Fate of Hydrous Fe-Rich Silicate Melt in Earth's Deep Mantle

Zhixue Du, Jie Deng, Yoshinori Miyazaki, Ho kwang Mao, Bijaya B. Karki, Kanani K.M. Lee

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

Density of silicate melt dictates melt migration and establishes the gross structure of Earth's interior. However, due to technical challenges, the melt density of relevant compositions is poorly known at deep mantle conditions. Particularly, water may be dissolved in such melts in large amounts and can potentially affect their density at extreme pressure and temperature conditions. Here we perform first-principles molecular dynamics simulations to evaluate the density of Fe-rich, eutectic-like silicate melt (E melt) with varying water content up to about 12 wt %. Our results show that water mixes nearly ideally with the nonvolatile component in silicate melt and can decrease the melt density significantly. They also suggest that hydrous melts can be gravitationally stable in the lowermost mantle given its likely high iron content, providing a mechanism to explain seismically slow and dense layers near the core-mantle boundary.

Original languageEnglish (US)
Pages (from-to)9466-9473
Number of pages8
JournalGeophysical Research Letters
Volume46
Issue number16
DOIs
StatePublished - Aug 28 2019
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Geophysics
  • General Earth and Planetary Sciences

Keywords

  • high pressure
  • lower mantle
  • magma ocean
  • melt density
  • molecular dynamics
  • water

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