In this paper, we report on new 14C and 13C isotopic analyses of organic and carbonate phases in pristine samples of the martian meteorite, Nakhla (fell 1911AD). We undertook water and acid extractions of soluble phases as well as a study of insoluble material. We used 14C to differentiate between extraterrestrial organic material and recent terrestrial contamination. Results indicate that most of the organic matter in Nakhla is released by 6N HCl and there appear to be two isotopically distinct sources of extraterrestrial organics with δ13C of -33‰ and -15‰ and low 14C. We estimate that at least 75% of the organic material released by 6N HCl acid etching is extraterrestrial. We conclude that this acid-labile component is likely similar to polymeric organics observed in CM2 chondrites (Gilmour and Pillinger, 1994) and could have accumulated on the Martian surface from the accumulation of meteoritic material and cometary debris and cosmic dust. We also determined that the terrestrial organic contamination is characterized by approximately modern 14C values and δ13C of -25‰. Copyright (C) 2000 Elsevier Science Ltd.
ASJC Scopus subject areas
- Geochemistry and Petrology