AGU: Geophysical Research Letters

 

Editors' Highlight

Mineral physics theory and the phase transitions in the lower mantle

Observed directly above the core-mantle boundary, large increases in seismic velocities, called the D″ layer, have come into recent scrutiny since scientists discovered a possible new high-temperature, high-pressure crystal packing structure transformed from the common mantle mineral perovskite. Noting that recent research has also hypothesized on the existence of possible seismic discontinuities above and below the D″ layer, Hernlund and Labrosse (2007) sought to see whether such discontinuities were theoretically predicted by mineral physics. Using independent constraints for a lower bound on temperature in the Earth's deep mantle and the temperature of the Earth's inner core boundary, the authors showed that the nature of the transition between perovskite phases, as hypothesized by the existence of the D″ layer and the observed seismic velocity anomalies that bound it, is only consistent with part of the range of uncertainties in current knowledge regarding the pressure-temperature behavior of minerals at such depths.

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