Thermoelastic properties of ringwoodite (Fex,Mg1−x)2SiO4: Its relationship to the 520km seismic discontinuity

We combine density functional theory (DFT) within the local density approximation (LDA), the quasiharmonic approximation (QHA), and a model vibrational density of states (VDoS) to calculate elastic moduli and sound velocities of γ-(Fex,Mg1−x)2SiO4 (ringwoodite), the most abundant mineral of the lowe...

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Bibliographic Details
Published in:Earth and planetary science letters 2012-10, Vol.351-352, p.115-122
Main Authors: Núñez Valdez, Maribel, Wu, Zhongqing, Yu, Yonggang G., Revenaugh, Justin, Wentzcovitch, Renata M.
Format: Article
Language:English
Subjects:
520 km discontinuity
Approximation
Density
Discontinuity
Earth
elasticity
first principles
Mathematical analysis
ringwoodite
Seismic engineering
Seismic phenomena
Thermoelastic properties
transition zone
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Summary:We combine density functional theory (DFT) within the local density approximation (LDA), the quasiharmonic approximation (QHA), and a model vibrational density of states (VDoS) to calculate elastic moduli and sound velocities of γ-(Fex,Mg1−x)2SiO4 (ringwoodite), the most abundant mineral of the lower Earth's transition zone (TZ). Comparison with experimental values at room-temperature and high pressure or ambient-pressure and high temperature shows good agreement with our first-principles findings. Then, we investigate the contrasts associated with the β→γ(Fex,Mg1−x)2SiO4 transformation at pressures and temperatures relevant to the TZ. This information offers clearly defined reference values to advance the understanding of the nature of the 520km seismic discontinuity.
ISSN:0012-821X
1385-013X
DOI:10.1016/j.epsl.2012.07.024