Webbläsaren som du använder stöds inte av denna webbplats. Alla versioner av Internet Explorer stöds inte längre, av oss eller Microsoft (läs mer här: * https://www.microsoft.com/en-us/microsoft-365/windows/end-of-ie-support).

Var god och använd en modern webbläsare för att ta del av denna webbplats, som t.ex. nyaste versioner av Edge, Chrome, Firefox eller Safari osv.

Dan Hammarlund

Dan Hammarlund

Professor

Dan Hammarlund

Cryptotephra sedimentation processes within two lacustrine sequences from west central Sweden

Författare

  • SM Davies
  • M Elmquist
  • J Bergman
  • B Wohlfarth
  • Dan Hammarlund

Summary, in English

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.

Avdelning/ar

  • Kvartärgeologi

Publiceringsår

2007

Språk

Engelska

Sidor

319-330

Publikation/Tidskrift/Serie

The Holocene

Volym

17

Issue

3

Dokumenttyp

Artikel i tidskrift

Förlag

SAGE Publications

Ämne

  • Geology

Nyckelord

  • Askja AD 1875 tephra
  • historical volcanic eruptions
  • cryptotephra sedimentation processes
  • lacustrine deposits
  • Iceland
  • Sweden

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 0959-6836