Arctic drainage of Laurentide Ice Sheet meltwater throughout the past 14,700 years

A strong outflow event from Lake Agassiz at the end of the Bolling-Allerod plausibly caused the Younger Dryas cold period by an abrupt Arctic freshening, according to geochemical investigation of sediment cores from the Canadian Arctic. During the last deglaciation substantial volumes of meltwater from the decaying Laurentide Ice Sheet were supplied to the Arctic, Gulf of Mexico and North Atlantic along different drainage routes, sometimes as catastrophic flood events. These events are suggested to have impacted global climate, for example initiating the Younger Dryas cold period. Here we analyze the authigenic Pb isotopic composition of sediments in front of the Arctic Mackenzie Delta, a sensitive tracer for elevated freshwater runoff of the retreating Laurentide Ice Sheet. Our data reveal continuous meltwater supply to the Arctic along the Mackenzie River since the onset of the Bolling-Allerod. The strongest Lake Agassiz outflow event is observed at the end of the Bolling-Allerod close to the onset of the Younger Dryas. In context of deglacial North American runoff records from the southern and eastern outlets, our findings provide a detailed reconstruction of the deglacial drainage chronology of the disintegrating Laurentide Ice Sheet.

Automated summary

Geochemical investigation of sediment cores from the Canadian Arctic suggests that a strong outflow event from Lake Agassiz at the end of the Bolling-Allerod period may have caused the Younger Dryas cold period through an abrupt Arctic freshening. The study reveals continuous meltwater supply to the Arctic along the Mackenzie River since the onset of the Bolling-Allerod. Additionally, the research provides a detailed reconstruction of the deglacial drainage chronology of the disintegrating Laurentide Ice Sheet based on deglacial North American runoff records.