Modeling the Production of Heinrich Layers With a Sediment-Enabled Iceberg Model

In the North Atlantic, relatively coarse grained sediments can be found periodically throughout sediment cores spanning the Last Glacial Period. These sediments were rafted by icebergs released from the Laurentide Ice Sheet (LIS) in so-called Heinrich Events. These "Heinrich Layers" coincide with records of global climate change, suggesting that the impact of these events was propagated beyond the North Atlantic. In order to best understand the climate context and significance of Heinrich Events, it is important to constrain the mechanism for their release from the LIS and the nature of the ice sheet itself. One approach for investigating the source of Heinrich Events is to understand the sediment load of icebergs involved, information that would inform interpretations of how those icebergs were produced. By simulating Heinrich Events in a high resolution global climate model (20-40 times the resolution of previous studies), this work investigates the processes involved in the deposition of Heinrich Layers in the North Atlantic. In these simulations, the same volume of sediment is distributed differently through the same volume of icebergs, producing profoundly different sediment records. Due to the high resolution of the model, these simulated sedimentary layers can be inspected in great detail, revealing nuances of the deposit. Only when sediment is distributed throughout the entire iceberg does the model produce a sediment pattern in agreement with observations, yet icebergs with this sediment distribution are not observed in the modern-day.