Primordial metallic melt in the deep mantle

Zhou Zhang, Susannah M. Dorfman, Jabrane Labidi, Shuai Zhang, Mingming Li, Michael Manga, Lars Stixrude, William F. McDonough, Quentin Williams

Research output: Contribution to journalArticle

25 Scopus citations

Abstract

Seismic tomography models reveal two large low shear velocity provinces (LLSVPs) that identify large-scale variations in temperature and composition in the deep mantle. Other characteristics include elevated density, elevated bulk sound speed, and sharp boundaries. We show that properties of LLSVPs can be explained by the presence of small quantities (0.3-3%) of suspended, dense Fe-Ni-S liquid. Trapping of metallic liquid is demonstrated to be likely during the crystallization of a dense basal magma ocean, and retention of such melts is consistent with currently available experimental constraints. Calculated seismic velocities and densities of lower mantle material containing low-abundance metallic liquids match the observed LLSVP properties. Small quantities of metallic liquids trapped at depth provide a natural explanation for primitive noble gas signatures in plume-related magmas. Our model hence provides a mechanism for generating large-scale chemical heterogeneities in Earth's early history and makes clear predictions for future tests of our hypothesis.

Original languageEnglish (US)
Pages (from-to)3693-3699
Number of pages7
JournalGeophysical Research Letters
Volume43
Issue number8
DOIs
StatePublished - Apr 28 2016

Keywords

  • LLSVPs
  • chemical heterogeneities
  • deep mantle
  • magma ocean
  • metallic melt
  • noble gas

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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    Zhang, Z., Dorfman, S. M., Labidi, J., Zhang, S., Li, M., Manga, M., Stixrude, L., McDonough, W. F., & Williams, Q. (2016). Primordial metallic melt in the deep mantle. Geophysical Research Letters, 43(8), 3693-3699. https://doi.org/10.1002/2016GL068560