Intracrystalline Olivine-Ringwoodite Transformation and Time-Dependent Growth Rates
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During the transformation of olivine (Fo<SUB>90</SUB>) to ringwoodite and wadsleyite at 18-20 GPa three transformation microstructures develop: (i) Reaction rims form around olivine by incoherent grain boundary nucleation; the growth rates of these rims decrease strongly with reaction time because the volume decrease causes elastic strain to develop. (ii) Intracrystalline, coherent ringwoodite lamellae nucleate on previously formed (100) <SUB>α</SUB> stacking faults. (iii) Polycrystalline ringwoodite and/or wadsleyite lenses develop in the interior of relict olivine crystals by nucleation of incoherent grains on the coherent ringwoodite lamellae. The observed intracrystalline transformation mechanism and the time-dependence of growth have important implications for predicting the depth of the olivine-spinel transformation in subducting lithosphere.
- The Review of High Pressure Science and Technology
The Review of High Pressure Science and Technology 7, 28-33, 1998
The Japan Society of High Pressure Science and Technology