PRECISE MEASUREMENT OF ZIRCONIUM ISOTOPES BY THERMAL IONIZATION MASS-SPECTROMETRY

An analytical method for high-precision measurement of zirconium isoto pe ratios using a Sector thermal ionization mass spectrometer (TIMS) i s reported. The chemical separation procedure of Zr has been refined b y employing a small anion exchange resin column to minimize the Mo int erference on Zr-92, Zr-94 and Zr-96. TO confirm the reproducibility of this technique, Zr isotope analyses from six commercially available c hemical samples and from two meteorites were carried out. Isotopic rat ios were corrected for mass fractionation by normalization with the Zr -94/Zr-90 ratio. The determined ratios 91/90, 92/90 and 96/90 were wit hin the precision range 0.002 to 0.007% (relative standard deviations) . The data indicate the existence of zirconium isotopic heterogeneity in the earth and the possibility of pre-terrestrially printed and terr estrially conserved isotope aberration patterns of zirconium is discus sed. (C) 1997 Elsevier Science B.V.