Distribution of aliphatic amines in CO, CV, and CK carbonaceous chondrites and relation to mineralogy and processing history

Abstract

The analysis of water‐soluble organic compounds in meteorites provides valuable insights into the prebiotic synthesis of organic matter and the processes that occurred during the formation of the solar system. We investigated the concentration of aliphatic monoamines present in hot acid water extracts of the unaltered Antarctic carbonaceous chondrites, Dominion Range (DOM) 08006 (CO3) and Miller Range (MIL) 05013 (CO3), and the thermally altered meteorites, Allende (CV3), LAP 02206 (CV3), GRA 06101 (CV3), Allan Hills (ALH) 85002 (CK4), and EET 92002 (CK5). We have also reviewed and assessed the petrologic characteristics of the meteorites studied here to evaluate the effects of asteroidal processing on the abundance and molecular distributions of monoamines. The CO3, CV3, CK4, and CK5 meteorites studied here contain total concentrations of amines ranging from 1.2 to 4.0 nmol g−1 of meteorite; these amounts are 1–3 orders of magnitude below those observed in carbonaceous chondrites from the CI, CM, and CR groups. The low‐amine abundances for CV and CK chondrites may be related to their extensive degree of thermal metamorphism and/or to their low original amine content. Although the CO3 meteorites, DOM 08006 and MIL 05013, do not show signs of thermal and aqueous alteration, their monoamine contents are comparable to those observed in moderately/extensively thermally altered CV3, CK4, and CK5 carbonaceous chondrites. The low content of monoamines in pristine CO carbonaceous chondrites suggests that the initial amounts, and not asteroidal processes, play a dominant role in the content of monoamines in carbonaceous chondrites. The primary monoamines, methylamine, ethylamine, and n‐propylamine constitute the most abundant amines in the CO3, CV3, CK4, and CK5 meteorites studied here. Contrary to the predominance of n‐ω‐amino acid isomers in CO3 and thermally altered meteorites, there appears to be no preference for the larger n‐amines.

Molecular distribution, 13C‐isotope, and enantiomeric compositions of carbonaceous chondrite monocarboxylic acids

“…Our results on the abundance and molecular distribution of MCAs essentially follow the same overall trends as those observed previously for aliphatic amino acids and monoamines in chondrites: decreasing concentration with increasing molecular weight, and the total concentration of water-soluble MCAs, amino acids, and monoamines in the order of CR2 > CM2 > CM1/ 2 ≫ CO3 % CV3 % CK4-5 (e.g., Martins et al 2008;Glavin et al 2011;Burton et al 2012Burton et al , 2015Elsila et al 2016;Aponte et al 2017). These similarities may suggest that meteoritic MCAs, amino acids, and amines may have shared similar synthetic processes before the accretion of the parent body Pizzarello 1983, 1986;Huang et al 2005;Aponte et al 2011Aponte et al , 2016.…”

“…; Aponte et al. ). These similarities may suggest that meteoritic MCAs, amino acids, and amines may have shared similar synthetic processes before the accretion of the parent body (Cronin and Pizzarello , ; Huang et al.…”

“…Abundances of MCAs in hot-water extracts of the carbonaceous chondrites studied here (values taken from Table 2). Meteorite groups are arranged according to their aqueous and thermal alteration (Keller et al 2012;Alexander et al 2013Alexander et al , 2015Davidson et al 2015;Lee et al 2016;Aponte et al 2017). Table 3.…”

“…Table 3. Meteorite groups are arranged according to their aqueous and thermal alteration (Keller et al 2012;Alexander et al 2013Alexander et al , 2015Davidson et al 2015;Lee et al 2016;Aponte et al 2017 Alexander et al (2007Alexander et al ( , 2010Alexander et al ( , 2012Alexander et al ( , 2013Alexander et al ( , 2015; Davidson et al (2015).…”

“…Keller et al (2012);Alexander et al (2013Alexander et al ( , 2015;Lee et al (2016);Davidson et al (2015);Aponte et al (2017).b Further details about the classification of MIL 090001 are available in the supporting information. ALH = Allan Hills; LEW = Lewis Cliffs; LON = Lonewolf Nunataks; EET = Elephant Moraine; GRA = Graves Nunataks; LAP = La Paz Icefield; DOM = Dominion Range.…”