Mass Movement by solifluction and Syngenetic Dynamic of Permafrost in the High Arctic, Ward Hunt Island, Canadian High Arctic

English Abstract:

According to recent climatic scenarios, climates changes will affect the Arctic more than any other region of the planet. The high Arctic, which is essentially bare of vegetation, will have a strong response to climates changes and will be characterized by an acceleration of periglacial processes associated with permafrost thawing. Mass movements on slopes will be favored by the deepening of the active layer increasing the creep and continuous sliding of the material over the ice-rich permafrost table.

Our project focused on the influence of solifluction lobes movements on permafrost dynamics at Ward Hunt Island, Nunavut (Canada). On the island, many solifluction lobes deform and entrain sediments downslope. Considering the recent deepening of the active layer, the increase of material downslope may modify permafrost dynamics, a question that is not currently considered by permafrost model scenarios.

We used 3D laser scanning techniques and total station surveys to reconstruct the microtopography and volume of solifluction lobes. Permafrost coring and ground penetrating radar surveys were used to characterize solifluction lobes cryostratigraphy. Permafrost cores were then analyzed using micro-computed tomography to quantify the different components of permafrost (sediments, ice, organic matter and gas) which were also measured in laboratory.

Our study demonstrated that the movement of solifluction lobes leads to the accumulation of coarse material (gravel) with high hydraulic conductivity on the peripheral ridges of the lobe which strongly modifies slope hydrology. In the center of the lobes, the recurrent and substantial accumulation of finer-grained material downslope modifies permafrost dynamics and promotes the aggradation of ground ice. These findings suggest that the occurrence of these ice-rich zones may contribute to slow down the degradation of permafrost, due to the important effect of latent heat represented by this new volume of ground ice.