Paleomagnetism and the Nature of the Geodynamo

  title={Paleomagnetism and the Nature of the Geodynamo},
  author={Ronald T. Merrill and P. L. Mcfadden},
  pages={345 - 350}
Records of direct observations of the earth's magnetic field cover less than a ten-millionth ofthe known lifetime of the field. Thus our knowledge of several geomagnetic phenomena, critical to our understanding of the geodynamo, must come firom the paleomagnetic record. A combination of substantial advances during the past decade or so both in dynamo theory (previously the domain of the mathematician) and in paleomagnetism (previously the domain of the geologist) has led to provocative models… 

Polarity transitions and excursions of the geomagnetic field

The nature of geomagnetic field behavior during polarity transitions is one of the most hotly debated issues in modern geophysics. Dynamo action in the earth's fluid outer core is known to be

Dynamo theory and paleomagnetism

For more than 200 years the origin of Earth's magnetic field was attributed to permanent magnetization. Even today no single argument (e.g., that Earth's deep interior is too hot to sustain permanent

Equilibrium in the Earth's

The Earth's magnetic field has reversed its polarity hundreds of times in the Earth's history. This phenomenon is generally viewed as due to a Poisson nonstationary process. Here, the geomagnetic

Long-lived transitional states of the geomagnetic field and the two dynamo families

Palaeomagnetic data from lavas produced at the Hawaii and Society Islands hotspots suggest that one or more specific, long-lived field configurations recur during successive polarity reversals

Geodynamo History Preserved in Single Silicate Crystals: Origins and Long-Term Mantle Control

The long-term history of the geodynamo provides insight into how Earth's innermost and outermost parts formed. The magnetic field is generated in the liquid-iron core as a result of convection driven

Geomagnetic polarity transitions

The top of Earth's liquid outer core is nearly 2900 km beneath Earth's surface, so we will never be able to observe it directly. This hot, dense, molten iron‐rich body is continuously in motion and

Chaos in geomagnetic reversal records : a comparison between Earth's magnetic field data and model disk dynamo data

The Earth's geomagnetic field reverses its polarity at irregular time intervals. However, it is not clear whether a reversal is a deterministic (low-dimensional) or a random (high-dimensional)

Preferred Bands of Longitude for Geomagnetic Reversal VGP Paths: Implications for Reversal Mechanisms

Different analysis of new records of recent polarity reversals and of many records published in the last years show a remarkable confinement of the transitional VGP’s to the longitudinal sector over

In search of high-fidelity geomagnetic paleointensities : A comparison of single plagioclase crystal and whole rock Thellier-Thellier analyses

The strength of Earth's magnetic field, on timescales greater than a million years, is known primarily from Thellier-Thellier analyses of igneous rocks. In the Thellier-Thellier method, the natural



Paleomagnetic records of geomagnetic field reversals and the morphology of the transitional fields

The reversal of polarity of the earth's magnetic field is one of the most remarkable features of our planet's magnetism. A proper documentation of reversal phenomena may therefore be expected to

Geomagnetic reversals from impacts on the Earth

The impact of a large extraterrestrial object on the Earth can produce a geomagnetic reversal through the following mechanism: dust from the impact crater and soot from fires trigger a climate change

The Paleomagnetic Field from Equatorial Deep-Sea Sediments: Axial Symmetry and Polarity Asymmetry

Paleomagnetic data from 89 equatorial deep-sea sediment cores indicate that the configuration of the time-averaged geomagnetic field depends strongly on polarity state but that it remains within 1

The frequency of geomagnetic reversals and the symmetry of the nondipole field

The average frequency of geomagnetic reversals seen through a sliding window 10 m.y. long typically remains constant or nearly so for intervals of the order of 5 × 107 years and then increases or

Polarity Transition Records and the Geomagnetic Dynamo

Comparison with the most detailed transitional VGP path records presently available gives some indication of the above behavior as predicted by the Parker-Levy model.

Determination of the intensity of the Earth's magnetic field during archaeological times: Reliability of the Thellier Technique

After indicating the basis of the technique, its use with a cryogenic SQUID magnetometer is outlined, particular emphasis being given to the need for stringent reliability criteria. Comparison of

Non-linear processes in the geodynamo: palaeomagnetic evidence

Summary. Palaeomagnetic data relating to secular variation, westward drift, non-dipole field scatter, field intensities and polarity transitions are considered together in an attempt to improve our

The westward drift of the Earth's magnetic field

The westward drift of the non-dipole part of the earth’s magnetic field and of its secular variation is investigated for the period 1907-45 and the uncertainty of the results discussed. It is found