New paleointensity results from rapidly cooled Icelandic lavas: Implications for Arctic geomagnetic field strength
The Earth's magnetic field is assumed to be a geocentric axial dipole (GAD) when averaged over sufficient time (10(5)-10(6)years). Recent investigations of global paleosecular variation and time-averaged field behavior on million year timescales generally support a predominantly dipole field in...
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ftcdlib:qt97g6m038 2023-05-15T13:31:50+02:00 New paleointensity results from rapidly cooled Icelandic lavas: Implications for Arctic geomagnetic field strength Cromwell, Geoff Tauxe, Lisa Halldorsson, Saemi 2015-05-30 application/pdf http://www.escholarship.org/uc/item/97g6m038 english eng eScholarship, University of California qt97g6m038 http://www.escholarship.org/uc/item/97g6m038 Cromwell, Geoff; Tauxe, Lisa; & Halldorsson, Saemi. (2015). New paleointensity results from rapidly cooled Icelandic lavas: Implications for Arctic geomagnetic field strength. Journal of Geophysical Research, 120. UC San Diego: Retrieved from: http://www.escholarship.org/uc/item/97g6m038 Physical Sciences and Mathematics article 2015 ftcdlib 2016-04-02T19:20:19Z The Earth's magnetic field is assumed to be a geocentric axial dipole (GAD) when averaged over sufficient time (10(5)-10(6)years). Recent investigations of global paleosecular variation and time-averaged field behavior on million year timescales generally support a predominantly dipole field in the Northern Hemisphere, but unique field structures at high southern latitudes suggest the presence of a substantial (g) over bar (0)(2) quadrupolar component. Average paleointensity results from Antarctica are approximately half the value predicted by a GAD field; this behavior has not been sufficiently investigated because there is a paucity of absolute paleointensity data from the high latitudes of the Arctic and Antarctic, so no adequate comparisons have been made between the two regions. We collected glassy volcanic material from 129 subaerial and subglacial volcanic units in Iceland in order to provide a suitable intensity data set at high northern latitudes. Forty-four sites met our very strict specimen and site level selection criteria. Four Holocene sites have a median intensity value of 55.8 +/- 15.6 mu T (virtual axial dipole moment=78.1 +/- 22.0ZAm(2)), consistent with the present-day field. Thirty-seven sites are between 11ka and 3.35Ma with a median intensity of 33.1 +/- 8.3 mu T (47.0 +/- 11.6ZAm(2)). This median intensity is indistinguishable from some long-term global field strength estimates. Reevaluation of existing high-latitude data suggests a general agreement with our Iceland results, but there are still too few Antarctic sites to adequately compare Arctic and Antarctic field behaviors. Article in Journal/Newspaper Antarc* Antarctic Antarctica Arctic Arctic Iceland University of California: eScholarship Antarctic Arctic |
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English |
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Physical Sciences and Mathematics |
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Physical Sciences and Mathematics Cromwell, Geoff Tauxe, Lisa Halldorsson, Saemi New paleointensity results from rapidly cooled Icelandic lavas: Implications for Arctic geomagnetic field strength |
topic_facet |
Physical Sciences and Mathematics |
description |
The Earth's magnetic field is assumed to be a geocentric axial dipole (GAD) when averaged over sufficient time (10(5)-10(6)years). Recent investigations of global paleosecular variation and time-averaged field behavior on million year timescales generally support a predominantly dipole field in the Northern Hemisphere, but unique field structures at high southern latitudes suggest the presence of a substantial (g) over bar (0)(2) quadrupolar component. Average paleointensity results from Antarctica are approximately half the value predicted by a GAD field; this behavior has not been sufficiently investigated because there is a paucity of absolute paleointensity data from the high latitudes of the Arctic and Antarctic, so no adequate comparisons have been made between the two regions. We collected glassy volcanic material from 129 subaerial and subglacial volcanic units in Iceland in order to provide a suitable intensity data set at high northern latitudes. Forty-four sites met our very strict specimen and site level selection criteria. Four Holocene sites have a median intensity value of 55.8 +/- 15.6 mu T (virtual axial dipole moment=78.1 +/- 22.0ZAm(2)), consistent with the present-day field. Thirty-seven sites are between 11ka and 3.35Ma with a median intensity of 33.1 +/- 8.3 mu T (47.0 +/- 11.6ZAm(2)). This median intensity is indistinguishable from some long-term global field strength estimates. Reevaluation of existing high-latitude data suggests a general agreement with our Iceland results, but there are still too few Antarctic sites to adequately compare Arctic and Antarctic field behaviors. |
format |
Article in Journal/Newspaper |
author |
Cromwell, Geoff Tauxe, Lisa Halldorsson, Saemi |
author_facet |
Cromwell, Geoff Tauxe, Lisa Halldorsson, Saemi |
author_sort |
Cromwell, Geoff |
title |
New paleointensity results from rapidly cooled Icelandic lavas: Implications for Arctic geomagnetic field strength |
title_short |
New paleointensity results from rapidly cooled Icelandic lavas: Implications for Arctic geomagnetic field strength |
title_full |
New paleointensity results from rapidly cooled Icelandic lavas: Implications for Arctic geomagnetic field strength |
title_fullStr |
New paleointensity results from rapidly cooled Icelandic lavas: Implications for Arctic geomagnetic field strength |
title_full_unstemmed |
New paleointensity results from rapidly cooled Icelandic lavas: Implications for Arctic geomagnetic field strength |
title_sort |
new paleointensity results from rapidly cooled icelandic lavas: implications for arctic geomagnetic field strength |
publisher |
eScholarship, University of California |
publishDate |
2015 |
url |
http://www.escholarship.org/uc/item/97g6m038 |
geographic |
Antarctic Arctic |
geographic_facet |
Antarctic Arctic |
genre |
Antarc* Antarctic Antarctica Arctic Arctic Iceland |
genre_facet |
Antarc* Antarctic Antarctica Arctic Arctic Iceland |
op_source |
Cromwell, Geoff; Tauxe, Lisa; & Halldorsson, Saemi. (2015). New paleointensity results from rapidly cooled Icelandic lavas: Implications for Arctic geomagnetic field strength. Journal of Geophysical Research, 120. UC San Diego: Retrieved from: http://www.escholarship.org/uc/item/97g6m038 |
op_relation |
qt97g6m038 http://www.escholarship.org/uc/item/97g6m038 |
_version_ |
1766021159656095744 |