Amino acid composition, petrology, geochemistry, C-14 terrestrial age and oxygen isotopes of the Shi∫r 033 CR chondrite

Martins, Z.; Hoffmann, B.A.; Gnos, E.; Greenwood, R.C.; Verchovsky, A.; Franchi, I.A.; Jull, A.J.T; Botta, O.; Glavin, D.P.; Dworkin, J.P. and Ehrenfreund, P. (2007). Amino acid composition, petrology, geochemistry, C-14 terrestrial age and oxygen isotopes of the Shi∫r 033 CR chondrite. Meteoritics and Planetary Science, 42(9) pp. 1581–1595.

URL: http://open.library.ingentaconnect.com/content/ari...

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 H2O 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.

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