Researchers unlock mystery of layer encircling the Earth's core

Jan 30, 2006
Earth from space

University of Minnesota associate professor of chemical engineering Renata Wentzcovitch and her team of researchers have confirmed the properties of a mineral (post-perovskite) that may form near the Earth's core in a layer called the D'' region.

The work offers new insight for interpreting properties of this region. The D'' (Dee double prime) layer surrounds Earth's core and is between 0 and 186 miles thick. It is at the interface between two chemically distinct regions, the rocky mantle and the metallic core. The article, "MgSiO3 post-perovskite at D'' conditions," was published on Jan. 17 in Proceedings of the National Academy of Science.

The research "tells us how to better model Earth's internal processes," said Wentzcovitch. "Proper geodynamical modeling of the Earth is necessary to get a better grasp of the dynamics of the surface. You can't fully understand Earth's surface motion without understanding how it moves inside. What's unbelievable is how well we can model Earth on a big scale. At this scale, small details don't matter."

In 2004, Japanese researchers at the Tokyo Institute of Technology found that high temperatures and pressures transform perovskite, the major mineral in Earth's mantle, into a new mineral called post-perovskite. Wentzcovitch's group contributed to this discovery by determining the structure of post-perovskite and by calculating the pressure and temperature conditions for its existence. They matched the conditions in the D'' layer.

In the current work, Wentzcovitch and colleagues demonstrate that the seismic properties of post-perovskite are much like the previously inexplicable properties found in the D'' layer. This is the most convincing evidence that post-perovskite is in the D'' layer and produces its strange seismic properties.

"As the Earth cools, D'' becomes thicker. Its thickness is related to Earth's age and its aging processes. The discovery of post-perovskite in the D'' layer will also help us understand how the Earth has evolved," Wenttzcovitch said.

On the web: www.pnas.org/content/vol103/issue3/#GEOPHYSICS

Source: University of Minnesota

Explore further: Suddenly, the sun is eerily quiet: Where did the sunspots go?

add to favorites email to friend print save as pdf

Related Stories

New planthopper species found in southern Spain

1 hour ago

Not much is known about the the genus of planthopper known as Conosimus, which now includes six species after a new one was recently discovered in the southern part of the Iberian Peninsula in the Spanish ...

Ex-Qualcomm exec pleads guilty to insider trading

8 hours ago

A former high-ranking executive of US computer chip giant Qualcomm pleaded guilty Monday to insider trading charges, including trades on a 2011 deal for Atheros Communications, officials said.

Media venture creates press litigation fund

9 hours ago

The media venture created by entrepreneur Pierre Omidyar said Monday it was establishing a fund to help defend journalists in cases involving freedom of the press.

Recommended for you

The heart of an astronaut, five years on

1 hour ago

The heart of an astronaut is a much-studied thing. Scientists have analyzed its blood flow, rhythms, atrophy and, through journal studies, even matters of the heart. But for the first time, researchers are ...

User comments : 0