Isotopic Evidence for a Martian Regolith Component in Martian Meteorites
نویسندگان
چکیده
Introduction: Noble gas measurements in gas-rich impact-melt (GRIM) glasses in EET79001 shergottite showed that their elemental and isotopic composition is similar to that of the Martian atmosphere [1-3]. The GRIM glasses contain large amounts of Martian atmospheric gases. Those measurements further suggested that the Kr isotopic composition of Martian atmosphere is approximately similar to that of solar Kr. This suggestion was validated by [4] after detailed comparison of the lunar and Martian meteorite noble gas data. Subsequently, Garrison and Bogard [5] carried out improved noble gas measurements on GRIM glasses (,8 and ,104) which showed that the lighter isotopes of Kr in GRIM glasses are slightly enriched relative to the lighter Kr isotopes in solar wind implanted into lunar soils, suggesting a mass-fractionation trend of 0.5-1.0% per amu (Fig. 1). The data-average from [2] and [3] for GRIM glass ,27 shows a slightly lower mass fractionation trend compared to the data-average from [5] for ,8A and ,8B glasses. Considering the uncertainities in the measurements of ,27 and ,8 glasses, we adopt a value of 1.03 for (80 Kr/
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