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Holocene relative sea level history and Storegga tsunami run‐up in Lyngen, northern Norway

2018; Wiley; Volume: 33; Issue: 4 Linguagem: Inglês

10.1002/jqs.3021

1099-1417

Henrik Rasmussen, Stein Bondevik, Geoffrey D. Corner,

Geological formations and processes

ABSTRACT We re‐investigated three isolation basins in Lyngen in Troms, Norway, that contained a mixed facies of terrestrial and marine origin. Here we show that the mixed facies was deposited by the Storegga tsunami. We reconstruct the run‐up of the tsunami to 6–7 m above mean sea level of that time, in agreement with numerical modelling. In addition, our new cores revealed a layer of lake‐gyttja below marine deposits, and radiocarbon ages of plant fragments extracted from that gyttja date the sea level lowstand to 9400 cal a BP. These ages, and our new understanding of the mixed facies as Storegga tsunami deposits, improve the previously published sea‐level curve. The radiocarbon age of a sea urchin, assumed to have been killed in the Storegga tsunami event, shows that the reservoir age of the coastal waters in Troms was 400 years (Δ R = 45 ± 41) at that time − similar to the present‐day value.