Application of Tandem Accelerator Mass-Spectrometer Dating to Late Pleistocene-Holocene Sediments of the East Antarctic Continental Shelf

Abstract

AbstractGlacial recession from the Antarctic continental shelf is recorded by glacial-marine diamictons, sands, and overlying siliceous oozes. In order to clarify the chronology for this sequence, use was made of the University of Arizona tandem accelerator mass-spectrometer (TAMS) for 14C dating. Small samples of benthic and planktonic foraminifera were selectively removed from diamictons, graded sands, and surface sediments which were recovered from the Wilkes Land continental shelf and slope, East Antarctica. Organic carbon was also utilized as a source for TAMS dating of the siliceous oozes and muds. Uncorrected ages varied from 14,260 ± 140 to 3230 ± 200 yr B.P. Carbon fixed by phytoplankton and foraminifera is strongly influenced by old, glacial-derived CO2. Thus, reservoir corrections of up to 5500 yr are needed for the 14C dates. Iceberg turbation reworks foraminifera so that dates from resulting deposits (diamictons) are interpreted as maximum ages. The consistency of corrected ages from the shelf, along with the sedimentologic interpretation, suggests a rather recent recession, perhaps mid-Holocene for this portion of the East Antarctic ice sheet. Further application of the TAMS method should help clarify other problems concerning the late Quaternary glacial history of Antarctica.