Rates of sediment deposition in a hypersaline lake in the northern Great Plains,western Canada |
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| Authors: | William M Last |
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| Institution: | (1) Department of Geological Sciences, University of Manitoba, R3T 2N2 Winnipeg, Canada |
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| Abstract: | Remarkably high rates of sedimentation (up to nearly 60 kg m−2 yr−1) are documented for offshore areas of Freefight Lake, a deep, hypersaline, meromictic lake in the northern Great Plains of
Canada. Most material in the offshore sediment traps consists of soluble and suparingly soluble endogenic salts. Deposition
of allogenic sediment is minor. The observed high sedimentation rates are in response to several mechanism: (i) freeseout
precipitation of salts from the mixolimnion; (ii) redistribution of shallow water endogenic precipitates by turbidity flows
and interflow processes; and (iii) precipitation of salts from within the monimolimnion Because the bottom water mass of the
lake is essentially isothermal and isochemical, large scale temperature induced remobilization of these salts at or near the
sediment-water interface is unlikely. Similarly, the morphology of the basin suggests that resuspension of bottom sediment
by waves in the offshore areas of the basin is negligible. Although the sedimentation rates observed in Freefight Lake are
extraordinarily high and considerably greater than other modern lacustrine sedimentation rates documented in the literature
to date, the observed rates are entirely compatible with suggested accumulation rates of ancient evaporite sequences.
Palliser Tringle Global Change Contribution Number 6. |
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| Keywords: | Sedimentation rates deep-water evaporites sediment trap Canada Saskatchewan salt lake sedimentology |
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