Oxygen element abundances

Some carbonaceous chondrites are rich in carbon (Cl and CM chondrites have 1.5-6% carbon), but others are not. Carbonaceous chondrites are now defined on the basis of their refractory elemental abundances, which equal or exceed those in Cl chondrites. Carbonaceous chondrites are derived from very diverse asteroids, which probably formed in very different locations. The parent bodies of Cl and CM chondrites are highly altered, yet the parent bodies of CH and CB chondrites are less altered than all other chondrite bodies. Young et al (1999) infer from oxygen isotopic compositional data that Cl, CM, and CV chondrites could have been derived from different zones in a single, aqueously altered body. However, bulk chemical differences between these groups indicate fractionation during nebular processes, not aqueous alteration (see below), and the components in CM and CV chondrites are quite different. 

---