Independent confirmation of a methane spike on Mars and a source region east of Gale Crater

Giuranna, M.; Viscardy, S.; Daerden, Frank; Neary, L.; Etiope, Giuseppe; Oehler, Dorothy Z.; Formisano, V.; Aronica, A.; Wolkenberg, P.; Aoki, Shohei; Cardesín‐Moinelo, Alejandro; Parra, Julia Marín-Yaseli de la; Merritt, Donald; Amoroso, Marilena

doi:10.1038/s41561-019-0331-9

Cited by 79 publications

(105 citation statements)

References 68 publications

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“…An intriguing aspect of H 2 and CH 4 formation in fluid inclusions is that these reduced volatiles can be stored over geological timescales and extracted at a later point in time, even after hydrothermal activity has ceased or when liquid water is no longer present. Such a process may be particularly relevant to sources of CH 4 on Mars where spikes in atmospheric CH 4 have been reported (36) and recently confirmed (37), even though Mars has lost much of its atmosphere and liquid water. Furthermore, if Mars is still seismically active (38), CH 4 could be extracted through continual or episodic fracturing of the host rock.…”

Section: Summary and Implicationsmentioning

confidence: 91%

Abiotic methane synthesis and serpentinization in olivine-hosted fluid inclusions

Klein

Grozeva

Seewald

2019

Proc. Natl. Acad. Sci. U.S.A.

141

128

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The conditions of methane (CH4) formation in olivine-hosted secondary fluid inclusions and their prevalence in peridotite and gabbroic rocks from a wide range of geological settings were assessed using confocal Raman spectroscopy, optical and scanning electron microscopy, electron microprobe analysis, and thermodynamic modeling. Detailed examination of 160 samples from ultraslow- to fast-spreading midocean ridges, subduction zones, and ophiolites revealed that hydrogen (H2) and CH4 formation linked to serpentinization within olivine-hosted secondary fluid inclusions is a widespread process. Fluid inclusion contents are dominated by serpentine, brucite, and magnetite, as well as CH4(g) and H2(g) in varying proportions, consistent with serpentinization under strongly reducing, closed-system conditions. Thermodynamic constraints indicate that aqueous fluids entering the upper mantle or lower oceanic crust are trapped in olivine as secondary fluid inclusions at temperatures higher than ∼400 °C. When temperatures decrease below ∼340 °C, serpentinization of olivine lining the walls of the fluid inclusions leads to a near-quantitative consumption of trapped liquid H2O. The generation of molecular H2 through precipitation of Fe(III)-rich daughter minerals results in conditions that are conducive to the reduction of inorganic carbon and the formation of CH4. Once formed, CH4(g) and H2(g) can be stored over geological timescales until extracted by dissolution or fracturing of the olivine host. Fluid inclusions represent a widespread and significant source of abiotic CH4 and H2 in submarine and subaerial vent systems on Earth, and possibly elsewhere in the solar system.

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Section: Summary and Implicationsmentioning

confidence: 91%

Abiotic methane synthesis and serpentinization in olivine-hosted fluid inclusions

Klein

Grozeva

Seewald

2019

Proc. Natl. Acad. Sci. U.S.A.

141

128

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“…Initially, the first near‐surface measurements from the Sample Analysis at Mars Tunable Laser Spectrometer (SAM‐TLS) onboard the Curiosity rover (Webster et al, ; Webster et al, ) reported less than 1.3 ppbv of methane but later reported 7‐ to 9‐ppbv spikes in 2013. Using a spot‐tracking mode from orbit, the Planetary Fourier Spectrometer onboard Mars Express (Giuranna et al, ) simultaneously recorded a 15‐ppbv plume over and around Gale crater. As such, there is strong evidence of episodic and significant emissions of methane on Mars of perhaps as much as 19,000 tons of material at a time (Mumma et al, ).…”

Section: Introductionmentioning

confidence: 99%

“…While the methane concentration in this layer may be high, the total mass of methane required to produce the SAM‐TLS signal would be relatively small and once the PBL begins to build again at dawn would be mixed away, nearly to the background level observed by TGO. Indeed, because the mass of methane involved is so low, much lower than the mass of a plume, it would be invisible to nadir‐pointing orbital observations (e.g., Giuranna et al, ).…”

Section: Introductionmentioning

confidence: 99%

The Methane Diurnal Variation and Microseepage Flux at Gale Crater, Mars as Constrained by the ExoMars Trace Gas Orbiter and Curiosity Observations

Moores

King

Smith

et al. 2019

Geophysical Research Letters

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The upper bound of 50 parts per trillion by volume for Mars methane above 5 km established by the ExoMars Trace Gas Orbiter, substantially lower than the 410 parts per trillion by volume average measured overnight by the Curiosity Rover, places a strong constraint on the daytime methane flux at the Gale crater. We propose that these measurements may be largely reconciled by the inhibition of mixing near the surface overnight, whereby methane emitted from the subsurface accumulates within meters of the surface before being mixed below detection limits at dawn. A model of this scenario allows the first precise calculation of microseepage fluxes at Gale to be derived, consistent with a constant 1.5 × 10−10 kg·m−2·sol−1 (5.4 × 10−5 tonnes·km−2·year−1) source at depth. Under this scenario, only 2.7 × 104 km2 of Mars's surface may be emitting methane, unless a fast destruction mechanism exists.

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“…These measurements were performed for 5 years at the Gale Crater, and results showed methane was present in the range of 0.24-0.65 ppbv. The spike of methane was also independently detected by the Mars Express orbiter at the Gale Crater a day after data were reported by MSL [100]. However, the most recent study report by Korablev et al [101] did not detect traces of methane in the atmosphere by the ExoMars Trace Gas Orbiter even though it was one of the goals of this mission.…”

Section: Mars Subsurface As a Potential Habitat For Lifementioning

confidence: 62%

Habitability of Mars: How Welcoming Are the Surface and Subsurface to Life on the Red Planet?

Sielaff

Smith

2019

Geosciences

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Mars is a planet of great interest in the search for signatures of past or present life beyond Earth. The years of research, and more advanced instrumentation, have yielded a lot of evidence which may be considered by the scientific community as proof of past or present habitability of Mars. Recent discoveries including seasonal methane releases and a subglacial lake are exciting, yet challenging findings. Concurrently, laboratory and environmental studies on the limits of microbial life in extreme environments on Earth broaden our knowledge of the possibility of Mars habitability. In this review, we aim to: (1) Discuss the characteristics of the Martian surface and subsurface that may be conducive to habitability either in the past or at present; (2) discuss laboratory-based studies on Earth that provide us with discoveries on the limits of life; and (3) summarize the current state of knowledge in terms of direction for future research.

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Independent confirmation of a methane spike on Mars and a source region east of Gale Crater

Cited by 79 publications

References 68 publications

Abiotic methane synthesis and serpentinization in olivine-hosted fluid inclusions

Abiotic methane synthesis and serpentinization in olivine-hosted fluid inclusions

The Methane Diurnal Variation and Microseepage Flux at Gale Crater, Mars as Constrained by the ExoMars Trace Gas Orbiter and Curiosity Observations

Habitability of Mars: How Welcoming Are the Surface and Subsurface to Life on the Red Planet?

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