High-Pressure Deformation Techniques in Experimental Geophysics

2013 ◽  
Vol 772 ◽  
pp. 45-49
Author(s):  
Hans J. Mueller
Keyword(s):  
High Pressure ◽  
Lower Mantle ◽  
Mineral Content ◽  
Rock Deformation ◽  
Frequency Range ◽  
Earth’S Mantle ◽  
The Past ◽  
Experimental Rock ◽  
Deformation Processes ◽  
Experimental Rock Deformation

Deformation processes have extrordinary importance for Geosciences. Mountainbuilding, i.e. orogenesis, slab subduction, continent-continent collision and penetration of the Earth’s mantle transition zone are examples of such processes. There is also a strong correlation between mineral content, phase transitions and structural properties of natural rocks. Ductile rock deformation is a typical property for Earth’s mantle conditions. Nevertheless most of experimental rock deformation was conducted under crustal conditions in the past. So, it was a revolutionary event when the first Deformation-DIA was introduced about a decade ago. Today this technique is indispensable not only for rock deformation under unextrapolated Earth’s mantle conditions but also for attenuation measurements in the seismic frequency range and attaining of lower mantle conditions in Large Volume Presses. In principle all these techniques require the installation of the high pressure device at a 3rd generation light source.

scholarly journals High-pressure phase of brucite stable at Earth’s mantle transition zone and lower mantle conditions

2016 ◽  
Vol 113 (49) ◽  
pp. 13971-13976 ◽  
Author(s):  
Andreas Hermann ◽  
Mainak Mookherjee
Keyword(s):  
High Pressure ◽  
Transition Zone ◽  
Lower Mantle ◽  
Direct Detection ◽  
Geophysical Methods ◽  
High Pressure Phase ◽  
Mantle Transition Zone ◽  
Earth’S Mantle ◽  
3D Network ◽  
Pressure Phase

We investigate the high-pressure phase diagram of the hydrous mineral brucite, Mg(OH)2, using structure search algorithms and ab initio simulations. We predict a high-pressure phase stable at pressure and temperature conditions found in cold subducting slabs in Earth’s mantle transition zone and lower mantle. This prediction implies that brucite can play a much more important role in water transport and storage in Earth’s interior than hitherto thought. The predicted high-pressure phase, stable in calculations between 20 and 35 GPa and up to 800 K, features MgO6 octahedral units arranged in the anatase–TiO2 structure. Our findings suggest that brucite will transform from a layered to a compact 3D network structure before eventual decomposition into periclase and ice. We show that the high-pressure phase has unique spectroscopic fingerprints that should allow for straightforward detection in experiments. The phase also has distinct elastic properties that might make its direct detection in the deep Earth possible with geophysical methods.

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