ETH researchers discovered a very unusual mechanism of plastic deformation in the Earths 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 Earths 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 Earths 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 Earths mantle
Anke Poiger | idw
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