Saturday, December 15, 2012

Mysterious Metallic Blobs Help Reveal Planets' Innards

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Earth Core Map

By Charles Q. Choi
Yahoo News

      Metallic blobs that rise from Earth's core might help explain the mysterious innards of other planets, new research suggests.

Under the outer crust of the Earth sits the rocky mantle layer and then the planet's metallic, iron-dominated core. Scientists can probe these layers indirectly by measuring how the speed of seismic waves and electrical signals change as they zip through them. Analysis of the lowermost mantle in past studies revealed areas of high electrical conductivity (meaning that electric signals travel very easily) and low seismic velocity, suggesting that iron from the outer core was penetrating the mantle.

However, it remained a mystery as to how iron from the core might extensively chemically interact with the mantle. Known processes for how metal from the core might infiltrate rock in the mantle were either too slow or too small in scale to explain the results that researchers saw.

Now a phenomenon discovered by accident and described in the new study in the Dec. 13 issue of the journal Naturereveals that blobs of iron-rich liquid from the outermost core might have, over the history of the Earth, led to a metal-rich layer up to 60 miles (100 kilometers) thick in the Earth's lower mantle. . . .

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