Seasonal activity and morphological changes in martian gullies

Dundas, C. M.; Diniega, S.; Hansen, C. J.; Byrne, Shane; McEwen, A. S.

doi:10.1016/j.icarus.2012.04.005

Cited by 203 publications

(193 citation statements)

References 65 publications

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“…1a, b; e.g. Malin & Edgett 2000;2006;Balme et al 2006;Dickson et al 2007;Dundas et al 2010Dundas et al , 2012Dundas et al , 2015Dundas et al , 2018Harrison et al 2015;Raack et al 2015;Conway et al 2015Conway et al , 2018; (2) 'dune gullies' ( Fig. 1c; e.g.…”

Section: Stability Of Liquid Water At the Surface Of Marsmentioning

confidence: 99%

“…1; e.g. Malin & Edgett 2000;Costard et al 2002;Mangold et al 2003;Reiss & Jaumann 2003;Védie et al 2008;Diniega et al 2010Diniega et al , 2013Dundas et al 2010Dundas et al , 2012Dundas et al , 2015Reiss et al 2010;Jouannic et al 2015; this volume, in review; Raack et al 2015;Pasquon et al 2016;this volume, in review). The physical processes involved in the formation of gullies and their present-day activity have not been unambiguously identified and are still under debate.…”

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confidence: 99%

“…Ingersoll 1970;Haberle et al 2001;Hecht 2002;Richardson & Mischna 2005;Sears & Moore 2005); (2) ongoing activity is recorded at locations and at times of year when the temperature is below the melting point of water (e.g. Diniega et al 2010;Dundas et al 2012;Raack et al 2015;Pasquon et al this volume, in review); (3) volumetrically limited water sources (atmospheric humidity and/or perched topographic aquifers) cannot explain the large numbers of observed features (e.g. Balme et al 2006;Kneissl et al 2010;Harrison et al 2015) or the physical extent of the landforms observed (e.g.…”

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confidence: 99%

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Downslope sediment transport by boiling liquid water under Mars-like conditions: experiments and potential implications for Martian gullies

Herny

Conway

Raack

et al. 2018

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Gullies are widespread morphological features on Mars for which current changes have been observed. Liquid water has been one of the potential mechanisms to explain their formation and activity. However, under present-day Martian conditions, liquid water is unstable and should only be transiently present in small amounts at the surface. Yet little attention has been paid to the mechanisms by which unstable water transports sediment under low atmospheric pressure. Here we present the results of laboratory experiments studying the interaction between liquid water flowing over a sand bed under Mars-like atmospheric pressure (c. 9 mbar). The experiments were performed in a Mars Simulation Chamber (at the Open University, UK), in which we placed a test bed of fine sand at a 25°slope. We chose to investigate the influence of two parameters: the temperature of the water and the temperature of the sand. We performed 27 experiments with nine different combinations of water and sand temperatures ranging from 278 to 297 K. Under all experimental conditions, the water was boiling. We investigated and compared the types and timing of sediment transport events, and the shapes, characteristics and volumes of the resulting morphologies. In agreement with previous laboratory studies we found that more intense boiling increased the volume of sediment transported for a given volume of water. We found four main types of sediment transport: entrainment by overland flow; grain ejection; grain avalanches; and levitation of saturated sand pellets. Our results showed that increasing sand temperature was the main driving parameter in increasing the sand transport and in modifying the dominant sediment transport mechanism. The temperature of the water played a negligible or minor role, apart from the duration of sand ejection and avalanches, which lasted longer at low water temperature. At low sand temperature the majority of the sand was transported by overland flow of the liquid water. At higher sand temperatures the transport was dominated by processes triggered by the boiling behaviour of the water. At the highest temperatures, sediment transport was dominated by the formation of levitating pellets, dry avalanches and ejection of the sand grains. This resulted in a transport volume about nine times greater at a sand temperature of 297 K compared with 278 K. Our heat transfer scaling shows that the boiling behaviour will be enhanced under Martian low gravity, resulting in more efficient transport of sediment by levitating sand pellets even at temperatures close to the triple point. Our results showed that the boiling intensity played an important role in the physics of sediment transport by liquid water. This implied that the amount of water required to produce morphological changes at the surface of Mars could be lower than previously estimated by assuming stable liquid water. Boiling is a critical process to be considered when assessing gully formation and modification mechanisms mobilized by liquid water. Our work could ha...

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Section: Stability Of Liquid Water At the Surface Of Marsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Downslope sediment transport by boiling liquid water under Mars-like conditions: experiments and potential implications for Martian gullies

Herny

Conway

Raack

et al. 2018

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“…1), Martian gullies were reasoned to have been formed by flowing water (Malin & Edgett 2000). With the observation of active modification and extension of gullies (Dundas et al 2012), the apparent lack of liquid water under current Martian surface conditions leads to increased interest in alternative formative mechanisms. CO 2 is abundant on Mars, both as a gas (accounting for c. 95% of the atmosphere; Bargery et al 2011) and as solid ice at the surface.…”

mentioning

confidence: 99%

“…Recent studies suggest that seasonal freezing and sublimation of CO 2 ice could be responsible for present-day gully activity on Mars (Diniega et alassociate the timing of morphological changes with the seasonal CO 2 cycle (Reiss & Jaumann 2003;Dundas et al 2010Dundas et al , 2012Dundas et al , 2014Reiss et al 2010;McEwen et al 2011;Raack et al 2015;Vincendon 2015;Pasquon et al 2016) while experimental simulations (Diniega et al 2013;Sylvest et al 2016;McKeown et al 2017) and numerical simulations (Cedillo-Flores et al 2011;Pilorget & Forget 2016) demonstrate the efficacy of CO 2 slope mobilization models.…”

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confidence: 99%

CO ₂ sublimation in Martian gullies: laboratory experiments at varied slope angle and regolith grain sizes

Sylvest

Dixon

Conway

et al. 2018

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Martian gullies were initially hypothesized to be carved by liquid water, due to their resemblance to gullies on Earth. Recent observations have highlighted significant sediment transport events occurring in Martian gullies at times and places where CO 2 ice should be actively sublimating. Here we explore the role of CO 2 sublimation in mobilizing sediment through laboratory simulation. In our previous experimental work, we reported the first observations of sediment slope movement triggered by the sublimation of CO 2 frost. We used a Mars regolith simulant near the angle of repose. The current study extends our previous work by including two additional substrates, fine and coarse sand, and by testing slope angles down to 10°. We find that the Mars regolith simulant is active down to 17°, the fine sand is active only near the angle of repose and the coarse sand shows negligible movement. Using an analytical model, we show that under Martian gravity motion should be possible at even lower slope angles. We conclude that these mass-wasting processes could be involved in shaping Martian gullies at the present day and intriguingly the newly reported CO 2 -creep process could provide an alternative explanation for putative solifluction lobes on Mars.

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Identification of Mars gully activity types associated with ice composition

Vincendon

2015

J. Geophys. Res. Planets

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• We characterize the presence and composition of ice at currently active gullies.• Major channel incisions systematically occur where CO 2 ice is observed or probable.• Some activity (e.g. bright deposits) is not associated with CO 2 but with H 2 O ice. AbstractThe detection of geologically recent channels at the end of the twentieth century rapidly suggested that liquid water could have been present on Mars up to recent times. A mechanism involving melting of water ice during ice ages in the last several million years progressively emerged during years following the first observations of these gullies. However, the recent discovery of current activity within gullies now suggests a paradigm shift where a contemporary CO 2 ice-based and liquid water-free mechanism may form all gullies. Here we perform a survey of near-infrared observations and construct time sequences of water and CO 2 ice formation and sublimation at active gully sites. We observe that all major new erosive features such as channel development or lengthening systematically occur where and, if applicable, when CO 2 ice is observed or probable. CO 2 ice layers are however estimated to be only 1 mm to 1 cm thick for low-latitude sites, which may have implication for potential formation mechanisms. We also observe that part of current gully activity, notably the formation of some new deposits, is poorly compatible with the presence of CO 2 ice. In particular, all new bright deposits reported in the literature have a low CO 2 ice probability while water ice should be present at most sites. Our results confirm that CO 2 ice is a key factor controlling present-day channel development on Mars and show that other mechanisms, potentially involving sublimation or melting of water ice, are also contributing to current gully activity.

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Seasonal activity and morphological changes in martian gullies

Cited by 203 publications

References 65 publications

Downslope sediment transport by boiling liquid water under Mars-like conditions: experiments and potential implications for Martian gullies

Downslope sediment transport by boiling liquid water under Mars-like conditions: experiments and potential implications for Martian gullies

CO ₂ sublimation in Martian gullies: laboratory experiments at varied slope angle and regolith grain sizes

Identification of Mars gully activity types associated with ice composition

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Seasonal activity and morphological changes in martian gullies

Cited by 203 publications

References 65 publications

Downslope sediment transport by boiling liquid water under Mars-like conditions: experiments and potential implications for Martian gullies

Downslope sediment transport by boiling liquid water under Mars-like conditions: experiments and potential implications for Martian gullies

CO 2 sublimation in Martian gullies: laboratory experiments at varied slope angle and regolith grain sizes

Identification of Mars gully activity types associated with ice composition

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CO ₂ sublimation in Martian gullies: laboratory experiments at varied slope angle and regolith grain sizes