Sedimentary record of disintegrating ice shelves in a warming climate, Antarctic Peninsula

[1] Seafloor sediments from beneath the former Larsen-A and Prince Gustav ice shelves document the recent breakup of the shelves and provide evidence for interpretation of previous events. At three of five sites, sediment texture coarsens upward with up to 40% sand at the surface. Radiometric Pb-210 dating shows this to have occurred between 1985 and 1993, several years before breakup of the shelf, and that rates of accumulation of sediment on the seafloor doubled to quadrupled during this period. These events are related to the release of eolian sediment in periodic rapid draining of small lakes and crevasses on the ice shelf before breakup. X-ray radiographs of sediment cores also document the recent influx of coarse particles (gravel) related to ice rafting during ice shelf disintegration. Because sediment is released irregularly in time and space from well-separated point sources on the ice shelf during at least several years before final disintegration, only a portion of the seafloor is affected.