Allen McNamara. (Credit: Image courtesy of Arizona State University, Photo by Tom Story)
Allen McNamara. (Credit: Image courtesy of Arizona State University, Photo by Tom Story)
Scientific maverick’s theory on Earth’s core up for a test
SF Chronicle | Monday, November 29, 2004 | Keay Davidson
Posted on 12/05/2004 2:17:28 PM EST by SunkenCiv
http://www.freerepublic.com/focus/f-chat/1294934/posts
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Mineral Physics Illuminates Lower Mantle HypothesisScientists 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.
Science Daily
March 24, 2007
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.
ping for later
