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Litostratigrafiska studier av en platåformad sand- och grusavlagring i Skuremåla, Blekinge

Stenfeldt, Fredrik (2006) In Dissertations in Geology at Lund University
Department of Geology
Abstract (Swedish)
I Skuremåla, Blekinge har litostratigrafiska studier utförts av en platåformad grus- och sandavlagring.
Skuremåla-avlagringen har tidigare beskrivits som ett delta med en överyta på 55 m ö h. Syftet med arbetet
är att tolka vad för sorts ”delta” Skuremåla-avlagringen utgör samt depositionsmiljön för sedimenten i fråga. I denna
studie har området undersökts genom jordartskartering samt genom skruvborrningar längs en profil över Skuremåla-
avlagringen, vilka tillsammans med en tidigare undersökning bildar underlag för upprättandet av en stratigrafi
över området. Stratigrafin har jämförts och tolkats utifrån en modell över förhållanden mellan olika litostratigrafiska
enheter i Blekinge. De två borrprofilerna som skruvborrningarna gav... (More)
I Skuremåla, Blekinge har litostratigrafiska studier utförts av en platåformad grus- och sandavlagring.
Skuremåla-avlagringen har tidigare beskrivits som ett delta med en överyta på 55 m ö h. Syftet med arbetet
är att tolka vad för sorts ”delta” Skuremåla-avlagringen utgör samt depositionsmiljön för sedimenten i fråga. I denna
studie har området undersökts genom jordartskartering samt genom skruvborrningar längs en profil över Skuremåla-
avlagringen, vilka tillsammans med en tidigare undersökning bildar underlag för upprättandet av en stratigrafi
över området. Stratigrafin har jämförts och tolkats utifrån en modell över förhållanden mellan olika litostratigrafiska
enheter i Blekinge. De två borrprofilerna som skruvborrningarna gav upphov till är placerade i områdets östra
respektive västra del. Resultaten visar på en lagerföljd som kan indelas i sex stratigrafiska lagerenheter enligt följande:
(1) undre grus och sand, (2) proximalvarviga sediment, (3) distalvarviga sediment, (4) silt, (5) övre grus och
sand samt (6) organiska sediment. Utifrån stratigrafiska förhållanden samt lagerenheternas mäktighet, utbredning
och sammansättning har Skuremåla-avlagringen tolkats som ett så kallat randfält. Randfältet byggdes upp nära
högsta kustlinjen i samband med deglaciationen i Blekinge med en isrand som kalvade i Baltiska Issjön. Inlandsisen
dränerades subglacialt genom smältvattentunnlar vilka transporterade smältvatten och sediment ut till tunnelmynningen
och därmed ut till Baltiska Issjön. I samband med att smältvatten och sediment lämnade smältvattentunneln
avtog energinivån dramatiskt och material deponerades lobformat utanför tunnelmynning. Efter inlandsisens reträtt
norrut följde sedimentation av årsvarviga sediment, först proximalvarviga sediment med mäktiga sommarbäddar
mellan vinterns lerskikt, och därefter som distalvarviga sediment med successivt allt tunnare sommarskikt. Högsta
kustlinjen utformades vid en regional nivå på 65 m ö h. Då landhöjningen var snabbare än havsytehöjningen följde
en negativ strandförskjutningen och områdets höjdpartier kom successivt att stiga upp ovanför vatten ytan. I samband
med strandlinjens passerande av Skuremåla-avlagringen avsattes svallsediment som den sista stratigrafiska
enheten i Baltiska Issjön. (Less)
Abstract
A lithostragraphic study has been performed of a plateau-shaped sand and gravel deposit at Skuremåla in
Blekinge, SE Sweden. The Skuremåla deposit has earlier been described as a delta with an upper surface 55 m a.s.l.
The purpose of this study is to re-evaluate this interpretation, i.e. is the Skuremåla deposits a delta or possibly another
type of formation. Furthermore, the investigation aims at a more comprehensive palaeoenvironment reconstruction.
This study has been performed as mapping of the area and there after auger drilling and sediment logging
along a profile across the Skuremåla deposit. Together with earlier investigations this constitutes the basis for establishing
a stratigraphy over the Skuremåla deposit. Based on two... (More)
A lithostragraphic study has been performed of a plateau-shaped sand and gravel deposit at Skuremåla in
Blekinge, SE Sweden. The Skuremåla deposit has earlier been described as a delta with an upper surface 55 m a.s.l.
The purpose of this study is to re-evaluate this interpretation, i.e. is the Skuremåla deposits a delta or possibly another
type of formation. Furthermore, the investigation aims at a more comprehensive palaeoenvironment reconstruction.
This study has been performed as mapping of the area and there after auger drilling and sediment logging
along a profile across the Skuremåla deposit. Together with earlier investigations this constitutes the basis for establishing
a stratigraphy over the Skuremåla deposit. Based on two profiles one located in the eastern side and the
other in the western side of the area, it can be concluded that the deposits can be divided into six stratigraphic units
as follows: (1) lower gravels and sands, (2) proximal varved sediments, (3) distal varved sediments, (4) silt, (5)
upper gravel and sands and, (6) organic sediments. On the basis of the sediment composition and stratigraphic relations
in vertical and lateral directions, the Skuremåla deposit has been interpreted as a subaqueous fan. The
subaqueous fan was built up during the deglaciation of Blekinge at a position close to the highest shoreline. The ice
sheet had then a calving ice-margin the Baltic Ice Lake, but here at a quite shallow depths. The ice was predominantly
drained in subglacial meltwater tunnels, transporting meltwater and sediments into the Baltic Ice Lake.
When meltwater and sediment left the tunnel the energy level decreased dramatically and the coarser sediment load
was deposited lob-shaped outside the ice tunnel mouth, whereas more fine-grained sediments were transported both
in overflows and in density current underflow further away from the meltwater tunnel. When the ice sheet retreated
further north, sedimentation commenced as first proximally-deposited varved sediment with thick sommer beds,
and later as distally-deposited varved sediments with gradually thinner summer beds. The highest shoreline was
regionally developed at ca 65 m a.s.l i.e the highest position reached by the Baltic Ice Lake. At deglaciation the
isostatic rise was faster than the eustatic rise. This resulted in a negative shoreline displacement and higher parts of
the area were gradually raised above the sea level and beach sediment where deposited as the Baltic Ice Lake component
of the Skuremåla deposit. (Less)
Please use this url to cite or link to this publication:
author
Stenfeldt, Fredrik
supervisor
organization
alternative title
Lithostratigraphic studies of a plateau-shaped sand and gravel deposit in Skuremåla, Blekinge
year
type
H1 - Master's Degree (One Year)
subject
keywords
Skuremåla, litostratigrafi, deglaciation, randfält, strandförskjutning, Baltiska Issjön, Blekinge, lithostratigraphy, subaqueous fan, shoreline displacement, Baltic Ice Lake
publication/series
Dissertations in Geology at Lund University
report number
207
language
English
id
2338101
date added to LUP
2012-02-02 15:39:45
date last changed
2012-02-02 15:39:45
@misc{2338101,
  abstract     = {A lithostragraphic study has been performed of a plateau-shaped sand and gravel deposit at Skuremåla in
Blekinge, SE Sweden. The Skuremåla deposit has earlier been described as a delta with an upper surface 55 m a.s.l.
The purpose of this study is to re-evaluate this interpretation, i.e. is the Skuremåla deposits a delta or possibly another
type of formation. Furthermore, the investigation aims at a more comprehensive palaeoenvironment reconstruction.
This study has been performed as mapping of the area and there after auger drilling and sediment logging
along a profile across the Skuremåla deposit. Together with earlier investigations this constitutes the basis for establishing
a stratigraphy over the Skuremåla deposit. Based on two profiles one located in the eastern side and the
other in the western side of the area, it can be concluded that the deposits can be divided into six stratigraphic units
as follows: (1) lower gravels and sands, (2) proximal varved sediments, (3) distal varved sediments, (4) silt, (5)
upper gravel and sands and, (6) organic sediments. On the basis of the sediment composition and stratigraphic relations
in vertical and lateral directions, the Skuremåla deposit has been interpreted as a subaqueous fan. The
subaqueous fan was built up during the deglaciation of Blekinge at a position close to the highest shoreline. The ice
sheet had then a calving ice-margin the Baltic Ice Lake, but here at a quite shallow depths. The ice was predominantly
drained in subglacial meltwater tunnels, transporting meltwater and sediments into the Baltic Ice Lake.
When meltwater and sediment left the tunnel the energy level decreased dramatically and the coarser sediment load
was deposited lob-shaped outside the ice tunnel mouth, whereas more fine-grained sediments were transported both
in overflows and in density current underflow further away from the meltwater tunnel. When the ice sheet retreated
further north, sedimentation commenced as first proximally-deposited varved sediment with thick sommer beds,
and later as distally-deposited varved sediments with gradually thinner summer beds. The highest shoreline was
regionally developed at ca 65 m a.s.l i.e the highest position reached by the Baltic Ice Lake. At deglaciation the
isostatic rise was faster than the eustatic rise. This resulted in a negative shoreline displacement and higher parts of
the area were gradually raised above the sea level and beach sediment where deposited as the Baltic Ice Lake component
of the Skuremåla deposit.},
  author       = {Stenfeldt, Fredrik},
  keyword      = {Skuremåla,litostratigrafi,deglaciation,randfält,strandförskjutning,Baltiska Issjön,Blekinge,lithostratigraphy,subaqueous fan,shoreline displacement,Baltic Ice Lake},
  language     = {eng},
  note         = {Student Paper},
  series       = {Dissertations in Geology at Lund University},
  title        = {Litostratigrafiska studier av en platåformad sand- och grusavlagring i Skuremåla, Blekinge},
  year         = {2006},
}