The preservation state of organic matter in meteorites from Antarctica

Sephton, M. A.; Bland, P. A.; Pillinger, C. T.; Gilmour, I.

doi:10.1111/j.1945-5100.2004.tb00116.x

Cited by 32 publications

(31 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Among the potential degradation/removal processes, oxidation may have been an important mechanism early in the aqueous alteration history (Cody and Alexander 2005). During aqueous alteration, low-temperature chemical oxidation would have increasingly removed the aliphatic moieties in the free and macromolecular matter (Sephton et al 2004;Cody and Alexander 2005;Martins et al 2006). 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.…”

Section: Causes Of Amino Acid Abundance Variation Between Meteoritesmentioning

confidence: 99%

Indigenous amino acids in primitive CR meteorites

Martins

Alexander

Orzechowska

et al. 2007

Meteorit & Planetary Scien

146

173

View full text Add to dashboard Cite

Abstract-CR chondrites are among the most primitive meteorites. In this paper, we report the first measurements of amino acids in Antarctic CR meteorites. Three CRs, Elephant Moraine (EET) 92042, Graves Nunataks (GRA) 95229, and Grosvenor Mountains (GRO) 95577, were analyzed for their amino acid content using high-performance liquid chromatography with UV fluorescence detection (HPLC-FD) and gas chromatography-mass spectrometry (GC-MS). Our data show that EET 92042 and GRA 95229 are the most amino acid-rich chondrites ever analyzed, with total amino acid concentrations ranging from 180 ppm to 249 ppm. The most abundant amino acids present in the EET 92042 and GRA 95229 meteorites are the α-amino acids glycine, isovaline, α-aminoisobutyric acid (α-AIB), and alanine, with δ 13 C values ranging from +31.6‰ to +50.5‰. The carbon isotope results together with racemic enantiomeric ratios determined for most amino acids strongly indicate an extraterrestrial origin for these compounds. Compared to Elephant Moraine (EET) 92042 and GRA 95229, the more aqueously altered GRO 95577 is depleted in amino acids. In both CRs and CMs, the absolute amino acid abundances appear to be related to the degree of aqueous alteration in their parent bodies. In addition, the relative abundances of α-AIB and β-alanine in the Antarctic CRs also appear to depend on the degree of aqueous alteration.

show abstract

Section: Causes Of Amino Acid Abundance Variation Between Meteoritesmentioning

confidence: 99%

Indigenous amino acids in primitive CR meteorites

Martins

Alexander

Orzechowska

et al. 2007

Meteorit & Planetary Scien

146

173

View full text Add to dashboard Cite

show abstract

“…The cause of heterogeneities in C and N abundances and isotopic composition can be further explored through a comparison between meteorite falls and finds, since the chemistry of meteorite finds may be readily influenced by terrestrial weathering processes (Sephton et al 2004a). However, statistical comparisons are severely hindered by the relatively small size of the finds data set.…”

Section: Intrameteorite Heterogeneitymentioning

confidence: 99%

“…The trends observed in our data and in the published data suggest that with increasing alteration (in this case aqueous processing), 13 C-and 15 N-rich components are removed from the chondrites, resulting in an accompanying decrease in N abundance. Sephton et al (2004aSephton et al ( , 2004b have suggested that 13 C-and 15 N-rich organic species may become liberated from the organic macromolecular material during asteroidal hydrous processing. These components were proposed to contribute to the soluble organic fraction.…”

Section: Bulk Trends Within Groupsmentioning

confidence: 99%

Carbon and nitrogen in carbonaceous chondrites: Elemental abundances and stable isotopic compositions

Pearson

Sephton

Franchi

et al. 2006

Meteoritics &Amp; Planetary Science

Self Cite

174

143

View full text Add to dashboard Cite

Abstract-We have undertaken a comprehensive study of carbon and nitrogen elemental abundances and isotopic compositions of bulk carbonaceous chondrites. A strategy of multiple analyses has enabled the investigation of hitherto unconstrained small-scale heterogeneities. No systematic differences are observed between meteorite falls and finds, suggesting that terrestrial processing has a minimal effect on bulk carbon and nitrogen chemistry. The changes in elemental abundance and isotopic composition over the petrologic range may reflect variations in primary accreted materials, but strong evidence exists of the alteration of components during secondary thermal and aqueous processing. These changes are reflected within the CM2 and CO3 groups and follow the published alteration scales for those groups. The nitrogen isotope system appears to be controlled by an organic host, which loses a 15 N-rich component with progressive alteration. This study recommends caution, however, over the use of bulk carbon and nitrogen information for classification purposes; variance in relative abundance of different components in carbonaceous chondrites is significant and reflects intrameteorite heterogeneities.

show abstract

“…The weathering effects on organic materials during residence in Antarctic ice (Tyra et al, 2007) are not yet well understood. Sephton et al (2004) suggested that Antarctic weathering may have similar effects as the parent body aqueous alteration by removing ether bonds from organic material and alkyl side chains from its constituent units (Sephton et al, 2004).…”

Section: Raman Spectroscopymentioning

confidence: 99%

“…Sephton et al (2004) reported that the presence and amount of organic matter from carbonaceous chondrites in Antarctica are strongly associated with Antarctic weathering. Therefore, the effects of weathering should also be evaluated together with the characterization of organic components in AMMs.…”

Section: Introductionmentioning

confidence: 99%

Micro-spectroscopic characterization of organic and hydrous components in weathered Antarctic micrometeorites

et al. 2010

View full text Add to dashboard Cite

Eight unmelted Antarctic micrometeorite (AMMs) recovered from Kuwagata Nunatak were studied on Al-foils by infrared (IR), Raman, and visible reflection micro-spectroscopy in combination with electron microscopy. Major element abundances of the AMMs studied were found to be similar to solar abundance, although all have the common characteristic of Mg-depletion. Absorption bands around 500 nm were detected for some of the AMMs by the visible micro-spectroscopic method, and these AMMs can be assigned to Fe-hydroxidelike materials. These results suggest that the studied AMMs experienced weathering in Antarctica. Four grains showed the presence of IR H 2 O and CH bands similar to those of type 2 carbonaceous chondrites, while these were found to be absent in two grains, as in type 3 carbonaceous chondrites. D (disordered: 1360 cm −1 ) and G (graphite: 1600 cm −1 ) Raman band features of graphitic carbonaceous materials in these AMMs were not similar to those for type 3 but were rather close to those for type 2 and 1 carbonaceous chondrites, although some data showed a degree of deviation. The genetic classification of individual AMM grains can thus be studied by these methods, although the weathering effects and the atmospheric entry heating on organics and hydrous components need to be evaluated. These multiple micro-spectroscopic reflectance methods are useful for the characterization of precious small samples.

show abstract

The preservation state of organic matter in meteorites from Antarctica

Cited by 32 publications

References 13 publications

Indigenous amino acids in primitive CR meteorites

Indigenous amino acids in primitive CR meteorites

Carbon and nitrogen in carbonaceous chondrites: Elemental abundances and stable isotopic compositions

Micro-spectroscopic characterization of organic and hydrous components in weathered Antarctic micrometeorites

Contact Info

Product

Resources

About