Magnesium silicate perovskite coexisting with ringwoodite in harzburgite stagnated at the lowermost mantle transition zone

The presence of magnesium silicate perovskite coexisting with ringwoodite and a very small amount of calcium silicate perovskite in a harzburgite composition was observed at pressures of 22.5–23.5 GPa and a fixed temperature of 1600 °C. The silicate perovskites are products of pressure-induced phase transformation in non-olivine component in the harzburgite. The postspinel transition occurs at 24 GPa in the olivine component and the harzburgite consists of the silicate perovskites and magnesiowüstite above 24 GPa. The possible presence of magnesium silicate perovskite in harzburgite at lowermost mantle transition zone may contribute to high velocity anomalies in stagnant slabs.