Glacial dynamics and till genesis in hilly terrain : A study in the Tallträsk area, central-northern Sweden
This study deals with the influence of topography on glacial dynamics and the genesis of till in an area of moder-ate bedrock relief. An area 25 km west of Lycksele, northern Sweden, was investigated using geomorphological and sedimentological methods. The bedrock is dominated by coarse-grained gran...
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Ekologi, miljö och geovetenskap
2007
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ftumeauniv:oai:DiVA.org:umu-1345 2023-10-09T21:52:26+02:00 Glacial dynamics and till genesis in hilly terrain : A study in the Tallträsk area, central-northern Sweden Ivarsson, Hans 2007 application/pdf http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1345 eng eng Ekologi, miljö och geovetenskap Umeå : Ekologi, miljö och geovetenskap http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1345 urn:isbn:91-7264-377-2 info:eu-repo/semantics/openAccess till analyses glacial stratigraphy subglacial deposition deglaciation hilly terrain northern Sweden Physical Geography Naturgeografi Doctoral thesis, monograph info:eu-repo/semantics/doctoralThesis text 2007 ftumeauniv 2023-09-22T13:48:02Z This study deals with the influence of topography on glacial dynamics and the genesis of till in an area of moder-ate bedrock relief. An area 25 km west of Lycksele, northern Sweden, was investigated using geomorphological and sedimentological methods. The bedrock is dominated by coarse-grained granites and the topography, ranging in altitude between 310 and 490 m. a.s.l., is characterized by relatively wide, free-lying hills. The erosional and depositional features provide evidence of several glacial events, with regional ice flows from approximately the same direction (NW-NNW). The gravel fraction of the till is dominated by material transported more than 10 km. However, the total glacial erosion has been modest, as indicated by the frequent occurrence of residual pre-glacial weathering features. There is no evidence of warm-based conditions during the period when the ice divide of the Late Weichselian ice sheet was situated E-SE of the study area. The major mor-phological impact is most likely by pre-Late Weichselian ice sheets. The general stratigraphy at the valley floors is a complex sequence of heterogeneous till and beds of sorted sediments with some evidence of glacial deformation covered by an up to 2.5-m-thick, texturally homogeneous till layer with distinct fissility structure and clast fabric orientation. The lower unit is interpreted as pre-Late Weichselian marginal deposits, and the upper till as mainly formed during rigid-bed conditions, i.e. by lodgement, during the last deglaciation. The role of pervasive deformation and melt-out in the formation of the upper till are discussed. Inferred mainly from till fabrics it is evident that the ice flow was strongly topographically controlled within a relatively wide marginal zone of the retreating ice. At the summits of the hills there are only signs of very weak glacial abrasive and depositional activity, sug-gesting frozen based conditions over the summits until a very late stage of the deglaciation. The very thin till at the summits, which also lay ... Doctoral or Postdoctoral Thesis Ice Sheet Northern Sweden Umeå University: Publications (DiVA) Moder ENVELOPE(-62.533,-62.533,-76.100,-76.100) Tallträsk ENVELOPE(18.848,18.848,65.582,65.582) |
institution |
Open Polar |
collection |
Umeå University: Publications (DiVA) |
op_collection_id |
ftumeauniv |
language |
English |
topic |
till analyses glacial stratigraphy subglacial deposition deglaciation hilly terrain northern Sweden Physical Geography Naturgeografi |
spellingShingle |
till analyses glacial stratigraphy subglacial deposition deglaciation hilly terrain northern Sweden Physical Geography Naturgeografi Ivarsson, Hans Glacial dynamics and till genesis in hilly terrain : A study in the Tallträsk area, central-northern Sweden |
topic_facet |
till analyses glacial stratigraphy subglacial deposition deglaciation hilly terrain northern Sweden Physical Geography Naturgeografi |
description |
This study deals with the influence of topography on glacial dynamics and the genesis of till in an area of moder-ate bedrock relief. An area 25 km west of Lycksele, northern Sweden, was investigated using geomorphological and sedimentological methods. The bedrock is dominated by coarse-grained granites and the topography, ranging in altitude between 310 and 490 m. a.s.l., is characterized by relatively wide, free-lying hills. The erosional and depositional features provide evidence of several glacial events, with regional ice flows from approximately the same direction (NW-NNW). The gravel fraction of the till is dominated by material transported more than 10 km. However, the total glacial erosion has been modest, as indicated by the frequent occurrence of residual pre-glacial weathering features. There is no evidence of warm-based conditions during the period when the ice divide of the Late Weichselian ice sheet was situated E-SE of the study area. The major mor-phological impact is most likely by pre-Late Weichselian ice sheets. The general stratigraphy at the valley floors is a complex sequence of heterogeneous till and beds of sorted sediments with some evidence of glacial deformation covered by an up to 2.5-m-thick, texturally homogeneous till layer with distinct fissility structure and clast fabric orientation. The lower unit is interpreted as pre-Late Weichselian marginal deposits, and the upper till as mainly formed during rigid-bed conditions, i.e. by lodgement, during the last deglaciation. The role of pervasive deformation and melt-out in the formation of the upper till are discussed. Inferred mainly from till fabrics it is evident that the ice flow was strongly topographically controlled within a relatively wide marginal zone of the retreating ice. At the summits of the hills there are only signs of very weak glacial abrasive and depositional activity, sug-gesting frozen based conditions over the summits until a very late stage of the deglaciation. The very thin till at the summits, which also lay ... |
format |
Doctoral or Postdoctoral Thesis |
author |
Ivarsson, Hans |
author_facet |
Ivarsson, Hans |
author_sort |
Ivarsson, Hans |
title |
Glacial dynamics and till genesis in hilly terrain : A study in the Tallträsk area, central-northern Sweden |
title_short |
Glacial dynamics and till genesis in hilly terrain : A study in the Tallträsk area, central-northern Sweden |
title_full |
Glacial dynamics and till genesis in hilly terrain : A study in the Tallträsk area, central-northern Sweden |
title_fullStr |
Glacial dynamics and till genesis in hilly terrain : A study in the Tallträsk area, central-northern Sweden |
title_full_unstemmed |
Glacial dynamics and till genesis in hilly terrain : A study in the Tallträsk area, central-northern Sweden |
title_sort |
glacial dynamics and till genesis in hilly terrain : a study in the tallträsk area, central-northern sweden |
publisher |
Ekologi, miljö och geovetenskap |
publishDate |
2007 |
url |
http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1345 |
long_lat |
ENVELOPE(-62.533,-62.533,-76.100,-76.100) ENVELOPE(18.848,18.848,65.582,65.582) |
geographic |
Moder Tallträsk |
geographic_facet |
Moder Tallträsk |
genre |
Ice Sheet Northern Sweden |
genre_facet |
Ice Sheet Northern Sweden |
op_relation |
http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1345 urn:isbn:91-7264-377-2 |
op_rights |
info:eu-repo/semantics/openAccess |
_version_ |
1779315602104516608 |