Confidence Limits for Silicate Perovskite Equations of State

We examine thermoelastic equations of state for silicate perovskite based on data from recent static compressiori studies. We analyze trade-offs among the fitting parameters arid examine data sets for possible effects of metastability and of Mg-Fe solid solution. Significant differences are found between equations of' state based on low pressure measurements obtained for perovskite outside of its stability field. I~icreasingly consistent results are obtained when higller pressure data are used, despite differences in the zero-pressure pararneters used to describe the equa t io~~s of state. The results highligllt the inlportance of measuring the thermoelastic properties of perovskite at high pressure, specifically within its stability field, and the potential problerns associated with large extrapolatioris of equations of state in the analysis of seismic data.