Atmospheric Dust in North Central Greenland Ice: North Grip

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This proposal is to participate in the North GRIP or NGRIP (North Greenland Icesheet Project) deep-core project in North Central Greenland. This effort is begin led by the Danes with participation from scientists from about six other nations. If funded, the U.S. contribution will be in measurements of mineralogical and radiogenic-isotope characteristics of dusts to determine their provenance (this proposal), and in measuring and interpreting stable isotopes (James White, U. Colorado). The principal purpose in drilling this core, as stated by the Danes, was to recover a reliable record of the Eemian from Greenland ice. There is much to be learned beyond this task, however, and much to be gained from this core regardless of the success in recovering an undisturbed Eemian section. This project objectives are: - using mineralogical and Sr-, Nd- and Pb-isotope compositions, to determine the source areas of the atmospheric dusts that have been deposited at NGRIP over the period recorded by the ice core -- hopefully including the Eemian -- thus providing constraints for models of paleoatmospheric circulation and transport from the dust source areas to the NGRIP part of Greenland. - to compare these dust source areas recorded at NGRIP to those recorded at the same times in the dusts at Summit (GISP2, GRIP), and other possible Greenland core sites (e.g., Dye 3), and thus begin to discern degrees of local (Greenland) variability in transport pathways, further constraining circulation models; - if undisturbed Eemian ice is recovered at NGRIP, to specifically compare dusts from that ice to the putative Eemian ice, with any significant variations, at GRIP.