Investigation of a possible lead-lag relationship between the Innuitian and Laurentide ice sheets, Arctic Canada

Peaks of iron-rich grains in Arctic Ocean sediment cores matched to the Laurentide and Innuitian Ice Sheets appear to show a lead-lag relationship during the Late Pleistocene when grain abundances are plotted against time and depth below sea floor. Cores from across the Arctic have been analyzed to determine if this is the case. Of the six IRD events identified, the Innuitian leads 68% of the time with 26% of events in all cores occurring simultaneously. The Innuitian seems to lead 33.3% of the time when peaks from the Innuitian and Laurentide occur within close proximity (less than 1 cm), with 41.7% of the Innuitian and Laurentide peaks occurring simultaneously. Innuitian IRD events lasted an average of 1.5 to 3 kyr, while Laurentide events lasted an average of 1.1 to 2 kyr. A particularly well-dated event around 18 ka in PS1230 shows the Laurentide lagging the Innuitian by around 250 years. This short response time suggests that instabilities can be rapidly transmitted from one coalesced ice sheet to another.