Mono Lake or Laschamp geomagnetic event recorded from lava flows in Amsterdam Island (southeastern Indian Ocean)
We report a survey carried out on basalt flows from Amsterdam Island in order to check the presence of intermediate directions interpreted to belong to a geomagnetic field excursion within the Brunhes epoch, completing this paleomagnetic record with paleointensity determinations and radiometric dati...
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ftdatacite:10.48550/arxiv.physics/0304061 2023-05-15T13:22:27+02:00 Mono Lake or Laschamp geomagnetic event recorded from lava flows in Amsterdam Island (southeastern Indian Ocean) Carvallo, Claire Camps, Pierre Ruffet, Gilles Henry, Bernard Poidras, Thierry 2003 https://dx.doi.org/10.48550/arxiv.physics/0304061 https://arxiv.org/abs/physics/0304061 unknown arXiv https://dx.doi.org/10.1046/j.1365-246x.2003.01993.x Assumed arXiv.org perpetual, non-exclusive license to distribute this article for submissions made before January 2004 http://arxiv.org/licenses/assumed-1991-2003/ Geophysics physics.geo-ph FOS Physical sciences article-journal Article ScholarlyArticle Text 2003 ftdatacite https://doi.org/10.48550/arxiv.physics/0304061 https://doi.org/10.1046/j.1365-246x.2003.01993.x 2022-04-01T16:28:39Z We report a survey carried out on basalt flows from Amsterdam Island in order to check the presence of intermediate directions interpreted to belong to a geomagnetic field excursion within the Brunhes epoch, completing this paleomagnetic record with paleointensity determinations and radiometric dating. The directional results corroborate the findings by Watkins and Nougier (1973) : normal polarity is found for two units and an intermediate direction, with associated VGPs close to the equator, for the other two units. A notable result is that these volcanic rocks are well suited for absolute paleointensity determinations. Fifty percent of the samples yields reliable intensity values with high quality factors. An original element of this study is that we made use of the PTRM-tail test of Shcherbakova et al. (2000) to help in the interpretation of the paleointensity measurements. Doing thus, only the high temperature intervals, beyond 400 degres C, were retained to obtain the most reliable estimate of the strength of the ancient magnetic field. The normal units yield Virtual Dipole Moments (VDM) of 6.2 and 7.7 10e22 Am2 and the excursional units yield values of 3.7 and 3.4 10e22 Am2. These results are quite consistent with the other Thellier determinations from Brunhes excursion records, all characterized by a decrease of the VDM as VGP latitude decreases. 40Ar/39Ar isotopic age determinations provide an estimate of 26+-15 Kyr and 18+-9 Kyr for the transitional lava flows, which could correspond to the Mono Lake excursion. However, the large error bars associated with these ages do not exclude the hypothesis that this event is the Laschamp. Text Amsterdam Island DataCite Metadata Store (German National Library of Science and Technology) Indian Watkins ENVELOPE(-67.086,-67.086,-66.354,-66.354) Shcherbakova ENVELOPE(10.533,10.533,-71.833,-71.833) |
institution |
Open Polar |
collection |
DataCite Metadata Store (German National Library of Science and Technology) |
op_collection_id |
ftdatacite |
language |
unknown |
topic |
Geophysics physics.geo-ph FOS Physical sciences |
spellingShingle |
Geophysics physics.geo-ph FOS Physical sciences Carvallo, Claire Camps, Pierre Ruffet, Gilles Henry, Bernard Poidras, Thierry Mono Lake or Laschamp geomagnetic event recorded from lava flows in Amsterdam Island (southeastern Indian Ocean) |
topic_facet |
Geophysics physics.geo-ph FOS Physical sciences |
description |
We report a survey carried out on basalt flows from Amsterdam Island in order to check the presence of intermediate directions interpreted to belong to a geomagnetic field excursion within the Brunhes epoch, completing this paleomagnetic record with paleointensity determinations and radiometric dating. The directional results corroborate the findings by Watkins and Nougier (1973) : normal polarity is found for two units and an intermediate direction, with associated VGPs close to the equator, for the other two units. A notable result is that these volcanic rocks are well suited for absolute paleointensity determinations. Fifty percent of the samples yields reliable intensity values with high quality factors. An original element of this study is that we made use of the PTRM-tail test of Shcherbakova et al. (2000) to help in the interpretation of the paleointensity measurements. Doing thus, only the high temperature intervals, beyond 400 degres C, were retained to obtain the most reliable estimate of the strength of the ancient magnetic field. The normal units yield Virtual Dipole Moments (VDM) of 6.2 and 7.7 10e22 Am2 and the excursional units yield values of 3.7 and 3.4 10e22 Am2. These results are quite consistent with the other Thellier determinations from Brunhes excursion records, all characterized by a decrease of the VDM as VGP latitude decreases. 40Ar/39Ar isotopic age determinations provide an estimate of 26+-15 Kyr and 18+-9 Kyr for the transitional lava flows, which could correspond to the Mono Lake excursion. However, the large error bars associated with these ages do not exclude the hypothesis that this event is the Laschamp. |
format |
Text |
author |
Carvallo, Claire Camps, Pierre Ruffet, Gilles Henry, Bernard Poidras, Thierry |
author_facet |
Carvallo, Claire Camps, Pierre Ruffet, Gilles Henry, Bernard Poidras, Thierry |
author_sort |
Carvallo, Claire |
title |
Mono Lake or Laschamp geomagnetic event recorded from lava flows in Amsterdam Island (southeastern Indian Ocean) |
title_short |
Mono Lake or Laschamp geomagnetic event recorded from lava flows in Amsterdam Island (southeastern Indian Ocean) |
title_full |
Mono Lake or Laschamp geomagnetic event recorded from lava flows in Amsterdam Island (southeastern Indian Ocean) |
title_fullStr |
Mono Lake or Laschamp geomagnetic event recorded from lava flows in Amsterdam Island (southeastern Indian Ocean) |
title_full_unstemmed |
Mono Lake or Laschamp geomagnetic event recorded from lava flows in Amsterdam Island (southeastern Indian Ocean) |
title_sort |
mono lake or laschamp geomagnetic event recorded from lava flows in amsterdam island (southeastern indian ocean) |
publisher |
arXiv |
publishDate |
2003 |
url |
https://dx.doi.org/10.48550/arxiv.physics/0304061 https://arxiv.org/abs/physics/0304061 |
long_lat |
ENVELOPE(-67.086,-67.086,-66.354,-66.354) ENVELOPE(10.533,10.533,-71.833,-71.833) |
geographic |
Indian Watkins Shcherbakova |
geographic_facet |
Indian Watkins Shcherbakova |
genre |
Amsterdam Island |
genre_facet |
Amsterdam Island |
op_relation |
https://dx.doi.org/10.1046/j.1365-246x.2003.01993.x |
op_rights |
Assumed arXiv.org perpetual, non-exclusive license to distribute this article for submissions made before January 2004 http://arxiv.org/licenses/assumed-1991-2003/ |
op_doi |
https://doi.org/10.48550/arxiv.physics/0304061 https://doi.org/10.1046/j.1365-246x.2003.01993.x |
_version_ |
1766365015139418112 |