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Cryptotephra sedimentation processes within two lacustrine sequences from west central Sweden

Davies, SM; Elmquist, M; Bergman, J; Wohlfarth, B and Hammarlund, Dan LU (2007) In The Holocene 17(3). p.319-330
Abstract
Distal tephra horizons, particularly within lacustrine sequences, are increasingly being used as time-synchronous marker horizons within palaeoclimatic and palaeoenvironmental investigations. As sedimentary features marking the presence of these so-called cryptotephras are absent to the naked eye, it is of some importance that the stratigraphic position representing primary airfall, and likewise the timing Of the volcanic event, is accurately and consistently recorded amongst these deposits. Often tephra shards from a cryptotephra deposit can be found spanning several centimetres of sediments within lacustrine and peat sequences. Very few studies, however, have looked in detail at the sedimentation and vertical distribution of cryptotephra... (More)
Distal tephra horizons, particularly within lacustrine sequences, are increasingly being used as time-synchronous marker horizons within palaeoclimatic and palaeoenvironmental investigations. As sedimentary features marking the presence of these so-called cryptotephras are absent to the naked eye, it is of some importance that the stratigraphic position representing primary airfall, and likewise the timing Of the volcanic event, is accurately and consistently recorded amongst these deposits. Often tephra shards from a cryptotephra deposit can be found spanning several centimetres of sediments within lacustrine and peat sequences. Very few studies, however, have looked in detail at the sedimentation and vertical distribution of cryptotephra deposits within such sequences and, more importantly, the criteria for defining the correct stratigraphic position of the volcanic event. Two sediment cores from Lake Spaime and Lake Getvaltjarnen, west central Sweden are employed to investigate in detail the vertical distribution of the tephra shards derived from the AD 1875 eruption of the Askja volcano in Iceland. Detailed geochemical analysis of shards from both records indicate that products of the Askja eruption are present for at least 120 years and thus emphasize the importance of carefully identifying the correct horizon that marks the timing of the volcanic event rather than shards resulting from a period of reworking or downward migration. Both sites yield contrasting shard concentration profiles and thus raise a number of questions regarding the influence of site-specific processes on cryptotephra sedimentation, particularly the role of snow-beds acting as tephra traps, the possibility of reworking, and downward migration of shards in soft sediment. A second tephra is also identified at Lake Getvaltjarnen and is believed to originate from the AD 1477 Veidivotn eruption and represents the first occurrence of this tephra outside of Iceland. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Askja AD 1875 tephra, historical volcanic eruptions, cryptotephra sedimentation processes, lacustrine deposits, Iceland, Sweden
in
The Holocene
volume
17
issue
3
pages
319 - 330
publisher
SAGE Publications Inc.
external identifiers
  • wos:000247871700004
  • scopus:34347378511
ISSN
0959-6836
DOI
10.1177/0959683607076443
language
English
LU publication?
yes
id
841a47e5-c0f5-46bb-a3f0-3b006dee8171 (old id 618320)
date added to LUP
2007-12-13 12:40:56
date last changed
2017-05-14 03:39:42
@article{841a47e5-c0f5-46bb-a3f0-3b006dee8171,
  abstract     = {Distal tephra horizons, particularly within lacustrine sequences, are increasingly being used as time-synchronous marker horizons within palaeoclimatic and palaeoenvironmental investigations. As sedimentary features marking the presence of these so-called cryptotephras are absent to the naked eye, it is of some importance that the stratigraphic position representing primary airfall, and likewise the timing Of the volcanic event, is accurately and consistently recorded amongst these deposits. Often tephra shards from a cryptotephra deposit can be found spanning several centimetres of sediments within lacustrine and peat sequences. Very few studies, however, have looked in detail at the sedimentation and vertical distribution of cryptotephra deposits within such sequences and, more importantly, the criteria for defining the correct stratigraphic position of the volcanic event. Two sediment cores from Lake Spaime and Lake Getvaltjarnen, west central Sweden are employed to investigate in detail the vertical distribution of the tephra shards derived from the AD 1875 eruption of the Askja volcano in Iceland. Detailed geochemical analysis of shards from both records indicate that products of the Askja eruption are present for at least 120 years and thus emphasize the importance of carefully identifying the correct horizon that marks the timing of the volcanic event rather than shards resulting from a period of reworking or downward migration. Both sites yield contrasting shard concentration profiles and thus raise a number of questions regarding the influence of site-specific processes on cryptotephra sedimentation, particularly the role of snow-beds acting as tephra traps, the possibility of reworking, and downward migration of shards in soft sediment. A second tephra is also identified at Lake Getvaltjarnen and is believed to originate from the AD 1477 Veidivotn eruption and represents the first occurrence of this tephra outside of Iceland.},
  author       = {Davies, SM and Elmquist, M and Bergman, J and Wohlfarth, B and Hammarlund, Dan},
  issn         = {0959-6836},
  keyword      = {Askja AD 1875 tephra,historical volcanic eruptions,cryptotephra sedimentation processes,lacustrine deposits,Iceland,Sweden},
  language     = {eng},
  number       = {3},
  pages        = {319--330},
  publisher    = {SAGE Publications Inc.},
  series       = {The Holocene},
  title        = {Cryptotephra sedimentation processes within two lacustrine sequences from west central Sweden},
  url          = {http://dx.doi.org/10.1177/0959683607076443},
  volume       = {17},
  year         = {2007},
}