Confirming a pyrolitic lower mantle using self‐consistent pressure scales and new constraints on CaSiO 3 perovskite
نویسندگان
چکیده
منابع مشابه
Oganov Ab initio study of the high - pressure behavior of CaSiO 3 perovskite
Using density functional simulations, within the generalized gradient approximation and projectoraugmented wave method, we study structures and energetics of CaSiO3 perovskite in the pressure range of the Earth’s lower mantle (0–150 GPa). At zero Kelvin temperature the cubic ðPm 3mÞ CaSiO3 perovskite structure is unstable in the whole pressure range, at low pressures the orthorhombic (Pnam) str...
متن کاملCaSiO3 perovskite at lower mantle pressures
[1] We investigate by first-principles the structural behavior of CaSiO3 perovskite up to lower mantle pressures. We confirm that the cubic perovskite modification is unstable at all pressures. The zero Kelvin structure is stabilized by SiO6 octahedral rotations that lower the symmetry to tetragonal, orthorhombic, rhombohedral, or to a cubic supercell. The resulting structures have comparable e...
متن کاملThermoelastic properties of MgSiO(3)-perovskite: insights on the nature of the Earth's lower mantle.
We have determined by means of first principles quasiharmonic calculations the elastic constants and acoustic velocities of MgSiO3 perovskite, the most abundant mineral of the Earth's lower mantle (LM), at pertinent pressures and temperatures. Using these results, along with the effects of low concentration iron alloying and the thermoelasticity of the most important secondary LM phase, MgO, we...
متن کاملCharacteristics of lateral heterogeneities with thermal and chemical origins in the pyrolitic lower mantle
The relative changes between shear and compressional velocities (RSP = o ln VS/o ln VP), bulk sound and shear velocities (RCS = o ln VC/o ln VS), and density versus shear wave velocity (RqS = o ln q/o ln VS) in response to thermal and chemical variations were investigated for the pyrolitic lower mantle. For heterogeneities with thermal origins, RSP increases from 1.7 to 2.0 together with RqS de...
متن کاملPhase transition in MgSiO3 perovskite in the earth’s lower mantle
A new polymorph of MgSiO3 more stable than the Pbnm-perovskite phase has been identified by first-principles computations. It has the CaIrO3 structure with Cmcm symmetry and consists of SiO3 layers intercalated by eightfoldcoordinated Mg ions. High-temperature calculations within the quasiharmonic approximation give a volume change of f 1.5% and a Clapeyron slope of f 7.5F 0.3 MPa/K at f 2750 K...
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ژورنال
عنوان ژورنال: Journal of Geophysical Research: Solid Earth
سال: 2016
ISSN: 2169-9313,2169-9356
DOI: 10.1002/2016jb013062