Multiple Pleistocene ice advances into the Skagerrak: A detailed seismic stratigraphy from high resolution seismic profiles

Abstract

A detailed Pleistocene seismic stratigraphy is proposed for the Skagerrak, an over 700 m deep, elongated depression in the northeastern North Sea. By comparing our high resolution seismic results with those from glacial environments of Canada, Alaska and Antarctica, we conclude that at least during the Weichselian (if not also during the Saalian) a glacier grounded in the eastern Skagerrak and advanced well into its western part as indicated by a thick layer of basal till. The surging glacier truncated the basinal flank of a ridge-like “delta moraine” that was presumably deposited under uniform glacial conditions in an ice-distal environment. The deposition of the Hirtshals Moraine in shallow waters of Hirtshals might originate from a glacier that advanced from Sweden into North Jutland. Soon after the ice withdrawal from the Skagerrak, a layer of well-stratified glaciomarine sediments was deposited over the basal till suggesting floating ice conditions in a fjord-like environment. Due to the rising sea level in the Late Pleistocene, fluvioglacial and shallow marine deposits soon dominated over the glaciomarine sediments, indicating an end of glacial conditions in this region. These post-glacial sediments were first deposited in the western Skagerrak, but as the transgression came to an end in the Mid-Holocene, the depocenter shifted to the east. Today the highest sedimentation rates are found in this eastern part.