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A sedimentary model for transverse inland dunes in central Scandinavia

Author:
  • Helena Alexanderson
  • Martin Bernhardson
  • Mona Henriksen
  • Edyta Kalinska-Nartisa
Publishing year: 2018
Language: English
Pages:
Document type: Poster

Abstract english

The largest dune fields in Sweden and Norway are small in international comparison but still form distinct parts of this previously glaciated landscape. The dunes formed c.10.5-9 ka ago, shortly after the last deglaciation, when winds close to the ice sheet were strong and vegetation was largely absent [1-4]. Since then they have been more or less stable and today they are covered by forest. Most of the dunes are curvi-linear in shape and formed transverse to the wind [5].

Here we present a sedimentary model for these transverse inland dunes, based on geophysical and sedimentological investigations of dunes at Skattungheden, Bonäsheden and Starmoen in central Sweden and south-eastern Norway. Ground-penetrating radar profiles reveal the main architectural elements of the dunes, while logging of sediment exposures in the dunes provide information on sedimentary structures. Grain-size analysis and scanning electron microscope studies of individual grains give us more detail on sediment characteristics.

The main dune body, consisting of cross beds generally dipping 25-30°, makes up the largest part of the dunes; minor elements include windward side cover, dune-crest superimposed features and dune-toe apron (Fig. 1). The dominating sediment structures are planar parallel lamination, massive to vaguely stratified beds and a few types of secondary structures, such as bioturbation or physical disturbances. Few large erosional discordances are seen, and the dominating depositional processes are wind-ripple migration and some grain fall on the sloping lee sides. The sediments are well-sorted fine-to-medium sand, dominated by quartz, but with significant amounts of feldspar as well as some lithic fragments, micas and heavy minerals. Most grains are angular to subrounded and their surfaces display few traces of aeolian transport. Overall, the dune sands show large similarities to their source material (glacifluvial deposits), which suggests only short transport and brief reworking by aeolian processes.

References

[1] Alexanderson, H. and M. Bernhardson, OSL dating and luminescence characteristics of aeolian deposits and their source material in Dalarna, central Sweden Boreas, 2016. 45: p. 876-893.
[2] Alexanderson, H. and M. Henriksen, A short-lived aeolian event during the Early Holocene in southeastern Norway. Quaternary Geochronology, 2015. 30: p. 175-180.
[3] Bernhardson, M. and H. Alexanderson, Early Holocene NW-W winds reconstructed from small dune fields, central Sweden. Boreas, 2018.
[4] Alexanderson, H. and D. Fabel, Holocene chronology of the Brattforsheden delta and inland dune field, SW Sweden. Geochronometria, 2015. 42: p. 1-16.
[5] Bernhardson, M. and H. Alexanderson, Early Holocene dune field development in Dalarna, central Sweden: A geomorphological and geophysical case study. Earth Surface Processes and Landforms, 2017. 42: p. 1847-1859.

Keywords

  • Geology

Other

10th International conference on aeolian research
2018-06-25 - 2018-06-29
Bordeaux, France
Published
  • Aeolian activity in Sweden: an unexplored environmental archive
Helena Alexandersson
E-mail: helena [dot] alexanderson [at] geol [dot] lu [dot] se

Professor

Quaternary Sciences

+46 46 222 44 83

435

16

Aeolian sand project

Project members
Members of the aeolian sand project: Martin Bernhardson, Sara Florén, Edyta Kalińska-Nartiša and Helena Alexanderson.

Read more about the project here.