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The detailed structure of geomagnetic excursions and their relation to cosmogenic nuclides, and climate variations

Objetivo

The primary scientific objectives of this project are twofold, 1) to improve understanding of the mechanisms which generate the geomagnetic field in the core by careful study of geomagnetic excursions (brief changes in direction and intensity of the geomagnetic field) and, 2) to better understand the correlation between geomagnetic-field intensity, production rate of cosmogenic nuclides, and climate variations.

This project will involve a detailed study of two such geomagnetic excursions, the Blake and the Jamaica, in three sediment cores at varying latitude. It will assess the exact magnetic-field behaviour during the excursions, in terms of direction, intensity, and duration. By combining already existing oxygen isotope stratigraphies for these cores with precise estimates of the sedimentation rates from 230Thxs measurements (an approach termed Th-normalization) the exact duration of these excursions will be constrained. Measurements of the flux of cosmogenic nuclides (10Be) to the sediments during the magnetic excursions will also be performed to assess the relationship between field intensity and cosmogenic production rates.

Th-normalization is required to calculate the exact fluxes of 10Be to the sediments, because the concentration of 10Be is dependent on sedimentation rate. As the project develops, absolute palaeointensities from lava flows will also be measured and combined with the relative palaeointensity from the sediments to construct a detailed record of the absolute palaeointensity for the last 100-200 kyr. This work will provide the first direct correlation of geomagnetic-field intensity with the production rate of cosmogenic nuclides, both measured in the same discrete samples. Furthermore, to investigate the relationship between the Earth's magnetic field and climate variations, the palaeointensity record obtained in this study will be compared with existing climate records from the Vostok ice-core.

Convocatoria de propuestas

FP6-2002-MOBILITY-5
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Coordinador

THE CHANCELLORS, MASTERS, AND SCHOLARS OF THE UNIVERSITY OF OXFORD
Aportación de la UE
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Dirección
University Offices, Wellington Square
OXFORD
Reino Unido

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Coste total
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