Viscosity jump in the lower mantle inferred from melting curves of ferropericlase

Jie Deng, Kanani K.M. Lee

Research output: Contribution to journalArticlepeer-review

44 Scopus citations

Abstract

Convection provides the mechanism behind plate tectonics, which allows oceanic lithosphere to be subducted into the mantle as "slabs" and new rock to be generated by volcanism. Stagnation of subducting slabs and deflection of rising plumes in Earth's shallow lower mantle have been suggested to result from a viscosity increase at those depths. However, the mechanism for this increase remains elusive. Here, we examine the melting behavior in the MgO-FeO binary system at high pressures using the laser-heated diamond-anvil cell and show that the liquidus and solidus of (Mg x Fe1-x )O ferropericlase (x = ~0.52-0.98), exhibit a local maximum at ~40 GPa, likely caused by the spin transition of iron. We calculate the relative viscosity profiles of ferropericlase using homologous temperature scaling and find that viscosity increases 10-100 times from ~750 km to ~1000-1250 km, with a smaller decrease at deeper depths, pointing to a single mechanism for slab stagnation and plume deflection.

Original languageEnglish (US)
Article number1997
JournalNature communications
Volume8
Issue number1
DOIs
StatePublished - Dec 1 2017
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • General Biochemistry, Genetics and Molecular Biology
  • General Physics and Astronomy

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