Isotopic Composition of Noble Gases, Nitrogen, and Carbon in the Ozerki New L Chondrite
- PDF / 2,136,131 Bytes
- 18 Pages / 612 x 792 pts (letter) Page_size
- 28 Downloads / 180 Views
opic Composition of Noble Gases, Nitrogen, and Carbon in the Ozerki New L Chondrite E. V. Korochantsevaa, *, A. B. Verchovskyb, A. I. Buikina, *, K. A. Lorentsa, and A. V. Korochantseva aVernadsky
Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, Moscow, 119991 Russia bThe Open University, Walton Hall, Milton Keynes, MK7 6AA, United Kingdom *e-mail: [email protected] Received April 2, 2020; revised April 30, 2020; accepted May 2, 2020
Abstract—The isotopic composition of noble gases, nitrogen, and carbon in two samples of the Ozerki L chondrite, which differ in the degree of impact metamorphism, analyzed by the methods of stepwise oxidation and crushing, is reported. The data obtained indicate that the meteorite contains gases trapped on the asteroid during the impact events. The isotopic composition of trapped argon, studied by the stepwise crushing method, is dominated by radiogenic 40Ar (the average 40Ar/36Ar values are 846 in the chondrite material and 1908 in the melt with fine chondrite fragments). Most of the trapped 36Ar is located in positions inaccessible for crushing. The isotopic composition of Ne is a mixture of the solar-wind neon, cosmogenic, and most likely planetary (Q) components. The elemental composition of the trapped noble gases is formed by mixing of the solar, planetary (Q), and cosmogenic components in different proportions. Diffusion processes caused by impact events most likely influenced the elemental abundance of noble gases, primarily helium. Almost all carbon and nitrogen are chemically bound in the rock. In general, their isotopic composition corresponds to that of ordinary chondrites; however, an atypically light carbon isotopic composition with a bulk value δ13C = –47.6 ± 4.8 (‰) was detected in a sample of the chondrite material. The nitrogen released during crushing is isotopically lighter than that released during oxidation. This may indicate that in the course of impact processes, solar nitrogen is more easily mobilized and redistributed into voids than organic nitrogen enriched in the heavy isotope. Keywords: meteorites, L chondrite, noble gases, nitrogen, carbon, stepwise crushing and oxidation DOI: 10.1134/S0016702920110075
INTRODUCTION The Ozerki chondrite fell as a meteorite shower on June 21, 2018 in the Lipetsk region, Russia. More than 100 pieces of it were found. The total collected weight of the meteorite exceeds 10 kg. Based on the results of petrographic analysis, the meteorite was classified as ordinary chondrite (L6); shock stage S5; weathering class W0 (Meteoritical Bulletin, 2018). The Ozerki meteorite immediately attracted attention and was studied actively by several groups of scientists (Alekseev et al., 2019; Efimov et al., 2019; Muftakhetdinova et al., 2019; Smith et al., 2019; Maksimova et al., 2020). The track studies showed absence of tracks formed upon irradiation by galactic cosmic rays in olivine grains, most likely due to the low age of the cosmic exposure of this meteorite and/or a deep location of the studied sample (
Data Loading...
