Enhanced iceberg discharge in the western North Atlantic during all Heinrich events of the last glaciation

A series of catastrophic iceberg and meltwater discharges to the North Atlantic, termed Heinrich events, punctuated the last ice age. During Heinrich events, coarse terrigenous debris released from the drifting icebergs was preserved in deep-sea sediments, serving as an indicator of iceberg passage. Quantifying the vertical flux of ice-rafted debris (IRD) in open-ocean settings can resolve questions regarding the timing and spatial variation in ice sheet calving intensity. In this study, Th-230(xs)-based IRD flux throughout the last glacial period was measured in a deep-sea sediment core from the western North Atlantic, and complemented by data spanning 0-32 ka from a sediment core in the Labrador Sea. The cores were recovered from sites downstream from Hudson Strait, a likely conduit for icebergs calving from the Laurentide ice sheet (LIS). We compare our results with equivalent existing data from the eastern North Atlantic and show that the two cores in our study have higher IRD fluxes during all Heinrich events, notably including events H3 (similar to 31 ka) and H6 (similar to 60 ka). This study demonstrates that the LIS played a role in all Heinrich events, and raises the likelihood that a single mechanism can account for the genesis of these events. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study measured higher IRD fluxes during Heinrich events H3 and H6 in deep-sea sediment cores from the western North Atlantic, indicating the potential role of the Laurentide Ice Sheet in all Heinrich events and the likelihood of a single mechanism explaining their genesis.