Abtract:

The Arctic Ocean plays an important role in the global climate system primarily through its influence on Earth’s albedo caused by variations in sea-ice cover, and through the Arctic’s contribution to the formation of the North Atlantic Deep Water (NADW), which is considered to be the main driver of the global thermohaline circulation.

In many cores from the Eurasian side of the Arctic Ocean, a distinct, dark gray layer can be found in the strata roughly corresponding to a time interval around the boundary between Marine Isotope Stages (MIS) 3 and 4. Nd and Sr isotopes are used in combination with clay mineralogy to pin point the source of this layer to the region south of the Kara Sea near the Putorana basalt plateau. The interpretation of the gray layer as the result of an ice-dammed lake-drainage is further supported by biomarker studies showing an enrichment of branched glycerol dialkyl glycerol tetraethers, which are primarily produced in soils. The interpretation of the gray layer as a catastrophic event layer has important implications for Arctic Ocean stratigraphy and for lithostratigraphic correlations across the Arctic Ocean. Furthermore, the huge influx of fresh water to the Arctic Ocean could potentially also have had an important impact on the climate much in the same way as similar ice-dammed lake-drainages from the Laurentian ice shield did during e.g. the Younger Dryas.