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Initiation and flow conditions of contemporary flows in Martian gullies

Haas, T.; McArdell, B.W.; Conway, S.J.; McElwaine, J.N.; Kleinhans, M.G.; Salese, F.; Grindrod, P.M.

Initiation and flow conditions of contemporary flows in Martian gullies Thumbnail


Authors

T. Haas

B.W. McArdell

S.J. Conway

M.G. Kleinhans

F. Salese

P.M. Grindrod



Abstract

Understanding the initial and flow conditions of contemporary flows in Martian gullies, generally believed to be triggered and fluidized by CO2 sublimation, is crucial for deciphering climate conditions needed to trigger and sustain them. We employ the RAMMS (RApid Mass Movement Simulation) debris flow and avalanche model to back‐calculate initial and flow conditions of recent flows in three gullies in Hale crater. We infer minimum release depths of 1.0‐1.5 m and initial release volumes of 100‐200 m3. Entrainment leads to final flow volumes that are ~2.5‐5.5 times larger than initially released, and entrainment is found necessary to match the observed flow deposits. Simulated mean cross‐channel flow velocities decrease from 3‐4 m s‐1 to ~1 m s‐1 from release area to flow terminus, while flow depths generally decrease from 0.5‐1 m to 0.1‐0.2 m. The mean cross‐channel erosion depth and deposition thicknesses are ~0.1‐0.3 m. Back‐calculated dry‐Coulomb friction ranges from 0.1 to 0.25 and viscous‐turbulent friction between 100‐200 m s‐2, which are values similar to those of granular debris flows on Earth. These results suggest that recent flows in gullies are fluidized to a similar degree as are granular debris flows on Earth. Using a novel model for mass‐flow fluidization by CO2 sublimation we are able to show that under Martian atmospheric conditions very small volumetric fractions of CO2 of ≪1% within mass flows may indeed yield sufficiently large gas fluxes to cause fluidization and enhance flow mobility.

Citation

Haas, T., McArdell, B., Conway, S., McElwaine, J., Kleinhans, M., Salese, F., & Grindrod, P. (2019). Initiation and flow conditions of contemporary flows in Martian gullies. Journal of Geophysical Research: Planets, 124(8), 2246-2271. https://doi.org/10.1029/2018je005899

Journal Article Type Article
Acceptance Date Jul 26, 2019
Online Publication Date Aug 28, 2019
Publication Date Aug 31, 2019
Deposit Date Aug 2, 2019
Publicly Available Date Mar 29, 2024
Journal Journal of Geophysical Research: Planets
Print ISSN 2169-9097
Electronic ISSN 2169-9100
Publisher American Geophysical Union
Peer Reviewed Peer Reviewed
Volume 124
Issue 8
Pages 2246-2271
DOI https://doi.org/10.1029/2018je005899

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Publisher Licence URL
http://creativecommons.org/licenses/by/4.0/

Copyright Statement
© 2019. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.




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