Characterization of late glacial continental dust in the Greenland Ice Core Project ice core

Twelve glacial dust samples extracted from the Greenland Ice Core Project ice core have been characterized in terms of mineralogy, Sr and Nd isotopic composition, and rare earth element concentrations. The ice samples are taken from the Younger Dryas, the Bolling, the Last Glacial Maximum, and both cold and mild glacial periods back to 44 kyr B.P. A comparison with samples from possible dust source areas determines eastern Asia as being the main source area at all times, hereby confirming and extending earlier results (Biscaye et al., 1997). This finding is partly in agreement with recent atmospheric general circulation model simulations of glacial atmospheric dust transport (Andersen et al., 1998; Mahowald et al., 1999). A low intersample variability in tracer characteristics is discussed in the context of a volcanogenic influence, grain size dependence, and variability in the continental dust source areas. The clay mineralogy of the ice core dust shows a weak climatic dependence, while the isotopic composition of Sr and Nd does not correlate with climate. This is interpreted as a geographical variation of source areas on a regional scale within Asia. Two ice dust samples were size-fractionated at 2 mu m, and the grain size dependence on tracer characteristics is in accordance with the literature.