A 36 Ky record of iceberg rafting and sedimentation from north-west Iceland

Abstract

Evidence from north‐west Iceland's shelf and fjords is used to develop a scenario for environmental change during the last 36 cal Ky. The retreat history of the Iceland Ice Cap during the last deglaciation is delineated through lithofacies studies, carbon analyses and magnetic susceptibility, and studies of ice‐rafted debris (IRD) in sediment cores. Sedimentological data from lake Efstadalsvatn, Vestfirdir peninsula, trace the glacier retreat on land. In two of the high resolution shelf cores we detect near continuous IRD accumulation from 36 to 11 cal Kya. However, IRD is absent in the cores from ca. 22 to 19 cal Kya, possibly indicating more extensive landfast sea ice conditions. All cores show intensified IRD during the Younger Dryas chronozone; the fjord cores show a continuous IRD record until 10 cal Kya. Magnetic susceptibility and carbon analyses from Efstadalsvatn reveal the disappearance of local ice in the basin just before 10.5 cal Kya. No IRD was detected in the sediment cores during 10 to Ø4 cal Kya. Some indication of cooling occurs between 4 and 3 cal Kya, with a fresh input of IRD in fjord cores after 1 cal Kya.

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

“…Relatively warm Atlantic water reached the shelf areas off North Iceland between 18.6-16.3 cal kyrs BP (Table 1;5-6) and the ice sheet retreated from the shelf off West Iceland at 15.0 cal kyrs BP (Table 1;7) (Syvitski et al, 1999;Eiríksson et al, 2000;Andrews et al, 2000;Geirsdóttir et al, 2002). Ingólfsson and Norðdahl (2001) suggested that a rapid rise of global sea level, caused by melting of the large Laurentide, Scandinavian and Barents Sea ice sheets, floated marine based parts of the Icelandic ice sheet and caused its collapse through intensive calving.…”

“…Truncated shorelines also suggest that there was a Younger Dryas expansion of glaciers in West Central Iceland and along the southern (Breiðafjörður) perimeter of Northwest Iceland (Norðdahl and Pétursson, 2005). Sediment cores retrieved from the Ísafjarðardjúp basin in Northwest Iceland reveal expansion of glaciers into the trunk fjord (Geirsdóttir et al, 2002). Promontories along the western and north-eastern coast of Northwest Iceland remained mostly ice-free at the same time (Hjort et al, 1985).…”

The origin of glacial alpine landscape in Tröllaskagi Peninsula (North Iceland)

“…After the glacier retreat at the end of the Younger Dryas, the glacial fronts re-advanced again in the Early Preboreal period, around 11.2 ka (Ingólfsson et al, 1997;Norðdahl and Einarsson, 2001;Norðdahl and Pétursson, 2005). Later, the glaciers retreated rapidly (Kaldal and Víkingssson, 1990;Andrews et al, 2000;Norðdahl and Einarsson, 2001;Geirsdóttir et al, 2002Geirsdóttir et al, , 2009Larsen et al, 2012). By 10.2 ka the centre and north of Iceland was already deglaciated (Stötter et al, 1999;Caseldine et al, 2003).…”

“…During the Allerød stadial, the temperature rose again considerably and the glaciers retreated again (Rundgren, 1995(Rundgren, , 1999Rundgren and Ingólfsson, 1999). During the Younger Dryas the glaciers started to re-advance and in the north and northwest they reached the present coastline and entered the great fiords, in many cases obstructing lateral valleys and forming lakes (Geirsdóttir et al, 2002;Norðdahl and Pétursson, 2005), but many interfluves remained free of ice during this period (Norðdahl and Einarsson, 2001). After the glacier retreat at the end of the Younger Dryas, the glacial fronts re-advanced again in the Early Preboreal period, around 11.2 ka (Ingólfsson et al, 1997;Norðdahl and Einarsson, 2001;Norðdahl and Pétursson, 2005).…”

Timber Logging in Central Siberia is the Main Source for Recent Arctic Driftwood

“…2, part A) was collected from the center of a large sediment drift in Djúpáll Trough (Geirsdóttir et al, 2002;Ólafsdóttir, 2004) that extends from Ísafjardardjúp to the shelf break adjacent to Denmark Strait (Labeyrie et al, 2003;Andrews et al, 2009a;Ólafsdóttir et al, 2010). The site of core 2263 lies beneath the axis of the warm IC.…”