Palaeointensities of the Auckland geomagnetic excursions by the LTD-DHT Shaw method
書誌事項
- 公開日
- 2006-02
- 権利情報
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- https://www.elsevier.com/tdm/userlicense/1.0/
- DOI
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- 10.1016/j.pepi.2005.09.005
- 公開者
- Elsevier BV
この論文をさがす
説明
Abstract We report new palaeointensity results concerning the Auckland geomagnetic excursions using the double heating technique of the Shaw method with low temperature demagnetisation (LTD-DHT Shaw method). The excursional palaeodirections recorded in six volcanoes of the Auckland volcanic field, New Zealand, have been classified into three groups: north-down (ND), west-up (WU) and south-up (SU) directions. In the present study, five to six consistent palaeointensities have been obtained from each of five volcanoes recording the Auckland geomagnetic excursions. The Wiri (27 ka), Crater Hill and Puketutu volcanoes (ND group) yielded mean palaeointensities of 10.6 ± 1.2 (1σ), 11.8 ± 2.8 and 11.1 ± 0.4 μT, respectively. The Hampton Park volcano (55 ka; WU group) gave 9.5 ± 1.2 μT while the McLennan Hills volcano (SU group) gave 2.5 ± 0.5 μT. It is notable that consistent palaeointensities have been obtained from the three different volcanoes which have almost the same palaeodirections (ND group), possibly supporting the reliability of the palaeointensity data. These five palaeointensities for the Auckland geomagnetic excursions correspond to virtual dipole moments (VDMs) of 0.6–2.1 × 1022 A m2, whereas three mean palaeointensities obtained from the Auckland volcanoes having non-excursional palaeodirections are 13.1–40.0 μT giving stronger VDMs of 2.1–6.9 × 1022 A m2. These results suggest that the dipole component of the geomagnetic field reduced to about 2 × 1022 A m2 or less during the Auckland geomagnetic excursions.
収録刊行物
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- Physics of the Earth and Planetary Interiors
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Physics of the Earth and Planetary Interiors 154 (2), 168-179, 2006-02
Elsevier BV
