Palaeomagnetic field intensity variations suggest Mesoproterozoic inner-core nucleation

  title={Palaeomagnetic field intensity variations suggest Mesoproterozoic inner-core nucleation},
  author={Andrew J. Biggin and Elisa J. Piispa and Lauri J. Pesonen and Richard Holme and Greig A. Paterson and Toni Veikkolainen and Lisa Tauxe},
The Earth’s inner core grows by the freezing of liquid iron at its surface. The point in history at which this process initiated marks a step-change in the thermal evolution of the planet. Recent computational and experimental studies have presented radically differing estimates of the thermal conductivity of the Earth’s core, resulting in estimates of the timing of inner-core nucleation ranging from less than half a billion to nearly two billion years ago. Recent inner-core nucleation (high… 
First palaeointensity data from the cryogenian and their potential implications for inner core nucleation age
The timing of inner core nucleation is a hugely significant event in Earth's evolution and has been the subject of intense debate. Some of the most recent theoretical estimates for the age of
The signature of inner-core nucleation on the geodynamo
Abstract Energy considerations indicate that the power delivered to the present-day geodynamo comes mainly from the growth of the solid inner core, through light element and latent heat releases. The
Powering Earth’s dynamo with magnesium precipitation from the core
It is shown that the precipitation of magnesium-bearing minerals from the core could have served as an alternative power source and that Earth’s dynamo would survive throughout geologic time even if core radiogenic heating were minimal and core cooling were slow.
Palaeointensity of the 1.3 billion-yr-old Gardar basalts, southern Greenland revisited: no evidence for onset of inner core growth
The age of the inner core nucleation is a first-order problem in the thermal evolution of the Earth that can be addressed with palaeomagnetism. We conducted a palaeointensity study on the 1.3 Ga
Young inner core inferred from Ediacaran ultra-low geomagnetic field intensity
An enduring mystery about Earth has been the age of its solid inner core. Plausible yet contrasting core thermal conductivity values lead to inner core growth initiation ages that span 2 billion
Simulating 2 Ga of geodynamo history
The paleomagnetic record indicates the geodynamo has been active over much of Earth history with surprisingly little trend in paleointensity. Variability, however, is expected from models that
Thermal evolution of Earth with magnesium precipitation in the core
Vigorous convection in Earth's core powers our global magnetic field, which has survived for over three billion years. In this study, we calculate the rate of entropy production available to drive
Pallasite paleomagnetism: Quiescence of a core dynamo
Recent paleomagnetic studies of two Main Group pallasites, the Imilac and Esquel, have found evidence for a strong, late-stage magnetic field on the parent body. It has been hypothesized that this
The Fate of Liquids Trapped During the Earth's Inner Core Growth
The growth history of the inner core is inherently linked to the thermal history of the Earth. The crystallization of the inner core may have been delayed by supercooling, and went through an initial
The deep Earth may not be cooling down
Abstract The Earth is a thermal engine generating the fundamental processes of geomagnetic field, plate tectonics and volcanism. Large amounts of heat are permanently lost at the surface yielding the


Long-term evolution of the geomagnetic dipole moment
Abstract The geomagnetic field intensity measured at the surface of the planet is a potential indicator of the dynamo activity in the conducting liquid core of the Earth. Rapid field variations must
Modelling the palaeo-evolution of the geodynamo
Although it is known that the geodynamo has been operating for at least 3.2 Ga, it remains difficult to infer the intensity, dipolarity and stability (occurrence of reversals) of the Precam-brian
Possible links between long-term geomagnetic variations and whole-mantle convection processes
The Earth's internal magnetic field varies on timescales of months to billions of years. The field is generated by convection in the liquid outer core, which in turn is influenced by the heat flowing
Evidence for a very-long-term trend in geomagnetic secular variation
Reconstructions of palaeosecular variation suggest that the Earth’s magnetic field reversed less frequently 2.82 to 2.45 billion years ago, relative to the Cenozoic era. This suggests a long-term
Thermal and electrical conductivity of iron at Earth’s core conditions
New estimates indicate that the adiabatic heat flux is 15 to 16 terawatts at the CMB, higher than present estimates of CMB heat flux based on mantle convection; the top of the coremust be thermally stratified and any convection in the upper core must be driven by chemical convection against the adverse thermal buoyancy or lateral variations in CMBHeat flow.
Intensity of the Earth's magnetic field since Precambrian from Thellier-type palaeointensity data and inferences on the thermal history of the core
SUMMARY We present a compilation of palaeointensity data obtained by the Thellier method from magmatic rocks up to 3.5 Gyr old. No apparent very long-term variation occurs from present to Early
Time variations in geomagnetic intensity
[1] After many years spent by paleomagnetists studying the directional behavior of the Earth’s magnetic field at all possible timescales, detailed measurements of field intensity are now needed to
Thermochemical remanent magnetization in Precambrian rocks: Are we sure the geomagnetic field was weak?
[1] Thellier paleointensity determinations from two dikes of the Early Proterozoic (∼2.46 Ga) Matachewan dike swarm (Canada) yield field values of 2.14 ± 0.18 and 9.81 ± 1.65 μT. Corresponding values
Geomagnetic dipole strength and reversal rate over the past two million years
It is shown that, at least during this period, the time-averaged field was higher during periods without reversals but the amplitude of the short-term oscillations remained the same, and few intervals of very low intensity are expected during periods with a strong average dipole moment, whereas more excursions and reversals areexpected during periods of weak field intensity.
Instability of thermoremanence and the problem of estimating the ancient geomagnetic field strength from non-single-domain recorders
  • R. Shaar, L. Tauxe
  • Geography, Medicine
    Proceedings of the National Academy of Sciences
  • 2015
It is demonstrated the possibility that much of available paleointensity data could be biased by instability of thermoremanent magnetization (TRM) associated with non-single-domain (SD) particles.