The drowned glacial landscape of Kattegat, Denmark

Kattegat constitutes the modern-day connection between the Baltic Sea and the North Sea. This shallow area has been largely influenced by glaciations throughout the Quaternary and sea level has fluctuated since the end of the Last Glacial Maximum (LGM, c. 22 ka BP). In this paper, results and implications of mapping and radiocarbon dating of the shallow subsurface in Kattegat are presented. More than 12,000 km of primarily shallow seismic data have been interpreted, and this regional geological mapping has given new insights into the ice-margin retreat patterns of the Fennoscandian Ice Sheet (FIS), the sedimentary development after the LGM, and sheds light on the drowned palaeolandscape of Kattegat. A total of 392 radiocarbon ages is incorporated in the work, 39 of which are newly obtained ages while the rest have been recalibrated. The ages range from c. 17.7 cal ka BP to modern. Key results of the mapping in Kattegat are the identification of not previously documented glaciotectonic complexes and retreat moraines across Kattegat, a large post-LGM ice-dammed lake in central Kattegat that likely existed from c. 19 to 18 ka BP, an updated relative sea-level curve, new radiocarbon ages, and demarcation of areas that were subaerially exposed during the Early Holocene, and thus, are of marine-archaeological interest. The study fills in the ‘marine gap’ in previous reconstructions of the post-LGM ice-margin retreat and the geological development in southwestern Scandinavia.