Geochemical constraints on the Laurentide Ice Sheet contribution to Meltwater Pulse 1A

Planktonic and benthic delta O-18 records adjacent to the runoff outlets of the Laurentide Ice Sheet (LIS) indicate that the LIS contributed to the abrupt similar to 20 m rise in sea level similar to 14.6 ka, Meltwater Pulse 1A (MWP-1A). However, the magnitude of the LIS contribution still remains unresolved. Here, I use a freshwater runoff-ocean mixing model to calculate the LIS meltwater required to explain the decreases in planktonic and benthic 6180 observed during MWP-1A at the southern, eastern and northern runoff outlets of the LIS. Maximum LIS contributions in equivalent sea level rise for a 500-year long MWP-1A are 2.7 m discharged into the Gulf of Mexico as a combined hyperpycnal and hypopycnal flow, 2.1 m discharged into the North Atlantic, and 0.5 m into the Arctic Ocean, for a total LIS contribution of <= 53 m. A LIS contribution of <30% to MWP-1A supports the hypothesis that a significant component of this MWP was sourced from the Antarctic Ice Sheet. (C) 2009 Elsevier Ltd. All rights reserved.