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Multi-proxy identification of the Laschamp geomagnetic field excursion in Lake Pupuke, New Zealand
Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
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2011 (English)In: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, Vol. 311, no 1-2, 155-164 p.Article in journal (Refereed) Published
Abstract [en]

We present palaeomagnetic and cosmogenic radionuclide records of the Laschamp geomagnetic excursion in Lake Pupuke, a maar lake in Auckland, New Zealand. Laschamp was identified by a combination of relative palaeointensity, (10)Be and (14)C data from the lake sediments and represents the first such record from the Southern Hemisphere. Despite the high organic carbon content, which causes relatively weak natural remanent magnetisations, the geomagnetic intensity minimum associated with the Laschamp excursion is identifiable as a relative palaeointensity minimum that is synchronous with (i) a peak in (10)Be concentration and (ii) an anomaly in Delta(14)C. The Lake Pupuke time scale, provided by (14)C data calibrated with INTCAL09, places the (10)Be maximum at the same time as a (10)Be maximum in Greenland ice cores when secured to the GICC05 time scale. The central age of the Laschamp geomagnetic excursion in Lake Pupuke as defined by the (10)Be prediction peak is c. 41 kyr, which confirms its global application as a palaeomagnetic isochron. Anomalous palaeomagnetic directional data at c. 32 kyr in the Lake Pupuke sediments may represent the Mono Lake geomagnetic excursion, but tephra layers caused by frequent eruptions in the Auckland volcanic field during this excursion probably disrupted the palaeointensity signal. The study highlights the value of combining traditional palaeomagnetic methods with measurements of cosmogenic radionuclides in the quest for accurate and precise geochronologies during MIS3, a time of rapid global climate change.

Place, publisher, year, edition, pages
2011. Vol. 311, no 1-2, 155-164 p.
Keyword [en]
Laschamp excursion, geomagnetic field intensity, cosmogenic radionuclides, palaeomagnetism, lake sediments, Lake Pupuke
National Category
Earth and Related Environmental Sciences
URN: urn:nbn:se:uu:diva-167664DOI: 10.1016/j.epsl.2011.08.050ISI: 000298270100014OAI: oai:DiVA.org:uu-167664DiVA: diva2:488119
Available from: 2012-02-01 Created: 2012-01-31 Last updated: 2012-02-01Bibliographically approved

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Aldahan, AlaPossnert, Göran
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