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

Abstract

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 complicated 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 paleointensity features with wavelengths of 2–3 k.y. can be recognized and interhemispherically correlated, illustrating the potential to use geomagnetic paleointensity variations as a global correlation and dating tool at sub-Milankovitch time scales.