New insights into the heterogeneity of the Tagish Lake meteorite: Soluble organic compositions of variously altered specimens

• Published in: Meteoritics & Planetary Science
• Main Authors: Simkus, Danielle N., Aponte, José C., Elsila, Jamie E., Hilts, Robert W., McLain, Hannah L., Herd, Christopher D. K.
• Other Authors: Killam Trusts, Goddard Space Flight Center, NASA Astrobiology Institute, Natural Sciences and Engineering Research Council of Canada
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2019
• Subjects: Tagish; Tagish Lake
• Online Access: http://dx.doi.org/10.1111/maps.13276; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fmaps.13276; https://onlinelibrary.wiley.com/doi/pdf/10.1111/maps.13276; https://onlinelibrary.wiley.com/doi/full-xml/10.1111/maps.13276

Abstract The Tagish Lake carbonaceous chondrite exhibits a unique compositional heterogeneity that may be attributed to varying degrees of aqueous alteration within the parent body asteroid. Previous analyses of soluble organic compounds from four Tagish Lake meteorite specimens ( TL 5b, TL 11h, TL 11i, TL 11v) identified distinct distributions and isotopic compositions that appeared to be linked to their degree of parent body processing (Herd et al. 2011; Glavin et al. 2012; Hilts et al. 2014). In the present study, we build upon these initial observations and evaluate the molecular distribution of amino acids, aldehydes and ketones, monocarboxylic acids, and aliphatic and aromatic hydrocarbons, including compound‐specific δ 13 C compositions, for three additional Tagish Lake specimens: TL 1, TL 4, and TL 10a. TL 1 contains relatively high abundances of soluble organics and appears to be a moderately altered specimen, similar to the previously analyzed TL 5b and TL 11h lithologies. In contrast, specimens TL 4 and TL 10a both contain relatively low abundances of all of the soluble organic compound classes measured, similar to TL 11i and TL 11v. The organic‐depleted composition of TL 4 appears to have resulted from a relatively low degree of parent body aqueous alteration. In the case of TL 10a, some unusual properties (e.g., the lack of detection of intrinsic monocarboxylic acids and aliphatic and aromatic hydrocarbons) suggest that it has experienced extensive alteration and/or a distinct organic‐depleted alteration history. Collectively, these varying compositions provide valuable new insights into the relationships between asteroidal aqueous alteration and the synthesis and preservation of soluble organic compounds.