A CONSISTENT PARTITION-COEFFICIENT SET FOR CLINOPYROXENE, AMPHIBOLE AND GARNET FROM LASER-ABLATION MICROPROBE ANALYSIS OF GARNET PYROXENITES FROM KAKANUI, NEW-ZEALAND

The abundances of 24 trace elements in clinopyroxene, amphibole and ga r net from 4 garnet pyroxenites from Kakanui, New Zealand, were obtain ed by laser ablation microprobe (LAM). Since equilibrium conditions ca n be proven, the data are evaluated for their use of calculating relia ble and consistent partition coefficients between minerals and melt. U sing the experimentally determined D-CPX/L values of HART & DUNN (1993 ) as a reference set, D-AMP/L and D-GRT/L were calculated using the me asured D-AMP/CPX and D-GRT/CPX data from Kakanui. The overall D-AMP/L pattern calculated from the Kakanui data is consistent with published experimental data. We recommend the calculated D-AMP/L values for mult i-element modelling in mafic and ultramafic systems since they represe nt an extensive data set for D-AMP/L and include reliable D-AMP/L for SC (0.74) and V (3.0). The D-GRT/L values from this study differ from experimentally derived D-GRT/L since values for highly incompatible el ements are significantly higher in the experimental data sets. This di fference is interpreted in terms of a strong structurally-controlled t emperature effect on partitioning behaviour. The 920 degrees C Kakanui data set may be more applicable to many natural crystallization condi tions than experimental data sets at 1400 degrees C.