Fluorine and chlorine fractionation during magma ocean crystallization: Constraints on the origin of the non-chondritic F/Cl ratio of the Earth

Hideharu Kuwahara, Takanori Kagoshima, Ryoichi Nakada, Nobuhiro Ogawa, Asuka Yamaguchi, Yuji Sano, Tetsuo Irifune

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

Previous studies have reported that the relative abundances of volatile elements in the silicate Earth are non-chondritic. The abundance and distribution of volatile elements in terrestrial planets would have been predominantly controlled by planetary formation processes, including core-mantle separation, magma ocean crystallization, and volatility-dependent high-temperature fractionation. Thus, the current abundance patterns of volatile elements in the silicate fraction of terrestrial planets are the key to understanding the accretional history of terrestrial volatiles and the chemical differentiation of terrestrial planets. Although the origin of the non-chondritic ratios of volatile elements in terrestrial planets has been previously studied, it is still a matter of debate. In this study, we focused on the super-chondritic F/Cl ratio of the bulk silicate Earth and experimentally investigated the silicate mineral-melt partitioning of fluorine and chlorine at pressures from 18 GPa to 25 GPa. Our experimental results show that fluorine is moderately compatible with mantle minerals, whereas chlorine is highly incompatible. These results support the formation of a solid mantle with high F/Cl ratios, and a residual magma ocean and steam atmosphere with low F/Cl ratios during magma ocean crystallization. Thus, the F/Cl ratio in the residual solid parts of terrestrial planets would have become relatively enriched following escape of volatile elements from the planetary surface into outer space. This model is consistent with the collisional erosion hypothesis of primordial crusts and atmospheres, and current observations on the abundance and distribution of terrestrial fluorine and chlorine.

Original languageEnglish
Pages (from-to)241-249
Number of pages9
JournalEarth and Planetary Science Letters
Volume520
DOIs
Publication statusPublished - Aug 15 2019
Externally publishedYes

Keywords

  • chlorine
  • fluorine
  • magma ocean
  • partitioning
  • terrestrial planets

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

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