Martian subsurface cryosalt expansion and collapse as trigger for landslides

Area of Science:

• Planetary Science
• Geochemistry
• Soil Science

Background:

• Recurring slope lineae (RSL) are seasonal features on Mars, observed on sun-facing slopes and linked to salts.
• On Earth, reactions between gypsum and chloride salts cause significant ground instability, including sinkholes and debris flows.

Purpose of the Study:

• To investigate the disruptive potential of sulfate-chloride reactions in Martian soil analogs.
• To understand the formation of water-ice slush films on salty Martian soil grains at low temperatures.
• To determine the influence of mixed sulfate and chlorine salts on their solubility in cold environments.
• To assess the contribution of these salt brines to RSL formation on Mars.

Main Methods:

• Laboratory soil crust experiments simulating Martian conditions.
• Analysis of thin films of mixed ice-liquid water (slush) on analog grains at -40°C to -20°C.
• Solubility studies of sulfate and chlorine salt mixtures in low-temperature environments.

Main Results:

• Sulfate-chloride reactions in fine-grained soils can absorb water, expand, and deliquesce.
• Thin films of water slush form on salty Martian analog grains at temperatures between -40°C and -20°C.
• These salt-soil interactions lead to surface disruption, crust formation, and subsidence.
• Dust loading on these unstable surfaces can trigger landslides.

Conclusions:

• Interactions between sulfates and chlorine salts in Martian soils are a plausible mechanism for RSL formation.
• These reactions can create unstable ground conditions conducive to surface disruption and landslides on Mars.
• The findings highlight the dynamic role of salt chemistry in Martian geomorphology.