A Late Holocene tephra record of the last ±4000 years from Sundneset, Barentsøya, E-Svalbard.

Abstract

With an increase in public interest towards climate science and the high demand for chronological markers correlating palaeo-climatological data from proxies, an accurate timescale is imperative. In this thesis, attention is drawn to tephrochronology: the use of volcanic ashes from known eruptions that act as time equivalent stratigraphic markers. Here, a tephrochronological research on lacustrine sediments from the Svalbard archipelago is outlined. A careful collection was made based on expected tephra horizons. Floating sediments were prepared into microscope slides, in which they were counted. To make use of a secondary independent proxy, diatom fragments were counted with respect to the particle density. An age depth model was constructed on which a loss of ignition profile was plotted. Shard count was plotted relative to this age model, reconstructed from C14 dates. Several tephra and corresponding diatom peaks were found and interpreted: The Hekla-1104, Öraefajökull-1362, Hekla-3 and other not yet interpreted tephra peaks around 850-900 AD and 1400-1500 AD. The resulting LOI-curve reflects the arctic climate of the past 2000 years quite good, indicating that the interpreted ages of tephra peaks are likely to be correct. Possible suggestions were given on the relative abundance of tephra in Higher LOI sections, likely related to warmer climate. The weather pattern footprint on tephra distribution was used to connect periods in time when tephra deposition on Svalbard would be more likely (due to change of average wind direction). More tephrochronological research in Svalbard will be needed, before this region becomes an important transarctic correlating region. This implies that the Svalbard could connect cryptotephra from different source areas (Asia, Europe and North-America).