Further K-Ar dating and paleomagnetic study of the Auckland geomagnetic excursions

Mochizuki, Nobutatsu; Tsunakawa, Hideo; Shibuya, Hitoshi; Tagami, Takahiro; Ozawa, Ayako; Smith, I. E.

doi:10.1186/bf03352738

Cited by 21 publications

(18 citation statements)

References 42 publications

(48 reference statements)

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“…The number of records that exhibit the Mono Lake excursion is smaller than for the Laschamp excursion records: when combined with the wide range of ages for the Mono Lake excursion, this contributes to a smooth signal over the time period. However, we do note that the Mono Lake is recorded in lavas from New Zealand (Cassata et al, 2008;Cassidy & Hill, 2009;Mochizuki et al, 2004Mochizuki et al, , 2007 with ages in the range from 30 to 35 ka. Other excursions reported over the 0-100 ka period are Hilina Pali (17 ka) (Coe et al, 1978;Singer et al, 2014), Norwegian-Greenland Sea excursion (60 ka) (Laj & Channell, 2015;Nowaczyk et al, 1994), and Sk alamaelifell or post-Blake excursion (100 ka) (Jicha et al, 2011;Singer, 2014).…”

Section: 1029/2017gc007271mentioning

confidence: 62%

Global and Regional Assessments of Paleosecular Variation Activity Over the Past 100 ka

Panovska

Constable

Brown

2018

Geochem Geophys Geosyst

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We present a global compilation of paleomagnetic data spanning the past 100 ka. Sediment data comprise 61,687 declinations, 70,936 inclinations, and 69,596 relative paleointensities. Many sites are located in the northern Atlantic and western Pacific, with approximately twice as many data from the Northern Hemisphere as from the Southern Hemisphere. The 14,954 volcanic and archeomagnetic data are sparse, especially in the Southern Hemisphere. Directional and intensity information are aggregated under the paleosecular variation (PSV) index to assess occurrence of excursions over the past 100 ka. The Laschamp excursion (∼41 ka) is clearly defined across globally distributed sediment records with an average duration of 1,300 years. Regional stacks obtained using bootstrap resampling show a more pronounced Laschamp excursion in the Northern Hemisphere than in the Southern, and in the Atlantic Hemisphere compared with the Pacific. No anomalous indices occurred around the Mono Lake excursion or other periods in the bootstrap curves. This may result from low sedimentation rates, discrepancies in age scales, large age errors, and/or the lack of global character of any transitional events. These data and associated new uncertainty estimates for the sediment records provide a good foundation for global, time‐dependent, spherical harmonic field modeling for the past 100 ka.

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Section: 1029/2017gc007271mentioning

confidence: 62%

Global and Regional Assessments of Paleosecular Variation Activity Over the Past 100 ka

Panovska

Constable

Brown

2018

Geochem Geophys Geosyst

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“…Given the difficulty with excess Ar highlighted in the McDougall et al (1969) study that produced these results, we do not think this represents a reliable age for this centre. Mochizuki et al (2007). We consider these most recent analyses the most reliable for this centre, and the ArÁAr age is more precise ( (Table 4).…”

Section: Otuatauamentioning

confidence: 96%

“…Cassata et al (2008) carried out ArÁAr experiments on this centre; their weighted mean isochron age of multiple analyses (26.698 ka) provided an age younger than the KÁAr age (5595 ka) of Mochizuki et al (2007); however, the analyses were problematic and did not yield a reliable weighted mean plateau age. Based on discussions by Cassata et al (2008), neither the ArÁAr nor KÁAr ages determined so far should be relied upon.…”

Section: Hampton Parkmentioning

confidence: 99%

Age of the Auckland Volcanic Field: a review of existing data

Lindsay

Leonard

Smid

et al. 2011

New Zealand Journal of Geology and Geophysics

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Determining magnitudeÁfrequency relationships, a critical first step in assessing volcanic hazard, has been hampered in the Auckland Volcanic Field (AVF) by the difficulty in dating past eruptions from the field's c. 50 centres. We assessed 186 age determinations from 27 centres for reliability and consistency. Results indicate that only three centres (Rangitoto 0.6 ka; Mt Wellington 10 ka; Three Kings 28.5 ka) are reliably and accurately dated. Eight are reasonably reliably dated within a small age range: Crater Hill, Kohuora, Mt Richmond, Puketutu, Taylors Hill and Wiri Mountain (all 32Á34 ka); Ash Hill (32 ka); and Purchas Hill (11 ka). Tephrochronology of lake sediments and relative ages from stratigraphic relationships provide age constraints for a further 9 and 11 centres, respectively. Although recent ArÁAr studies show promise, ages of AVF centres generally remain poorly understood; this has implications for any statistical treatment of the distribution of volcanism in the AVF.

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“…The Mono Lake RPI low is recorded at ∼34.7 ka according to the correlation of the sedimentary paleoclimatic proxies with oxygen isotopes records from Greenland (GICC05 age model) [ NGRIP Dating Group 2006, and references therein]. Volcanic records of the Mono Lake excursion were also retrieved from New Zealand [ Shibuya et al , 1992; Mochizuki et al , 2004, 2006, 2007; Cassata et al , 2008; Cassidy and Hill , 2009], Hawaii [ Laj et al , 2002; Teanby et al , 2002] and the Canary Islands [ Kissel et al , 2011]. The case of the Mono Lake excursion, therefore, remains controversial.…”

Section: Introductionmentioning

confidence: 99%

Amplitude and timing of the Laschamp geomagnetic dipole low from the global atmospheric ¹⁰Be overproduction: Contribution of authigenic ¹⁰Be/⁹Be ratios in west equatorial Pacific sediments

Ménabréaz¹,

Bourlès²,

Thouveny³

2012

J. Geophys. Res.

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Authigenic 10Be/9Be ratios were measured along a sediment core collected in the west equatorial Pacific in order to reconstruct cosmogenic 10Be production variations near the equator, where the geomagnetic modulation is maximum. From 60 to 20 ka, the single significant 10Be production impulse recorded at 41 ka results from the geomagnetic dipole low that triggered the Laschamp excursion. No significant 10Be overproduction signature is recorded at the age of the Mono Lake excursion (∼34 ka). A compilation of authigenic 10Be/9Be records obtained from sediments was averaged over a 1 kyr window and compared with the 1 kyr averaged 10Be flux record of Greenland ice cores. Their remarkable similarity demonstrates that 10Be production is globally modulated by geomagnetic dipole variations and redistributed by atmosphere dynamics. After calibration using absolute values of the virtual dipole moment drawn from paleomagnetic database, the authigenic 10Be/9Be stack allows reconstructing the geomagnetic dipole moment variations over the 20–50 ka time interval. Between 48 and 41 ka, the dipole moment collapsed at a rate of −1.5 × 1022 A m2 kyr−1, which will be an interesting criterion for the assessment of the loss rate of the historical field and the comparison of dipole moment loss prior to excursions and reversals. After a 2 kyr duration of the minimum dipole moment (∼1 × 1022 A m2), a slow increase started at 39 ka, progressively reaching 5 × 1022 A m2 at 20 ka. The absence of a significant dipole moment drop at 34 ka, the age of the Mono lake excursion, suggests that the duration and amplitude of the dipole weakening cannot be compared with that of the Laschamp. This study provides a reliable basis to model the production of radiocarbon and in situ cosmogenic nuclides and to improve the calibration of these dating methods.

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Further K-Ar dating and paleomagnetic study of the Auckland geomagnetic excursions

Cited by 21 publications

References 42 publications

Global and Regional Assessments of Paleosecular Variation Activity Over the Past 100 ka

Global and Regional Assessments of Paleosecular Variation Activity Over the Past 100 ka

Age of the Auckland Volcanic Field: a review of existing data

Amplitude and timing of the Laschamp geomagnetic dipole low from the global atmospheric ¹⁰Be overproduction: Contribution of authigenic ¹⁰Be/⁹Be ratios in west equatorial Pacific sediments

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Further K-Ar dating and paleomagnetic study of the Auckland geomagnetic excursions

Cited by 21 publications

References 42 publications

Global and Regional Assessments of Paleosecular Variation Activity Over the Past 100 ka

Global and Regional Assessments of Paleosecular Variation Activity Over the Past 100 ka

Age of the Auckland Volcanic Field: a review of existing data

Amplitude and timing of the Laschamp geomagnetic dipole low from the global atmospheric 10Be overproduction: Contribution of authigenic 10Be/9Be ratios in west equatorial Pacific sediments

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Amplitude and timing of the Laschamp geomagnetic dipole low from the global atmospheric ¹⁰Be overproduction: Contribution of authigenic ¹⁰Be/⁹Be ratios in west equatorial Pacific sediments