Melting-induced stratification above the Earth’s inner core due to convective translation

  title={Melting-induced stratification above the Earth’s inner core due to convective translation},
  author={Thierry Alboussi{\`e}re and R. Deguen and Mickael Melzani},
In addition to its global North–South anisotropy, there are two other enigmatic seismological observations related to the Earth’s inner core: asymmetry between its eastern and western hemispheres and the presence of a layer of reduced seismic velocity at the base of the outer core. This 250-km-thick layer has been interpreted as a stably stratified region of reduced composition in light elements. Here we show that this layer can be generated by simultaneous crystallization and melting at the… 

Melting of the Earth’s inner core

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Thermal convection in Earth's inner core with phase change at its boundary

Inner core translation, with solidification on one hemisphere and melting on the other, provides a promising basis for understanding the hemispherical dichotomy of the inner core, as well as the

Earth’s solid inner core: Seismic implications of freezing and melting

Seismic P velocity structure is determined for the upper 500 km of the inner core and lowermost 200 km of the outer core from differential travel times and amplitude ratios. Results confirm the

Sharp hemisphere boundaries in a translating inner core

Geodynamic models of a convectively translating inner core have recently been proposed that would account for the seismically observed differences in isotropic velocity between the eastern and

Heterogeneity and Anisotropy of Earth's Inner Core

Seismic observations provide strong evidence that Earth's inner core is anisotropic, with larger velocity in the polar than in the equatorial direction. The top 60–80 km of the inner core is

Distinct layering in the hemispherical seismic velocity structure of Earth's upper inner core

The existence of hemispherical variation in the Earth's inner core is well-documented, but consensus has not yet been reached on its detailed structure. The uppermost layers are a region of

Convection in the Earth's inner core

The feasibility of thermal and compositional convection in Earth’s inner core

Inner core convection, and the corresponding variations in grain size and alignment, has been proposed to explain the complex seismic structure of the inner core, including its anisotropy, lateral



A thermochemical boundary layer at the base of Earth's outer core and independent estimate of core heat flux

SUMMARY Recent seismological observations suggest the existence of a ≈150-km-thick density-stratified layer with a P-wave velocity gradient that differs slightly from PREM. Such a structure can only

Onset and orientation of convection in the inner core

SUMMARY Thermal convection is an effective mechanism for producing seismic anisotropy in many regions of the Earth. However, it is not known whether this mechanism is relevant for the anisotropy

A convection model to explain anisotropy of the inner core

Seismic evidence suggests that the solid inner core of the Earth may be anisotropic. Several models have been proposed to explain this anisotropy as the result of preferred orientation of crystals.

Convection within the inner‐core and thermal implications

Estimation of the Rayleigh numbers of the inner-core leads to the conclusion that, even with low internal heating rates, this region of the Earth is convecting. This work presents an axisymmetrical

Hemispherical variations in seismic velocity at the top of the Earth's inner core

These residuals show no correlation with the angle at which the waves traverse the inner core, indicating that seismic anisotropy is not strong in this region and that the isotropic seismic velocity of the eastern hemisphere is about 0.8% higher than that of the western hemisphere.

Large-scale variations in inner core anisotropy

I analyze nearly 2000 handpicked differential times of core-penetrating compressional waves to image lateral variations in the anisotropic structure of the solid inner core. The inner core is

Dislocation melting of iron and the temperature of the inner core boundary, revisited

Summary The melting point Tm of iron at conditions of the Earth's inner core boundary (ICB) has been calculated from the dislocation theory of melting in metals. These calculations take into

Gross thermodynamics of two-component core convection

We model the inner core by an alloy of iron and 8 per cent sulphur or silicon and the outer core by the same mix with an additional 8 per cent oxygen. This composition matches the densities of

Physical properties of the Earth's core

The core plays a major part in the Earth's dynamics. It is essentially molten iron with about 10 to 15 wt% light elements in solution, probably mostly silicon and sulfur' with some oxygen that can be