Sedimentation processes and patterns in a glacier-fed lake with low sediment input

Hector Lake, situated in the eastern Rocky Mountains of western Alberta, is fed primarily by nival and glacial meltwater. During summer when the lake is thermally stratified, inflowing water and fine sediment enter the lake as overflows and shallow interflows that are transformed into complex, but mostly downlake, epilimnial currents generated by downlake katabatic winds. Coriolis deflections produce a strong right-hand tendency in sedimentation patterns, with resulting crosslake (south-to-north) as well as downlake (west-to-east) proximal–distal trends: reduction in grain size, sedimentation rates, total carbonate, dolomite/(dolomite + calcite) and varve thickness.Laminae in bottom sediments are produced by inflow variations that are largely dependent upon air temperature. Five orders of inflow, and thus sediment input, variation capable of producing laminae are recognized: diurnal, subseasonal (short-term weather changes), seasonal (nival melt vs. glacial melt), annual and exceptional inflow events. Based upon laminae character, four facies of glacier-derived and one of non-glacier-derived bottom sediments are recognized in Hector Lake.