faroe Islands, North Atlantic

The Faroe Islands hold a key position in the North Atlantic region for tephra studies due to their relative
proximity to Iceland. Several tephras have been described over the last 50 years in peat and lake sediment sequences, including the type sites for the Saksunarvatn and Mj
auvøtn tephras. Here we present a
comprehensive overview of Holocene tephras found on the Faroe Island. In total 23 tephra layers are
described including visible macrotephras such as the Saksunarvatn and Hekla 4 tephras and several
cryptotephras. The importance of tephras originally described from the Faroe Islands is highlighted and
previously unpublished results are included. In addition, full datasets for several sites are published here
for the first time. The Saksunarvatn Ash, now considered to be the result of several eruptions rather than
one major eruption, can be separated into two phases on the Faroe Islands; one early phase with two
precursor eruptions with lower MgO concentrations (4.5e5.0 wt%) than the main eruption and a later
phase with higher MgO concentrations (5.5e6.0 wt%), including the visible Saksunarvatn Ash. The
Tjørnuvík Tephra, previously considered to be a primary deposit, is now interpreted as a reworked tephra
with material from at least two middle Holocene eruptions of Hekla. Several of the tephras identified on
the Faroe Islands provide useful isochrons for climate events during the Holocene.