Sand-water flows on cold-climate eolian dunes: Environmental analogs for the eolian rock record and martian sand dunes

摘要

Sand-water flows were observed on the slopes of cold-climate eolian dunes in southwestern Saskatchewan, Canada, during episodes of intense thawing in the winters of 2004 and 2005. Meltwater produced flows with varying grain-water contents on slopes of active blowout hollows and parabolic dunes. The sand-water flows emplaced small, structureless, lobate- and tongue-shaped deposits and alluvial fans. The greatest concentration of deposits occurred on south-facing slopes, which frequently thaw in winter from intense insolation. Transport modes ranged from high-density, viscous slurry flows to low-density, hyperconcentrated flows. The triggering cause of these flows is high pore-water pressure that develops in thawed near-surface sand due to impeded infiltration by frozen sand with pore ice at depth. These observations broaden the environmental context of sand-water flows on dunes and contribute to interpretations of these deposits in the eolian rock record and to recent alluvial features observed on Martian sand dunes.