Sound Velocity of (Mg _0.91 Fe _0.09 ) ₂ SiO ₄ Wadsleyite and Its Implications to Water Distribution in Mantle Transition Zone

Water distribution across the mantle transition zone and its implications for global material circulation

Article history: Accepted 23 November 2010 Available online 13 December 2010 Editor: R.W. Carlson

S velocity reversal in the mantle transition zone

Effect of water on olivine-wadsleyite phase boundary in the (Mg, Fe)2SiO4 system

[1] The phase boundary between San Carlos olivine and its high pressure phase, wadsleyite, have been studied comparatively in dry and water saturated condition. By comparing saturated and dry samples from the same experimental run, we determine that both boundaries of the two-phase coexisting loop shift towards lower pressure or lower iron content, and the pressure width of the loop decreases t...

Messengers from the deep: Fossil wadsleyite-chromite microstructures from the Mantle Transition Zone

Investigations of the Mantle Transition Zone (MTZ; 410-660 km deep) by deformation experiments and geophysical methods suggest that the MTZ has distinct rheological properties, but their exact cause is still unclear due to the lack of natural samples. Here we present the first direct evidence for crystal-plastic deformation by dislocation creep in the MTZ using a chromitite from the Luobusa per...

Elasticity of hydrous wadsleyite to 12 GPa: Implications for Earth’s transition zone

[1] Knowledge of the pressure effect on elasticity of hydrous olivine polymorphs is necessary to model seismic wave speeds for potential hydrous regions of the mantle. Here we report single-crystal elastic properties of wadsleyite, b-Mg2SiO4, with 0.84 wt.% H2O measured to 12 GPa by Brillouin scattering. Pressure derivatives of the aggregate bulk modulus, KS0, and shear modulus, G 0 0, of hydro...