ETH crystallographers explain seismic anisotropy of Earth's D-layer

May 11, 2006
Earth from space
Earth from space

ETH Zürich researchers discovered a very unusual mechanism of plastic deformation in the Earth's mantle. Furthermore, they have predicted a new family of mantle minerals. These discoveries shed new light on the plastic flow of mantle rocks inside our planet - the process that controls plate tectonics and the associated earthquakes, volcanism, and continental drift.

Plastic flow in the Earth's mantle is the microscopic process behind plate tecton-ics and the associated continental drift, volcanism and earthquakes. Seismic anisotropy is the main signature of plastic flow inside the Earth. Its character depends on the properties of Earth-forming minerals.

Simulations have provided a new insight that leads to a more consistent picture of the dynamics of our planet. According to seismic observations, the lowermost 150 km of the Earth's mantle, known as the D" layer, possess many unusual properties. Many of these anomalies were explained by the properties of post-perovskite (Mg,Fe)SiO3, the dominant mineral of the D" layer. Still, it remained difficult to explain the observed strong seismic anisotropy of the D" layer. Now, thanks to metadynamics, a novel simulation methodology, ETH researcher Artem R. Oganov and colleagues have explained these seismic observations.

They came up with an unexpected mechanism of plastic deformation of post-perovskite involving the formation of nanoscale slices of the lower-pressure perovskite structure along the (110) planes of post-perovskite. The ETH researchers could show that this mechanism fully explains the observed seismic anisotropy and some geophysical observations are consistent only with this mechanism.

New minerals in the Earth's mantle

Structures containing slices of the perovskite and post-perovskite structures are not only a result of plastic deformation. Researchers have predicted a whole infinite family of minerals of the same composition, (Mg,Fe)SiO3, built of alternating nanoscale slices of the perovskite and post-perovskite structures.

According to quantummechanical calculations of ETH researcher Artem R. Oganov and colleagues, such unusual minerals could become important stable minerals in the Earth's mantle. Several research groups are now trying to synthesize these predicted minerals. If successful, these attempts will lead to a new mineralogical model of the Earth's interior. The research results have been published in the end of 2005 in Nature.

Source: ETH Zürich

Explore further: New study confirms water vapor as global warming amplifier

add to favorites email to friend print save as pdf

Related Stories

Fukushima study: Think about unthinkable disasters

55 minutes ago

(AP)—A U.S. science advisory report says a key lesson from Japan's Fukushima nuclear accident is that the nation's nuclear industry needs to focus more on the highly unlikely but super-serious worst case scenarios.

FX says overnight ratings becoming meaningless

1 hour ago

(AP)—It's a rite nearly as old as television: the morning after a new show premieres, network executives wait impatiently for the Nielsen company's estimate of how many people watched, and rush to report ...

Recommended for you

Huge waves measured for first time in Arctic Ocean

5 hours ago

As the climate warms and sea ice retreats, the North is changing. An ice-covered expanse now has a season of increasingly open water which is predicted to extend across the whole Arctic Ocean before the middle ...

New research reveals Pele is powerful, even in the sky

10 hours ago

One might assume that a tropical storm moving through volcanic smog (vog) would sweep up the tainted air and march on, unchanged. However, a recent study from atmospheric scientists at the University of Hawai'i ...

Image: Wildfires continue near Yellowknife, Canada

11 hours ago

The wildfires that have been plaguing the Northern Territories in Canada and have sent smoke drifting down to the Great Lakes in the U.S. continue on. NASA's Aqua satellite collected this natural-color image ...

Excavated ship traced to Colonial-era Philadelphia

12 hours ago

Four years ago this month, archeologists monitoring the excavation of the former World Trade Center site uncovered a ghostly surprise: the bones of an ancient sailing ship. Tree-ring scientists at Columbia ...

User comments : 0