Amino acids in Antarctic CM1 meteorites and their relationship to other carbonaceous chondrites

Abstract

Abstract-CM2 carbonaceous chondrites are the most primitive material present in the solar system, and some of their subtypes, the CM and CI chondrites, contain up to 2 wt% of organic carbon. The CM2 carbonaceous chondrites contain a wide variety of complex amino acids, while the CI1 meteorites Orgueil and Ivuna display a much simpler composition, with only glycine and β-alanine present in significant abundances. CM1 carbonaceous chondrites show a higher degree of aqueous alteration than CM2 types and therefore provide an important link between the CM2 and CI1 carbonaceous chondrites. Relative amino acid concentrations have been shown to be indicative for parent body processes with respect to the formation of this class of compounds. In order to understand the relationship of the amino acid composition between these three types of meteorites, we have analyzed for the first time three Antarctic CM1 chondrites, Meteorite Hills (MET) 01070, Allan Hills (ALH) 88045, and LaPaz Icefield (LAP) 02277, using gas chromatography-mass spectrometry (GC-MS) and high performance liquid chromatography-fluorescence detection (HPLC-FD). The concentrations of the eight most abundant amino acids in these meteorites were compared to those of the CM2s Murchison, Murray, Mighei, Lewis Cliff (LEW) 90500, ALH 83100, as well as the CI1s Orgueil and Ivuna. The total amino acid concentration in CM1 carbonaceous chondrites was found to be much lower than the average of the CM2s. Relative amino acid abundances were compared in order to identify synthetic relationships between the amino acid compositions in these meteorite classes. Our data support the hypothesis that amino acids in CM-and CI-type meteorites were synthesized under different physical and chemical conditions and may best be explained with differences in the abundances of precursor compounds in the source regions of their parent bodies in combination with the decomposition of amino acids during extended aqueous alteration.

Indigenous amino acids in primitive CR meteorites

“…This trend is clearly seen for the amino acid content in the CM group, as the total amino acid abundances decrease from the least aqueously altered (Chizmadia and Brearley 2003) CM2 Y-791198 (Shimoyama and Ogasawara 2002) to the more aqueously altered CM1s LAP 02277 (Fig. 3), ALH 88045, and MET 01070 (Botta et al 2007).…”

“…As CMs contain more than 50 vol% matrix (McSween 1979) and CRs about 30 vol% matrix (Weisberg et al 1993), this would imply that the amino acid matrixnormalized concentrations would be even higher in EET 92042 and GRA 95229 than in CMs. Figure 3a shows the total amino acid abundances (in ppb) for the CM2 Y-791198 (Shimoyama et al 1985;Shimoyama and Ogasawara 2002), the CM1 LAP 02277 (Botta et al 2007), the CR2s Renazzo , EET 92042, and GRA 95229 (Tables 1 and 2), and the CR1 GRO 95577 (Table 1) GRA 95229. This may indicate that these three meteorites had similar amino acid precursor material available.…”

“…3. a) Total amino acid abundances (in ppb) for the α-amino acids (glycine, alanine, α-ABA, α-AIB, isovaline and valine), β-amino acids β-alanine, β-ABA, and β-AIB), γ-amino acid (γ-ABA) and dioic amino acids (aspartic acid and glutamic acid) present in the CR2s GRA 95229 () and EET 92042 () (this work; data taken from Tables 1 and 2), the CM2 Y-791198 (Δ) (Shimoyama et al 1985;Shimoyama and Ogasawara 2002), the CR2 Renazzo (⎯) , the CR1 GRO 95577 (O) (this work; data taken from Table 1) and the CM1 LAP 02277 (*) (Botta et al 2007). Straight and branched carbon chain amino acids plotted by increasing carbon number, respectively.…”

“…Straight and branched carbon chain amino acids plotted by increasing carbon number, respectively. In the case of the Renazzo and LAP 02277 meteorites, not all amino acid abundances are available from the literature Botta et al 2007). The abundance of α-ABA was not determined for the GRO 95577 meteorite (this work, Table 1).…”

Polycyclic aromatic hydrocarbons and amino acids in meteorites and ice samples from LaPaz Icefield, Antarctica

“…All glassware was wrapped in Al foil and heated to 500 °C for at least 3 h before usage. These procedures have been used in previous studies of organic compounds in meteorites (e.g., Bada et al 1998;Glavin et al 2006;Botta et al 2007;Martins et al 2007aMartins et al , 2007b.…”