Methane Seepage on Mars: Where to Look and Why
- Creators
- Oehler, Dorothy Z.
- Etiope, Giuseppe
Abstract
Methane on Mars is a topic of special interest because of its potential association with microbial life. The variable detections of methane by the Curiosity rover, orbiters, and terrestrial telescopes, coupled with methane's short lifetime in the martian atmosphere, may imply an active gas source in the planet's subsurface, with migration and surface emission processes similar to those known on Earth as "gas seepage." Here, we review the variety of subsurface processes that could result in methane seepage on Mars. Such methane could originate from abiotic chemical reactions, thermogenic alteration of abiotic or biotic organic matter, and ancient or extant microbial metabolism. These processes can occur over a wide range of temperatures, in both sedimentary and igneous rocks, and together they enhance the possibility that significant amounts of methane could have formed on early Mars. Methane seepage to the surface would occur preferentially along faults and fractures, through focused macro-seeps and/or diffuse microseepage exhalations. Our work highlights the types of features on Mars that could be associated with methane release, including mud-volcano-like mounds in Acidalia or Utopia; proposed ancient springs in Gusev Crater, Arabia Terra, and Valles Marineris; and rims of large impact craters. These could have been locations of past macro-seeps and may still emit methane today. Microseepage could occur through faults along the dichotomy or fractures such as those at Nili Fossae, Cerberus Fossae, the Argyre impact, and those produced in serpentinized rocks. Martian microseepage would be extremely difficult to detect remotely yet could constitute a significant gas source. We emphasize that the most definitive detection of methane seepage from different release candidates would be best provided by measurements performed in the ground or at the ground-atmosphere interface by landers or rovers and that the technology for such detection is currently available.
Additional Information
© 2017 Dorothy Z. Oehler and Giuseppe Etiope, 2017; Published by Mary Ann Liebert, Inc. This Open Access article is distributed under the terms of the Creative Commons Attribution Noncommercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited. Submitted 1 February 2017; Accepted 14 May 2017; Online Ahead of Print: August 3, 2017. This work had its inception at the "Methane on Mars" 2015–2016 workshops organized by the W.M. Keck Institute for Space Studies. We thank Drs. Stephen Clifford for providing insight into martian heat flow and geothermal conditions, John Parnell for discussions of potential impact-related thermal alteration of organics on Mars, Victoria Hamilton for permission to adapt figures from publications on martian olivine distribution and possible source regions for the Chassigny meteorite, Ken Edgett and Timothy Parker for discussions of martian sediment thicknesses, and Jennifer Blank for comments on an early draft of the manuscript. We are also grateful to reviewers, Drs. Adam Stevens and Angelo Pio Rossi, for their insightful suggestions that significantly improved the manuscript. D.Z.O. was supported by the Planetary Science Institute, Tucson, Arizona, USA; and G.E. was supported by the Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma 2, Roma, Italy.Attached Files
Published - ast.2017.1657.pdf
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Additional details
- Eprint ID
- 79840
- Resolver ID
- CaltechAUTHORS:20170807-092336088
- Planetary Science Institute
- Istituto Nazionale di Geofisica e Vulcanologia
- Created
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2017-08-07Created from EPrint's datestamp field
- Updated
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2021-11-15Created from EPrint's last_modified field
- Caltech groups
- Keck Institute for Space Studies