Late Pleistocene and early Holocene drainage events in the eastern Fehmarn Belt and Mecklenburg Bight, SW Baltic Sea

Abstract

The Fehmarn Belt is a key area for the Late Pleistocene and Holocene development of the Baltic Sea as it was a passage for marine and fresh water during its different stages. The pre‐Holocene geological development of this area is presented based on the analysis of seismic profiles and sedimentary gravity cores. Late Pleistocene varve sediments of the initial Baltic Ice Lake were identified. An exceptionally thick varve layer, overlain by a section of thinner varves with convolute bedding in turn covered by undisturbed varves with decreasing thicknesses is found in the Fehmarn Belt. This succession, along with a change in varve geochemistry, represents a rapid ice‐sheet withdrawal and increasingly distal sedimentation in front of the ice margin. Two erosional unconformities are observed in the eastern Mecklenburg Bight, one marking the top of the initial Baltic Ice Lake deposits and the second one indicating the end of the final Baltic Ice Lake. These unconformities join in Fehmarn Belt, where deposits of the final Baltic Ice Lake are missing due to an erosional hiatus related to a lake‐level drop during its final drainage. After this lake‐level drop, a lowstand environment represented by river deposits developed. These deposits are covered by lake marls of Yoldia age. Tilting of the early glacial lake sediments indicates a period of vertical movements prior to the onset of the Holocene. Deposits of the earliest stages of the Baltic Sea have been exposed by ongoing erosion in the Fehmarn Belt at the transition to the Mecklenburg Bight.

Sub-marine Continuation of Peat Deposits From a Coastal Peatland in the Southern Baltic Sea and its Holocene Development

“…A continuous basal sediment sequence in C3 suggests the autochthonous formation of the sediments, showing sand deposited under freshwater conditions, followed by gyttja deposited during wetland conditions and peat accumulation during the Littorina transgression. Basal peat deposits are frequently used to constrain past sea levels (Lampe and Janke, 2004;Rößler et al, 2011;Heinrich et al, 2017). In principle, the available 14 C ages agree with and support the local Fischland and North Rügen Holocene sea level rise curves (Figure 6) established by Lampe et al (2010), but with a slight tendency toward lower sea level as determined by samples B6.1 and B6.2.…”

Hydroacoustic Mapping of Geogenic Hard Substrates: Challenges and Review of German Approaches

“…12.600-10.300 BP) and organic-rich mud deposited ever since approx. 8.000 BP [51][52][53]. In the North Sea the Saalian lag deposits are partly covered by Holocene marine sands (maximum thickness approx.…”

Geomorphological Data from Detonation Craters in the Fehmarn Belt, German Baltic Sea

“…The lag deposits, a mixture of coarse sand, gravel, and boulders, are residue left-behind material. Fine material was winnowed from the glacial till, which originates from Pleistocene glaciations [30,31]. About 300-500 m further east, a high density of boulders is known.…”