Student Research Projects: Kongsfjorden
Research in Kongsfjorden is focused on glacial and glacimarine processes influencing sedimentation in front of tidewater margins. In temperate marine settings, ice-proximal laminae form as tidalites and varves, but laminae can also be due to large rainstorm events. Varve thicknesses vary depending on the magnitude of annual sediment discharges from outwash streams and subglacial plumes. Previous experience has shown that greater than 70% of all glacimarine sediment most commonly originates from such meltwater streams in cool temperate and sub-polar settings. The periodicity of lamina production, however, is poorly understood as are the source causes. In cooler settings, sediment is stratified by the degree of seasonal sea ice that controls the amount of iceberg rafting of sediment, so when sea ice is extensive the sediment is dominated by mud, but when the area is free of sea ice, icebergs raft coarser glacial debris into the area.
Major research themes capture the complexity of sediment transport and deposition processes influencing the marine sediment archive associated with polythermal tidewater glaciers, icebergs, meltwater streams, and marine currents:
- Glacimarine ice-contract delta sedimentation
- Delta front processes
- Subglacial stream and plume processes
- Oceanographic and tidal influences on fjord sedimentation
- Calving processes
- Provenance studies
- Terrestrial subglacial meltwater sources
Past students sampled glacier and iceberg ice for debris concentrations and performed CTD casts at different stages of tide and meltwater discharge cycles to define where the sediment was being transported and deposited.
Water samples were filtered to determine suspended sediment concentrations. Small box-cores and short gravity cores of fjord sediment were collected to identify the sedimentary facies forming on the fjord floor and their relation to observed processes. Bathymetric profiles obtained by using a small sub-bottom profiler and GPS from one of the small boats helped to establish baselines to allow future students to determine the rate of sediment infilling of the fjord by the glaciers. GPS mapping allowed the students to determine the current position of the tidewater cliff as well as its rate of retreat by comparing their GPS measurements to older aerial photographs.
Others have monitored iceberg calving and its rate and sampled them to determine debris sources.
From their observations, the students determined that the glacimarine processes in Kongsfjord are similar in part to those observed in the temperate glacimarine fjords of Alaska, which are known to form tidal rhythmites (cyclopels and cyclopsams) in fjord floor muds. Based on their own sediment flux and mass accumulation data, they determined that Svalbard's polythermal glacial systems lie between those of fully polar and fully temperate glacial regimes, and reflect the efficiency of each regime to erode its bed and transport that debris and sediment to the glacier terminus. They speculated that with additional Arctic warming, the sedimentary processes and deposited lithofacies will become more similar to temperate tidewater glaciers systems and less like those of fully polar regimes.