Abstrakt
Catastrophic meltwater drainage from glacial Lake Agassiz has been hypothesized as a trigger for large-scale ocean circulation change initiating the Younger Dryas cold reversal. Here we quantify the flood discharge that formed the northwestern outlet of Lake Agassiz using a one-dimensional step-backwater model and a zero-dimension gradual-incision model.
Applying these two independent models, we estimate a peak discharge range of 1.8-2.5 x 10(6) m(3) s(-1) and a flood volume of similar to 21,000 km(3). Such a discharge can only be derived from Lake Agassiz rather than one of the two smaller regional glacial lakes: Churchill or Meadow.
When coupled with existing ice margin chronologies, these results demonstrate that the northwestern outlet of Lake Agassiz provides a viable link for catastrophic meltwater to drain to the Arctic Ocean over a 6-9 month period during the Younger Dryas, though it is unclear whether this was near its beginning.