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| Titel |
The 10Be isotopic signature of the Brunhes/Matuyama field reversal from marine sediments |
| VerfasserIn |
Johannes Lachner, Marcus Christl |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250043625
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| Zusammenfassung |
| Marine sediments can be used to reconstruct 10Be production changes, which are mainly
caused by variations of the geomagnetic field strength. Here we use the so called authigenic
10Be/9Be ratio as a proxy for geomagnetic paleointensity. With a constant flux tracer (230Th)
the 10Be flux to the sea floor can be estimated. But this method is limited to about 350 kyrs
by the lifetime of 230Th, whereas 9Be-normalization can be applied to reconstruct the relative
variation of the geomagnetic field beyond the possibilities of Th-normalization.
A global signature of a magnetic field reversial or an excursion in the 10Be/9Be
ratio can be used to link the chronologies of ice cores with marine and terrestrial
sediments.
A novel method to directly measure the natural 10Be/9Be ratio with low energy
Accelerator Mass Spectrometry (AMS) at the compact accelerator Tandy (600 kV) is applied.
This method simplifies the determination of the 10Be/9Be ratio in natural samples, because
only a single measurement is necessary. With this technique of carrier-free AMS on a small
machine a highly resolved data record in a time range 70 ka around the field reversal in up to
1 ka resolution was recorded around the expected maximum according to the magnetic
inclination data.
Five locations distributed in the Indic, Pacific and Atlantic at different latitudes have been
chosen for sampling and determination of the authigenic 10Be/9Be ratio. First data from these
cores in the time range of the Brunhes-Matuyama field reversion will be presented. |
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