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Distinguished Speaker Miyagi Offers a "Mineralogist's Perspective"

EES welcomes Dr. Lowell Miyagi of University of Utah as our Distinguished Speaker this week.

"A Mineralogist's Perspective on Mantle Convection"

Mantle convection is the internal engine that drives dynamic processes of the solid Earth. Plate tectonics, the surface expression of convection has a profound impact on the Earth’s surface through processes such as mountain building, earthquakes, and volcanism. However, there is no direct method for imaging mantle flow and our understanding of mantle convection remains limited.  In the late 60’s it was realized that anisotropic propagation of seismic waves in the upper mantle is due to crystallographic preferred orientation (texture) of minerals that that develops during mantle convection.  If the relationship between deformation geometry, texture development, and seismic anisotropy are well understood, observations of seismic anisotropy can be used to map flow patterns in the Earth’s interior.  For upper mantle rocks naturally deformed samples and an extensive literature of experimental deformation studies are available, and the use of anisotropy to map upper mantle flow has revolutionized our understanding of mantle dynamics.  

The lower mantle, as the largest region of the Earth, plays a key role in the internal dynamics of our planet.  However due to experimental challenges and the lack of naturally deformed samples, deformation mechanisms for rocks and mineral phases that exist in the lower mantle are poorly constrained.  As a result interpretation of seismic anisotropy in terms of flow in the lower mantle remains poorly constrained.  By using novel deformation devices such as the diamond anvil cell and multi anvil press we can perform deformation experiments on lower mantle phases at ultra-high pressures and temperatures.  This talk will discuss deformation mechanisms and texture development in mineral phase relevant to the lower mantle, as well as the implications of these results for understanding large scale flow patterns in the Earth’s interior.

Join us for this perspective on mantle convection on Friday, October 18, 2019 at 12:30 PM in Room 204, Natural Science Building on the East Lansing Campus.

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Dr. Jeffrey Freymueller
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