Postglacial uplift and relative sea level changes in Finnmark,northern Norway |
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Authors: | Anders Romundset Stein Bondevik Ole Bennike |
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Affiliation: | 1. Department of Geology, University of Tromsø, Dramsvegen 201, NO-9037 Tromsø, Norway;2. Sogn og Fjordane University College, Postboks 133, NO-6851 Sogndal, Norway;3. Geological Survey of Denmark and Greenland, Øster Voldgade 10, 1350 København, Denmark;1. Geological Survey of Canada, Atlantic, Natural Resources Canada, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, Canada;2. Department of Earth Sciences, Dalhousie University, Halifax, Nova Scotia, Canada;3. Ocean Mapping Group, University of New Brunswick, Fredericton, New Brunswick, Canada;1. Scott Polar Research Institute, University of Cambridge, Cambridge CB2 1ER, UK;2. Geological Survey of Norway, Trondheim N-7491, Norway;3. Department of Petroleum Engineering and Applied Geophysics, Norwegian University of Science and Technology, Trondheim N-7031, Norway;1. Department of Archaeology, History, Religious Studies and Theology, UiT – Arctic University of Norway, Tromsø, Norway;2. Arctic University Museum, UiT – Arctic University of Norway, Tromsø, Norway;3. Arctic Centre and Groningen Institute of Archaeology, University of Groningen, the Netherlands;1. Department of Earth Science, University of Bergen and Bjerknes Centre for Climate Research, Box 7803, N-5020 Bergen, Norway;2. Geological Survey of Norway, Box 6315 Sluppen, N-7491 Trondheim, Norway;3. Norwegian Geotechnical Institute, Box 3930 Ullevål Stadion, N-0806 Oslo, Norway;1. CAGE, Centre for Arctic Gas Hydrates, Environment and Climate, Department of Geology, UiT The Arctic University of Norway, Norway;2. Department of Geography, Durham University, UK |
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Abstract: | ![]() The outer coast of Finnmark in northern Norway is where the former Fennoscandian and Barents Sea ice sheets coalesced. This key area for isostatic modelling and deglaciation history of the ice sheets has abundant raised shorelines, but only a few existing radiocarbon dates constrain their chronology. Here we present three Holocene sea level curves based on radiocarbon dated deposits from isolation basins at the outermost coast of Finnmark; located at the islands Sørøya and Rolvsøya and at the Nordkinn peninsula. We analysed animal and plant remains in the basin deposits to identify the transitions between marine and lacustrine sediments. Terrestrial plant fragments from these transitions were then radiocarbon dated. Radiocarbon dated mollusk shells and marine macroalgae from the lowermost deposits in several basins suggest that the first land at the outer coast became ice free around 14,600 cal yr BP. We find that the gradients of the shorelines are much lower than elsewhere along the Norwegian coast because of substantial uplift of the Barents Sea. Also, the anomalously high elevation of the marine limit in the region can be attributed to uplift of the adjacent seafloor. After the Younger Dryas the coast emerged 1.6–1.0 cm per year until about 9500–9000 cal yr BP. Between 9000 and 7000 cal yr BP relative sea level rose 2–4 m and several of the studied lakes became submerged. At the outermost locality Rolvsøya, relative sea level was stable at the transgression highstand for more than 3000 years, between ca 8000 and 5000 cal yr BP. Deposits in five of the studied lakes were disturbed by the Storegga tsunami ca 8200–8100 cal yr BP. |
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