Interconnection of ferro-periclase controls subducted slab morphology at the top of the lower mantle

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10 Citations (Scopus)

Abstract

The electrical conductivity of mantle rocks during phase transformation from ringwoodite to silicate perovskite and ferro-periclase was measured at 25 GPa and various temperatures ranging from 1300 to 1900 K. The electrical conductivity was high at the initial stage of annealing, suggesting that ferro-periclase forms interconnected layers in aggregates of silicate perovskite and ferro-periclase that are representative of lower mantle rock. At 1900 K the electrical conductivity quickly decreased and reached that of silicate perovskite, suggesting the cut-off of the interconnected ferro-periclase because of rounding of crystals. Below 1700 K, the high conductivity values were maintained for experimental duration. The interconnection of ferro-periclase, which has a lower viscosity than silicate perovskite, can be maintained in a cold descending slab over geological time scales (~1 My), indicating that a colder slab is less viscous than the warmer mantle surrounding it. The low-viscosity slab can be prevented from penetrating into the deeper part of the lower mantle by the high viscosities encountered at a depth of ~1000 km, referred to as the "viscosity hill", that cause stagnation at this depth as observed by seismic tomography.

Original languageEnglish
Pages (from-to)352-357
Number of pages6
JournalEarth and Planetary Science Letters
Volume403
DOIs
Publication statusPublished - Oct 1 2014

Keywords

  • Connectivity
  • Ferro-periclase
  • Subducting slab
  • Viscosity

ASJC Scopus subject areas

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

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