Back-transformation processes in high-pressure minerals: implications for planetary collisions and diamond transportation from the deep Earth

Abstract We conducted back-transformation experiments in ringwoodite, bridgmanite, and lingunite at 0.47–8.1 GPa 310–920 °C by situ X-ray observation method. Ringwoodite back-transformed to olivine grain-boundary nucleation growth mechanism. The site saturation occurred the early stage under conditions far from equilibrium boundary, we observed growth-controlled kinetics ringwoodite. determined present study is largely different that previous (Reynard et al. Am Min 81:585–594, 1996), which may be due effects of water. Bridgmanite did not directly back-transform stable phase orthoenstatite ~ 1–4 GPa, but first becomes amorphous with increasing temperatures. crystallization bridgmanite was controlled both processes. temperature range state became narrow pressures, direct high-P clinoenstatite without amorphization eventually 8 GPa. Amorphization also when 1.5 GPa; however, plagioclase proceeded before complete amorphization. ringwoodite variedly occurs shocked meteorites depending on degree post-shock annealing, can reasonably interpreted based kinetics. On other hand, presence hydrous diamond inclusions cannot explained help residual stress. indicates or enstatite unavoidable during annealing. This inconsistent crystalline meteorites, still requiring further investigations kinetic behaviors shorter timescales.