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Kvidingedeltat : bildningsprocesser och arkitektonisk uppbyggnadsmodell av ett glacifluvialt Gilbertdelta

Nilsson, Pernilla (2007) In Examensarbeten i geologi vid Lunds universitet
Department of Geology
Abstract (Swedish)
Kvidingefältet ligger i nordvästra Skåne på Söderåsens nordöstra sida och avlagringen är ett
delta som bildades i en havsvik under deglaciationen av området. Syftet med undersökningen är att göra en arkitektonisk
analys av Kvidingedeltats tredimensionella uppbyggnad och att ta reda på hur deltautbyggnaden gått till.
Sedimentologiska studier i form av översiktskartering utfördes i åtta av täkternas skärningar och sju detaljloggningar
genomfördes. Mätning med georadar i de oexploaterade områdena resulterade i sju radargram. Resultaten visar
att Kvidingedeltat är ett glacifluvialt Gilbert-delta och att havsviken vid avsättandet var 15-20 meter djup. Fyra
arkitektoniska grundelement identifieras i deltaavlagringen. De fyra elementen,... (More)
Kvidingefältet ligger i nordvästra Skåne på Söderåsens nordöstra sida och avlagringen är ett
delta som bildades i en havsvik under deglaciationen av området. Syftet med undersökningen är att göra en arkitektonisk
analys av Kvidingedeltats tredimensionella uppbyggnad och att ta reda på hur deltautbyggnaden gått till.
Sedimentologiska studier i form av översiktskartering utfördes i åtta av täkternas skärningar och sju detaljloggningar
genomfördes. Mätning med georadar i de oexploaterade områdena resulterade i sju radargram. Resultaten visar
att Kvidingedeltat är ett glacifluvialt Gilbert-delta och att havsviken vid avsättandet var 15-20 meter djup. Fyra
arkitektoniska grundelement identifieras i deltaavlagringen. De fyra elementen, kallade A, B, C och D, har även
underindelats. Element A– Deltaplanets sediment karaktäriseras av skivformade lager av grusiga litofacies och representerar
ett proximalt flätflodssystem som prograderat ut över deltat. Djupare kanaler har funnits i de yttersta
delarna av deltaplanet. Element B– Deltasluttningens element karaktäriseras av grusiga och sandiga klinoforma
lager som avsatts av massrörelser i deltasluttningen. Element C– Sedimenten vid deltasluttningens fot karaktäriseras
av sandig tråg- och plankorsskiktning och visar på dyner som avsatts vid deltafoten snett uppför sluttningen
eller i sluttningsriktningen. De visar också på uppgrundningsfaser under deltats bildning. Element D– Prodeltats
sediment karaktäriseras av en tabulär form med stor lateral utbredning och med horisontella lager av planlagrad
eller rippellaminerad finsand och silt som avsatts av ihållande turbiditströmmar i prodeltaområdet. Två olika avsättningsvarianter
har förekommit då deltat prograderat ut i bassängen. En första där strömmens utgångshastighet vid
sluttningskrönet varit hög vilket lett till avsättning av grövre material som sten och grus i deltasluttningen. Samtidigt
har en strömvirvel uppstått som genererat strömmar uppför deltasluttningen. En andra där utgångshastigheten
varit lägre vilket lett till avsättning av främst sand i deltasluttningen. Utbyggnaden av Kvidingedeltat har börjat som
ett iskontaktdelta i de sydostligaste delarna för att sedan övergå till ett glacifluvialt Gilbert-delta i det aktuella undersökningsområdet
som ligger i de norra och nordvästra delarna av deltat. Sedimenten i deltats yttersta delar har
troligen kommit från en smältande is som haft sin rand på Söderåsen och där smältvattnet dränerats genom den kanjon
som finns vid Klöva Hallar. Havsnivån vid tiden för bildandet av deltats yttersta delar låg på 45 meter över havet.
Utbyggnaden av Kvidingedeltat tog ca 150-200 år och avsattes något tidigare än 16 000 år före nutid. (Less)
Abstract
The Kvidinge deposit is situated in north-western Scania, southern Sweden. It is a delta formed in a bay
during the deglaciation of the area. The purpose of the investigation is to do an architectural analysis of the threedimensional
build-up of the Kvidinge deposit and to reconstruct the progradation of the delta. Sedimentary studies
have been performed in eight sections and seven logs have been recorded. GPR measurements was done in the unexploited
areas and resulted in seven GPR profiles. The results show that the Kvidinge deposit is a glaciofluvial
Gilbert-type delta deposited in a basin depth of 15-20 meters. Four main architectural elements was identified,
called A, B, C and D. Element A– The delta plane sediments are... (More)
The Kvidinge deposit is situated in north-western Scania, southern Sweden. It is a delta formed in a bay
during the deglaciation of the area. The purpose of the investigation is to do an architectural analysis of the threedimensional
build-up of the Kvidinge deposit and to reconstruct the progradation of the delta. Sedimentary studies
have been performed in eight sections and seven logs have been recorded. GPR measurements was done in the unexploited
areas and resulted in seven GPR profiles. The results show that the Kvidinge deposit is a glaciofluvial
Gilbert-type delta deposited in a basin depth of 15-20 meters. Four main architectural elements was identified,
called A, B, C and D. Element A– The delta plane sediments are characterised by gravels with tabular forms and is
representing a proximal braided river system that was prograding in the delta plane during the delta build out. In the
distal areas of the river system deeper channels were located. Element B– The delta slope sediments are represented
by clinoforms with gravelly and sandy sediments deposited by mass flows on the delta slope. Element C– The delta
toe sediments are represented by sandy trough- and planar cross bedding and show dunes deposited by turbidity
currents in the delta toe area, either towards or in the same direction as the delta slope. The sediments in C also indicate
shallowing-upward phases during the build-out of the delta. Element D– The prodelta sediments are characterised
by a large lateral extension of tabular forms with planar- and ripple laminated fine sand and silt, which was
deposited by continuing turbidity currents in the prodelta area. Two patterns of deposition have occurred during the
delta progradation. In the first type the channel water current had high velocities when reaching the basin which has
led to deposition of coarse material, gravel and cobbles, on the delta slope. High velocities gave rise to a lee-side
vortex which led to back-flow currents climbing the delta slope. In the second type the channel water current has
had lower velocities which led to deposition of mainly sand on the delta slope. The build-out of the Kvidinge deposit
started as an ice-contact delta in the south-eastern parts and proceeded into a glaciofluvial Gilbert-type delta in
the investigation area in the northern and north-western parts of the delta. The sediments in the investigated area
likely originate from a melting glacier on the Söderåsen horst with meltwater drainage through the canyon at Klöva
Hallar. The shoreline at the time of deposition of the investigated part of the delta is estimated to 45 meters above
the present sea level. The build-up of the entire delta took approximately 150-200 years and occurred around
16 000 years ago. (Less)
Please use this url to cite or link to this publication:
author
Nilsson, Pernilla
supervisor
organization
alternative title
The Kvidinge delta : sedimentary processes and depositional architecture of a glaciofluvial Gilbert-type delta
year
type
H1 - Master's Degree (One Year)
subject
keywords
Kvidingedeltat, Gilbertdelta, isälvsdelta, georadar, arkitektoniska element, sluttningsprocesser, the Kvidinge deposit, Gilbert-type delta, glaciofluvial delta, ground penetrating radar (GPR), architectural elements, delta-slope processes
publication/series
Examensarbeten i geologi vid Lunds universitet
report number
211
language
Swedish
id
2335576
date added to LUP
2012-01-31 17:02:10
date last changed
2012-01-31 17:02:10
@misc{2335576,
  abstract     = {{The Kvidinge deposit is situated in north-western Scania, southern Sweden. It is a delta formed in a bay
during the deglaciation of the area. The purpose of the investigation is to do an architectural analysis of the threedimensional
build-up of the Kvidinge deposit and to reconstruct the progradation of the delta. Sedimentary studies
have been performed in eight sections and seven logs have been recorded. GPR measurements was done in the unexploited
areas and resulted in seven GPR profiles. The results show that the Kvidinge deposit is a glaciofluvial
Gilbert-type delta deposited in a basin depth of 15-20 meters. Four main architectural elements was identified,
called A, B, C and D. Element A– The delta plane sediments are characterised by gravels with tabular forms and is
representing a proximal braided river system that was prograding in the delta plane during the delta build out. In the
distal areas of the river system deeper channels were located. Element B– The delta slope sediments are represented
by clinoforms with gravelly and sandy sediments deposited by mass flows on the delta slope. Element C– The delta
toe sediments are represented by sandy trough- and planar cross bedding and show dunes deposited by turbidity
currents in the delta toe area, either towards or in the same direction as the delta slope. The sediments in C also indicate
shallowing-upward phases during the build-out of the delta. Element D– The prodelta sediments are characterised
by a large lateral extension of tabular forms with planar- and ripple laminated fine sand and silt, which was
deposited by continuing turbidity currents in the prodelta area. Two patterns of deposition have occurred during the
delta progradation. In the first type the channel water current had high velocities when reaching the basin which has
led to deposition of coarse material, gravel and cobbles, on the delta slope. High velocities gave rise to a lee-side
vortex which led to back-flow currents climbing the delta slope. In the second type the channel water current has
had lower velocities which led to deposition of mainly sand on the delta slope. The build-out of the Kvidinge deposit
started as an ice-contact delta in the south-eastern parts and proceeded into a glaciofluvial Gilbert-type delta in
the investigation area in the northern and north-western parts of the delta. The sediments in the investigated area
likely originate from a melting glacier on the Söderåsen horst with meltwater drainage through the canyon at Klöva
Hallar. The shoreline at the time of deposition of the investigated part of the delta is estimated to 45 meters above
the present sea level. The build-up of the entire delta took approximately 150-200 years and occurred around
16 000 years ago.}},
  author       = {{Nilsson, Pernilla}},
  language     = {{swe}},
  note         = {{Student Paper}},
  series       = {{Examensarbeten i geologi vid Lunds universitet}},
  title        = {{Kvidingedeltat : bildningsprocesser och arkitektonisk uppbyggnadsmodell av ett glacifluvialt Gilbertdelta}},
  year         = {{2007}},
}