Explosive volcanic history of Snæfellsjökull, West Iceland: Geochemistry, chronology and tephra distribution

Abstract

Tephrochronology is firmly rooted in our knowledge of volcanic history. Iceland's Holocene explosive volcanic history is predominantly derived from investigations of soil sections and written archives, following the Norse Settlement c. 877 CE. Unsurprisingly, historically active volcanic provinces are most often the target of these tephrochronological investigations (e.g., Hekla, Katla, Bárðarbunga-Veiðivötn and Grímsvötn). Despite the risk of large explosive eruptions, some volcanic provinces – like Snæfellsjökull have received less attention. While no historical eruptions have been described from the glaciated central volcano, mapping from the late 1960s and early 1980s suggests there have been at least three explosive eruptions (producing silicic tephra) during the Holocene: Sn-1 (∼1.8 ka BP), Sn-2 (∼4.4 ka BP) and Sn-3 (∼8–10 ka BP). The presence of at least two of these tephra layers in European stratigraphic records has been suggested. Furthermore, other (cryptotephra) horizons in Europe exhibit similar geochemical properties to the Snæfellsjökull province, albeit different age estimates than Sn-1, -2, or -3. The tephrochronological potential of Snæfellsjökull tephra is limited by our lack of fundamental knowledge on the volcanic history and the potential range in tephra geochemistry from this stratovolcano. As a step towards addressing this knowledge gap, we present a well-dated record of tephra stratigraphy from lake Laugarvatn, near Snæfellsjökull. Furthermore, we review all Snæfellsjökull-like tephra deposits to improve understanding of Snæfellsjökull's post-glacial explosive volcanic activity affecting both regional and distal environments.