Martian atmospheric carbon dioxide and weathering products in SNC meteorites

Carr, R. H.; Grady, M. M.; Wright, I. P.; Pillinger, C. T.

doi:10.1038/314248a0

Cited by 125 publications

(69 citation statements)

References 8 publications

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“…Similarly, Treiman et al (1993) described smectite in Lafayette. Carbonate and sulphate minerals were first identified within the EETA79001 martian meteorite (Gooding et al, 1988) although their presence had earlier been inferred through pyrolysis or stepped combustion experiments (Carr et al, 1985;Gooding and Muenow, 1986). Subsequent studies (summarised in Table I) have enabled the mineralogical and stable isotope characteristics to be understood in more detail.…”

Section: Research On Secondary Minerals In Sncs and Models For Their mentioning

confidence: 99%

“…Carbonate concentrations are generally low with between 30 − 60 ppm for the nakhlites (Grady et al, 1997). Carbon isotope results fall into two groups: ALH84001 and the nakhlites all contain 13 C-enriched carbonates, with δ 13 C ranging from +10‰ to +55‰ (Carr et al, 1985;Wright et al, 1992;Romanek et al, 1994;Jull et al, 1995), whereas Chassigny and the shergottites have acid-extractable carbon, presumably from the carbonate anion, with δ 13 C ranging from 0‰ to −30‰. The most extensive study has been undertaken on ALH84001.…”

Section: Carbon Hydrogen and Sulphurmentioning

confidence: 99%

“…The two clear isotopic groups of carbonate are interpreted to represent formation of the minerals in two different environments: the lighter δ 13 C values are from carbonate formed at depth within the martian crust by interaction of primary magmatic fluids with host rock, whereas carbonates in ALH84001 and the nakhlites formed either at, or close to Mars' surface, where fluid exchanged with martian atmospheric CO 2 (Carr et al, 1985;Wright et al, 1992;Romanek et al, 1994). The carbon isotopic composition of martian atmospheric CO 2 is known to be 13 C-enriched, but a precise measurement of its δ 13 C is still awaited.…”

Section: Carbon Hydrogen and Sulphurmentioning

confidence: 99%

“…The first isotopic analyses of secondary minerals in SNCs were obtained through the stepped combustion experiments (Carr et al, 1985). Analysis of EETA79001 suggested the possibility of two components of 13 C-enriched carbon, one from carbonate, the second with δ 13 C ∼+36‰, from trapped martian atmospheric CO 2 .…”

Section: Research On Secondary Minerals In Sncs and Models For Their mentioning

confidence: 99%

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Bridges

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Saxton

et al. 2001

Space Science Reviews

218

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Abstract. The SNC (Shergotty-Nakhla-Chassigny) meteorites have recorded interactions between martian crustal fluids and the parent igneous rocks. The resultant secondary minerals -which comprise up to ~ 1 vol.% of the meteorites -provide information about the timing and nature of hydrous activity and atmospheric processes on Mars. We suggest that the most plausible models for secondary mineral formation involve the evaporation of low temperature (25-150 o C) brines. This is consistent with the simple mineralogy of these assemblages -Fe-Mg-Ca carbonates, anhydrite, gypsum, halite, clays -and the chemical fractionation of Ca-to Mg-rich carbonate in ALH84001 'rosettes'. Longer-lived, and higher temperature, hydrothermal systems would have caused more silicate alteration than is seen and probably more complex mineral assemblages. Experimental and phase equilibria data on carbonate compositions similar to those present in the SNCs imply low temperatures of formation with cooling taking place over a short period of time (e.g. days). The ALH84001 carbonate also probably shows the effects of partial vapourisation and dehydration related to an impact event postdating the initial precipitation. This shock event may have led to the formation of sulphide and some magnetite in the Fe-rich outer parts of the rosettes.Radiometric dating (K-Ar, Rb-Sr) of the secondary mineral assemblages in one of the nakhlites (Lafayette) suggests that they formed between 0 and 670 Ma, and certainly long after the crystallisation of the host igneous rocks. Crystallisation of ALH84001 carbonate took place 0.5 Ga after the parent rock. These age ranges and the other research on these assemblages suggest that environmental conditions conducive to near-surface liquid water have been present on Mars periodically over the last ~1 Ga. This fluid activity cannot have been continuous over geological time because in that case much more silicate alteration would have taken place in the meteorite parent rocks and the soluble salts would probably not have been preserved.The secondary minerals could have been precipitated from brines with seawater-like composition, high bicarbonate contents and a weakly acidic nature. The co-existence of siderite (Fe-carbonate) and clays in the nakhlites suggests that the pCO 2 level in equilibrium with the parent brine may have been 50 mbar or more. The brines could have originated as flood waters which percolated through the top few hundred metres of the crust, releasing cations from the surrounding parent rocks. There is no spectroscopic or photographic evidence for extensive evaporite deposits on the current martian surface but some salt precipitation through solute concentration must have occurred as floodwaters associated with many of the martian channels ponded in low-lying areas. The high sulphur and chlorine concentrations of the martian soil have most likely resulted from aeolian redistribution of such aqueously-deposited salts and from reaction of the martian surface with volcanic acid volatiles. However, the SNC...

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Section: Research On Secondary Minerals In Sncs and Models For Their mentioning

confidence: 99%

Section: Carbon Hydrogen and Sulphurmentioning

confidence: 99%

Section: Carbon Hydrogen and Sulphurmentioning

confidence: 99%

Section: Research On Secondary Minerals In Sncs and Models For Their mentioning

confidence: 99%

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Bridges

Catling

Saxton

et al. 2001

Space Science Reviews

218

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“…The fact that the secondary minerals are found in meteorites that were collected immediately following their observed fall implies that the meteorites were altered by weathering on Mars' surface. Associated with the secondary products are low concentrations of Martian organic material (Carr et al 1985). It has thus been suggested that nakhlites might contain evidence for a Martian biosphere (Wright et al 1989).…”

Section: Water On Mars : Evidence From Meteoritesmentioning

confidence: 99%

WatSen: searching for clues for water (and life) on Mars

Grady

2006

International Journal of Astrobiology

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: There is plenty of evidence for fluid on Mars : large-scale (planet-wide) features have been captured over four decades by a procession of orbiting satellites equipped with cameras with increasingly higher spatial resolutions. Imagery of the surface shows channels, valleys, ice-caps, etc. Small-scale, more local evidence for fluid has come from images obtained by rovers on the Martian surface. Images that water produced many of the features are supported by spectroscopic measurements (again both planet-wide and local) over a range of wavelengths, which show the presence of minerals generally only produced in the presence of water (haemetite, jarosite, etc.). Results from meteorites continue this picture of fluid activity taking place over significant periods of Mars' history. Despite all these indicators of water, direct detection of water has never been performed. We have reviewed the evidence for water on Mars' surface, and have described WatSen, a combined humidity sensor and infrared IR detector, which can be employed to search for water at and below Mars' surface. WatSen is designed to be part of the suite of instruments on the mole that will be deployed as part of the Geophysics and Environment Package on ExoMars. The objectives of the package are as follows : (i) to detect water within Martian soil by measuring humidity and IR spectral characteristics of the substrate at surface and at depth ; (ii) to determine the mineralogy and mineral chemistry of surface soils (this measurement will provide the mineralogical context for the elemental results that come from other instruments mounted on the landing platform); (iii) to determine how mineralogy changes with depth. The utility of WatSen is that it will not only detect the presence of water, but will also be able to record which minerals are present and their chemistry ; it is also sensitive to many organic species. WatSen is a new instrument concept specifically designed to search for clues of the presence of water, and to look for evidence of life on Mars.

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Alteration of the carbon and nitrogen isotopic composition in the Martian surface rocks due to cosmic ray exposure

Павлов

Ostryakov

et al. 2014

JGR Planets

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13 C/ 12 C and 15 N/ 14 N isotopic ratios are pivotal for our understanding of the Martian carbon cycle, history of the Martian atmospheric escape, and origin of the organic compounds on Mars. Here we demonstrate that the carbon and nitrogen isotopic composition of the surface rocks on Mars can be significantly altered by the continuous exposure of Martian surface to cosmic rays. Cosmic rays can effectively produce 13 C and 15 N isotopes via spallation nuclear reactions on oxygen atoms in various Martian rocks. We calculate that in the top meter of the Martian rocks, the rates of production of both 13 C and 15 N due to galactic cosmic rays (GCRs) exposure can vary within 1.5-6 atoms/cm 3 /s depending on rocks' depth and chemical composition. We also find that the average solar cosmic rays can produce carbon and nitrogen isotopes at a rate comparable to GCRs in the top 5-10 cm of the Martian rocks. We demonstrate that if the total carbon content in a surface Martian rock is <10 ppm, then the "light," potentially "biological" 13 C/ 12 C ratio would be effectively erased by cosmic rays over 3.5 billion years of exposure. We found that for the rocks with relatively short exposure ages (e.g., 100 million years), cosmogenic changes in 15 N/ 14 N ratio are still very significant. We also show that a short exposure to cosmic rays of Allan Hills 84001 while on Mars can explain its high-temperature heavy nitrogen isotopic composition ( 15 N/ 14 N). Applications to Martian meteorites and the current Mars Science Laboratory mission are discussed.

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Martian atmospheric carbon dioxide and weathering products in SNC meteorites

Cited by 125 publications

References 8 publications

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WatSen: searching for clues for water (and life) on Mars

Alteration of the carbon and nitrogen isotopic composition in the Martian surface rocks due to cosmic ray exposure

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