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Enhanced inner core fine-scale heterogeneity towards Earth’s centre
We create a three-dimensional model of inner core fine-scale heterogeneity, showing that inner core scattering is ubiquitous and that it substantially increases in strength 500–800 km beneath the inner core boundary.
- Guanning Pang
- , Keith D. Koper
- & Garrett Euler
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Article
| Open AccessHadaean to Palaeoarchaean stagnant-lid tectonics revealed by zircon magnetism
Magnetic palaeointensity data from the Barberton Greenstone Belt (South Africa) as well as the Jack Hills (Western Australia) show nearly constant palaeofield values between 3.9 Ga and 3.4 Ga, providing evidence for stagnant-lid mantle convection.
- John A. Tarduno
- , Rory D. Cottrell
- & Gautam Mitra
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Article |
Core origin of seismic velocity anomalies at Earth’s core–mantle boundary
Investigations of the crystallization of FeSi in Fe–Si–H melt under high pressure−temperature conditions provide evidence of a new process that explains geochemical and geophysical observations at the core–mantle boundary.
- Suyu Fu
- , Stella Chariton
- & Sang-Heon Shim
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Letter |
Turbulent convective length scale in planetary cores
Numerical modelling of rotating turbulent convective flows shows that the length scale of convection in planetary cores is set by the flow speed and not by the fluid viscosity.
- Céline Guervilly
- , Philippe Cardin
- & Nathanaël Schaeffer
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Letter |
A complex dynamo inferred from the hemispheric dichotomy of Jupiter’s magnetic field
Maps of Jupiter’s internal magnetic field at a range of depths reveal an unusual morphology, suggesting that Jupiter’s dynamo, unlike Earth’s, does not operate in a thick, homogeneous shell.
- Kimberly M. Moore
- , Rakesh K. Yadav
- & Steven M. Levin
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Letter |
Early episodes of high-pressure core formation preserved in plume mantle
Xenon isotopic anomalies found in modern plume rocks are explained as the result of iodine-to-plutonium fractionations during early, high-pressure episodes of core formation.
- Colin R. M. Jackson
- , Neil R. Bennett
- & Yingwei Fei
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Letter |
Crystallization of silicon dioxide and compositional evolution of the Earth’s core
Melting experiments with liquid Fe–Si–O alloy at the pressure of the Earth’s core reveal that the crystallization of silicon dioxide leads to core convection and a dynamo.
- Kei Hirose
- , Guillaume Morard
- & Stéphane Labrosse
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Letter |
Magnetic reversals from planetary dynamo waves
Polarity reversals caused by dynamo waves are demonstrated in a magnetohydrodynamic model that is relevant to planetary cores, suggesting a possible mechanism of geomagnetic reversals.
- Andrey Sheyko
- , Christopher C. Finlay
- & Andrew Jackson
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Letter |
A partially differentiated interior for (1) Ceres deduced from its gravity field and shape
Gravity and shape measurements for Ceres obtained from the Dawn spacecraft mission show that it is in hydrostatic equilibrium with its inferred normalized mean moment of inertia of 0.37, suggesting that Ceres has a rocky chondritic core overlaid by a volatile-rich icy shell.
- R. S. Park
- , A. S. Konopliv
- & F. Preusker
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Letter |
An early geodynamo driven by exsolution of mantle components from Earth’s core
Experiments show that magnesium oxide can dissolve in core-forming metallic melts at very high temperatures; core formation models suggest that a giant impact during Earth’s accretion could have contributed large amounts of magnesium to the early core, the subsequent exsolution of which would have generated enough gravitational energy to power an early geodynamo and produce an ancient magnetic field.
- James Badro
- , Julien Siebert
- & Francis Nimmo
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Letter |
Direct measurement of thermal conductivity in solid iron at planetary core conditions
The thermal conductivity of solid iron at the pressure and temperature conditions that prevail in the cores of planets is measured directly using a dynamically laser-heated diamond-anvil cell, yielding values that support findings from ancient magnetized rocks that suggest Earth’s magnetic field has persisted since the Earth’s earliest history.
- Zuzana Konôpková
- , R. Stewart McWilliams
- & Alexander F. Goncharov
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Letter |
Powering Earth’s dynamo with magnesium precipitation from the core
The thermal conductivity of iron is now known to be much larger than had been thought, implying that thermal convection and radiogenic heating would not have been enough to sustain the Earth’s geodynamo; here it is shown that the precipitation of magnesium-bearing minerals from the core could have served as the required power source.
- Joseph G. O’Rourke
- & David J. Stevenson
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Letter |
Palaeomagnetic field intensity variations suggest Mesoproterozoic inner-core nucleation
Analysis of a database of Precambrian palaeomagnetic intensity measurements reveals a clear transition in the Earth’s magnetic field that is probably the signature of the inner core first forming, suggesting a modest value of core thermal conductivity and supporting a simple thermal evolution model for the Earth.
- A. J. Biggin
- , E. J. Piispa
- & L. Tauxe
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Letter |
Long-lived magnetism from solidification-driven convection on the pallasite parent body
Nanomagnetic imaging has been used to obtain a palaeomagnetic time series of two pallasite meteorites, revealing that their convection was driven by core solidification, which would have caused long-lived magnetic fields in the cores of early Solar System planetary bodies.
- James F. J. Bryson
- , Claire I. O. Nichols
- & Richard J. Harrison
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Letter |
Geomagnetic fluctuations reveal stable stratification at the top of the Earth’s core
MAC waves (arising from magnetic, Archimedes and Coriolis forces) in the liquid core indicate a 140-kilometre-thick stratified layer on top of the Earth’s core and account for the 60-year geomagnetic fluctuations observed in the Earth’s geomagnetic field.
- Bruce Buffett
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Letter |
Bottom-up control of geomagnetic secular variation by the Earth’s inner core
The pattern of geomagnetic secular variation observed on the Earth’s surface is shown to be reproduced by two mechanisms relying on the inner core; this bottom-up heterogeneous driving of outer-core convection dominates top-down driving from mantle thermal heterogeneities.
- Julien Aubert
- , Christopher C. Finlay
- & Alexandre Fournier
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Letter |
Solid–liquid iron partitioning in Earth’s deep mantle
Iron in partially molten rocks under deep-mantle conditions partitions into the melt phase less than previously reported, suggesting that melt generated near the core–mantle boundary should segregate upwards.
- Denis Andrault
- , Sylvain Petitgirard
- & Mohamed Mezouar
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Letter |
Thermal and electrical conductivity of iron at Earth’s core conditions
First principles calculations of the thermal and electrical conductivities of liquid iron mixtures under Earth's core conditions suggest a relatively high adiabatic heat flux of 15 to16 terawatts at the core–mantle boundary, indicating that the top of the core must be thermally stratified.
- Monica Pozzo
- , Chris Davies
- & Dario Alfè
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News & Views |
A deep foundry
Melting and solidification of iron alloys in Earth's core may explain structural complexity in the solid inner core, and alter the way we think about the dynamics of the deep interior. See Letter p.361
- Bruce Buffett
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Letter |
Triggering of New Madrid seismicity by late-Pleistocene erosion
These authors argue that the concentration of magnitude-7 or larger earthquakes in the New Madrid seismic zone since the end of the last ice age results from the recent, climate-controlled, erosional history of the northern Mississippi embayment. They show that the upward flexure of the lithosphere caused a reduction of normal stresses in the upper crust sufficient to unclamp pre-existing faults close to failure equilibrium.
- E. Calais
- , A. M. Freed
- & S. Stein
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Letter |
Striations, duration, migration and tidal response in deep tremor
Deep seismic tremor in subduction zones has been suggested to repeat at a regular interval, migrate at various velocities and be modulated by tidal stress. Here, evidence is presented that a time-invariant interface property — possibly the ratio of brittle to ductile areas — controls tremor behaviour in the Nankai subduction zone, Japan. Where tremor duration is short, tremor is more strongly affected by tidal stress and migration is inhibited. Where tremor lasts longer, diffusive migration occurs with a constant diffusivity.
- Satoshi Ide
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News & Views |
Driving Earth's surface motions
Density variations within Earth's mantle may be a significant driver of both horizontal and vertical surface movements. The fingerprints of such mantle processes have been found in the Mediterranean region.
- Rinus Wortel
- & Rob Govers
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News & Views |
Mountains without erosion
Increased erosion associated with the rise of the world's great mountain ranges has been held to be the cause of a prolonged episode of past climate cooling. That connection is now brought into doubt.
- Yves Goddéris
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News & Views |
A new turn for Earth's rotation
Earth's spin rate varies with time. A six-year periodic signal in the planet's core is partly responsible, and increases the interior magnetic-field strength to much higher levels than previously thought.
- Andy Jackson