To answer the big questions, it often helps to look at the smallest details. That is the approach Stanford mineral physicist Wendy Mao is taking to understanding a major event in Earth's inner history. Using a new technique to scrutinize how minute amounts of iron and silicate minerals interact at ultra-high pressures and temperatures, she is gaining insight into the biggest transformation Earth has ever undergone the separation of its rocky mantle from its iron-rich core approximately 4.5 billion years ago.
The technique, called high-pressure nanoscale X-ray computed tomography, is being developed at SLAC National Accelerator Laboratory. With it, Mao is getting unprecedented detail in three-dimensional images of changes in the texture and shape of molten iron and solid silicate minerals as they respond to the same intense pressures and temperatures found deep in the Earth.
Mao will present the results of the first few experiments with the technique at the annual meeting of the American Geophysical Union in San Francisco on Thursday, Dec. 16.
Tomography refers to the process that creates a three-dimensional image by combining a series of two-dimensional images, or cross-sections, through an object. A computer program interpolates between the images to flesh out a recreation of the object.
Researchers at SLAC have developed a way to combine a diamond anvil cell, which compresses tiny samples between the tips of two diamonds, with nanoscale X-ray computed tomography to capture images of material at high pressure. The pressures deep in the Earth are so high millions of times atmospheric pressure that only diamonds can exert the needed pressure without breaking under the force.
At present, the SLAC researchers and their collaborators from HPSync, the High Pressure Synergetic Consortium at the Advanced Photon Source at Argonne National Laboratory, are the only group using this technique.
"It is pretty exciti
|Contact: Louis Bergeron|