title: Isotopic evidence for a terrestrial source of organic compounds found in martian meteorites Allan Hills 84001 and Elephant Moraine 79001.
abstract: Stepped-heating experiments on martian meteorites Allan Hills 84001 (ALH84001) and Elephant Moraine 79001 (EETA79001) revealed low-temperature (200 to 430 degrees Celsius) fractions with a carbon isotopic composition delta13C between -22 and -33 per mil and a carbon-14 content that is 40 to 60 percent of that of modern terrestrial carbon, consistent with a terrestrial origin for most of the organic material. Intermediate-temperature (400 to 600 degrees Celsius) carbonate-rich fractions of ALH84001 have delta13C of +32 to +40 per mil with a low carbon-14 content, consistent with an extraterrestrial origin, whereas some of the carbonate fraction of EETA79001 is terrestrial. In addition, ALH84001 contains a small preterrestrial carbon component of unknown origin that combusts at intermediate temperatures. This component is likely a residual acid-insoluble carbonate or a more refractory organic phase.
authors.affiliation: National Science Foundation-Arizona Accelerator Mass Spectrometer Facility, University of Arizona, Tucson, AZ 85721, USA.
authors.forename: A J
authors.initials: AJ
authors.lastname: Jull
authors.forename: C
authors.initials: C
authors.lastname: Courtney
authors.forename: D A
authors.initials: DA
authors.lastname: Jeffrey
authors.forename: J W
authors.initials: JW
authors.lastname: Beck
mesh_terms: D002244:Carbon / Q000032:analysis*; D002245:Carbon Dioxide / Q000032:analysis / Q000737:chemistry; D002247:Carbon Isotopes; D002250:Carbon Radioisotopes; D002254:Carbonates / Q000032:analysis / Q000737:chemistry; D006358:Hot Temperature; D018535:Mars; D019110:Meteoroids; D009930:Organic Chemicals / Q000032:analysis* / Q000737:chemistry; D017640:Silicates / Q000032:analysis / Q000737:chemistry
chemical_list: D002247:Carbon Isotopes; D002250:Carbon Radioisotopes; D002254:Carbonates; D009930:Organic Chemicals; D017640:Silicates; D002245:Carbon Dioxide; D002244:Carbon