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 language | English |
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Pages (from-to) | 352-357 |
Number of pages | 6 |
Journal | Earth and Planetary Science Letters |
Volume | 403 |
DOIs | |
Publication status | Published - 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