Rapid isostatic rebound in southwestern Iceland at the end of the last glaciation |
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| Authors: | ÓLAFUR INGÓLFSSON HREGGVIDUR NORDDAHL HAFLIDI HAFLIDASON |
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| Institution: | Ólufur Ingólfson, Earth Sciences Centre, Department of Geology, Goteborg University, Guldhedsgutan 5a, S-413 81 Göteborg, Sweden;Science Institute, University of Iceland, Dunhaga 3, Is-107 Reykjavik, Iceland;Geological Institute, University of Bergen, Allégaten 41, N-5007 Bergen, Norway |
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| Abstract: | In connection with a new deglaciation concept for Iceland, implying an extensive glaciation during the Younger Dryas and the decay of the Icelandic inland ice sheet during the Preboreal, the history of relative sea-level changes on Iceland has been re-evaluated. New field data from the Reykjavik area, in Faxaflói Bay southwestern Iceland, were obtained in order to construct the first stratigraphically controlled curve of relative sea-level displacements for Iceland. The curve is constructed on the basis of radiocarbon-dated shells in raised marine deposits and on tephrostratigraphically controlled and radiocarbon-dated, submerged peat deposits. The curve suggests that a post-glacial relative sea-level change of about 45 m, from + 43 m a.s.1. to — 2 m a.s.l, occurred over a period of 900 14C-years in the Reykjavik area between 10 300 BP and 9400 BP. The sea-level curve shows a shoreline displacement of c . 5 cm 14Cyr-1 for that period. The mean absolute uplift rate is calculated to be 6.9 cm 14C yr-1, which is about double the fastest rate reported from any other coastal North Atlantic site. Although this rapid uplift can probably be partly explained by a 14C plateau around the termination of the Pleistocene, it is more than likely controlled by rapid Preboreal deglaciation, together with low asthenosphere viscosities below Iceland and the release of hydroisostatic stresses in connection with the deglaciation. |
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