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Noble gases and nitrogen in Raghunathpura ( IIAB ) and Nyaung ( IIIAB ) iron meteorites
Author(s) -
Murty S. V. S.,
Ghosh S.,
Ray Dwijesh
Publication year - 2019
Publication title -
meteoritics and planetary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.09
H-Index - 100
eISSN - 1945-5100
pISSN - 1086-9379
DOI - 10.1111/maps.13195
Subject(s) - meteorite , iron meteorite , noble gas , meteoroid , nitrogen , chemistry , parent body , analytical chemistry (journal) , chondrite , astrobiology , physics , environmental chemistry , organic chemistry
Noble gases and nitrogen were measured in two adjacent samples each from the Raghunathpura ( IIAB ) and the Nyaung ( IIIAB ) iron meteorite falls. Light noble gases in both the meteorites were of pure cosmogenic origin. Using ( 3 He/ 4 He) c ratios and the production systematic of Ammon et al. ([Ammon K., 2009]), we estimated the sample depth and meteoroid size for Nyaung (~8 cm depth in a ~15 cm radius object) and Raghunathpura (~12–14 cm depth in a ~25 cm object). We derived cosmic ray exposure ages of 1710 ± 256 Ma (for Nyaung, the highest reported so far for the IIIAB group) and 224 ± 34 Ma (for Raghunathpura). Variable amounts of trapped Kr and Xe were found in both meteorites. The phase Q‐like elemental ratio ( 84 Kr/ 132 Xe) suggests that the trapped component is of indigenous origin, and most likely hosted in the heterogeneously distributed micro‐inclusions of troilite/schreibersite. Trapped phase Q component is being reported for the first time, for a IIAB iron meteorite. Both meteorites showed light isotopic composition for nitrogen, and need at least two N components to explain the observed N isotopic systematic. Variable amounts of trapped noble gases and the presence of more than one N component suggest that the magmatic process that formed the parent body of these meteorites either could not completely homogenize or completely degas all the phases.