Spectral Nature of CO2 Adsorption onto Meteorites
Genesis Berlanga, Charles A. Hibbitts, Driss Takir, M. Darby Dyar, Elizabeth Sklute
In Press, Accepted Manuscript, Available online 5 July 2016
• We report on CO2 gas adsorption experiments on carbonaceous chondrite meteorites.
• Experiments were run at cryogenic temperatures.
• CI Chondrite Ivuna adsorbed significantly more CO2 than the other non-CI meteorites.
• CO2 abundance does not vary with ‘water,’ organic, nor carbonate abundances.
• Possible affinity of CO2 for complex clays and total FeO.Spectral Nature of CO2 Adsorption onto Meteorites.
“Previous studies have identified carbon dioxide (CO2) on the surfaces of Jovian and Galilean satellites in regions of non-ice material that are too warm for CO2 ice to exist. CO2 ice would quickly sublimate if not retained by a less-volatile material. To ascertain what non-ice species may be responsible for stabilizing this CO2, we performed CO2 gas adsorption experiments on thirteen powdered CM, CI, and CV carbonaceous chondrite meteorites. Reflectance spectra of the ν3 feature associated with adsorbed CO2 near 4.27 μm were recorded. Results show that many meteorites adsorbed some amount of CO2, as evidenced by an absorption feature that was stable over several hours at ultra-high vacuum (UHV) and high vacuum, (1.0×10−8 and 1.0×10−7 Torr, respectively). Ivuna, the only CI chondrite studied, adsorbed significantly more CO2 than the others. We found that CO2 abundance did not vary with ‘water’ abundance, organics, or carbonates as inferred from the area of the 3-μm band, the 3.2-3.4 μm C-H feature, and the ∼3.8-μm band respectively, but did correlate with hydrous/anhydrous phyllosilicate ratios. Furthermore, we did not observe CO2 ice because the position of the CO2 feature was generally shifted 3-10 nm from that of the 4.27 μm absorption characteristic of ice. The strongest compositional relationship observed was a possible affinity of CO2 for total FeO abundance and complex clay minerals, which make up the bulk of the CI chondrite matrix. This finding implies that the most primitive refractory materials in the Solar System may also act as reservoirs of CO2, and possibly other volatiles, delivering them to parts of the Solar System where their ices would not be stable.”