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News & Views |
Oxygen-rich melt in deep magma oceans
High pressures may have enabled ferric iron-rich silicate melts to coexist with iron metal near the base of magma oceans early in the history of large rocky planets like Earth. This suggests a relatively oxygen-rich atmosphere during the late stages of core formation on these planets.
- Fabrice Gaillard
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Article |
Hadean mantle oxidation inferred from melting of peridotite under lower-mantle conditions
The early Earth’s mantle rapidly oxidized during the Hadean because of iron disproportionation and core segregation, according to experiments melting peridotite under deep-mantle conditions.
- Hideharu Kuwahara
- , Ryoichi Nakada
- & Tetsuo Irifune
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Article |
Primordial helium extracted from the Earth’s core through magnesium oxide exsolution
Primordial helium in the deep mantle may be supplied continuously from Earth’s core, according to first-principles calculations and modelling of helium partitioning into exsolved magnesium oxide at core–mantle boundary conditions
- Jie Deng
- & Zhixue Du
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Article |
Longitudinal structure of Earth’s magnetic field controlled by lower mantle heat flow
The pattern of heat flow across the core–mantle boundary results in longitudinal differences in geomagnetic field behaviour, according to geodynamo modelling.
- Jonathan E. Mound
- & Christopher J. Davies
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Research Briefing |
Differential rotation of the Earth’s inner core changes over decades and has come to near-halt
Seismic observations reveal that the Earth’s inner core oscillates with a period of approximately seven decades. The multidecadal periodicity coincides with that of several other geophysical observations, particularly the variations in the length of day and the Earth’s magnetic field, suggesting dynamic interactions between the major layers of the Earth.
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Article |
Multidecadal variation of the Earth’s inner-core rotation
Multidecadal oscillation of the Earth’s inner core, coinciding with length of day and magnetic field variations, is experiencing a pause and reversing, according to analysis of repeating seismic waves traversing the inner core since the 1960s.
- Yi Yang
- & Xiaodong Song
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Article |
An initial map of fine-scale heterogeneity in the Earth’s inner core
Two regions of fine-scale heterogeneity in Earth’s inner core may be due to the random alignment of fast-freezing crystals associated with downwelling in the mantle and outer core, according to a 3D map of inner-core seismic data.
- Wei Wang
- & John E. Vidale
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News & Views |
Sulfur evaporation in planetesimals
Evaporative loss of sulfur from molten planetesimals can explain the sub-chondritic sulfur isotope composition of the bulk silicate mantle, suggesting an important role for planetesimal evaporation in establishing Earth’s volatile budget.
- Yuan Li
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Article |
Sulfur isotopic signature of Earth established by planetesimal volatile evaporation
Earth’s volatile element content was established largely by volatile evaporation from molten planetesimals before Earth’s formation, according to first-principles calculations and examination of sulfur isotope fractionation.
- Wenzhong Wang
- , Chun-Hui Li
- & Shui-Jiong Wang
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Matters Arising |
Reply to: No 182W evidence for early Moon formation
- Maxwell Marzban Thiemens
- , Jonas Tusch
- & Carsten Münker
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Article |
Dynamic history of the inner core constrained by seismic anisotropy
The inner core underwent preferential equatorial growth and translation after nucleation ~0.5–1.5 billion years ago, according to an analysis of its seismic anisotropy and self-consistent geodynamic simulations.
- Daniel A. Frost
- , Marine Lasbleis
- & Barbara Romanowicz
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Article |
Rates of protoplanetary accretion and differentiation set nitrogen budget of rocky planets
Rates of protoplanetary accretion and differentiation control the depletion of nitrogen in rocky planets, according to high-pressure/temperature experiments that show that nitrogen is extremely siderophilic.
- Damanveer S. Grewal
- , Rajdeep Dasgupta
- & Alexandra Farnell
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Article |
Superionic iron oxide–hydroxide in Earth’s deep mantle
Under conditions of Earth’s deep lower mantle, hydrogen ions diffuse freely through the FeOOH lattice framework and electrical conductivity increases rapidly, according to electrical conductivity experiments and first-principles simulations.
- Mingqiang Hou
- , Yu He
- & Ho-Kwang Mao
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Article |
Heavy iron isotope composition of iron meteorites explained by core crystallization
Experiments show that the iron isotopic composition of iron meteorites can be explained by core crystallization, and suggest the presence of sulfur-rich core material that remains unsampled by meteorite collections.
- Peng Ni
- , Nancy L. Chabot
- & Anat Shahar
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Article |
Weak magnetic field changes over the Pacific due to high conductance in lowermost mantle
High conductance in the lowermost mantle beneath the Pacific deflects the planetary gyre, which results in limited variation in the magnetic field in the region, according to numerical modelling of Earth’s core dynamics.
- Mathieu Dumberry
- & Colin More
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Article |
The Earth’s core as a reservoir of water
The Earth’s core may host most of the planet’s water inventory, according to calculations of the partitioning behaviour of water at conditions of core formation.
- Yunguo Li
- , Lidunka Vočadlo
- & John P. Brodholt
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Article |
Recent north magnetic pole acceleration towards Siberia caused by flux lobe elongation
Observation-based modelling suggests that recent acceleration of Earth’s north magnetic pole towards Siberia can be linked to elongation of a lobe of negative magnetic flux at the core–mantle boundary beneath Canada.
- Philip W. Livermore
- , Christopher C. Finlay
- & Matthew Bayliff
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Article |
Iron isotope fractionation at the core–mantle boundary by thermodiffusion
Iron isotopic fractionation at the core–mantle boundary due to thermal diffusion may partly explain the iron isotope composition of the upper mantle, according to high-temperature experiments and numerical simulations.
- Charles E. Lesher
- , Juliane Dannberg
- & James M. Brenan
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Article |
Crustal and time-varying magnetic fields at the InSight landing site on Mars
The magnetic field measured by the InSight lander on Mars varies daily and is ten times stronger than expected. The field is inferred to originate from components of basement rocks magnetized by an ancient dynamo of Earth-like strength.
- Catherine L. Johnson
- , Anna Mittelholz
- & William B. Banerdt
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Article |
Regional stratification at the top of Earth's core due to core–mantle boundary heat flux variations
Stratification of the Earth’s outer core is regional, not global, and created by lateral heat flux variations at the core–mantle boundary, according to numerical simulations of fluid core dynamics
- Jon Mound
- , Chris Davies
- & Jon Aurnou
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Article |
Earth’s volatile element depletion pattern inherited from a carbonaceous chondrite-like source
Earth’s volatile element composition can be explained without exotic building blocks or late volatile loss, according to matching patterns of volatile element depletion for Earth and carbonaceous chondrites, as revealed by chondrite analyses.
- Ninja Braukmüller
- , Frank Wombacher
- & Carsten Münker
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Article |
Geomagnetic jerks and rapid hydromagnetic waves focusing at Earth’s core surface
Geomagnetic jerks in the Earth’s magnetic field are caused by the arrival of hydromagnetic waves and could be generated by sudden releases of buoyancy in the Earth’s core, suggest geodynamic numerical model simulations.
- Julien Aubert
- & Christopher C. Finlay
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News & Views |
Geodynamo recharged
Transition from a weak and erratic geomagnetic field to a more stable one around 560 million years ago, inferred from palaeomagnetic measurements, suggests that the inner core may have solidified around that time, much later than thought.
- Peter Driscoll
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Article |
Young inner core inferred from Ediacaran ultra-low geomagnetic field intensity
A late onset of inner-core growth is inferred from ultra-low palaeomagnetic field strengths about 565 million years ago, as measured in magnetic inclusions in Ediacaran crystals.
- Richard K. Bono
- , John A. Tarduno
- & Rory D. Cottrell
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Article |
Oxidized conditions in iron meteorite parent bodies
Some iron meteorite parent bodies may have formed beyond Mars under oxidizing conditions, according to analyses of chromium isotopes.
- P. Bonnand
- & A. N. Halliday
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Article |
Heterogeneous delivery of silicate and metal to the Earth by large planetesimals
Collisions of large differentiated impactors during the late stages of Earth’s accretion may have heterogeneously mixed projectile material into the Earth, explaining observed chemical and isotopic heterogeneities in mantle materials.
- S. Marchi
- , R. M. Canup
- & R. J. Walker
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Article |
Silicate Earth’s missing niobium may have been sequestered into asteroidal cores
Niobium may be sequestered into the cores of some asteroids rather than remaining in their mantles according to measurements of meteorites and partitioning experiments. Accretion of such asteroids may explain why Earth’s mantle is depleted in niobium.
- Carsten Münker
- , Raúl O. C. Fonseca
- & Toni Schulz
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Editorial |
To probe a core
Hidden under many kilometres of silicate mantle material, the cores of Earth and other planets are hard to investigate. The Psyche spacecraft, designed to visit a metal body that may be a core stripped of its mantle, could bring a close-up view.
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News & Views |
A nickel for your planet's thoughts
Variability of iron isotopes among planetary bodies may reflect their accretion or differentiation histories. Experiments suggest nickel may be the ingredient controlling iron isotope signatures, supporting fractionation during core formation.
- Paolo A. Sossi
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Article |
Non-chondritic iron isotope ratios in planetary mantles as a result of core formation
Planetary materials reveal variation in iron isotope composition across planetary bodies. Experiments suggest that this variation can be explained by varying degrees of fractionation during core formation, depending on temperature.
- Stephen M. Elardo
- & Anat Shahar
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Article |
Stabilization of body-centred cubic iron under inner-core conditions
The crystal structure of iron under the extreme pressures and temperatures of Earth’s core is debated. Numerical simulations suggest that the body-centred cubic structure of iron is stable under inner-core conditions.
- Anatoly B. Belonoshko
- , Timofei Lukinov
- & Sergei I. Simak
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Article |
An accelerating high-latitude jet in Earth’s core
Satellite observations have detected localized magnetic field changes at high latitudes. Simulations suggest these changes can be explained by a westward jet in the liquid core, which has been accelerating over the past 15 years.
- Philip W. Livermore
- , Rainer Hollerbach
- & Christopher C. Finlay
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News & Views |
Stratified by a sunken impactor
There is potential evidence for a stratified layer at the top of the Earth's core, but its origin is not well understood. Laboratory experiments suggest that the stratified layer could be a sunken remnant of the giant impact that formed the Moon.
- Miki Nakajima
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Letter |
Core merging and stratification following giant impact
The Earth’s outermost core is thought to be stratified. Turbulent mixing experiments suggest that merging between the cores of projectile and planet following the Moon-forming giant impact could have produced the stratification.
- Maylis Landeau
- , Peter Olson
- & Benjamin H. Hirsh
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Letter |
Carbon and sulfur budget of the silicate Earth explained by accretion of differentiated planetary embryos
The carbon abundance in the Earth’s mantle is enhanced relative to sulfur. Experiments suggest that the accretion of a differentiated planetary body to the growing Earth could explain the silicate Earth’s carbon and sulfur budgets.
- Yuan Li
- , Rajdeep Dasgupta
- & Nobumichi Shimizu
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Review Article |
Constraints from material properties on the dynamics and evolution of Earth’s core
The material properties of the Earth’s core have been better constrained by recent technical and computational advances. The properties imply that the core was once hot, but is cooling quickly, and the inner core is young.
- Christopher Davies
- , Monica Pozzo
- & Dario Alfè
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News & Views |
Iron fog of accretion
Pinpointing when Earth's core formed depends on the extent of metal–silicate equilibration in the mantle. Vaporization and recondensation of impacting planetesimal cores during accretion may reconcile disparate lines of evidence.
- William W. Anderson
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Letter |
Impact vaporization of planetesimal cores in the late stages of planet formation
Differentiated planetesimals may have delivered iron-rich material to Earth in giant impacts at the end of accretion. Impact experiments suggest that the planetesimals’ iron cores vaporized, aiding dispersal and mixing into Earth’s mantle.
- Richard G. Kraus
- , Seth Root
- & Thomas R. Mattsson
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Letter |
High Poisson's ratio of Earth's inner core explained by carbon alloying
Earth’s core exhibits similar elastic properties to rubber. Experiments show that a high-pressure phase of iron carbide modifies iron’s elastic properties under inner-core conditions, suggesting that carbon is the light element in the core.
- C. Prescher
- , L. Dubrovinsky
- & M. Hanfland
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Letter |
Equatorial anisotropy in the inner part of Earth’s inner core from autocorrelation of earthquake coda
The speed of seismic waves passing through the Earth’s inner core varies with direction. Analysis of earthquake seismic data suggests that this directional dependence differs between innermost and outer inner core.
- Tao Wang
- , Xiaodong Song
- & Han H. Xia
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Letter |
Strong tidal heating in an ultralow-viscosity zone at the core–mantle boundary of the Moon
Tidal dissipation in the Moon depends on the lunar tidal period. Numerical modelling of the Moon’s response to tidal forces suggests that tidal dissipation is localized in an ultralow-viscosity zone at the core–mantle boundary.
- Yuji Harada
- , Sander Goossens
- & Junichi Haruyama
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Letter |
Redox control of the fractionation of niobium and tantalum during planetary accretion and core formation
The ratio of the refractory lithophile elements niobium and tantalum in the silicate Earth is anomalously low. Partitioning experiments suggest that the ratio of these elements is controlled by oxygen fugacity, and thus can be used to constrain the redox conditions of planetary accretion and core formation.
- Camille Cartier
- , Tahar Hammouda
- & Jean-Luc Devidal
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Letter |
Formation of an interconnected network of iron melt at Earth’s lower mantle conditions
The differentiation of the Earth into mantle and core implies that there is a mechanism to separate iron from silicates. Three-dimensional imaging of samples experimentally subjected to high pressures reveals that liquid iron forms interconnected melt networks at lower mantle conditions, suggesting pathways through which iron can percolate towards the core.
- Crystal Y. Shi
- , Li Zhang
- & Wendy L. Mao
A hydrogen-enriched layer in the topmost outer core sourced from deeply subducted water
Patching up the field
Water and the lunar dynamo
Saving sulphur
Mantle-driven magnetic field?