3D- seismic exploration data and shallow cores have been used to study glacial deposits along the... more 3D- seismic exploration data and shallow cores have been used to study glacial deposits along the shelf break/upper continental slope off mid Norway. Glacial fed fans are ubiquitous phenomena on the Norwegian continental slope. Such fans were deposited along the ice front when it reached the shelf break, and are usually found distal to cross-shelf troughs, where glacial debris flows reached hundreds of kilometres down the slope (e.g. c. 500 km on the North Sea Fan). The study area is located in an interfan area, where an up to 250 m thick glacial package (reaching c. 100 km down slope) has previously only been imaged as a seismically transparent wedge, even on high-resolution 2D data. However, the use of seismic attribute analysis on the 3D data volume has made it possible to resolve the internal geometry of the wedge. The attribute analysis reveals a complex internal structure, showing that the wedge consists of coalescing debris flow lobes. The wedge has an average gradient of 0.7...
During the Northern Hemisphere glaciations ice sheets shaped the Fennoscandian landscape into its... more During the Northern Hemisphere glaciations ice sheets shaped the Fennoscandian landscape into its present form. Along the southwestern Fennoscandian coastline the prominent sub-marine Norwegian Channel has been the main transport route for Pleistocene glacigenic erosional products from SE Norway and SW Sweden to the Norwegian Sea. The Norwegian Channel reaches a maximum water depth of 700 m in the Skagerrak and has been occupied by repeated ice streams the last 1.1 million years. Glacigenic erosional products were also fed into the Norwegian Channel through the western Norwegian fjord systems during glacial stages. The main depocentre for the eroded products was the North Sea Fan complex at the mouth of the channel, where the sediments transported at the base of the Norwegian Channel Ice Stream were deposited as stacks of glacigenic debris flows. The Pleistocene part of the fan complex, reaches a maximum thickness of c. 1500 m and comprises nearly 40 000 km3 of sediments. Close to 8...
A major problem for understanding the dynamics of ice streams has been a lack of precise data on ... more A major problem for understanding the dynamics of ice streams has been a lack of precise data on ice streaming longevity and sediment transport efficacy. Here we present the first well-constrained data on sediment flux from a paleoice stream. This has been achieved by computing the volume of sediment deposited as debris flows on the fan located at the outlet
ABSTRACT The marine-based Atlantic periphery of the last NW European Ice Sheet experienced signif... more ABSTRACT The marine-based Atlantic periphery of the last NW European Ice Sheet experienced significant advances and retreats of its marine sector during its existence. It therefore had considerable potential to intermittently inject freshwater or ice pulses to the North Atlantic. These European inputs had poorly known consequences for ocean circulation and climate. Here we examine the history of the western margin of the European Ice Sheet, from 34 to 15 cal ka BP, and use a combination of modelling and proxy evidence to explore the impact on the North Atlantic of the fresh water and iceberg injections that accompanied phases of retreat of the marine sector of the NW European Ice Sheet. We find that the lack of geographical synchronicity in the responses of the different components of the 3000 km long sector meant that the scale of the climate consequences of ice discharge most likely remained regional, except during the final deglaciation phase, around 17–15 cal ka BP. At this time, as the later component of the recently introduced concept of an extended Heinrich event H1, both proxy and modelling evidence suggest rapid sector collapse led to partial shut-down of the Atlantic overturning and a basin-wide cooling.
Data from eastern England, Scotland, the northern North Sea and western Norway have been compiled... more Data from eastern England, Scotland, the northern North Sea and western Norway have been compiled in order to outline our current knowledge of the Middle and Late Weichselian glacial history of this region. Radiometric dates and their geological context from key sites in the region are presented and discussed. Based on the available information the following conclusions can be made: (i) Prior to 39 cal ka and most likely after ca 50 cal ka Scotland and southern Norway were extensively glaciated. Most likely the central North Sea was not glaciated at this time and grounded ice did not reach the shelf edge. (ii) During the time interval between 29 and 39 ka periods with ameliorated climate (including the Ålesund, Sandnes and Tolsta Interstadials) alternated with periods of restricted glaciation in Scotland and western Norway. (iii) Between 29 and 25 ka maximum Weichselian glaciation of the region occurred, with the Fennoscandian and British ice sheets coalescing in the central North Sea. (iv) Decoupling of the ice sheets had occurred at 25 ka, with development of a marine embayment in the northern North Sea (v) Between 22 and 19 ka glacial ice expanded westwards from Scandinavia onto the North Sea Plateau in the Tampen readvance. (vi) The last major expansion of glacial ice in the offshore areas was between 17.5 and 15.5 ka. At this time ice expanded in the north-western part of the region onto the Måløy Plateau from Norway and across Caithness and Orkney and to east of Shetland from the Moray Firth. The Norwegian Channel Ice Stream (NCIS), which drained major parts of the south-western Fennoscandian Ice Sheet, was active at several occasions between 29 and 18 ka.
3D- seismic exploration data and shallow cores have been used to study glacial deposits along the... more 3D- seismic exploration data and shallow cores have been used to study glacial deposits along the shelf break/upper continental slope off mid Norway. Glacial fed fans are ubiquitous phenomena on the Norwegian continental slope. Such fans were deposited along the ice front when it reached the shelf break, and are usually found distal to cross-shelf troughs, where glacial debris flows reached hundreds of kilometres down the slope (e.g. c. 500 km on the North Sea Fan). The study area is located in an interfan area, where an up to 250 m thick glacial package (reaching c. 100 km down slope) has previously only been imaged as a seismically transparent wedge, even on high-resolution 2D data. However, the use of seismic attribute analysis on the 3D data volume has made it possible to resolve the internal geometry of the wedge. The attribute analysis reveals a complex internal structure, showing that the wedge consists of coalescing debris flow lobes. The wedge has an average gradient of 0.7...
During the Northern Hemisphere glaciations ice sheets shaped the Fennoscandian landscape into its... more During the Northern Hemisphere glaciations ice sheets shaped the Fennoscandian landscape into its present form. Along the southwestern Fennoscandian coastline the prominent sub-marine Norwegian Channel has been the main transport route for Pleistocene glacigenic erosional products from SE Norway and SW Sweden to the Norwegian Sea. The Norwegian Channel reaches a maximum water depth of 700 m in the Skagerrak and has been occupied by repeated ice streams the last 1.1 million years. Glacigenic erosional products were also fed into the Norwegian Channel through the western Norwegian fjord systems during glacial stages. The main depocentre for the eroded products was the North Sea Fan complex at the mouth of the channel, where the sediments transported at the base of the Norwegian Channel Ice Stream were deposited as stacks of glacigenic debris flows. The Pleistocene part of the fan complex, reaches a maximum thickness of c. 1500 m and comprises nearly 40 000 km3 of sediments. Close to 8...
A major problem for understanding the dynamics of ice streams has been a lack of precise data on ... more A major problem for understanding the dynamics of ice streams has been a lack of precise data on ice streaming longevity and sediment transport efficacy. Here we present the first well-constrained data on sediment flux from a paleoice stream. This has been achieved by computing the volume of sediment deposited as debris flows on the fan located at the outlet
ABSTRACT The marine-based Atlantic periphery of the last NW European Ice Sheet experienced signif... more ABSTRACT The marine-based Atlantic periphery of the last NW European Ice Sheet experienced significant advances and retreats of its marine sector during its existence. It therefore had considerable potential to intermittently inject freshwater or ice pulses to the North Atlantic. These European inputs had poorly known consequences for ocean circulation and climate. Here we examine the history of the western margin of the European Ice Sheet, from 34 to 15 cal ka BP, and use a combination of modelling and proxy evidence to explore the impact on the North Atlantic of the fresh water and iceberg injections that accompanied phases of retreat of the marine sector of the NW European Ice Sheet. We find that the lack of geographical synchronicity in the responses of the different components of the 3000 km long sector meant that the scale of the climate consequences of ice discharge most likely remained regional, except during the final deglaciation phase, around 17–15 cal ka BP. At this time, as the later component of the recently introduced concept of an extended Heinrich event H1, both proxy and modelling evidence suggest rapid sector collapse led to partial shut-down of the Atlantic overturning and a basin-wide cooling.
Data from eastern England, Scotland, the northern North Sea and western Norway have been compiled... more Data from eastern England, Scotland, the northern North Sea and western Norway have been compiled in order to outline our current knowledge of the Middle and Late Weichselian glacial history of this region. Radiometric dates and their geological context from key sites in the region are presented and discussed. Based on the available information the following conclusions can be made: (i) Prior to 39 cal ka and most likely after ca 50 cal ka Scotland and southern Norway were extensively glaciated. Most likely the central North Sea was not glaciated at this time and grounded ice did not reach the shelf edge. (ii) During the time interval between 29 and 39 ka periods with ameliorated climate (including the Ålesund, Sandnes and Tolsta Interstadials) alternated with periods of restricted glaciation in Scotland and western Norway. (iii) Between 29 and 25 ka maximum Weichselian glaciation of the region occurred, with the Fennoscandian and British ice sheets coalescing in the central North Sea. (iv) Decoupling of the ice sheets had occurred at 25 ka, with development of a marine embayment in the northern North Sea (v) Between 22 and 19 ka glacial ice expanded westwards from Scandinavia onto the North Sea Plateau in the Tampen readvance. (vi) The last major expansion of glacial ice in the offshore areas was between 17.5 and 15.5 ka. At this time ice expanded in the north-western part of the region onto the Måløy Plateau from Norway and across Caithness and Orkney and to east of Shetland from the Moray Firth. The Norwegian Channel Ice Stream (NCIS), which drained major parts of the south-western Fennoscandian Ice Sheet, was active at several occasions between 29 and 18 ka.
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