EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Experimental CO2-driven granular flows under Martian atmospheric conditions 

Lonneke Roelofs1, Susan Conway2, Matthew Sylvest3, Manish Patel3, Jim McElwaine4, Maarten Kleinhans1, and Tjalling de Haas1
Lonneke Roelofs et al.
  • 1Utrecht University, Physical Geography, Utrecht, Netherlands (
  • 2Université de Nantes, Laboratoire De Planétologie Et Géodynamique, Nantes, France
  • 3Open University, Milton Keynes, United Kingdom
  • 4Durham University, Department of Earth Sciences, Durham, United Kingdom

Martian gullies are alcove-channel-fan systems that have been hypothesized to be formed by the action of liquid water and brines, the effects of sublimating CO2 ice, or a combination of these processes. Recent activity and new flow deposits in these systems have shifted the leading hypothesis from water-based flows to CO2-driven flows, as it is hard to reconcile present activity with the low availability of atmospheric water under present Martian conditions. Direct observations of flows driven by metastable CO2 on the surface of Mars are however nonexistent, and our knowledge of CO2-driven flows under Martian conditions remains limited. For the first time, we produced CO2-driven granular flows in a small-scale flume under Martian atmospheric conditions in the Mars Chamber at the Open University (UK). The experiments were used to quantify the slope threshold and CO2 fraction limits for fluidization. With these experiments, we show that the sublimation of CO2 can fluidize sediment and sustain granular flows under Martian atmospheric conditions, and even transport sediment with grain sizes equal to half the flow depth. The morphology of the deposits is lobate and depends highly on the CO2-sediment ratio, sediment grain size, and flume angle. The gas-driven granular flows are sustained under low (<20º) flume angles and small volumes of CO2 (around 5% of the entire flow). Pilot experiments with sediment flowing over a layer of CO2 suggest that even smaller percentages of CO2 ice are needed for fluidization. The data further shows that the flow dynamics are complex with surging behavior and complex pressure distribution in the flow, through time and space.

How to cite: Roelofs, L., Conway, S., Sylvest, M., Patel, M., McElwaine, J., Kleinhans, M., and de Haas, T.: Experimental CO2-driven granular flows under Martian atmospheric conditions , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-679,, 2022.


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