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FENNOSTACK and FENNORPIS: Varve dated Holocene palaeomagnetic secular variation and relative palaeointensity stacks for Fennoscandia

Snowball, Ian LU ; Zillén, Lovisa LU ; Ojala, Antti; Saarinen, Timo and Sandgren, Per LU (2007) In Earth and Planetary Science Letters 255. p.106-116
Abstract
A Holocene palaeomagnetic secular variation master curve (FENNOSTACK) and a relative palaeointensity curve (FENNORPIS) for Fennoscandia are presented. These curves were produced by stacking palaeomagnetic data obtained from six annually laminated (varved) lake sediment sequences and one non-laminated sediment sequence. The six independent varve chronologies were combined to form a timescale, which extends between the present year and 10,200 Cal yr BP. Smoothed inclination and declination curves show trends that are similar to a palaeomagnetic secular variation curve for the United Kingdom, except that the ages of most of the statistically significant features are a few hundred years younger in the Fennoscandian data set. These differences... (More)
A Holocene palaeomagnetic secular variation master curve (FENNOSTACK) and a relative palaeointensity curve (FENNORPIS) for Fennoscandia are presented. These curves were produced by stacking palaeomagnetic data obtained from six annually laminated (varved) lake sediment sequences and one non-laminated sediment sequence. The six independent varve chronologies were combined to form a timescale, which extends between the present year and 10,200 Cal yr BP. Smoothed inclination and declination curves show trends that are similar to a palaeomagnetic secular variation curve for the United Kingdom, except that the ages of most of the statistically significant features are a few hundred years younger in the Fennoscandian data set. These differences are most likely due to excessively old ages of the United Kingdom features produced by the radiocarbon dating of bulk sediments. The standardized relative palaeointensity stack shows that the intensity of the geomagnetic field in Fennoscandia was highest at 2300 Cal yr BP and lowest at 7000 Cal yr BP. Three palaeointensity peaks (PIPs) and three palaeointensity lows (PILs) are identified in FENNORPIS and indicate that the intensity of geomagnetic field varied significantly on millennial scales in this region during the Holocene, but there is much scatter in the reconstruction prior to 8000 Cal yr BP. Higher frequency palaeointensity features present in individual records are not significant in the stacked data set, which implies that these are a result of local environmental bias. Significant discrepancies exist between the data and the output of the CALS7K.2 geomagnetic field model for the last 7000 yr. In particular, the largest declination swing observed in the data at 2670 Cal yr BP (feature “f”) is not produced by the model, which is most likely due to the influence of an inaccurately dated Icelandic secular variation curve on the model result. Short term trends in standardized relative palaeointensity do differ from the model output, but it is difficult to make a comparison because of the relative nature of the sediment record. Better absolute palaeointensity data are needed to reduce uncertainties in reconstructions of past geomagnetic field strength. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Finland, varves, Sweden, relative palaeointensity, secular variation, palaeomagnetism, Holocene
in
Earth and Planetary Science Letters
volume
255
pages
106 - 116
publisher
Elsevier
external identifiers
  • wos:000245143600010
  • scopus:33847037454
ISSN
1385-013X
DOI
10.1016/j.epsl.2006.12.009
language
English
LU publication?
yes
id
bdb3cada-5d91-4332-b6ae-9584f070e796 (old id 627231)
date added to LUP
2007-12-13 15:03:01
date last changed
2017-10-01 03:44:30
@article{bdb3cada-5d91-4332-b6ae-9584f070e796,
  abstract     = {A Holocene palaeomagnetic secular variation master curve (FENNOSTACK) and a relative palaeointensity curve (FENNORPIS) for Fennoscandia are presented. These curves were produced by stacking palaeomagnetic data obtained from six annually laminated (varved) lake sediment sequences and one non-laminated sediment sequence. The six independent varve chronologies were combined to form a timescale, which extends between the present year and 10,200 Cal yr BP. Smoothed inclination and declination curves show trends that are similar to a palaeomagnetic secular variation curve for the United Kingdom, except that the ages of most of the statistically significant features are a few hundred years younger in the Fennoscandian data set. These differences are most likely due to excessively old ages of the United Kingdom features produced by the radiocarbon dating of bulk sediments. The standardized relative palaeointensity stack shows that the intensity of the geomagnetic field in Fennoscandia was highest at 2300 Cal yr BP and lowest at 7000 Cal yr BP. Three palaeointensity peaks (PIPs) and three palaeointensity lows (PILs) are identified in FENNORPIS and indicate that the intensity of geomagnetic field varied significantly on millennial scales in this region during the Holocene, but there is much scatter in the reconstruction prior to 8000 Cal yr BP. Higher frequency palaeointensity features present in individual records are not significant in the stacked data set, which implies that these are a result of local environmental bias. Significant discrepancies exist between the data and the output of the CALS7K.2 geomagnetic field model for the last 7000 yr. In particular, the largest declination swing observed in the data at 2670 Cal yr BP (feature “f”) is not produced by the model, which is most likely due to the influence of an inaccurately dated Icelandic secular variation curve on the model result. Short term trends in standardized relative palaeointensity do differ from the model output, but it is difficult to make a comparison because of the relative nature of the sediment record. Better absolute palaeointensity data are needed to reduce uncertainties in reconstructions of past geomagnetic field strength.},
  author       = {Snowball, Ian and Zillén, Lovisa and Ojala, Antti and Saarinen, Timo and Sandgren, Per},
  issn         = {1385-013X},
  keyword      = {Finland,varves,Sweden,relative palaeointensity,secular variation,palaeomagnetism,Holocene},
  language     = {eng},
  pages        = {106--116},
  publisher    = {Elsevier},
  series       = {Earth and Planetary Science Letters},
  title        = {FENNOSTACK and FENNORPIS: Varve dated Holocene palaeomagnetic secular variation and relative palaeointensity stacks for Fennoscandia},
  url          = {http://dx.doi.org/10.1016/j.epsl.2006.12.009},
  volume       = {255},
  year         = {2007},
}