Oil in glacial till as drivers of ice streaming and surging

The driving mechanisms of glacier fast flow and the cyclical instability inherent in ice streams and surging glaciers are not fully understood, with current theories of sliding and basal deformation being insufficient in explaining glacier dynamics. Previous work on soil water repellency and interfacial physics shows that the incorporation of a lubricating oil into a sediment enhances the water repellent and water shedding properties. This can form a Slippery Liquid-Infused Porous Surface (SLIPS), whereby a liquid-liquid interface is created when the sediment is exposed to water resulting in extreme water shedding.

In Alberta, Canada, oil sands material has been detected in surficial sediment and in glacial sediments south of the Alberta Oil Sands deposits. It has been hypothesised that this material was eroded and transported subglacially during the Laurentide Glaciation. Here, sediments from the Central Alberta Ice Stream flow track in the former Laurentide Ice Sheet were analysed and compared to samples of the Alberta Oil Sands from mines and natural exposures using oil-oil correlation by gas chromatography-mass spectrometry. The results show evidence of Alberta Oil Sands throughout the Central Alberta Ice Stream flow track, in particular at the terminating margins to the east of Calgary and in the Cooking Lake area to the southeast of Edmonton. These results indicate glacial erosion and long-distance mobilisation of oil sands deposits from Northern Alberta. Three scenarios of SLIPS at the ice-bed interface caused by the presence of a lubricating oil at the bed can be assumed from these results; (i) an oil-wet macroscale SLIPS, (ii) a water-wet macroscale SLIPS, and (iii) a microscale SLIPS.  These SLIPS mechanisms would influence the degree of ice-bed coupling and therefore the proportion and rates of sliding and basal deformation. By understanding the physics occurring at the ice-bed interface it is possible to better predict glacier flow conditions. It is therefore critical that properties affecting wettability and water shedding of sediments such as the presence of an oil are considered in our understanding of transient flow conditions.