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| Titel |
A high temporal resolution study of Holocene palaeomagnetic directions and intensity: assessing the reliability of a Swedish geomagnetic field reconstruction |
| VerfasserIn |
T. Stanton, I. Snowball, R. Muscheler, A. Nilsson, P. Riisager, M. F. Knudsen, T. Thordarson  , P. Reid |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250071098
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| Zusammenfassung |
| In order to better understand the temporal and spatial dynamics of the geomagnetic field,
reliable, high-quality, empirical palaeomagnetic data must be generated (Stanton et al.,
2011a). Records such as these allow us to: test models of geomagnetic behaviour; correlate
spatially separate sequences; and look at the effect of the Earth’s magnetic field on
cosmogenic nuclide production. The field can be recorded by magnetic minerals that
are present in geological archives, such as lavas, archaeomagnetic materials and
sediments.
This abstract is concerned with the results from the main author’s PhD studies (Stanton,
2011), which were primarily concerned with the palaeomagnetic signal recorded in four
overlapping core sediment sequences from an annually-laminated Holocene lake in Sweden:
Kälksjön. Annually-resolved archives allow the determination of high-resolution,
temporal, palaeomagnetic reconstructions, with a resolution generally higher than
those derived from lavas and archaeological archives, although the recorded values
are relative and not absolute. The Kälksjön sediments have proved a good archive
for recording geomagnetic field strength and direction, with an accurately dated,
high-resolution chronology (Stanton et al., 2010). The resulting measurements
showed a high level of correlation with other datasets in Fennoscandia (Stanton,
2011).
In another smaller study, an absolute palaeointensity curve was derived from a
number of Holocene Icelandic lava samples (Stanton et al., 2011b). Comparison
between this and the Kälksjön curve revealed similar long-term trends (Stanton,
2011).
Correlation between Kälksjön’s palaeointensity data and various proxies, however,
indicates that climatic conditions have affected the magnetic mineral assemblage in the
sequence, which in turn has biased the recorded palaeointensity signal. In order to verify
which of the palaeointensity features in the Kälksjön sequence could be deemed genuine, a
comparison of the low-pass filtered Kälksjön relative palaeointensity curve with
reconstructed 14C and 10Be geomagnetic field intensity data was made (Stanton et al.,
2011a). The results indicated that – in particular – two main features could be considered real
and reliable.
References:
Stanton, T., Snowball, I., Zillén, L., Wastegård, S., 2010. Validating a Swedish varve
chronology using radiocarbon, palaeomagnetic secular variation, lead pollution history and
statistical correlation. Quaternary Geochronology 5, 611–624.
Stanton, T., 2011. High temporal resolution reconstructions of Holocene palaeomagnetic
directions and intensity: an assessment of geochronology, feature reliability and
environmental bias. LUNDQUA (PhD) Thesis 63. Lund University, Sweden. ISBN:
978-91-86746-67-4.
Stanton, T., Nilsson, A., Snowball, I., Muscheler, R., 2011a. Assessing the reliability of
Holocene relative palaeointensity estimates: a case study from Swedish varved lake
sediments. Geophysical Journal International 187, 1195–1214.
Stanton, T., Riisager, P., Knudsen, M.F., Thordarson, T., 2011b. New palaeointensity data
from Holocene Icelandic lavas. Physics of the Earth and Planetary Interiors 186, 1–10. |
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