Lateglacial to Holocene relative sea-level changes in the Stykkishólmur area, Snæfellsnes peninsula, Iceland

Abstract

Until recently, relatively little scientific research has been undertaken to increase our understanding of relative sea-level (RSL) change in NW Iceland. This study presents the results of diatom, tephra and radiocarbon analyses on five isolation basin and two coastal lowland sediment cores from the Stykkishólmur area, northern Snæfellsnes. The analyses provide an accurate reconstruction of the postglacial RSL changes for the Snæfellsnes peninsula, through the generation of a RSL curve. In addition, the marine limit elevations established for northern Snæfellsnes allow the determination of areas of similar ice thickness within NW. Tephrochronological analyses from sediment cores have allowed the establishment of a potential signature for samples from the Snæfellsnes Volcanic Belt (SVB), as well as the determination of the extent of the Saksunarvatn tephra in Snæfellsnes and internal tephrostratigraphical correlations. In Snæfellsnes, the marine limit is measured at approximately 69 m above sea level, with its formation being estimated at ~ 14000 cal. yrs BP. Following the formation of the marine limit, the rate of RSL change was – 37 mm cal. yr-1 until the isolation of site Saurar 3 at 16.20 m asl in 12558 - 12646 cal. yrs BP, relating to a rate of crustal rebound of + 55 mm cal yr-1 over the same period. Following the isolation of Saurar 3, the rate of RSL fall reduced. During the mid- to late Holocene, RSL fell below present in northern Snæfellsnes, although poor chronological control means that this event can only be tentatively dated to~ 4800 cal. yrs BP. The results highlight the potential of isolation basin, coastal lowland and marine limit data in determining the RSL history for NW Iceland.