GEOMAGNETIC FIELD PALEOINTENSITY DATING AS A CHRONOLOGICAL TOOL FOR ANTARCTIC HOLOCENE SEDIMENT

We explore the potential to develop and apply geomagnetic field paleointensity dating as a chronological tool for Holocene sediment accumulating on the Antarctic continental shelf. The crux of the method involves tuning the geomagnetic paleointensity record at one’s undated site with an independently dated reference curve. Paleomagnetic analyses of sediment accumulating in fjords and inner-shelf basins on both sides of the Antarctic Peninsula have yielded mixed results. Here we examine the characteristics of sediment that make them suitable or unsuitable for geomagnetic paleointensity dating. We illustrate the success of the method using an example from the Northwest Weddell Sea. We apply the paleointensity dating method to a sedimentary record collected from beneath the former Larsen-A Ice Shelf. This record contains a complete Holocene sequence beginning with the transition from grounded ice to a floating ice shelf and ending with the modern recession of the Larsen-A ice shelf. This approach provides chronological control to a sediment sequence that lack appropriate material for radiocarbon dating. Geomagnetic paleointensity features with wavelengths of 2000-3000 years can be recognized and interhemispherically correlated, illustrating the potential to use geomagnetic paleointensity variations as a long-range correlation tool at sub-Milankovitch time scales.