Crystallographers explain seismic anisotropy of Earth’s D’’layer

ETH 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 tectonics 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”.

For more information and pictures:
Prof. Artem R. Oganov
ETH Zurich, Laboratory of Crystallography
Phone +4 +41(0)44 632 37 52 or +41(0)43 300 18 73
E-Mail a.oganov@mat.ethz.ch

All latest news from the category: Earth Sciences

Earth Sciences (also referred to as Geosciences), which deals with basic issues surrounding our planet, plays a vital role in the area of energy and raw materials supply.

Earth Sciences comprises subjects such as geology, geography, geological informatics, paleontology, mineralogy, petrography, crystallography, geophysics, geodesy, glaciology, cartography, photogrammetry, meteorology and seismology, early-warning systems, earthquake research and polar research.

Back to home

Comments (0)

Write a comment

Newest articles

Lighting up the future

New multidisciplinary research from the University of St Andrews could lead to more efficient televisions, computer screens and lighting. Researchers at the Organic Semiconductor Centre in the School of Physics and…

Researchers crack sugarcane’s complex genetic code

Sweet success: Scientists created a highly accurate reference genome for one of the most important modern crops and found a rare example of how genes confer disease resistance in plants….

Evolution of the most powerful ocean current on Earth

The Antarctic Circumpolar Current plays an important part in global overturning circulation, the exchange of heat and CO2 between the ocean and atmosphere, and the stability of Antarctica’s ice sheets….

Partners & Sponsors