Late Weichselian history of relative sea level changes in Iceland during a collapse and subsequent retreat of marine based ice sheet

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.

Keywords

• iceland, ice sheet, weichselian, deglaciation, sea level.