Martian gully activity and the gully sediment transport system

Dundas, C. M.; Conway, Susan J.; Cushing, G. E.

doi:10.1016/j.icarus.2022.115133

Cited by 7 publications

(11 citation statements)

References 66 publications

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“…Despite these observations, it remains debated what the original formation process of these landforms is. Our experimental results support the hypothesis by Diniega et al (2010) and Dundas et al (2012Dundas et al ( , 2015Dundas et al ( , 2019Dundas et al ( , 2022) that current activity, by granular flow processes driven by CO 2 sublimation, are actively forming Martian gullies, and are not merely modifying older water-formed features, as suggested by Dickson et al (2023).…”

Section: Implications For Martian Landscape Evolution and Granular Fl...supporting

confidence: 89%

“…The gas flux created can potentially destabilize large amounts of slope material, also underneath the ice (Pilorget & Forget, 2016). However, the requirement of slab ice means that the latter mechanism is only applicable to Martian gullies at latitudes >40°S where evidence for slab ice is observed (Dundas et al, 2017(Dundas et al, , 2019, whereas half of the observed active gully sites on the southern hemisphere are present at latitudes <40°S (Dundas et al, 2022). Furthermore, this hypothesis does not explain how the pressurized flows underneath a layer of CO 2 ice would result in the deposition of new lobate deposits and the movement of meterscale boulders.…”

Section: Introductionmentioning

confidence: 99%

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The Dynamics of CO₂‐Driven Granular Flows in Gullies on Mars

Roelofs,

Conway,

van Dam

et al. 2024

JGR Planets

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Martian gullies are landforms consisting of an erosional alcove, a channel, and a depositional apron. A significant proportion of Martian gullies at the mid‐latitudes is active today. The seasonal sublimation of CO2 ice has been suggested as a driver behind present‐day gully activity. However, due to a lack of in situ observations, the actual processes causing the observed changes remain unresolved. Here, we present results from flume experiments in environmental chambers in which we created CO2‐driven granular flows under Martian atmospheric conditions. Our experiments show that under Martian atmospheric pressure, large amounts of granular material can be fluidized by the sublimation of small quantities of CO2 ice in the granular mixture (only 0.5% of the volume fraction of the flow) under slope angles as low as 10°. Dimensionless scaling of the CO2‐driven granular flows shows that they are dynamically similar to terrestrial two‐phase granular flows, that is, debris flows and pyroclastic flows. The similarity in flow dynamics explains the similarity in deposit morphology with levees and lobes, supporting the hypothesis that CO2‐driven granular flows on Mars are not merely modifying older landforms, but they are actively forming them. This has far‐reaching implications for the processes thought to have formed these gullies over time. For other planetary bodies in our solar system, our experimental results suggest that the existence of gully like landforms is not necessarily evidence for flowing liquids but that they could also be formed or modified by sublimation‐driven flow processes.

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Section: Implications For Martian Landscape Evolution and Granular Fl...supporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

The Dynamics of CO₂‐Driven Granular Flows in Gullies on Mars

Roelofs,

Conway,

van Dam

et al. 2024

JGR Planets

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“…(2015) are represented by the black dots, and the active gullies sites reported in Dundas et al. (2022) by the gray diamonds. No MOLA background has been added to the plot.…”

Section: Discussion and Perspectivesmentioning

confidence: 99%

“…Observed active gullies reported by Dundas et al. (2022) are represented by gray diamonds. The PCM outputs are retrieved at 2 p.m., that is, the local time when most CRISM/OMEGA data were acquired.…”

Section: Validations Of the Implementationmentioning

confidence: 97%

“…Smith et al, 1999) at https://pds-atmospheres.nmsu.edu. Frost detections are from , Vincendon (2015) Gullies site reported in the last Figure can be obtained from Dundas, McEwen et al (2019), Dundas et al (2022), and Harrison et al (2015). Data files for figures used in this analysis are available in a public repository, see Lange, Forget, Dupont, et al (2023).…”

Section: Data Availability Statementmentioning

confidence: 99%

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Modeling Slope Microclimates in the Mars Planetary Climate Model

Lange,

Forget,

Dupont

et al. 2023

JGR Planets

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A large number of surface features (e.g., frost, gullies, slope streaks, recurring slope lineae) are observed on Martian slopes. Their activity is often associated with the specific microclimates on these slopes, which have been mostly studied with one‐dimensional radiative balance models to date. We develop here a parameterization to simulate these microclimates in 3D Global Climate Models. We first demonstrate that any Martian slope can be thermally represented by a poleward or equatorward slope, that is, the daily average, minimum, and maximum surface temperatures depend on the North‐South component of the slope. Based on this observation, we implement here a subgrid‐scale parameterization to represent slope microclimates (radiative fluxes, volatile condensation, ignoring slope winds for now) in the Mars Planetary Climate Model and validate it through comparisons with surface temperature measurements and frost detections on sloped terrains. With this new model, we show that slope microclimates do not have a significant impact on the seasonal CO2 and H2O cycles on a global scale. Furthermore, short‐scale slopes (i.e., less than ∼1 km in length) do not significantly impact the thermal state of the atmosphere. Ninety‐one percent of the active gullies are found where our model predicts CO2 frost, suggesting that their activity is related to processes involving CO2 ice. However, the low thicknesses (≤tens of cm) predicted at mid‐latitudes rule out mechanisms involving large amounts (∼meters) of ice. This model opens the way to new studies on surface‐atmosphere interactions in present and past climates.

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