Recent landscape changes in terminoglacial area of the Nordenskiöldbreen, central Spitsbergen, Svalbard
Abstrakt
Terminoglacial area of the Nordenskiöldbreen is characteristic by abrupt landscape changes caused by recent recession of the glacier and meltwater release. Post-LIA proglacial river system on the right flank of the glacier passed several flow-pattern changes.
According to aerial orthophotos and our field survey, a series of changes from braided to vertically incised channels and vice versa can be recognized. During the ablation season of 2012, the river piracy caused the abandonment of former braided stream to a new perpendicular direction, towards the glacier snout.
This has caused the formation of up to >30 m deep ice-dammed lake. The sedimentary sequences documented in the field support the hypothesis of a river prograding into the lake connected with the rise of the lake level during the formation of the lake.
The sudden subglacial drainage of the lake was followed by vertical incision of a new high-energetic stream several meters into the glaciofluvial and glaciolacustrine sediments and bedrock. Large amounts of fresh, unconsolidated glacigenic, glaciofluvial and glaciolacustrine material in the vicinity of the glacier allowed excellent sedimentological and geomorphological preservation of these events.