Flux of debris transported by ice at three Alaskan tidewater glaciers

• Published in: Journal of Glaciology
• Main Authors: Hunter, Lewis E., Powell, Ross D., Lawson, Daniel E.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 1996
• Subjects: glacier; glaciers; Journal of Glaciology; Tidewater; Alaska
• Online Access: http://dx.doi.org/10.1017/s0022143000030586; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000030586

Abstract The stability of a tidewater terminus is controlled by glacial dynamics, calving processes and sedimentary processes at the grounding line. An investigation of grounding-line sediment dynamics and morainal-bank sediment budgets in Glacier Bay, Alaska, U.S.A., has yielded data that enable us to determine the debris fluxes of Grand pacific, Margerie and Muir Glaciers. Debris flux ranges from 10 5 to 10 6 m 3 a −1 , one to two orders of magnitude lower than the glacifluvial sediment fluxes (10 6 −10 7 m 3 a −1 ). Combined, these fluxes represent the highest yields known for glacierized basins. Large debris fluxes reflect the combined effects of rapid glacier flow, driven by the maritime climate of southeast Alaska, and highly erodible bedrock. Englacial-debris distribution is affected by valley width and relief, both of which control the availability of sediment. The number of tributaries controls the distribution and volume of debris in englacial and supraglacial moraines. At the terminus, iceberg-rafting removes up to two orders of magnitude more sediment from the ice-proximal environment than is deposited by melt-out or is dumped during calving events. Rough estimates of the sediment flux by deforming beds suggests that soft-bed deformation may deliver up to an order of magnitude more sediment to the terminus than is released from within the glacier ice.