TY - JOUR
T1 - Time-transgressive tunnel valley formation indicated by infill sediment structure, North Sea - the role of glaciohydraulic supercooling
AU - Kristensen, Thomas Bojer
AU - Piotrowski, Jan
AU - Huuse, Mads
AU - Clausen, O.R.
AU - Hamberg, Lars
PY - 2008
Y1 - 2008
N2 - Structure and lithology of the infill sediments from 16 subglacial buried tunnel valleys of Pleistocene age in the North Sea were analyzed using 3D seismic data and geophysical log data from five hydrocarbon exploration wells. The infill sediments are characterized by three seismic facies: Facies I, the volumetrically most important and structurally most distinct, is composed of clinoform reflections downlapping axially up-valley (up-ice), Facies II is composed of near-horizontal, continuous and well layered reflections onlapping the clinoform reflections and the valley walls and Facies III is composed of clinoform reflections downlapping axially down-valley (down-ice). A model of formation of this sediment architecture is proposed, in which valley incision and infill are causally linked. It is proposed that Facies I is related to glaciohydraulic supercooling of subglacial meltwater in the distal parts of tunnel valleys. The valleys formed time-transgressively during ice retreat, whereby sediment eroded further up-ice was re-deposited along adverse subglacial slopes of the valleys close to the ice margin. The formation of Facies II and III is related to the deposition in proglacial basins during final deglaciation.
AB - Structure and lithology of the infill sediments from 16 subglacial buried tunnel valleys of Pleistocene age in the North Sea were analyzed using 3D seismic data and geophysical log data from five hydrocarbon exploration wells. The infill sediments are characterized by three seismic facies: Facies I, the volumetrically most important and structurally most distinct, is composed of clinoform reflections downlapping axially up-valley (up-ice), Facies II is composed of near-horizontal, continuous and well layered reflections onlapping the clinoform reflections and the valley walls and Facies III is composed of clinoform reflections downlapping axially down-valley (down-ice). A model of formation of this sediment architecture is proposed, in which valley incision and infill are causally linked. It is proposed that Facies I is related to glaciohydraulic supercooling of subglacial meltwater in the distal parts of tunnel valleys. The valleys formed time-transgressively during ice retreat, whereby sediment eroded further up-ice was re-deposited along adverse subglacial slopes of the valleys close to the ice margin. The formation of Facies II and III is related to the deposition in proglacial basins during final deglaciation.
M3 - Journal article
SN - 0197-9337
VL - 33
SP - 546
EP - 559
JO - Earth Surface Processes and Landforms
JF - Earth Surface Processes and Landforms
IS - 4
ER -