Identification and definition of primary and reworked tephra in Late Glacial and Holocene marine shelf sediments off North Iceland
Abstract Nine tephra layers in marine sediment cores (MD99‐2271 and MD99‐2275) from the North Icelandic shelf, spanning the Late Glacial and the Holocene, have been investigated to evaluate the effectiveness of methods to detect tephra layers in marine environments, to pinpoint the stratigraphic lev...
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crwiley:10.1002/jqs.1474 2024-09-30T14:37:36+00:00 Identification and definition of primary and reworked tephra in Late Glacial and Holocene marine shelf sediments off North Iceland Gudmundsdóttir, Esther Ruth Eiríksson, Jón Larsen, Gudrún 2011 http://dx.doi.org/10.1002/jqs.1474 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fjqs.1474 https://onlinelibrary.wiley.com/doi/pdf/10.1002/jqs.1474 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Journal of Quaternary Science volume 26, issue 6, page 589-602 ISSN 0267-8179 1099-1417 journal-article 2011 crwiley https://doi.org/10.1002/jqs.1474 2024-09-17T04:47:20Z Abstract Nine tephra layers in marine sediment cores (MD99‐2271 and MD99‐2275) from the North Icelandic shelf, spanning the Late Glacial and the Holocene, have been investigated to evaluate the effectiveness of methods to detect tephra layers in marine environments, to pinpoint the stratigraphic level of the time signal the tephra layers provide, and to discriminate between primary and reworked tephra layers in a marine environment. These nine tephra layers are the Borrobol‐like tephra, Vedde Ash, Askja S tephra, Saksunarvatn ash, and Hekla 5, Hekla 4, Hekla 3, Hekla 1104 and V1477 tephras. The methods used were visual inspection, magnetic susceptibility, X‐ray photography, mineralogical counts, grain size and morphological measurements, and microprobe analysis. The results demonstrate that grain size measurements and mineralogical counts are the most effective methods to detect tephra layers in this environment, revealing all nine tephra layers in question. Definition of the tephra layers revealed a 2–3 cm diffuse upper boundary in eight of the nine tephra layers and 2–3 cm diffuse lower boundary in two tephra layers. Using a multi‐parameter approach the stratigraphic position of a tephra layer was determined where the rate of change of the parameters tested was the greatest compared with background values below the tephra. The first attempt to use grain morphology to distinguish between primary and reworked tephra in a marine environment suggests that this method can be effective in verifying whether a tephra layer is primary or reworked. Morphological measurements and microprobe analyses in combination with other methods can be used to identify primary tephra layers securely. The study shows that there is a need to apply a combination of methods to detect, define (the time signal) and discriminate between primary and reworked tephra in marine environments. Copyright © 2011 John Wiley & Sons, Ltd. Article in Journal/Newspaper Iceland Wiley Online Library Askja ENVELOPE(-16.802,-16.802,65.042,65.042) Saksunarvatn ENVELOPE(-7.150,-7.150,62.233,62.233) Journal of Quaternary Science 26 6 589 602 |
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Open Polar |
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Wiley Online Library |
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crwiley |
language |
English |
description |
Abstract Nine tephra layers in marine sediment cores (MD99‐2271 and MD99‐2275) from the North Icelandic shelf, spanning the Late Glacial and the Holocene, have been investigated to evaluate the effectiveness of methods to detect tephra layers in marine environments, to pinpoint the stratigraphic level of the time signal the tephra layers provide, and to discriminate between primary and reworked tephra layers in a marine environment. These nine tephra layers are the Borrobol‐like tephra, Vedde Ash, Askja S tephra, Saksunarvatn ash, and Hekla 5, Hekla 4, Hekla 3, Hekla 1104 and V1477 tephras. The methods used were visual inspection, magnetic susceptibility, X‐ray photography, mineralogical counts, grain size and morphological measurements, and microprobe analysis. The results demonstrate that grain size measurements and mineralogical counts are the most effective methods to detect tephra layers in this environment, revealing all nine tephra layers in question. Definition of the tephra layers revealed a 2–3 cm diffuse upper boundary in eight of the nine tephra layers and 2–3 cm diffuse lower boundary in two tephra layers. Using a multi‐parameter approach the stratigraphic position of a tephra layer was determined where the rate of change of the parameters tested was the greatest compared with background values below the tephra. The first attempt to use grain morphology to distinguish between primary and reworked tephra in a marine environment suggests that this method can be effective in verifying whether a tephra layer is primary or reworked. Morphological measurements and microprobe analyses in combination with other methods can be used to identify primary tephra layers securely. The study shows that there is a need to apply a combination of methods to detect, define (the time signal) and discriminate between primary and reworked tephra in marine environments. Copyright © 2011 John Wiley & Sons, Ltd. |
format |
Article in Journal/Newspaper |
author |
Gudmundsdóttir, Esther Ruth Eiríksson, Jón Larsen, Gudrún |
spellingShingle |
Gudmundsdóttir, Esther Ruth Eiríksson, Jón Larsen, Gudrún Identification and definition of primary and reworked tephra in Late Glacial and Holocene marine shelf sediments off North Iceland |
author_facet |
Gudmundsdóttir, Esther Ruth Eiríksson, Jón Larsen, Gudrún |
author_sort |
Gudmundsdóttir, Esther Ruth |
title |
Identification and definition of primary and reworked tephra in Late Glacial and Holocene marine shelf sediments off North Iceland |
title_short |
Identification and definition of primary and reworked tephra in Late Glacial and Holocene marine shelf sediments off North Iceland |
title_full |
Identification and definition of primary and reworked tephra in Late Glacial and Holocene marine shelf sediments off North Iceland |
title_fullStr |
Identification and definition of primary and reworked tephra in Late Glacial and Holocene marine shelf sediments off North Iceland |
title_full_unstemmed |
Identification and definition of primary and reworked tephra in Late Glacial and Holocene marine shelf sediments off North Iceland |
title_sort |
identification and definition of primary and reworked tephra in late glacial and holocene marine shelf sediments off north iceland |
publisher |
Wiley |
publishDate |
2011 |
url |
http://dx.doi.org/10.1002/jqs.1474 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fjqs.1474 https://onlinelibrary.wiley.com/doi/pdf/10.1002/jqs.1474 |
long_lat |
ENVELOPE(-16.802,-16.802,65.042,65.042) ENVELOPE(-7.150,-7.150,62.233,62.233) |
geographic |
Askja Saksunarvatn |
geographic_facet |
Askja Saksunarvatn |
genre |
Iceland |
genre_facet |
Iceland |
op_source |
Journal of Quaternary Science volume 26, issue 6, page 589-602 ISSN 0267-8179 1099-1417 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1002/jqs.1474 |
container_title |
Journal of Quaternary Science |
container_volume |
26 |
container_issue |
6 |
container_start_page |
589 |
op_container_end_page |
602 |
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1811640403994083328 |