Plumes of methane identified on Mars.
Published online 21 October 2008 | 455, 1018 (200
|
"Whether the methane plumes are biological or geological in origin is impossible to know at the moment, says Atreya. For example, microbes could be living in deep groundwater below a perma-frost zone, and
their waste methane could percolate up and leak out. The methane could also come from chemical reactions in which buried volcanic rocks rich in the mineral olivine interact with water. A third possibility is that the methane is escaping from buried clathrates, deposits of methane ice formed long ago by one of the other two mechanisms."
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This is a major big deal if confirmed. Especially interesting is that high concentrations were found in the area Nili Fossae. A report presented at the "Workshop on Martian Phyllosilicates: Recorders of
Aqueous Processes?" this month argues that carbonate best fits the spectra in some deposits in the Nili Fossae region on Mars:
PHYLLOSILICATES, ZEOLITES, AND CARBONATE NEAR NILI FOSSAE, MARS: EVIDENCE FOR DISTINCT ENVIRONMENTS OF AQUEOUS ALTERATION.
B.L. Ehlmann1, J.F. Mustard1, G.A. Swayze2, J.J. Wray3, O.S. Barnouin-Jha4, J.L.Bishop5, D.J. Des Marais6, F. Poulet7, L.H. Roach1, R.E. Milliken8, R.N. Clark2, S.L. Murchie4, and the MRO CRISM Team. 1Dept. of Geological Sciences, Brown University, 2U.S. Geological Survey, Denver, 3Cornell University, 4JHU-Applied Physics Laboratory 5SETI Institute 6NASA Ames 7IAS, Université Paris-Sud, 8JPL-Caltech (*...@brown.edu).
Martian Phyllosilicates: Recorders of Aqueous Processes (200
.
http://www.lpi.usra.edu/meetings/aqueous2008/pdf/7019.pdf
However, there are some discrepancies from a pure carbonate spectra in the spectra from the deposits in Nili Fossae that prevents the
researchers from making a definitive identification. Because of this, they offered some other possible explanations here:
NEW SECONDARY MINERALS DETECTED BY MRO CRISM AND THEIR GEOLOGIC SETTINGS: KAOLINITE, CHLORITE, ILLITE/MUSCOVITE, AND THE POSSIBILITY OF SERPENTINE OR CARBONATE IN NILI FOSSAE.
B.L. Ehlmann1, J.F. Mustard1, J.L. Bishop2, G.A. Swayze3, S.M. Pelkey1, R.N. Clark3, R.E. Milliken4, F. Poulet5, W.M. Calvin6, S.L. Murchie7, L.H. Roach1, J.L. Griffes8 and the MRO CRISM Team. 1Dept. of Geological Sciences, Brown University (*...@brown.edu), 2SETI Institute 3U.S. Geological Survey, Denver 4JPL-Caltech 5IAS, Université Paris-Sud 6Dept. of Geological Sciences and Engineering, University of Nevada, Reno, 7JHU-Applied Physics Laboratory 8CEPS,
Smithsonian Institution.
Seventh International Conference on Mars.
http://www.lpi.usra.edu/meetings/7thmars2007/pdf/3270.pdf
Most notable in regard to the methane detection in Nili Fossae is that one of the alternative explanations for the deposits is serpentine. Interestingly, serpentine can arise from aqueous alteration of olivine, and olivine was also seen in Nili Fossae in close proximity to these deposits:
Serpentinite.
"In the presence of carbon dioxide, however, serpentinitization may form either magnesite (MgCO3) or generate methane (CH4). It is thought that some hydrocarbon gases may be produced by serpentinite reactions within the oceanic crust, and the serpentinite reaction is a key argument for the theory of abiogenic petroleum origin.
Reaction 2a:
Olivine + Water + Carbonic acid → Serpentine + Magnetite + Methane
(Fe,Mg)_2SiO_4 + nH_2O + CO_2 → Mg_3Si_2O_5(OH)_4 + Fe_3O_4 + CH_4
or, in balanced form: 18Mg2SiO4 + 6Fe2SiO4 + 26H2O + CO2 →
12Mg3Si2O5(OH)4 + 4Fe3O4 + CH4"
http://en.wikipedia.org/wiki/Serpentinite
If the methane is being produced continually in this area, this could mean this process requiring liquid water is ongoing on Mars.
Bob Clark
