The fractionation of nickel between olivine and augite as a geothermometer

The coexisting olivine, clinopyroxene and glass of five samples collected from the Makaopuhi lava lake in Hawaii, at temperatures ranging from 1050 to 1160°C were analysed for nickel with an electron probe microanalyser. The results strongly suggest that the distribution of nickel between these three phase pairs well obeys the thermodynamic partition law, and that under favourable conditions, the distribution coefficients permit the estimation of the crystallisation temperature within an accuracy of 10–20°C.

It is concluded that the application of the Makaopuhi data to plutonic and to other volcanic rocks should be carried out with caution because the effect of pressure and the changing composition of the phases upon the numerical values of the distribution coefficients is not known quantitatively.