TRACE-ELEMENT AND ISOTOPIC COMPOSITION OF BADDELEYITE

Baddeleyite from Palabora Igneous Complex, South Africa, is among the purest natural ZrO2 phases. This has been demonstrated by using variou s methods, i.e. microprobe, neutron activation, spark source and therm al ion mass spectrometry. HfO2 with 1.87% is the only other major comp onent. The concentrations of other HFSE are also relatively high, comp ared to most other elements, that reach only a few ppm. The REE displa y a U-shaped pattern that is interpreted to be superimposed by a stron gly LREE enriched source component. The high Sr-87/Sr-86 initial of 0. 713085 and the negative epsilon Nd-t of -10.7 prove that this componen t was LILE enriched for a long time prior to the formation of the Pala bora Igneous Complex. These data indicate that the baddeleyite crystal lized from a magma which was derived from an enriched mantle reservoir , similar to that involved in the formation of group II kimberlites.