RheoMan: a five-year, ERC-funded (Advanced Grant), project to model the rheology of the Earth's mantle

Sep 17, 2016 Stalled Slabs? Blame Wadsleyite Results

The last paper of Sebastian Ritterbex on lattice friction modelling in wadsleyite has been selected as a notable paper by the editors of American Mineralogist

Editors Selections of American Mineralogist, September 2016


Stalled Slabs? Blame Wadsleyite

On page 2085 of the september issue of Am. Min., Ritterbex et al. develop a model for dislocation creep in wadsleyite that can be applied to the strain rates and pressure-temperature conditions relevant to Earth’s transition zone (410-660 km). The mineral wadsleyite, a polymorph of (Mg,Fe)2SiO4, is a dominant phase in Earth’s transition zone (410-520 km) with olivine stable at shallower depths, and ringwoodite at greater depths (520-660 km). In an earlier study, Ritterbex and others showed that even the “easiest” of dislocation slip mechanisms in ringwoodite were too inefficient to drive deformation at the base of the upper mantle. The authors extend this work to wadsleyite, obtaining a similar result. These results explain why some subducted slabs stall within or at the base of the transition zone: resistance to subduction may reflect a substantial increase in resistance to deformation as (Mg,Fe)2SiO4 transforms from olivine to wadsleyite, and eventually ringwoodite.

 

S. Ritterbex, Ph. Carrez & P. Cordier (2016) Modeling dislocation glide and lattice friction in Mg2SiO4 wadsleyite in conditions of the Earth’s transition zone. Americal Mineralogist, doi: 10.2138/am-2016-5578CCBYNCND Open access