| Summary: | Abstract: Over the last ca. 15 years, the southeastern portion of Kongsvegen glacier has retreated back onto land and an ice-marginal delta has formed at its terminus. The delta has an annual growth rate of 6.0x105 m3 a-1, determined from bathymetric profiling and aerial photos taken inbound and outbound of Ny Ålesund. Sedimentation in Kongsfjorden, where the subglacial derived meltwater stream discharges after flowing over the delta, were recorded, from sediment traps located at the given distances, as 7.5 ± 1.6 g cm-2 a-1 (69.4 mm a-1 vertical thickness) at 204m in fjord from the source, and 9.19 ± 4.4 g cm-2 a-1 (85.5 mm a-1) at 1193 m from the delta source. The higher value with distal location being attributed to the influx of sediment from a submarine, subglacial meltwater discharge plume from Kronebreen glacier ~2.5 km north of the newly formed delta (Trusel et al., 2006). Sedimentary processes, observed in CTD (conductivity, temperature, depth) profiles, strongly resemble those characteristics of Alaskan glaciers in the temperate environment, including settling sediment layers, interflows, and turbidity flows. These structures are also recorded in both gravity and box cores by sedimentary core logging, magnetic susceptibility, core x-rays, and mineralogical and sediment size distribution histogram differences. Erosive efficiency and transportation of sediment of Svalbard’s polythermal glaciers, in the subpolar environment, are intermediately between Alaskan warm-based, temperate environment, and Antarctic cold-based, polar environment, glaciers. The sedimentation rate of glaciers in Svalbard is one order of magnitude above Antarctic glaciers, and one order of magnitude below Alaskan tidewater glaciers. See also Trusel, L.D., Powell, R.D., Cumpston, R.M., and Brigham-Grette, J., 2010, Modern glacimarine processes and potential future behaviour of Kronebreen and Kongsvegen polythermal tidewater glaciers, Kongsfjorden, Svalbard: Geological Society, London, Special Publications, v. 344, p. 89–102, doi: 10.1144/SP344.9.
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