Plastic deformation of wadsleyite: II. High-pressure deformation in shear

We have studied the dislocation microstructures that develop in (Mg0.9Fe0.1)(2)SiO4 wadsleyite deformed by simple shear at high pressure. The experiments were performed in a multianvil apparatus with the shear assembly designed by Karato and Rubie (1997). The samples were synthesized in a separate experiment from high-purity oxides. The deformation experiments were carried out at 14 GPa and 1300 degreesC with time durations ranging from 1 to 8 h leading to plastic shear strains of 60 and 73%, respectively. The microstructures investigated by transmission electron microscopy (TEM) show that dislocation glide is activated under these conditions over the whole experimental time. The easy slip systems at 1300 degreesC involve 1/2<111> dislocations gliding in {101} as well as [100] dislocations gliding in (010) and {011}.