Zirconium and hafnium in meteorites by activation analysis

Abstract

Zirconium and hafnium have been determined in 28 chondrites and 7 achondritea by the use of thermal and 14 MeV neutron activation analyses. The distribution pattern of these elements in the three major classes of chondrites showed that the order of atomic abundances for both elements relative to silicon (Si = 10 6 atoms) was: carbonaceous chondrites > ordinary chondrites > enstatite chondrites. Average atomic abundances of 13 atoms Zr (Si = 10 6 atoms) and 0.19 atom Hf (Si = 10 6 atoms) were established for the chondrites. The calcium-rich achondrites were observed to be enriched in these elements relative to the chondrites while an opposite trend was noted for the calcium-poor achondrites. The average Zr Hf ratio on a weight basis for all the stony meteorites analyzed in this work was 43, a value which is in good agreement with that reported in the literature for the earth's crust. Based on this ratio, no significant fractionation of these elements between the earth and meteorites is implied.