Geophysical Research Letters

Formation of recurring slope lineae by liquid brines on present-day Mars

Authors

  • Vincent F. Chevrier,

    Corresponding author
    1. Arkansas Center for Space and Planetary Sciences, University of Arkansas, Fayetteville, Arkansas, USA
    • Corresponding author: V. Chevrier, Arkansas Center for Space and Planetary Sciences, University of Arkansas, FELD 202, Fayetteville, AR 72701, USA. (vchevrie@uark.edu)

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  • Edgard G. Rivera-Valentin

    1. Department of Geological Sciences, Brown University, Providence, Rhode Island, USA
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Abstract

[1] Recurring Slope Lineae (RSL) are small scale seasonal flow features identified by Mars Reconnaissance Orbiter that present several interesting characteristics such as an albedo contrast, seasonal dependence, and a strong preference for equator-facing slopes. All of these characteristics strongly suggest a thermally driven mechanism such as a liquid triggered or dominated flow. Here we investigate the possibility that these features are formed by melting of brines of various compositions via a combination of thermodynamic and kinetic numerical models. Results suggest that a solution with a freezing temperature of ∼223 K can best reproduce the observed seasonality. Relatively high surface evaporation rates at the RSL locations make the flows quickly disappear over a single season. Our model reproduces well the seasonality of RSL and can explain the preference for equator-facing slopes suggesting that brine flows, and therefore liquids, are possible on a small time and space scale today on Mars. However, if the RSL are indeed formed by brines, it may indicate that a recharge mechanism is active in order to maintain a source of brine over even short geological timescales, which would have important implications for the Martian water cycle.

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