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A pre-LGM sandur deposit at Fiskarheden, NW Dalarna : sedimentology and glaciotectonic deformation

Flindt, Anne-Cécile LU (2016) In Dissertations in Geology at Lund University GEOR02 20151
Department of Geology
Abstract
The Fiskarheden quarry, situated in NW Dalarna, central Sweden, reveal thick deposits of coarse-grained sediments of Scott type facies association; a sandur deposited in an ice-proximal proglacial environment. Preliminary OSL dating of the sandur sediments suggest that they are of a pre-Saalian age (>200 000 years). Of special interest here is, besides its pre-LGM age, the large-scale and intense glaciotectonic deformation of the sediments. Both ductile folding and brittle deformation structures suggest glacial stress from NW which coincides with the trend of surrounding streamlined terrain and to that trend perpendicular Rogen moraine. From sedimentological relations and the glaciotectonic architecture it is suggested that either (i) the... (More)
The Fiskarheden quarry, situated in NW Dalarna, central Sweden, reveal thick deposits of coarse-grained sediments of Scott type facies association; a sandur deposited in an ice-proximal proglacial environment. Preliminary OSL dating of the sandur sediments suggest that they are of a pre-Saalian age (>200 000 years). Of special interest here is, besides its pre-LGM age, the large-scale and intense glaciotectonic deformation of the sediments. Both ductile folding and brittle deformation structures suggest glacial stress from NW which coincides with the trend of surrounding streamlined terrain and to that trend perpendicular Rogen moraine. From sedimentological relations and the glaciotectonic architecture it is suggested that either (i) the deformation of the sandur sediments took place when the glacier approached and overrode its own proglacial meltwater sediment, or that (ii) the deformation is from a younger ice advance over the area, decoupled from the deposition of the sandur sediments. The Fiskarheden sandur deposits are covered by traction till deposited from NE/NNE. This direction conforms to younger cross-cutting streamlined terrain to the older NW-SE system and is suggested to represent the LGM deglaciation phase over the area. (Less)
Popular Abstract (Swedish)
Ett grustag vid Fiskarheden, som ligger i nordvästra Dalarna, uppvisar tjocka avlagringar av grovkorniga sediment; en sanduravlagring av så kallad Scott-typ som deponerats i en is-proximal proglacial miljö. Preliminära OSL-dateringar av sandursedimenten tyder på att de är av en pre-Saalian ålder (>200 000 år). Av särskilt intresse här är, förutom dess höga ålder pre-daterande det senaste istidsmaximat, storskalig och intensiv glacialtektonisk deformation av sedimenten. Både plastiska och spröda deformationsstrukturer tyder glacialt tryck från nordväst, vilket sammanfaller med riktningen av omgivande strömlinjeformad terräng och från den trenden vinkelräta Rogenmoräner. Från sedimentologiska relationer och glacialtektonisk arkitektur... (More)
Ett grustag vid Fiskarheden, som ligger i nordvästra Dalarna, uppvisar tjocka avlagringar av grovkorniga sediment; en sanduravlagring av så kallad Scott-typ som deponerats i en is-proximal proglacial miljö. Preliminära OSL-dateringar av sandursedimenten tyder på att de är av en pre-Saalian ålder (>200 000 år). Av särskilt intresse här är, förutom dess höga ålder pre-daterande det senaste istidsmaximat, storskalig och intensiv glacialtektonisk deformation av sedimenten. Både plastiska och spröda deformationsstrukturer tyder glacialt tryck från nordväst, vilket sammanfaller med riktningen av omgivande strömlinjeformad terräng och från den trenden vinkelräta Rogenmoräner. Från sedimentologiska relationer och glacialtektonisk arkitektur föreslås att deformation av sanduravlagringen inträffade (i) antingen när glaciären närmade sig och överskred sina egen proglacial smältvattensediment, eller att (ii) deformationen är från ett yngre isöverskidande över området, frikopplat från deponerings av sandursediment. Fiskarhedens sandursediment är täckta av morän avsatt från NO till NNO. Denna riktning överensstämmer med yngre strömlinjeformat terräng som skär över det yngre NV mot SO-systemet av strömlinjeformer. Denna morän föreslås representera avsmältningsfasen av inlandsisen från den senaste glaciationen över området. (Less)
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author
Flindt, Anne-Cécile LU
supervisor
organization
course
GEOR02 20151
year
type
H2 - Master's Degree (Two Years)
subject
keywords
deformation, structures, sandur, glaciotectonic, glaciofluvial, fault-propagation fold
publication/series
Dissertations in Geology at Lund University
report number
463
language
English
id
8872795
date added to LUP
2016-05-17 12:43:00
date last changed
2016-05-17 12:43:00
@misc{8872795,
  abstract     = {The Fiskarheden quarry, situated in NW Dalarna, central Sweden, reveal thick deposits of coarse-grained sediments of Scott type facies association; a sandur deposited in an ice-proximal proglacial environment. Preliminary OSL dating of the sandur sediments suggest that they are of a pre-Saalian age (>200 000 years). Of special interest here is, besides its pre-LGM age, the large-scale and intense glaciotectonic deformation of the sediments. Both ductile folding and brittle deformation structures suggest glacial stress from NW which coincides with the trend of surrounding streamlined terrain and to that trend perpendicular Rogen moraine. From sedimentological relations and the glaciotectonic architecture it is suggested that either (i) the deformation of the sandur sediments took place when the glacier approached and overrode its own proglacial meltwater sediment, or that (ii) the deformation is from a younger ice advance over the area, decoupled from the deposition of the sandur sediments. The Fiskarheden sandur deposits are covered by traction till deposited from NE/NNE. This direction conforms to younger cross-cutting streamlined terrain to the older NW-SE system and is suggested to represent the LGM deglaciation phase over the area.},
  author       = {Flindt, Anne-Cécile},
  keyword      = {deformation,structures,sandur,glaciotectonic,glaciofluvial,fault-propagation fold},
  language     = {eng},
  note         = {Student Paper},
  series       = {Dissertations in Geology at Lund University},
  title        = {A pre-LGM sandur deposit at Fiskarheden, NW Dalarna : sedimentology and glaciotectonic deformation},
  year         = {2016},
}