Relative sea level changes in southeastern Sweden the last 6ka mapped by paleo-shorelines.

Abstract:

Emerged Holocene paleo-shorelines, formed during sea level high-stand periods are mostly morphological prominent and thus relatively easily identified in the field. In the study area of southeastern Sweden sediment stratigraphic investigations were used to identify and define the vertical extent of two Baltic Sea transgressive events. In-between these geographically spread study areas, the paleo-shorelines of these transgressive stages were mapped at places they were distinct, well developed and believed to be closely related to paleo sea level. The main factors determining formation of distinct shore-lines is exposure to the open sea and ample supply of erodible coarse grained minerogenic material.

The paleo-shorelines were traced and their absolute elevation established with the help of detailed LIDAR based shaded digital terrain models. These models were derived from the detailed LIDAR point cloud recently made available by the National Land Survey of Sweden. Additionally the paleo-shorelines were confirmed during field visits and details such as sedimentary composition were noted. One of the more difficult variable to determine, the paleo-sea level stand in relation to the shoreline were accessed also in field and related ground surfaces without tree canopies were GPS mapped. The absolute paleo sea level was later derived from the LIDAR ground surface model for these spots.

The c. 6ka shoreline, which is not fully synchronous throughout the whole study area, shows a rather smooth rise from c. 7 m a.s.l. in the south to more than 30 m a.s.l. in the north. Comparison between the 6 ka and the 10.5 ka paleo-shoreline, formed in the Ancylus Lake, further emphasize the glacioisostatic imprint of the Scandinavian ice sheet, but also reveals uplift irregularities, probably of neo tectonic origin.