Production of anomalous Xe in nanodiamond in chondrites during the last supernova explosion predating the origin of the Solar System |
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| Authors: | G K Ustinova |
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| Institution: | 1.Vernadsky Institute of Geochemistry and Analytical Chemistry,Russian Academy of Sciences,Moscow,Russia |
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| Abstract: | Anomalous Xe enriched in both heavy and light isotopes (Xe-HL) was identified in the high-temperature Xe fraction in relict nanodiamond grains from chondrites, whereas the low-temperature
Xe fraction (Xe-P3) typically has the normal isotopic composition. The paper presents a concise review of current models put forth to account
for the genesis of nanodiamond with anomalous noble gas components and specifies a real process and major regularities during
the generation of the isotopic relations of the anomalous Xe-HL component in relict nanodiamond grains. This component is demonstrated to be formed and captured simultaneously with the
synthesis of nanodiamond, when shock waves induced by supernova explosions propagated. It is important that diamond synthesis
during the passage of shock waves and the enrichment of this diamond in Xe-HL are also possible in the wave forefront region under extremal P-T conditions, in the pressure drop region behind the wave front (by means of nucleation), and by means of irradiation of carbonic
grains with high-energy particles. The isotopic composition of Xe-HL results from an increase in the hardness of the spectrum of nuclear-active particles and its enrichment in heavy ions at
acceleration in shock waves. Arguments are presented in support of the hypothesis that the nanodiamond population found in
chondrites was produced during the latest supernova explosion before the development of the Solar System, with the supernova
likely being a SnIa carbon detonation supernova. This furnishes evidence in support of recently advanced hypotheses that the
nanodiamond population of chondrites is not presolar. |
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