ANTARCTIC (DOME C) ICE-CORE DUST AT 18 KY BP - ISOTOPIC CONSTRAINTS ON ORIGINS

We have determined the source area from which dusts from the Last Glacial Maximum (LGM) section of the Dome C ice core were derived, by comparing their strontium and neodymium isotopic ratios with those of samples from potential source areas. The Sr-87/Sr-86 and Nd-143/Nd-144 isotope ratios of the dusts deposited almost-equal-to 18 k.y. B.P. at the East Antarctic Dome C site were compared with potential Antarctic, Australian, southern African and South American sources. The isotope ratios clearly define the Patagonian provenance of the dust, with the other potential source areas being, at most, minor contributors. Contributions by volcanic ash and tephra to the dust sample were also determined to be minimal, based on the patterns of rare earth elements. Knowing the source of the dusts places constraints on the aeolian trajectory by which it was transported to Antarctica, and this serves as a test of the simulation of southern hemispheric circulation by atmospheric global circulation models during the LGM.