Excess O-16 Defines Six Types of Meteorites/Planets
Excess O-16 distinguishes six categories of meteorites and planets [Clayton et al., Earth Planet. Sci. Lett. 30 (1976) 10-18]. Debris from different stellar regions, with characteristic chemicals and isotopes (including O-16), condensed into the solids that make up meteorites and planets before mixing. The 45° line shows the addition of mono-isotopic O-16. On the other hand when oxygen isotopes in a given meteorite category are altered by mass-dependent fractionation, the isotope ratios lie along a 22.5° line.