Depleted carbon isotope compositions observed at Gale crater, Mars

Christopher H. House, Gregory M. Wong, Christopher R. Webster, Gregory J. Flesch, Heather B. Franz, Jennifer C. Stern, Alex Pavlov, Sushil K. Atreya, Jennifer L. Eigenbrode, Alexis Gilbert, Amy E. Hofmann, Maëva Millan, Andrew Steele, Daniel P. Glavin, Charles A. Malespin, Paul R. Mahaffy

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


Obtaining carbon isotopic information for organic carbon from Martian sediments has long been a goal of planetary science, as it has the potential to elucidate the origin of such carbon and aspects of Martian carbon cycling. Carbon isotopic values (δ13CVPDB) of the methane released during pyrolysis of 24 powder samples at Gale crater, Mars, show a high degree of variation (2137 ± 8 to +22 ± 10 ) when measured by the tunable laser spectrometer portion of the Sample Analysis at Mars instrument suite during evolved gas analysis. Included in these data are 10 measured δ13C values less than270 found for six different sampling locations, all potentially associated with a possible paleosurface. There aremultiple plausible explanations for the anomalously depleted 13C observed in evolved methane, but no single explanation can be acceptedwithout further research. Three possible explanations are the photolysis of biological methane released from the subsurface, photoreduction of atmospheric CO2, and deposition of cosmic dust during passage through a galactic molecular cloud. All three of these scenarios are unconventional, unlike processes common on Earth.

Original languageEnglish (US)
Article numbere2115651119
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number4
StatePublished - Jan 25 2022

All Science Journal Classification (ASJC) codes

  • General


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