ABSTRACT: Varve formation in a non-glacial High Arctic lake and the interannual and centennial scale variability of snow melt intensity and rain events.

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Abstract

Sawtooth lake, Nunavut Canada, contains a ~2500 years long varved sequence. We have investigated the processes involved in sediment transport to the lake, and examined the physical limnology of the lake to better understand the within-lake sediment transport processes. These investigations provide a mechanistic basis for interpreting the sedimentary record, to complement more empirical statistical calibrations. We synthesize data on the current limnology, and sedimentary processes observed at South Sawtooth Lake. We classify the sedimentary fabrics in the sediments into five main facies, each representing different processes that lead to a particular type of sediment deposition in the lake. We then interpret the overall sedimentary record to be made up of varves. Sediment accumulation is mainly due to spring snowmelt that forms silty laminations grading into clay. Coarser non-erosive sand beds frequently interrupt this regular sedimentation. Field observationand evidences from the analysis of the sediment, mainly from thin-sections, point out that these coarse beds are due to summer rain events. This paper focusses on the investigation of both short (interannual) and long (centennial) scale variability of snowmelt intensity and summer rain events over the last 1000 years.

Bibliography of Canadian Geomorphology