Sulfur, meteorite evidence

There are good reasons to assume that the core contains some amount of carbon, phosphorus, and sulfur. These three elements are among the 12 most common in the Earth that account for >99% of the total mass (Table 5), as based on geochemical, cosmochemical, and meteoritical evidence. Seven out of 12 of these elements (not including carbon, phosphorus, and sulfur) are either refractory or major component elements. 

Farquhar J., Jackson T. L., and Thiemens M. H. (2000) A S-33 enrichment in ureihte meteorites evidence for a nebular sulfur component. Geochim. Cosmochim. Acta 64(10), 1819-1825. 

Kerridge JF (1983) Isotopic composition of carbonaceous-chondrite kerogen evidence for an interstellar origin of organic matter in meteorites. Earth Planet Sci Lett 64 186-200 Kerridge JF, Haymon RM, Kastner M (1983) Sulfur isotope systematics at the 21°N site. East Pacific Rise. Earth Planet Sci Lett 66 91-100... 

Tomascak PB, Ryan JG, Defant MJ (2000) Lithium isotope evidence for light element decoupling in the Panama subarc mantle. Geology 28 507-510 Tomascak PB, Widom E, Benton LD, Goldstein SL, Ryan JG (2002) The control of lithium budgets in island arcs. Earth Planet Sci Lett 196 227-238 Tomaszak PB (2004). Lithium isotopes in earth and planetary sciences. Rev Miner Geochem Trofimov A (1949) Isotopic constitution of sulfur in meteorites and in terrestrial objects. Doki Akad Nauk SSSR 66 181... 

Sulfur isotopes also show mass-independent effects that are probably produced by the same photochemical mechanism as oxygen effects in the Earth s upper atmosphere. Mass independent variations in sulfur from Martian meteorites have been interpreted to result from volcanic injections of SO2 and H2S into the Martian atmosphere followed by photolysis, which fractionates the sulfur isotopes. There is also evidence from ancient terrestrial sediments that the same photo lytic process was operating on sulfur in the Earth s atmosphere prior to 2.4 Ga, before oxygen began to accumulate in the atmosphere (see review by Thiemens, 2006). 

Silicates provide further evidence for the unusual origin of lAB-IIICD. While differentiated silicates might be expected in association with iron meteorites, silicates in lAB-IIICD irons are broadly chondritic (Mittlefehldt et al., 1998 Benedix et al., 2000 see Chapter 1.11). Models for the origins of lAB-IIICD iron meteorites include crystallization of a sulfur- and carbon-rich core in a partially differentiated object (Kracher, 1985 McCoy et al., 1993), breakup and reassembly of a partially differentiated object at its peak temperature (Benedix et al., 2000), or crystal segregation in isolated impact melt pools on the surface of a porous chondritic body (Wasson and Kallemeyn, 2002). A recent compilation of the chemical compositions of lAB and IIICD iron meteorites may be found in Wasson and KaUemeyn (2002). 

Farquhar J, Savarino J, Jackson TL, Thiemens MH (2000b) Evidence of atmospheric sulphur in the martian regolith from sulphur isotopes in meteorites. Nature 404 50-52 Finster K, Liesack W, Thamdrap B (1998) Elemental sulfur and thiosulfate disproportionation by desulfocapsa sulfoexigens sp.nov., a new anaerobic bacterium isolated from marine surface sediment. Appl Environ Microbiol 64 119-125... 

Fig. 4. The quantity of meteorite-derived sulfur, Sm, in the samples illustrated in Fig. 3, as a function of nitrogen content. Values of Sm were calculated from observed sulfur contents using a model based on mixing of indigenous and meteoritic sulfur followed by isotopically competitive loss of sulfur from the lunar surface, see text. Nitrogen content is employed here as a surrogate for soil maturity, see for example, Kerridge (1993). The clear correlation of Sm with maturity constitutes evidence for addition of meteoritic sulfur to the lunar regolith. From Kerridge et al (1975).

Nothing published since 1975 calls into question our model invoking influx of meteoritic sulfur and isotopically competitive loss of part of the resulting sulfur population. Curiously, a paper appeared shortly afterwards purporting to show, without benefit of isotopic data, that the lunar regolith contained meteoritic sulfur, but without the isotopic evidence for the substantial amount of missing sulfur, it represented an exercise in futility. Our model remains the best available description of the behavior of sulfur on the lunar surface, with the caveat that it is still... 

Kerridge J. F., Kaplan I. R. and Petrowski C. (1975) Evidence for meteoritic sulfur in the lunar regolith. Proc. Lunar Sci. Cortf. 6, 2151-2162. 

The evidence that stony meteorites collected in Antarctica are weathered implies that certain chemical elements are mobilized within the affected meteorite specimens. In addition, glacial meltwater and atmospheric carbon dioxide invade the affected meteorite specimens together with halogens, sulfur-bearing componnds, and organic molecules. Therefore, meteorites that fell on the East Antarctic ice sheet are altered mineralogically as well as chemically and, for that reason, their trace-element concentrations may differ from those of non-Antarctic meteorite falls. 

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