Investigating Osmium Isotopes and Sedimentological Records for the end of the Saalian Glacial from Northwest Baffin Bay

Understanding the dynamic response of the Greenland Ice Sheet (GrIS) during past climate warmings is essential for predicting its behaviour as global warming accelerates. However, detailed reconstructions of GrIS growth and retreat are limited due to lack of long high-resolution sedimentary records in proximity to its major glacial outlets. Here, new osmium isotope data are presented, from IODP Expedition 400 Hole U1604B, obtained from the lower slope of the Melville Bugt Trough Mouth Fan on the northwest Greenland margin. The osmium isotope analyses are integrated with shipboard sedimentary proxies to trace sediment sources and reconstruct glacial meltwater flux. Preliminary results from the studied interval show sediment proxy variations suggesting significant changes in sediment sources and depositional conditions. Between ~29 and 24 m CSF-A ¹⁸⁷Os/¹⁸⁸Os are radiogenic (~2.3 – 2.5). In contrast, immediately above this section between ~24 and 22 m CSF-A depth ¹⁸⁷Os/¹⁸⁸Os are distinctly less radiogenic (~1.3). The latter depth interval is also characterized by a peak in Ca/K ratios, decreased magnetic susceptibility and natural gamma radiation. The current preliminary age-model for Hole 1604B suggests that the studied core interval could represent the end of the Saalian Glacial. As such, we hypothesize the change in the sediment proxies is interpreted to record enhanced glacial meltwater and sediment delivery, potentially following ice sheet break-up at the end of the Saalian glacial and transition into the Eemian interglacial. Our multi-proxy findings provide new insight into the relationship between GrIS, Innuitian/Laurentide Ice Sheets, and regional sedimentation patterns during a significant glacial to interglacial transition, with important implications for understanding of GrIS response to abrupt climate warming.