Morphological evolution of a well-constrained, subaerial–subaqueous source to sink system: Wabush lake

Abstract

Since 1964, the Iron Ore Company of Canada has deposited iron tailings resulting from mining operations into Wabush Lake, Western Labrador, Canada. This activity has resulted in a continuous hyperpycnal flow flowing over the lake floor. Bathymetric surveys were carried out between 1999 and 2008 as part of the overall environmental Iron Ore Company of Canada plans to maintain safe disposal strategies of tailings into the lake. Here, this dataset is used to study the evolution of different channels present in Wabush Lake and their link with knickpoints found at the head of most of these channels. The channels show notable evolution from one survey to the next. Some knickpoints and channels may be followed throughout more than one sur-vey; the evolution of these knickpoints is the process responsible for the cre-ation of erosional channels. The context in which they appear, as well as the evolution of some of the subaqueous channels is analysed. Cyclic steps and sediment waves are also found in the lake. These rhythmic bedforms, also created by the passage of turbidity currents, are analysed. Sediment waves found in Wabush Lake show values for both wavelength and wave height that are approximately one order of magnitude smaller than most of those found in the marine environment.