Retrogressive thaw slumps on Mars: constraints on potential formation mechanisms.

Wan Bun Tseung Jean-Michel (1) and Brian J. Moorman (2)

(1) Department of Geography, ES356, 2500 University Drive N.W., University of Calgary, Calgary, Alberta, Canada, T2N4C2, (jm.wanbt@ucalgary.ca)

(2) Department of Geography, ES356, 2500 University Drive N.W., University of Calgary, Calgary, Alberta, Canada, T2N4C2, (moorman@ucalgary.ca).

In permafrost environments of Earth, ground-ice features are diverse and represent the result of multiple processes that currently operate or have modified large parts of the Arctic. In such environments, retrogressive thaw slumps (RTS) are common and form when the thermal regime of ice-rich ground changes and when ground-ice is exposed to atmospheric conditions. Subsequently, collapse of surficial material occurs as the ice wall retreats. The cryotic state of Mars suggests a greater role of H2O ground-ice compared to Earth’s crust, which is mostly thawed. While various ground-ice features such as pingos, ice-wedge polygons and thermokarst have been observed on Mars, the presence of RTSs has not been reported yet. An analysis of the thermophysical interactions between the atmosphere and the near subsurface indicates that under current conditions on Mars, the melting of ground-ice is not likely to occur and RTS formation should be non-existent, unless driven by sublimation. Based on mini-TES data returned by the Mars Exploration Rovers and using a heat conduction model, near subsurface temperatures were derived. Results indicate that while surface temperatures can reach up to about 30°C, subsurface temperatures above 0°C can only penetrate the upper few centimeters of the ground and quickly decrease well below the freezing point of water. Additionally, since this upper layer is likely desiccated any ground-ice melt probably does not occur. These results therefore suggest that under current conditions, ground-ice deeper than a few decimeters should stay stable unless exposed to atmospheric conditions.

Corresponding Author: Jean-Michel Wan Bun Tseung