The Early-Mid Holocene transgression (Tapes) at the Norwegian coast - comparing observations with numerical modelling

The Early to Mid-Holocene transgression, dated between approximately 10,000 and 7000 cal yr BP, inundated a significant part of the coastal areas of Norway. In this paper we compare observations of the amplitude of the transgression with numerical modelling. The observations of the transgression along the coast vary from a couple of meters to more than 20 m, and depend on the distance from the margin of the last ice sheet over Fennoscandia. We reviewed and evaluated the uncertainty of the data, and present here the most reliable observations of the transgression - data derived from the analysis of isolation basins - from 17 locations spread along the Norwegian coast. The numerical model simulates the response of the Earth to the deglaciation and changing sea level and shows that the transgression is mainly a result of the rising sea level and movements of the Earth due to postglacial rebound. Our Earth model consists of two viscous layers overlain by an elastic lithosphere. We found a good match to the observations in southern Norway with a weak effective elastic lithosphere (similar to 30 km). This is consistent with a previous study of tilt of the raised late glacial shorelines in southwestern Norway. In northern Norway, however, the same Earth model and ice model give significant mismatch to the observations. The best-fit model for northern Norway has a significantly thicker effective elastic lithosphere. An alternative explanation for the mismatch could be a later deglaciation of the Barents Sea than generally assumed or neo-tectonism in the area. (C) 2020 Elsevier Ltd. All rights reserved.