Holocene relative sea level changes in the Västervik‐Gamlebyviken region on the southeast coast of Sweden, southern Baltic Sea

Abstract

We reconstruct the Holocene shore displacement of the V€ astervik-Gamlebyviken area on the southeast coast of Sweden, characterised by a maritime cultural landscape and archaeological significance since the Mesolithic. Sediment cores were retrieved from four lake basins that have been raised above sea level due to the postglacial land uplift and eustatic sea level changes after the melting of the Fennoscandian Ice Sheet. The cores were radiocarbon dated and analysed for loss on ignition and diatoms. The isolation thresholds of the basins were determined using LiDAR data. The results provide evidence for the initiation of the first Littorina Sea transgression in this area at 8.5 thousand calibrated years before present (cal. ka BP). A relative sea level rise by 7 m a.s.l. is recorded between 8.0 and 7.5 cal. ka BP with a highstand at 22 m a.s.l. between 7.5 and 6.2 cal. ka BP. These phases coincide with the second and third Littorina Sea transgressions, respectively, in the Blekinge area, southern Sweden and are consistent with the final deglaciation of North America. After 6.2 cal. ka BP, the relative sea level dropped below 22 m a.s.l., and remained at 20 m a.s.l. until 4.6 cal. ka BP coinciding with the fourth Littorina Sea transgression in Blekinge. From 4.6 to 4.2 cal. ka BP, the shore displacement shows a regression rate of 10 mm a 1 followed by a slowdown with a mean value of 4.6 mm a 1 until 1.6 cal. ka BP, when the relative sea level dropped below 3.3 m a.s.l. The Middle to Late Holocene highstand and other periods of minor sea level transgressions and/or higher salinity between 6.2 and 1.7 cal. ka BP are attributed to a combination of warmer climate and higher inflow of saline waters in the southern Baltic Sea due to stronger westerlies, caused by variations in the North Atlantic atmospheric patterns.

Holocene relative shore‐level changes and development of the Ģipka lagoon in the western Gulf of Riga

“…2005) and the onset of the Litorina Sea transgression in the slowly uplifting Västervik–Gamlebyviken (Katrantsiotis et al . 2022), Narva–Luga (Rosentau et al . 2013), Pärnu (Nirgi et al .…”

3000 Years of past regional and local land-use and land-cover change in the southeastern Swedish coastal area: Early human-induced increases in landscape openness as a potential nutrient source to the Baltic Sea coastal waters

“…SE from the lake, close to the northern part of the bay Gamlebyviken, several large grave fields and a Viking Age maritime timber construction are testimonies of an area of particular importance during the Late Iron Age. According to the latest shore displacement curve for the Gamleby area (Katrantsiotis et al, 2023), the shoreline dropped from 11 m a.s.l. at the onset of the Bronze Age down to 3 m a.s.l.…”