A new coastal ice-core site identified in Dronning Maud Land, Antarctica, for high-resolution climate reconstructions to the Last Glacial Maximum

Abstract

High-resolution ice cores from the Antarctic Ice Sheet margin are crucial for reconstructing the climate history of Antarctica and the Southern Ocean. Ice-rise summits with stable positions and substantial snow accumulation can be ideal sites for such ice cores. We surveyed two ice rises at 16° E, at the eastern edge of the Lazarev Ice Shelf. Kupol Verbljud (VER) is an isle at the calving front, and Kamelryggen (KAM) is a promontory landward of VER. Radar survey reveals ice thicknesses of 560 m under VER's summit and 525 m under KAM's summit. The long-term stable englacial features, Raymond Arches, are observed in both ice rises, but while VER's arches are tilted, KAM exhibits vertically-aligned arches within its summit, indicating a more stable summit position. We find KAM's summit area better suited for a long ice core, given its gentler bed slope and simpler ice stratigraphy. Surface mass balance derived from dated reflectors show consistent spatial patterns over recent decades. Using a one-dimensional age-depth model we consider the local ice flow as a combination of two extreme cases: diverging divide flow and shear-dominated flank flow. We determine which combination of these flow regimes best reproduces the mapped englacial radar stratigraphy and use it to estimate the age of ice. We conclude that KAM's summit is well-suited for obtaining a high-resolution ice core record beyond the Last Glacial Maximum with expected ~20 kiloyear-old ice at a depth 80 m above the bed where the resolution is expected to be 2.5 a cm^-1.