Holocene history of the Larsen-A Ice Shelf constrained by geomagnetic paleointensity dating

A sedimentary record collected from beneath the former Larsen-A Ice Shelf reveals the Holocene history of the Larsen-A region. The record begins with the transition from grounded ice to a floating ice shelf, completed by 10.7 +/- 0.5 ka, and ends with the modern recession. The record contains several late Holocene diatomaceous ooze layers that suggest proximity to productive open-water events. Radiocarbon ages obtained from these sediments were compticated by the presence of detrital and reworked carbon. We have eliminated these complications and constructed a chronology for the Larsen-A Ice Shelf history via tuning of the geomagnetic field paleointensity record with a reference curve. This approach provides chronological control to sediment sequences that lack appropriate material for radiocarbon dating. Geomagnetic palleointensity features with wavelengths of 2-3 k.y. can be recognized and interhemispherically correlated, illustrating the potential to use geomagnetic palleointensity variations as a global correlation and dating tool at sub-Milankovitch time scales.