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Scott Polar Research Institute, University of Cambridge, Cambridge CB2 1ER, UK
Icebergs transport debris from ice masses into the glacimarine environment, but iceberg production, debris content and sedimentation rate will vary with glacier dynamics and the nature of marine waters. A model incorporating glaciological and oceanographic parameters calculates the flux of debris calved in icebergs, iceberg melt rates and sedimentation rates with distance from calving tidewater ice fronts. The flux of basal debris calved through a 1 m width of tidewater margin is (hd c/100) vc, where hd and c are basal debris-rich ice thickness and sediment content (%), and vc is iceberg calving rate. Iceberg basal melting for any horizontal interval (dx) away from the calving glacier is dy = (Mb dx)/vb, where Mb is iceberg melt rate and vb is horizontal iceberg velocity. Sediment release for any x increment depends on iceberg debris concentration and previous berg melt history. Model parameters vary with the nature of climatic conditions, on a continuum from cold polar environments (e.g. High Canadian Arctic, Antarctic Peninsula), through sub-polar environments (e.g. Baffin Island, Svalbard) to more temperate environments (e.g. SE Alaska). These parameters include: glacier flow velocity, glacier thermal regime, basal debris-rich ice thickness, and marine water temperature. Model results suggest that iceberg sedimentation rates are lowest for high polar settings, and most rapid in warm maritime and some sub-polar areas. However, icebergs in cold waters transport debris to significantly greater distances from the parent glacier. The model provides calculations of order of magnitude rates of iceberg sedimentation in varying glacimarine settings.
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