Abstract
Abstract. Relative abundance data of diatom (Bacillariophyceae) species were generated for sediment core SKPC-01B from the Skalafjord, Faeroe Islands. The record shows distinct temporal changes in species composition. In the lowermost 65 cm of the 230 cm long core a species-rich freshwater diatom assemblage was found. Most of the taxa observed in this section are typical of oligotrophic to dystrophic lakes in northern Europe (Scandinavia, Iceland and Spitsbergen). Above this interval the diatom flora is dominated by marine taxa. The change from a freshwater to a marine flora is inferred to be caused by rising sea-level that took place about 7700–6400 years BP. Drastic changes in the diatom species composition within the transitional core section show that environmental change in the Skalafjord took place in several pulses. The first stage included strong inflow (possibly catastrophic) of marine waters. As a possible trigger of this phenomenon the tsunami released by the Storegga Slide is proposed. Before the final flooding by marine waters, freshwater conditions were re-established within the Skalafjord. These results have important implications for the interpretation of the palaeogeographical development of the Eysturoy area. Hence, it is suggested that the Storegga Slide led to inflow of marine waters at a distinctly lower water level in the area of the Skalafjord than proposed in recent publications and that the inundation of the threshold in the fjord happened after the tsunami.
Highlights
Fossil diatom floras of freshwater and marine origin may be used for reconstructing environmental changes
MATERIAL AND METHODS Core SKPC-01B was one of nine sediment cores retrieved from the Faeroe Islands during the September–October 1995 R/V Skagerak cruise organized by Göteborg University in collaboration with the Geological Survey of Denmark and Greenland (Fig. 1)
Among the freshwater forms the following taxa were the most abundant: C. rossii, A. distans, A. subarctica, Fragilaria ulna and T. flocculosa
Summary
Fossil diatom floras of freshwater and marine origin may be used for reconstructing environmental changes. Studies of lacustrine sediments from the land areas surrounding the North Sea and Norwegian Sea have been shown to contain a record of past catastrophic events that took place in the area. One such record is a tsunami caused by the Storegga Slide dated at c. Diatoms represent one of the best indicators of the impact of this tsunami on the sedimentary record This phenomenon has been shown to occur in sediment cores from lakes from the Faeroe Islands (Grauert et al, 2001). Post-glacial sediments in the fjord were deposited in two separate basins and have a maximum thickness of about 20 m (Juul, 1992)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
