Refractory element variations in chondritic meteorites. It is widely held that the Earth's composition matches that of chondritic meteorites for refractory elements. However, new data for the concentrations of highly refractory elements have demonstrated that significant variation in refractory element ratios exists within the chondritic meteorite groups. In particular, the Nb/Ta ratio in CV chondrites is lower than that of most other chondrite types. Münker et al. (2003, Science) have attributed this to the presence of Ta-rich calcium-aluminum inclusions (CAI's) in CV's. This project would test this hypothesis by measuring the refractory element compositions of CAIs as well as chondrules using the laser ablation ICP-MS.

Supervisors: Bill McDonough, Roberta Rudnick, Richard Walker, Richard Ash