Establishing chronologies from acid-insoluble organic C-14 dates on Antarctic (Ross Sea) and arctic (North Atlantic) marine sediments

To compare north and south polar marine paleoenvironments over the last 30, 000 years, comparable chronological (radiocarbon) records must be developed and refined, Many areas in the polar regions do not preserve marine carbon ates (foraminifera, mollusks), and thus age determinations, of necessity, a re based on the acid-insoluble organic (AIO) fraction of the sediment. Alth ough AIO ages are problematic and rarely used in the Arctic, they provide r easonable and consistent chronologies for the Ross Sea, Antarctica. AIO dat es are meaningful in the Ross Sea because there are relatively high levels of productivity, good preservation of marine biogenic material in the sedim ent, and little input of terrigenous sediment and old/dead carbon. Event st ratigraphy based upon proxy records of biogenic silica and delta(13)C be us ed to assess the reliability of dw AIO dates and surface age corrections. R econstructed time-series of changes in the biogenic silica content of cores from the western Ross Sea show apparent similarities with the 'classic' de glacial climate sequence of the northern North Atlantic. Once the absolute ages of the antarctic AIO dates are constrained by independently dated reco rds to validate surface age corrections, it will be possible to directly co mpare the timing of events such as ice-rafting events in the sedimentary re cord.