Date of Award

Spring 1997

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Ocean & Earth Sciences

Program/Concentration

Geology

Committee Director

Dennis A. Darby

Committee Member

Frank O. Dudas

Committee Member

G. Richard Whittecar

Committee Member

Jens Bischof

Call Number for Print

Special Collections LD4331.G4 L52

Abstract

Nine Fe oxide mineral types (45pm-250pm) separated from 54 glacial and glaciomarine sediment samples from the Queen Elizabeth Islands (QEI) of Canada were analyzed for 12 elements by electron microprobe to determine the dispersal patterns of ice rafted debris in this area. Both cluster analysis and discriminant function analysis (DFA) on the chemical compositions were used to match each detrital Fe oxide grain to a source The entire QEI area can be subdivided into eight unique areas based on the elemental composition of the Fe oxide minerals. These subdivisions are similar to the source areas based on the assemblage of lithic grain types (>250 pm). The results of matching Fe oxide grains to potential source areas indicate that glacial sediments on the QEI shelf are mixtures from multiple sources. The Nard Hunt Ice Shelf of northern Ellesmere Island was the major source for the QEI shelf off Axel Heiberg Island, especially the outer shelf. Inter-island channels were probably important conduits of ice in the last 20 kyrs and grain compositions from these channels closely match those of the inner shelf. Only small percentages of Fe oxide grains from sources farther from the Arctic Ocean, Devon Island and the Grinnell Peninsula, could be matched to samples from the inter-island channels near the Arctic Ocean. If a large ice sheet covered the QEI (e.g., the Innuitian Ice Sheet), the ice that moved northwestward in these fjord-like channels either did not transport much debris or it melted from the glaciers before reaching the Arctic Ocean. It is possible that these glaciers were cold-based with little entrained debris until they neared the coast, where seasonal melting and refreezing increased their load. Alternatively, because the sediments in these channels closely match the compositions of Fe oxide grains and lithic grain types of nearby islands, the channel ice-rafted detritus (IRD) could be due to small local ice caps and/or the result of shore erosion by sea ice instead of a large ice sheet. In either case, the flowing ice or icebergs of the local glaciers moved northward toward the Arctic Ocean, opposite to modern circulation in these inter-island channels of the QEI. The northern limits of the any ice mass did not extend onto the modern shelf.

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DOI

10.25777/6r8y-a134

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