ABSTRACT
A considerable number of experiments have been done on the partitioning of Fe and Mg between coexisting silicates and many important geothermometers have thus been established. Nevertheless, little has been reported on the partitioning of Fe and Mn between silicate phases. This paper studies the influence of water on the partitioning of elements at 2.0, 4.0 GPa and 1200–1400°C. The research results show that the composition can cause the variation of lnKD, the addition of water in small amounts into the experimental system would also lead to the obvious increase of lnKD. But when the content of water in the system is increased, lnKD will decrease correspondingly. This indicates that the influence of water on the partitioning of Fe and Mg between olivine and orthopyroxene does not show a simple positive correlation. Experiments demonstrated that when a certain amount of water is present in the system, lnKD will increase with increasing pressure; lnKD still shows a linear correlation with l/T. Therefore, a geothermometer can be established on the partitioning coefficients of Fe and Mg for olivine and orthopyroxene.
