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Geomagnetic field inclinations for the past 400 kyr from the 1-km core of the Hawaii Scientific Drilling Project

Holt, John W. and Kirschvink, Joseph L. and Garnier, Florence (1996) Geomagnetic field inclinations for the past 400 kyr from the 1-km core of the Hawaii Scientific Drilling Project. Journal of Geophysical Research B, 101 (B5). pp. 11655-11663. ISSN 0148-0227. https://resolver.caltech.edu/CaltechAUTHORS:20131126-103639559

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Abstract

A volcanic record of geomagnetic field inclination for the past ∼400 kyr at Hilo, Hawaii, has been obtained from the 941.5 m of core recovered by the Hawaii Scientific Drilling Project. The analysis of 195 lava flows reveals six instances of near-zero inclination and two instances of fully negative inclination (reverse polarity) within an otherwise normal-polarity core. In particular, flow unit 23 (∼178 m depth) records a horizontal inclination and may be associated with the Laschamp event; flow units 40 and 42 (∼260 m depth) record negative inclinations and are close in age to the Blake event; and flow unit 55 (∼320 m depth) records a negative inclination with a relative declination change of ∼75° with respect to the overlying flow and is probably the Jamaica/Biwa I/Pringle Falls event. The five instances of shallow inclination found below 400 m depth appear to have resulted from long-term secular variation as they are part of inclination swings between ∼0° and ∼60° with a periodicity of ∼10–50 kyr. In contrast, the inclination shifts at ∼178 m and ∼320 m depths significantly deviate from long-term trends, suggesting the existence of at least two independent processes producing time variations of the geomagnetic field. The secular variation has a mean of 30.9° (α_(95) = 2.27°), which is significantly shallower than the expected dipole mean of 36°. The dispersion (σ = 12.5°) agrees with global paleosecular variation data for 0–5 Ma and secular variation models.


Item Type:Article
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http://dx.doi.org/10.1029/95JB03843DOIArticle
http://onlinelibrary.wiley.com/doi/10.1029/95JB03843/abstractPublisherArticle
Additional Information:© 1996 American Geophysical Union. Received May 19, 1995; revised December 7, 1995; accepted December 19, 1995. We would like to thank Jonathan Hagstrum and Edward Mankinen for their thoughtful reviews; Duane Champion, Xavier Quidelleur, Liz Warner Holt, and Toshitsugu Yamazaki for helpful discussions; and Warren Sharp for providing radiometric ages soon after obtaining them. We are grateful to Catherine Kissel for spearheading the monumental task of drilling 1132 paleomagnetic samples from the 1-km core. Portions of this work were supported by NSF grants EAR-9117588 and EAR-9419041. This is California Institute of Technology contribution 5619. This is CFR contribution 1771.
Funders:
Funding AgencyGrant Number
NSFEAR-9117588
NSFEAR-9419041
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Caltech Division of Geological and Planetary Sciences5619
CFR 1771
Issue or Number:B5
Record Number:CaltechAUTHORS:20131126-103639559
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20131126-103639559
Official Citation:Holt, J. W., J. L. Kirschvink, and F. Garnier (1996), Geomagnetic field inclinations for the past 400 kyr from the 1-km core of the Hawaii Scientific Drilling Project, J. Geophys. Res., 101(B5), 11655–11663, doi:10.1029/95JB03843.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:42737
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:02 Dec 2013 16:41
Last Modified:03 Oct 2019 06:01

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