The recurring slope lineae on Mars have been hypothesized to originate from snow melting, deliquescence, dry flow or shallow groundwater. Except for the dry flow origin, these hypotheses imply the presence of surficial or near-surface volatiles, placing the exploration and characterization of potential habitable environments within the reach of existing technology. Here we present observations from the High Resolution Imaging Science Experiment, heat-flow modelling and terrestrial analogues, which indicate that the source of recurring slope lineae could be natural discharge along geological structures from briny aquifers within the cryosphere, at depths of approximately 750 m. Spatial correlation between recurring slope lineae source regions and multi-scale fractures (such as joints and faults) in the southern mid-latitudes and in Valles Marineris suggests that recurring slope lineae preferably emanate from tectonic and impact-related fractures. We suggest that deep groundwater occasionally surfaces on Mars in present-day conditions.
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The authors declare that the data supporting the findings of this study are available within the article and its Supplementary Information.
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The authors are grateful to M. Sultan from Western Michigan University, R. Elkadiri from Middle Tennessee State University, H. El Safty from USC and Y. Gim from JPL for the discussions that helped to generate this manuscript. The first author is a postdoctoral research associate currently funded by the University of Southern California under the NASA Planetary Geology and Geophysics award NNX15AV76G awarded to the principal investigator E.H.
The authors declare no competing interests.
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Abotalib, A.Z., Heggy, E. A deep groundwater origin for recurring slope lineae on Mars. Nat. Geosci. 12, 235–241 (2019). https://doi.org/10.1038/s41561-019-0327-5
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