Lacustrine Sedimentary Environments in High Arctic Proglacial Bear Lake, Devon Island, Nunavut
Scott F. Lamoureux, Robert Gilbert, and Ted Lewis*
Department of Geography, Queen's University, Kingston, Ontario, K7L 3N6 Canada
lamoureux@lake.geog.queensu.ca
(*present address, Climate System Research Center, Department of Geosciences,
University of Massachusetts, Amherst, Massachusetts 01003 U.S.A.)
October 30, 2001
Abstract
Combined catchment, subbottom acoustic, and sedimentary studies of High Arctic, proglacial Bear Lake, Devon Island,
were carried out to evaluate the role lacustrine processes and Holocene catchment evolution have had on the
sedimentary record. In the proximal basin, bottom deposits up to 60 m thick are generated in part by turbid
underflows associated with peak meltwater flow from the Devon Island Ice Cap. These underflows produce
rhythmically laminated structures that are likely varves. In shallower locations, accumulation is slower and
results from homopycnal distribution of fine suspended sediment throughout the proximal basin, resulting in a
simple varve couplet. The distal basin is isolated from glacial meltwater by a shallow sill, although some
fine-grained detrital carbonate transported by the glacial meltwater is deposited in both basins. In most
locations in the distal basin Holocene sediments are less than 10 m thick. They are composed primarily of massive
clay and some carbonate interrupted by irregular graded carbonate units produced by sporadic heavy summer rainfall
and sediment transport from small plateau tributaries. Eolian sedimentation is also important throughout the lake,
especially when high accumulations melt through the ice in the proximal basin, producing isolated grains and layers
of coarse sand in the sedimentary record. Holocene ice margin changes have influenced the sedimentary record
substantially, particularly during the mid-Holocene when the ice cap is inferred to have retreated from the catchment.