Abstract

Discriminant function analysis (DFA) of microprobe data on 12 elements in nine Fe oxide mineral types was used to match each Fe oxide grain from an Arctic Ocean core to similarly analyzed grains in probable source areas for ice-rafted detritus. This approach to provenance allows us to determine the proportion of multiple sources with a high degree of statistical probability. Counts of microscopically identified dropstones (> 250 mu m) from centimeter-thick samples of the core and from source-area samples provide a direct link to the sediment source. Multiple types of DFA (e.g., direct vs. stepwise) on the dropstone data provide slightly different sources for many samples from the core. This is due to multiple sources for each core sample and provides a more accurate picture of sources than one DFA procedure alone. Most of the lithic grains were derived from the northwestern Queen Elizabeth Islands centered around Ellef Ringnes Island and from the vicinity of Victoria and Banks Islands. Whereas the microprobe data from individual Fe oxide grains led to these same source areas, they always showed that several sources contributed to each centimeter-thick core sample. Significant input from both the dominant source areas to the same intervals in the core indicates that the ice sheets or ice caps covering these different areas coexisted during several pre-Wisconsin glaciations.

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