Were the North Atlantic Heinrich events triggered by the behavior of the European ice sheets?

Abstract

Theories explaining the origin and distribution of Heinrich layers—abrupt, massive discharges of ice-rafted detritus—generally attribute these layers to the Laurentide ice sheet. However, doubt has been cast by the discovery that sediments also originated from European ice sheets. Here we present isotopic (Sr-Nd) fingerprints of Heinrich layers obtained in cores from the European margin. They reveal that for most of the Heinrich layers, the icebergs were calved first from the European ice sheets, predating the Laurentide surges. Accelerator mass spectrometry ¹⁴C ages reveal that the oceanic Heinrich events were synchronous with their dust equivalents in the Greenland ice cores, implying a direct ocean-atmosphere link. The typical Laurentide surge seems to have occurred over a short time span, after about 1.5 k.y. of iceberg release from the European ice sheets. This suggests that the Laurentide ice sheet responded to a stimulus created by events in the European sector.