Evidence for an increase in cosmogenic 10Be during a geomagnetic reversal

  title={Evidence for an increase in cosmogenic 10Be during a geomagnetic reversal},
  author={Grant M. Raisbeck and Françoise Yiou and Didier L. Bourl{\`e}s and Dennis V. Kent},
Reversals in the geomagnetic field, which occur every few hundred thousand years, represent a dramatic change in the Earth's environment. Although there is no satisfactory theory for such reversals, it is generally accepted that the dipole field intensity decreases to <20% of its ‘normal’ value for a few thousand years during the change in direction1. Because the galactic and solar cosmic rays which impinge on the Earth's atmosphere are charged, a significant fraction (about half) of them are… 

Deciphering records of geomagnetic reversals

The fidelity of the signal extracted from paleomagnetic records is discussed in detail and special attention is paid to their resolution with respect to the timing and mechanisms involved in the magnetization process.

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

Sedimentary records of relative paleointensity of the geomagnetic field: Theory and practice

Sediments have proved irresistible targets for attempts at determining the relative variations in the Earth's magnetic field because of the possibility of long and continuous sequences that are well


The normalization of the natural remanent magnetism to laboratory-induced remanence for discrete samples from the top 54 m of Hole 932A produces a pattern similar to the apparent variation of the

10Be evidence for the Matuyama–Brunhes geomagnetic reversal in the EPICA Dome C ice core

Evidence is presented for enhanced 10Be deposition in the ice at 3,160–3,170 m, which is interpreted as a result of the low dipole field strength during the Matuyama–Brunhes geomagnetic reversal, which occurred about 780,000 years ago and provides a crucial tie point between ice cores, marine cores and a radiometric timescale.

Use of 10Be to Predict Atmospheric 14C Variations during the Laschamp Excursion: High Sensitivity to Cosmogenic Isotope Production Calculations

The Laschamp excursion is a period of reduced geomagnetic field intensity occurring 40.7 ± 1.0 kyr ago. As a consequence, cosmogenic isotope production increased dramatically and its sensitivity to

Geomagnetic moment instability between 0.6 and 1.3 Ma from cosmonuclide evidence

The reliability of paleomagnetic records as proxies of the geomagnetic field intensity is still a matter of controversy since volcanic materials hardly provide continuous records, and marine

Disentangling magnetic and environmental signatures of sedimentary 10Be/9Be records




Reversals of the Earth's magnetic field and climatic changes

IT has been suggested that evolution may be influenced by reversals of the Earth's magnetic field1–3. It was observed that there were correlations between discontinuities in microfossil assemblages

Faunal Extinctions and Reversals of the Earth's Magnetic Field

A study of 28 deep-sea piston cores from high and low latitudes shows that during the last 2.5 m.y. eight species of Radiolaria became extinct. Prior to their extinction these species were widely

Beryllium in the water column of the central North Pacific

The existence of the cosmogenic radioisotope of beryllium, 10Be(t1/2 = 1.5 Myr), was first confirmed1,2 almost 25 yr ago. Subsequently, Merrill et al.3 worked out the sedimentary geochemistry of the

Secular variations in the production of cosmogenic isotopes in the Earth's atmosphere

The dependence of cosmogenic isotope production on solar modulation and on geomagnetic field intensity has been calculated, and spallation yields based on the Silberberg-Tsao formalism have been

Paleomagnetic Study of Antarctic Deep-Sea Cores

It is concluded that paleomagnetic stratigraphy is a unique method for correlating and dating deep sea cores, and that future work with such cores may provide a complete or nearly complete record of the history of the earth's magnetic field beyond 4 million years.

Geomagnetic excursions and their paleomagnetic record

The paleomagnetic record of recent lake and marine sediments contains anomalous magnetic directions which have been interpreted as large-scale fluctuations of the geomagnetic field (excursions). In

A search in a marine sediment core for 10Be concentration variations during a geomagnetic field reversal

A search has been made for variations in the 10Be concentration in a North Pacific marine sediment core during the period of a geomagnetic reversal. The 10Be was counted directly using an accelerator

A detailed record of the Lower Jaramillo Polarity Transition from a southern hemisphere, deep‐sea sediment core

A detailed record of the lower Jaramillo (reversed to normal) polarity transition was obtained from a southern hemisphere, deep-sea sediment core (latitude = 35.91°E, longitude = 59.97°E) The record