Affiliation:
1. Institute of Geology of Ore Deposits, Petrography, Mineralogy, and Geochemistry, Russian Academy of Sciences
Abstract
Knowledge of mineral–melt partition coefficients (D) is necessary for geochemical modeling of magma formation and evolution. The main source of these parameters is experiments on equilibrium between minerals and silicate melt. The database on mineral–melt equilibrium experiments has grown continuously, which allows one to refine partition coefficients and reveal the most important factors affecting them. This paper reports the analysis of available experimental data on trace element partitioning between olivine and melt (7000 experiments from 587 publications were used). Based on the statistical processing of the data array, the dependence of D on melt and olivine composition and P–T conditions was evaluated. It was found that most of incompatible elements are either insensitive or moderately sensitive to these parameters. Among the compositional parameters, CaO content in melt is most significant. It was shown that D estimates can be significantly improved by using ratios of D values for different elements. Such ratios are often independent of experimental parameters and much less variable than D values for particular elements. The obtained D estimates for basaltic compositions vary within six orders of magnitude, from 10–5 (U, Th, and La) to ~5–10 (Co and Ni). The low D values for most elements (0.1) indicate that many trace element ratios in melts do not change significantly even at high degrees of olivine crystallization. The obtained estimates were compared with data on element partitioning between high-pressure (Mg,Fe)2SiO4 phases (wadsleyite and ringwoodite) and silicate melt and between olivine and carbonate–silicate melts. In both cases, there is a close similarity to element partitioning between olivine and silicate melt. One exception is REE. DREE values for the wadsleyite/ringwoodite–melt and olivine–carbonate melt systems are approximately one order of magnitude lower than those for olivine–silicate melt partitioning.
Publisher
The Russian Academy of Sciences
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