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Effects of aqueous alteration on primordial noble gases and presolar SiC in the carbonaceous chondrite Tagish Lake
Author(s) -
Riebe M. E. I.,
Busemann H.,
Alexander C. M. O'D.,
Nittler L. R.,
Herd C. D. K.,
Maden C.,
Wang J.,
Wieler R.
Publication year - 2020
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.13383
Subject(s) - presolar grains , noble gas , meteorite , aqueous solution , parent body , graphite , chondrite , chemistry , analytical chemistry (journal) , astrobiology , mineralogy , materials science , environmental chemistry , physics , metallurgy , organic chemistry
Effects of aqueous alteration on primordial noble gas carriers were investigated by analyzing noble gases and determining presolar SiC abundances in insoluble organic matter ( IOM ) from four Tagish Lake meteorite (C2‐ung.) samples that experienced different degrees of aqueous alteration. The samples contained a mixture of primordial noble gases from phase Q and presolar nanodiamonds ( HL , P3), SiC (Ne‐E[H]), and graphite (Ne‐E[L]). The second most altered sample (11i) had a ~2–3 times higher Ne‐E concentration than the other samples. The presolar SiC abundances in the samples were determined from Nano SIMS ion images and 11i had a SiC abundance twice that of the other samples. The heterogeneous distribution of SiC grains could be inherited from heterogeneous accretion or parent body alteration could have redistributed SiC grains. Closed system step etching ( CSSE ) was used to study noble gases in HNO 3 ‐susceptible phases in the most and least altered samples. All Ne‐E carried by presolar SiC grains in the most altered sample was released during CSSE , while only a fraction of the Ne‐E was released from the least altered sample. This increased susceptibility to HNO 3 likely represents a step toward degassing. Presolar graphite appears to have been partially degassed during aqueous alteration. Differences in the 4 He/ 36 Ar and 20 Ne/ 36 Ar ratios in gases released during CSSE could be due to gas release from presolar nanodiamonds, with more He and Ne being released in the more aqueously altered sample. Aqueous alteration changes the properties of presolar grains so that they react similar to phase Q in the laboratory, thereby altering the perceived composition of Q.