Radiocarbon constraints on Antarctic Peninsula Ice Sheet retreat following the Last Glacial Maximum (LGM)

We present marine sedimentologic and radiocarbon data for the timing of retreat of the largely marine-based Antarctic Peninsula Ice Sheet since the Last Glacial Maximum (LGM). Our findings indicate minimum estimates of deglaciation between 18,000 and 9000 calibrated years before present (cal yr BP), roughly in phase with the Northern Hemisphere deglaciation and eustatic sea-level rise. Our findings show this retreat occurred progressively from the outer, middle, and inner continental shelf regions, as well as progressively from the north to the south. Retreat initiated on the outer shelf of the northern Peninsula by ∼18,000 cal yr BP and continued southward by ∼14,000 cal yr BP on the outer shelf of Marguerite Bay, several thousand years earlier than estimated by numeric models. While individual cores yield estimates of glacial retreat that may vary up to ±1100 years, we note steps in the data occur at ∼14,000 and possibly 11,000 cal yr BP, coincidental to rapidly rising (eustatic) sea level, including the well documented melt water pulses (MWP 1a and 1b). These data support the hypothesis that rapidly rising sea level is associated with marine ice sheet destabilization, although additional dates are necessary to substantiate this finding. This study highlights problems with radiocarbon dating acid insoluble organic (AIO) matter in proximal Lateglacial sediments as well as the need for more accurate dating techniques.