An Investigation Into the Processes of Entrainment, Transportation and Deposition of Debris in Polar Ice, With Special Reference to the Taylor Glacier, Antarctica

Abstract

In the present study two separate, but interdependent lines of evidence contribute to an understanding of debris behaviour within Taylor Glacier. The evidence comes from: (i) the thermal regime of the glacier; and (ii) features of the debris within the glacier. The main purpose of studying the thermal regime in the basal ice of Taylor Glacier was to provide information about the likely entrainment and transportation of debris occurring at the glacier sole. Assuming steady-state conditions, the distribution of basal temperatures for Taylor Glacier was determined from the rate of geothermal heat influx at the base of the ice, the temperature near the ice surface, the vertical components of velocity within the glacier, and the ice thickness. The calculated temperature distributions indicate that in over 50 percent of the lower ablation area, the basal ice is at pressure melting. An investigation of englacial and basal debris features led to the conclusion that this material was incorporated by two separate processes operating at the glacier sole. The englacial debris was incorporated by pressure melting and regelation (involving particles), and incorporation of the basal debris was by freezing model regelation (involving blocks) These processes probably occur close to the glacier margin, where the inner warm basal ice is in contact with the marginal cold ice. Here the debris is frozen to the sole and remains relatively unmodified during transport to the margin - the site of deposition. Both lines of evidence indicate that Taylor Glacier is, and has been, capable of capable erosion and entrainment of debris at the glacier sole, and that this debris has similar features to the already deposited drift in upper Taylor valley. This implies that recent past climatic changes have had little effect on the entrainment, transportation and deposition of debris from Taylor Glacier.