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BookmarkScienceDaily (Mar. 24, 2007) — Scientists have shown increased interest in a mantle layer known as D", presumed to be just above the core-mantle boundary, since laboratory experiments in 2004 revealed a possible new high-temperature, high-pressure, crystal packing structure derived from the common mantle mineral perovskite.
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Noting that recent research has also hypothesized the existence above and below the D" layer of discontinuities in the velocities of seismic waves, Hernlund and Labrosse investigate whether such discontinuities are theoretically predicted by mineral physics.
Using independent constraints for a lower bound on temperature in the Earth's deep mantle and for the temperature of the Earth's inner core boundary, the authors examine the nature of the transition between perovskite phases, as hypothesized by the existence of the D" layer and the observed seismic velocity anomalies. They find it consistent only with part of the range of uncertainties in current knowledge of the pressure-temperature behavior of minerals at such depths.
Title: Geophysically consistent values of the perovskite to post-perovskite transition Clapeyron slope
Authors: J. W. Hernlund: Institute de Physique du Globe de Paris, Paris, France; S. Labrosse: Laboratoire des Sciences de la Terre, École Normale Supérieure de Lyon, Lyon, France
Source: Geophysical Research Letters (GRL) paper 10.1029/2006GL028961, 2007
