Sedimentological evidence for an early deglaciation in the Weddell Sector at ~19 ka

Existing marine sedimentological constraints on the timing of deglaciation in the Weddell Sector are sparse, owing to the combination of inaccessibility due to thick sea ice, and chronological difficulties typical of Antarctic shelf sediments. Here, we present new results from near the calving line in the Hughes Trough, located in the central-southern Weddell Sea. Ramped pyrolysis 14C dating was used to determine a robust chronology from the 5.0 m long sediment core, PS111_53. The core preserves a full glaciomarine sequence from subglacial, sub-ice shelf, and open marine / polynya environments. The sedimentological transition interpreted to be formed at the grounding zone during ice shelf retreat was dated to 18.2 – 19.0 ka, indicating that grounded ice retreat was underway by this time. Further, the sedimentation rate was drastically reduced at ~6 ka, indicating that the oceanographic and glaciological regimes of the continental shelf may have changed at this time. The proposed timing of glacial mass loss is well placed in the context of recent studies from the continental ice sheet and off-shelf marine sediments, which have suggested that a significant ice mass loss event from the Weddell Sector of the Antarctic Ice Sheet (AIS) may have occurred early in the deglaciation. A synchronous timing of deglaciation between the Weddell Sector of the AIS and Laurentide Ice Sheets during MWP-1A0 points towards bi-polar tele-connections.