Transmission electron microscope observation of α, β and γ (Mg, Fe)2SiO4 in shocked meteorites: planar defects and polymorphic transitions

Transformation textures, mechanisms of formation of high‐pressure minerals in shock melt veins of L6 chondrites, and pressure‐temperature conditions of the shock events

“…Wadsleyite has been identified in many shocked ordinary chondrites, Martian meteorites, and lunar meteorites (e.g., Putnis and Price 1979;Madon and Poirier 1983;Price 1983;Price et al 1983;Kimura et al 2000;Malavergne et al 2001;Barrat et al 2005). Most previously reported wadsleyite has been associated with ringwoodite.…”

Simulation of screw dislocations in wadsleyite

“…Studies of samples from meteorites (e.g. Price et al, 1982; Dislocations in wadsleyite 5 Price, 1983;Madon and Poirier, 1983) and experiments (e.g. Kerschhofer et al, 1996Kerschhofer et al, , 1998 show that transformation between olivine and wadsleyite can occur via incoherent nucleation on olivine grain boundaries or by an intracrystalline mechanism involving the migration of partial dislocations.…”

Ringwoodite lamellae in olivine: Clues to olivine–ringwoodite phase transition mechanisms in shocked meteorites and subducting slabs

“…This study suggests that the time duration of high pressure and temperature for the growth of ringwoodite lamellae might have lasted at least for several seconds, and that an intracrystalline transformation mechanism of ringwoodite in olivine could favorably operate in the subducting lithospheric slabs in the deep Earth. N atural ringwoodite had been found in many shocked chondritic meteorites, in which the ringwoodite occurs as finegrained polycrystalline aggregates formed through a phase transition of olivine during exogenous dynamic events on the parent asteroids (1)(2)(3)(4). It was also suggested that the olivineringwoodite transformation could take place in cold subducting slabs at the deep transition zone, where pressure oversteps the ringwoodite stability field (5)(6)(7)(8)(9)).…”