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Remanence acquisition efficiency in biogenic and detrital magnetite and recording of geomagnetic paleointensity

Remanence acquisition efficiency in biogenic and detrital magnetite and recording of geomagnetic paleointensity
Remanence acquisition efficiency in biogenic and detrital magnetite and recording of geomagnetic paleointensity
Relative paleointensity (RPI) variations of Earth's magnetic field are widely used to understand geomagnetic field behavior and to develop age models for sedimentary sequences. RPI estimation is based on a series of assumptions. One key assumption that is rarely considered is that all magnetic particles in the sediment acquired a magnetization in an identical manner. In this paper, we test this assumption for sediments from the eastern equatorial Pacific Ocean that record well-documented global RPI variations over the last ∼780 kyr. The magnetization is carried by two stable single domain magnetic components, which we identify as magnetite magnetofossils and titanomagnetite nanoparticle inclusions within larger silicate particles. By analyzing signals carried by the two components separately, we determine for the first time that magnetic nanoparticle inclusions can cause their host particles to record reliable but inefficient sedimentary paleomagnetic signals. The magnetization carried by biogenic magnetite is acquired more efficiently than that carried by the nanoparticle inclusions. Variations in the concentration of both components are modulated climatically so that they record nearly identical RPI signals. In many sediment types, there is no correlation between the concentrations of different magnetic components so that variable remanence acquisition efficiency will complicate RPI recording. Our work demonstrates that detailed assessment of paleomagnetic recording by each constituent magnetic component needs to become a routine part of sedimentary RPI analysis.
1525-2027
1435-1450
Chen, Liang
15459db0-4299-44b7-beaf-fb646add66ac
Heslop, David
f32aae36-7f51-40e1-bf7d-54a561369a8d
Roberts, Andrew P.
7365c819-82a3-4dea-b4fe-3a1b6c823562
Chang, Liao
7ab080ee-fa04-4e3a-86d3-07625c55c468
Zhao, Xiang
99ee573a-4607-40b5-a473-2046d623a2e0
Mcgregor, Helen V.
30d557cd-ea20-4e9d-9553-c5c4e34955f2
Marino, Gianluca
40d6f3f2-0905-4c0f-8eb9-6d577b2833bb
Rodriguez-sanz, Laura
4810aac4-1e34-498e-90c3-1881cd76df09
Rohling, Eelco J.
a2a27ef2-fcce-4c71-907b-e692b5ecc685
Pälike, Heiko
41eaa71b-043f-4e6d-87b3-ac5e6ea239c5
Chen, Liang
15459db0-4299-44b7-beaf-fb646add66ac
Heslop, David
f32aae36-7f51-40e1-bf7d-54a561369a8d
Roberts, Andrew P.
7365c819-82a3-4dea-b4fe-3a1b6c823562
Chang, Liao
7ab080ee-fa04-4e3a-86d3-07625c55c468
Zhao, Xiang
99ee573a-4607-40b5-a473-2046d623a2e0
Mcgregor, Helen V.
30d557cd-ea20-4e9d-9553-c5c4e34955f2
Marino, Gianluca
40d6f3f2-0905-4c0f-8eb9-6d577b2833bb
Rodriguez-sanz, Laura
4810aac4-1e34-498e-90c3-1881cd76df09
Rohling, Eelco J.
a2a27ef2-fcce-4c71-907b-e692b5ecc685
Pälike, Heiko
41eaa71b-043f-4e6d-87b3-ac5e6ea239c5

Chen, Liang, Heslop, David, Roberts, Andrew P., Chang, Liao, Zhao, Xiang, Mcgregor, Helen V., Marino, Gianluca, Rodriguez-sanz, Laura, Rohling, Eelco J. and Pälike, Heiko (2017) Remanence acquisition efficiency in biogenic and detrital magnetite and recording of geomagnetic paleointensity. Geochemistry, Geophysics, Geosystems, 18 (4), 1435-1450. (doi:10.1002/2016GC006753).

Record type: Article

Abstract

Relative paleointensity (RPI) variations of Earth's magnetic field are widely used to understand geomagnetic field behavior and to develop age models for sedimentary sequences. RPI estimation is based on a series of assumptions. One key assumption that is rarely considered is that all magnetic particles in the sediment acquired a magnetization in an identical manner. In this paper, we test this assumption for sediments from the eastern equatorial Pacific Ocean that record well-documented global RPI variations over the last ∼780 kyr. The magnetization is carried by two stable single domain magnetic components, which we identify as magnetite magnetofossils and titanomagnetite nanoparticle inclusions within larger silicate particles. By analyzing signals carried by the two components separately, we determine for the first time that magnetic nanoparticle inclusions can cause their host particles to record reliable but inefficient sedimentary paleomagnetic signals. The magnetization carried by biogenic magnetite is acquired more efficiently than that carried by the nanoparticle inclusions. Variations in the concentration of both components are modulated climatically so that they record nearly identical RPI signals. In many sediment types, there is no correlation between the concentrations of different magnetic components so that variable remanence acquisition efficiency will complicate RPI recording. Our work demonstrates that detailed assessment of paleomagnetic recording by each constituent magnetic component needs to become a routine part of sedimentary RPI analysis.

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Chen_et_al-2017-Geochemistry,_Geophysics,_Geosystems - Version of Record
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Accepted/In Press date: 17 March 2017
e-pub ahead of print date: 17 March 2017
Published date: April 2017

Identifiers

Local EPrints ID: 413158
URI: https://eprints.soton.ac.uk/id/eprint/413158
ISSN: 1525-2027
PURE UUID: 21af964e-c1e1-4dd9-a145-334e171101c0
ORCID for Eelco J. Rohling: ORCID iD orcid.org/0000-0001-5349-2158

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Date deposited: 16 Aug 2017 16:30
Last modified: 20 Jul 2019 04:58

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