scholarly journals Constraints on the composition and temperature of LLSVPs from seismic properties of lower mantle minerals

2021 ◽  
Vol 554 ◽  
pp. 116685
Author(s):  
Kenny Vilella ◽  
Thomas Bodin ◽  
Charles-Edouard Boukaré ◽  
Frédéric Deschamps ◽  
James Badro ◽  
...  
Keyword(s):  
Lower Mantle ◽  
Mantle Minerals ◽  
Seismic Properties

scholarly journals Xenon iron oxides predicted as potential Xe hosts in Earth’s lower mantle

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Feng Peng ◽  
Xianqi Song ◽  
Chang Liu ◽  
Quan Li ◽  
Maosheng Miao ◽  
...  
Keyword(s):  
Iron Oxides ◽  
Lower Mantle ◽  
Search Algorithm ◽  
Mass Density ◽  
Mantle Minerals ◽  
Fe Oxides ◽  
Structure Search ◽  
Wide Range ◽  
Deep Earth ◽  
Calculated Mass

Abstract An enduring geological mystery concerns the missing xenon problem, referring to the abnormally low concentration of xenon compared to other noble gases in Earth’s atmosphere. Identifying mantle minerals that can capture and stabilize xenon has been a great challenge in materials physics and xenon chemistry. Here, using an advanced crystal structure search algorithm in conjunction with first-principles calculations we find reactions of xenon with recently discovered iron peroxide FeO2, forming robust xenon-iron oxides Xe2FeO2 and XeFe3O6 with significant Xe-O bonding in a wide range of pressure-temperature conditions corresponding to vast regions in Earth’s lower mantle. Calculated mass density and sound velocities validate Xe-Fe oxides as viable lower-mantle constituents. Meanwhile, Fe oxides do not react with Kr, Ar and Ne. It means that if Xe exists in the lower mantle at the same pressures as FeO2, xenon-iron oxides are predicted as potential Xe hosts in Earth’s lower mantle and could provide the repository for the atmosphere’s missing Xe. These findings establish robust materials basis, formation mechanism, and geological viability of these Xe-Fe oxides, which advance fundamental knowledge for understanding xenon chemistry and physics mechanisms for the possible deep-Earth Xe reservoir.

THEORETICAL PREDICTION OF DEBYE TEMPERATURE FOR MANTLE MINERALS AT HIGH TEMPERATURES

2011 ◽  
Vol 25 (12) ◽  
pp. 1593-1600 ◽  
Author(s):  
ANJANI K. PANDEY ◽  
ABHAY P. SRIVASTAVA
Keyword(s):  
Shear Modulus ◽  
Elastic Properties ◽  
Laboratory Data ◽  
Seismic Velocities ◽  
Mantle Minerals ◽  
Seismic Properties ◽  
Debye Temperatures ◽  
Temperature Ranges ◽  
Experimental Values ◽  
Good Agreement

The seismic properties of a material depend on composition, crystal structure, temperature, pressure and in some cases defect concentrations. Most of the earth is made up of crystals. The elastic properties of crystals depend on orientation and frequency. Thus, the interpretation of seismic data or the extrapolation of laboratory data requires knowledge of crystal or mineral physics, elasticity and thermodynamics. In the present work, we calculated the shear modulus, seismic velocities and Debye temperatures at different high temperature ranges. The temperature dependence of elastic properties such as shear modulus, seismic velocities and Debye temperatures has been measured using Hill's averaging method and other thermodynamic methods for five silicate mantle minerals viz. MgAl 2 O 4, Mg 2 SiO 4, Fe 2 SiO 4, Mn 2 SiO 4, and Co 2 SiO 4. The results are found to be in good agreement with experimental values.

The Lower Mantle Minerals in Ophiolite-hosted Diamond

2015 ◽  
Vol 89 (s2) ◽  
pp. 108-109 ◽  
Author(s):  
Jingsui YANG ◽  
Richard WIRTH ◽  
Fahui XIONG ◽  
Yazhou TIAN ◽  
Zhu HUANG ◽  
...  
Keyword(s):  
Lower Mantle ◽  
Mantle Minerals

Ab Initio Study on the Lower Mantle Minerals

2020 ◽  
Vol 48 (1) ◽  
pp. 99-119 ◽  
Author(s):  
Taku Tsuchiya ◽  
Jun Tsuchiya ◽  
Haruhiko Dekura ◽  
Sebastian Ritterbex
Keyword(s):  
Thermal Conductivity ◽  
High Pressure ◽  
High Temperature ◽  
Ab Initio ◽  
Lower Mantle ◽  
Recent Progress ◽  
A Priori ◽  
Computation Method ◽  
S Wave ◽  
Mantle Minerals

Recent progress in theoretical mineral physics based on the ab initio quantum mechanical computation method has been dramatic in conjunction with the rapid advancement of computer technologies. It is now possible to predict stability, elasticity, and transport properties of complex minerals quantitatively with uncertainties that are comparable to or even smaller than those attached in experimental data. These calculations under in situ high-pressure ( P) and high-temperature conditions are of particular interest because they allow us to construct a priori mineralogical models of the deep Earth. In this article, we briefly review recent progress in studying high- P phase relations, elasticity, thermal conductivity, and rheological properties of lower mantle minerals including silicates, oxides, and some hydrous phases. Our analyses indicate that the pyrolitic composition can describe Earth's properties quite well in terms of density and P- and S-wave velocity. Computations also suggest some new hydrous compounds that could persist up to the deepest mantle and that the postperovskite phase boundary is the boundary of not only the mineralogy but also the thermal conductivity. ▪  The ab initio method is a strong tool to investigate physical properties of minerals under high pressure and high temperature. ▪  Calculated thermoelasticity indicates that the pyrolytic composition is representative to the chemistry of Earth's lower mantle. ▪  Simulations predict new dense hydrous phases stable in the whole lower mantle pressure and temperature condition. ▪  Calculated lattice thermal conductivity suggests a heat flow across the core mantle boundary no greater than 10 TW.

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