抄録
Trace element abundances, especially rare earth elements (REE) abundances, have been used to constrain high temperature processes, such as gas/solid or liquid/solid fractionations and redox conditions in the early solar system. I review some recent studies on trace element abundances in chondrules from unequilibrated chondritic meteorites and briefly describe a procedure for direct-loading isotope dilution mass spectrometry. Recently obtained precise REE data on chondrules in carbonaceous chondritic meteorites (CV3 Allende and CO3 Felix) clearly demonstrate the existence of REE fractionation among chondrules, suggesting that very high temperature gas/solid (or gas /liquid) processing must have occurred prior to chondrule-formation melting event in the early solar nebula. Based on trace element abundances in chondrules, chemical features of precursor material and their melting processes are discussed.
