Early Holocene glacial lake meltwater injections into the Labrador Sea and Ungava Bay

Abstract

In this paper we analyze drainage routes and estimate fluxes of meltwater released from Labrador-Ungava glacial lakes into the Labrador Sea, Ungava Bay, and Hudson Bay between 7.5 and 6.0 kyr BP (8.4-7.0 calendar (cal) years ka). The analysis and estimates are based on landform-based reconstructions of the Laurentide Ice Sheet (LIS) decay pattern and the associated glacial lake evolution. Geomorphological data constraining the spatial extent of glacial lakes are coupled to a digital terrain model for meltwater volume calculations. The LIS ice recession between 7.5 and 6.0 kyr BP led to the formation of a large number of glacial lakes, which drained in approximately 30 meltwater pulses, with fluxes exceeding 0.015 Sv (1 Sv = 10 6 m 3 s -1), into Labrador Sea, Ungava Bay, and Hudson Bay. The inferred rapid ice margin retreat during late stages of deglaciation indicates that these drainage events were relatively short-lived. The early Holocene glacial lakes of Labrador-Ungava released meltwater, resulting in a total inflow of ∼6000 km 3 freshwater to the North Atlantic. The pulsed nature of meltwater release from the lakes is likely to have resulted in rapid repeated cooling of the Labrador Sea surface water. Copyright 2004 by the American Geophysical Union.