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

Early Cambrian renewal of the geodynamo and the origin of inner core structure

Paleomagnetism can elucidate the origin of inner core structure by establishing when crystallization started. The salient signal is an ultralow field strength, associated with waning thermal energy

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

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 gone through an initial



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.

Palaeosecular variation, field reversals and the stability of the geodynamo in the Precambrian

SUMMARY Palaeosecular variation (PSV), as estimated from the scatter of remanent magnetization directions or poles, can be used to shed light to processes in the geodynamo, and potentially, to model

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

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.