ABUNDANCES OF TITANIUM, ZIRCONIUM AND HAFNIUM IN STONY METEORITES

The concentrations of Ti, Zr and Hf have been determined, by a stable isotope dilution method, in 27 chondrites, seven achondrites and standard rock samples BCR-1 and W-1. Among all chondrites investigated, enstatite chondrite Abee is lowest in Ti atomic ratio compared with Si while all carbonaceous chondrites show higher values. The Zr contents are higher in CII and CIII chondrites, relative to the other groups of chondrites. There is a clustering of Ti and Zr within each group. The Zr Hf ratios in CII, CIII. E and H chondrites are essentially the same, while that in the CI chondrite is lower and in L, LL and unequilibrated chondrites are higher. The concentrations of Ti, Zr, Hf and Ti Zr, Zr Hf ratios in achondrites are variable, even among members of the same group. Based on these results, condensation models for these elements are discussed. The variable results for Ti, Zr and Hf in achondrites may be due to the reheating recrystallization and metamorphic processes. 'Cosmic atomic abundances' of Ti, Zr and Hf are calculated as 2470, 11.2 and 0.185. respectively for Si = 106 atoms. © 1979.