Equation of state for silicate melts: A comparison between static and shock compression

The density data of silicate melts reported by static and shock compression have been compared quantitatively at the pressure condition of the Earth's deep upper mantle. The equation of state based on the static compression data cannot explain the shock compression data, and the systematic differences between them have been revealed. The shock temperatures were estimated with different methods among papers, and the reported values differed considerably from one another. The shock temperatures estimated by assuming phase‐transition‐like structural changes in melts lie between the previous estimates. Many of them are well below the liquidus temperatures of each sample, suggesting that the sample state may have been altered during the shock compression. In addition, some of the shock compression data reanalyzed in the recent paper differ considerably from the original. These results suggest that silicate melts show phase‐transition‐like structural changes at high pressures, which are consistent with the static compression data. Key Points Discrepancies are found in silicate melt density by static and shock compression Reestimated temperatures of shock data are well below liquidus temperatures Silicate melts show phase‐transition‐like structural changes at high pressures