Palaeolandscape reconstruction of a shallow coastal embayment in Kattegat, Denmark—influence of sea-level changes during the latest Pleistocene and Holocene

Abstract

Shallow coastal embayments are typical features of former glacial landscapes in parts of Scandinavia and North America. An increasing concern over the impact of accelerating sea-level rise, calls for a better understanding of how coasts respond to sea-level changes. Studying the response of coastal environments, such as submerged embayments, to sea-level changes in the past, can provide important insights into the response of present-day coastlines to future sea-level rise. Kalø Bay is an embayment situated in south-western Kattegat, north of the Aarhus Bay, Denmark. This shallow embayment was influenced by sea-level changes governed by global sea-level rise and glacio-isostatic rebound from the Scandinavian Ice Sheet during the latest Pleistocene and Holocene. In this study, we analyse the palaeolandscape in the bay to identify the depositional succession preserved in the bay and understand the dominant geological processes occurring after the last glaciation in response to sea-level changes. Four major depositional units reflect the variable environment in the bay as it changed from a glacial to proglacial setting through coastal and lagoonal infill stages, and gradually developed into a shallow marine environment as the area was inundated approximately 9–6 cal. ka BP. During a relative sea-level fall in the Mid- and Late Holocene, the deposits in the bay reversed to more coastal facies. Our study highlights the sensitivity of coastal embayments and their dynamic response to sea-level changes. Our results show how the bay changed from a wave-dominated setting in the Early Holocene to a current-dominated setting in the Late Holocene, and how the former glacial landscape and coastal deposits were affected differently by the sea-level rise and associated erosion and redeposition. These results are important for understanding the impacts of future accelerating sea-level rise.