Late Weichselian deglaciation pattern in the southwestem Baltic: Evidence from glacial deposits off the island of Møn, Denmark

Shallow seismic investigations and sediment sampling were carried out in the Hjelm and Fakse Bugt (Bay) off the island of M!iin, Denmark. Ribbed moraine morphology is observed in the Hjelm Bugt area while results from seismic studies in Fakse Bugt reveal two different late-glacial sequences: 1; glacial diamict and 2; pro glacial, delta - ice lake and fluvial deposits. These deposits originate from the final Late Weichselian deglaciation. Within sequence 1 two units can be distinguished. Unit l.a consists of glacial deposits dislocated by thrusting that form asymmetrical ridges on the sea floor, unit l .b is not pre-consolidated, (soft) diamict interpreted as supraglacial flow diamict. Sequence 2 can likewise be subdivided in two units a and b. These can be character­ized as delta deposits formed in a glacial lake in which a sudden lowering of the water-level caused a break of the sedimentation. Earlier studies from the Skane area (southern Sweden) report a similar depositional pattern during deglaciation. The deposits consist here of asymmetrical ridges, in­terpreted as Rogen moraines. They were resting on and covered with flow diamict deposits and water layered deposits, thought to have been formed by an arctic glacier with a cold-based compressive marginal zone. From the comparison of onshore glaciotectonic and morphological data with the offshore data presented, it is concluded that the Mons Klint cliff section was formed under glaciotectonic compression between two ice lobes, one from a north-eastern and another from a south-eastern direction. The formation of M!iins Klint was thus associ­ated with a final Weichselian readvance.