Volcanic records of the Laschamp geomagnetic excursion from Mt Ruapehu, New Zealand

dc.contributor.authorIngham, Elizabeth
dc.contributor.authorTurner, G.M.
dc.contributor.authorConway, Chris E.
dc.contributor.authorHeslop, David
dc.contributor.authorRoberts, Andrew
dc.contributor.authorLeonard, Graham S.
dc.contributor.authorTownsend, Dougal B.
dc.contributor.authorCalvert, Andrew
dc.date.accessioned2020-12-20T20:58:29Z
dc.date.available2020-12-20T20:58:29Z
dc.date.issued2017
dc.date.updated2020-11-23T11:26:58Z
dc.description.abstractWe present palaeodirectional records of the Laschamp geomagnetic excursion from lavas on Mt Ruapehu, New Zealand. Fourteen lava flows on the northwestern and southern flanks of Mt Ruapehu, with 40Ar/39Ar weighted mean plateau ages that range from 46.3±2.0 to 39.9±1.4 ka, were studied. The youngest and older flows carry a normal polarity magnetization; however, six flows, dated between 46.3±2.0 and 42.7±1.8 ka, record excursional directions. Three of these flows record southerly palaeomagnetic declinations and negative inclinations that agree well with a published Laschamp record from the Auckland Volcanic Field (AVF). Together, the AVF and Mt Ruapehu lavas currently represent the only volcanic records of the Laschamp excursion outside the Chaîne des Puys region, France. Thus, they make an important contribution to the global set of Laschamp excursion records. Virtual geomagnetic pole (VGP) groups for the New Zealand and French records early in the excursion are compatible with a dipole-dominated field that rotated to an equatorial orientation while simultaneously decaying in strength. In contrast, younger excursional flows from France and New Zealand yield separate VGP groups, which suggest either that the field had a nondipolar morphology in this later phase, or that the VGP groups were not synchronous. 40Ar/39Ar ages for the Mt Ruapehu record are on average slightly older than published northern hemisphere ages and from the relative palaeointensity minimum in the GLOPIS sedimentary stack. Although few individual ages differ significantly at the 2σ level, the spread suggests an overall excursion duration that is longer than the currently accepted 1500 years. This age spread may result from excess Ar in magmas at the time of the eruption biasing the results to slightly older ages, or from non-synchronous excursional field behaviour at near-antipodal locations, or, possibly, a precursory phase prior to the main excursion
dc.format.mimetypeapplication/pdfen_AU
dc.identifier.issn0012-821X
dc.identifier.urihttp://hdl.handle.net/1885/218605
dc.language.isoen_AUen_AU
dc.publisherElsevier
dc.sourceEarth and Planetary Science Letters
dc.titleVolcanic records of the Laschamp geomagnetic excursion from Mt Ruapehu, New Zealand
dc.typeJournal article
local.bibliographicCitation.lastpage141
local.bibliographicCitation.startpage131
local.contributor.affiliationIngham, Elizabeth, College of Science, ANU
local.contributor.affiliationTurner, G.M., Victoria University of Wellington
local.contributor.affiliationConway, Chris E., Victoria University of Wellington
local.contributor.affiliationHeslop, David, College of Science, ANU
local.contributor.affiliationRoberts, Andrew, College of Science, ANU
local.contributor.affiliationLeonard, Graham S., Joint Centre for Disaster Research
local.contributor.affiliationTownsend, Dougal B., GNS Science
local.contributor.affiliationCalvert, Andrew, US Geological Survey
local.contributor.authoremailu4919989@anu.edu.au
local.contributor.authoruidIngham, Elizabeth, u4973893
local.contributor.authoruidHeslop, David, u4919989
local.contributor.authoruidRoberts, Andrew, u4817957
local.description.notesImported from ARIES
local.identifier.absfor040406 - Magnetism and Palaeomagnetism
local.identifier.ariespublicationa383154xPUB6558
local.identifier.citationvolume472
local.identifier.doi10.1016/j.epsl.2017.05.023
local.identifier.scopusID2-s2.0-85020399448
local.identifier.thomsonID000405153600012
local.identifier.uidSubmittedBya383154
local.type.statusPublished Version

Downloads