Chronology of detrital carbonate events in Baffin Bay reveals different timing but similar average recurrence time of North American-Arctic and Laurentide ice sheet collapse events during MIS 3

Baffin Bay Detrital Carbonate (BBDC) layers represent periods of elevated discharge of terrigenous sediments, icebergs and freshwater originating from the North American Arctic-ice sheet complex. Distinct from Heinrich event layers in their dolomitic composition, these sedimentary deposits are found throughout Baffin Bay. They are considered a signature of large-scale instability of the ice sheets discharging into the Baffin Bay, akin to the Heinrich events of the North Atlantic. However, the precise timing of and potential forcing mechanisms for the North American Arctic-ice sheet instabilities remains elusive. Previous work suggests that BBDC events were not in phase with Heinrich events originating from the Hudson Strait, but this hypothesis could not be tested without rigorous chronological constraints. By combining radiocarbon ages and relative paleointensity (RPI) dating in a central western Baffin Bay marine sedimentary sequence, we were able to derive a new chronology for BBDC events covering a large part of MIS3. Sedimentological and elemental data indicate the occurrence of seven distinct BBDC events over the last 52 ka. These events occur during both glacials (stadials) and interglacials (interstadials) and have no consistent phase relationship with Heinrich events. However, the mean duration and mean recurrence time of BBDC events appears similar to Heinrich events. We conclude that BBDC events reflect repeated ice sheet instability periods, with similar statistical properties but different timing compared to the Heinrich events. This implies that episodic instability was an intrinsic property of the North American Arctic-ice sheet complex as well, but over the studied period of MIS3, instabilities of the Arctic and the Laurentide Ice sheets did not appear to have been linked.