Late glacial retreat of the Lancaster Sound Ice Stream and early Holocene onset of Arctic/Atlantic throughflow in the Arctic Island channels

ABSTRACT

Multiple proxies in three sediment cores from Northwestern Baffin Bay document the timing of Lancaster Sound Ice Stream (LSIS) retreat that led to Arctic–Atlantic throughflow in Parry Channel, an important source of freshwater that can impact the Atlantic Meridional Overturning Circulation. The Late Glacial to Holocene timing of ice retreat and channel opening and the responses of the regional ocean environment to these events are presented. We use quantitative mineral composition, foraminiferal assemblages, biogenic silica, ice-rafted debris (IRD), and ¹⁴C-based age models to document and date the events and environmental changes occurring during deglaciation of this major marine channel. Findings show that retreat of the LSIS into Lancaster Sound occurred before ~15.3 cal ka BP, about 800 years before the onset of major iceberg calving events from the LSIS, named the Baffin Bay Detrital Carbonate events (BBDC 1 and BBDC 0). The end of BBDC 0 occurred at ~10.6 cal ka BP, which coincides with the opening of Parry Channel. A marine environment productive of calcareous benthic and planktic foraminifera, with diminished meltwater, seasonal sea ice, warmer summer temperatures, and inflowing, nutrient-rich Arctic surface water characterizes the interval between the opening of Parry Channel and the opening of Nares Strait. Paired planktic and benthic ¹⁴C ages over this 2,200-year interval show diminishing age offsets suggesting progressive mixing of the upper ~850–900 m of the water column. The opening of Nares Strait by ~8.2 cal ka BP coincides with increased biogenic silica in the form of abundant, large centric diatoms and dissolution of CaCO₃. The paucity of calcareous organisms after 8.2 cal ka BP resulted in poor chronological control in the cores to interpret changing environments after 8.2 cal ka BP.

KEYWORDS:

• Deglaciation
• Parry Channel
• BBDC events
• Baffin Bay
• foraminifera

Acknowledgments

We thank Kate Jarrett, GSC-Atlantic, for providing samples and access to data and the GSC core repository. Data generated from this study will be archived in the GSC-Atlantic Expedition database and the U.S. Arctic Data Center. We thank Wendy Roth, CU Boulder and Kate Jarrett, GSC-Atlantic for their help with sampling and sample processing. We thank Professor Marit-Solveig Seidenkrantz and an anonymous reviewer for their helpful comments and suggestions that improved this article.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data Availability Statement

The data that support the findings of this study are openly available in the NSF Arctic Data Center at http://doi.org/10.18739/A2GM81Q31.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/15230430.2022.2110689.

Additional information

Funding

This work was funded by the U.S. National Science Foundation grant OPP P2C2 1804504.