Publication Date:
2016-08-10
Description:
High Arctic lakes are commonly used for paleoclimatic reconstructions because they are particularly sensitive to climate variability. However, the processes leading to sediment deposition and distribution in these lakes are often poorly understood. Here, for the first time in the Canadian High Arctic, we present original data resulting from swath bathymetry and sub-bottom surveys carried out on two lakes at Cape Bounty, Melville Island. The results reveal the dynamic nature of the lakes, in which mass movements deposits and bedforms on the deltas reflect frequent slope instabilities and hyperpycnal flow activity. The analysis of the mass movement deposits reveals that small blocky debris flows/avalanches, debris flows and a slide occurred during the Holocene. These mass movements are believed to have been triggered by earthquakes and potentially by permafrost thawing along the shoreline. Altogether, these mass movement deposits cover more than 30% of the lake floors. Additionally, the river deltas on both lakes were mapped and reveal the presence of several gullies and bedforms. The presence of gullies along the delta front indicates that hyperpycnal flows generated at the river mouth can transport sediment in different trajectories downslope, resulting in a different sediment accumulation pattern and record. The dynamic nature of these two lakes suggests that further analysis on sediment transport and distribution within Arctic lakes is required in order to improve paleoclimatic reconstructions.
Print ISSN:
0148-0227
Topics:
Geosciences
,
Physics
