Late- and postglacial shore level changes in the southwestern Baltic Sea

Abstract

Sub-marine deposits in the region of the Arkona Basin, Mecklenburg Bay and Darss Sill have been studied using a multi-disciplinary approach that includes shallow seismic work, depositional sequence stratigraphy, radiocarbon dating and analyses of diatoms and macrofossils. Models for the relative shore level changes in the two basin areas are proposed. Both in the Mecklenburg Bay basin and in the Arkona Basin maximum shore levels of c. 20 m below present sea level were reached in late Allerød, in late Younger Dryas and in late Preboreal. The drainage of the Baltic Ice Lake led to shore level drops, but in Mecklenburg Bay the drop only amounted to around 5 m, because the Darss threshold hindered further regression. In the Arkona Basin, the drop after the final drainage of the Baltic Ice Lake was approximately 20 m, whereas the water level falls after the Allerød drainage of the Baltic Ice Lake and after the Ancylus Lake maximum, have not yet been determined. The Darss Sill area became a land area with local lakes after the Ancylus Lake drainage; there is no evidence of erosion or fluvial/deltaic sediments in Mecklenburg Bay that could be referred to the proposed so-called Dana River. The evolution of the shore level after the Boreal lowstand is poorly confined by our data, but hydrographic conditions similar to the present were established at c. 7.6 cal. ka BP.