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Self-reversal and apparent magnetic excursions in Arctic sediments

Self-reversal and apparent magnetic excursions in Arctic sediments
Self-reversal and apparent magnetic excursions in Arctic sediments
The Arctic oceans have been fertile ground for the recording of apparent excursions of the geomagnetic field, implying that the high latitude field had unusual characteristics at least over the last 1–2 Myrs. Alternating field demagnetization of the natural remanent magnetization (NRM) of Core HLY0503-6JPC from the Mendeleev Ridge (Arctic Ocean) implies the presence of primary magnetizations with negative inclination apparently recording excursions in sediments deposited during the Brunhes Chron. Thermal demagnetization, on the other hand, indicates the presence of multiple (often anti-parallel) magnetization components with negative inclination components having blocking temperatures predominantly, but not entirely, below ~ 350 °C. Thermo-magnetic tests, X-ray diffraction (XRD) and scanning electron microscopy (SEM) indicate that the negative inclination components are carried by titanomaghemite, presumably formed by seafloor oxidation of titanomagnetite. The titanomaghemite apparently carries a chemical remanent magnetization (CRM) that is partially self-reversed relative to the detrital remanent magnetization (DRM) carried by the host titanomagnetite. The partial self-reversal could have been accomplished by ionic ordering during oxidation, thereby changing the balance of the magnetic moments in the ferrimagnetic sublattices.
arctic sediments, geomagnetic excursions, titanomaghemite, self-reversal
0012-821X
124-131
Channell, J.E.T.
f37676da-640c-4bdc-8f9f-e2ffa43fe449
Xuan, C.
3f3cad12-b17b-46ae-957a-b362def5b837
Channell, J.E.T.
f37676da-640c-4bdc-8f9f-e2ffa43fe449
Xuan, C.
3f3cad12-b17b-46ae-957a-b362def5b837

Channell, J.E.T. and Xuan, C. (2009) Self-reversal and apparent magnetic excursions in Arctic sediments. Earth and Planetary Science Letters, 284 (1-2), 124-131. (doi:10.1016/j.epsl.2009.04.020).

Record type: Article

Abstract

The Arctic oceans have been fertile ground for the recording of apparent excursions of the geomagnetic field, implying that the high latitude field had unusual characteristics at least over the last 1–2 Myrs. Alternating field demagnetization of the natural remanent magnetization (NRM) of Core HLY0503-6JPC from the Mendeleev Ridge (Arctic Ocean) implies the presence of primary magnetizations with negative inclination apparently recording excursions in sediments deposited during the Brunhes Chron. Thermal demagnetization, on the other hand, indicates the presence of multiple (often anti-parallel) magnetization components with negative inclination components having blocking temperatures predominantly, but not entirely, below ~ 350 °C. Thermo-magnetic tests, X-ray diffraction (XRD) and scanning electron microscopy (SEM) indicate that the negative inclination components are carried by titanomaghemite, presumably formed by seafloor oxidation of titanomagnetite. The titanomaghemite apparently carries a chemical remanent magnetization (CRM) that is partially self-reversed relative to the detrital remanent magnetization (DRM) carried by the host titanomagnetite. The partial self-reversal could have been accomplished by ionic ordering during oxidation, thereby changing the balance of the magnetic moments in the ferrimagnetic sublattices.

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More information

Published date: 30 June 2009
Keywords: arctic sediments, geomagnetic excursions, titanomaghemite, self-reversal
Organisations: Ocean and Earth Science

Identifiers

Local EPrints ID: 351193
URI: https://eprints.soton.ac.uk/id/eprint/351193
ISSN: 0012-821X
PURE UUID: 65d3f15b-9bed-42b2-b960-51fb86738678
ORCID for C. Xuan: ORCID iD orcid.org/0000-0003-4043-3073

Catalogue record

Date deposited: 16 Apr 2013 09:59
Last modified: 06 Jun 2018 12:24

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