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A new Holocene record of geomagnetic secular variation from Windermere, UK

A new Holocene record of geomagnetic secular variation from Windermere, UK
A new Holocene record of geomagnetic secular variation from Windermere, UK
Paleomagnetic secular variation (PSV) records serve as valuable independent stratigraphic correlation and dating tools for marine and terrestrial sediment sequences, and enhance knowledge of geomagnetic field dynamics. We present a new radiocarbon-dated record (WINPSV-12K) of Holocene geomagnetic secular variation from Windermere, updating the existing 1981 UK master PSV curve. Our analyses used continuous U-channel samples taken from the center of four sediment cores retrieved from Windermere in 2012. The natural remanent magnetization (NRM) of each U-channel was measured before and after stepwise alternating field (AF) demagnetization on a superconducting rock magnetometer at intervals of 0.5-cm or 1-cm. The NRM data reveal a stable and well-defined primary magnetization.

Component declinations and inclinations estimated using Principal Component Analysis (PCA) of NRM data from the four Windermere cores correlate well on their independent radiocarbon age models. The four records were stacked using a sliding window bootstrap method, resulting in a composite Holocene PSV record (WINPSV-12K).
On millennial timescales WINPSV-12K correlates well with other records from Western Europe and the northern North Atlantic to a resolution of ~1 kyr, given age uncertainties and spatial variability between records. WINPSV-12K also compares well to the CALS10k.2 and pfm9k.1a model predictions for Windermere. Key regionally-significant PSV inclination features of WINPSV-12K which correlate with other North Atlantic records include peaks at 5 – 6, 8.5, and 10 cal ka BP, and a trough at 7 cal ka BP. Key PSV declination features include the eastward swing from 5.5 – 2.3 cal ka BP followed by a major westward excursion at 2.3 cal ka BP, peaks at 1.1 and 7cal ka BP, and troughs at 5.4 and 8.2 cal ka BP, with the caveat that an estimated magnetic lock-in delay of at least 100 – 200 years is present. PSV variations on 1 – 3 kyr timescales are interpreted to represent strengthening and weakening of the North American versus the Siberian and European-Mediterranean high-latitude flux lobes, based on the close similarities between the North Atlantic regional records and the antiphase existing in the East Asian Stack record and the North East Pacific inclination stack. WINPSV-12K provides a regionally-important new PSV reference curve whose prominent features may serve as stratigraphic markers for North Atlantic paleo-records.
Paleomagnetism, lake sediments, Holocene, Windermere, Palaeosecular variation, Flux Lobes
0012-821X
108-122
Avery, Rachael S.
e2310327-14c0-4c0b-a03f-31207cab95c2
Xuan, Chuang
3f3cad12-b17b-46ae-957a-b362def5b837
Kemp, Alan E.S.
131b479e-c2c4-47ae-abe1-ad968490960e
Bull, Jonathan M.
974037fd-544b-458f-98cc-ce8eca89e3c8
Cotterill, Carol
cc09513b-fd65-4fa3-a95e-90fafb1aa37c
Fielding, John, James
0350985d-d245-4d72-bacd-03e48a05499d
Pearce, Richard
7d772b25-3ad0-4909-9a96-3a1a8111bc2f
Croudace, Ian
24deb068-d096-485e-8a23-a32b7a68afaf
Avery, Rachael S.
e2310327-14c0-4c0b-a03f-31207cab95c2
Xuan, Chuang
3f3cad12-b17b-46ae-957a-b362def5b837
Kemp, Alan E.S.
131b479e-c2c4-47ae-abe1-ad968490960e
Bull, Jonathan M.
974037fd-544b-458f-98cc-ce8eca89e3c8
Cotterill, Carol
cc09513b-fd65-4fa3-a95e-90fafb1aa37c
Fielding, John, James
0350985d-d245-4d72-bacd-03e48a05499d
Pearce, Richard
7d772b25-3ad0-4909-9a96-3a1a8111bc2f
Croudace, Ian
24deb068-d096-485e-8a23-a32b7a68afaf

Avery, Rachael S., Xuan, Chuang, Kemp, Alan E.S., Bull, Jonathan M., Cotterill, Carol, Fielding, John, James, Pearce, Richard and Croudace, Ian (2017) A new Holocene record of geomagnetic secular variation from Windermere, UK. Earth and Planetary Science Letters, 477, 108-122. (doi:10.1016/j.epsl.2017.08.025).

Record type: Article

Abstract

Paleomagnetic secular variation (PSV) records serve as valuable independent stratigraphic correlation and dating tools for marine and terrestrial sediment sequences, and enhance knowledge of geomagnetic field dynamics. We present a new radiocarbon-dated record (WINPSV-12K) of Holocene geomagnetic secular variation from Windermere, updating the existing 1981 UK master PSV curve. Our analyses used continuous U-channel samples taken from the center of four sediment cores retrieved from Windermere in 2012. The natural remanent magnetization (NRM) of each U-channel was measured before and after stepwise alternating field (AF) demagnetization on a superconducting rock magnetometer at intervals of 0.5-cm or 1-cm. The NRM data reveal a stable and well-defined primary magnetization.

Component declinations and inclinations estimated using Principal Component Analysis (PCA) of NRM data from the four Windermere cores correlate well on their independent radiocarbon age models. The four records were stacked using a sliding window bootstrap method, resulting in a composite Holocene PSV record (WINPSV-12K).
On millennial timescales WINPSV-12K correlates well with other records from Western Europe and the northern North Atlantic to a resolution of ~1 kyr, given age uncertainties and spatial variability between records. WINPSV-12K also compares well to the CALS10k.2 and pfm9k.1a model predictions for Windermere. Key regionally-significant PSV inclination features of WINPSV-12K which correlate with other North Atlantic records include peaks at 5 – 6, 8.5, and 10 cal ka BP, and a trough at 7 cal ka BP. Key PSV declination features include the eastward swing from 5.5 – 2.3 cal ka BP followed by a major westward excursion at 2.3 cal ka BP, peaks at 1.1 and 7cal ka BP, and troughs at 5.4 and 8.2 cal ka BP, with the caveat that an estimated magnetic lock-in delay of at least 100 – 200 years is present. PSV variations on 1 – 3 kyr timescales are interpreted to represent strengthening and weakening of the North American versus the Siberian and European-Mediterranean high-latitude flux lobes, based on the close similarities between the North Atlantic regional records and the antiphase existing in the East Asian Stack record and the North East Pacific inclination stack. WINPSV-12K provides a regionally-important new PSV reference curve whose prominent features may serve as stratigraphic markers for North Atlantic paleo-records.

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Accepted/In Press date: 17 August 2017
e-pub ahead of print date: 4 September 2017
Published date: 1 November 2017
Keywords: Paleomagnetism, lake sediments, Holocene, Windermere, Palaeosecular variation, Flux Lobes

Identifiers

Local EPrints ID: 413335
URI: https://eprints.soton.ac.uk/id/eprint/413335
ISSN: 0012-821X
PURE UUID: 4e2bf282-0385-47c7-9ba6-d84173690c20
ORCID for Rachael S. Avery: ORCID iD orcid.org/0000-0002-4439-4174
ORCID for Chuang Xuan: ORCID iD orcid.org/0000-0003-4043-3073

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Date deposited: 22 Aug 2017 16:31
Last modified: 15 Aug 2019 04:40

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Contributors

Author: Rachael S. Avery ORCID iD
Author: Chuang Xuan ORCID iD
Author: Alan E.S. Kemp
Author: Carol Cotterill
Author: Richard Pearce
Author: Ian Croudace

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