Meteorites sulphur isotopes

Recent work by Wilson Orr ( ) and others using stable isotope techniques has provided strong evidence that incorporation from an inorganic source is the most probable explanation. Inorganic sulphur (sulphate) tends to be richer in the heavy sulphur isotope, compared with reference meteoritic sulphur... 

Farquhar J., Savarino J., Jackson T. L., and Thiemens M. H. (2000) Evidence of atmospheric sulphur in the martian regolith from sulphur isotopes in meteorites. Nature 404, 50-52. 

Shima, M., Gross, W.H. and Thode, H.G., 1963. Sulphur isotope abundances in basic sills, differentiated granites and meteorites. J. Geophys. Res., 68 2835—2847. 

The sulphur isotopic ratio, 34S/32S, expressed as 834S (in parts per thousand, %o, relative to meteoritic sulphur) of ocean water has changed through time, and is reasonably well known for the past 900 Myr (Holser and Kaplan, 1966 Claypool et al., 1980 Strauss, 1997). Accordingly, older marine (and therefore, by default, also some terrestrial) evaporites may be... 

For stable sulphur isotopes, the standard is an iron sulphide mineral (troilite) from the Canyon Diablo meteorite. It is known as CDT (Canyon Diablo troilite) and equation 1 becomes ... 

Isotopic composition of sulphur S is determined usually by the ratio (4 stable isotopes - S, and - are known). This ratio is most stable in meteorites. That is why as standard is used the sulphur isotopic composition in troilite (FeS) from the meteorite in the Canyon Diablo Troilite (CDT) where the ratio is 1/22.22. 

---