Postglacial mass movements and depositional environments in a high-latitude fjord system – Hardangerfjorden, Western Norway

Bellwald, Benjamin; Hjelstuen, Berit Oline; Sejrup, Hans Petter; Haflidason, Haflidi

doi:10.1016/j.margeo.2016.06.002

Cited by 35 publications

(21 citation statements)

References 52 publications

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“…However, other trigger mechanisms could be responsible for the disturbed sediments in Lake Buarvatnet, for example, seismic activity (Bellwald et al . ).…”

Section: Discussionmentioning

confidence: 97%

“…During a GLOF event, higher discharge containing cold and sediment-laden water could potentially have created such an underflow. However, other trigger mechanisms could be responsible for the disturbed sediments in Lake Buarvatnet, for example, seismic activity (Bellwald et al 2016). GLOFs in Buarvatnet (D).…”

Section: Interpretation Of the Sediments From Buarvatnetmentioning

confidence: 99%

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Glacier outburst floods reconstructed from lake sediments and their implications for Holocene variations of the plateau glacier Folgefonna in western Norway

Røthe

Bakke

Støren

2019

Boreas

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A sudden release of large volumes of water during a glacier outburst flood (GLOF) is a major hazard worldwide. Here, we identify the sedimentary signature of glacial and non‐glacial processes, including GLOFs, based on lacustrine sediments from the distal glacier‐fed Lake Buarvatnet in western Norway. Historically documented GLOFs in 2002 CE and during the 1980s CE are identified in the 210Pb‐ and 14C‐dated sediments. These events have the same sedimentary signature as 12 earlier events throughout the Holocene interpreted to represent previous GLOFs in the catchment. The GLOFs are interpreted to have occurred during periods when the glacier extent was similar to the modern positions, and the events are thus used to pinpoint past positions of the glacier terminus and, hence, the equilibrium line altitudes (ELAs). The results indicate that the glacier Svartenutbreen, located at the eastern part of Folgefonna, had a similar size in 2002 CE as c. 8200–8300 cal. a BP, corresponding to the 8.2 ka event in the North Atlantic region. The regrowth of Sørfonna after the Holocene Thermal Optimum occurred at c. 6900 cal. a BP and Svartenutbreen was at modern size and extent in the periods c. 6400, c. 5450, c. 4850, c. 3850, c. 3550 and c. 1650 cal. a BP. Since 1650 cal. a BP, we infer that the glacier was larger than the 2002 CE glacier extent until 1910 CE when a GLOF occurred. Svartenutbreen has been retreating since 1910 CE, which led to the ice damming of the two historical GLOFs in the 1980s and 2002 CE separated by a glacier advance in the 1990s CE. The findings are discussed and compared to other regional glacier reconstructions in Norway, and emphasize the value of identifying and utilizing GLOFs as an indicator of past ELA variability.

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“…However, other trigger mechanisms could be responsible for the disturbed sediments in Lake Buarvatnet, for example, seismic activity (Bellwald et al . ).…”

Section: Discussionmentioning

confidence: 97%

Section: Interpretation Of the Sediments From Buarvatnetmentioning

confidence: 99%

Glacier outburst floods reconstructed from lake sediments and their implications for Holocene variations of the plateau glacier Folgefonna in western Norway

Røthe

Bakke

Støren

2019

Boreas

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“…In high-latitude fjords and glacial troughs beyond the coastline, the unlithified sediment accumulation may be taken to represent material deposited since these areas were last occupied by grounded ice, during ice retreat following the LGM (e.g. Aarseth, 1997;Gilbert et al, 1998;Hjelstuen et al, 2009;Hogan et al, 2012;Bellwald et al, 2016;Callard et al, 2018;Neilsen and Rasmussen, 2018). This glacimarine sedimentation has two components (Fig.…”

Section: Glacial Volumes Fluxes and Erosion Ratesmentioning

confidence: 99%

“…10.6-9.4 ka (Young et al, 2013;Streuff et al, 2017). Similarly, fjords in Norway, east Greenland and Patagonia are known to contain 100-500 m of deglacial infill (Aarseth, 1997;Andrews et al, 1994;Bellwald et al, 2016;Fernandez et al, 2016), and seismic profiles of the inner shelf basin at the modern Pine Island Glacier ice shelf edge reveal that it holds > 300 m of presumed ice-proximal sediment (Gohl, 2010;Nitsche et al, 2013). Given the similarity in fluxes between the palaeo-Jakobshavn and Petermann ice streams, we suggest that the lack of thick basin fill at Petermann is due to a shorter pe-riod of stabilization there, increased trapping efficiency of the large basin in front of the Jakobshavn sill when compared to the seafloor morphology of Hall Basin, or some combination of both factors.…”

Section: Comparisons With Other Ice Stream Systems: Glacial Sediment mentioning

confidence: 99%

Glacial sedimentation, fluxes and erosion rates associated with ice retreat in Petermann Fjord and Nares Strait, north-west Greenland

et al. 2020

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Abstract. Petermann Fjord is a deep (>1000 m) fjord that incises the coastline of north-west Greenland and was carved by an expanded Petermann Glacier, one of the six largest outlet glaciers draining the modern Greenland Ice Sheet (GrIS). Between 5 and 70 m of unconsolidated glacigenic material infills in the fjord and adjacent Nares Strait, deposited as the Petermann and Nares Strait ice streams retreated through the area after the Last Glacial Maximum. We have investigated the deglacial deposits using seismic stratigraphic techniques and have correlated our results with high-resolution bathymetric data and core lithofacies. We identify six seismo-acoustic facies in more than 3500 line kilometres of sub-bottom and seismic-reflection profiles throughout the fjord, Hall Basin and Kennedy Channel. Seismo-acoustic facies relate to bedrock or till surfaces (Facies I), subglacial deposition (Facies II), deposition from meltwater plumes and icebergs in quiescent glacimarine conditions (Facies III, IV), deposition at grounded ice margins during stillstands in retreat (grounding-zone wedges; Facies V) and the redeposition of material downslope (Facies IV). These sediment units represent the total volume of glacial sediment delivered to the mapped marine environment during retreat. We calculate a glacial sediment flux for the former Petermann ice stream as 1080–1420 m3 a−1 per metre of ice stream width and an average deglacial erosion rate for the basin of 0.29–0.34 mm a−1. Our deglacial erosion rates are consistent with results from Antarctic Peninsula fjord systems but are several times lower than values for other modern GrIS catchments. This difference is attributed to fact that large volumes of surface water do not access the bed in the Petermann system, and we conclude that glacial erosion is limited to areas overridden by streaming ice in this large outlet glacier setting. Erosion rates are also presented for two phases of ice retreat and confirm that there is significant variation in rates over a glacial–deglacial transition. Our new glacial sediment fluxes and erosion rates show that the Petermann ice stream was approximately as efficient as the palaeo-Jakobshavn Isbræ at eroding, transporting and delivering sediment to its margin during early deglaciation.

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“…Most importantly, it has been pointed out that the loading applied by earthquakes during the deglaciation due to the isostatic rebound could lead to slope failures (Bellwald, Hjelstuen, Sejrup, & Haflidason, 2016;L'Heureux et al, 2013). Hampel, Hetzel, Maniatis, and Karow (2009) modelled the seismicity associated to fault reactivation during ice advance and retreat obtaining plausible earthquake scenarios of magnitude M w ≈8.…”

Section: Implications Of Hydrogeology For the Slope Stability On Himentioning

confidence: 99%

Fluid flow and pore pressure development throughout the evolution of a trough mouth fan, western Barents Sea

et al. 2019

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Using a combination of geophysical and geotechnical data from Storfjorden Trough Mouth Fan off southern Svalbard, we investigate the hydrogeology of the continental margin and how this is affected by Quaternary glacial advances and retreats over the continental shelf. The geotechnical results show that plumites, deposited during the deglaciation, have high porosities, permeabilities and compressibilities with respect to glacigenic debris flows and tills. These results together with margin stratigraphic models obtained from seismic reflection data were used as input for numerical finite element models to understand focusing of interstitial fluids on glaciated continental margins. The modelled evolution of the Storfjorden TMF shows that tills formed on the shelf following the onset of glacial sedimentation (ca. 1.5 Ma) acted as aquitards and therefore played a significant role in decreasing the vertical fluid flow towards the sea floor and diverting it towards the slope. The model shows that high overpressure ratios (up to λ ca. 0.6) developed below the shelf edge and on the middle slope. A more detailed model for the last 220 kyrs accounting for ice loading during glacial maxima shows that the formation of these aquitards on the shelf focused fluid flow towards the most permeable plumite sediments on the slope. The less permeable glacigenic debris flows that were deposited during glacial maxima on the slope hinder fluid evacuation from plumites allowing high overpressure ratios (up to λ ca. 0.7) to develop in the shallowest plumite layers. These high overpressures likely persist to the Present and are a critical precondition for submarine slope failure.

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Postglacial mass movements and depositional environments in a high-latitude fjord system – Hardangerfjorden, Western Norway

Cited by 35 publications

References 52 publications

Glacier outburst floods reconstructed from lake sediments and their implications for Holocene variations of the plateau glacier Folgefonna in western Norway

Glacier outburst floods reconstructed from lake sediments and their implications for Holocene variations of the plateau glacier Folgefonna in western Norway

Glacial sedimentation, fluxes and erosion rates associated with ice retreat in Petermann Fjord and Nares Strait, north-west Greenland

Fluid flow and pore pressure development throughout the evolution of a trough mouth fan, western Barents Sea

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