Groundwater discharge and gully formation on martian slopes

Goldspiel, Jules M.; Squyres, S. W.

doi:10.1016/j.icarus.2010.10.008

Cited by 33 publications

(21 citation statements)

References 59 publications

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“…In our experiments we used a relative stable flow rate (c. 11 ml s −1 ), which is many times smaller than flow rates estimated for Martian gullies (Heldmann et al 2005;Mangold et al 2010;Parsons & Nimmo 2010;Goldspiel & Squyres 2011;Jouannic et al 2012). Comparison between our work and previous experiments has highlighted the importance of the flow rate in the physics of sediment transport and resulting morphology .…”

Section: Implication For Martian Landscape Studiesmentioning

confidence: 93%

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: Implication For Martian Landscape Studiesmentioning

confidence: 93%

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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“…Aquifers as shallow as ∼100 m below the surface might exist on Mars (Goldspiel and Squyres 2011). Possible combinations of the typical geothermal heat flux with a thick, lowconductivity and sufficiently permeable regolith, result in the melting of ice this shallow, allowing the formation of aquifers (Mellon and Phillips 2001).…”

Section: Groundwatermentioning

confidence: 99%

“…The presence of salts in the soil would relax the necessary conditions for the formation of groundwater (Goldspiel and Squyres 2011), allowing underground reservoirs of salty groundwater to form in larger portions of the planet.…”

Section: Groundwatermentioning

confidence: 99%

“…Reprinted with permission from AAAS Heldmann et al (2007) provide a comprehensive review of the strengths and weaknesses of each mechanism proposed to explain the formation of gullies. They suggest that groundwater seepage from deep aquifers is the most likely explanation (Goldspiel and Squyres 2011).…”

Section: Gulliesmentioning

confidence: 99%

“…On the other hand, liquid brines can be present where a source of water exists (e.g., near-surface ground ice) because salts depress the freezing temperature below the present day temperatures at the surface of Mars (Farmer 1976;Clark 1978;Brass 1980;Clark and Van Hart 1981;Moore and Bullock 1999;Bryson et al 2008;Haberle et al 2001;Rao et al 2005;Chevrier and Altheide 2008;Rennó et al 2009b). In addition, monolayers of unfrozen water, referred to as undercooled liquid interfacial (ULI) water, can be present at the surface and in the shallow subsurface (≤1 m) (Möhlmann 2004), and groundwater can be present in the deep subsurface (≥100 m) (Goldspiel and Squyres 2011).…”

Section: Introductionmentioning

confidence: 99%

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Water and Brines on Mars: Current Evidence and Implications for MSL

2013

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Liquid water is a basic ingredient for life as we know it. Therefore, in order to understand the habitability of other planets we must first understand the behavior of water on them. Mars is the most Earth-like planet in the solar system and it has large reservoirs of H 2 O. Here, we review the current evidence for pure liquid water and brines on Mars, and discuss their implications for future and current missions such as the Mars Science Laboratory.Neither liquid water nor liquid brines are currently stable on the surface of Mars, but they could be present temporarily in a few areas of the planet. Pure liquid water is unlikely to be present, even temporarily, on the surface of Mars because evaporation into the extremely dry atmosphere would inhibit the formation of the liquid phase, where the temperature and pressure are high enough so that water would neither freeze nor boil. The exception to this is that monolayers of liquid water, referred to as undercooled liquid interfacial water, could exist on most of the Martian surface. In a few places liquid brines could exist temporarily on the surface because they could form at cryogenic temperatures, near ice or frost deposits where sublimation could be inhibited by the presence of nearly saturated air.Both liquid water and liquid brines might exist in the shallow subsurface because even a thin layer of soil forms an effective barrier against sublimation allowing pure liquid water to form sporadically in a few places, or liquid brines to form over longer periods of time in large portions of the planet. At greater depths, ice deposits could melt where the soil conductivity is low enough to blanket the deeper subsurface effectively. This could cause the formation of aquifers if the deeper soil is sufficiently permeable and an impermeable layer exists below the source of water.The fact that liquid brines and groundwater are likely to exist on Mars has important implications for geochemistry, glaciology, mineralogy, weathering and the habitability of Mars.

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Assessing hydrodynamic effects on jarosite dissolution rates, reaction products, and preservation on Mars

et al. 2015

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Jarosite flow-through dissolution experiments were conducted in ultrapure water (UPW), pH 2 sulfuric acid, and saturated NaCl and CaCl 2 brines at 295-298 K to investigate how hydrologic variables may affect jarosite preservation and reaction products on Mars. K + -based dissolution rates in flowing UPW did not vary significantly with flow rate, indicating that mineral surface reactions control dissolution rates over the range of flow rates investigated. In all of the solutions tested, hydrologic variables do not significantly affect extent of jarosite alteration; therefore, jarosite is equally likely to be preserved in flowing or stagnant waters on Mars. However, increasing flow rate did affect the mineralogy and accumulation of secondary reaction products. Iron release rates in dilute solutions increased as the flow rate increased, likely due to nanoscale iron (hydr)oxide transport in flowing water. Anhydrite formed in CaCl 2 brine flow-through experiments despite low temperatures, while metastable gypsum and bassanite were observed in batch experiments. Therefore, observations of the hydration state of calcium sulfate minerals on Mars may provide clues to unravel past salinity and hydrologic conditions as well as temperatures and vapor pressures.

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Groundwater discharge and gully formation on martian slopes

Cited by 33 publications

References 59 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

Water and Brines on Mars: Current Evidence and Implications for MSL

Assessing hydrodynamic effects on jarosite dissolution rates, reaction products, and preservation on Mars

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