| Summary: | Abstract: Linnévatnet is a High Arctic glacier-fed lake in Svalbard in which past climatic characteristics are recorded in laminated lake sediments that likely span the past 9,000 years. The laminae are comprised of annual terrigenous couplets consisting of distinct coarse summer and fine winter layers. Previous studies in similar proglacial lakes throughout the Arctic and alpine regions have determined that varves of this type may record an archive of past weather and climatic influences in the catchment area. Sedimentation in Linnévatnet has been studied since 2003 using sediment traps and instruments deployed yearly and seasonally. The traps were deployed at five locations in the lake proximal and distal to the major inlet. Depending on the water depth at each location two to five traps were attached mooring lines. In the sediment traps, the summer melt season sediment is represented by distinct coarse sediment events reflecting meltwater pulses, the timing of which are constrained by time lapse photography and loggers on the moorings. The first and coarsest (26 microns) grained sediment pulse was deposited on July 4 5,2008, coinciding with peak snowmelt discharge. Subsequent events appear as finer (12 14 microns) graded laminae in the traps and are associated with similar high discharge events in mid-July. The fine winter layer (5 8 microns) coarsens slightly upward and reflects quiet winter sedimentation. Sediment stratigraphy and grain size trends in 2007 2008 were compiled with sediment trap analyses back to 2003 to form a composite record to compare with lake bottom deposition as reflected in sediment cores recovered adjacent to the moorings. Thin sections of laminated sediments from the cores display complex summer layer stratigraphy with multiple sedimentation units as seen in the sediment traps. Correlation between distinct units in the thin sections and sediment traps was attempted to evaluate climatic and environmental conditions responsible deposition of recent varved sediments.
|
|---|