Abstract
At the Last Glacial Maximum, Iceland was covered by an ice sheet more than 2000 m thick reaching as far as the shelf break. Rapid deglaciation, controlled by rising global sea level, started between 18.6 and 15.0 cal kyrs BP. In Bølling times, between 15.0 and 14.7 cal kyrs BP, the marine based part of the ice sheet collapsed and glaciers retreated inside the present coastline. At that time Marine Limit (ML) shorelines at very high altitudes were formed. Due to low viscosity of the mantel underneath Iceland, isostatic recovery was very rapid and there is a clear link between deglaciation, glacial unloading and volcanic activity. Following climatic deterioration the ice sheet re-advanced during the Younger Dryas, between 13.8 and 12.0 cal kyrs BP. The advance was terminated near the present coastline as distinct shorelines at lower altitudes than before were formed. In Early Preboreal times, about 11.2 cal kyrs BP, the ice sheet re-advanced once again and a new set of distinct shorelines was formed, at still lower altitudes than before. After that the ice sheet retreated rapidly and relative sea level fell towards and eventually below present sea level, reaching a minimum at -44 m at about 10.0 cal kyrs BP. At about 8.7 cal kyrs BP the ice sheet had disintegrated into individual icecaps of similar extent as the present glaciers.
Highlights
Introduction and terminologyThis paper gives a brief overview of the history of relative sea level changes, deglaciation and environmental changes in Iceland since the Last Glacial Maximum (LGM) and it is primarily based on reviews by Norðdahl and Pétursson (2005) and Norðdahl et al (2008).In our chronology, 14C dates on marine shells are reservoir corrected by 365±20C years [ΔR=24±23], the apparent age for living marine organisms around Iceland (Håkansson, 1983)
As there is a significant difference between these dates post and pre-dating the LGM situation we conclude that it was reached on the Iceland shelf sometimes between 29.1 and 18.6 cal kyrs BP
Due to late Weichselian and early Holocene extensive and extremely rapid environmental changes, the Icelandic ice sheet retreated and extensive areas became ice-free, areas that subsequently were overridden by the ice sheet during repeated late-glacial glacier advances
Summary
This paper gives a brief overview of the history of relative sea level changes, deglaciation and environmental changes in Iceland since the Last Glacial Maximum (LGM) and it is primarily based on reviews by Norðdahl and Pétursson (2005) and Norðdahl et al (2008). C years [ΔR=24±23], the apparent age for living marine organisms around Iceland (Håkansson, 1983). Weighted mean age and standard deviation of dated samples are obtained with the Radiocarbon Calibration Program (CALIB) Rev. 7.0.2 (Stuvier and Reimer, 1993). Age of terrestrial material is calibrated with the data set Intcal (Reimer et al, 2013), and marine material with the data set Marine (Reimer et al, 2013). In this paper ages are reported as calibrated (kilo-) years before present (cal (k)yrs BP =. This paper follows the chronostratigraphical terminology for Norden as proposed by Mangerud et al (1974)
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