Murray meteorite

Figure 7.6 Isotopic compositions of meteorite (Murray), solar, and terrestrial Xe, displayed as per mil variation of observed isotope ratios (normalized to 130Xe) in air and the carbonaceous chondrite Murray from the corresponding ratios SUCOR, a solar Xe composition calculated to be surface-correlated Xe in a lunar mare soil. The dashed line, illustrating linear fractionation, is primarily for reference. Reproduced from Podosek (1978).

Essentially the same amino acids, and nearly equal quantities of D and L enantiomers, were detected in the Murray meteorite, another type II carbonaceous chondrite [6]. Recent expeditions to Antarctica have returned with a large number of meteorites, many of which are carbonaceous chondrites. These may have been protected from terrestrial contamination by the pristine Antarctic ice. Careful analysis of two of these, the Yamato (74662) and the Allan Hills (77306), both type II carbonaceous chondrites, by ion exchange chromatography, gas chromatography, and GC/MS, have detected a wide variety of both protein and non-protein amino acids in approximately equal D and L abundances [9,10]. Fifteen amino acids were detected in the Yamato meteorite and twenty in the Allan Hills, the most abundant being glycine and alanine. The amino acid content of the Yamato meteorite is comparable with that of the Murchison and Murray, but the Allan Hills contains 1/5 to 1/10 that quantity. Unlike earlier meteorites from other locations, the quantities of amino acids in the exterior and interior portions of the Yamato and Allan Hills meteorites are almost identical [9,10]. Thus, these samples may have been preserved without contamination since their fall in the blue ice of Antarctica, which js 250,000 years old in the region of collection. 

Hydroxypyrimidines have been detected in the Murchison, Murray, and Orgueil carbonaceous chondrites in abundances similar to those of amino acids [7]. Earlier analyses of the Orgueil meteorite By thin layer chromatography of organic extracts indicated the presence of melamine, ammeline, adenine, and guanine [8]. Although these could not be confirmed by Folsome, et al., [7] using GC/MS, recent studies by Schwartz [11] and by Hayatsu, et al., [12] have shown that these constituents of the nucleic acids may indeed exist in the carbonaceous chondrites. 

Titanium-calcium. The first evidence for isotopic anomalies in the iron-group was found in Ti showing up to 10% excesses of Ti in hibonites from the Murray CM2 meteorite (Hutcheon et al. 1983 Fahey et al. 1985 Ireland et al. 1985 Hinton et al. 1987). Further studies in Murchison showed that Ti extended from -7% to +27% associated with Ca variation from -6% to +10% (Ireland 1988 Ireland 1990). Except for the magnitude of the variations, this is similar to the results from Allende inclusions. Only a few samples display mass-dependent fractionation for which it ranges up to 1.3 %/amu. In the majority of the samples, it is absent or very low (less than 1 %o/amu) for Ca-Ti. There is no correlation between the presence of linear fractionation and the magnitude of Ti effects. Ti variations are also present, but about an order of magnitude smaller than Ti. Variations affecting these two isotopes are related but not strictly correlated (Ireland 1988). 

Virag A, Zinner E, Lewis RS, Tang M (1989) Isotopic compositions of H, C, and N in C8 diamonds from the Allende and Murray carbonaceous chondrites. Lunar Planet Sci XX 1158-1159 Volkening J, Papanastassiou DA (1989) Iron isotope anomalies. Astrophys J 347 L43-L46 Volkening J, Papanastassiou DA (1990) Zinc isotope anomalies. Astrophys J 358 L29-L32 Wadhwa M, Zinner EK, Crozaz G (1997) Manganese-chromium systematics in sulfides of unequilibrated enstatite chondrites. Meteorit Planet Sci 32 281-292... 

Zitmer E (1997) Presolar material in meteorites an overview. In Astrophysical Implications of the I aboratory Study of Presolar Materials. Bematowicz TJ and Zinner E (eds) AIP, New York, p 3-26 Zinner EK, Gopel C (2002) Aluminium-26 in H4 chondrites implications for its production and its usefulness as a fine-scale chronometer for early solar system events. Meteorit Planet Sci 37 1001-1013 Zinner E, Amari S, Guitmess R, Nguyen A, Stadermann FJ, Walker RM, I wis RS (2003) Presolar spinel grains from the Murray and Murchison carbonaceous chondrites. Geochim Cosmochim Acta 67 5083-5095... 

The Allende, Murchison, Murray and Orgueil meteorites are particularly highly prized for research into stellar grains, since several kilograms of this material have been identified in each of them. This is sufficient to be able to take samples of the order of 1 g without damaging the source. Such samples can then be subjected to compositional analysis. But how can we extract these stellar jewels, measuring at most 1 /rm in diameter, from the matrix in which they are embedded The best way of finding a needle in a haystack is to bum the hay. Cosmochemists employ basically the same method when they use chemical processes to isolate star dust trapped in meteoritic stone. They may then analyse... 

It was mentioned earher that many molecules can be formed in cosmic space before arriving on Earth. What about chiral compounds We know that amino acids are present in meteorites (Epstein et al., 1987 Pizzarello etal., 1994 Pizzarello and Cronin, 2000 Pizzarello and Weber, 2004). In this regard, of particular interest is the report on a-methyl amino acids, which have been found in L-enantiomeric excess in Murchison and Murray meteorites (Cronin and Pizzarello, 1997). These compounds are particularly resistant to racemization, and it is perhaps because of this that chirality has been preserved. It is not simple to assess whether these chiral exogenous compounds were the seeds for homochirahty of life on Earth (Bada, 1997). 

Pizzarello, S. and Cronin, J. R. (2000). Non-racemic amino acids in the Murray and Murchison meteorites. Geochim. Cosmochim. Acta, 64, 329-38. 

Yuen, G. U. and Knenvolden, K. A. (1973). Monocarboxylic acids in Murray and Murchison carbonaceous meteorites. Nature, 246, 301-2. 

Bematowicz, T., Fraundorf, G., Tang, M., Anders, E., Wopenka, B., Zinner, E. Fraundorf, P. 1987 Evidence for interstellar SiC in the Murray carbonaceous meteorite. Nature, Lond. 330, 728 730. 

We analyzed several organic and inorganic phases identified from the Murchison and Murray meteorites [100] in order to determine whether they contain any possible chirality besides the enantiomeric amino acids [98]. Asymmetric autocatalysis is a method capable of revealing chiral imbalances in various media, therefore, we employed this method as a possible chiral sensor for the meteorites. 

TABLE 7.1 Enantiomeric Enrichments for Amino Acids in the Murchison and Murray Meteorites... 

The indigenous nature of the alkanes in at least the Murray, Murchison, and Orgueil meteorites (Studier et al., 1968, 1972) is supported by 4 lines of evidence,... 

Rubin A. E. and Wasson J. T. (1986) Chondrules in the Murray CM2 meteorite and compositional differences between CM-CO and ordinary chondrite chondrules. Geochim. Cosmochim. Acta 50, 307-315. 

Hanowski N. P. and Brearley A. J. (2000) Iron-rich aureoles in the CM carbonaceous chondrites, Murray, Murchison, and Allan Hills 81002 evidence for in situ aqueous alteration. Meteorit. Planet. Sci. 35, 1291-1308. 

The majority of the carbon in the Murchison macromolecular material is present within aromatic ring systems. This aromatic nature has been revealed by a series of pyrolysis studies of meteorites such as OrgueU (CIl), Murchison (CM2), Murray (CM2), and Allende (CV3) in which the macromolecular material was thermally fragmented to produce benzene, toluene, alkyl-benzenes, naphthalene, alkylnaphthalenes, and PAHs with molecular weights up to around 200-300 amu (Simmonds et al, 1969 Studier et al, 1972 Levy et al, 1973 Bandurski and Nagy, 1976 Holtzer and Oro, 1977 Murae, 1995 Kitajima et al, 2002). Further identification of the aromatic units in the Murchison macromolecular material was achieved by Hayatsu et al (1977),... 

Degens E. T. and Bajor M. (1962) Amino acids and sugars in the Brudeheim and Murray meteorites. Naturwiss. 49, 605-606. 

Earth s mantle must have occurred very early in the history of the solar system. Eigure 17 plots Cr/ Cr versus Mn/ Cr ratios of several chondritic meteorites and samples of differentiated planets. The data are taken from the work of Lugmair and Shukolyukov (1998) and Shukolyukov and Lugmair (2000, 2001). Samples from the metal-rich CH-chondrite HH237, the Earth, Allende (CV), Murray (CM), and Orgueil (Cl) define an approximately straight line in Eigure 17. If this line is interpreted as an isochron. 

University of Texas scientists Robert Folk and F. Leo Lynch also announced the observation of fossils of terrestrial nanobacteria in another carbonaceous chondrite meteorite named the Allende meteorite. Other research has demonstrated that the Murchison and Murray meteorites... 

---