Amino acid composition, petrology, geochemistry, ¹⁴C terrestrial age and oxygen isotopes of the Shişr 033 CR chondrite

Abstract

Abstract-We have analyzed Shi∫r 033, a CR chondrite from the Omani desert, using several different analytical techniques designed to study the degree of terrestrial alteration of this meteorite and also its petrologic classification. Bulk chemical analyses (including organic carbon and mean total H 2 O content) are consistent with a CR classification. Additionally, oxygen isotope analysis on a bulk sample indicates that Shi∫r 033 is of type CR2. Amino acid analysis using liquid chromatography with UV fluorescence detection (HPLC-FD) and liquid chromatography-time of flight-mass spectrometry (LC-ToF-MS) show that the absolute and the relative amino acid content of Shi∫r 033 is distinct from other carbonaceous chondrites. Oxygen isotope analysis of a phyllosilicate-rich dark inclusion shows that this inclusion is closer to CV3 or CO3 chondrites. The effects of terrestrial weathering in Shi∫r 033 are evident from the dark inclusion carbon isotopic data, bulk chemistry (through the elevated concentrations of Sr and Ba), and amino acid data, which suggests extensive amino acid contamination of the meteorite from the fall site soil. Nevertheless, Shi∫r 033 contains a small fraction of indigenous components, as indicated by the presence of the extraterrestrial amino acid α-aminoisobutyric acid (AIB) that was not detected in the Shi∫r soils. Finally, the terrestrial age of Shi∫r 033 was determined and is discussed in the context of high levels of contamination.

Which Amino Acids Should Be Used in Prebiotic Chemistry Studies?

“…Kminek et al (2002) 2007; Martins et al 2007a;Martins et al 2007b). As we can see for the Murchison meteorite, the analysis of amino acids in meteorites is not easily achieved, since a wide range of concentrations was found (Table 2).…”

Oxygen isotope variation in primitive achondrites: The influence of primordial, asteroidal and terrestrial processes

“…In this investigation, a high proportion of the samples studied have been leached, using a solution of ethanolamine thioglycollate (EATG) (Cornish and Doyle, 1984;Martins et al, 2007). Tests undertaken on a suite of variably weathered H chondrites collected in the Tenere region of Niger indicated that the EATG-wash method was efficient at removing Fe-rich alteration products, without disturbing the primary oxygen isotope composition of the samples (Martins et al, 2007). EATG treatment is preferred to conventional leaching in dilute HCl, as this latter method can partially remove indigenous glass and feldspathic-rich material.…”

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.…”

“…For the amino acid analyses, approximately 100 mg of each powdered meteorite sample was analyzed using the established procedure (Zhao and Bada 1995;Botta and Bada 2002a;Martins et al 2007b) for extracting and analyzing amino acids in meteorites, which includes each sample being flame sealed in a test tube with 1 ml of HPLC grade water and boiled for 24 h. in a heating block at a temperature of 100 °C. One of two equal parts of the supernatants was then subjected to a 6 N HCl acid vapor hydrolysis for 3 h at 150 °C.…”