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Ancient Martian nitrogen
Author(s) -
Marti K.,
Mathew K. J.
Publication year - 2000
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/1999gl011064
Subject(s) - martian , meteorite , atmosphere of mars , astrobiology , atmosphere (unit) , nitrogen , isotopes of nitrogen , isotope fractionation , geology , mars exploration program , isotope , fractionation , isotopes of argon , chemistry , physics , organic chemistry , quantum mechanics , thermodynamics
The isotopic signatures and elemental ratios of nitrogen, argon and xenon determined in shock‐melted glass in shergottite meteorites were found to closely resemble the Viking spacecraft data for the present Martian atmosphere. Searches for early signatures, before the Martian atmosphere was subjected to fractionation mechanisms, can be carried out on Martian meteorite ALH84001 and show that nitrogen signatures are incompatible with those of the present atmosphere. We report here the identification of two ancient, a distinctly light and an only slightly evolved, nitrogen isotopic signatures (δ 15 N = −30‰ and +4‰, respectively), as well as a correlation with the isotope ratio 129 Xe/ 132 Xe. Since this ratio evolved rapidly during the early history, due to the short (16 million year) half‐life of the extinct precursor 129 I, it serves as a useful time marker.