Inflow and lake controls on short-term mass accumulation and sedimentary particle size in a High Arctic lake: implications for interpreting varved lacustrine sedimentary records

Abstract

Sedimentary processes were monitored in a varved lake in the Canadian High Arctic through three melt seasons and revealed that seasonal sediment deposition rates were highly dependent on short-lived inflow events driven by high suspended sediment concentrations that varied with runoff intensity. Our results illustrate that in accordance with the suspended sediment discharge into the lake, the rate of sediment accumulation changed over short distances down-lake, in a given year. This result indicates that there is a rate and accumulation dependence on short-lived, intense inflow conditions. In addition, there was strong evidence for substantial decoupling between deposition rate and mean grain size of sedimentary deposits. These results have important implications for paleoclimate interpretation of annually laminated sedimentary records from dynamic lake environments and suggest that grain size measures may not be representative proxies of inflow competence. Grain size indices based on a measure of the coarser fraction, rather than the bulk sediment, may be more appropriate to use as a link between contemporary runoff processes and sedimentary characteristics.