M.S. (Master of Science)
Department of Geology and Environmental Geosciences
Glaciers--Antarctica; Antarctica--Environmental conditions; Glaciology
Exploration of an Antarctic glacimarine environment using a remotely operated vehicle (ROV) at the Mackay Glacier has allowed accurate characterization of the sedimentary processes and deposits occurring near the grounding line of a polar marineending glacier. Observations of this environment were utilized with iceberg sampling to quantify the total volume of debris delivered to the grounding line. Sedimentation rates in this environment are used to predict the behavior of Antarctic coastal glaciers during global warming. Detailed description of debris-laden icebergs has established that Mackay Glacier ice occurs in four ice facies. Ice characteristics are unique for each of the facies, indicating that debris incorporation processes vary. Calculations used to determine basal thermal regime along the glacial profile show that debris incorporation is maximized at five locations along the lower 65 km of the glacier. Glacial clast measurements reveal that similar proportions of clast shapes occur in several locations around the Antarctic coast, indicating that glacial processes are similar and consistent around Antarctica. Debris flux for the Mackay Glacier was determined using a glacial “type-section,” representative of the debris concentration profile over the full cross-section of the glacier. A total of 5.5 x 106 m3 a'1 was determined to be the volume of debris delivered to the grounding line. Sediment accumulation rates in this grounding-line environment outpace the predicted rate of sea-level rise caused by oceanic thermal expansion during global warming. Therefore, it appears that the relative water depth at the terminus is being reduced, and sedimentation is a positive influence on stability and glacial advance, even during the initial stages of global warming. Using the debris flux value, an erosion rate of 5.3 mm a'1 was determined for the lower 65 km of the glacier, where most erosion occurs. The observations made using the ROY allowed linkage of glacial processes to their resulting deposits in a sedimentary model that depicts the deposits produced during glacial advance and retreat cycles. This model can be utilized to more accurately interpret the history of the Antarctic Continental Shelf.
McInnes, James N., "Characterization of a polar glacimarine environment : Mackay Glacier, South Victoria Land, Antarctica" (2000). Graduate Research Theses & Dissertations. 1734.
x, 167 pages, maps
Northern Illinois University
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