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Granular flows at recurring slope lineae on Mars indicate a limited role for liquid water

Dundas, Colin M.; McEwen, Alfred S.; Chojnacki, Matthew; Milazzo, Moses P.; Byrne, Shane; McElwaine, Jim N.; Urso, Anna

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Authors

Colin M. Dundas

Alfred S. McEwen

Matthew Chojnacki

Moses P. Milazzo

Shane Byrne

Anna Urso



Abstract

Recent liquid water flow on Mars has been proposed based on geomorphological features, such as gullies. Recurring slope lineae — seasonal flows that are darker than their surroundings — are candidate locations for seeping liquid water on Mars today, but their formation mechanism remains unclear. Topographical analysis shows that the terminal slopes of recurring slope lineae match the stopping angle for granular flows of cohesionless sand in active Martian aeolian dunes. In Eos Chasma, linea lengths vary widely and are longer where there are more extensive angle-of-repose slopes, inconsistent with models for water sources. These observations suggest that recurring slope lineae are granular flows. The preference for warm seasons and the detection of hydrated salts are consistent with some role for water in their initiation. However, liquid water volumes may be small or zero, alleviating planetary protection concerns about habitable environments.

Citation

Dundas, C. M., McEwen, A. S., Chojnacki, M., Milazzo, M. P., Byrne, S., McElwaine, J. N., & Urso, A. (2017). Granular flows at recurring slope lineae on Mars indicate a limited role for liquid water. Nature Geoscience, 10, 903-907. https://doi.org/10.1038/s41561-017-0012-5

Journal Article Type Article
Acceptance Date Oct 23, 2017
Online Publication Date Nov 20, 2017
Publication Date Nov 20, 2017
Deposit Date Nov 23, 2017
Publicly Available Date May 20, 2018
Journal Nature Geoscience
Print ISSN 1752-0894
Electronic ISSN 1752-0908
Publisher Nature Research
Peer Reviewed Peer Reviewed
Volume 10
Pages 903-907
DOI https://doi.org/10.1038/s41561-017-0012-5

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