Recent Summer Climate Recorded in Complex Varved Sediments, Nicolay Lake, Cornwall Island, Nunavut, Canada |
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| Authors: | Gregory W Hambley Scott F Lamoureux |
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| Institution: | (1) Department of Geography, Queen’s University, Kingston, ON, K7L 3N6, Canada |
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| Abstract: | The recent (1950–1996) varve record from the proximal sediments in Nicolay Lake, Cornwall Island, Nunavut, Canada (77°46′ N,
94°40′ W) contains distinct subannual rhythmites. Deposition of these subannual rhythmites is due primarily to nival snow
melt, with additional sedimentary units resulting from major summer precipitation and subaqueous mass wasting events. In order
to evaluate the potential hydroclimatic signal contained in the varves from the unglacierized catchment, the nival deposition
record was estimated by delineating the initial subannual rhythmite within each varve. When the record is split into temporal
segments based on two phases that exhibit different sediment deposition patterns in the lake, the nival rhythmites are significantly
correlated to annual cumulative melting degree days (MDD) from the nearest weather station Isachsen (78°47′ N, 103°32′ W)
(1950–1962 AD and 1963–1977 AD with r = 0.55 and r = 0.82, respectively). A similar analysis with data from Resolute (74°43′ N,
94°59′ W) yields slightly weaker correlations (1950–1962 AD, r = 0.60; 1963–1994, r = 0.59). The strong positive correlation
with both the Isachsen and Resolute thermal records suggests that the paleoclimatic signal in the sediments reflects regional
climate conditions. Notably, the signal is strongest when the entire melt season is considered; weaker correlations with instrumental
weather records are associated with comparisons limited to the peak melt or early season melt periods. We attribute this to
the ongoing supply of snowmelt through the season in this polar region and the availability of sediment for transport throughout
the melt season. These results indicate that a high resolution hydroclimatic signal is present in the sediments from Nicolay
Lake and can be used for paleoclimate reconstruction provided sedimentary depositional controls are taken into account. |
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| Keywords: | Arctic Canada Lake sediment Paleoclimate Sedimentology Snowmelt Varves |
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